AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE PUEBLO CO 450 AM MST SAT DEC 29 2007 .SHORT TERM... (TODAY AND TONIGHT) ...NEW RECORD LOW TEMPERATURE AT ALAMOSA THIS MORNING(12/29)... ...POTENTIAL FOR STRONG/DAMAGE WINDS EAST PIKES PEAK/RAMPART RANGE LATE TONIGHT... CURRENTLY...LOW TEMPERATURE FOR ALAMOSA...SO FAR...HAS BEEN -29F AND THAT IS A NEW RECORD FOR 12/29. THE OLD RECORD WAS -28F/1966. THERE IS STILL PLENTY OF CHANCES FOR THE ALAMOSA TEMPERATURE TO DROP FURTHER EARLY THIS MORNING. MEANWHILE...THE OTHER LOW LYING AREAS(E.G. VALLEYS) WERE AROUND...OR JUST BELOW...0F. WESTERLY CHINOOK FLOW IS ALREADY SHOWING ITSELF WITH TEMPERATURES STEADY OR SLOWLY WARMING DURING THE NIGHT JUST WEST OF I-25 FROM 6K-9K FT. TEMPERATURES HAVE WARMED INTO THE TEENS AND 20S WITH COLORADO SPRINGS...PUEBLO WEST...AND CANON CITY WARMING INTO THE 20S...WHILE LOWER ARKANSAS TEMPERATURE READINGS (KPUB...KLHX...KLAA) ARE STILL IN THE SINGLE DIGITS. WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES REVEALED WEST- NORTHWEST FLOW ACROSS A LARGE PORTION OF THE WESTERN US. NEXT SIGNIFICANT UPPER LEVEL JET WAS ABOUT TO MOVE INTO THE GREAT BASIN. TODAY...WESTERLY CHINOOK FLOW WILL CONTINUE ACROSS THE CENTRAL ROCKIES. A LITTLE MORE MIXING AND SUNSHINE SHOULD ALLOW FOR SLIGHTLY WARMER TEMPERATURES...EXCEPT IN THE SAN LUIS VALLEY CENTER FLOOR WHERE THE TRAPPED COLD AIR/STRONG INVERSION/LOW SUN ANGLE SHOULD MAINTAIN SLOWLY RISING TEMPERATURES AND MAYBE GETTING INTO THE TEENS FOR ALAMOSA. WENT BELOW MOS GUIDANCE...ESPECIALLY MET MOS...FOR ALS TODAY. THERE MAY BE ENOUGH MOISTURE AND OROGRAPHIC WIND COMPONENT TO GENERATE SOME SNOWFALL ACROSS THE SOUTHWEST/CENTRAL MOUNTAINS AROUND THE CONTINENTAL DIVIDE LATE THIS AFTERNOON. TONIGHT...INTERESTING SCENARIO POSSIBLY DEVELOPING ACROSS PORTIONS OF SOUTHERN CO. MIDDLE TO UPPER LEVEL FLOW BECOMES MORE NORTHWESTERLY AS THE 100-120KT UPPER LEVEL JET STREAK MOVES OVER CO...EXCEPT WESTERLY FLOW AROUND MOUNTAIN TOP. MOUNTAIN TOP STABLE LAYER DOES DEVELOP FOR PIKES PEAK/RAMPART RANGE AND MAYBE THE WET/SANGRE DE CRISTO MOUNTAINS AFTER 05Z/30. 12KM NAM DOES HAVE SOME REVERSE SHEAR ALONG THE EAST SLOPES OF PIKES PEAK AND THE RAMPART RANGE...BUT THERE DOES NOT APPEAR TO BE MUCH OF A PRESSURE JUMP IN THE 12KM NAM DATA. TOUGH CALL. ALSO...THE VERTICAL SHEAR TRANSITIONS FROM REVERSE TO STRONG FORWARD SHEAR TOWARDS SUN MORNING. COULD SEE SOME WIND GUSTS OF 70-80 MPH ALONG THE EASTERN SLOPES OF PIKES PEAK AND 55-65 MPH ALONG THE EASTERN SLOPES OF RAMPART RANGE AFTER 05Z/30 AND ESPECIALLY JUST BEFORE SUNRISE SUN. ACROSS EL PASO COUNTY...IT WOULD MAINLY BE ALONG AND WEST OF I-25...WHERE EAST OF I-25 THE WIND WOULD BE RELATIVELY LIGHT. GIVEN THE POTENTIAL...WILL START A HIGH WIND WATCH(HW.A) FOR TELLER AND EL PASO COUNTIES LATER TONIGHT AND IT WILL CONTINUE INTO THE LONG TERM FORECAST. HIGH CHANCE/LIKELY/ CATEGORICAL POPS WILL BE FOUND ACROSS THE SOUTHWEST/CENTRAL MOUNTAINS ALONG THE CONTINENTAL DIVIDE. FOR AN 18 HOUR PERIOD...THERE COULD BE SNOW ACCUMULATIONS OF 1-6 INCHES FOR MAINLY THE HIGHER TERRAIN ABOVE 9K FT MSL. ALSO...BLOWING SNOW COULD BE A PROBLEM FOR THOSE AREAS... ESPECIALLY HIGH MOUNTAIN PASSES. WILL HOLD OFF ISSUING ANY SNOW/BLOWING SNOW ADVISORIES FOR THOSE AREAS AND HIT IT IN THE DIGITAL FORECAST DATABASE. THE OTHER CRITICAL WEATHER AREA WOULD BE EXTREMELY COLD TEMPERATURES IN THE SAN LUIS VALLEY CENTER FLOOR AROUND ALAMOSA. WILL GO A FEW CATEGORIES BELOW MOS GUIDANCE. THERE COULD...ALSO...BE DRASTIC TEMPERATURE CHANGES ALONG AND WEST OF I-25 CORRIDOR GIVEN THE WINDY AND NON-WINDY AREAS. METZE .LONG TERM... (SUNDAY THROUGH FRIDAY) MAIN CHALLENGE FOR SUNDAY WILL BE POTENTIAL FOR DAMAGING WINDS ACROSS THE MOUNTAINS AND ADJACENT EASTERN SLOPES...AND SNOW AMOUNTS FOR THE CENTRAL MOUNTAINS SUNDAY AFTERNOON AND NIGHT. JET STREAM SAGS SOUTHWARD OVER THE AREA ON SUNDAY AS NEXT SHORTWAVE BEGINS TO CARVE OUT THE TROF ACROSS THE NORTHERN US ROCKIES. INITIALLY CROSS-SECTIONS AND MODEL SOUNDINGS SHOW A POSSIBLE MOUNTAIN WAVE SET UP...WITH MTN TOP STABLE LAYER WITH MTN TOP WINDS OF 50-55 KTS...AND SOME REVERSE SHEAR ALOFT. MTN TOP STABLE LAYER IS NOT ALL THAT STRONG...WHICH LEADS TO SOME UNCERTAINTY AS TO HOW MUCH WIND WILL GET DEFLECTED DOWNWARD...BUT PER COORDINATION WITH BOU WILL ISSUE A HIGH WIND WATCH. INITIALLY NORTHWEST COMPONENT WILL FAVOR THE RAMPART RANGE AREA...AND PORTIONS OF WESTERN EL PASO COUNTY. AS UPPER JET MOVES IN ALOFT DURING THE AFTERNOON...INCREASING FORWARD SHEAR SHOULD DIMINISH HIGH WIND POTENTIAL. HOWEVER...BY THEN WINDS AT ALL MTN TOP LEVELS WILL BE NEARING SUSTAINED HIGH WIND CRITERIA OF 50 MPH. IN FACT BY AFTERNOON MTN TOP WINDS IN THE NAM12 INCREASE TO 60-70 KTS SO MTN TOP WINDS WILL BE VERY WINDY TO SAY THE LEAST. THUS...WILL INCLUDE THE HIGHER PEAKS OF THE SANGRES AND WET MOUNTAINS IN THE HIGH WIND WATCH AS WELL. WITH THE MAIN ENERGY STILL TO OUR WEST...LEE TROF STAYS PINNED UP ALONG THE EASTERN SLOPES OF THE SE MTS...SO STRONG GUSTY WINDS WILL MAINLY STAY CONFINED TO AREAS ALONG/WEST OF INTERSTATE 25. ANYWHERE WHERE THE WINDS PICK UP OVER OLD SNOW COVER...BLOWING SNOW COULD BE AN ISSUE...ESPECIALLY OVER THE MOUNTAIN PASSES...AND ALONG I-25 OVER MONUMENT HILL. LIGHT SNOW IS EXPECTED TO CONTINUE ON SUNDAY...THEN RAMP UP SUNDAY AFTERNOON AND NIGHT AS THE NEXT SHORTWAVE TROF/UPPER JET MOVES ACROSS THE STATE. CENTRAL MOUNTAINS MAY PICK UP ANOTHER 2-6 INCHES OF SNOWFALL FROM SUN AFTERNOON THROUGH SUNDAY NIGHT. THE HIGHER ELEVATIONS OF THE SAWATCH AND MOSQUITO RANGES MAY ALSO SEE WINDS NEARING HIGH WIND CRITERIA WITH SUSTAINED VALUES NEARING 50 MPH. HAVE DECIDED NOT TO INCLUDE THEM IN THE HIGH WIND WATCH...AS THIS COULD BE ADDRESSED IN A SNOW AND BLOWING SNOW ADVISORY. LATER SHIFTS WILL MONITOR THIS POTENTIAL. AS TROF MOVES ACROSS SUNDAY NIGHT...VERY COLD AIR WILL SPILL SOUTHEASTWARD BEHIND THE COLD FRONT. COULD SEE SOME JET INDUCED SNOW BANDS ACROSS THE EASTERN MOUNTAINS AND SOUTHEAST PLAINS SUNDAY NIGHT. GFS IS STILL DEPICTING THIS SCENARIO...WHILE NAM12 SUGGESTS IT WILL BE TOO DRY. SINCE NAM SEEMS TO HAVE A RATHER DRY BIAS LATELY...WILL GO CLOSER TO THE GFS SOLUTION AND KEEP SOME LOW GRADE POPS ACROSS ALL OF THE SOUTHEAST. MONDAY WILL BE COLD THOUGH SOME GUSTY WINDS MAY HELP TEMPS RISE TO NEAR 30 ACROSS PORTIONS OF THE SE PLAINS. MTS WILL SEE TEMPS TOP OUT ONLY IN THE SINGLE DIGITS AND TEENS. UPPER RIDGE BUILDS IN THROUGH THE MID WEEK BRINGING A RETURN OF DRIER AND WARMER WEATHER. -KT && .AVIATION... PER SHORT TERM DISCUSSION....VFR CONDITIONS WILL CONTINUE FOR COS...PUB...AND ALS TERMINAL FORECAST AREAS. THERE IS THE POTENTIAL FOR LOW LEVEL WIND SHEAR AT THE COS TERMINAL FORECAST AREA AFTER 09Z/30... SURFACE........02007KT 500 FOOT.......29030KT 1000 FOOT......29035KT 1500 FOOT......29045KT 2000 FOOT......30055KT METZE && .PUB WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON FOR COZ073-075-080>082-084-085. && $$ 17/31 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 417 AM MST SAT DEC 29 2007 .SHORT TERM... ...NEW RECORD LOW TEMPERATURE AT ALAMOSA THIS MORNING(12/29)... ...POTENTIAL FOR STRONG/DAMAGE WINDS EAST PIKES PEAK/RAMPART RANGE LATE TONIGHT... CURRENTLY...LOW TEMPERATURE FOR ALAMOSA...SO FAR...HAS BEEN -29F AND THAT IS A NEW RECORD FOR 12/29. THE OLD RECORD WAS -28F/1966. THERE IS STILL PLENTY OF CHANCES FOR THE ALAMOSA TEMPERATURE TO DROP FURTHER EARLY THIS MORNING. MEANWHILE...THE OTHER LOW LYING AREAS(E.G. VALLEYS) WERE AROUND...OR JUST BELOW...0F. WESTERLY CHINOOK FLOW IS ALREADY SHOWING ITSELF WITH TEMPERATURES STEADY OR SLOWLY WARMING DURING THE NIGHT JUST WEST OF I-25 FROM 6K-9K FT. TEMPERATURES HAVE WARMED INTO THE TEENS AND 20S WITH COLORADO SPRINGS...PUEBLO WEST...AND CANON CITY WARMING INTO THE 20S...WHILE LOWER ARKANSAS TEMPERATURE READINGS (KPUB...KLHX...KLAA) ARE STILL IN THE SINGLE DIGITS. WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES REVEALED WEST- NORTHWEST FLOW ACROSS A LARGE PORTION OF THE WESTERN US. NEXT SIGNIFICANT UPPER LEVEL JET WAS ABOUT TO MOVE INTO THE GREAT BASIN. TODAY...WESTERLY CHINOOK FLOW WILL CONTINUE ACROSS THE CENTRAL ROCKIES. A LITTLE MORE MIXING AND SUNSHINE SHOULD ALLOW FOR SLIGHTLY WARMER TEMPERATURES...EXCEPT IN THE SAN LUIS VALLEY CENTER FLOOR WHERE THE TRAPPED COLD AIR/STRONG INVERSION/LOW SUN ANGLE SHOULD MAINTAIN SLOWLY RISING TEMPERATURES AND MAYBE GETTING INTO THE TEENS FOR ALAMOSA. WENT BELOW MOS GUIDANCE...ESPECIALLY MET MOS...FOR ALS TODAY. THERE MAY BE ENOUGH MOISTURE AND OROGRAPHIC WIND COMPONENT TO GENERATE SOME SNOWFALL ACROSS THE SOUTHWEST/CENTRAL MOUNTAINS AROUND THE CONTINENTAL DIVIDE LATE THIS AFTERNOON. TONIGHT...INTERESTING SCENARIO POSSIBLY DEVELOPING ACROSS PORTIONS OF SOUTHERN CO. MIDDLE TO UPPER LEVEL FLOW BECOMES MORE NORTHWESTERLY AS THE 100-120KT UPPER LEVEL JET STREAK MOVES OVER CO...EXCEPT WESTERLY FLOW AROUND MOUNTAIN TOP. MOUNTAIN TOP STABLE LAYER DOES DEVELOP FOR PIKES PEAK/RAMPART RANGE AND MAYBE THE WET/SANGRE DE CRISTO MOUNTAINS AFTER 05Z/30. 12KM NAM DOES HAVE SOME REVERSE SHEAR ALONG THE EAST SLOPES OF PIKES PEAK AND THE RAMPART RANGE...BUT THERE DOES NOT APPEAR TO BE MUCH OF A PRESSURE JUMP IN THE 12KM NAM DATA. TOUGH CALL. ALSO...THE VERTICAL SHEAR TRANSITIONS FROM REVERSE TO STRONG FORWARD SHEAR TOWARDS SUN MORNING. COULD SEE SOME WIND GUSTS OF 70-80 MPH ALONG THE EASTERN SLOPES OF PIKES PEAK AND 55-65 MPH ALONG THE EASTERN SLOPES OF RAMPART RANGE AFTER 05Z/30 AND ESPECIALLY JUST BEFORE SUNRISE SUN. ACROSS EL PASO COUNTY...IT WOULD MAINLY BE ALONG AND WEST OF I-25...WHERE EAST OF I-25 THE WIND WOULD BE RELATIVELY LIGHT. GIVEN THE POTENTIAL...WILL START A HIGH WIND WATCH(HW.A) FOR TELLER AND EL PASO COUNTIES LATER TONIGHT AND IT WILL CONTINUE INTO THE LONG TERM FORECAST. HIGH CHANCE/LIKELY/ CATEGORICAL POPS WILL BE FOUND ACROSS THE SOUTHWEST/CENTRAL MOUNTAINS ALONG THE CONTINENTAL DIVIDE. FOR AN 18 HOUR PERIOD...THERE COULD BE SNOW ACCUMULATIONS OF 1-6 INCHES FOR MAINLY THE HIGHER TERRAIN ABOVE 9K FT MSL. ALSO...BLOWING SNOW COULD BE A PROBLEM FOR THOSE AREAS... ESPECIALLY HIGH MOUNTAIN PASSES. WILL HOLD OFF ISSUING ANY SNOW/BLOWING SNOW ADVISORIES FOR THOSE AREAS AND HIT IT IN THE DIGITAL FORECAST DATABASE. THE OTHER CRITICAL WEATHER AREA WOULD BE EXTREMELY COLD TEMPERATURES IN THE SAN LUIS VALLEY CENTER FLOOR AROUND ALAMOSA. WILL GO A FEW CATEGORIES BELOW MOS GUIDANCE. THERE COULD...ALSO...BE DRASTIC TEMPERATURE CHANGES ALONG AND WEST OF I-25 CORRIDOR GIVEN THE WINDY AND NON-WINDY AREAS. METZE .LONG TERM... (SUNDAY THROUGH FRIDAY) MAIN CHALLENGE FOR SUNDAY WILL BE POTENTIAL FOR DAMAGING WINDS ACROSS THE MOUNTAINS AND ADJACENT EASTERN SLOPES...AND SNOW AMOUNTS FOR THE CENTRAL MOUNTAINS SUNDAY AFTERNOON AND NIGHT. JET STREAM SAGS SOUTHWARD OVER THE AREA ON SUNDAY AS NEXT SHORTWAVE BEGINS TO CARVE OUT THE TROF ACROSS THE NORTHERN US ROCKIES. INITIALLY CROSS-SECTIONS AND MODEL SOUNDINGS SHOW A POSSIBLE MOUNTAIN WAVE SET UP...WITH MTN TOP STABLE LAYER WITH MTN TOP WINDS OF 50-55 KTS...AND SOME REVERSE SHEAR ALOFT. MTN TOP STABLE LAYER IS NOT ALL THAT STRONG...WHICH LEADS TO SOME UNCERTAINTY AS TO HOW MUCH WIND WILL GET DEFLECTED DOWNWARD...BUT PER COORDINATION WITH BOU WILL ISSUE A HIGH WIND WATCH. INITIALLY NORTHWEST COMPONENT WILL FAVOR THE RAMPART RANGE AREA...AND PORTIONS OF WESTERN EL PASO COUNTY. AS UPPER JET MOVES IN ALOFT DURING THE AFTERNOON...INCREASING FORWARD SHEAR SHOULD DIMINISH HIGH WIND POTENTIAL. HOWEVER...BY THEN WINDS AT ALL MTN TOP LEVELS WILL BE NEARING SUSTAINED HIGH WIND CRITERIA OF 50 MPH. IN FACT BY AFTERNOON MTN TOP WINDS IN THE NAM12 INCREASE TO 60-70 KTS SO MTN TOP WINDS WILL BE VERY WINDY TO SAY THE LEAST. THUS...WILL INCLUDE THE HIGHER PEAKS OF THE SANGRES AND WET MOUNTAINS IN THE HIGH WIND WATCH AS WELL. WITH THE MAIN ENERGY STILL TO OUR WEST...LEE TROF STAYS PINNED UP ALONG THE EASTERN SLOPES OF THE SE MTS...SO STRONG GUSTY WINDS WILL MAINLY STAY CONFINED TO AREAS ALONG/WEST OF INTERSTATE 25. ANYWHERE WHERE THE WINDS PICK UP OVER OLD SNOW COVER...BLOWING SNOW COULD BE AN ISSUE...ESPECIALLY OVER THE MOUNTAIN PASSES...AND ALONG I-25 OVER MONUMENT HILL. LIGHT SNOW IS EXPECTED TO CONTINUE ON SUNDAY...THEN RAMP UP SUNDAY AFTERNOON AND NIGHT AS THE NEXT SHORTWAVE TROF/UPPER JET MOVES ACROSS THE STATE. CENTRAL MOUNTAINS MAY PICK UP ANOTHER 2-6 INCHES OF SNOWFALL FROM SUN AFTERNOON THROUGH SUNDAY NIGHT. THE HIGHER ELEVATIONS OF THE SAWATCH AND MOSQUITO RANGES MAY ALSO SEE WINDS NEARING HIGH WIND CRITERIA WITH SUSTAINED VALUES NEARING 50 MPH. HAVE DECIDED NOT TO INCLUDE THEM IN THE HIGH WIND WATCH...AS THIS COULD BE ADDRESSED IN A SNOW AND BLOWING SNOW ADVISORY. LATER SHIFTS WILL MONITOR THIS POTENTIAL. AS TROF MOVES ACROSS SUNDAY NIGHT...VERY COLD AIR WILL SPILL SOUTHEASTWARD BEHIND THE COLD FRONT. COULD SEE SOME JET INDUCED SNOW BANDS ACROSS THE EASTERN MOUNTAINS AND SOUTHEAST PLAINS SUNDAY NIGHT. GFS IS STILL DEPICTING THIS SCENARIO...WHILE NAM12 SUGGESTS IT WILL BE TOO DRY. SINCE NAM SEEMS TO HAVE A RATHER DRY BIAS LATELY...WILL GO CLOSER TO THE GFS SOLUTION AND KEEP SOME LOW GRADE POPS ACROSS ALL OF THE SOUTHEAST. MONDAY WILL BE COLD THOUGH SOME GUSTY WINDS MAY HELP TEMPS RISE TO NEAR 30 ACROSS PORTIONS OF THE SE PLAINS. MTS WILL SEE TEMPS TOP OUT ONLY IN THE SINGLE DIGITS AND TEENS. UPPER RIDGE BUILDS IN THROUGH THE MID WEEK BRINGING A RETURN OF DRIER AND WARMER WEATHER. -KT && .AVIATION... PER SHORT TERM DISCUSSION....VFR CONDITIONS WILL CONTINUE FOR COS...PUB...AND ALS TERMINAL FORECAST AREAS. THERE IS THE POTENTIAL FOR LOW LEVEL WIND SHEAR AT THE COS TERMINAL FORECAST AREA AFTER 09Z/30... SURFACE........02007KT 500 FOOT.......29030KT 1000 FOOT......29035KT 1500 FOOT......29045KT 2000 FOOT......30055KT METZE && .PUB WATCHES/WARNINGS/ADVISORIES... HIGH WIND WATCH FROM THIS EVENING THROUGH SUNDAY AFTERNOON FOR COZ073-075-080>082-084-085. && $$ 17/31 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 1108 PM EST SUN DEC 30 2007 .SYNOPSIS... LOW PRESSURE ALONG THE VIRGINIA COAST WILL PASS SOUTHEAST OF LONG ISLAND OVERNIGHT...BEFORE DEPARTING BY EARLY MONDAY AFTERNOON. WEAK HIGH PRESSURE THEN QUICKLY PASSES TO THE SOUTH OF THE AREA. A POTENT ALBERTA CLIPPER SYSTEM WILL MOVE ACROSS THE REGION ON TUESDAY...USHERING BITTERLY COLD AIR BEHIND IT AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION. DRY WEATHER IS THEN EXPECTED INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... DRY SLOT HAD WORKED ITS WAY INTO THE AREA...WITH EARLIER SNOW/SLEET WELL NORTH/WEST OF NYC CHANGING TO FREEZING DRIZZLE AS WE LOSE MID LEVEL MOISTURE AND AS TEMPS ALOFT WARM ABOVE FREEZING. SURFACE TEMPERATURES FARTHER SOUTH/EAST HAVE REMAINED ABOVE FREEZING...WITH PRECIPITATION PRIMARILY RAIN. LIGHT NORTHERLY FLOW OVER SOUTHERN CT SHOULD ALLOW TEMPS TO DROP TO AT OR JUST BELOW FREEZING OVER MOST INTERIOR SECTIONS AS WELL...WITH PRECIP CHANGING OVER TO LIGHT FREEZING DRIZZLE/SLEET THERE AS WELL. BAND OF HEAVIER PRECIP ORGANIZING OVER EASTERN PA MAY YET PIVOT EASTWARD INTO THE AREA...IN TANDEM WITH COLDER AIR MOVING BACK INTO THE AREA ON THE BACK SIDE OF LOW PRESSURE MOVING FROM THE VA COAST TO SE OF MONTAUK OVERNIGHT...WITH A CHANGE BACK TO MOSTLY SNOW IN ORANGE/PUTNAM/W PASSAIC COUNTIES AFTER MIDNIGHT...AND SNOW/SLEET ELSEWHERE LATE. HAVE KEPT WINTER WX ADVISORY UP WHERE IT WAS ALREADY POSTED...BUT HAVE CUT ACCUMULATIONS TO 2-4 INCHES FOR ORANGE/PUTNAM/W PASSAIC AND 1-3 ELSEWHERE...WITH ADDED MENTION OF SOME ICING. AS THE LOW PASSES SE OF LONG ISLAND LATE TONIGHT...NORTHWEST WINDS WILL PICK UP ACROSS THE AREA. ENOUGH COLD AIR WILL FILTER DOWN INTO THE AREA TO TURN PRECIP OVER TO SNOW/SLEET IN THE COUNTIES JUST SOUTH OF THE ADVISORY AREA INCLUDING PORTIONS OF NYC...AND A COATING TO AN INCH OF SNOW MAY STILL BE POSSIBLE. HAVE GONE WITH SLIGHTLY WARMER MINS IN MOST PLACES PER OBS AND BLEND OF NAM 2M/MAV TEMPS UNDER CUT A COUPLE OF DEGREES...WITH MID 30S ACROSS LONG ISLAND AND LOWER 30S ELSEWHERE. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... PRECIP WILL WIND DOWN AS A PERIOD OF SNOW BEFORE TAPERING OFF WITH MINOR ADDITIONAL ACCUMULATIONS. SKIES CLEAR OUT DURING THE AFTERNOON AS HIGH PRES MOVES INTO THE MID-ATLANTIC BY MIDDAY...THEN OFFSHORE MON NIGHT. A CLIPPER SYSTEM WILL MOVE ACROSS THE REGION ON TUE... MOVING OFFSHORE BY TUE NIGHT. WILL CONTINUE TO CARRY LIKELY POPS...AS THERE WEREN/T ANY MAJOR CHANGES THAT WERE NEEDED TO BE MADE TO THE PREVIOUS FCST. MODELS SEEM TO HAVE A GOOD HANDLE ON THIS UPCOMING SYSTEM. TEMPS WILL BE COLD ENOUGH TO SUPPORT SNOW THE THE NORTH...AND WARM ENOUGH FOR RAIN TO THE SOUTH. PRECIP WILL TAPER OFF AS ALL SNOW TUE NIGHT. WINTER WEATHER ADVISORIES MAY HAVE TO BE POSTED FOR ORANGE/PUTNAM/NORTHERN FAIRFIELD COUNTIES FOR TUE...AS OVER 3" SNOW COULD ACCUMULATE...BUT WILL WAIT FOR FCST TO BE REFINED. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS THE STORM HEADS OUT FARTHER INTO THE CANADIAN MARITIMES ON WED...THE TRAILING H5 TROUGH AXIS PASSES EAST. H8 FLOW IS WEAKLY CYCLONIC...SO MOST OF THE AREA SHOULD REMAIN DRY BUT WITH ABUNDANT INSTABILITY STRATOCU. EASTERN SECTIONS COULD SEE SOME SNOW SHOWERS AS DEEPER MOISTURE WRAPS AROUND THE BACK SIDE OF THE DEPARTING LOW. TEMPERATURES WILL BE ON THE COLD SIDE...DROPPING TO AROUND -12C TO -14C AT 925 MB IN THE AFTERNOON. IT MIGHT BE A DAY WHERE HIGHS OCCUR IN THE MORNING...PROBABLY REACHING ONLY 25-30. GUSTY NORTHWEST WINDS WILL MAKE IT FEEL EVEN COLDER...WITH WIND CHILLS DROPPING TO AROUND ZERO LATE WED NIGHT IN NYC....AND -5 TO -10 IN SOME INLAND SPOTS. RIDGING AT THE SURFACE AND ALOFT BEGINS TO BUILD IN ON THU. IT WILL BE MOSTLY SUNNY...BUT STILL COLDER THAN NORMAL. LOW LEVEL THICKNESSES SUPPORT EVEN COLDER HIGH TEMPS THAN THOSE OF WED... REMAINING IN THE 20S THROUGHOUT. THE CENTER OF THE HIGH WILL MOVE OFF THE MID ATLANTIC COAST ON FRI...WITH A DEVELOPING RETURN FLOW. MODERATION WILL BE SLOWER THAN MOS SUGGESTS ON FRI...WITH HIGHS IN THE 30S THROUGHOUT...BUT SHOULD KICK IN FOR SAT/SUN WITH HIGHS IN THE 40S...PERHAPS NEARING 50 IN NYC METRO ON SUN. A WARM FRONT PASSING TO THE NORTH/WEST COULD BRING THICKENING HIGH/MID LEVEL CLOUDS SAT NIGHT AND SUN...BUT LOW LEVELS WILL REMAIN QUITE DRY...SO NO PRECIP EXPECTED. NEXT CHANCE OF PRECIP APPEARS TO BE LATE SUN NIGHT WITH THE APPROACH OF A COLD FRONT. TEMPS SHOULD RUN AT LEAST SEVERAL DEGREES WARMER THAN MOS WITH SOUTHERLY FLOW AND CLOUD COVER...MAKING FOR AN ALL RAIN EVENT SUN NIGHT. && .AVIATION /04Z MONDAY THROUGH FRIDAY/... CONDITIONS SHOULD DROP TO MVFR BY 01Z OR 02Z ACROSS WESTERN TERMINALS...02Z TO 03Z AT KISP...KBDR AND KGON. IFR/LIFR TO FOLLOW BETWEEN 03Z AND 06Z. LATEST ACARS SOUNDINGS ACROSS NYC INDICATE THAT THE GFS IS VERIFYING BETTER THAN THE NAM. THE WARM NOSE IN THE NAM IS ABOUT 2 DEGREES TOO HIGH AT 800 MB. THE RUC IS VERIFIES EVEN BETTER...BUT THIS IS TO BE EXPECTED SINCE IT USES ACARS SOUNDINGS IN IT. -SN IS EXPECTED TO BE THE DOMINANT P-TYPE AT KSWF BUT MAY BRIEFLY MIX WITH -IP AT TIMES THROUGH 09Z. LOOKING UPSTREAM...KMPO (AND KDXR) HAVE CHANGED TO FZRA OVER THE LAST HOUR. THIS IS BOTHERSOME AND INDICATES THAT WARMER AIR IS MOVING IN ALOFT. RUC INDICATES ABOUT A 3 HOUR PERIOD OF A WARM NOSE AT KSWF BETWEEN 04Z AND 07Z WHICH IS WHEN THERE COULD BE SOME IP MIXING IN...BUT IF THE WARM LAYER IS LARGER THAN THE PROFILE INDICATES WE COULD BE LOOKING AT PRECIP CHANGING TO FZRA. NOT CONFIDENT ENOUGH THAT THIS WILL OCCUR...SO HAVE NOT INCLUDED IN THE TAF. KJFK...KLGA...KEWR...KTEB AND KISP SHOULD ALL REMAIN RAIN FOR THE MAJORITY OF THE EVENT...BUT COULD CHANGE OVER TO -SN AT THE END (BETWEEN 09Z AND 12Z). SO ACCORDING TO THE RUC...THE REMAINING TERMINALS (KBDR...KGON AND KHPN)...WHICH WERE THE TOUGH ONES SINCE THEY REMAIN THE CLOSEST TO THE RAIN/SNOW LINE...ALL REMAIN -RA FOR MAJORITY OF THE EVENT AS WELL POSSIBLY CHANGING TO -SN AT THE END TOO. E/NE WINDS WILL GRADUALLY BACK TO THE N THEN NW AS THE COASTAL LOW PASSES TO THE SOUTH AND EAST LATE TONIGHT/EARLY MON MORNING. PRECIP SHOULD TAPER OFF FROM SW TO NE BETWEEN 12Z AND 15Z AND IT MAY NEED TO BE EXTENDED AN HOUR OR TWO LONGER THAN WHAT IS IN THE 00Z TAFS...BUT WILL WATCH RADAR AND ADJUST ACCORDINGLY. VFR CONDITIONS RETURN TO ALL TERMINALS BETWEEN 14Z AND 16Z WITH ONLY GUSTY NW WINDS TO CONTEND WITH. SUSTAINED WINDS SHOULD RANGE BETWEEN 12 AND 17KT WITH GUSTS BETWEEN 25 AND 30 KT. OUTLOOK FOR 00Z TUESDAY THROUGH THURSDAY...VFR REMAINS THROUGH MONDAY NIGHT. SUB-VFR CONDITIONS ARE AGAIN LIKELY TUESDAY AND TUESDAY EVENING AS AN ALBERTA CLIPPER LOW AND COLD FRONT PASS ACROSS THE AREA. RAIN NEAR THE COAST...RAIN/SNOW INTERIOR. THIS WILL BE FOLLOWED BY GUSTY W-NW FLOW LATER TUE NIGHT THROUGH THU AS THE OFFSHORE LOW INTENSIFIES AND DRAWS DOWN ARCTIC AIR. LIGHT SNOW SHOWERS OR FLURRIES WILL BE POSSIBLE ON WEDNESDAY...OTHERWISE DRY. && .MARINE... TODAY THROUGH TUESDAY NIGHT... SCA DELAYED FOR THE SOUND/HARBOR/BAYS UNTIL WINDS PICK UP ON THE BACK SIDE OF THE DEPARTING COASTAL LOW. OTHERWISE...SCA UP FOR THE OCEAN AS WIND GUSTS WILL BE OVER 25 KT...WITH SEAS 4-6 FT. AFTER THE LOW DEPARTS ON MON...WEAK HIGH PRES WILL BUILD TO THE SOUTH. WITH A SHOT OF CAA...AND A TIGHT PRESSURE GRADIENT ON THE WATERS...THERE COULD BE OCNL GALE FORCE GUSTS DURING MON AFTERNOON. WILL CARRY STRONG SCA FOR NOW...AND LET MID SHIFT DECIDE IF GALES WILL BE MORE PREVALENT. FLAGS COME DOWN FROM WEST TO EAST MON EVENING...ENDING ON ALL WATERS BY MIDNIGHT. TRANQUIL CONDITIONS THEN EXPECTED THROUGH MIDDAY TUE. ANOTHER SYSTEM WILL BRING AT LEAST SCA CONDITIONS WITH GALES POSSIBLE ONCE AGAIN. DUE TO STRONGER CAA AND A STRONGER GRADIENT...THINK THERE WILL BE A BETTER CHANCE FOR GALES LATE TUE. WEDNESDAY THROUGH FRIDAY NIGHT... A STRONG PRESSURE GRADIENT AND LOW LEVEL CAA/INSTABILITY WILL COMBINE TO PRODUCE NW GALES ON THE OCEAN WED THROUGH THU MORNING... AND SCA CONDITIONS ELSEWHERE. SCA CONDITIONS ON THE OCEAN SHOULD COME TO AN END LATE THU NIGHT AS HIGH PRESSURE BUILDS OVER THE WATERS...BUT COULD RETURN TO THE EASTERN OCEAN WATERS FRI NIGHT VIA A STRENGTHENING WSW FLOW AS THE CORE OF THE HIGH PASSES OFF THE MID ATLANTIC COAST. && .HYDROLOGY... COASTAL LOW IS EXPECTED TO PRODUCE 1/2 TO 2/3 INCH QPF THROUGH MON MORNING. ANOTHER SYSTEM ON TUE COULD PRODUCE UP TO 1/2 INCH QPF. && .EQUIPMENT... KOKX WSR-88D IS FULLY OPERATIONAL...THOUGH A SOFTWARE/HARDWARE ISSUE WITH OUR AWIPS HAS CAUSED INTERRUPTIONS OF EXTERNAL DISSEMINATION. PLEASE CONTACT US IF YOU NOTICE THAT KOKX RADAR IS NOT AVAILABLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR CTZ005>008. NY...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR NYZ067>070. NJ...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR NJZ002. MARINE...SMALL CRAFT ADVISORY FROM 11 AM TO 6 PM EST MONDAY FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EST MONDAY NIGHT FOR ANZ350-353. SMALL CRAFT ADVISORY UNTIL 6 PM EST MONDAY FOR ANZ355. && $$ SYNOPSIS...BG/MPS NEAR TERM...BG SHORT TERM...MPS LONG TERM...BG AVIATION...AL MARINE...BG/MPS HYDROLOGY...BG/MPS ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 917 PM EST SUN DEC 30 2007 .SYNOPSIS... LOW PRESSURE NEAR THE DELMARVA REGION WILL MOVE NORTHEAST AND DEEPEN OVERNIGHT...PASSING SOUTH OF LONG ISLAND. THE LOW WILL CONTINUE TO HEAD NORTHEAST ALONG THE EASTERN NEW ENGLAND COAST MONDAY. SNOW WILL OVERSPREAD THE REGION OVERNIGHT AND TAPER OFF TO SNOW SHOWERS BY LATE MONDAY MORNING. ANOTHER LOW PRESSURE SYSTEM WILL IMPACT THE REGION TUESDAY AND TUESDAY NIGHT...BRINGING ANOTHER ROUND OF ACCUMULATING SNOWFALL. MUCH COLDER TEMPERATURES WILL FOLLOW IN THE WAKE OF THIS STORM FOR THE MIDDLE AND END OF THE WEEK. && .NEAR TERM /THROUGH MONDAY/... ONCE AGAIN WE ARE DEALING WITH A DOUBLE BARREL STORM SYSTEM BASED ON THE LATEST 13KM RUC AND MSAS ANALYSIS. THIS TIME THE COASTAL LOW REALLY IS THE PRIMARY STORM SYSTEM CURRENTLY FORMING NEAR THE DELMARVA REGION WITH A SECONDARY/INVERTED TROUGH OVER THE UPPER MID ATLANTIC REGION/PA. IT WILL BE A FAST MOVING SYSTEM BASED ON THE FAST SOUTHWESTERLY FLOW ALOFT...AND THE MAIN SFC WAVE NEVER CLOSES OFF BASED ON THE MODEL GUIDANCE. THE RADAR TRENDS FROM THE KENX RADAR AND NEIGHBORING SITES HAS BEEN FOR THE ATMOSPHERE TO SATURATE AND COOL. WE HAVE SEEN SUDDEN EVAPORATIVE COOLING/WET BULBING AT KPOU AROUND 00Z...AND WE EVEN HAVE HAD A FEW FLAKES HERE AT CESTM...AND AT THE AIRPORT BETWEEN 01Z-02Z. THE MAIN SYNOPTIC FORCING WITH THIS INITIAL BURST OF SNOW WILL BE WITH THE INVERTED TROUGH WITH ITS ASSOCIATED ISENTROPIC LIFT. AROUND 06Z...THE H850-700 FRONTOGENETICAL FORCING WITH THE COASTAL LOW SHOULD PRODUCE A DECENT MESOSCALE SNOWBAND OVER THE CAPITAL REGION...THE BERKSHIRES...SRN VT...AND THE CATSKILLS. SNOW RATES MAY EXCEED AN INCH AN HOUR FOR A 3-HOUR STRETCH. WE HAVE NOT CHANGED HEADLINES...BECAUSE THE MAX QPF FROM THE PLUMES...ENSEMBLES...GFS...AND NAM PER THE 18Z GUIDANCE IS STILL AROUND A HALF AN INCH. THIS EVENT WILL GO DOWN TO SNOW RATIOS. IF IT IS AROUND 10:1...THEN THE CURRENT HEADLINES LOOK FINE. WE ARE GOING TO STICK WITH THEM. HIGHER SNOW RATIOS WOULD MAKE IT DICEY FOR THE CAPITAL REGION...AND TACONICS. WE BELIEVE THE HIGHER ELEVATIONS WILL SATURATE THE QUICKEST HAVE THE BEST CHANCE OF GETTING 7 OR MORE INCHES IN 12 HOURS. SOME SLEET SHOULD STILL MIX IN OVER THE MID HUDSON VALLEY...SOUTHERN TACONICS...AND LITCHFIELD HILLS WITH THERMAL PROFILES INDICATING ABOVE FREEZING AIR MOVING IN THE 850-700 LAYER THERE. KPOU AT 02Z IS NOW REPORTING UNKNOWN PCPN...WHICH IS LIKELY SLEET. THEREFORE...KEEPING A WINTER WEATHER ADVISORY LOOKS GOOD. THE SNOW SHOULD END QUICKLY FROM SOUTH TO NORTH BETWEEN 12Z-16Z...WITH THE SNOW LINGERING WITH THE H850-700 DEFORMATION AXIS FROM ALY NORTH AND WEST TO THE CYCLONE. WE WILL RETOOLING POPS AND TEMPS IN THE GRIDS A BIT AND KEEP THE SNOWFALL ACCUMULATIONS INTACT WITH 5-10 INCHES OVER THE ERN CATSKILLS...BERKSHIRES...AND SRN VT. EXPECT 3-8 INCHES EVERYWHERE ELSE IN THE ALY FCST AREA. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...BRIEF BREAK IN BETWEEN EVENTS MONDAY EVENING AS WEAK RIDGE BUILDS IN. NEXT SYSTEM FOR TUESDAY AND TUESDAY NIGHT...OVERALL THE MODELS HAVE TRENDED SOUTHWARD WITH SURFACE LOW OVER THE PAST COUPLE OF DAYS. THERE HAS BEEN ONLY MINOR CHANGES BETWEEN THE 06Z AND 12Z RUNS OF THE GFS BUT THE NAM HAS TRENDED JUST A TAD FARTHER SOUTH. BASICALLY HAVE A LOW PASSING OVER NEW YORK STATE WITH COASTAL DEVELOPMENT BEING INITIATED TUESDAY AFTERNOON WITH THE COASTAL LOW NOT BECOMING THE DOMINATE LOW UNTIL WEDNESDAY OFF THE NEW ENGLAND COAST. THE NORTHERN AND SOUTHERN STREAM PHASES WITH THIS SYSTEM AND A DEEP TROUGH DIGS OVER THE EASTERN UNITED STATES. WILL LIKELY NEED HEADLINES FOR THIS STORM WITH MODERATE/HEAVY SNOW FOR THE WESTERN ADIRONDACKS...UPPER HUDSON VALLEY AND SOUTHERN VERMONT AND LIGHT/ MODERATE SNOW ACROSS THE REST OF THE FORECAST AREA. AT THIS TIME...WILL MENTION IN HAZARDOUS WEATHER OUTLOOK AND DEAL WITH TONIGHT`S STORM FIRST. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... RELATIVELY QUIET PERIOD WEATHER WISE IN TERMS OF ADDITIONAL LOW PRESSURE SYSTEMS MOVING THROUGH THE FORECAST AREA. INITIALLY...THE REGION WILL BE DOMINATED BY A COLD ARCTIC AIRMASS WEDNESDAY THROUGH FRIDAY MORNING. MAY EVEN NEED OUR FIRST WIND CHILL HEADLINES WEDNESDAY NIGHT AS A WIND OF AROUND 10 MPH REMAINS AND TEMPS DROP TO BETWEEN 10 BELOW ZERO AND 10 ABOVE. MAINLY DRY WEDNESDAY THROUGH FRIDAY MORNING AS THE HIGH BUILDS OVER THE REGION...BUT THERE WILL BE SOME LEFTOVER CYCLONIC FLOW/LAKE EFFECT SNOW SHOWERS ON WEDNESDAY. TEMPS THURSDAY NIGHT ALSO LIKELY TO GET INTO THE 10 BELOW TO 10 ABOVE RANGE...BUT LITTLE IF ANY WIND EXPECTED THEN. MAINLY DRY INTO THE EARLY PART OF NEXT WEEKEND WITH A CHANCE OF PCPN SATURDAY NIGHT INTO SUNDAY NIGHT PRIMARILY THE RESULT OF A WARM ADVECTION PATTERN AMD WEAK DISTURBANCES MOVING THROUGH. && .AVIATION /00Z MONDAY THROUGH THURSDAY/... LOW PRESSURE MOVING NORTHEAST FROM THE DELMARVA REGION AROUND 03Z WILL SPREAD A MODERATE TO HEAVY SNOWFALL ACROSS ERN NY OVERNIGHT. THE LOW WILL BE NEAR CAPE COD BY 12Z MON...BEFORE MOVING FURTHER NORTHEAST INTO THE CANADIAN MARITIMES BY 18Z MON. VFR CONDITIONS WILL RAPIDLY DETERIORATE TO MVFR/IFR CIGS AND VSBYS BTWN 01Z-05Z FROM KPOU NORTH TO KGFL. AFTER 05Z...EXPECT WIDESPREAD IFR/LIFR CIGS AND VSBYS IN MODERATE TO HEAVY SNOWFALL. BTWN 13Z-16Z...THE SNOW WILL TAPER FROM SOUTH TO NORTH WITH IFR/MVFR CIGS AND VSBYS. EXPECT FLIGHT CONDITIONS TO IMPROVE TO MVFR/VFR LEVELS FOR CIGS/VSBYS IN THE 16Z-20Z TIME FRAME. VFR CONDITIONS WILL RETURN AFTER 20Z MON. WINDS WILL BE LIGHT FROM THE N/NE AT 5 KTS OR LESS TIL ABOUT 12Z. THE WINDS WILL SHIFT THE W/NW AT 8-15 12Z-18Z. THE WINDS WILL BE BRISK AT KALB IN THE LATE AM INTO THE PM DUE TO CHANNELING DOWN THE MOHAWK RIVER VALLEY WITH SUSTAINED W/NW WINDS AROUND 15 KTS AND GUSTS TO 25 KTS. OUTLOOK... MON PM...BECOMING VFR. TUE...MVFR/IFR CIGS/VSBYS WITH SN. WED...VFR...WDLY SCT -SHSN. THU-FRI...VFR...NO SIG WX. && .HYDROLOGY... WE ARE NOT EXPECTING ANY HYDROLOGICAL ISSUES ON THE MAIN STEM RIVERS THROUGH THE NEXT SEVEN DAYS. MOST OF THE PCPN EXPECTED THROUGH NEXT SUNDAY WILL BE IN THE FORM OF SNOW OR SLEET. SNOW MELT WILL BE MINIMAL OR NON-EXISTENT MOST OF THIS PERIOD WITH AT OR BELOW FREEZING TEMPERATURES THROUGH FRIDAY...AND A SLOW WARMUP DURING NEXT WEEKEND. IN THE WAKE OF THE CLIPPER TYPE SYSTEM TUESDAY...THE MIDDLE OF THE WEEK LOOKS VERY COLD WHICH WILL START TO BUILD ICE AGAIN ON AREA RIVERS AND STREAMS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST MONDAY FOR CTZ001-013. NY...HEAVY SNOW WARNING FROM 7 PM THIS EVENING TO 10 AM EST MONDAY FOR NYZ047-051-058-063. WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST MONDAY FOR NYZ060-061-064>066. SNOW ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST MONDAY FOR NYZ032-033-038>043-048>050-052>054-059-082>084. MA...HEAVY SNOW WARNING FROM 7 PM THIS EVENING TO 10 AM EST MONDAY FOR MAZ001-025. VT...HEAVY SNOW WARNING FROM 7 PM THIS EVENING TO 10 AM EST MONDAY FOR VTZ013>015. && $$ SYNOPSIS...TAW/IAA NEAR TERM...TAW AVIATION...TAW ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 841 PM EST SUN DEC 30 2007 .SYNOPSIS... LOW PRESSURE WILL APPROACH FROM THE MID-ATLANTIC...PASSING SOUTH AND EAST OF LONG ISLAND DURING THE OVERNIGHT BEFORE DEPARTING BY EARLY MONDAY AFTERNOON. WEAK HIGH PRESSURE THEN QUICKLY PASSES TO THE SOUTH OF THE AREA. A CLIPPER SYSTEM WILL MOVE ACROSS THE REGION ON TUESDAY...USHERING BITTERLY COLD AIR BEHIND IT AS CANADIAN HIGH PRESSURE BUILDS INTO THE REGION. DRY WEATHER IS THEN EXPECTED INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... MODELS COMING INTO FAIR AGREEMENT REGARDING THE STORM SYSTEM CURRENTLY STRENGTHENING OVER THE SOUTHEAST. THE LOW WILL FIND ITSELF JUST OVER THE DELMARVA AREA BY 00Z...RAPIDLY DEEPENING FROM ABOUT 1010 MB TO 1003 MB AS IT MOVES NORTHEAST TO A POINT ABOUT 100 MILES SOUTH AND EAST OF KMTP TOWARDS DAYBREAK. MAIN ISSUE IS GOING TO BE PTYPE. BASED ON NAM AND GFS BUFKIT SOUNDINGS...LOOKS LIKE A FAIR AMOUNT OF WARM AIR WILL OVERSPREAD THE MIDDLE LAYERS OF THE ATMOSPHERE ACROSS THE REGION...MAINLY KEEPING PRECIP IN THE FORM OF RAIN FOR SOUTHERN LOCATIONS...MIXING WITH SLEET AFTER MIDNIGHT. FURTHER TO THE NORTH...PTYPE MAY START OUT AS A PERIOD OF RAIN BEFORE MIXING WITH AND CHANGING TO SNOW THIS EVENING. WILL ALSO SEE SLEET MIXING WITH THE SNOW DURING THE OVERNIGHT. THESE SIGNATURES WERE INDICATED ON BOTH NAM AND GFS BUFKIT SOUNDINGS. CHANGES WERE NOT NEEDED FOR THE WINTER WEATHER ADVISORY...AS 3-5" OF SNOW/SLEET WILL FALL ACROSS INTERIOR PORTIONS OF THE LOWER HUDSON VALLEY AND INTERIOR PORTIONS OF SOUTHERN CT. THERE MAY BE A THIN SWATH OF 1" TO MAYBE 2" ACROSS SOUTHERN PORTIONS OF THE LOWER HUDSON VALLEY AND INTO NORTHERN PORTIONS OF NORTHEAST NJ. NYC/LONG ISLAND AND IMMEDIATE COASTAL LOCALES ARE EXPECTED TO PICK UP LESS THAN AN INCH OF SLUSHY ACCUMULATION...AND MAINLY ON COLDER AND GRASSY SURFACES. WILL HAVE TO MONITOR NORTHERN AND WESTERN PORTIONS OF ORANGE COUNTY. QPF WAS A BIT HIGHER THAN PREVIOUSLY FCST. STILL THINK THERE WILL BE ENOUGH WARM AIR ALOFT TO CAP ACCUMULATIONS AT 5"...BUT NAM/GFS BUFKIT DATA DID INDICATE THAT UP TO 6" OF SNOW COULD ACCUMULATE. EVENING SHIFT WILL HAVE TO MONITOR TO DETERMINE IF A WARNING IS NEEDED IF MORE THAN 6" WOULD ACCUMULATE. IT/S CLOSE...BUT WILL HOLD AT A WINTER WEATHER ADVISORY WITH THIS PACKAGE. TOWARDS DAYBREAK...AS THE LOW MOVES TOWARDS THE GULF OF MAINE... NORTHWEST WINDS WILL PICK UP ACROSS THE AREA. ENOUGH COLD AIR WILL MIX DOWN TO THE AREA TO TURN PRECIP OVER TO SNOW BEFORE ENDING. WITH 1/2" TO 3/4" QPF EXPECTED...WILL HAVE TO ALSO MONITOR FOR ANY LOCALIZED URBAN FLOODING PROBLEMS WHERE PRECIP REMAINS MAINLY RAIN THROUGH A GOOD PORTION OF THE NIGHT. USED A BLEND OF MAV/MET/FWC MOS GUIDANCE TO GET LOWS IN THE LOW-MID 30S ACROSS SOUTHERN PORTIONS OF THE CWA AND UPPER 20S ACROSS THE INTERIOR. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... PRECIP WILL WIND DOWN AS A PERIOD OF SNOW BEFORE TAPERING OFF WITH MINOR ADDITIONAL ACCUMULATIONS. SKIES CLEAR OUT DURING THE AFTERNOON AS HIGH PRES MOVES INTO THE MID-ATLANTIC BY MIDDAY...THEN OFFSHORE MON NIGHT. A CLIPPER SYSTEM WILL MOVE ACROSS THE REGION ON TUE... MOVING OFFSHORE BY TUE NIGHT. WILL CONTINUE TO CARRY LIKELY POPS...AS THERE WEREN/T ANY MAJOR CHANGES THAT WERE NEEDED TO BE MADE TO THE PREVIOUS FCST. MODELS SEEM TO HAVE A GOOD HANDLE ON THIS UPCOMING SYSTEM. TEMPS WILL BE COLD ENOUGH TO SUPPORT SNOW THE THE NORTH...AND WARM ENOUGH FOR RAIN TO THE SOUTH. PRECIP WILL TAPER OFF AS ALL SNOW TUE NIGHT. WINTER WEATHER ADVISORIES MAY HAVE TO BE POSTED FOR ORANGE/PUTNAM/NORTHERN FAIRFIELD COUNTIES FOR TUE...AS OVER 3" SNOW COULD ACCUMULATE...BUT WILL WAIT FOR FCST TO BE REFINED. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... AS THE STORM HEADS OUT FARTHER INTO THE CANADIAN MARITIMES ON WED...THE TRAILING H5 TROUGH AXIS PASSES EAST. H8 FLOW IS WEAKLY CYCLONIC...SO MOST OF THE AREA SHOULD REMAIN DRY BUT WITH ABUNDANT INSTABILITY STRATOCU. EASTERN SECTIONS COULD SEE SOME SNOW SHOWERS AS DEEPER MOISTURE WRAPS AROUND THE BACK SIDE OF THE DEPARTING LOW. TEMPERATURES WILL BE ON THE COLD SIDE...DROPPING TO AROUND -12C TO -14C AT 925 MB IN THE AFTERNOON. IT MIGHT BE A DAY WHERE HIGHS OCCUR IN THE MORNING...PROBABLY REACHING ONLY 25-30. GUSTY NORTHWEST WINDS WILL MAKE IT FEEL EVEN COLDER...WITH WIND CHILLS DROPPING TO AROUND ZERO LATE WED NIGHT IN NYC....AND -5 TO -10 IN SOME INLAND SPOTS. RIDGING AT THE SURFACE AND ALOFT BEGINS TO BUILD IN ON THU. IT WILL BE MOSTLY SUNNY...BUT STILL COLDER THAN NORMAL. LOW LEVEL THICKNESSES SUPPORT EVEN COLDER HIGH TEMPS THAN THOSE OF WED... REMAINING IN THE 20S THROUGHOUT. THE CENTER OF THE HIGH WILL MOVE OFF THE MID ATLANTIC COAST ON FRI...WITH A DEVELOPING RETURN FLOW. MODERATION WILL BE SLOWER THAN MOS SUGGESTS ON FRI...WITH HIGHS IN THE 30S THROUGHOUT...BUT SHOULD KICK IN FOR SAT/SUN WITH HIGHS IN THE 40S...PERHAPS NEARING 50 IN NYC METRO ON SUN. A WARM FRONT PASSING TO THE NORTH/WEST COULD BRING THICKENING HIGH/MID LEVEL CLOUDS SAT NIGHT AND SUN...BUT LOW LEVELS WILL REMAIN QUITE DRY...SO NO PRECIP EXPECTED. NEXT CHANCE OF PRECIP APPEARS TO BE LATE SUN NIGHT WITH THE APPROACH OF A COLD FRONT. TEMPS SHOULD RUN AT LEAST SEVERAL DEGREES WARMER THAN MOS WITH SOUTHERLY FLOW AND CLOUD COVER...MAKING FOR AN ALL RAIN EVENT SUN NIGHT. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... CONDITIONS SHOULD DROP TO MVFR BY 01Z OR 02Z ACROSS WESTERN TERMINALS...02Z TO 03Z AT KISP...KBDR AND KGON. IFR/LIFR TO FOLLOW BETWEEN 03Z AND 06Z. LATEST ACARS SOUNDINGS ACROSS NYC INDICATE THAT THE GFS IS VERIFYING BETTER THAN THE NAM. THE WARM NOSE IN THE NAM IS ABOUT 2 DEGREES TOO HIGH AT 800 MB. THE RUC IS VERIFIES EVEN BETTER...BUT THIS IS TO BE EXPECTED SINCE IT USES ACARS SOUNDINGS IN IT. -SN IS EXPECTED TO BE THE DOMINANT P-TYPE AT KSWF BUT MAY BRIEFLY MIX WITH -IP AT TIMES THROUGH 09Z. LOOKING UPSTREAM...KMPO (AND KDXR) HAVE CHANGED TO FZRA OVER THE LAST HOUR. THIS IS BOTHERSOME AND INDICATES THAT WARMER AIR IS MOVING IN ALOFT. RUC INDICATES ABOUT A 3 HOUR PERIOD OF A WARM NOSE AT KSWF BETWEEN 04Z AND 07Z WHICH IS WHEN THERE COULD BE SOME IP MIXING IN...BUT IF THE WARM LAYER IS LARGER THAN THE PROFILE INDICATES WE COULD BE LOOKING AT PRECIP CHANGING TO FZRA. NOT CONFIDENT ENOUGH THAT THIS WILL OCCUR...SO HAVE NOT INCLUDED IN THE TAF. KJFK...KLGA...KEWR...KTEB AND KISP SHOULD ALL REMAIN RAIN FOR THE MAJORITY OF THE EVENT...BUT COULD CHANGE OVER TO -SN AT THE END (BETWEEN 09Z AND 12Z). SO ACCORDING TO THE RUC...THE REMAINING TERMINALS (KBDR...KGON AND KHPN)...WHICH WERE THE TOUGH ONES SINCE THEY REMAIN THE CLOSEST TO THE RAIN/SNOW LINE...ALL REMAIN -RA FOR MAJORITY OF THE EVENT AS WELL POSSIBLY CHANGING TO -SN AT THE END TOO. E/NE WINDS WILL GRADUALLY BACK TO THE N THEN NW AS THE COASTAL LOW PASSES TO THE SOUTH AND EAST LATE TONIGHT/EARLY MON MORNING. PRECIP SHOULD TAPER OFF FROM SW TO NE BETWEEN 12Z AND 15Z AND IT MAY NEED TO BE EXTENDED AN HOUR OR TWO LONGER THAN WHAT IS IN THE 00Z TAFS...BUT WILL WATCH RADAR AND ADJUST ACCORDINGLY. VFR CONDITIONS RETURN TO ALL TERMINALS BETWEEN 14Z AND 16Z WITH ONLY GUSTY NW WINDS TO CONTEND WITH. SUSTAINED WINDS SHOULD RANGE BETWEEN 12 AND 17KT WITH GUSTS BETWEEN 25 AND 30 KT. OUTLOOK FOR 00Z TUESDAY THROUGH THURSDAY...VFR REMAINS THROUGH MONDAY NIGHT. SUB-VFR CONDITIONS ARE AGAIN LIKELY TUESDAY AND TUESDAY EVENING AS AN ALBERTA CLIPPER LOW AND COLD FRONT PASS ACROSS THE AREA. RAIN NEAR THE COAST...RAIN/SNOW INTERIOR. THIS WILL BE FOLLOWED BY GUSTY W-NW FLOW LATER TUE NIGHT THROUGH THU AS THE OFFSHORE LOW INTENSIFIES AND DRAWS DOWN ARCTIC AIR. LIGHT SNOW SHOWERS OR FLURRIES WILL BE POSSIBLE ON WEDNESDAY...OTHERWISE DRY. && .MARINE... TODAY THROUGH TUESDAY NIGHT... SCA WILL BE UP FOR ALL WATERS STARTING THIS EVENING AS WIND GUSTS WILL BE OVER 25 KT...AND WAVES WILL BUILD TO 4-6 FT ON THE OCEAN. AFTER THE LOW DEPARTS ON MON...WEAK HIGH PRES WILL BUILD TO THE SOUTH. WITH A SHOT OF CAA...AND A TIGHT GRADIENT ON THE WATERS... THERE COULD BE OCNL GALE FORCE GUSTS DURING MON AFTERNOON. WILL CARRY STRONGLY WORDED SCA FOR NOW...AND LET MID SHIFT DECIDE IF GALES WILL BE MORE PREVALENT. THINK A GALE EVENT WILL BE MARGINAL AT BEST. FLAGS COME DOWN FROM WEST TO EAST MON EVENING...ENDING ON ALL WATERS BY MIDNIGHT. TRANQUIL CONDITIONS THEN EXPECTED THROUGH MIDDAY TUE. ANOTHER SYSTEM WILL BRING AT LEAST SCA CONDITIONS WITH GALES POSSIBLE ONCE AGAIN. DUE TO STRONGER CAA AND A STRONGER GRADIENT...THINK THERE WILL BE A BETTER CHANCE FOR GALES LATE TUE THAN LATE MON. WEDNESDAY THROUGH FRIDAY NIGHT... A STRONG PRESSURE GRADIENT AND LOW LEVEL CAA/INSTABILITY WILL COMBINE TO PRODUCE NW GALES ON THE OCEAN WED THROUGH THU MORNING...AND SCA CONDITIONS ELSEWHERE. SCA CONDITIONS ON THE OCEAN SHOULD COME TO AN END LATE THU NIGHT AS HIGH PRESSURE BUILDS OVER THE WATERS...BUT COULD RETURN TO THE EASTERN OCEAN WATERS FRI NIGHT VIA A STRENGTHENING WSW FLOW AS THE CORE OF THE HIGH PASSES OFF THE MID ATLANTIC COAST. && .HYDROLOGY... STORM SYSTEM TONIGHT IS EXPECTED TO PRODUCE 1/2 TO 3/4 INCH QPF THROUGH MON MORNING. SNOW AND SNOW/SLEET IS EXPECTED INLAND...AND RAIN THEN RAIN/SLEET/SNOW IS EXPECTED CLOSER TO THE COAST. ANOTHER SYSTEM ON TUE COULD PRODUCE UP TO 1/2" QPF ACROSS THE AREA. && .EQUIPMENT... KOKX WSR-88D IS FULLY OPERATIONAL...THOUGH A SOFTWARE/HARDWARE ISSUE WITH OUR AWIPS HAS CAUSED INTERRUPTIONS OF EXTERNAL DISSEMINATION. PLEASE CONTACT US IF YOU NOTICE THAT KOKX RADAR IS NOT AVAILABLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR CTZ005>008. NY...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR NYZ067>070. NJ...WINTER WEATHER ADVISORY UNTIL 9 AM EST MONDAY FOR NJZ002. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST MONDAY FOR ANZ335-338-355. SMALL CRAFT ADVISORY UNTIL 9 PM EST MONDAY FOR ANZ330-340-345. SMALL CRAFT ADVISORY UNTIL 11 PM EST MONDAY FOR ANZ350-353. && $$ SYNOPSIS...MPS NEAR TERM...MPS SHORT TERM...MPS LONG TERM...BG AVIATION...AL MARINE...BG/MPS HYDROLOGY...MPS ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 108 AM EST SUN DEC 30 2007 .SYNOPSIS... HIGH PRESSURE WILL BRIEFLY BUILD INTO THE REGION OVERNIGHT AND MOVE OFFSHORE SUNDAY. A LOW PRESSURE SYSTEM WILL DEVELOP ALONG THE SOUTHEAST COAST SUNDAY...AND TRACK NORTHEAST PASSING WELL SOUTH OF LONG ISLAND SUNDAY NIGHT. SNOW WILL OVERSPREAD THE AREA SUNDAY EVENING AND TAPER OFF MONDAY MORNING. HIGH PRESSURE WILL AGAIN ONLY BRIEFLY BUILD IN MONDAY NIGHT...THEN YET ANOTHER LOW PRESSURE SYSTEM WILL IMPACT THE REGION TUESDAY...BRINGING ACCUMULATING SNOW. THIS CLIPPER-TYPE SYSTEM WILL TRACK EASTWARD FROM THE GREAT LAKES TUESDAY WITH A MUCH COLDER AIRMASS BEING USHERED INTO THE REGION IN ITS WAKE. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... THE 13KM RUC SHOWS HIGH PRESSURE BUILDING IN FROM OHIO AT 0100 UTC. THE MID LEVEL FLOW CONTINUES TO FLATTEN...AS WELL AS THE THE LOW LEVEL FLOW IS VEERING TO A 270 DEGREE TRAJECTORY. THE KTYX RADAR SHOWS THE WEAK LAKE BAND SHIFTING SOUTHWARD OVER THE TUG HILL PLATEAU AND WRN ADIRONDACKS. THE BAND HAS NARROWED AND SHRUNK. THE LOWERING INVERSION TO 5 KFT PER THE KSYR BUFKIT NAM/GFS PROFILER SOUNDINGS INDICATE THIS ACTIVITY WILL WEAKEN TO ISOLD SNOW SHOWERS AND FLURRIES AFTER MIDNIGHT. WE LOWERED POPS TO VERY LOW CHANCE AND SLIGHT CHANCE FOR HERKIMER AND HAMILTON COUNTIES AFTER MIDNIGHT. THE CLOUDS LOOK TO PERSIST NORTH OF THE MOHAWK RIVER VALLEY AND CAPITAL REGION. WE WENT FROM MOSTLY CLOUDY/CLOUDY NORTH AND PARTLY CLOUDY/MOSTLY CLEAR TO THE SOUTH. WE RAISED TEMPS A FEW DEGREES OVER THE LAKE GEORGE REGION AND SRN VT WITH THE PERSISTENT CLOUDS. THE HOURLY T/TD/RH/WIND CHILL TRENDS WERE ALSO UPDATED. NO OTHER CHANGES AT THIS TIME. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY/... MODELS HAVE COME INTO AGREEMENT WITH THE DEVELOPMENT AND TRACK OF A COASTAL LOW FOR SUNDAY AND SUNDAY NIGHT. THE GFS AND NAM ARE IN FAIRLY GOOD AGREEMENT WITH THE GFS AND ECMWF IN VERY GOOD AGREEMENT. THE GFS IS A TAD DEEPER AND HAS THE MOST QPF. NORTHERN AND SOUTHERN STREAM ENERGY PHASE WITH THIS SYSTEM WITH DEVELOPMENT ALONG THE SOUTHEAST COAST SUNDAY. THE LOW DEEPENS AND PASSES WELL SOUTH OF LONG ISLAND SUNDAY NIGHT. WITH SYSTEM SO FAR OFFSHORE SINGLE P-TYPE OF SNOW. UPPER SYSTEM IS OPEN AND PROGRESSIVE...SO A QUICKER SHOT. LIGHT SNOW WILL OVERSPREAD THE AREA SUNDAY EVENING WITH THE HEAVIEST SNOW AFTER MIDNIGHT AND TAPERING OFF MONDAY MORNING. USED HPC QPF GUIDANCE AND TWEAKED IT SOME BETWEEN 06-12Z. AT THIS TIME HAS POSTED A SNOW ADVISORY FOR ULSTER...DUTCHESS AND LITCHFIELD COUNTIES FOR SUNDAY NIGHT FOR 3 TO 6 INCHES. THERE IS A CHANCE THE SNOW ADVISORY MAY NEED TO BE EXPANDED FARTHER NORTH...BUT IT IS A THIRD PERIOD ADVISORY AND POSTED IT WHERE HAVE THE HIGHEST CONFIDENCE. AGAIN RIDING BUILDS IN BRIEFLY MONDAY AFTERNOON AND NIGHT...BETWEEN SYSTEMS. CLIPPER SYSTEM WILL MOVING EASTWARD FROM THE GREAT LAKES REGION TUESDAY BRINGING ANOTHER ROUND OF ACCUMULATING SNOW TO THE AREA. THERE IS THE POSSIBILITY WILL NEED SNOW ADVISORIES FOR PORTIONS OF THE FORECAST BUT IT IS MUCH TO EARLY. SOUTHERN STREAM ENERGY INITIATES LOW DEVELOPMENT AND NORTHERN STREAM ENERGY DIVES OUT OF CANADA AND DIGS DEEP TROUGH ACROSS THE EASTERN UNITED STATES. THIS WILL BRING A MUCH COLDER AIRMASS INTO THE REGION. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... RELATIVELY QUIET PERIOD WEATHER WISE IN TERMS OF ADDITIONAL LOW PRESSURE SYSTEMS MOVING THROUGH THE FORECAST AREA. INITIALLY...THE REGION WILL BE DOMINATED BY A VERY COLD AIRMASS THAT SURGES INTO THE REGION TUESDAY NIGHT THROUGH WEDNESDAY NIGHT ON STRONG NORTHWEST WINDS BEHIND A LOW PRESSURE SYSTEM OVER THE CANADIAN MARITIMES. THIS FLOW WILL RESULT IN A TYPICAL CYCLONIC FLOW/LAKE EFFECT WEATHER PATTERN FOR ABOUT 36 HOURS BEFORE THE HIGH PRESSURE RIDGE MOVES OVER THE REGION THURSDAY. PROGRESSIVELY COLDER AIR WILL LEAD TO WEDNESDAY NIGHT AND THURSDAY BEING THE COLDEST NIGHT AND DAY WE WILL HAVE HAD IN A COUPLE OF WEEKS ACROSS THE REGION. LOWS WEDNESDAY NIGHT WILL BE 10 BELOW TO 10 ABOVE WITH A DECENT NORTHWEST WIND MOST OF THE NIGHT. HIGHS THURSDAY WILL ONLY BE IN THE TEENS TO LOWER 20S. STILL QUIET PCPN WISE FRIDAY INTO SATURDAY WITH A WARMING TREND EXPECTED. BY SATURDAY HIGH WILL BE IN THE MID 20S TO MID 30S. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... HIGH PRESSURE CONTINUES TO BUILD IN FROM THE OHIO VALLEY TONIGHT. THIS HIGH WILL BE IN CONTROL THE NEXT 18-24 HOURS...BEFORE AN AREA OF LOW PRESSURE WILL BE CLOSE ENOUGH TO THE ATLANTIC/NEW ENGLAND SEABOARD TO PRODUCE SOME SNOW/SLEET ACROSS MUCH OF ERN NY SUNDAY NIGHT INTO MONDAY MORNING. VFR CONDITIONS WILL DOMINATE THE NEXT 18 HOURS...EXCEPT FOR MVFR/IFR AT KPOU EARLY THIS MORNING WHERE FOG HAS ALREADY DEVELOPED. MOIST CYCLONIC FLOW ALOFT WILL KEEP SOME BKN-OVC SKY COVER FROM KALB NORTH TO KGFL WITH CIGS IN THE 4-6 KFT AGL RANGE WITH ONLY SCT CLOUDS PERSISTING SOUTH OF ALBANY. THE CLOUDS WILL THICKEN IN THE AFTERNOON WITH THE APPROACHING LOW FROM THE SOUTH. EXPECT BKN-OVC MID LEVEL CLOUDINESS AT 10-15 KFT AFTER 20Z...WITH SNOW ADVANCING FROM SOUTH TO NORTH STARTING AT KPOU AROUND 23Z...KALB AROUND 01Z AND KGFL AROUND 04Z. SOME SLEET MAY MIX IN AT THE START AT KPOU AND ONCE PCPN STARTS CONDITIONS WILL QUICKLY DETERIORATE TO IFR/LIFR. AS FOR WINDS...GENERALLY LIGHT AND VARIABLE BECOMING NORTHEAST LATE TODAY AT 4-6 KTS. OUTLOOK... SUN NIGHT-MON AM...IFR/MVFR CIGS/VSBYS WITH SN MAINLY KALB SOUTH. MON PM...VFR. TUE...VFR/MVFR CIG IN -SN WED...VFR...WDLY SCT -SHSN. THU...VFR...NO SIG WX. && .HYDROLOGY... WE ARE NOT EXPECTING ANY HYDROLOGICAL ISSUES ON THE MAIN STEM RIVERS THROUGH THE NEXT SEVEN DAYS. MOST IF NOT ALL PCPN EXPECTED THROUGH NEXT SATURDAY WILL BE IN THE FORM OF SNOW. AFTER THIS AFTERNOON... SNOW MELT WILL BE MINIMAL AND MOSTLY CONFINED TO SOUTHERN VALLEY LOCATIONS. IN THE WAKE OF THE CLIPPER TYPE SYSTEM TUESDAY...THE MIDDLE OF THE WEEK LOOKS VERY COLD WHICH WILL START TO BUILD ICE AGAIN ON AREA RIVERS AND STREAMS. $$ && .ALY WATCHES/WARNINGS/ADVISORIES... CT...SNOW ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST MONDAY FOR CTZ001-013. NY...SNOW ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST MONDAY FOR NYZ063>066. MA...NONE. VT...NONE. && $$ AVIATION...11 ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TAUNTON MA 1239 AM EST SAT DEC 29 2007 .SYNOPSIS... LOW PRES WILL MOVE TO SW QUEBEC EARLY SAT. SECONDARY LOW PRES WILL PASS ACROSS SOUTHERN NEW ENGLAND SAT MORNING...AND BECOME THE DOMINANT CENTER OVER THE MARITIMES BY SAT NIGHT. HIGH PRES WILL PASS OVER THE REGION ON SUN. A COASTAL LOW WILL INTENSIFY OFF THE MID ATLANTIC COAST SUN NIGHT AND PASS SE OF NANTUCKET ON MON MORNING. THIS LOW HAS THE POTENTIAL TO BRING SIGNIFICANT SNOWFALL TO MUCH OF SOUTHERN NEW ENGLAND SUN NIGHT INTO MON. A SERIES OF COLD FRONTS WILL USHER COLDER AIR WED AND THU. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... 18Z MODELS NOT DOING A GREAT JOB HANDLING INITIAL BURST OF RAIN WORKING THROUGH EASTERN PA AT 9 PM...EVEN 01Z 13KM RUC IS A LITTLE SLOW. CURRENT TIMING INTO CT RIVER VALLEY JUST AFTER MIDNIGHT AND TO COASTAL PLAIN BY 3 AM LOOKS REASONABLE...DESPITE PLENTY OF DRY AIR TO OVERCOME AT MID LEVELS PER 00Z SOUNDINGS. 00Z NAM TIMING IS A BIT BETTER BUT PROBABLY STILL A LITTLE SLOW. PRECIPITATION TYPE CONTINUES TO BE MAIN CONCERN OVERNIGHT FOR NORTHERN ZONES. TEMPERATURES HAVE MANAGED TO DROP OFF THIS EVENING DESPITE FAIRLY THICK CLOUD COVER...WITH MANY LOCATIONS IN UPPER 20S AND LOWER 30S AT 9 PM. WARMING WILL BEGIN TO TAKE PLACE AS STRONG WARM ADVECTION GETS UNDERWAY AT AT LEVELS...BUT SOME OF SHELTERED AND DEEPER VALLEYS WILL BE LAST TO WARM UP. WE USED 18Z NAM PARTIAL THICKNESSES WHICH BETTER REFLECT THIS LOW LEVEL COLD BUT OVERALL RESULT IS SIMILAR TO AFTERNOON FORECAST...IF ANYTHING A LITTLE LESS SNOWFALL WHICH IS ALSO SUPPORTED BY LATEST SREFS AND MODEL FORECAST SOUNDINGS. WE THINK MOST AREAS NORTH OF I-90 WILL START OUT AS A SNOW/SLEET MIX AND QUICKLY TRANSITION TO SLEET/FREEZING RAIN. CORRIDOR BETWEEN I-90 AND ROUTE 2 SHOULD CHANGE TO RAIN WITHIN A COUPLE OF HOURS OF ONSET... WHILE IT PROBABLY TAKES UNTIL SUNRISE SAT FOR OUR SW NH ZONES TO WARM UP ENOUGH FOR A CHANGE TO RAIN. THIS MEANS WE EXPECT AN INCH OR TWO OF SNOWFALL AT MOST IN FAR SW NH WITH A LIGHT COATING /0.10/ OF ICE. WE DO NOT THINK THERE WILL BE MUCH IF ANY ICING ACROSS NORTHERN MA...SO ADVISORY WILL NOT BE EXPANDED INTO THOSE AREAS. OTHER ISSUE OVERNIGHT WILL BE INCREASING SOUTHERLY WINDS AROUND CAPE COD AND ISLANDS. 18Z MODELS...ESPECIALLY NAM...SHOW VERY STRONG LOW LEVEL JET OF NEARLY 80KT REACHING SE COAST BY 12Z SAT. WHILE A STRONG INVERSION WILL PREVENT MOST OF THIS FROM GETTING DOWN TO SURFACE... AND NAM MAY BE SLIGHTLY OVERDONE...POTENTIAL EXISTS FOR BORDERLINE WIND ADVISORY CRITERIA SAT MORNING. WE DO NOT HAVE ENOUGH CONFIDENCE TO ISSUE ONE JUST YET...BUT WE WILL REASSESS WITH 00Z MODEL DATA. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM SUNDAY/... RAIN MAY BE HEAVY AT TIMES THROUGH MID MORNING BEFORE LOW PRESSURE PASSES BY CAPE COD. SECONDARY LOW PRESSURE CENTER SHOWN ON ALL MODELS TO BE IN INCIPIENT STAGE OF DEVELOPMENT PASSING ACROSS SOUTHERN NEW ENGLAND...BUT BECOMING THE DOMINANT SYSTEM AS IT APPROACHES THE MARITIMES SAT EVENING. DOWNSLOPING WNW FLOW BEHIND THIS SYSTEM SHOULD HELP CLEAR SKIES SAT AFTERNOON. DOWNSLOPING WIND AND RESIDUAL WARM TEMPS ALOFT SHOULD SUPPORT MILD TEMPS SAT AFTERNOON...EVEN WITH COLD AIR ADVECTION BEGINNING TO SET IN. THE COLD AIR ADVECTION BECOMES NOTICEABLE SAT NIGHT AS TEMPS SHOULD DROP FAIRLY QUICKLY. THIS SHOULD PUT IN PLACE SUFFICIENTLY COLD AIR TO SET THE STAGE FOR THE NEXT SYSTEM SUN NIGHT. MAVMOSGUIDE LOOKED REASONABLE FOR SAT NIGHT LOWS. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... A PLOWABLE SNOW EVENT LIKELY FOR A PORTION OF THE REGION SUN NIGHT INTO MON WITH THE POTENTIAL FOR A SIGNIFICANT SNOW ACCUMULATION. SUNDAY THROUGH MONDAY... OPERATIONAL GFS/UKMET/CANADIAN GGEM AND THE UKMET ALL COMING INTO BETTER AGREEMENT REGARDING INCREASED CHANCES FOR ACCUMULATING SNOWFALL ACROSS MUCH OF THE REGION SUNDAY NIGHT THROUGH MONDAY MORNING. RECENT OPERATIONAL TRENDS BRING THE SURFACE LOW TRACK CLOSER TO THE COAST. HOWEVER THERE IS STILL SOME UNCERTAINTY WITH RESPECT TO THE TIMING OF PRECIPITATION AS WELL ACTUAL LOW TRACK. THE 12Z NAM AND 09Z SREF RUNS WERE TRACKING A WEAKER LOW TO THE SOUTH OF THE REGION. IN ADDITION THE GFS ENSEMBLES INDICATED 4 OF ITS 12 MEMBERS FAVORING THIS SCENARIO. OVERALL THE LOW TRACK AND INTENSIFICATION WILL DEPEND ON THE STRENGTH AND TIMING OF A PACIFIC JET STREAK WHICH WILL ATTEMPT TO INTERSECT WITH A SECOND JET STREAK ENTERING THE NORTHEAST ALLOWING SURFACE LOW PRESSURE TO INTENSIFY. IN ADDITION SIGNIFICANT GULF AND ATLANTIC MOISTURE WILL BE AVAILABLE. GIVEN SOME UNCERTAINTY AMONGST MODEL RUNS DECIDED USE A MODEL BLEND SIMILAR TO HPC. OVERALL DECIDED RAISE POPS TO LIKELY GIVEN RECENT TRENDS AND DECENT CONSENSUS AMONGST MOST OF THE OPERATIONAL MODEL GUIDANCE AND ENSEMBLES. CURRENT THERMAL PROFILES FAVOR MOSTLY SNOW...BUT SOME RAIN AND SLEET COULD MIX IN ACROSS THE CAPE AND ISLANDS GIVEN SOME STRENGTHENING ONSHORE FLOW AND WARM AIR ADVECTION. REVIEWED THE LATEST HPC WINTER WEATHER DESK GRAPHIC AND COLLABORATED WITH SURROUNDING OFFICES. STRONG OMEGA AND MID LEVEL FRONTOGENETIC FORCING WITHIN THE LOWS DEFORMATION ZONE COULD YIELD A BAND OF LOCALLY HEAVY SNOWFALL WITHIN THE FORECAST AREA. WILL HIGHLIGHT THE CONCERNS IN THE HAZARDOUS WEATHER OUTLOOK. STAY TUNED. MONDAY NIGHT THROUGH FRIDAY... A SERIES OF SHORT WAVE DISTURBANCES WILL BRING A CHANCE FOR SNOW OR SNOW SHOWERS MONDAY NIGHT THROUGH WEDNESDAY BEFORE SURFACE HIGH PRESSURE BUILDS WITH PROGRESSIVELY COLDER AIR WEDNESDAY INTO THURSDAY. MAIN TIMEFRAME OF CONCERN WILL BE TUESDAY AND TUESDAY NIGHT AS A COLD FRONT CROSSES THE REGION. THE ECMWF REMAINS LEAST PROGRESSIVE REGARDING THE ARRIVAL OF AN UPPER LEVEL TROUGH AND COLDER AIR FROM THE MIDWEST WHILE THE GFS IS A BIT MORE PROGRESSIVE. CURRENTLY DECIDED TO CONTINUE THE CHANCE OF SNOW TUESDAY AND TUESDAY NIGHT GIVEN THE NEARBY COLD FRONT AND POTENTIAL INVERTED TROUGH SIGNATURE. ADDITIONAL OCEAN EFFECT SNOW SHOWERS WILL BE POSSIBLE ACROSS THE CAPE AND ISLANDS LATE WEDNESDAY AND THURSDAY IN COLD NORTH TO NORTHWEST FLOW. STAYED FAIRLY CLOSE TO HPC/MOS GUIDANCE. VERY COLD WIND CHILLS FROM THE NEGATIVE TO POSITIVE SINGLE NUMBERS POSSIBLE LATE WEDNESDAY INTO THURSDAY. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... FIRST BATCH OF LIGHT RAIN MOVING THROUGH SOUTHERN NEW ENGLAND WILL MAINTAIN VFR CONDITIONS AT MOST TERMINALS...THOUGH CEILINGS MAY LOWER TO MVFR NORTH OF I-90. TEMPERATURES HAVE BEGUN TO WARM AND ICING THREAT APPEARS TO BE MINIMAL THROUGH 12Z...ASIDE FROM SOME OF THE SHELTERED INTERIOR VALLEYS WHERE A BRIEF PERIOD OF -FZRAPL IS STILL POSSIBLE. NEXT BATCH OF RAIN WAS HEADING INTO METRO NYC AT 0530Z AND WILL REACH CT VALLEY TERMINALS BY 08Z AND COASTAL LOCATIONS BY 09Z. THIS WILL LOWER CONDITIONS TO IFR OVER MUCH OF AREA THROUGH 15Z OR SO...BEFORE CONDITIONS IMPROVE RAPIDLY TO VFR AROUND 18Z. STRONG S/SE WINDS WILL BE AN ISSUE AT KHYA/KACK FROM 10Z-15Z WHEN LLWS IS EXPECTED FROM A 65KT LOW LEVEL JET. WE PLAYED IT A LITTLE CONSERVATIVE FOR GUSTS GIVEN STRONG INVERSION IN PLACE /32KT/... SO THERE IS A LOW PROBABILITY OF REACHING 40KT GUSTS THIS MORNING. CLEARING SETS IN THIS AFTERNOON WITH DIMINISHING W/NW WINDS. SUNDAY THROUGH TUESDAY... SUNDAY...VFR SUN NIGHT AND MON...MVFR WITH POSSIBLE AREAS OF IFR IN SNOW. SLEET OR RAIN COLD MIX IN ALONG THE SOUTH COAST. NE WIND GUSTS TO 30-40 KT POSSIBLE ACROSS CAPE COD AND NANTUCKET ISLAND. MON NIGHT...VFR. TUE...MVFR WITH POSSIBLE SNOW SHOWERS. && .MARINE... RESIDUAL 5 TO 7 FT NE SWELL PERSISTS ON OUTER SE WATERS THIS EVENING. GALE WARNINGS REMAIN POSTED FOR MOST OF WATERS NEAR CAPE COD...ESPECIALLY S AND E. NAM 18Z RUN LOOKS A LOT BEEFIER ON LOW LEVEL JET...SHOWING 75 TO 80 KT. ALTHOUGH LATEST GFS RUN STILL AT 60 KT...BOTH NAM AND GFS BUFKIT SOUNDINGS NOW SHOWING AT LEAST MARGINAL GALE AT OR VERY NEAR SFC. IF MIXING HEIGHT STILL TOO LOW TO SUPPORT SUFFICIENT MOMENTUM TRANSFER...BELIEVE WE WILL LIKELY SEE IT WITH HEAVIER SHOWER ACTIVITY. GLW PLACED NEAR LOW LEVEL JET CORE AND AXIS OF GREATEST INSTABILITY. SCA CONTINUES ELSEWHERE EXCEPT FOR BOSTON HARBOR FOR LATE TONIGHT INTO SAT. BELIEVE NARAGANSETT BAY SCA WIND GUSTS WILL BE JUST MAINLY 08Z TO 16Z TIME FRAME. OVER MOST OF THE REST OF THE WATERS...SEAS AND W WIND GUSTS SAT AND EVE SHOULD KEEP HEADLINE GOING LONGER. SUNDAY...WINDS AND SEAS DIMINISH AS HIGH PRESSURE BUILDS ACROSS THE WATERS. SUNDAY NIGHT AND MONDAY... NE GALES MAY OCCUR. RAISED WNA GUIDANCE ABOUT 2-3 FT. MONDAY NIGHT AND TUE... WINDS AND SEAS BRIEFLY DIMINISH. TUESDAY NIGHT THROUGH WED... SMALL CRAFT ADVISORY NW WIND GUSTS TO 25 KT WITH POSSIBLE GALES BY LATE WED. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR NHZ011- 015. RI...NONE. MARINE...GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR ANZ232-254-255. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR ANZ231- 233>235-237-250. SMALL CRAFT ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR ANZ236. && $$ SYNOPSIS...STRAUSS/THOMPSON NEAR TERM...JWD SHORT TERM...THOMPSON LONG TERM...STRAUSS AVIATION...JWD MARINE...JWD ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 300 PM EST SUN DEC 30 2007 ...STRONG ARCTIC COLD FRONT TUESDAY WILL BRING MUCH COLDER AIRMASS TO THE REGION FOR THE MID-WEEK PERIOD ALONG WITH AN EXTENDED PERIOD OF ADVISORY LEVELS CONDITIONS OVER THE COASTAL WATERS... .SYNOPSIS... 19Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING UPPER AIR PATTERN ACROSS THE CONUS CONTINUES DOMINATED BY LONG WAVE TROUGHING WITH AN AXIS ROUGHLY NORTH/SOUTH ALONG THE MISSISSIPPI RIVER VALLEY. FORECAST AREA SEEING PLENTY OF HIGH/MID LEVEL SOUTHERN STREAM MOISTURE ADVECTING NORTHWARD IN ADVANCE OF THIS TROUGH. STRONG MID LEVEL SHORTWAVE CONTINUES TO APPROACH FROM THE WEST AS IT ROUNDS THE BASE OF THE TROUGH THROUGH THE LOWER MISSISSIPPI VALLEY. MARKED DRYING ON EARLY AFTERNOON WV IMAGERY OVER TX/LA/MS SHOWS THIS SHORTWAVE REMAINS A FAIRLY POTENT PIECE OF ENERGY. AT THE SURFACE...WEAK COLD FRONT RUNNING FROM THE WESTERN FL PANHANDLE...INTO SOUTHEAST ALABAMA AND THEN NORTHEAST TO THE CAROLINAS. SHOWERS AND THUNDERSTORMS HAVE BEEN QUITE WIDESPREAD THROUGH THE MIDDLE AFTERNOON ALONG AND AHEAD OF THIS FRONT. STILL A SMALL CHANCE FOR ONE OR TWO OF THE STORM TO BECOME STRONG AND POTENTIALLY MARGINALLY SEVERE AS ATMOSPHERIC SHEAR PROFILES ARE FAVORABLE FOR ORGANIZED CELLS. WOULD APPEAR THAT THERE WILL ONLY BE A BRIEF WINDOW DURING THE LATE AFTERNOON WHEN THE MID/UPPER LEVEL DYNAMICS/THERMODYNAMICS ASSOCIATED WITH THE SHORTWAVE WILL BE MAXIMIZED. ANY SEVERE THREAT SHOULD THEN DIMINISH RAPIDLY INTO THE EARLY EVENING HOURS AS THE BEST SYNOPTIC LIFT MOVES NORTHEAST INTO THE CAROLINAS. && .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT. MAIN DEEP LAYER (700-300MB) Q-G FORCING AND BEST UPPER LEVEL JET DYNAMICS EXIT RAPIDLY TO THE NORTHEAST THIS EVENING WITH THE SHORTWAVE BRING AN END TO THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS. EVEN STILL...LOW LEVEL CONVERGENCE ALONG THE EASTWARD PROPAGATING FRONTAL BOUNDARY COMBINED WITH SOME WEAK SYNOPTIC FORCING ASSOCIATED WITH THE LARGER SCALE TROUGH SHOULD STILL KEEP SCATTERED SHOWERS AND A FEW ISOLATED WEAKER THUNDERSTORMS GOING INTO THE EVENING HOURS. TAPERING POPS FOR A SLIGHT CHANCE AROUND THE APALACHICOLA RIVER TO CHANCE 30-45 POPS FURTHER EAST TOWARD THE SUWANNEE RIVER VALLEY. AFTER MIDNIGHT JUST A SLIGHT CHANCE OF A FEW LINGERING LIGHT SHOWERS TOWARD TAYLOR...DIXIE...AND LAFAYETTE COUNTIES...BUT ESSENTIALLY THE RAINFALL SHOULD BE OVER. A BIT COOLER TONIGHT WITH TEMPS RANGING FROM THE LOWER TO MIDDLE 50S OVER THE EASTERN BIG BEND TO THE LOWER AND MIDDLE 40S OVER THE FAR WEST. PARTIAL CLEARING WILL ALSO PUSH EAST THROUGH THE NIGHT WITH ONLY THE FAR SOUTHEAST BIG BEND STILL MOSTLY CLOUDY BY SUNRISE MONDAY. HIGH PRESSURE BUILDS OVERHEAD DURING MONDAY WITH FAIR AND DRIER WEATHER. SEASONABLE TEMPS EXPECTED WITH HIGHS CLIMBING INTO THE LOWER AND MIDDLE 60S NORTH AND MIDDLE AND UPPER 60S SOUTH. NORMALLY WARMER SPOTS TOWARD THE SOUTHEAST BIG BEND MAY EVEN REACH THE LOWER 70S DEPENDING ON DEGREE OF CLOUDCOVER (CLEARING LINE WILL BE IN THE VICINITY). ATTENTION THEN TURNS MONDAY NIGHT TO DEEP TROUGHING DIGGING SOUTH ACROSS MID-SECTION OF THE COUNTRY. ASSOCIATED STRONG ARCTIC COLD FRONT WILL APPROACH FROM THE NORTHWEST DURING THE NIGHT CROSSING THROUGH OUR FORECAST AREA DURING THE MORNING HOURS. AT THIS TIME...EXPECTING A DRY FRONTAL PASSAGE...MOST LIKELY JUST A BRIEF BAND OF CLOUDS. FRONT WILL PASS LATE ENOUGH THAT TEMPERATURES WILL NOT FALL MUCH BELOW CLIMO NORMS WITH UPPER 30S TO NEAR 40 NORTH TO MIDDLE 40S SOUTH. HOWEVER...LOW TEMPS TUESDAY MORNING WILL HIGHLY DEPEND ON THE EXACT FRONTAL TIMING...AS EVEN A FEW HOURS WILL MAKE A DIFFERENCE. RIDGING BEGINS TO BUILD IN AT THE SURFACE BEHIND THE FRONT AS DEEP AND MID/UPPER LEVEL TROUGHING TAKES CONTROL OF THE EASTERN U.S. DESPITE ACTUAL TEMPS REACHING INTO THE MIDDLE 50S TO LOWER 60S NORTH TO SOUTH TUESDAY...GUSTY NORTHWEST WINDS BETWEEN 15 AND 25 MPH WILL MAKE THIS FEEL COOLER. THIS WILL BE THE COLDEST AIRMASS OF THE SEASON THUS FAR WITH 850MB TEMPS FALLING FROM BETWEEN +6-10C EARLY TUESDAY MORNING TO -5 TO -10C LATER TUESDAY EVENING. THE COLD AIR ADVECTION WILL REALLY BEING TO BE FELT ACROSS THE AREA TUESDAY EVENING WITH TEMPERATURES FALLING RAPIDLY THROUGH THE 40S AND 30S. GOOD CHANCE FOR A WIDESPREAD FREEZE TUESDAY NIGHT INTO EARLY WEDNESDAY MORNING WITH MIDDLE AND UPPER 20S COMMON. CURRENT GRIDS ARE ACTUALLY ABOUT 3 DEGREES WARMER THAN GUIDANCE WHICH KEEPS US OUT OF HARD FREEZE CRITERIA. BUMPED TEMPS UP A FEW DEGREES SINCE THE MAV HAS HAD A COOL BIAS SO FAR THIS WINTER SEASON WITH ITS LOWS. && .LONG TERM...WED THROUGH SUN. STRONG CAA PATTERN CONTINUES WEDNESDAY AS SHARP UPPER TROUGH DIGS INTO THE DEEP SOUTH AND 1045+MB HIGH PRESSURE DROPS INTO THE CENTRAL PLAINS. FREEZING TEMPS EXPECTED BY WEDNESDAY MORNING WITH HARD FREEZE POSSIBLE OVER SOUTH GEORGIA. TEMPS WILL STRUGGLE TO REACH 50 DEGREES WEDNESDAY AFTERNOON LEADING INTO THE COLDEST NIGHT OF THE SEASON SO FAR. SFC HIGH WILL BE LOCATED NORTH OF THE AREA WEDNESDAY NIGHT...NOT THE IDEAL POSITION FOR RADIATIONAL COOLING...BUT THE GRADIENT SHOULD RELAX ENOUGH TO ALLOW TEMPS TO PLUMMET IN THE COLD AND DRY AIRMASS. GUIDANCE STILL CALLING FOR HARD FREEZE FOR ALL BUT THE IMMEDIATE COAST BY THURSDAY MORNING. THEREAFTER...AIRMASS WILL GRADUALLY MODIFY AS SFC HIGH PARKS OVER THE WESTERN ATLANTIC AND UPPER FLOW BECOMES MORE ZONAL. MAY SEE A LIGHT FREEZE AGAIN FRIDAY MORNING BEFORE EASTERLY FLOW MOISTENS THINGS UP AND WARMS TEMPS UP. EASTERLY FLOW THROUGH NEXT WEEKEND WILL MOISTEN UP THE LOW LEVELS...BUT WITH BUILDING RIDGE ALOFT...DO NOT ANTICIPATE SIGNIFICANT RAIN CHANCES ATTM. && .MARINE... WEAK COLD FRONT WILL SLOWLY PUSH EAST ACROSS THE COASTAL WATERS THROUGH THIS EVENING WITH WIND NEAR CAUTION LEVELS COMING AROUND FROM THE SOUTH TO THE NORTHWEST BEHIND THE BOUNDARY. FLOW BECOMES NORTHERLY ACROSS ALL AREAS BY LATE TONIGHT AS THE FRONT SETTLES SOUTH OF THE AREA. WILL SEE FLOW WEAKEN BRIEFLY DURING MONDAY AND MONDAY EVENING BEFORE A STRONG COLD FRONT APPROACHES FROM THE NORTHWEST EARLY TUESDAY MORNING. WINDS AND SEAS WILL INCREASE RAPIDLY FROM THE NORTHWEST TO ADVISORY LEVELS TUESDAY MORNING AND REMAIN AT OR ABOVE ADVISORY CRITERIA INTO AT LEAST WEDNESDAY. WINDS MAY EVEN APPROACH GALE FORCE...AT LEAST IN GUSTS INTO EARLY WEDNESDAY. WINDS AND SEAS ARE EXPECTED TO DROP BELOW ADVISORY LEVELS ON THURSDAY AS HIGH PRESSURE BUILDS TO THE NORTH. && .AVIATION... NUMEROUS SHRA AND ISOLATED TSRA WILL CONTINUE ACROSS THE REGION THIS AFTERNOON...THEN TAPER OFF FROM WEST TO EAST THIS EVENING AS THE COLD FRONT MOVES THROUGH. WIDESPREAD MVFR CIGS WILL OCCUR THROUGH THIS EVENING...WITH OCCASIONAL IFR TO VLIFR CIGS/VIS IN SHOWERS. CIGS WILL IMPROVE TO VFR FROM NORTHWEST TO SOUTHEAST TONIGHT. WIND GUSTS TO 25 KT ARE POSSIBLE IN THE STRONGER STORMS THIS AFTERNOON. && .FIRE WEATHER... COLD FRONT WILL SLOWLY PUSH EAST THROUGH THE REGION THIS EVENING AND OVERNIGHT. THIS WILL END THE CHANCES FOR SHOWERS FOR ALL AREAS BY MONDAY MORNING WITH HIGH PRESSURE AND SOMEWHAT DRIER AIR FILTERING IN. DESPITE THE DRIER AIR...RELATIVE HUMIDITY VALUES ARE EXPECTED TO REMAIN ABOVE CRITICAL LEVELS THROUGH MONDAY NIGHT. A MUCH STRONGER COLD FRONT WILL PASS THROUGH THE REGION EARLY TUESDAY BRINGING WITH IT A MUCH COLDER AND VERY DRY AIRMASS TO THE SOUTHEAST. A FIRE WX WATCH HAS BEEN ISSUED FOR ALL OF THE EASTERN FL PANHANDLE AND FLORIDA BIG BEND FOR TUESDAY AFTERNOON FOR A COMBINATION OF DURATIONS OF RH BELOW CRITICAL LEVELS ALONG WITH ELEVATED SURFACE WINDS. ALTHOUGH IT WILL BE QUITE DRY FOR SOUTHEAST AL/SOUTHWEST GA...TEMPERATURES SHOULD BE COOL ENOUGH ON TUESDAY TO PREVENT CRITICAL VALUES OF RELATIVE HUMIDITY FROM BEING REACHED...HOWEVER IT WILL NEED TO BE MONITORED CLOSELY. FIRE WX CONCERNS FOR CONTINUE INTO WEDNESDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 49 69 41 60 27 / 40 05 05 0 0 PANAMA CITY 49 67 43 59 30 / 20 00 05 0 0 DOTHAN 42 66 39 54 26 / 15 00 10 0 0 ALBANY 44 67 40 55 26 / 25 00 10 0 0 VALDOSTA 51 68 41 60 27 / 40 05 05 0 0 CROSS CITY 55 73 46 65 28 / 45 10 05 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...FIRE WEATHER WATCH TUESDAY AFTERNOON FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN...GADSDEN...GULF... HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE... LEON...LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION...FOURNIER PUBLIC/MARINE/FIRE WX...MROCZKA LONG TERM...CAMP fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 225 PM EST SAT DEC 29 2007 .SYNOPSIS... 19Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING MOST OF THE CONUS UNDER THE INFLUENCE OF A LONG WAVE TROUGH WITH AN AXIS FROM THE NORTHERN PLAINS TO WEST TEXAS. THIS TROUGH HAS TAPPED INTO THE SOUTHERN STREAM WITH PLENTY OF MID/HIGH LEVEL MOISTURE PUMPING UP ON THE EASTERN SIDE FROM THE WESTERN GULF OF MEXICO TO THE SOUTHEASTERN STATES. AT THE SURFACE...NEARLY STATIONARY BOUNDARY IS ANALYZED FROM THE WESTERN FL PANHANDLE SOMEWHERE AROUND SE AL/SW GEORGIA AND THEN CONTINUING NORTHEAST. THIS BOUNDARY HAS BEEN THE FOCUS FOR NUMEROUS SHOWERS AND EMBEDDED THUNDERSTORMS TODAY ACROSS THE NORTHWEST HALF OF THE FORECAST AREA. FURTHER SOUTH AND EAST THE SHOWERS HAVE BEEN ISOLATED IN NATURE WITH FOG BEING THE BIGGER CONCERN. BREAKS OF SUN HAVE BEEN ABLE TO DEVELOP IN THE LOW CLOUDS WITH MUCH OF THE FOG LIFTING THIS EARLY AFTERNOON. HOWEVER...WITH THE SETTING OF THE SUN...THE FOG IS VERY LIKELY TO RETURN. FOR THE REST OF THE AFTERNOON...EXPECT THE NORTHWEST PORTION OF THE FORECAST AREA TO CONTINUE TO SEE SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS. FROM KAAF...TO KTLH...TO KVLD SOUTH AND EAST THE SHOWERS WILL BE VERY ISOLATED IN NATURE AND SHOULD GENERALLY REMAIN DRY INTO THE EVENING HOURS. && .SHORT TERM...TONIGHT THROUGH MONDAY NIGHT. MAIN UPPER TROUGH AXIS BEGINS TO SHIFT EASTWARD OVERNIGHT FROM THE SOUTHERN PLAINS WITH A PIECE OF ENERGY ROUNDING THE BASE INTO THE CENTRAL GULF COAST LATE. DEEP LAYER Q-G FORCING ON THE EASTERN SIDE OF THE TROUGH WILL COMBINE WITH UPPER DIVERGENCE IN THE RIGHT REAR QUADRANT OF A 150-170KT UPPER JET TO PRODUCE PLENTY OF SYNOPTIC FORCING (ESPECIALLY LATE TONIGHT AND DURING SUNDAY MORNING). ALSO GFS/NAM SHOWING AN INCREASINGLY STRONG 850MB JET (45-55KT) OVER THE WESTERN PANHANDLE...SOUTHEAST AL/SOUTHWEST GA DURING THE SECOND HALF OF THE NIGHT/SUNDAY MORNING. THIS JET WILL ACT TO ENHANCE THE THETA-E RIDGE. STRONG POSITIVE THETA-E ADVECTION IS EXPECTED TO THE NORTH OF THE SURFACE BOUNDARY THROUGH THE FIRST HALF OF SUNDAY...THIS COMBINED WITH THE SYNOPTIC FORCING DESCRIBED ABOVE SHOULD RESULT IN AN AREA OF WIDESPREAD SHOWERS/STORMS FROM KMOB TO PORTIONS OF SE AL AND AREAS GENERALLY NORTH AND WEST OF A LINE FROM KDHN TO KABY. THERE WILL BE THE POTENTIAL WITH THIS SETUP FOR SOME LOCALLY VERY HEAVY RAINFALL...WITH BACKBUILDING AND TRAINING CELLS. IN ADDITION TO HEAVY RAINFALL THREAT...40+ KNOTS OF 0-6KM BULK SHEAR SHOULD BE SUFFICIENT TO SUPPORT A FEW ORGANIZED CELLS. THESE ORGANIZED CELLS COMBINED WITH STEEPENING MID-LEVEL LAPSE RATES AS A RESULT OF THE APPROACHING SHORTWAVE MAY RESULT IN A FEW STRONGER STORMS INTO THE EARLY AFTERNOON. NOT EXPECTING A WIDESPREAD SEVERE WX OUTBREAK...BUT JUST THE POTENTIAL FOR A FEW LOCALIZED DAMAGING WIND GUSTS OR MARGINALLY SEVERE HAIL. EASTWARD MOTION OF THE TROUGH SHOULD HELP TO FINALLY BEGIN PUSHING THE SURFACE BOUNDARY EASTWARD DURING THE AFTERNOON AND EVENING. LARGE SCALE FORCING WILL BE EXITING TO THE NORTHEAST BY THE MIDDLE TO LATER AFTERNOON HOURS RESULTING IN A REDUCTION OF AREAL COVERAGE AND RAINFALL INTENSITY. HOWEVER STILL EXPECT A BAND OF SHOWERS/STORMS TO REACH THE SOUTHEASTERN HALF OF THE REGION DURING THE AFTERNOON/EARLY EVENING SUNDAY. GOING WITH SOME RATHER HIGH POPS FOR THE NORTHWEST HALF OF THE REGION TONIGHT INTO THE FIRST HALF OF SUNDAY WITH WIDESPREAD 70-90%. DYNAMICS LOOK TO REMAIN OVER THESE AREAS FOR MUCH OF THE NIGHT AND WILL ONLY BE GOING WITH SLIGHT CHANCE TO CHANCE POPS FROM KAAF TO KTLH AND KVLD SOUTH AND EAST. FOR THESE AREAS WHERE RAINFALL WILL BE LESS WIDESPREAD...EXPECTING TO ONCE AGAIN SEE AREAS OF DENSE FOG DEVELOP. THIS FOG WILL LIKELY LINGER THROUGH A GOOD PORTION OF THE MORNING AND WILL BE HIGHLIGHTED IN THE AFTERNOON TAF PACKAGE. WILL SHIFT THE HIGHEST POPS EASTWARD FOR THE AFTERNOON HOURS. MOST WIDESPREAD ACTIVITY DURING THE AFTERNOON WILL BE ACROSS SOUTHWEST/SOUTH-CENTRAL GEORGIA...CLOSEST TO THE DEPARTING UPPER DYNAMICS. HIGH PRESSURE BUILDS OVERHEAD FOR SUNDAY NIGHT AS LINGERING SHOWERS DEPART TO THE EAST AND SOUTHEAST DURING THE EVENING HOURS. BACK TO MORE SEASONABLE TEMPERATURES FOR MONDAY WITH FAIR WX FOR ALL. BIG CHANGES THEN COMING FOR THE MIDDLE OF THE WEEK...WILL BE WATCHING A STRONG COLD FRONT APPROACH FROM THE NORTHWEST DURING MONDAY NIGHT. THIS FRONT SHOULD PASS THROUGH THE FORECAST AREA EARLY TUESDAY WITH A MUCH COLDER AIRMASS TO FOLLOW. THIS AIRMASS WILL HAVE THE POTENTIAL TO BE THE COLDEST AIR THAT MANY OF US HAVE SEEN FOR THE SEASON THUSFAR. && .LONG TERM...TUE THROUGH SAT. ZONAL FLOW AT THE BEGINNING OF THE PERIOD TRANSITIONS TO A SHARP TROUGH OVER THE EASTERN U.S. FOR MIDWEEK WITH NEARLY ZONAL FLOW RETURNING BY LATE THURSDAY. A FEW NOTABLE CHANGES WILL BE MADE TO THE EXTENDED GRIDS. FIRST...WILL REMOVE THE SLIGHT POP FOR TUESDAY AS WE FEEL THE FRONT WILL NOT HAVE ENOUGH MOISTURE TO WORK WITH TO PRODUCE ANY APPRECIABLE RAIN. SECOND...BOTH THE GFS AND ECMWF 1000MB-500MB THICKNESS VALUES HAVE INCREASED ACROSS OUR REGION OVER PREVIOUS RUNS AND MEX MIN TEMPS HAVE BACKED OFF FROM THE UPPER TEENS TO THE LOWER TO UPPER 20S FOR THURSDAY MORNING. WILL BUMP TEMPS UP A FEW DEGREES BUT NOT AS MUCH AS GUIDANCE SUGGESTS (I.E. FROM 18 DEGREES TO 27 DEGREES AT TLH) TO AVOID THE POSSIBILITY OF FLIP-FLOPPING. OTHERWISE... AFTER THE BRIEF PERIOD OF COLD TEMPS...WE WILL SEE A GRADUAL WARMING TREND WITH TEMPS RETURNING TO NEAR CLIMO AS WE HEAD INTO THE NEXT WEEKEND. && .MARINE... FLOW WILL CONTINUE FROM A SOUTHERLY DIRECTION WITH A NEARLY STATIONARY FRONTAL BOUNDARY LYING JUST TO THE NORTH OF THE FORECAST WATERS. FLOW IS EXPECTED TO REACH CAUTIONARY LEVELS TONIGHT AND MAY BRIEFLY APPROACH ADVISORY LEVELS LATE. COLD FRONT WILL SLOWLY PUSH EAST ACROSS THE WATERS ON SUNDAY PASSING SOUTH AND EAST OF THE WATERS SUNDAY NIGHT. HIGH PRESSURE THEN BUILDS OVERHEAD FOR MONDAY AND MONDAY EVENING. STRONG COLD FRONT WILL ARRIVE FROM THE NORTHWEST LATE MONDAY NIGHT OR EARLY TUESDAY. WINDS AND SEAS BEHIND THIS FRONT SHOULD EASILY REACH ADVISORY LEVELS AND MAY APPROACH GALE FORCE FOR A TIME...ESPECIALLY IN GUSTS. WINDS WILL DECREASE LATER IN THE WEEK AS HIGH PRESSURE BUILDS TO THE NORTH. && .AVIATION... MOSTLY MVFR CIGS ARE EXPECTED THIS AFTERNOON...EXCEPT IN SHRA AND ISOLATED TSRA WHERE CIGS/VIS WILL TEMPORARILY DROP TO IFR. THE BEST CHANCE FOR RAIN WILL BE AT KDHN...KABY...AND KPFN...BUT KTLH WILL BE NEAR THE EASTERN EDGE OF THIS ACTIVITY. SCATTERED SHRA AND ISOLATED TSRA WILL CONTINUE TONIGHT AND SUNDAY MORNING AT THE SAME TERMINALS. WIDESPREAD FOG AND LOW CIGS WILL DEVELOP AGAIN AFTER SUNSET...AND CONTINUE THROUGH LATE SUNDAY MORNING. && .FIRE WEATHER... RH VALUES ARE EXPECTED TO REMAIN WELL ABOVE CRITICAL LEVELS THROUGH SUNDAY NIGHT. A COLD FRONT WILL SLIDE EAST ACROSS THE AREA SUNDAY AND SUNDAY NIGHT. ENOUGH DRY AIR MAY FILTER INTO THE REGION BEHIND THIS FRONT TO RESULT IN A FEW HOURS OF NEAR CRITICAL RH VALUES OVER PORTIONS OF NORTH FLORIDA. AT THIS TIME...CONFIDENCE IS A BIT LOW...BUT THE SITUATION WILL BE MONITORED CLOSELY IN CASE A WATCH OR WARNING BECOMES NECESSARY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 61 74 46 67 42 / 50 80 20 10 10 PANAMA CITY 63 72 48 65 46 / 70 70 10 10 10 DOTHAN 57 63 41 65 40 / 80 90 10 10 10 ALBANY 58 67 42 65 39 / 70 90 20 10 10 VALDOSTA 60 74 47 67 42 / 40 80 30 10 10 CROSS CITY 61 77 53 71 47 / 20 50 40 10 10 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ AVIATION/FIRE WX...FOURNIER PUBLIC/MARINE...MROCZKA LONG TERM...BARRY fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 629 AM EST SAT DEC 29 2007 .SYNOPSIS... A COLD FRONT WILL APPROACH THE AREA TODAY AND MOVE THROUGH TONIGHT. THE FRONT WILL BECOME STATIONARY NEAR THE COAST SUNDAY AS A LOW DEVELOPS ON IT. THIS WILL SPREAD RAIN OVER THE AREA SUNDAY AS WELL. THE LOW AND FRONT WILL MOVE AWAY MONDAY AS HIGH PRESSURE BUILDS IN. && .NEAR TERM /UNTIL NOON TODAY/... AGREE WITH NAM/RUC MODELS CONTINUING TO PUMP MOISTURE OVER THE AREA AHEAD OF AN APPROACHING COLD FRONT. THERE WILL BE A CHANCE OF SHOWERS DURING THE PERIOD. WARM TEMPERATURES IN THE MID TO UPPER 60S EXPECTED. && .SHORT TERM /NOON TODAY THROUGH MONDAY/... UPPER FLOW SOUTHWEST. SO NOT MUCH PUSH TO COLD FRONT. FRONT STILL WEST OF AREA THIS AFTERNOON WITH LOW LEVEL SOUTHWEST WIND FLOW CONTINUING TO BRING IN MOISTURE. AIRMASS BECOMES MODERATELY UNSTABLE THIS AFTERNOON. NAM LIS -4/-5 WITH CAPES 500-600. PW VALUES INCREASE FROM 1.30 INCH TO 1.60 INCH THIS AFTERNOON. SO THERE MAY BE A FEW THUNDERSTORMS AROUND BUT NOTHING SEVERE. SPC HAS CAE CWA OUTLOOKED FOR GENERAL THUNDERSTORMS. WILL SAY CHANCE OF SHOWERS WITH A SLIGHT CHANCE OF THUNDERSTORMS. TEMPERATURES ALREADY WARM IN THE MID 60S. SO WILL GO WITH HIGHS NEAR 70 CAE AND CENTRAL MIDLANDS. COOLER TO THE NORTH THOUGH. COLD FRONT SLIDES THROUGH TONIGHT. SINCE UPPER FLOW IS STILL SOUTHWEST...IT WILL BE A SLOW MOVER AND WILL EVENTUALLY STALL OUT NEAR THE COAST EARLY SUNDAY MORNING. AGREE WITH MODELS THAT LOW PRESSURE WILL DEVELOP ON THE FRONT NEAR THE COAST. AS IT DOES...A GOOD WEDGE DEVELOPS RIGHT OVER THE MIDLANDS. WITH NAM SHOWING 850/925 MB WINDS SOUTHWEST AT 40 KT SUNDAY OVER WEDGE AND GOOD ISENTROPIC LIFT... WILL GO CATEGORICAL CHANCE FOR RAIN SUNDAY. HIGH TEMPERATURES IN THE MID 50S BUT WILL HAVE FALLING TEMPERATURES SUNDAY AFTERNOON INTO THE UPPER 40S AND LOWER 50S. STRONG SHORT WAVE MOVES THROUGH SUNDAY NIGHT ENDING THE RAIN AND HIGH PRESSURE BUILDS IN MONDAY. DRIER AND COOLER MONDAY. LOWS MID-UPPER 30S. HIGHS UPPER 50S TO LOWER 60S. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AGREE WITH GFS SHOWING BROAD UPPER TROUGH SHIFTING EASTWARD AND BRINGING COLDER TEMPERATURES TO THE AREA. UPPER FLOW FINALLY STRAIGHTENS OUT THURSDAY AND FRIDAY. CLIPPER SYSTEM NEAR GREAT LAKES MOVES EASTWARD TUESDAY BRINGING COLDER AIR TO AREA. THEN COLD HIGH PRESSURE WILL COVER AREA WEDNESDAY THROUGH FRIDAY. HIGHS MAINLY UPPER 40S TO LOWER 50S TUESDAY THROUGH THURSDAY BUT INCREASE A BIT INTO THE LOWER TO MID 50S BY FRIDAY. OVERNIGHT LOWS DROP INTO THE 20S. && .AVIATION /12Z SATURDAY THROUGH THURSDAY/... WEAK COLD FRONT APPROACHING WESTERN CAROLINAS THIS MORNING AND WILL MOVE CLOSE TO THE COAST BY THIS EVENING. EXPECT SOME IFR CIGS 12Z-14Z THIS MORNING BECOMING MVFR/VFR IN MOST LOCATIONS FOR MUCH OF THE TAF PERIOD. SCATTERED SHOWERS LATER TODAY WITH AN ISOLATED THUNDERSTORM POSSIBLE LATE THIS AFTERNOON INTO EARLY THIS EVENING. A FEW SHOWERS POSSIBLE LATE TONIGHT BEYOND 04Z SUNDAY UNTIL END OF TAF PERIOD. PATCHY FOG ESPECIALLY AFTER 06Z SUNDAY MAY RECUSE VSBYS TO AROUND 4-5 MILES IN A FEW LOCATIONS UNTIL THE END OF THE TAF PERIOD. MVFR TO IFR CEILINGS AND VSBYS POSSIBLE WITH PRECIPITATION SUNDAY AND SUNDAY NIGHT AS ANOTHER DISTURBANCE AND LOW PRESSURE SYSTEM MOVE THROUGH. OTHERWISE NO SIGNIFICANT IMPACTS TO AVIATION EXPECTED. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1152 AM CST SAT DEC 29 2007 .DISCUSSION... ISSUED 1045 AM CST SAT DEC 29 2007 MINOR UPDATES TO FORECAST TODAY WITH TWEAKING DECREASING CLOUDS FROM THE SW AND COOLED HIGHS A DEGREE OR TWO OVER 1 TO 3 INCH SNOW COVER NW OF THE IL RIVER. LOW CLOUDS TO GIVE WAY TO PARTLY SUNNY SKIES THOUGH NE AREAS WILL LIKELY STAY IN THE CLOUDS MOST OF THE DAY. HIGHS IN THE MID TO UPPER 30S EXCEPT LOWER 30S NW OF THE IL RIVER. GENTLE SW WINDS 5 TO 10 MPH. LATE MORNING SURFACE ANALYSIS SHOWS 1024 MB HIGH PRESSURE OVER AR AND RIDGING UP INTO IL. ALOFT IL REMAINS IN A SW UPPER LEVEL FLOW IWTH UPPER LEVEL RIDGE OFF THE WEST AND EAST COAST AND BROAD UPPER LEVEL TROF OVER THE GREAT PLAINS. TEMPS OVER CENTRAL IL WERE IN THE UPPER 20S AND LOWER 30S WITH OLNEY AND LAWRENCEVILLE UP TO 34F. LOW CLOUDS OF 1500 TO 2500 FT COVERED MUCH OF IL THIS MORNING THOUGH CLEARING SKIES IN WEST CENTRAL IL WORKING SLOWLY NE TOWARD MACOMB AND JACKSONVILLE. RUC...WRF AND SHEF MODELS DRIFT HIGH PRESSURE EAST OF THE OHIO VALLEY THIS EVENING WITH WSW WIND BECOMING SOUTH UNDER 10 MPH. RUC 900 TO 950 MB RH CONTINUES TO DO WELL WITH THE LOW CLOUD COVER AND USED THIS TO TIME DECREASE LOW CLOUDS FROM THE SW. BACK EDGE OF LOW CLOUDS NEAR MACOMB AND JACKSONVILLE TO MOVE NE TO I-74 AROUND 21Z/3 PM AND PASS FAR NE AREAS LATE AFTERNOON AS SUN SETS. CURULE SHOWS SCATTERED LOW CLOUDS COULD REDEVELOP OVER NW PARTS THIS AFTERNOON. COOLED HIGHS A DEGREE OR TWO INTO THE LOWER 30S OVER 1 TO 3 INCH SNOW COVER NW OF THE IL RIVE. REST OF CENTRAL AND IL HAS LITTLE IF ANY SNOW AND MILDER HIGHS IN THE MID TO UPPER 30S. HUETTL && .AVIATION... ISSUED 1150 AM CST SAT DEC 29 2007 MVFR CEILINGS AROUND 1500 FT WILL SCATTERED OUT AT SPI BETWEEN 18-19Z...DEC AND PIA BETWEEN 19-21Z AND BMI AND CMI BETWEEN 21Z-23Z. ONCE LOW CLOUDS LIFT NE OF CENTRAL IL DURING THE AFTERNOON... VFR CONDITIONS SHOULD PREVAIL ACROSS THE CENTRAL IL TAF SITES THROUGH 18Z/SUN. 1024 MB HIGH PRESSURE OVER AR AND RIDGING UP INTO EASTERN IL WILL MOVE EAST INTO THE OHIO VALLEY THIS EVENING...AND TOWARD THE NEW ENGLAND COAST BY 18Z/SUN. MEANWHILE AN UPPER LEVEL TROF OVER THE PLAINS WILL WEAKEN/DAMPEN OUT AS IT MOVES TOWARD IL SUNDAY. SW WINDS NEAR 8 KTS THIS AFTERNOON BECOME SOUTH AROUND 5 KTS TONIGHT AND BACK AROUND 8 KTS SUN MORNING. SCATTERED MID/HIGH CLOUDS TO AFFECT CENTRAL IL TONIGHT AND SUNDAY MORNING WITH BROKEN CEILINGS MAINLY STAYING SE OF TAF SITES OVER SE IL OVERNIGHT AND SUNDAY MORNING. LIGHT FOG COULD DEVELOP OVERNIGHT OVER 1 TO 3 INCH SNOW PACK NW OF THE IL RIVER WITH PIA ON EDGE OF THIS. HUETTL && .PREV DISCUSSION... ISSUED 237 AM CST SAT DEC 29 2007 MAIN CHALLENGE WITH THIS FORECAST PACKAGE WILL BE TIMING OF CLEARING TREND TODAY. 07Z SURFACE ANALYSIS SHOWS LOW PRESSURE OVER LAKE HURON...WITH COLD FRONT TRAILING SOUTHWARD INTO THE APPALACHIANS. FURTHER WEST...WEAK AREA OF HIGH PRESSURE IS CENTERED OVER THE SOUTHERN PLAINS. LOW CLOUDINESS STILL BLANKETS ILLINOIS...HOWEVER LATEST SATELLITE IMAGERY SHOWS CLEARING SLOWLY PROGRESSING EASTWARD ACROSS MISSOURI. SHORT TERM...TODAY THROUGH MONDAY BIG QUESTION TODAY WILL BE HOW FAST CLEARING WILL OCCUR. MODEL RH FIELDS DO NOT APPEAR TO BE TOO HELPFUL...ALTHOUGH THE RUC 900-950MB LAYER RH SEEMS TO BE HANDLING THE CURRENT TRENDS RELATIVELY WELL. WILL USE THIS PARTICULAR FIELD IN CONJUNCTION WITH SATELLITE LOOPS TO TIME CLEARING ACROSS THE AREA. 08Z SATELLITE IMAGERY SHOWS BACK EDGE OF LOW CLOUD COVER HAS NOW ADVANCED TO NEAR KIRKSVILLE MISSOURI AND IS ONLY SLOWLY PROGRESSING EASTWARD. BASED ON SATELLITE TIMING TOOL...CLOUDS SHOULD BREAK UP ACROSS THE FAR SOUTHWEST KILX CWA BETWEEN 14Z AND 15Z...WITH CLEARING TREND REACHING THE I-55 CORRIDOR BY AROUND MIDDAY. LOCATIONS FURTHER EAST WILL REMAIN OVERCAST UNTIL AFTERNOON. THERMAL ADVECTION WILL BE RELATIVELY NEUTRAL TODAY...HOWEVER GIVEN THE SLOW NATURE OF THE CLEARING...HAVE OPTED TO UNDERCUT NUMERIC GUIDANCE BY A FEW DEGREES. HIGH TEMPS WILL TOP OUT IN THE MIDDLE TO UPPER 30S...WITH THE COOLEST READINGS ACROSS THE E/NE CWA. AFTER A COOL NIGHT TONIGHT...SLIGHTLY WARMER WEATHER WILL BE ON TAP FOR SUNDAY AS S/SW FLOW DEVELOPS ON BACK SIDE OF DEPARTING HIGH PRESSURE. HIGH TEMPS WILL RISE INTO THE 40S IN MOST LOCATIONS. NEXT POTENTIAL WEATHER MAKER WILL APPROACH THE REGION SUNDAY NIGHT INTO MONDAY. MODELS CONTINUE TO KEEP BULK OF THIS SYSTEM TO THE NORTH OF CENTRAL ILLINOIS...AS LOW PRESSURE TRACKS FROM THE NORTHERN PLAINS INTO THE GREAT LAKES. TRAILING COLD FRONT WILL PUSH INTO CENTRAL ILLINOIS DURING THE DAY MONDAY...ACCOMPANIED BY SCATTERED LIGHT PRECIP. NAM-WRF DOES NOT INDICATE MUCH IN THE WAY OF QPF AT ALL...WHILE GFS IS A BIT MORE AGGRESSIVE. WILL FOLLOW THE GFS AT THIS POINT AND INTRODUCE 40 POPS ACROSS THE BOARD. WITH HIGH TEMPS EXPECTED TO BE WELL INTO THE 30S ACROSS MUCH OF THE CWA...WILL GO WITH RAIN SHOWERS ACROSS THE SE...AND RAIN OR SNOW SHOWERS CENTRAL. REGARDLESS OF PRECIP TYPE...AMOUNTS WILL BE QUITE LIGHT. LONG TERM...TUESDAY THROUGH FRIDAY ONCE MONDAY SYSTEM EXITS THE REGION...A SECONDARY WAVE WILL DIVE SOUTHWARD OUT OF CANADA AND CARVE OUT A DEEP TROUGH ACROSS THE EASTERN CONUS EARLY NEXT WEEK. SHARPENING CYCLONIC FLOW COMBINED WITH AMPLE LOW-LEVEL RH...WILL LEAD TO SCATTERED SNOW FLURRIES MONDAY NIGHT AND TUESDAY. BLUSTERY N/NW WINDS WILL TRANSPORT MUCH COLDER AIR INTO THE REGION...WITH THERMAL PROFILES SUGGESTING HIGHS ONLY IN THE 20S TUESDAY AND WEDNESDAY...WITH OVERNIGHT LOWS DIPPING INTO THE SINGLE DIGITS AND TEENS. AFTER THAT...PROGRESSIVE PATTERN CONTINUES...AS TROUGH FLATTENS AND FLOW BECOMES ZONAL BY THE END OF THE WEEK. END RESULT WILL BE A RAPID WARMING TREND FOR THURSDAY AND FRIDAY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 551 AM CST SAT DEC 29 2007 .DISCUSSION... ISSUED 237 AM CST SAT DEC 29 2007 MAIN CHALLENGE WITH THIS FORECAST PACKAGE WILL BE TIMING OF CLEARING TREND TODAY. 07Z SURFACE ANALYSIS SHOWS LOW PRESSURE OVER LAKE HURON...WITH COLD FRONT TRAILING SOUTHWARD INTO THE APPALACHIANS. FURTHER WEST...WEAK AREA OF HIGH PRESSURE IS CENTERED OVER THE SOUTHERN PLAINS. LOW CLOUDINESS STILL BLANKETS ILLINOIS...HOWEVER LATEST SATELLITE IMAGERY SHOWS CLEARING SLOWLY PROGRESSING EASTWARD ACROSS MISSOURI. SHORT TERM...TODAY THROUGH MONDAY BIG QUESTION TODAY WILL BE HOW FAST CLEARING WILL OCCUR. MODEL RH FIELDS DO NOT APPEAR TO BE TOO HELPFUL...ALTHOUGH THE RUC 900-950MB LAYER RH SEEMS TO BE HANDLING THE CURRENT TRENDS RELATIVELY WELL. WILL USE THIS PARTICULAR FIELD IN CONJUNCTION WITH SATELLITE LOOPS TO TIME CLEARING ACROSS THE AREA. 08Z SATELLITE IMAGERY SHOWS BACK EDGE OF LOW CLOUD COVER HAS NOW ADVANCED TO NEAR KIRKSVILLE MISSOURI AND IS ONLY SLOWLY PROGRESSING EASTWARD. BASED ON SATELLITE TIMING TOOL...CLOUDS SHOULD BREAK UP ACROSS THE FAR SOUTHWEST KILX CWA BETWEEN 14Z AND 15Z...WITH CLEARING TREND REACHING THE I-55 CORRIDOR BY AROUND MIDDAY. LOCATIONS FURTHER EAST WILL REMAIN OVERCAST UNTIL AFTERNOON. THERMAL ADVECTION WILL BE RELATIVELY NEUTRAL TODAY...HOWEVER GIVEN THE SLOW NATURE OF THE CLEARING...HAVE OPTED TO UNDERCUT NUMERIC GUIDANCE BY A FEW DEGREES. HIGH TEMPS WILL TOP OUT IN THE MIDDLE TO UPPER 30S...WITH THE COOLEST READINGS ACROSS THE E/NE CWA. AFTER A COOL NIGHT TONIGHT...SLIGHTLY WARMER WEATHER WILL BE ON TAP FOR SUNDAY AS S/SW FLOW DEVELOPS ON BACK SIDE OF DEPARTING HIGH PRESSURE. HIGH TEMPS WILL RISE INTO THE 40S IN MOST LOCATIONS. NEXT POTENTIAL WEATHER MAKER WILL APPROACH THE REGION SUNDAY NIGHT INTO MONDAY. MODELS CONTINUE TO KEEP BULK OF THIS SYSTEM TO THE NORTH OF CENTRAL ILLINOIS...AS LOW PRESSURE TRACKS FROM THE NORTHERN PLAINS INTO THE GREAT LAKES. TRAILING COLD FRONT WILL PUSH INTO CENTRAL ILLINOIS DURING THE DAY MONDAY...ACCOMPANIED BY SCATTERED LIGHT PRECIP. NAM-WRF DOES NOT INDICATE MUCH IN THE WAY OF QPF AT ALL...WHILE GFS IS A BIT MORE AGGRESSIVE. WILL FOLLOW THE GFS AT THIS POINT AND INTRODUCE 40 POPS ACROSS THE BOARD. WITH HIGH TEMPS EXPECTED TO BE WELL INTO THE 30S ACROSS MUCH OF THE CWA...WILL GO WITH RAIN SHOWERS ACROSS THE SE...AND RAIN OR SNOW SHOWERS CENTRAL. REGARDLESS OF PRECIP TYPE...AMOUNTS WILL BE QUITE LIGHT. LONG TERM...TUESDAY THROUGH FRIDAY ONCE MONDAY SYSTEM EXITS THE REGION...A SECONDARY WAVE WILL DIVE SOUTHWARD OUT OF CANADA AND CARVE OUT A DEEP TROUGH ACROSS THE EASTERN CONUS EARLY NEXT WEEK. SHARPENING CYCLONIC FLOW COMBINED WITH AMPLE LOW-LEVEL RH...WILL LEAD TO SCATTERED SNOW FLURRIES MONDAY NIGHT AND TUESDAY. BLUSTERY N/NW WINDS WILL TRANSPORT MUCH COLDER AIR INTO THE REGION...WITH THERMAL PROFILES SUGGESTING HIGHS ONLY IN THE 20S TUESDAY AND WEDNESDAY...WITH OVERNIGHT LOWS DIPPING INTO THE SINGLE DIGITS AND TEENS. AFTER THAT...PROGRESSIVE PATTERN CONTINUES...AS TROUGH FLATTENS AND FLOW BECOMES ZONAL BY THE END OF THE WEEK. END RESULT WILL BE A RAPID WARMING TREND FOR THURSDAY AND FRIDAY. BARNES && .AVIATION... ISSUED 551 AM CST SAT DEC 29 2007 GENERALLY QUIET AVIATION CONDITIONS EXPECTED THROUGH THE 12Z TAF PERIOD...AT LEAST ONCE THE MVFR CEILINGS DEPART. HIGH PRESSURE WILL BUILD ACROSS THE REGION TODAY FROM THE WEST...WITH WINDS AOB 10 KTS GRADUALLY SHIFTING FROM WEST TO SOUTH. MVFR CEILINGS WILL CLEAR OUT FROM SOUTHWEST TO NORTHEAST ACROSS THE CENTRAL ILLINOIS TERMINALS FROM AROUND MIDDAY INTO MID AFTERNOON. ONCE THE LOWER CEILINGS MOVE EAST OF THE REGION...VFR CONDITIONS WILL PREVAIL. BAK && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1035 AM MST SUN DEC 30 2007 .AVIATION... VFR CONDITIONS ARE EXPECTED ACROSS THE AREA THROUGH 18Z MONDAY. A WEAK SHORT WAVE TROUGH WILL BRING INCREASING CLOUDS TO THE AREA LATE THIS AFTERNOON AND INTO THE EVENING...BUT CIGS SHOULD ONLY LOWER TO AROUND 6 KFT. AS TROUGH PASSES...STRONG COLD FRONT WILL SWEEP ACROSS THE AREA BRINGING STRONG NORTHWESTERLY WINDS AS FRONT PASSES WITH GUSTS AROUND 30KTS BEFORE WINDS RELAX SOME OVERNIGHT. WINDS SHOULD ONCE AGAIN PICK UP QUICKLY OUT OF THE NORTHWEST AFTER SUNRISE. && .DISCUSSION...FORECAST CONCERNS ARE TEMPERATURES THROUGH THE NEXT SEVERAL DAYS AND WINDS TONIGHT THROUGH SUNDAY AND THE IMPACT EXISTING SNOW PACK WILL HAVE ON BOTH OF THEM. .SHORT TERM (TODAY-TUESDAY NIGHT)... WEST TO NORTHWEST WINDS AND 850 TEMPERATURES WARMING SOME 4-9F (COOLEST ACROSS THE NORTHWEST AND WEST WHERE DEEPEST SNOW PACK EXISTS) WILL ALLOW FOR A BIT MORE MELTING ACROSS THE AREA AS TEMPERATURES WARM INTO THE LOW 30S WEST AND NORTH WITH NEAR 40 AND SOME LOWER 40S ACROSS THE AREAS WHERE LITTLE OR NO SNOW PACK EXISTS. THIS WARMING TREND WILL BE SHORT LIVED AS A 140+ KT 250 JET AND PACIFIC COLD FRONT MOVE INTO THE AREA DURING THE OVERNIGHT HOURS. LOW TEMPS WILL BE COLDEST ACROSS THE WEST...LESS COLD ACROSS THE EAST. NORTHWEST WINDS IN THE 15-25/20-30 MPH RANGE WILL ALSO BE COMMON. AS FAR AS PRECIPITATION CHANCES...GFS STILL LOOKS OVERDONE WITH OVERALL MOISTURE PROFILES. NAM/NGM/RUC QUITE A BIT DRIER. IF THE GFS WERE TO VERIFY SOME LOW POPS MAY BE NEEDED FOR SOME LIGHT SHOWERS OR SILENT POPS FOR VIRGA AS THEY (NGM/NAM/GFS) SHOW SOME GOOD 700 FRONTOGENESIS WITHIN THE HIGHER 850-500 MOISTURE THAT THE GFS GENERATES ACROSS THE NORTHERN HALF OF THE AREA. WILL BRIEF DAY SHIFT TO THIS BUT I DONT SEE ANYTHING HAPPENING RIGHT NOW. FOR MONDAY 850 TEMPERATURES DROP ABOUT 15F ACROSS THE AREA WHICH ALONE WITH ONLY SUPPORT 20-25 ACROSS THE DEEPER SNOW PACK AREAS OF FAR EASTERN COLORADO AND SOUTHWEST NEBRASKA WITH 30 OR SO ELSEWHERE. 21Z SREF TEMPS ALSO SIMILAR BUT THE MOS GUIDANCE SEEMS OUT TO LUNCH WHICH GIVEN THE SNOW PACK MAKES SENSE. ADD TO THAT THE FACT THAT THE WIND WILL BE BLOWING FROM THE DEEPER SNOW PACK SOUTHEAST ACROSS THE REST OF THE AREA...POSSIBLY FURTHER IMPACTING THE TEMPERATURE FORECAST. SPEAKING OF WINDS...ANOTHER TOUGH FORECAST. LOCAL WIND GUST PROGRAM BASED ON THE NAM WOULD SUGGEST POSSIBLE WARNING CRITERIA GUSTS AS 50+ KT 800MB WINDS COVER THE AREA. SNOW PACK AREAS MAY CREATE A SHALLOW INVERSION WHICH WOULD PREVENT FULL GUST POTENTIAL TO REACH THE SURFACE. FOR NOW HAVE FOLLOWED THE SREF FOR WIND DIRECTION AND THE RUC/RUC13/MOS GUIDANCE NUMBERS FOR SUSTAINED WINDS. MIN TEMPS MONDAY NIGHT WILL BE IN THE SINGLE DIGITS BOTH ABOVE AND BELOW ZERO ACROSS FAR EASTERN COLORADO WITH SINGLE DIGITS ABOVE TO AROUND 10-15 ABOVE ZERO ACROSS THE FAR EASTERN PARTS OF THE AREA. NORTHWEST WINDS OF 15 TO 20 MPH WILL ALSO BE COMMON AS THE GRADIENT REMAINS TIGHT AND ATMOSPHERE MIXED. FOR TUESDAY AND TUESDAY NIGHT UPPER RIDGE AXIS PUSHES TOWARD THE FRONT RANGE BY THE END OF THE PERIOD. 850 TEMPERATURES HOWEVER SHOW LITTLE CHANGE FROM MONDAYS READINGS. THIS WOULD AGAIN SUPPORT 20S IN THE WEST AND NORTH WITH NEAR 30/LOW 30S ELSEWHERE. SHOULD SEE LOTS OF SUN WITH ONLY SOME CIRRUS POSSIBLE...NOT ENOUGH TO IMPACT THE TEMPERATURE FORECAST. MIN TEMPS WILL AGAIN BE IN THE SINGLE DIGITS WITH POSSIBLE BELOW ZERO READINGS ACROSS YUMA COUNTY COLORADO AND KIT CARSON COLORADO (SOUTHWEST PORTION OF CHEYENNE COUNTY). .LONG TERM (WEDNESDAY-SATURDAY)... WEDNESDAY...LIKE THE GFS IDEA AT 850 MB AS IT SEEMS TO HAVE A GOOD IDEA WHERE SNOW PACK IS AND APPROPRIATELY HAS THE COOLER 850 TEMPERATURES IN THAT AREA. WITH THE GFS WARMING 850 TEMPS ABOUT 10F ACROSS THE AREA ADDED THAT ON TO TUESDAYS FORECAST HIGH GRID. WILL GO FOR 35-40 ACROSS THE NORTH AND WEST WITH 40-45 ELSEWHERE. THURSDAY...TEMPERATURES WILL CONTINUE TO WARM WITH THE QUESTION BEING JUST HOW MUCH. GFS SHOWS ABOUT 10F ON AVERAGE WHILE THE ACTUAL 850 TEMPS FROM THE ECMWF ARE SOME 2-6C WARMER ON AVERAGE. IMPACTS OF ANY EXISTING SNOW PACK SHOULD BE MINIMAL AT THIS POINT BUT WONT TOTALLY EXCLUDE IT AT THIS POINT. HAVE GONE WITH READINGS GENERALLY IN THE 45-53 RANGE...COOLEST ACROSS THE NORTH AND WEST. FRIDAY AND SATURDAY...NO CHANGES MADE AT THIS TIME. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JRM/DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MST SUN DEC 30 2007 .DISCUSSION...FORECAST CONCERNS ARE TEMPERATURES THROUGH THE NEXT SEVERAL DAYS AND WINDS TONIGHT THROUGH SUNDAY AND THE IMPACT EXISTING SNOW PACK WILL HAVE ON BOTH OF THEM. .SHORT TERM (TODAY-TUESDAY NIGHT)... WEST TO NORTHWEST WINDS AND 850 TEMPERATURES WARMING SOME 4-9F (COOLEST ACROSS THE NORTHWEST AND WEST WHERE DEEPEST SNOW PACK EXISTS) WILL ALLOW FOR A BIT MORE MELTING ACROSS THE AREA AS TEMPERATURES WARM INTO THE LOW 30S WEST AND NORTH WITH NEAR 40 AND SOME LOWER 40S ACROSS THE AREAS WHERE LITTLE OR NO SNOW PACK EXISTS. THIS WARMING TREND WILL BE SHORT LIVED AS A 140+ KT 250 JET AND PACIFIC COLD FRONT MOVE INTO THE AREA DURING THE OVERNIGHT HOURS. LOW TEMPS WILL BE COLDEST ACROSS THE WEST...LESS COLD ACROSS THE EAST. NORTHWEST WINDS IN THE 15-25/20-30 MPH RANGE WILL ALSO BE COMMON. AS FAR AS PRECIPITATION CHANCES...GFS STILL LOOKS OVERDONE WITH OVERALL MOISTURE PROFILES. NAM/NGM/RUC QUITE A BIT DRIER. IF THE GFS WERE TO VERIFY SOME LOW POPS MAY BE NEEDED FOR SOME LIGHT SHOWERS OR SILENT POPS FOR VIRGA AS THEY (NGM/NAM/GFS) SHOW SOME GOOD 700 FRONTOGENESIS WITHIN THE HIGHER 850-500 MOISTURE THAT THE GFS GENERATES ACROSS THE NORTHERN HALF OF THE AREA. WILL BRIEF DAY SHIFT TO THIS BUT I DONT SEE ANYTHING HAPPENING RIGHT NOW. FOR MONDAY 850 TEMPERATURES DROP ABOUT 15F ACROSS THE AREA WHICH ALONE WITH ONLY SUPPORT 20-25 ACROSS THE DEEPER SNOW PACK AREAS OF FAR EASTERN COLORADO AND SOUTHWEST NEBRASKA WITH 30 OR SO ELSEWHERE. 21Z SREF TEMPS ALSO SIMILAR BUT THE MOS GUIDANCE SEEMS OUT TO LUNCH WHICH GIVEN THE SNOW PACK MAKES SENSE. ADD TO THAT THE FACT THAT THE WIND WILL BE BLOWING FROM THE DEEPER SNOW PACK SOUTHEAST ACROSS THE REST OF THE AREA...POSSIBLY FURTHER IMPACTING THE TEMPERATURE FORECAST. SPEAKING OF WINDS...ANOTHER TOUGH FORECAST. LOCAL WIND GUST PROGRAM BASED ON THE NAM WOULD SUGGEST POSSIBLE WARNING CRITERIA GUSTS AS 50+ KT 800MB WINDS COVER THE AREA. SNOW PACK AREAS MAY CREATE A SHALLOW INVERSION WHICH WOULD PREVENT FULL GUST POTENTIAL TO REACH THE SURFACE. FOR NOW HAVE FOLLOWED THE SREF FOR WIND DIRECTION AND THE RUC/RUC13/MOS GUIDANCE NUMBERS FOR SUSTAINED WINDS. MIN TEMPS MONDAY NIGHT WILL BE IN THE SINGLE DIGITS BOTH ABOVE AND BELOW ZERO ACROSS FAR EASTERN COLORADO WITH SINGLE DIGITS ABOVE TO AROUND 10-15 ABOVE ZERO ACROSS THE FAR EASTERN PARTS OF THE AREA. NORTHWEST WINDS OF 15 TO 20 MPH WILL ALSO BE COMMON AS THE GRADIENT REMAINS TIGHT AND ATMOSPHERE MIXED. FOR TUESDAY AND TUESDAY NIGHT UPPER RIDGE AXIS PUSHES TOWARD THE FRONT RANGE BY THE END OF THE PERIOD. 850 TEMPERATURES HOWEVER SHOW LITTLE CHANGE FROM MONDAYS READINGS. THIS WOULD AGAIN SUPPORT 20S IN THE WEST AND NORTH WITH NEAR 30/LOW 30S ELSEWHERE. SHOULD SEE LOTS OF SUN WITH ONLY SOME CIRRUS POSSIBLE...NOT ENOUGH TO IMPACT THE TEMPERATURE FORECAST. MIN TEMPS WILL AGAIN BE IN THE SINGLE DIGITS WITH POSSIBLE BELOW ZERO READINGS ACROSS YUMA COUNTY COLORADO AND KIT CARSON COLORADO (SOUTHWEST PORTION OF CHEYENNE COUNTY). .LONG TERM (WEDNESDAY-SATURDAY)... WEDNESDAY...LIKE THE GFS IDEA AT 850 MB AS IT SEEMS TO HAVE A GOOD IDEA WHERE SNOW PACK IS AND APPROPRIATELY HAS THE COOLER 850 TEMPERATURES IN THAT AREA. WITH THE GFS WARMING 850 TEMPS ABOUT 10F ACROSS THE AREA ADDED THAT ON TO TUESDAYS FORECAST HIGH GRID. WILL GO FOR 35-40 ACROSS THE NORTH AND WEST WITH 40-45 ELSEWHERE. THURSDAY...TEMPERATURES WILL CONTINUE TO WARM WITH THE QUESTION BEING JUST HOW MUCH. GFS SHOWS ABOUT 10F ON AVERAGE WHILE THE ACTUAL 850 TEMPS FROM THE ECMWF ARE SOME 2-6C WARMER ON AVERAGE. IMPACTS OF ANY EXISTING SNOW PACK SHOULD BE MINIMAL AT THIS POINT BUT WONT TOTALLY EXCLUDE IT AT THIS POINT. HAVE GONE WITH READINGS GENERALLY IN THE 45-53 RANGE...COOLEST ACROSS THE NORTH AND WEST. FRIDAY AND SATURDAY...NO CHANGES MADE AT THIS TIME. && .AVIATION... THROUGH 12Z MONDAY...CIGS AT BOTH KGLD AND KMCK IN THE 10-15K FT RANGE MAINLY EARLY THIS MORNING AND AGAIN DURING THE AFTERNOON/EARLY EVENING HOURS. WINDS GENERALLY FROM THE WEST/NORTHWEST AT 15 KTS THIS MORNING...SHIFTING TO THE SOUTHWEST BY 21Z. A COLD FRONT WILL MOVE INTO THE AREA BETWEEN 03Z-06Z SHIFTING THE WINDS TO THE NORTHWEST AND INCREASING SPEEDS INTO THE 20KT RANGE WITH HIGHER GUSTS. THESE GUSTY NORTHWEST WINDS WILL CONTINUE FOR THE REMAINDER OF THE TAF PERIOD. VFR CONDITIONS EXPECTED AT BOTH SITES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ DDT/DDT/DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MST SAT DEC 29 2007 .DISCUSSION...FORECAST CONCERNS ARE TEMPERATURES THROUGHOUT THE SHORT AND LONG TERM PERIOD WITH WINDS BECOMING A CONCERN SUNDAY NIGHT AND MONDAY. .SHORT TERM (TODAY-MONDAY NIGHT)... A WEAK UPPER TROUGH AXIS CURRENTLY EXTENDING ALONG THE CONTINENTAL DIVIDE WILL SLOWLY MOVE EAST TODAY WITH FAST NORTHWEST FLOW TO FOLLOW THROUGH SUNDAY. FOR SUNDAY NIGHT INTO MONDAY NIGHT SOME INCREASING UPPER LEVEL ENERGY MOVING THROUGH NORTHERN PLAINS WILL PUSH A COLD FRONT THROUGH THE NORTHWEST 1/3-2/3 OF THE AREA BY MONDAY MORNING...CLEARING THE AREA SHORTLY THEREAFTER. WITH AN INCREASING PRESSURE GRADIENT BEHIND THE FRONT WINDS WILL INCREASE INTO THE WINDY CATEGORY AS WELL SUNDAY NIGHT AND MONDAY WITH A SLIGHT DECREASE MONDAY NIGHT. GFS IS THE BOLDEST WITH REGARD TO MOISTURE WITH THE FRONTAL PASSAGE PRODUCING SOME LIGHT QPF. THE NAM/SREF/CANADIAN AND RUC13 ARE ALL DRY. HAVE KEPT THE FORECAST DRY AT THIS POINT. FOR TEMPERATURES TODAY I USED FRIDAYS OBSERVED TEMPERATURES FROM ASOS AND MESONET SITES THEN ADDED APPROXIMATELY 5F TO ACCOUNT FOR 850 WARMING AND LATEST 2M/MOS GUIDANCE AVERAGES. SIMILARLY...SUNDAYS HIGHS SIMPLY ADDED ANOTHER 10F OR SO TO SATURDAYS AS 850/2M/MOS GUIDANCE NUMBERS CONTINUE TO WARM. SHARPLY COLDER ON MONDAY...ESPECIALLY WEST WHERE 850/2M/MOS NUMBERS FAVOR HIGHS ONLY 20S WHERE LOW/MID 30S EXPECTED ACROSS THE FAR SOUTH AND EAST. CONFIDENCE IS MODERATE IN THE TEMP FORECAST AS RECENT AND PREVIOUS STORMS SNOW PACK MAKES IT ALL THAT MORE DIFFICULT TO PINPOINT BOTH HIGHS AND LOWS. WITH AIRMASS MODIFYING/WARMING AND A SUSTAINED WEST/SOUTHWEST WIND MINS TONIGHT MIGHT BE ON THE LOW SIDE OF THINGS. .LONG TERM (TUESDAY-FRIDAY)... TUESDAY...THE ABOVE MENTIONED PIECE OF UPPER LEVEL ENERGY AND COLD POCKET WILL CONTINUE TO PUSH SOUTHEAST INTO THE OHIO VALLEY BY 00Z WEDNESDAY PREVENTING ANY TYPE OF SUBSTANTIAL WARM UP DESPITE BUILDING UPPER HEIGHTS FROM THE WEST. SHOULD HAVE SOME SNOW COVER AROUND...ESPECIALLY IN AREAS OF FAR SOUTHWEST NEBRASKA AND EASTERN COLORADO WHERE THE LAST 2 STORMS DUMPED THE MOST. WEDNESDAY...BY 00Z THURSDAY THE UPPER RIDGE AXIS SHOULD BE CENTERED ALONG THE CONTINENTAL DIVIDE WITH A NOTICEABLE INCREASE IN 850 TEMPERATURES AND THUS SURFACE TEMPERATURES. STILL THINKING SNOW COVER WILL EXIST ACROSS THE FAR NORTH AND PARTS OF FAR EASTERN COLORADO WHERE TEMPS HAVE BEEN TWEAKED CLOSER TO 40 DEGREES. ELSEWHERE...SNOW SHOULD JUST ABOUT BE GONE BY THIS TIME SO HAVE TRIED TO INCORPORATE STANDARD 850 TEMP BIAS` FOR THE ASOS SITES WHICH WOULD SUPPORT READINGS GENERALLY IN THE MID 40S. THURSDAY...850 TEMPERATURES CONTINUE TO WARM ABOUT 9F ACROSS THE AREA AS THE CENTER OF THE COUNTRY IS UNDER A BROAD UPPER LEVEL RIDGE WITH LOW PRESSURE AREAS OVER OR EAST OF THE EAST COAST AND ALONG OR WEST OF THE WEST COAST. FOR NOW SIMPLY ADDED 9 DEGREES TO WEDNESDAYS FORECAST HIGH GRID WHICH YIELDS THURSDAYS READINGS AROUND 50 NORTH AND WEST...LOW TO MID 50S ELSEWHERE. ECMWF WAS A BIT WARMER SO FURTHER TWEAKING WILL BE NEEDED...ESPECIALLY IF THE SNOW IS GONE BY THIS TIME. FRIDAY...UPPER FLOW SHIFTS TO THE SOUTHWEST AS THE WEST COAST UPPER TROUGH PUSHES INTO THE INTERMOUNTAIN WEST AND IN RETURN PUSHES THE RIDGE AXIS EAST OF THE AREA. 850 TEMPERATURES CONTINUE TO WARM JUST A BIT MORE. NO CHANGES WILL BE MADE BUT THE MOST OBVIOUS NEED MAY/WILL BE TO BUMP AFTERNOON TEMPERATURES UP JUST A FEW MORE DEGREES. && .AVIATION... FOR THE 12Z TAFS ONLY EXPECTING A FEW PERIODS OF MID LEVEL CLOUDS GENERALLY IN THE 20K FT RANGE. WINDS GENERALLY FROM THE WEST/SOUTHWEST AT 10 KTS OR SO. VFR THROUGH THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ DDT/DDT/DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 817 PM EST SUN DEC 30 2007 .UPDATE... MINOR BUT STILL WORTHY ADJUSTMENTS TO SNOW EXPECTATIONS FOR THE REST OF TONIGHT ARE COMING UP AS OUR HIGH POP LOW QPF SCENARIO CONTINUES TO UNFOLD. THE LEAD UPPER LEVEL DEFORMATION PATTERN BRUSHING OUR FAR EASTERN COUNTIES HAS A COUPLE MORE HOURS LEFT IN IT BEFORE FORCING TRANSITIONS TO THE WAVE SHEARING EASTWARD FROM THE CHICAGO AREA. THIS SYSTEM WILL BRUSH THE DETROIT AREA BUT MAINLY AFFECT THE INTERSTATE 69 CORRIDOR INTO THE OVERNIGHT HOURS. ALL OF THIS DYNAMIC FORCING IS ACTING IN A SIMILAR ENVIRONMENT OF LOW MOISTURE BUT ALSO LOW STATIC STABILITY OR EVEN SHALLOW LAYERS OF INSTABILITY IN THE MID LEVELS AS SHOWN IN MODEL CROSS SECTIONS. THE RESULTING MOISTURE WILL CONTINUE TO BATTLE DRY AIR IN THE LOW LEVELS, ESPECIALLY IN THE TRI CITIES, FOR THE DURATION OF THE EVENT. EXPECT THINGS TO TAPER OFF AROUND 3 AM AS THE UPPER WAVE SHEARS TO OUR EAST. UNTIL THEN, WE WILL HANG ON TO CATEGORICAL POPS A LITTLE FARTHER NORTH INTO FLINT AND A LONGER INTO THE NIGHT, BUT WITH SOME DURATION QUALIFIERS TO GO ALONG WITH ACCUMULATION LESS THAN AN INCH. && .PREV DISCUSSION...ISSUED 645 PM EST SUN DEC 30 2007 AVIATION... AREAL COVERAGE AND DURATION OF LIGHT SNOW WILL BE THE MAIN CONCERN EARLY THIS AVIATION FORECAST CYCLE. AT THIS POINT, IT LOOKS LIKE THE DETROIT AREA WILL BE IMPACTED MAINLY DURING THE EVENING HOURS WITH MVFR VISIBILITY AND CEILING IN LIGHT SNOW. IFR CONDITIONS WILL BE ON THE BRIEF SIDE AT ALL TERMINALS BUT FLINT AND TRI CITIES HAVE A CHANCE AT A LONGER DURATION MVFR SITUATION AS A SYSTEM OVER CHICAGO MOVES THROUGH CENTRAL LOWER MICHIGAN LATE THIS EVENING AND EARLY IN THE OVERNIGHT. THE SNOW WILL END LATE TONIGHT AND BE REPLACED BY STRATUS AND LIGHT FOG AS MOIST BOUNDARY LAYER AIR MOVES IN FROM ILLINOIS AND INDIANA. MVFR CONDITIONS WILL PERSIST INTO MONDAY AFTERNOON BEFORE GIVING WAY TO SLIGHT VISIBILITY IMPROVEMENT. SNOW FROM THE NEXT LOW PRESSURE SYSTEM IS EXPECTED TO HOLD OFF UNTIL MONDAY EVENING. PREV DISCUSSION...ISSUED 332 PM EST SUN DEC 30 2007 SHORT TERM...THROUGH TONIGHT HIGH POP/LOW QPF SNOW MINI-EVENT EXPECTED FOR THE SOUTHERN HALF OF THE FORECAST AREA TONIGHT...ROUGHLY SOUTH OF I-69. NORTH OF THERE...JUST SOME LIGHT SNOW SHOWERS. HIGHEST SNOW ACCUMULATIONS...ONLY ABOUT AN INCH...ARE EXPECTED TO OCCUR OVER THE FAR SOUTHEASTERN PORTION OF THE STATE...FROM ST CLAIR COUNTY SOUTHWARD DOWN TO MONROE COUNTY. UPPER TROUGH AXIS MOVING THROUGH THE CORN BELT THIS AFTERNOON WILL MOVE THROUGH THE GREAT LAKES DURING THE FIRST HALF OF NIGHT. WHILE MAIN SURFACE REFLECTION WILL STAY OVER THE CAROLINAS...PAST SEVERAL MODEL SUITES HAVE SHOWN A SECONDARY REFLECTION DEVELOPING OVER WEST VIRGINIA AND TRACKING UP THROUGH WESTERN PENNSYLVANIA DURING THE LATE EVENING. MSAS SURFACE ANALYSIS AND SURFACE OBSERVATIONS DO INDICATE THE PRESENCE OF THIS FEATURE...AND 12Z MODELS WERE DEFINITELY TOO WEAK WITH IT. ALREADY SOME EVIDENCE OF A DEFORMATION BAND FORMING ON THE NORTH SIDE OF THIS SYSTEM PER OBS AND SATELLITE IMAGERY...AND MODELS ARE IN GOOD AGREEMENT WITH BRINGING THIS DEFORMATION ZONE INTO SOUTHEAST MICHIGAN AFTER 00Z TONIGHT. SYSTEM WILL NOT HAVE MUCH TO WORK WITH AS JET DYNAMICS WILL REMAIN JUST TO OUR SOUTHEAST...AND NO DECENT INFLUX OF LOW LEVEL MOISTURE WILL OCCUR. WILL SEE SOME ISENTROPIC LIFT HOWEVER...AND FORCING DOES LOOK TO BE CENTERED IN THE DENDRITIC GROWTH ZONE ALLOWING FOR MAXIMUM CRYSTAL GROWTH. OVERALL...LIKE THE RUC AND NGM QPF FIELDS THE BEST. DID HOWEVER LEAN TOWARDS THE HIGHER END OF THE MODEL QPF FIELDS...GIVEN THAT THE MODELS ARE UNDERDONE WITH THE SYSTEM INTENSITY. WITH THE LOW CENTER ALREADY SO FAR TO OUR EAST SNOWFALL WILL BE LIGHT AND FAIRLY SHORT IN DURATION...MOSTLY OCCURRING WITHIN A 4 TO 6 HOUR WINDOW THIS EVENING. PRECIPITATION SHOULD BE OUT OF SOUTHEAST MICHIGAN BY 4 AM. IN THE WAKE OF THIS LITTLE SYSTEM...LOW CLOUDS AND MIST WILL LINGER THROUGH THE NIGHT. SOUTHWEST FLOW WILL ALSO BECOME ESTABLISHED LATE TONIGHT AS THE NEXT LOW PRESSURE SYSTEM OVER THE UPPER MIDWEST BECOMES BETTER ORGANIZED AND STARTS TO ADVANCE INTO THE WESTERN GREAT LAKES. LONG TERM... WATER VAPOR IMAGERY AND RUC ANALYSIS DEPICTING WEAK SHORTWAVE ENERGY EJECTING SOUTHEAST ACROSS THE PACIFIC NORTHWEST THIS AFTERNOON. THIS ENERGY WILL ORGANIZE INTO A STRONGER SHORTWAVE ACROSS THE PLAINS TONIGHT...AND EVENTUALLY INDUCE WEAK SFC CYCLOGENESIS AS IT PULLS TOWARD THE GREAT LAKES ON MONDAY. MODEL TRENDS SINCE THE 00Z CYCLE HAVE BEEN TOWARD A WEAKER AND MORE SOUTHERLY TRACK OF THE MAIN SFC LOW...WITH A SECOND WEAKER SFC REFLECTION INDICATED WITHIN THE UNPHASED FLOW ACROSS SOUTHERN CANADA. THE 12Z GFS...WITH SUPPORT FROM THE 12Z WRF-HEMI AND CANADIAN...TAKES THE LOW FROM CENTRAL IL ACROSS NORTHERN IN AND INTO LAKE ERIE. THE NAM REMAINS THE FURTHEST SOUTH...KEEPING A STRONGER/MORE COMPACT LOW ACROSS SOUTHERN IN/NORTHEAST OHIO. THE 12Z ECMWF APPEARS TO BE A GOOD COMPROMISE...MAINTAINING A SLIGHTLY MORE SOUTHERLY TRACK THAN THE GFS...WHILE ALLOWING FOR BETTER NORTHWARD EXPANSION OF THE MOISTURE/PCPN SHIELD INTO SOUTHEAST LOWER MI COMPARED TO THE VERY DRY LOOKING NAM. FORCING WILL BE LACKING INITIALLY...AND WILL PULL BACK ON POPS FOR THE MORNING HOURS. HOWEVER...BY LATE AFTERNOON/EVENING THE INCREASING LARGE SCALE ACCENT PROVIDED BY THE UPPER TROUGH AND WEAK LOW/MID LEVEL DEFORMATION WILL HELP OVERCOME A LIMITED MOISTURE SOURCE TO BRING SNOW TO ALL OF SOUTHEAST LOWER MI. MODELS INDICATE THE MAIN AXIS OF LARGE SCALE FORCING/OMEGA WILL EXIST JUST SOUTH OF THE STATE LINE...LEAVING THE HIGHEST QPF BANDS JUST OUT OF OUR AREA. HOWEVER...GIVEN THE ANTICIPATED LOW TRACK AND OVERALL VERTICAL MOTION/MOISTURE FIELDS...A BROAD 1-2 INCH SWATH OF SNOWFALL STILL SEEMS PLAUSIBLE BY 06Z MONDAY NIGHT...ESPECIALLY ACROSS THE SOUTHERN HALF. THE POTENTIAL DOES EXIST FOR HIGHER AMOUNTS APPROACHING 3 INCHES ACROSS THE SOUTHERN TWO TIER OF COUNTIES...AND WILL NEED TO MONITOR FOR A POSSIBLE NORTHWARD ADJUSTMENT IN THE TRACK AND BETTER FORCING. WHERE GOOD SYNOPTIC FORCING LACKS ACROSS THE THUMB REGION...SOME ADDITIONAL SNOWFALL MAY COME FROM LAKE EFFECT ENHANCEMENT. THE ONLY AREA THAT MAY STRUGGLE TO SEE MUCH SYNOPTIC ACCUMULATION WILL BE IN THE SAGINAW VALLEY...AND WILL SCALE BACK QPF/SNOW AMOUNTS SLIGHTLY HERE. 12Z MODEL SUITE REMAIN IN STRONG AGREEMENT AND CARRY GOOD RUN TO RUN CONTINUITY WITH THE PATTERN EVOLUTION BY MIDWEEK. THE WEAKER SYSTEM LIFTING THROUGH MONDAY WILL LEAD IN A STRONGER SHORTWAVE FOR TUESDAY...WITH THIS ENERGY CARVING OUT A DEEPER LONGWAVE TROUGH AND ALLOWING A BRIEF SHOT OF ARCTIC AIR TO SPILL IN FOR TUESDAY NIGHT/ WEDNESDAY. STRENGTHENING COLD AIR ADVECTION ON TUESDAY WITH 850 MB TEMPERATURES DROPPING BELOW -10C WILL CREATE MARGINALLY FAVORABLE CONDITIONS FOR LAKE ENHANCED SNOW SHOWERS DURING THE DAY. THE LATEST GFS INDICATING A NARROW CONVERGENCE ZONE DEVELOPING ACROSS THE EASTERN PORTION OF THE THUMB...WITH A SMALL WINDOW OF PREDOMINANT NORTH-NORTHEAST FLOW OVER LAKE HURON INCREASING THE POTENTIAL FOR HIGHER SNOW AMOUNTS IN THESE LOCATIONS LATE TUESDAY. MORE ORGANIZED ACTIVITY WILL DEVELOP BY TUESDAY EVENING AREAWIDE AS FORCING/CONVERGENCE INCREASES ALONG THE ARCTIC FRONTAL BOUNDARY DROPPING SOUTH ACROSS SOUTHERN MI...AND LIKELY POPS REMAIN APPROPRIATE FOR THIS PERIOD. OVERALL...ADDITIONAL ACCUMULATIONS UP TO 2 INCHES (HIGHEST NORTH) STILL SEEMS REASONABLE AREAWIDE...WITH LOCALLY HIGHER AMOUNTS POSSIBLE ESPECIALLY IN THE FAVORED LAKE ENHANCED AREAS ACROSS THE THUMB. ARCTIC AIRMASS WILL SETTLE OVERHEAD BRIEFLY FOR WEDNESDAY...WITH LINGERING SCATTERED SNOW SHOWERS. BASED ON PROJECTED 850 MB/ THICKNESS TRENDS...TEMPERATURES WILL LIKELY HOLD STEADY OR SLOWLY FALL...AND NOT REACH MUCH ABOVE THE LOWER 20S. AT LEAST PARTIAL CLEARING WEDNESDAY NIGHT...COMBINED WITH A WEAKENING GRADIENT WITH HIGH PRESSURE BUILDING ACROSS THE OHIO VALLEY...WILL BRING THE COLDEST NIGHT OF THE FORECAST PERIOD. GOING FORECAST WITH LOWS BOTTOMING OUT IN THE 5-10F RANGE STILL LOOKING GOOD FOR THURSDAY MORNING. BIG PATTERN CHANGE FOR THE LATTER HALF OF THE FORECAST PERIOD...AS MODEL CONSENSUS PLACES THE GREAT LAKES WITHIN AN INCREASINGLY DEEP SOUTHWEST FLOW...BETWEEN STRENGTHENING RIDGING ACROSS THE EAST COAST AND A LONGWAVE TROUGH OVER THE WESTERN THIRD OF THE CONUS. THIS WILL LEAD TO A PRONOUNCED WARMUP BY THE WEEKEND...WITH 850 MB TEMPS CLIMBING INTO THE 5-10C RANGE BY SUNDAY. IT WILL TAKE SOME TIME TO SCOUR OUT THE ARCTIC AIR INITIALLY...AND WILL CONTINUE TO TEMPER THE WARMUP ON THURSDAY...AS THE COLD MORNING START AND SNOW COVER POTENTIAL WILL CERTAINLY COUNTER ANY INCREASE IN WARM AIR ADVECTION/ RISING THICKNESSES. HOWEVER...BY THE WEEKEND EXPECT TEMPERATURES TO CLIMB WELL ABOVE NORMAL...WITH HIGHS ON SUNDAY POTENTIALLY APPROACHING 50F ACROSS THE SOUTH. INCREASING ISENTROPIC ACCENT AND THE PASSAGE OF A WEAK SHORTWAVE WILL BRING THE NEXT CHANCE OF PCPN BY SATURDAY...WITH THE THERMAL PROFILES LOOKING MORE LIKE ALL RAIN. MARINE... AN AREA OF LOW PRESSURE WILL BECOME ORGANIZED OVER THE UPPER MIDWEST TONIGHT. THIS SYSTEM WILL DEEPEN AS IT MOVES ACROSS THE SOUTHERN GREAT LAKES MONDAY NIGHT...AND CONTINUE TO INTENSIFY THROUGH TUESDAY AS IT TRACKS INTO NEW ENGLAND. MEANWHILE...A VERY LARGE AND STRONG AREA OF HIGH PRESSURE WILL BUILD IN ITS WAKE TUESDAY OVER THE CENTRAL PLAINS. WITH OUR AREA IN THE CENTER OF THESE TWO STRENGTHENING SYSTEMS...A PROLONGED PERIOD OF GUSTY WINDS WILL OCCUR OVER ALL MARINE AREAS TUESDAY MORNING THROUGH WEDNESDAY EVENING. WINDS ARE EXPECTED TO REMAIN BELOW GALE STRENGTH...BUT SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......BT AVIATION.....BT SHORT TERM...HLO LONG TERM....MR MARINE.......HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 648 PM EST SUN DEC 30 2007 .SHORT TERM...(TONIGHT AND MONDAY) MAIN FCST CONCERNS ARE LIGHT SNOW CHANCES MONDAY. WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD TROF OVER THE CONUS WITH THE MAIN BAROCLINIC ZONE AND JET ENERGY WELL TO THE SOUTH. SEVERAL WEAK SHORTWAVES WERE EMBEDDED IN THE WEAKER FLOW FROM THE PLAINS INTO THE UPPER GREAT LAKES. ONE WAS MOVING THROUGH NW MN WHILE ANOTHER WEAK SHORTWAVE WAS IN LINE OVER SE SASKATCHEWAN AHEAD OF A STRONGER SHORTWAVE OVER NRN SASK. AT THE SFC...WEAK SRLY FLOW PREVAILED OVER UPPER MI AS A WEAK TROUGH EXTENDED INTO NRN LAKE SUPERIOR FROM LOW PRES OVER NW MN AND THE ERN DAKOTAS. VIS LOOP SHOWED THAT CLEAR PATCHES THAT HAD DEVELOPED WERE GIVING WAY TO INCREASING CLOUDS WITH CONTINUED LOW LEVEL MOISTURE ADVECTION FROM WI. SSW FLOW OFF OF LAKE MI HAS BROUGHT SCT -SHSN TO THE ERN CWA FROM E OF KISQ TO KERY. TONIGHT...EXPECT LITTLE MORE THAN PATCHY FLURRIES THIS EVENING WITH ONLY WEAK WAA AND LOW LEVEL (925-850 MB LAYER) ISENTROPIC LIFT CONTINUING. ONLY SLIGHT CHANCE POPS INCLUDED OVERNIGHT AS WAA/ISENTROPIC LIFT INCREASE AND 850-700 MOISTURE INCREASES AHEAD OF THE TROUGH MOVING IN FROM THE ERN DAKOTAS. LIGHT LES INTO THE ERN CWA SHOULD ALSO DIMINISH THIS EVENING AS THE LOW LEVEL WINDS BECOME LIGHT AND DISORGANIZED. THE NAM AND LCL HIGH RES WRF/ARW ALSO SUGGEST THAT THE MORE FAVORABLE LOW LEVEL CONV WILL SHIFT EAST OF THE CWA OVERNIGHT. MONDAY...MODELS DEPICTION OF A 850-700 MB SHORTWAVE...STRONGEST WITH THE GFS...WOULD BRING ADDITIONAL BAND OF 280-285K ISENTROPIC LIFT AND POTENTIAL FOR LIGHT SNOW ACROSS THE AREA. SNOW CHANCES WILL INCREASE LATE ACROSS THE WEST AS WINDS VEER WNW. 850 MB TEMPS DOWN TO NEAR -13C WITH DEEP MOISTURE AND CYCLONIC FLOW WILL SUPPORT SOME LIGHT LES OR LAKE ENHANCED SNOW LATE. WITH LATE ONSET ACCUMULATIONS BY EVENING SHOULD STILL REMAIN AN INCH OR LESS. .LONG TERM (MON NIGHT THRU SUN)... MAIN FCST CONCERN IS THE LAKE EFFECT SNOW EVENT MON NIGHT THRU TUE NIGHT. THE LAST FEW MODELS RUNS HAVE SHOWN A SHARP SFC TROF DROPPING S ACROSS LAKE SUPERIOR MON NIGHT/TUE MORNING IN RESPONSE TO A SHORTWAVE DIVING FROM THE NRN PLAINS TO THE OHIO VALLEY. WHILE BEST FORCING WITH SHORWAVE WILL PASS W AND S OF THE FCST AREA... CONDITIONS WILL STILL BE FAVORABLE FOR A PERIOD OF MDT TO POSSIBLY HVY LAKE ENHANCED SNOW LATE MON NIGHT/TUE AS MIDLEVEL TROF AXIS PASSES. DEVELOPING SFC TROF OVER LAKE SUPERIOR MON NIGHT WILL LEAD TO INCREASINGLY CYCLONIC FLOW OVER THE LAKE WITH W TO NW WINDS AHEAD OF TROF FAVORING THE WRN COUNTIES FOR DEVELOPING LAKE ENHANCED SNOW. FOR THE MOST PART...WRLY WINDS OVER NCNTRL UPPER MI WILL KEEP MAIN SNOW AREA OFFSHORE UNTIL TROF PASSAGE TUE MORNING. ONCE WINDS SHIFT NRLY BEHIND TROF EARLY TUE MORNING...EXPECT HEAVIEST SNOW TO SETTLE OVER WRN GOGEBIC/ONTONAGON COUNTIES AND MARQUETTE/WRN ALGER COUNTIES. DEEP MOISTURE...CYCLONIC UPSLOPE FLOW AND MODEL TIME SECTIONS SHOWING A NICE INTERSECTION OF UPWARD MOTION WITHIN FALLING LAYER OF FAVORABLE DENDRITIC SNOW GROWTH TEMPS UNDER CAA REGIME SUGGEST THIS EVENT MAY REACH WARNING CRITERIA (8 INCHES IN 12HRS OR 10 IN 24HRS) IN SOME LOCATIONS. CONFIDENCE AT THIS POINT IS JUST SUFFICIENT ENOUGH TO ISSUE WATCHES. HAVE STARTED LAKE EFFECT SNOW WATCH AT 00Z TUE OVER THE WRN COUNTIES SINCE FLOW IS W TO NW AHEAD OF SFC TROF. HOWEVER...SNOW SHOULDN`T REALLY PICK UP UNTIL AFTER MIDNIGHT. STARTED WATCH AT 12Z TUE FOR MARQUETTE/ALGER COUNTIES WITH EXPECTATION OF WIND SHIFT TO THE N ARRIVING NEAR THAT TIME. LEFT LUCE COUNTY OUT OF WATCH SINCE WINDS SHIFT N TO NE MINIMIZING OVERWATER TRAJECTORY THERE. ALSO...OPTED TO LEAVE BARAGA COUNTY OUT OF WATCH DUE TO SHORTER PERIOD OF FAVORABLE WIND DIRECTION THERE. AT THIS TIME...IT APPEARS GOGEBIC/ONTONAGON COUNTIES WILL SEE THE GREATEST SNOW ACCUMULATIONS (AND MOST LIKELY TO REACH WARNING AMOUNTS) FROM THIS EVENT DUE TO LONGEST PERIOD OF FAVORABLE WIND DIRECTION AND DUE TO AIRMASS PASSING OVER WRN LAKE SUPERIOR BEING COLDER. TIME PERIOD OF HEAVIEST SNOW SHOULD BE AFTER MIDNIGHT INTO EARLY TUE MORNING FOR THE KEWEENAW...AFTER MIDNIGHT MON THRU TUE AFTN FOR GOGEBIC/ONTONAGON AND DURING THE DAY TUE FOR MARQUETTE/ALGER. ALTHOUGH WATCHES WILL RUN TO 12Z WED...SNOW WILL BE QUITE A BIT LIGHTER DURING THE PURE LES PHASE TUE NIGHT. HIGH PRES RIDGE WILL BUILD INTO THE WRN LAKES WED AND PASS THRU THE AREA WED NIGHT...BRINGING AN END TO LES FROM W TO E AS WINDS BACK FROM NW TO SW. TEMPS WILL HAVE AN OPPORTUNITY TO PLUMMET DURING THE SHORT PERIOD OF RIDGE PASSAGE WED NIGHT. READINGS COULD BE SEVERAL DEGREES LOWER THAN WHAT THIS FCST ISSUANCE REFLECTS. FOR NOW...HAVE MIN TEMPS AT OR JUST BLO ZERO OVER MUCH OF THE INTERIOR. THU THRU SUN...UNFORTUNATELY FOR THOSE WHO ENJOY WINTER SNOW ACTIVITIES...THE LONG ADVERTISED GFS/ECWMF CHANGE IN THE PATTERN TO A MAJOR WARMUP TO WELL ABOVE NORMAL TEMPS WILL BE UNDERWAY DURING THIS PERIOD AS MEAN TROF POSITION SETTLES INTO THE FAR ERN PACIFIC/WRN NAMERICA AND RIDGE BUILDS OVER ERN NAMERICA. BEYOND THIS FCST PERIOD INTO EARLY NEXT WEEK...UNUSUAL WARMTH IS LIKELY TO PERSIST. LOOKS LIKE SOME RECORD HIGH MAX TEMPS AND RECORD HIGH MIN TEMPS WILL BE SET DURING THIS WARM PERIOD. MIN TEMP RECORDS WILL BE MORE LIKELY TO BE SET AS MINS WILL BE ESPECIALLY AFFECTED BY THE WARMING...SHOWING INCREASINGLY GREATER DEPARTURES FROM NORMAL THAN MAX TEMPS AS THE WARMING TREND LENGTHENS AND CLOUDS/INCREASINGLY MOIST AIRMASS LIMIT TEMP FALLS AT NIGHT. SHOULD SEE A COUPLE OF DAYS WHERE TEMPS DON`T FALL BACK BLO FREEZING. AS FOR PCPN...HAVE OPTED TO MAINTAIN CONTINUITY WITH THE LAST COUPLE OF DAYS OF FCSTS WITH REGARD TO LOW POPS FOR -SN THU/THU NIGHT. ALTHOUGH GFS/ECMWF SUGGEST A RATHER DRY AIRMASS...STRONG WAA PATTERN (850MB WINDS TO 50KT OVER UPPER MI RESULTING FROM SHORTWAVE TRACKING THRU NRN ONTARIO/HUDSON BAY REGION) IS SUPPORTIVE OF MAINTAINING A MENTION OF POSSIBLE -SN FOR ONE MORE FCST ISSUANCE. FIRST SHORTWAVE HEADING NE FROM THE NEW E PACIFIC/WRN N AMERICA TROF SHOULD MAKE A RUN ACROSS THE PLAINS TO THE GREAT LAKES FRI NIGHT/SAT...BRINGING SOME -RN...WHICH WILL LIKELY BEGIN AS -SN/-FZRA FRI NIGHT. ANOTHER SHORTWAVE AND SURGE OF WAA WILL BRING ANOTHER ROUND OF PCPN SUN. SHOULD BE ALL RAIN AT THAT TIME AS LOW-LEVEL WARM AIR WILL BE ESTABLISHED BY THEN PER GFS/ECWMF. BEYOND THIS FCST PERIOD...THERE HAVE BEEN INDICATIONS IN SEVERAL OF THE RECENT GFS/ECMWF RUNS THAT A SIGNIFICANT RAIN EVENT (MAY INCLUDE THUNDERSTORMS AS WELL) WILL OCCUR AT SOME POINT DURING THE FIRST HALF OF NEXT WEEK. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... MVFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD AT KSAW AND MOST OF THE PERIOD AT KCMX. WHEN THE SNOW STARTS AT KCMX IN THE AFTERNOON AND THE WIND SWINGS AROUND TO THE WEST...LAKE ENHANCEMENT WILL BEGIN AND CONDITIONS WILL GO TO IFR TO LIFR LATE IN THE AFTERNOON. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A WEAK HIGH PRESSURE OVER THE EASTERN LAKES WILL GIVE WAY TO A DEVELOPING TROUGH OVER THE UPPER GREAT LAKES MONDAY. AS A RESULT... WINDS SHOULD REMAIN BLO 25 KNOTS. A LOW OVER LAKE SUPERIOR MONDAY NIGHT WILL SLIDE QUICKLY TO THE SOUTHEAST AS A STRONG HIGH PRESSURE OVER THE PLAINS BUILDS TOWARD THE AREA. A TIGHT PRES GRADIENT BETWEEN THESE FEATURES WILL BRING A PERIOD OF NORTHERLY GALES TUESDAY AS STRONG CAA RESULTS IN STRONG BOUNDARY LAYER MIXING. LOOK FOR WINDS TO DIMINISH TO BLO 25 KTS BY WED EVENING AS THE HIGH PRES RIDGE FROM THE PLAINS MOVES OVER THE REGION. SOUTHERLY GALES ARE POSSIBLE THU AFTERNOON AND EVENING AS A LOW-LEVEL JET CORE DEVELOPS OVER THE REGION AHEAD OF ANOTHER NORTHERN PLAINS TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WATCH 00Z TUE TO 12Z WED MIZ001>003-009-084. LAKE EFFECT SNOW WATCH 12Z TUE TO 12Z WED MIZ005-006. && $$ SHORT TERM...JLB LONG TERM...ROLFSON AVIATION...JLB MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 645 PM EST SUN DEC 30 2007 .AVIATION... AREAL COVERAGE AND DURATION OF LIGHT SNOW WILL BE THE MAIN CONCERN EARLY THIS AVIATION FORECAST CYCLE. AT THIS POINT, IT LOOKS LIKE THE DETROIT AREA WILL BE IMPACTED MAINLY DURING THE EVENING HOURS WITH MVFR VISIBILITY AND CEILING IN LIGHT SNOW. IFR CONDITIONS WILL BE ON THE BRIEF SIDE AT ALL TERMINALS BUT FLINT AND TRI CITIES HAVE A CHANCE AT A LONGER DURATION MVFR SITUATION AS A SYSTEM OVER CHICAGO MOVES THROUGH CENTRAL LOWER MICHIGAN LATE THIS EVENING AND EARLY IN THE OVERNIGHT. THE SNOW WILL END LATE TONIGHT AND BE REPLACED BY STRATUS AND LIGHT FOG AS MOIST BOUNDARY LAYER AIR MOVES IN FROM ILLINOIS AND INDIANA. MVFR CONDITIONS WILL PERSIST INTO MONDAY AFTERNOON BEFORE GIVING WAY TO SLIGHT VISIBILITY IMPROVEMENT. SNOW FROM THE NEXT LOW PRESSURE SYSTEM IS EXPECTED TO HOLD OFF UNTIL MONDAY EVENING. && .PREV DISCUSSION...ISSUED 332 PM EST SUN DEC 30 2007 SHORT TERM...THROUGH TONIGHT HIGH POP/LOW QPF SNOW MINI-EVENT EXPECTED FOR THE SOUTHERN HALF OF THE FORECAST AREA TONIGHT...ROUGHLY SOUTH OF I-69. NORTH OF THERE...JUST SOME LIGHT SNOW SHOWERS. HIGHEST SNOW ACCUMULATIONS...ONLY ABOUT AN INCH...ARE EXPECTED TO OCCUR OVER THE FAR SOUTHEASTERN PORTION OF THE STATE...FROM ST CLAIR COUNTY SOUTHWARD DOWN TO MONROE COUNTY. UPPER TROUGH AXIS MOVING THROUGH THE CORN BELT THIS AFTERNOON WILL MOVE THROUGH THE GREAT LAKES DURING THE FIRST HALF OF NIGHT. WHILE MAIN SURFACE REFLECTION WILL STAY OVER THE CAROLINAS...PAST SEVERAL MODEL SUITES HAVE SHOWN A SECONDARY REFLECTION DEVELOPING OVER WEST VIRGINIA AND TRACKING UP THROUGH WESTERN PENNSYLVANIA DURING THE LATE EVENING. MSAS SURFACE ANALYSIS AND SURFACE OBSERVATIONS DO INDICATE THE PRESENCE OF THIS FEATURE...AND 12Z MODELS WERE DEFINITELY TOO WEAK WITH IT. ALREADY SOME EVIDENCE OF A DEFORMATION BAND FORMING ON THE NORTH SIDE OF THIS SYSTEM PER OBS AND SATELLITE IMAGERY...AND MODELS ARE IN GOOD AGREEMENT WITH BRINGING THIS DEFORMATION ZONE INTO SOUTHEAST MICHIGAN AFTER 00Z TONIGHT. SYSTEM WILL NOT HAVE MUCH TO WORK WITH AS JET DYNAMICS WILL REMAIN JUST TO OUR SOUTHEAST...AND NO DECENT INFLUX OF LOW LEVEL MOISTURE WILL OCCUR. WILL SEE SOME ISENTROPIC LIFT HOWEVER...AND FORCING DOES LOOK TO BE CENTERED IN THE DENDRITIC GROWTH ZONE ALLOWING FOR MAXIMUM CRYSTAL GROWTH. OVERALL...LIKE THE RUC AND NGM QPF FIELDS THE BEST. DID HOWEVER LEAN TOWARDS THE HIGHER END OF THE MODEL QPF FIELDS...GIVEN THAT THE MODELS ARE UNDERDONE WITH THE SYSTEM INTENSITY. WITH THE LOW CENTER ALREADY SO FAR TO OUR EAST SNOWFALL WILL BE LIGHT AND FAIRLY SHORT IN DURATION...MOSTLY OCCURRING WITHIN A 4 TO 6 HOUR WINDOW THIS EVENING. PRECIPITATION SHOULD BE OUT OF SOUTHEAST MICHIGAN BY 4 AM. IN THE WAKE OF THIS LITTLE SYSTEM...LOW CLOUDS AND MIST WILL LINGER THROUGH THE NIGHT. SOUTHWEST FLOW WILL ALSO BECOME ESTABLISHED LATE TONIGHT AS THE NEXT LOW PRESSURE SYSTEM OVER THE UPPER MIDWEST BECOMES BETTER ORGANIZED AND STARTS TO ADVANCE INTO THE WESTERN GREAT LAKES. LONG TERM... WATER VAPOR IMAGERY AND RUC ANALYSIS DEPICTING WEAK SHORTWAVE ENERGY EJECTING SOUTHEAST ACROSS THE PACIFIC NORTHWEST THIS AFTERNOON. THIS ENERGY WILL ORGANIZE INTO A STRONGER SHORTWAVE ACROSS THE PLAINS TONIGHT...AND EVENTUALLY INDUCE WEAK SFC CYCLOGENESIS AS IT PULLS TOWARD THE GREAT LAKES ON MONDAY. MODEL TRENDS SINCE THE 00Z CYCLE HAVE BEEN TOWARD A WEAKER AND MORE SOUTHERLY TRACK OF THE MAIN SFC LOW...WITH A SECOND WEAKER SFC REFLECTION INDICATED WITHIN THE UNPHASED FLOW ACROSS SOUTHERN CANADA. THE 12Z GFS...WITH SUPPORT FROM THE 12Z WRF-HEMI AND CANADIAN...TAKES THE LOW FROM CENTRAL IL ACROSS NORTHERN IN AND INTO LAKE ERIE. THE NAM REMAINS THE FURTHEST SOUTH...KEEPING A STRONGER/MORE COMPACT LOW ACROSS SOUTHERN IN/NORTHEAST OHIO. THE 12Z ECMWF APPEARS TO BE A GOOD COMPROMISE...MAINTAINING A SLIGHTLY MORE SOUTHERLY TRACK THAN THE GFS...WHILE ALLOWING FOR BETTER NORTHWARD EXPANSION OF THE MOISTURE/PCPN SHIELD INTO SOUTHEAST LOWER MI COMPARED TO THE VERY DRY LOOKING NAM. FORCING WILL BE LACKING INITIALLY...AND WILL PULL BACK ON POPS FOR THE MORNING HOURS. HOWEVER...BY LATE AFTERNOON/EVENING THE INCREASING LARGE SCALE ACCENT PROVIDED BY THE UPPER TROUGH AND WEAK LOW/MID LEVEL DEFORMATION WILL HELP OVERCOME A LIMITED MOISTURE SOURCE TO BRING SNOW TO ALL OF SOUTHEAST LOWER MI. MODELS INDICATE THE MAIN AXIS OF LARGE SCALE FORCING/OMEGA WILL EXIST JUST SOUTH OF THE STATE LINE...LEAVING THE HIGHEST QPF BANDS JUST OUT OF OUR AREA. HOWEVER...GIVEN THE ANTICIPATED LOW TRACK AND OVERALL VERTICAL MOTION/MOISTURE FIELDS...A BROAD 1-2 INCH SWATH OF SNOWFALL STILL SEEMS PLAUSIBLE BY 06Z MONDAY NIGHT...ESPECIALLY ACROSS THE SOUTHERN HALF. THE POTENTIAL DOES EXIST FOR HIGHER AMOUNTS APPROACHING 3 INCHES ACROSS THE SOUTHERN TWO TIER OF COUNTIES...AND WILL NEED TO MONITOR FOR A POSSIBLE NORTHWARD ADJUSTMENT IN THE TRACK AND BETTER FORCING. WHERE GOOD SYNOPTIC FORCING LACKS ACROSS THE THUMB REGION...SOME ADDITIONAL SNOWFALL MAY COME FROM LAKE EFFECT ENHANCEMENT. THE ONLY AREA THAT MAY STRUGGLE TO SEE MUCH SYNOPTIC ACCUMULATION WILL BE IN THE SAGINAW VALLEY...AND WILL SCALE BACK QPF/SNOW AMOUNTS SLIGHTLY HERE. 12Z MODEL SUITE REMAIN IN STRONG AGREEMENT AND CARRY GOOD RUN TO RUN CONTINUITY WITH THE PATTERN EVOLUTION BY MIDWEEK. THE WEAKER SYSTEM LIFTING THROUGH MONDAY WILL LEAD IN A STRONGER SHORTWAVE FOR TUESDAY...WITH THIS ENERGY CARVING OUT A DEEPER LONGWAVE TROUGH AND ALLOWING A BRIEF SHOT OF ARCTIC AIR TO SPILL IN FOR TUESDAY NIGHT/ WEDNESDAY. STRENGTHENING COLD AIR ADVECTION ON TUESDAY WITH 850 MB TEMPERATURES DROPPING BELOW -10C WILL CREATE MARGINALLY FAVORABLE CONDITIONS FOR LAKE ENHANCED SNOW SHOWERS DURING THE DAY. THE LATEST GFS INDICATING A NARROW CONVERGENCE ZONE DEVELOPING ACROSS THE EASTERN PORTION OF THE THUMB...WITH A SMALL WINDOW OF PREDOMINANT NORTH-NORTHEAST FLOW OVER LAKE HURON INCREASING THE POTENTIAL FOR HIGHER SNOW AMOUNTS IN THESE LOCATIONS LATE TUESDAY. MORE ORGANIZED ACTIVITY WILL DEVELOP BY TUESDAY EVENING AREAWIDE AS FORCING/CONVERGENCE INCREASES ALONG THE ARCTIC FRONTAL BOUNDARY DROPPING SOUTH ACROSS SOUTHERN MI...AND LIKELY POPS REMAIN APPROPRIATE FOR THIS PERIOD. OVERALL...ADDITIONAL ACCUMULATIONS UP TO 2 INCHES (HIGHEST NORTH) STILL SEEMS REASONABLE AREAWIDE...WITH LOCALLY HIGHER AMOUNTS POSSIBLE ESPECIALLY IN THE FAVORED LAKE ENHANCED AREAS ACROSS THE THUMB. ARCTIC AIRMASS WILL SETTLE OVERHEAD BRIEFLY FOR WEDNESDAY...WITH LINGERING SCATTERED SNOW SHOWERS. BASED ON PROJECTED 850 MB/ THICKNESS TRENDS...TEMPERATURES WILL LIKELY HOLD STEADY OR SLOWLY FALL...AND NOT REACH MUCH ABOVE THE LOWER 20S. AT LEAST PARTIAL CLEARING WEDNESDAY NIGHT...COMBINED WITH A WEAKENING GRADIENT WITH HIGH PRESSURE BUILDING ACROSS THE OHIO VALLEY...WILL BRING THE COLDEST NIGHT OF THE FORECAST PERIOD. GOING FORECAST WITH LOWS BOTTOMING OUT IN THE 5-10F RANGE STILL LOOKING GOOD FOR THURSDAY MORNING. BIG PATTERN CHANGE FOR THE LATTER HALF OF THE FORECAST PERIOD...AS MODEL CONSENSUS PLACES THE GREAT LAKES WITHIN AN INCREASINGLY DEEP SOUTHWEST FLOW...BETWEEN STRENGTHENING RIDGING ACROSS THE EAST COAST AND A LONGWAVE TROUGH OVER THE WESTERN THIRD OF THE CONUS. THIS WILL LEAD TO A PRONOUNCED WARMUP BY THE WEEKEND...WITH 850 MB TEMPS CLIMBING INTO THE 5-10C RANGE BY SUNDAY. IT WILL TAKE SOME TIME TO SCOUR OUT THE ARCTIC AIR INITIALLY...AND WILL CONTINUE TO TEMPER THE WARMUP ON THURSDAY...AS THE COLD MORNING START AND SNOW COVER POTENTIAL WILL CERTAINLY COUNTER ANY INCREASE IN WARM AIR ADVECTION/ RISING THICKNESSES. HOWEVER...BY THE WEEKEND EXPECT TEMPERATURES TO CLIMB WELL ABOVE NORMAL...WITH HIGHS ON SUNDAY POTENTIALLY APPROACHING 50F ACROSS THE SOUTH. INCREASING ISENTROPIC ACCENT AND THE PASSAGE OF A WEAK SHORTWAVE WILL BRING THE NEXT CHANCE OF PCPN BY SATURDAY...WITH THE THERMAL PROFILES LOOKING MORE LIKE ALL RAIN. MARINE... AN AREA OF LOW PRESSURE WILL BECOME ORGANIZED OVER THE UPPER MIDWEST TONIGHT. THIS SYSTEM WILL DEEPEN AS IT MOVES ACROSS THE SOUTHERN GREAT LAKES MONDAY NIGHT...AND CONTINUE TO INTENSIFY THROUGH TUESDAY AS IT TRACKS INTO NEW ENGLAND. MEANWHILE...A VERY LARGE AND STRONG AREA OF HIGH PRESSURE WILL BUILD IN ITS WAKE TUESDAY OVER THE CENTRAL PLAINS. WITH OUR AREA IN THE CENTER OF THESE TWO STRENGTHENING SYSTEMS...A PROLONGED PERIOD OF GUSTY WINDS WILL OCCUR OVER ALL MARINE AREAS TUESDAY MORNING THROUGH WEDNESDAY EVENING. WINDS ARE EXPECTED TO REMAIN BELOW GALE STRENGTH...BUT SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT SHORT TERM...HLO LONG TERM....MR MARINE.......HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 332 PM EST SUN DEC 30 2007 .SHORT TERM...THROUGH TONIGHT HIGH POP/LOW QPF SNOW MINI-EVENT EXPECTED FOR THE SOUTHERN HALF OF THE FORECAST AREA TONIGHT...ROUGHLY SOUTH OF I-69. NORTH OF THERE...JUST SOME LIGHT SNOW SHOWERS. HIGHEST SNOW ACCUMULATIONS...ONLY ABOUT AN INCH...ARE EXPECTED TO OCCUR OVER THE FAR SOUTHEASTERN PORTION OF THE STATE...FROM ST CLAIR COUNTY SOUTHWARD DOWN TO MONROE COUNTY. UPPER TROUGH AXIS MOVING THROUGH THE CORN BELT THIS AFTERNOON WILL MOVE THROUGH THE GREAT LAKES DURING THE FIRST HALF OF NIGHT. WHILE MAIN SURFACE REFLECTION WILL STAY OVER THE CAROLINAS...PAST SEVERAL MODEL SUITES HAVE SHOWN A SECONDARY REFLECTION DEVELOPING OVER WEST VIRGINIA AND TRACKING UP THROUGH WESTERN PENNSYLVANIA DURING THE LATE EVENING. MSAS SURFACE ANALYSIS AND SURFACE OBSERVATIONS DO INDICATE THE PRESENCE OF THIS FEATURE...AND 12Z MODELS WERE DEFINITELY TOO WEAK WITH IT. ALREADY SOME EVIDENCE OF A DEFORMATION BAND FORMING ON THE NORTH SIDE OF THIS SYSTEM PER OBS AND SATELLITE IMAGERY...AND MODELS ARE IN GOOD AGREEMENT WITH BRINGING THIS DEFORMATION ZONE INTO SOUTHEAST MICHIGAN AFTER 00Z TONIGHT. SYSTEM WILL NOT HAVE MUCH TO WORK WITH AS JET DYNAMICS WILL REMAIN JUST TO OUR SOUTHEAST...AND NO DECENT INFLUX OF LOW LEVEL MOISTURE WILL OCCUR. WILL SEE SOME ISENTROPIC LIFT HOWEVER...AND FORCING DOES LOOK TO BE CENTERED IN THE DENDRITIC GROWTH ZONE ALLOWING FOR MAXIMUM CRYSTAL GROWTH. OVERALL...LIKE THE RUC AND NGM QPF FIELDS THE BEST. DID HOWEVER LEAN TOWARDS THE HIGHER END OF THE MODEL QPF FIELDS...GIVEN THAT THE MODELS ARE UNDERDONE WITH THE SYSTEM INTENSITY. WITH THE LOW CENTER ALREADY SO FAR TO OUR EAST SNOWFALL WILL BE LIGHT AND FAIRLY SHORT IN DURATION...MOSTLY OCCURRING WITHIN A 4 TO 6 HOUR WINDOW THIS EVENING. PRECIPITATION SHOULD BE OUT OF SOUTHEAST MICHIGAN BY 4 AM. IN THE WAKE OF THIS LITTLE SYSTEM...LOW CLOUDS AND MIST WILL LINGER THROUGH THE NIGHT. SOUTHWEST FLOW WILL ALSO BECOME ESTABLISHED LATE TONIGHT AS THE NEXT LOW PRESSURE SYSTEM OVER THE UPPER MIDWEST BECOMES BETTER ORGANIZED AND STARTS TO ADVANCE INTO THE WESTERN GREAT LAKES. && .LONG TERM... WATER VAPOR IMAGERY AND RUC ANALYSIS DEPICTING WEAK SHORTWAVE ENERGY EJECTING SOUTHEAST ACROSS THE PACIFIC NORTHWEST THIS AFTERNOON. THIS ENERGY WILL ORGANIZE INTO A STRONGER SHORTWAVE ACROSS THE PLAINS TONIGHT...AND EVENTUALLY INDUCE WEAK SFC CYCLOGENESIS AS IT PULLS TOWARD THE GREAT LAKES ON MONDAY. MODEL TRENDS SINCE THE 00Z CYCLE HAVE BEEN TOWARD A WEAKER AND MORE SOUTHERLY TRACK OF THE MAIN SFC LOW...WITH A SECOND WEAKER SFC REFLECTION INDICATED WITHIN THE UNPHASED FLOW ACROSS SOUTHERN CANADA. THE 12Z GFS...WITH SUPPORT FROM THE 12Z WRF-HEMI AND CANADIAN...TAKES THE LOW FROM CENTRAL IL ACROSS NORTHERN IN AND INTO LAKE ERIE. THE NAM REMAINS THE FURTHEST SOUTH...KEEPING A STRONGER/MORE COMPACT LOW ACROSS SOUTHERN IN/NORTHEAST OHIO. THE 12Z ECMWF APPEARS TO BE A GOOD COMPROMISE...MAINTAINING A SLIGHTLY MORE SOUTHERLY TRACK THAN THE GFS...WHILE ALLOWING FOR BETTER NORTHWARD EXPANSION OF THE MOISTURE/PCPN SHIELD INTO SOUTHEAST LOWER MI COMPARED TO THE VERY DRY LOOKING NAM. FORCING WILL BE LACKING INITIALLY...AND WILL PULL BACK ON POPS FOR THE MORNING HOURS. HOWEVER...BY LATE AFTERNOON/EVENING THE INCREASING LARGE SCALE ACCENT PROVIDED BY THE UPPER TROUGH AND WEAK LOW/MID LEVEL DEFORMATION WILL HELP OVERCOME A LIMITED MOISTURE SOURCE TO BRING SNOW TO ALL OF SOUTHEAST LOWER MI. MODELS INDICATE THE MAIN AXIS OF LARGE SCALE FORCING/OMEGA WILL EXIST JUST SOUTH OF THE STATE LINE...LEAVING THE HIGHEST QPF BANDS JUST OUT OF OUR AREA. HOWEVER...GIVEN THE ANTICIPATED LOW TRACK AND OVERALL VERTICAL MOTION/MOISTURE FIELDS...A BROAD 1-2 INCH SWATH OF SNOWFALL STILL SEEMS PLAUSIBLE BY 06Z MONDAY NIGHT...ESPECIALLY ACROSS THE SOUTHERN HALF. THE POTENTIAL DOES EXIST FOR HIGHER AMOUNTS APPROACHING 3 INCHES ACROSS THE SOUTHERN TWO TIER OF COUNTIES...AND WILL NEED TO MONITOR FOR A POSSIBLE NORTHWARD ADJUSTMENT IN THE TRACK AND BETTER FORCING. WHERE GOOD SYNOPTIC FORCING LACKS ACROSS THE THUMB REGION...SOME ADDITIONAL SNOWFALL MAY COME FROM LAKE EFFECT ENHANCEMENT. THE ONLY AREA THAT MAY STRUGGLE TO SEE MUCH SYNOPTIC ACCUMULATION WILL BE IN THE SAGINAW VALLEY...AND WILL SCALE BACK QPF/SNOW AMOUNTS SLIGHTLY HERE. 12Z MODEL SUITE REMAIN IN STRONG AGREEMENT AND CARRY GOOD RUN TO RUN CONTINUITY WITH THE PATTERN EVOLUTION BY MIDWEEK. THE WEAKER SYSTEM LIFTING THROUGH MONDAY WILL LEAD IN A STRONGER SHORTWAVE FOR TUESDAY...WITH THIS ENERGY CARVING OUT A DEEPER LONGWAVE TROUGH AND ALLOWING A BRIEF SHOT OF ARCTIC AIR TO SPILL IN FOR TUESDAY NIGHT/ WEDNESDAY. STRENGTHENING COLD AIR ADVECTION ON TUESDAY WITH 850 MB TEMPERATURES DROPPING BELOW -10C WILL CREATE MARGINALLY FAVORABLE CONDITIONS FOR LAKE ENHANCED SNOW SHOWERS DURING THE DAY. THE LATEST GFS INDICATING A NARROW CONVERGENCE ZONE DEVELOPING ACROSS THE EASTERN PORTION OF THE THUMB...WITH A SMALL WINDOW OF PREDOMINANT NORTH-NORTHEAST FLOW OVER LAKE HURON INCREASING THE POTENTIAL FOR HIGHER SNOW AMOUNTS IN THESE LOCATIONS LATE TUESDAY. MORE ORGANIZED ACTIVITY WILL DEVELOP BY TUESDAY EVENING AREAWIDE AS FORCING/CONVERGENCE INCREASES ALONG THE ARCTIC FRONTAL BOUNDARY DROPPING SOUTH ACROSS SOUTHERN MI...AND LIKELY POPS REMAIN APPROPRIATE FOR THIS PERIOD. OVERALL...ADDITIONAL ACCUMULATIONS UP TO 2 INCHES (HIGHEST NORTH) STILL SEEMS REASONABLE AREAWIDE...WITH LOCALLY HIGHER AMOUNTS POSSIBLE ESPECIALLY IN THE FAVORED LAKE ENHANCED AREAS ACROSS THE THUMB. ARCTIC AIRMASS WILL SETTLE OVERHEAD BRIEFLY FOR WEDNESDAY...WITH LINGERING SCATTERED SNOW SHOWERS. BASED ON PROJECTED 850 MB/ THICKNESS TRENDS...TEMPERATURES WILL LIKELY HOLD STEADY OR SLOWLY FALL...AND NOT REACH MUCH ABOVE THE LOWER 20S. AT LEAST PARTIAL CLEARING WEDNESDAY NIGHT...COMBINED WITH A WEAKENING GRADIENT WITH HIGH PRESSURE BUILDING ACROSS THE OHIO VALLEY...WILL BRING THE COLDEST NIGHT OF THE FORECAST PERIOD. GOING FORECAST WITH LOWS BOTTOMING OUT IN THE 5-10F RANGE STILL LOOKING GOOD FOR THURSDAY MORNING. BIG PATTERN CHANGE FOR THE LATTER HALF OF THE FORECAST PERIOD...AS MODEL CONSENSUS PLACES THE GREAT LAKES WITHIN AN INCREASINGLY DEEP SOUTHWEST FLOW...BETWEEN STRENGTHENING RIDGING ACROSS THE EAST COAST AND A LONGWAVE TROUGH OVER THE WESTERN THIRD OF THE CONUS. THIS WILL LEAD TO A PRONOUNCED WARMUP BY THE WEEKEND...WITH 850 MB TEMPS CLIMBING INTO THE 5-10C RANGE BY SUNDAY. IT WILL TAKE SOME TIME TO SCOUR OUT THE ARCTIC AIR INITIALLY...AND WILL CONTINUE TO TEMPER THE WARMUP ON THURSDAY...AS THE COLD MORNING START AND SNOW COVER POTENTIAL WILL CERTAINLY COUNTER ANY INCREASE IN WARM AIR ADVECTION/ RISING THICKNESSES. HOWEVER...BY THE WEEKEND EXPECT TEMPERATURES TO CLIMB WELL ABOVE NORMAL...WITH HIGHS ON SUNDAY POTENTIALLY APPROACHING 50F ACROSS THE SOUTH. INCREASING ISENTROPIC ACCENT AND THE PASSAGE OF A WEAK SHORTWAVE WILL BRING THE NEXT CHANCE OF PCPN BY SATURDAY...WITH THE THERMAL PROFILES LOOKING MORE LIKE ALL RAIN. && .MARINE... AN AREA OF LOW PRESSURE WILL BECOME ORGANIZED OVER THE UPPER MIDWEST TONIGHT. THIS SYSTEM WILL DEEPEN AS IT MOVES ACROSS THE SOUTHERN GREAT LAKES MONDAY NIGHT...AND CONTINUE TO INTENSIFY THROUGH TUESDAY AS IT TRACKS INTO NEW ENGLAND. MEANWHILE...A VERY LARGE AND STRONG AREA OF HIGH PRESSURE WILL BUILD IN ITS WAKE TUESDAY OVER THE CENTRAL PLAINS. WITH OUR AREA IN THE CENTER OF THESE TWO STRENGTHENING SYSTEMS...A PROLONGED PERIOD OF GUSTY WINDS WILL OCCUR OVER ALL MARINE AREAS TUESDAY MORNING THROUGH WEDNESDAY EVENING. WINDS ARE EXPECTED TO REMAIN BELOW GALE STRENGTH...BUT SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED. && .PREV DISCUSSION...ISSUED 1249 PM EST SUN DEC 30 2007 AVIATION... SOME HOLES HAVE BEGUN TO APPEAR IN THE STRATUS DECK THIS AFTERNOON...MAINLY OVER THE CENTRAL AND WESTERN PORTIONS OF LOWER MICHIGAN. FNT AND MBS WILL CONTINUE TO LIFT INTO VFR CONDITIONS AND REMAIN THERE UNTIL THE NEXT SYSTEM AFFECTS THE REGION TONIGHT. ABUNDANCE OF HIGH AND MID LEVEL CLOUDS MOVING OVER THE DETROIT AREA WILL KEEP THE STRATUS DECK INTACT OVER DTW AND DET THIS AFTERNOON...AND WILL CONTINUE THE FORECAST FOR MVFR CEILINGS THERE UNTIL THIS EVENING WHEN CONDITIONS WILL WORSEN. A WEAK AREA OF LOW PRESSURE WILL FORM OVER PENNSYLVANIA THIS EVENING. SNOW WRAPPING AROUND THE NORTH END OF THIS SYSTEM WILL MOVE INTO LOWER MICHIGAN...PRIMARILY AFTER 00Z. WILL THEN SEE ABOUT A 4 TO 6 HOUR PERIOD OF LIGHT SNOW THAT WILL PRIMARILY IMPACT DTW AND DET. CEILINGS AND VISIBILITIES THERE WILL DROP INTO IFR TONIGHT AS THIS AREA OF SNOWFALL MOVES THROUGH. ACCUMULATIONS WILL BE UNDER AN INCH. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...HLO LONG TERM....MR MARINE.......HLO AVIATION.....HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1245 PM EST SUN DEC 30 2007 .SYNOPSIS... WV AND 500MB RUC ANALYSIS SHOW A LONGWAVE TROUGH SPREAD ACROSS THE CONUS. THERE IS A STRONG SHORTWAVE AT THE BASE OF THE TROUGH SITUATED ON THE OK/TX BORDER...AND ANOTHER SHORTWAVE OVER WASHINGTON. THE OK/TX SHORTWAVE WILL DIG ITS WAY INTO THE OHIO RIVER VALLEY TODAY AND TONIGHT AND NOT REALLY IMPACT OUR CWA. THE WA SHORTWAVE WILL DIG AN AMPLIFIED TROUGH THROUGH THE CENTRAL CONUS ON MONDAY AND PLAY A PART IN OUR WEATHER ON TUE. MEANWHILE...A VORTEX OVER NORTH CENTRAL CANADA IS PROGGED TO DIP DOWN INTO MN AROUND 12Z TUE. THIS STRONG 500MB SHORTWAVE WILL INTERACT WITH THE WA TROUGH AND SFC LOW PRES WILL STRENGTHEN OVER THE LOWER GREAT LAKES AREA TUE MORNING. BEHIND THE SFC LOW...ARCTIC AIR WILL FILTER DOWN ACROSS LAKE SUPERIOR AND KICK UP SOME FAIRLY SIGNIFICANT LAKE ENHANCED AND LAKE EFFECT SNOW TUE AND TUE NIGHT. LES WILL CONTINUE THROUGH WED NIGHT UNTIL SOUTHERLY FLOW RESUMES ON THU. && .DISCUSSION... TODAY...LIGHT SNOW/FLURRIES ARE SPREAD ACROSS UPPER MI AND NORTH CENTRAL WI AS WAA AND WEAK ISENTROPIC LIFT FILTER INTO THE AREA. A VERY WEAK SHORTWAVE OVER THE REGION IS ALSO APPARENT IN WV IMAGERY. KEPT ISOLATED SNOW SHOWERS GOING FOR MOST OF THE CWA THROUGH EARLY AFTERNOON. A WEAK CONVERGENCE ZONE SITUATED OVER LAKE SUPERIOR WILL KEEP SNOW SHOWERS GOING THROUGH THE AFTERNOON...SLOWLY LIFTING NORTHWARD AND AWAY FROM THE KEWEENAW. TONIGHT AND MONDAY...WAA AND WEAK ISENTROPIC LIFT MAY CONTRIBUTE TO SOME LIGHT SNOW OVERNIGHT...MAINLY OVER THE FAR EASTERN U.P. (LAKE ENHANCEMENT OFF OF LAKE MICHIGAN WITH THE SOUTHERLY FLOW). THERE IS MOISTURE AVAILABLE...BUT BETTER FORCING AND MORE MOISTURE ENTER THE PICTURE AFTER MIDNIGHT. FOR NOW...KEPT CHANCE POPS FOR THE WHOLE NIGHT...BUT MAY BE ABLE TO INCREASE POPS FOR AFTER 06Z DURING NEXT FORECAST UPDATE. MONDAY...SIMILAR FORCING CONTINUES. RAISED POPS SLIGHTLY IN THE AFTERNOON TO ACCOUNT FOR DEEPER MOISTURE. STILL HAVE LITTLE CONFIDENCE IN COVERAGE OF THIS PCPN. MONDAY NIGHT THROUGH WEDNESDAY...LAKE ENHANCED SNOW WILL BEGIN ACROSS THE WESTERN U.P. AS THE WINDS CHANGE TO NW OVERNIGHT. WENT WITH 20:1 SNOW RATIO FOR MON NIGHT...THEN INCREASED THE RATIO TO 25:1 FOR TUE...AND INCREASED IT EVEN MORE TO 30:1 FOR TUE NIGHT AND WED. AS TWO UPPER LEVEL SHORTWAVES CROSS OVER LAKE SUPERIOR MON NIGHT THROUGH TUE...SNOWFALL MAY TOTAL UP TO WARNING CRITERIA IN SOME LAKE SUPERIOR SHORELINE AREAS. DID NOT MAKE ANY CHANGES TO GOING QPF/SNOWFALL FIELDS. DECREASED LOW TEMPS TUE NIGHT...HIGH TEMPS WED...AND LOW TEMPS WED NIGHT A TINY BIT. DECREASED DEW POINT TEMPS TUE NIGHT...AS WELL. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... SATELLITE LOOPS SUGGESTS THAT AREAS OF MAINLY CLEAR SKIES OVER WEST AND CENTRAL UPPER MI MAY FILL BACK IN WITH DIUNRAL CLOUD DEVELOPMENT AND ADVECTION OF MOISTURE FROM THE SOUTH WHERE MORE PROMINENT STRATUS WAS OBSERVED. BY TONIGHT MVFR CONDITIONS ARE EXPECTED THAT SHOULD PERSIST INTO MON MORNING AS A STRONG 3K-4K FT INVERSION PERSISTS OVER THE REGION. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEAK HIGH PRESSURE OVER THE AREA SHOULD KEEP WINDS BLO 25 KNOTS INTO MONDAY. A LOW PRESSURE SYSTEM TAKING SHAPE IN THE NORTHERN PLAINS WILL THEN MOVE INTO THE UPPER GREAT LAKES ON MONDAY. A TIGHT NRLY GRADIENT WILL DEVELOP ON THE BACKSIDE OF THE LOW ON MON NIGHT INTO TUE AS STRONG HIGH PRESSURE BUILDS INTO THE PLAINS. KEPT GOING FCST OF WINDS TO 30 KT ALTHOUGH GALE FORCE GUSTS ARE CERTAINLY POSSIBLE AS COLD ADVECTION/MIXING ALLOWS HIGHER WIND GUSTS TO REACH THE SURFACE OF THE LAKE. LOOK FOR WINDS TO DIMINISH TO BLO 25 KTS BY WED EVENING AS THE HIGH PRES RIDGE FROM THE PLAINS MOVES OVER THE REGION. GALES ARE POSSIBLE THU AFTERNOON AND EVENING AS A LOW-LEVEL JET CORE DEVELOPS OVER THE REGION AHEAD OF ANOTHER NORTHERN PLAINS TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...MRC AVIATION...JLB MARINE...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1200 AM EST SUN DEC 30 2007 .AVIATION... A RIDGE OF SURFACE HIGH PRESSURE FROM CENTRAL WISCONSIN INTO SOUTHERN OHIO IS MOVING SLOWLY TO THE NORTHEAST EARLY THIS MORNING, AND HELPING TO SCOUR AWAY THE STRATUS IN ITS WAKE. THIS IS CORRELATED NICELY ON SATELLITE AND SURFACE OBSERVATIONS WITH THE EDGE OF THE STRATUS LINED UP ROUGHLY ALONG THE RIDGE AXIS. THE CLEARING LINE WILL MAKE IT TO THE DETROIT AREA AROUND SUNRISE BUT THE PLAN IS TO DELAY THE TIMING AT FLINT AND TRI CITES UNTIL LATER IN THE MORNING OR CLOSER TO NOON AS THE RIDGE AXIS REORIENTS ITSELF MORE SOUTHWEST TO NORTHEAST. A SHORT BREAK OF VFR CONDITIONS IS THEN EXPECTED AT DETROIT BEFORE MOISTURE ARRIVES FROM THE SOUTH AGAIN BY EVENING. SOME LIGHT SNOW WILL BE POSSIBLE DURING THE EVENING HOURS AND TAKE CONDITIONS BACK DOWN TO MVFR. && .PREV DISCUSSION...ISSUED 314 PM EST SAT DEC 29 2007 SHORT TERM...THROUGH TONIGHT SURFACE HIGH PRESSURE WILL BUILD OVER THE OHIO VALLEY TONIGHT AND EXTEND UP INTO THE SOUTHERN GREAT LAKES. THIS WILL BRING DRY WEATHER AND ALLOW WINDS TO RELAX. MAIN FORECAST CHALLENGE FOR THE SHORT TERM REMAINS CENTERED AROUND THE POSSIBLE BREAK-UP OF THE STRATUS DECK ENTRENCHED OVER THE REGION. WESTERLY FLOW OFF LAKE MICHIGAN HAS HELPED KEEP THIS DECK INTACT THIS AFTERNOON. 12Z DTX SOUNDING INDICATES THE MIXED LAYER TO BE POTENTIALLY 5000 FEET DEEP...BUT FORECAST SOUNDINGS SHOW THIS LAYER SHRINKING THROUGH THE AFTERNOON AS INVERSION HEIGHTS LOWER. FORECAST SOUNDINGS ALSO SHOW THE AIRMASS REMAINING FAIRLY SATURATED IN THE LOWER LEVELS THROUGH MUCH OF THE AFTERNOON...BEFORE SOME DRIER AIR IS MIXED DOWN DURING THE LATE AFTERNOON. MODELS LOOK TOO AGGRESSIVE WITH THIS MIXING AS THEY ARE TOO WARM WITH SURFACE TEMPERATURES AND AT LEAST 1000 FEET TOO LOW WITH THE INVERSION HEIGHTS (WHERE DRIER AIR RESIDES ABOVE). THINK THE LOWER LAYERS WILL STAY A LITTLE MORE MOIST THAN INDICATED...FAVORING A MORE INTACT DECK. WATER VAPOR IMAGERY SHOWS A SMALL UPPER SHORTWAVE TRACKING UP THROUGH ILLINOIS AND INDIANA. NAM AND RUC MODELS HAVE THE BEST HANDLE ON THIS FEATURE...BUT LARGELY SHEAR IT OUT BEFORE IT REACHES THE EASTERN PORTION OF THE MICHIGAN/OHIO BORDER BY 00Z. UPSTREAM OVER ILLINOIS...THIS FEATURE HAS HELPED CLEAR OUT MOST OF THE STRATUS. HOWEVER...NOT SURE IT WILL BE STRONG ENOUGH TO BREAK UP THE DECK OVER THE SOUTHERN FORECAST AREA. TAKING INTO ACCOUNT ALL THIS INFORMATION...WILL KEEP THE DECK LARGELY INTACT FOR THE AFTERNOON FORECAST PACKAGE. EXPECTING A FEW BREAKS TO APPEAR DURING THE LATE AFTERNOON/EARLY EVENING HOWEVER. CIRRUS SHIELD WILL EXPAND OVERNIGHT FROM THE SOUTHERN PLAINS TO THE OHIO VALLEY AS THE BROAD UPPER TROUGH CROSSING THE ROCKIES BECOMES MORE AMPLIFIED. HIGH CLOUDS WILL START TO SPREAD INTO THE SOUTHERN HALF OF THE FORECAST AREA DURING THE EARLY MORNING...THROUGH THEY WILL ARRIVE TOO LATE TO HAVE A BIG IMPACT ON TEMPERATURES. OVERNIGHT LOWS WILL RUN 8 TO 10 DEGREES BELOW LAST NIGHT`S MILD READINGS...BOTTOMING OUT IN THE LOW TO MID 20S. LONG TERM... HIGH PRESSURE SLIDES EAST ON SUNDAY...AS A SHORTWAVE DIGS INTO THE TENNESSEE VALLEY AND INDUCES COASTAL ATLANTIC CYCLOGENESIS. TEMPERATURES ON SUNDAY WILL REBOUND SLIGHTLY FROM TODAY...AS THE GRADIENT TAKES ON MORE OF A SOUTHERLY COMPONENT AND THINNER HIGH/MID CLOUDS CONTROL THE SKY CONDITION. BOTH THE NAM AND GFS HINT AT SECONDARY WEAK SFC LOW DEVELOPMENT WEST OF THE APPALACHIANS... ALLOWING FOR A NARROW AREA OF LGT PCPN TO DEVELOP ALONG THE DEFORMATION AXIS LIFTING NORTHEAST FROM SOUTHWEST OHIO THROUGH LAKE ERIE SUNDAY EVENING. THE VERY NORTHWEST EDGE OF THIS MAY CLIP EXTREME SOUTHEAST LOWER MI...AND WILL JUST INTRODUCE A SLIGHT CHANCE POP THROUGH 06Z FROM MONROE TO MACOMB COUNTY FOR VERY LGT SNOW SHOWERS WITH NO ACCUMS EXPECTED. OTHERWISE...WILL BACK OFF ON POPS FOR THE OVERNIGHT PERIOD...AS MODEL CONSENSUS REMAINS SUFFICIENT THAT IMPACTS FROM THE NEXT APPROACHING SYSTEM WILL HOLD UNTIL MONDAY. THIS SYSTEM BECOMES THE MAIN FOCUS FOR THIS FORECAST PACKAGE... LIKELY IMPACTING MUCH OF SOUTHEAST LOWER MICHIGAN LATE ON NEW YEARS EVE. SHORTWAVE MOVING ONSHORE ACROSS BRITISH COLUMBIA LATE TONIGHT...WILL DROP SOUTHEAST WITHIN THE MEAN CENTRAL U.S. TROUGH... STRENGTHENING SLIGHTLY AND INDUCING SFC LOW DEVELOPMENT AS IT MOVES INTO THE NORTHERN PLAINS/GREAT LAKES THROUGH EARLY MONDAY. IN RESPONSE TO THE DIFFICULTY IN RESOLVING SUCH A LOW AMPLITUDE WAVE BEFORE IT CAN BE PROPERLY SAMPLED...THE MODELS CONTINUE TO STRUGGLE WITH THE FINER DETAILS WITH THIS SYSTEM...WITH THE BIGGEST STRUGGLES INVOLVING WHERE TO PLACE THE BEST FORCING AND ASSOCIATED MAIN MOISTURE AXIS. ALL MODELS AGREE ON TAKING THE SFC LOW FROM WEST TO EAST ACROSS NORTHERN/CENTRAL LOWER MI. HOWEVER...THE NAM (WITH SUPPORT FROM SREF OUTPUT) MAINTAINS A MUCH MORE COMPACT SYSTEM...AND FOCUSES THE BULK OF THE PCPN FROM THE SAGINAW VALLEY NORTHWARD. MEANWHILE...THE GFS INDICATES A MUCH BROADER SYSTEM...WITH A HIGHER AXIS OF QPF (.1-.2") SOUTH OF THE SFC LOW FOCUSED ALONG THE FRONTAL CONVERGENCE ZONE AND WITHIN AN AREA OF ENHANCED FORCING PROVIDED BY THE SHORTWAVE. THE ECMWF SHOWS A SIMILAR DEPICTION...ONLY WITH MUCH LESS QPF IN A SHORTER DURATION. GIVEN THE POOR CONSENSUS...WILL GENERALLY TAKE A BLEND...ADJUSTING PCPN AMOUNTS UP SLIGHTLY ACROSS THE SOUTH BUT UNDERCUTTING THE HIGHER AMOUNTS SHOWN BY THE GFS. THIS WILL MAKE SNOW ACCUMULATIONS FROM A DUSTING TO 2 INCHES POSSIBLE AREAWIDE MONDAY AFTERNOON/EVENING...WITH THE POTENTIAL FOR NARROW CORRIDOR OF HIGHER END AMOUNTS UP TO 3 INCHES SOMEWHERE WITHIN THE CWA. DECENT MODEL AGREEMENT EXISTS WITH REGARD TO THE PATTERN EVOLUTION FOR MID-WEEK...WITH A DEEPENING LONGWAVE TROUGH LIFTING FROM THE CENTRAL TO EASTERN CONUS...WHILE RIDGING BUILDS ACROSS THE WEST. THIS AMPLIFIED FLOW WILL LIKELY BRING THE COLDEST AIRMASS OF THE SEASON SOUTHWARD INTO THE GREAT LAKES...AS COLD AIR ADVECTION DEVELOPS TUESDAY BEHIND THE DEPARTING NEW YEARS EVE SYSTEM...WITH A REINFORCING ARCTIC COLD FRONT ARRIVING BY TUESDAY NIGHT. GREAT LAKES REGION WILL LIKELY SEE JUST A GLANCING BLOW WITH THIS ARCTIC SURGE WITH THE BETTER DROP IN 850 MB TEMPS/THICKNESSES OCCURRING ACROSS THE PLAINS/MIDWEST...WITH SOME AIRMASS MODIFICATION BY THE UPSTREAM LAKES LIKELY UPON ARRIVAL TUES NGT/WEDNESDAY. NONETHELESS...HIGHS ONLY IN THE LOW/MID 20S UNDER A GUSTY NORTHWEST GRADIENT STILL LOOKS REASONABLE ON WEDNESDAY GIVEN THE PROJECTED 850MB TEMPS. A WEAKENING LOW LEVEL WIND FIELD AND PARTIAL CLEARING WILL BRING SOME ENHANCED RADIATIONAL COOLING POTENTIAL WED NGT...AND WILL REMAIN BELOW GUIDANCE WITH MANY LOCATIONS (OUTSIDE OF THE DETROIT URBAN HEAT ISLAND) SEEING LOWS IN THE 8-12F RANGE THURSDAY MORNING. THE STRONG COLD AIR ADVECTION WITH INCREASINGLY FAVORABLE 850 MB TEMPS/LAPSE RATES...ENHANCED VORTICITY WITHIN THE BROAD CYCLONIC FLOW...AND ADDED LOW LEVEL CONVERGENCE PROVIDED BY THE ARCTIC FRONT...WILL PROMOTE SCATTERED TO NUMEROUS SNOW SHOWER ACTIVITY TUESDAY AND TUESDAY NIGHT. MODELS REALLY KEYING ON THE ARCTIC BOUNDARY FOR MORE ORGANIZED DEVELOPMENT FROM 18-03Z LATE TUESDAY...WITH POTENTIAL SNOW ACCUMS OF 1-2 INCHES (HIGHEST NORTH). MODELS INSISTING ON A QUICK RECOVERY OF THE AIRMASS BACK TOWARD MORE SEASONABLE TEMPERATURE READINGS BY THURSDAY AND FRIDAY...WITH PRONOUNCED WARM AIR ADVECTION/RISING THICKNESSES DEVELOPING ON THE BACKSIDE OF A DEPARTING SFC HIGH. WHILE THE GFS/ECMWF/CANADIAN AND ENSEMBLES ALL AGREE ON THIS...WILL CONTINUE TO TEMPER THE WARMUP SLIGHTLY THURSDAY THE COLD MORNING START AND THE TYPICAL MODEL BIAS FOR SCOURING OUT AN ARCTIC AIRMASS TOO QUICKLY. ALSO...THE UPSTREAM UPPER RIDGE LOOKS TO DAMPEN AS IT ARRIVES...THUS LESSENING THE OVERALL DEPTH/STRENGTH OF THE SOUTHWEST RETURN FLOW. TEMPERATURES WILL RETURN TO MORE SEASONABLE READINGS BY FRIDAY. MARINE... WINDS WILL CONTINUE TO DIMINISH ACROSS THE MICHIGAN NEARSHORE WATERS THROUGH THE EVENING AND OVERNIGHT AS LOW PRESSURE OVER QUEBEC CONTINUES TO MOVE NORTHEAST AND HIGH PRESSURE BUILDS OVER THE SOUTHERN GREAT LAKES. A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE GREAT LAKES MONDAY AND MONDAY NIGHT. STRONG COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM WILL HAVE TO POTENTIAL TO PRODUCE GALE FORCE WIND GUSTS OVER MUCH OF LAKE HURON FROM EARLY TUESDAY MORNING THROUGH WEDNESDAY MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... GALE WATCH...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 4 AM TUESDAY TO 7 AM WEDNESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT SHORT TERM...HLO LONG TERM....MR MARINE.......HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 648 PM EST SAT DEC 29 2007 .AVIATION... STRATUS REMAINS FIRMLY ENTRENCHED ALONG AND NORTH OF THE SURFACE HIGH PRESSURE RIDGE, AND OVER SE MICHIGAN, THIS EVENING. SATELLITE IMAGERY DOES SHOW THE EDGE MAKING PROGRESS TO THE NORTHEAST THROUGH ILLINOIS, A TREND WHICH IS EXPECTED TO CONTINUE INTO THE EARLY MORNING HOURS. GIVEN THE TRAPPED NATURE OF THE MOISTURE IN THE BOUNDARY LAYER, AS IS USUALLY THE CASE, IT WILL REQUIRE AN AIR MASS CHANGE TO CLEAR OUT THE SKY OVER OUR AREA. THIS WILL OCCUR AS THE SURFACE RIDGE BUILDS TOWARD THE NORTH AND EAST AND LOW LEVEL FLOW TURNS MORE TOWARD THE SOUTH. THE CHANGE IN WIND DIRECTION, ALONG WITH THE RELATIVE POSITION OF THE SURFACE RIDGE, WILL SERVE AS A GOOD TRACER FOR THE CLEARING TREND IN THE STRATUS LATE IN THE OVERNIGHT AND EARLY SUNDAY MORNING. MVFR CEILING WILL THEN BECOME VFR AS THE LOW CLOUDS ARE REPLACED BY THICK CIRRUS DURING SUNDAY AFTERNOON. && .PREV DISCUSSION...ISSUED 314 PM EST SAT DEC 29 2007 SHORT TERM...THROUGH TONIGHT SURFACE HIGH PRESSURE WILL BUILD OVER THE OHIO VALLEY TONIGHT AND EXTEND UP INTO THE SOUTHERN GREAT LAKES. THIS WILL BRING DRY WEATHER AND ALLOW WINDS TO RELAX. MAIN FORECAST CHALLENGE FOR THE SHORT TERM REMAINS CENTERED AROUND THE POSSIBLE BREAK-UP OF THE STRATUS DECK ENTRENCHED OVER THE REGION. WESTERLY FLOW OFF LAKE MICHIGAN HAS HELPED KEEP THIS DECK INTACT THIS AFTERNOON. 12Z DTX SOUNDING INDICATES THE MIXED LAYER TO BE POTENTIALLY 5000 FEET DEEP...BUT FORECAST SOUNDINGS SHOW THIS LAYER SHRINKING THROUGH THE AFTERNOON AS INVERSION HEIGHTS LOWER. FORECAST SOUNDINGS ALSO SHOW THE AIRMASS REMAINING FAIRLY SATURATED IN THE LOWER LEVELS THROUGH MUCH OF THE AFTERNOON...BEFORE SOME DRIER AIR IS MIXED DOWN DURING THE LATE AFTERNOON. MODELS LOOK TOO AGGRESSIVE WITH THIS MIXING AS THEY ARE TOO WARM WITH SURFACE TEMPERATURES AND AT LEAST 1000 FEET TOO LOW WITH THE INVERSION HEIGHTS (WHERE DRIER AIR RESIDES ABOVE). THINK THE LOWER LAYERS WILL STAY A LITTLE MORE MOIST THAN INDICATED...FAVORING A MORE INTACT DECK. WATER VAPOR IMAGERY SHOWS A SMALL UPPER SHORTWAVE TRACKING UP THROUGH ILLINOIS AND INDIANA. NAM AND RUC MODELS HAVE THE BEST HANDLE ON THIS FEATURE...BUT LARGELY SHEAR IT OUT BEFORE IT REACHES THE EASTERN PORTION OF THE MICHIGAN/OHIO BORDER BY 00Z. UPSTREAM OVER ILLINOIS...THIS FEATURE HAS HELPED CLEAR OUT MOST OF THE STRATUS. HOWEVER...NOT SURE IT WILL BE STRONG ENOUGH TO BREAK UP THE DECK OVER THE SOUTHERN FORECAST AREA. TAKING INTO ACCOUNT ALL THIS INFORMATION...WILL KEEP THE DECK LARGELY INTACT FOR THE AFTERNOON FORECAST PACKAGE. EXPECTING A FEW BREAKS TO APPEAR DURING THE LATE AFTERNOON/EARLY EVENING HOWEVER. CIRRUS SHIELD WILL EXPAND OVERNIGHT FROM THE SOUTHERN PLAINS TO THE OHIO VALLEY AS THE BROAD UPPER TROUGH CROSSING THE ROCKIES BECOMES MORE AMPLIFIED. HIGH CLOUDS WILL START TO SPREAD INTO THE SOUTHERN HALF OF THE FORECAST AREA DURING THE EARLY MORNING...THROUGH THEY WILL ARRIVE TOO LATE TO HAVE A BIG IMPACT ON TEMPERATURES. OVERNIGHT LOWS WILL RUN 8 TO 10 DEGREES BELOW LAST NIGHT`S MILD READINGS...BOTTOMING OUT IN THE LOW TO MID 20S. LONG TERM... HIGH PRESSURE SLIDES EAST ON SUNDAY...AS A SHORTWAVE DIGS INTO THE TENNESSEE VALLEY AND INDUCES COASTAL ATLANTIC CYCLOGENESIS. TEMPERATURES ON SUNDAY WILL REBOUND SLIGHTLY FROM TODAY...AS THE GRADIENT TAKES ON MORE OF A SOUTHERLY COMPONENT AND THINNER HIGH/MID CLOUDS CONTROL THE SKY CONDITION. BOTH THE NAM AND GFS HINT AT SECONDARY WEAK SFC LOW DEVELOPMENT WEST OF THE APPALACHIANS... ALLOWING FOR A NARROW AREA OF LGT PCPN TO DEVELOP ALONG THE DEFORMATION AXIS LIFTING NORTHEAST FROM SOUTHWEST OHIO THROUGH LAKE ERIE SUNDAY EVENING. THE VERY NORTHWEST EDGE OF THIS MAY CLIP EXTREME SOUTHEAST LOWER MI...AND WILL JUST INTRODUCE A SLIGHT CHANCE POP THROUGH 06Z FROM MONROE TO MACOMB COUNTY FOR VERY LGT SNOW SHOWERS WITH NO ACCUMS EXPECTED. OTHERWISE...WILL BACK OFF ON POPS FOR THE OVERNIGHT PERIOD...AS MODEL CONSENSUS REMAINS SUFFICIENT THAT IMPACTS FROM THE NEXT APPROACHING SYSTEM WILL HOLD UNTIL MONDAY. THIS SYSTEM BECOMES THE MAIN FOCUS FOR THIS FORECAST PACKAGE... LIKELY IMPACTING MUCH OF SOUTHEAST LOWER MICHIGAN LATE ON NEW YEARS EVE. SHORTWAVE MOVING ONSHORE ACROSS BRITISH COLUMBIA LATE TONIGHT...WILL DROP SOUTHEAST WITHIN THE MEAN CENTRAL U.S. TROUGH... STRENGTHENING SLIGHTLY AND INDUCING SFC LOW DEVELOPMENT AS IT MOVES INTO THE NORTHERN PLAINS/GREAT LAKES THROUGH EARLY MONDAY. IN RESPONSE TO THE DIFFICULTY IN RESOLVING SUCH A LOW AMPLITUDE WAVE BEFORE IT CAN BE PROPERLY SAMPLED...THE MODELS CONTINUE TO STRUGGLE WITH THE FINER DETAILS WITH THIS SYSTEM...WITH THE BIGGEST STRUGGLES INVOLVING WHERE TO PLACE THE BEST FORCING AND ASSOCIATED MAIN MOISTURE AXIS. ALL MODELS AGREE ON TAKING THE SFC LOW FROM WEST TO EAST ACROSS NORTHERN/CENTRAL LOWER MI. HOWEVER...THE NAM (WITH SUPPORT FROM SREF OUTPUT) MAINTAINS A MUCH MORE COMPACT SYSTEM...AND FOCUSES THE BULK OF THE PCPN FROM THE SAGINAW VALLEY NORTHWARD. MEANWHILE...THE GFS INDICATES A MUCH BROADER SYSTEM...WITH A HIGHER AXIS OF QPF (.1-.2") SOUTH OF THE SFC LOW FOCUSED ALONG THE FRONTAL CONVERGENCE ZONE AND WITHIN AN AREA OF ENHANCED FORCING PROVIDED BY THE SHORTWAVE. THE ECMWF SHOWS A SIMILAR DEPICTION...ONLY WITH MUCH LESS QPF IN A SHORTER DURATION. GIVEN THE POOR CONSENSUS...WILL GENERALLY TAKE A BLEND...ADJUSTING PCPN AMOUNTS UP SLIGHTLY ACROSS THE SOUTH BUT UNDERCUTTING THE HIGHER AMOUNTS SHOWN BY THE GFS. THIS WILL MAKE SNOW ACCUMULATIONS FROM A DUSTING TO 2 INCHES POSSIBLE AREAWIDE MONDAY AFTERNOON/EVENING...WITH THE POTENTIAL FOR NARROW CORRIDOR OF HIGHER END AMOUNTS UP TO 3 INCHES SOMEWHERE WITHIN THE CWA. DECENT MODEL AGREEMENT EXISTS WITH REGARD TO THE PATTERN EVOLUTION FOR MID-WEEK...WITH A DEEPENING LONGWAVE TROUGH LIFTING FROM THE CENTRAL TO EASTERN CONUS...WHILE RIDGING BUILDS ACROSS THE WEST. THIS AMPLIFIED FLOW WILL LIKELY BRING THE COLDEST AIRMASS OF THE SEASON SOUTHWARD INTO THE GREAT LAKES...AS COLD AIR ADVECTION DEVELOPS TUESDAY BEHIND THE DEPARTING NEW YEARS EVE SYSTEM...WITH A REINFORCING ARCTIC COLD FRONT ARRIVING BY TUESDAY NIGHT. GREAT LAKES REGION WILL LIKELY SEE JUST A GLANCING BLOW WITH THIS ARCTIC SURGE WITH THE BETTER DROP IN 850 MB TEMPS/THICKNESSES OCCURRING ACROSS THE PLAINS/MIDWEST...WITH SOME AIRMASS MODIFICATION BY THE UPSTREAM LAKES LIKELY UPON ARRIVAL TUES NGT/WEDNESDAY. NONETHELESS...HIGHS ONLY IN THE LOW/MID 20S UNDER A GUSTY NORTHWEST GRADIENT STILL LOOKS REASONABLE ON WEDNESDAY GIVEN THE PROJECTED 850MB TEMPS. A WEAKENING LOW LEVEL WIND FIELD AND PARTIAL CLEARING WILL BRING SOME ENHANCED RADIATIONAL COOLING POTENTIAL WED NGT...AND WILL REMAIN BELOW GUIDANCE WITH MANY LOCATIONS (OUTSIDE OF THE DETROIT URBAN HEAT ISLAND) SEEING LOWS IN THE 8-12F RANGE THURSDAY MORNING. THE STRONG COLD AIR ADVECTION WITH INCREASINGLY FAVORABLE 850 MB TEMPS/LAPSE RATES...ENHANCED VORTICITY WITHIN THE BROAD CYCLONIC FLOW...AND ADDED LOW LEVEL CONVERGENCE PROVIDED BY THE ARCTIC FRONT...WILL PROMOTE SCATTERED TO NUMEROUS SNOW SHOWER ACTIVITY TUESDAY AND TUESDAY NIGHT. MODELS REALLY KEYING ON THE ARCTIC BOUNDARY FOR MORE ORGANIZED DEVELOPMENT FROM 18-03Z LATE TUESDAY...WITH POTENTIAL SNOW ACCUMS OF 1-2 INCHES (HIGHEST NORTH). MODELS INSISTING ON A QUICK RECOVERY OF THE AIRMASS BACK TOWARD MORE SEASONABLE TEMPERATURE READINGS BY THURSDAY AND FRIDAY...WITH PRONOUNCED WARM AIR ADVECTION/RISING THICKNESSES DEVELOPING ON THE BACKSIDE OF A DEPARTING SFC HIGH. WHILE THE GFS/ECMWF/CANADIAN AND ENSEMBLES ALL AGREE ON THIS...WILL CONTINUE TO TEMPER THE WARMUP SLIGHTLY THURSDAY THE COLD MORNING START AND THE TYPICAL MODEL BIAS FOR SCOURING OUT AN ARCTIC AIRMASS TOO QUICKLY. ALSO...THE UPSTREAM UPPER RIDGE LOOKS TO DAMPEN AS IT ARRIVES...THUS LESSENING THE OVERALL DEPTH/STRENGTH OF THE SOUTHWEST RETURN FLOW. TEMPERATURES WILL RETURN TO MORE SEASONABLE READINGS BY FRIDAY. MARINE... WINDS WILL CONTINUE TO DIMINISH ACROSS THE MICHIGAN NEARSHORE WATERS THROUGH THE EVENING AND OVERNIGHT AS LOW PRESSURE OVER QUEBEC CONTINUES TO MOVE NORTHEAST AND HIGH PRESSURE BUILDS OVER THE SOUTHERN GREAT LAKES. A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE GREAT LAKES MONDAY AND MONDAY NIGHT. STRONG COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM WILL HAVE TO POTENTIAL TO PRODUCE GALE FORCE WIND GUSTS OVER MUCH OF LAKE HURON FROM EARLY TUESDAY MORNING THROUGH WEDNESDAY MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... GALE WATCH...LHZ361-LHZ362-LHZ363-LHZ462-LHZ463-LHZ464...FROM 4 AM TUESDAY TO 7 AM WEDNESDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT SHORT TERM...HLO LONG TERM....MR MARINE.......HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 634 PM EST SAT DEC 29 2007 .SHORT TERM...(TONIGHT AND SUNDAY) WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD TROUGH OVER THE CONUS WITH THE STRONGEST JET ENERGY WELL TO THE SOUTH. A WEAK SHORTWAVE TROUGH OVER NRN WI WAS SHEARING OUT AS IT MOVES INTO MORE CONFLUENT FLOR FROM THE GREAT LAKES INTO ERN CANADA. WEAK 275K-280K ISENTROPIC LIFT FROM NW WI TOWARD W UPPER MI SUPPORTED SOME LIGHT SNOW OR FLURRIES FROM ERN MN INTO NW WI. RADAR REFLECTIVITIES...PER KDLH RADAR...WERE MAINLY 10 DBZ OR LESS. LIGHT LAKE EFFECT SNOW SHOWERS ALSO CONTINUED INTO THE KEWEENAW AND NE CWA WITH WEAK 10-20 KT WRLY CBL FLOW. OTHERWISE...CLOUD SKIES PREVAILED ACROSS ALL BUT THE FAR SOUTH CWA. TONIGHT...EXPECT THE AREA OF WEAK ISENTROPIC LIFT WITH LIGHT SNOW OR FLURRIES TO CONTINUE MOVING NE. SO...SLIGHT CHANCE POPS WERE INCLUDED THIS EVENING TIL THE SHORTWAVE LIFTS NE OF THE AREA. THE NAM AND LCL HIGH RES WRF/ARW SUGGEST THAT THE WEAK WEST WINDS WILL ALLOW A LAKE INDUCED TROF TO DEVELOP FROM WRN LAKE SUPERIOR ACROSS THE KEWEENAW. LOW LEVEL CONV WITH THIS FEATURE COULD PROVIDE A FOCUS FOR ENHANCED LES AS 850 MB TEMPS AROUND -12C (LAKE-H8 DELTA TO TO AROUND 15C) AND INVERSION HEIGHTS ABOVE 7K FT(MOISTURE TO AT LEAST 10K FT) WILL FAVOR POTENTIAL FOR LIGHT TO MODERATE LES. HOWEVER...SINCE UNCERTAINTY REMAINS WITH THE DEVELOPMENT...PLACEMENT AND MOVEMENT OF THE TROUGH...SNOWFALL AMOUNTS IN THE 1-3 INCH RANGE WERE MENTIONED. HOWEVER...IF A STRONGER BAND DEVELOPS SEVERAL MORE INCHES WOULD BE EXPECTED. SUNDAY...ANY LINGERING SNOW SHOWERS SHOULD LIFT NORTHEAST AS MORE SW LARGE SCALE FLOW TAKES OVER. OTHERWISE...LOW LEVEL WAA WITH MOISTURE BENEATH A STRENGTHENING INVERSION SHOULD KEEP STRATUS IN PLACE. CANNOT RULE OUT A FEW FLURRIES BUT WOULD BE ISOLD/BRIEF. MOISTURE TO -10C AND INCREASING SFC DEWPOINT DEPRESSIONS SHOULD MINIMIZE ANY FZDZ POTENTIAL. .LONG TERM (SUN NIGHT THRU SAT)... SUN NIGHT THRU TUE...TROF OVER THE CNTRL INTO THE ERN CONUS WILL BEGIN TO SHARPEN DUE TO UPSTREAM RIDGE BUILDING ALONG THE W COAST. A COUPLE OF STRONGER SHORTWAVES WILL AFFECT THE GREAT LAKES (FIRST MON AND SECOND TUE)...BUT IT APPEARS THE BULK OF THE FORCING WITH EACH WILL PASS S OF THE FCST AREA. AT THE SFC...BROAD LOW PRES OVER THE NRN PLAINS SUN NIGHT WILL MOVE TO THE LWR LAKES BY TUE MORNING AND GRADUALLY BECOME MORE WELL DEFINED AS SECOND SHORTWAVE SWINGS INTO THE GREAT LAKES. WHILE THERE IS STILL SOME POTENTIAL OF S TO SW FLOW LES/LAKE ENHANCED SNOW TO AFFECT THE FAR ERN FCST AREA AHEAD OF LOW PRES...MANY OF THE MODELS ARE TRENDING AWAY FROM SRLY FLOW INTO UPPER MI SINCE LOW IS INITIALLY BROAD/POORLY DEFINED. UNTIL MODEL AGREEMENT BECOMES BETTER...WILL STAY ALONG THE LINES OF PREVIOUS FCSTS WHICH HAVE SHOWN SLIGHTLY HIGHER POPS OVER THE FAR ERN FCST AREA SUN NIGHT/MON TO COVER THE POTENTIAL. ELSEWHERE...THERE IS NOTHING SIGNIFICANT TO TIE PCPN CHANCES TO SUN NIGHT/MON. SINCE THE FCST AREA IS JUST AHEAD OF THE APPROACHING MAIN MIDLEVEL TROF AXIS...BEST COURSE OF ACTION IS PROBABLY TO MAINTAIN CONTINUITY WITH PREVIOUS FCST (LOW CHC POPS ACROSS THE BOARD). SECOND SHORTWAVE PASSING THRU THE GREAT LAKES MON NIGHT/TUE WILL OFFER A BETTER OPPORTUNITY FOR SHSN ACROSS THE FCST AREA. IT WILL ALSO GET LES GOING. IN RESPONSE TO THE SHORTWAVE...A SHARP SFC TROF WILL DROP ACROSS LAKE SUPERIOR INTO UPPER MI LATE MON NIGHT/TUE MORNING...TRIGGERING A PERIOD OF MDT TO POSSIBLY HVY LAKE ENHANCED SNOW FOR PROBABLY ALL AREAS NEAR THE LAKE AS WINDS SHIFT NRLY. PURE LES REGIME WILL THEN DEVELOP DURING THE DAY TUE INTO TUE NIGHT AS THE SHORTWAVE MOVES AWAY FROM THE AREA. LES WILL ALSO SHIFT AS NRLY WINDS TUE BACK NW TUE NIGHT. EXPECT THE LATE MON NIGHT/TUE PERIOD TO BE A HEADLINE EVENT FOR MOST IF NOT ALL THE COUNTIES BORDERING LAKE SUPERIOR. IT WILL CERTAINLY BE AN ADVY. WHETHER OR NOT WARNING AMOUNTS CAN BE REACHED WILL DEPEND ON HOW SIGNIFICANT THE LAKE ENHANCED PORTION OF THE EVENT WILL BE...AND THAT WON`T BE KNOWN UNTIL THE EVENT GETS CLOSER IN TIME. AT THE MOMENT...IT LOOKS LIKE AN ADVY WILL COVER IT. WED THRU SAT...BIG CHANGE IN THE PATTERN WILL OCCUR DURING THIS PERIOD AS ERN CONUS TROF SHIFTS TO THE WRN ATLANTIC...WRN NAMERICA RIDGE BROADENS AND SHIFTS EWD...AND TROFFING DEVELOPS JUST OFF THE W COAST. LATEST GFS/ECMWF RUNS CONTINUE TO SHOW VERY GOOD CONTINUITY WITH PREVIOUS RUNS OVER THE LAST SEVERAL DAYS...SUGGESTING A STRONG SIGNAL IS THERE FOR THIS CHANGE IN THE PATTERN. NEAR/SLIGHTLY BLO NORMAL TEMPS TUE/WED ASSOCIATED WITH TROF WILL TREND ABOVE NORMAL FOR FRI/SAT WITH WARM REGIME CONTINUING BEYOND THIS FCST PERIOD INTO AT LEAST EARLY NEXT WEEK. EXPECT THE BIGGEST IMPACT OF WARMING ON MIN TEMPS WHICH WILL LIKELY HAVE INCREASINGLY GREATER DEPARTURES FROM NORMAL THAN MAX TEMPS AS THE WARMING TREND LENGTHENS. WOULD NOT BE SURPRISED TO SEE TEMPS STRUGGLE TO FALL BACK BLO FREEZING AT NIGHT AT SOME POINT OVER THE WEEKEND/EARLY NEXT WEEK. AS FOR PCPN... LES WILL WIND DOWN WED AND SHOULD END WED NIGHT FROM W TO E AS SFC RIDGE PASSES AND WAA GETS UNDERWAY. GFS SUGGESTS ONE LAST SHORTWAVE WILL DROP SE TOWARD THE DEPARTING LONGWAVE TROF THU/FRI. ECMWF INDICATES THIS SHORTWAVE WILL PASS MUCH FARTHER TO THE N THAN THE GFS. SINCE THE GFS ENSEMBLES LEND SUPPORT FOR AN ECMWF TYPE SOLUTION...WILL LEAN STRONGLY TOWARD ITS SOLUTION FROM THU ONWARD. NICE TO SEE THAT THE 12Z GFS TRENDED TOWARD THE PREFERRED ECMWF SOLUTION. ALTHOUGH AIRMASS LOOKS QUITE DRY...STRONG WAA (850MB WINDS TO 50KT) SUGGESTS MAINTAINING CONTINUITY WITH PREVIOUS FCST OF LOW POPS FOR -SN THU. FIRST SHORTWAVE HEADING E FROM THE NEW TROF JUST OFF THE W COAST SHOULD MAKE A RUN ACROSS THE PLAINS TOWARD THE GREAT LAKES SAT...BRINGING THE POSSIBILITY OF LIGHT RAIN AND/OR SNOW. AT LEAST ONE PREDOMINANT RAIN EVENT SEEMS LIKELY DURING THE UPCOMING PERIOD OF WELL ABOVE NORMAL TEMPS THIS WEEKEND INTO EARLY NEXT WEEK. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... MVFR CIGS AND FLURRIES SHOULD HANG ON AT KCMX THROUGH MUCH OF TONIGHT WITH DECENT UPSTREAM SFC-700 MB MOISTURE AND ONSHORE WRLY FLOW. AS THE WIND SWINGS AROUND TO THE SW LATE TONIGHT...LAKE EFFECT SHOULD SHUT OFF...BUT CLOUDS WILL HANG ON THROUGH SUNDAY THERE. SW TO W WINDS AT KSAW SHOULD LIMIT ANY LES CHANCES. HOWEVER... THE HIGH MVFR CLOUD DECK WILL LINGER AS MODEL FCST SOUNDINGS SHOW AN INVERSION PERSISTING AT 3500 FT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EVEN THOUGH WINDS WILL GENERALLY BE LIGHT TONIGHT WITH A WEAK TROUGH IS EXPECTED TO DEVELOP OVER LAKE SUPERIOR TONIGHT WITH THE POTENTIAL FOR SOMEWHAT STRONGER WSW WINDS JUST SOUTH OF THE TROUGH AXIS. OTHERWISE WITH WEAK HIGH PRESSURE SLIDING EAST OF THE REGION WINDS WILL REMAIN BLO 25 KNOTS. A LOW PRESSURE SYSTEM TAKING SHAPE IN THE NORTHERN PLAINS WILL MOVE INTO THE UPPER GREAT LAKES ON MONDAY. A TIGHT NRLY GRADIENT WILL DEVELOP ON THE BACKSIDE OF THE LOW ON TUE AS STRONG HIGH PRESSURE BUILDS INTO THE PLAINS. FOR NOW...LEFT IN WINDS TO 30 KT WHICH MAY NEED TO BE RAISED TO GALES AS CONFIDENCE IN THE SURFACE PRESSURE FIELD INCREASES. LOOK FOR WINDS TO DIMINISH TO BLO 25 KTS BY WED EVENING AS THE HIGH PRES RIDGE FROM THE PLAINS MOVES OVER THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...JLB LONG TERM...ROLFSON AVIATION...GJM MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 314 PM EST SAT DEC 29 2007 .SHORT TERM...THROUGH TONIGHT SURFACE HIGH PRESSURE WILL BUILD OVER THE OHIO VALLEY TONIGHT AND EXTEND UP INTO THE SOUTHERN GREAT LAKES. THIS WILL BRING DRY WEATHER AND ALLOW WINDS TO RELAX. MAIN FORECAST CHALLENGE FOR THE SHORT TERM REMAINS CENTERED AROUND THE POSSIBLE BREAK-UP OF THE STRATUS DECK ENTRENCHED OVER THE REGION. WESTERLY FLOW OFF LAKE MICHIGAN HAS HELPED KEEP THIS DECK INTACT THIS AFTERNOON. 12Z DTX SOUNDING INDICATES THE MIXED LAYER TO BE POTENTIALLY 5000 FEET DEEP...BUT FORECAST SOUNDINGS SHOW THIS LAYER SHRINKING THROUGH THE AFTERNOON AS INVERSION HEIGHTS LOWER. FORECAST SOUNDINGS ALSO SHOW THE AIRMASS REMAINING FAIRLY SATURATED IN THE LOWER LEVELS THROUGH MUCH OF THE AFTERNOON...BEFORE SOME DRIER AIR IS MIXED DOWN DURING THE LATE AFTERNOON. MODELS LOOK TOO AGGRESSIVE WITH THIS MIXING AS THEY ARE TOO WARM WITH SURFACE TEMPERATURES AND AT LEAST 1000 FEET TOO LOW WITH THE INVERSION HEIGHTS (WHERE DRIER AIR RESIDES ABOVE). THINK THE LOWER LAYERS WILL STAY A LITTLE MORE MOIST THAN INDICATED...FAVORING A MORE INTACT DECK. WATER VAPOR IMAGERY SHOWS A SMALL UPPER SHORTWAVE TRACKING UP THROUGH ILLINOIS AND INDIANA. NAM AND RUC MODELS HAVE THE BEST HANDLE ON THIS FEATURE...BUT LARGELY SHEAR IT OUT BEFORE IT REACHES THE EASTERN PORTION OF THE MICHIGAN/OHIO BORDER BY 00Z. UPSTREAM OVER ILLINOIS...THIS FEATURE HAS HELPED CLEAR OUT MOST OF THE STRATUS. HOWEVER...NOT SURE IT WILL BE STRONG ENOUGH TO BREAK UP THE DECK OVER THE SOUTHERN FORECAST AREA. TAKING INTO ACCOUNT ALL THIS INFORMATION...WILL KEEP THE DECK LARGELY INTACT FOR THE AFTERNOON FORECAST PACKAGE. EXPECTING A FEW BREAKS TO APPEAR DURING THE LATE AFTERNOON/EARLY EVENING HOWEVER. CIRRUS SHIELD WILL EXPAND OVERNIGHT FROM THE SOUTHERN PLAINS TO THE OHIO VALLEY AS THE BROAD UPPER TROUGH CROSSING THE ROCKIES BECOMES MORE AMPLIFIED. HIGH CLOUDS WILL START TO SPREAD INTO THE SOUTHERN HALF OF THE FORECAST AREA DURING THE EARLY MORNING...THROUGH THEY WILL ARRIVE TOO LATE TO HAVE A BIG IMPACT ON TEMPERATURES. OVERNIGHT LOWS WILL RUN 8 TO 10 DEGREES BELOW LAST NIGHT`S MILD READINGS...BOTTOMING OUT IN THE LOW TO MID 20S. && .LONG TERM... HIGH PRESSURE SLIDES EAST ON SUNDAY...AS A SHORTWAVE DIGS INTO THE TENNESSEE VALLEY AND INDUCES COASTAL ATLANTIC CYCLOGENESIS. TEMPERATURES ON SUNDAY WILL REBOUND SLIGHTLY FROM TODAY...AS THE GRADIENT TAKES ON MORE OF A SOUTHERLY COMPONENT AND THINNER HIGH/MID CLOUDS CONTROL THE SKY CONDITION. BOTH THE NAM AND GFS HINT AT SECONDARY WEAK SFC LOW DEVELOPMENT WEST OF THE APPALACHIANS... ALLOWING FOR A NARROW AREA OF LGT PCPN TO DEVELOP ALONG THE DEFORMATION AXIS LIFTING NORTHEAST FROM SOUTHWEST OHIO THROUGH LAKE ERIE SUNDAY EVENING. THE VERY NORTHWEST EDGE OF THIS MAY CLIP EXTREME SOUTHEAST LOWER MI...AND WILL JUST INTRODUCE A SLIGHT CHANCE POP THROUGH 06Z FROM MONROE TO MACOMB COUNTY FOR VERY LGT SNOW SHOWERS WITH NO ACCUMS EXPECTED. OTHERWISE...WILL BACK OFF ON POPS FOR THE OVERNIGHT PERIOD...AS MODEL CONSENSUS REMAINS SUFFICIENT THAT IMPACTS FROM THE NEXT APPROACHING SYSTEM WILL HOLD UNTIL MONDAY. THIS SYSTEM BECOMES THE MAIN FOCUS FOR THIS FORECAST PACKAGE... LIKELY IMPACTING MUCH OF SOUTHEAST LOWER MICHIGAN LATE ON NEW YEARS EVE. SHORTWAVE MOVING ONSHORE ACROSS BRITISH COLUMBIA LATE TONIGHT...WILL DROP SOUTHEAST WITHIN THE MEAN CENTRAL U.S. TROUGH... STRENGTHENING SLIGHTLY AND INDUCING SFC LOW DEVELOPMENT AS IT MOVES INTO THE NORTHERN PLAINS/GREAT LAKES THROUGH EARLY MONDAY. IN RESPONSE TO THE DIFFICULTY IN RESOLVING SUCH A LOW AMPLITUDE WAVE BEFORE IT CAN BE PROPERLY SAMPLED...THE MODELS CONTINUE TO STRUGGLE WITH THE FINER DETAILS WITH THIS SYSTEM...WITH THE BIGGEST STRUGGLES INVOLVING WHERE TO PLACE THE BEST FORCING AND ASSOCIATED MAIN MOISTURE AXIS. ALL MODELS AGREE ON TAKING THE SFC LOW FROM WEST TO EAST ACROSS NORTHERN/CENTRAL LOWER MI. HOWEVER...THE NAM (WITH SUPPORT FROM SREF OUTPUT) MAINTAINS A MUCH MORE COMPACT SYSTEM...AND FOCUSES THE BULK OF THE PCPN FROM THE SAGINAW VALLEY NORTHWARD. MEANWHILE...THE GFS INDICATES A MUCH BROADER SYSTEM...WITH A HIGHER AXIS OF QPF (.1-.2") SOUTH OF THE SFC LOW FOCUSED ALONG THE FRONTAL CONVERGENCE ZONE AND WITHIN AN AREA OF ENHANCED FORCING PROVIDED BY THE SHORTWAVE. THE ECMWF SHOWS A SIMILAR DEPICTION...ONLY WITH MUCH LESS QPF IN A SHORTER DURATION. GIVEN THE POOR CONSENSUS...WILL GENERALLY TAKE A BLEND...ADJUSTING PCPN AMOUNTS UP SLIGHTLY ACROSS THE SOUTH BUT UNDERCUTTING THE HIGHER AMOUNTS SHOWN BY THE GFS. THIS WILL MAKE SNOW ACCUMULATIONS FROM A DUSTING TO 2 INCHES POSSIBLE AREAWIDE MONDAY AFTERNOON/EVENING...WITH THE POTENTIAL FOR NARROW CORRIDOR OF HIGHER END AMOUNTS UP TO 3 INCHES SOMEWHERE WITHIN THE CWA. DECENT MODEL AGREEMENT EXISTS WITH REGARD TO THE PATTERN EVOLUTION FOR MID-WEEK...WITH A DEEPENING LONGWAVE TROUGH LIFTING FROM THE CENTRAL TO EASTERN CONUS...WHILE RIDGING BUILDS ACROSS THE WEST. THIS AMPLIFIED FLOW WILL LIKELY BRING THE COLDEST AIRMASS OF THE SEASON SOUTHWARD INTO THE GREAT LAKES...AS COLD AIR ADVECTION DEVELOPS TUESDAY BEHIND THE DEPARTING NEW YEARS EVE SYSTEM...WITH A REINFORCING ARCTIC COLD FRONT ARRIVING BY TUESDAY NIGHT. GREAT LAKES REGION WILL LIKELY SEE JUST A GLANCING BLOW WITH THIS ARCTIC SURGE WITH THE BETTER DROP IN 850 MB TEMPS/THICKNESSES OCCURRING ACROSS THE PLAINS/MIDWEST...WITH SOME AIRMASS MODIFICATION BY THE UPSTREAM LAKES LIKELY UPON ARRIVAL TUES NGT/WEDNESDAY. NONETHELESS...HIGHS ONLY IN THE LOW/MID 20S UNDER A GUSTY NORTHWEST GRADIENT STILL LOOKS REASONABLE ON WEDNESDAY GIVEN THE PROJECTED 850MB TEMPS. A WEAKENING LOW LEVEL WIND FIELD AND PARTIAL CLEARING WILL BRING SOME ENHANCED RADIATIONAL COOLING POTENTIAL WED NGT...AND WILL REMAIN BELOW GUIDANCE WITH MANY LOCATIONS (OUTSIDE OF THE DETROIT URBAN HEAT ISLAND) SEEING LOWS IN THE 8-12F RANGE THURSDAY MORNING. THE STRONG COLD AIR ADVECTION WITH INCREASINGLY FAVORABLE 850 MB TEMPS/LAPSE RATES...ENHANCED VORTICITY WITHIN THE BROAD CYCLONIC FLOW...AND ADDED LOW LEVEL CONVERGENCE PROVIDED BY THE ARCTIC FRONT...WILL PROMOTE SCATTERED TO NUMEROUS SNOW SHOWER ACTIVITY TUESDAY AND TUESDAY NIGHT. MODELS REALLY KEYING ON THE ARCTIC BOUNDARY FOR MORE ORGANIZED DEVELOPMENT FROM 18-03Z LATE TUESDAY...WITH POTENTIAL SNOW ACCUMS OF 1-2 INCHES (HIGHEST NORTH). MODELS INSISTING ON A QUICK RECOVERY OF THE AIRMASS BACK TOWARD MORE SEASONABLE TEMPERATURE READINGS BY THURSDAY AND FRIDAY...WITH PRONOUNCED WARM AIR ADVECTION/RISING THICKNESSES DEVELOPING ON THE BACKSIDE OF A DEPARTING SFC HIGH. WHILE THE GFS/ECMWF/CANADIAN AND ENSEMBLES ALL AGREE ON THIS...WILL CONTINUE TO TEMPER THE WARMUP SLIGHTLY THURSDAY THE COLD MORNING START AND THE TYPICAL MODEL BIAS FOR SCOURING OUT AN ARCTIC AIRMASS TOO QUICKLY. ALSO...THE UPSTREAM UPPER RIDGE LOOKS TO DAMPEN AS IT ARRIVES...THUS LESSENING THE OVERALL DEPTH/STRENGTH OF THE SOUTHWEST RETURN FLOW. TEMPERATURES WILL RETURN TO MORE SEASONABLE READINGS BY FRIDAY. && .MARINE... WINDS WILL CONTINUE TO DIMINISH ACROSS THE MICHIGAN NEARSHORE WATERS THROUGH THE EVENING AND OVERNIGHT AS LOW PRESSURE OVER QUEBEC CONTINUES TO MOVE NORTHEAST AND HIGH PRESSURE BUILDS OVER THE SOUTHERN GREAT LAKES. A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE GREAT LAKES MONDAY AND MONDAY NIGHT. STRONG COLD AIR ADVECTION IN THE WAKE OF THIS SYSTEM WILL HAVE TO POTENTIAL TO PRODUCE GALE FORCE WIND GUSTS OVER MUCH OF LAKE HURON FROM EARLY TUESDAY MORNING THROUGH WEDNESDAY MORNING. && .PREV DISCUSSION...ISSUED 233 PM EST SAT DEC 29 2007 AVIATION... WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL DISTURBANCE MOVING THROUGH ILLINOIS THIS AFTERNOON. THIS DISTURBANCE WILL BRUSH THE MICHIGAN/OHIO BORDER BY EARLY EVENING. WILL SEE A FEW BREAKS IN THE STRATUS DECK LATE THIS AFTERNOON OVER DTW AND DET AS THIS FEATURE DRAWS CLOSER...BUT DECK WILL REMAIN LARGELY INTACT. MAY SEE SOME MORE BREAKS DEVELOP AFTER 03Z TONIGHT AS SOUTHWEST FLOW BRINGS IN SOME SLIGHTLY DRIER AIR. MVFR CEILINGS WILL PREVAIL THROUGH THE AFTERNOON AND INTO THE EARLY EVENING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY AND THE NEARSHORE WATERS FROM PORT AUSTIN TO HARBOR BEACH...UNTIL 7 PM SATURDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...HLO LONG TERM....MR MARINE.......HLO AVIATION.....HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1245 PM EST SAT DEC 29 2007 UPDATED FOR AVIATION DISCUSSION .SYNOPSIS... SFC LOW PRES OVER LAKE HURON LATE IN THE EVENING HAS QUICKLY EJECTED INTO QUEBEC. SNOW OVER THE EASTERN U.P. HAS TAPERED OFF AND LAKE EFFECT SNOW HAS KICKED IN ACROSS THE FAR WEST...ESPECIALLY AFTER AN EAST-WEST ORIENTED TROUGH DIPPED SOUTHWARD ACROSS THE KEWEENAW PENINSULA. THE TROUGH WILL SHIFT EASTWARD THIS MORNING AS THE LOW MOVES OUT. 500MB RUC ANALYSIS AND WATER VAPOR IMAGERY SHOW A STRONG SHORTWAVE OVER SOUTHERN LOWER MI WITHIN A NEGATIVELY TILTED TROUGH THAT IS SITUATED ACROSS THE CONUS. THIS SHORTWAVE WILL BE RESPONSIBLE FOR THE WEATHER IN THE GREAT LAKES AREA ON SUN AND MONDAY. && .DISCUSSION... TODAY AND TONIGHT...EXPECT LIGHT LAKE EFFECT SNOW IN REGIONS FAVORED BY NW FLOW TO CONTINUE THROUGH THE DAY...ESPECIALLY EAST OF MUNISING. 850MB TEMPS WILL BE AROUND -12C. WINDS WILL BACK WESTWARD THROUGHOUT THE AFTERNOON...DIMINISHING THE LAKE EFFECT IN THE FAR WEST SIGNIFICANTLY. CHANGED LIKELY POPS IN IRONWOOD TO SCATTERED FLURRIES DUE TO THE WSW WINDS EXPECTED. DURING THE OVERNIGHT HOURS...MODELS ARE INDICATING PCPN ASSOCIATED WITH A CONVERGENCE ZONE ORIENTED WEST TO EAST ACROSS LAKE SUPERIOR. THE HI-RES LOCAL WRF MODEL AND ECMWF SHOW THE PCPN BAND LINED UP JUST SOUTH OF HOUGHTON AND THE NAM AND RUC13 PUT IT ACROSS KEWEENAW COUNTY. THE MODELS ALL INDICATE THE BAND WILL LIFT NORTHWARD LATE SUNDAY NIGHT AS SOUTHERLY WINDS TAKE OVER. CHANGED WX GRIDS TO REFLECT THE UNCERTAINTY OF WHERE THIS BAND OF LIGHT SNOW WILL SET UP. ALSO INCREASED CLOUD COVER TONIGHT DUE TO THE HIGH RH VALUES AT LOW AND MID LEVELS. WITH CLOUDIER SKIES...INCREASED OVERNIGHT LOWS A LITTLE. SUNDAY...THE SHORTWAVE OVER THE WASHINGTON/OREGON BORDER WILL MAKE ITS WAY EASTWARD ALONG A WEAK 500MB TROUGH ACROSS THE NORTHERN PLAINS ON SAT NIGHT AND ARRIVE IN THE UPPER GREAT LAKES AREA SUNDAY MORNING. SOUTHERLY FLOW AND WEAK ISENTROPIC LIFT MAY CONTRIBUTE TO SOME FREEZING DRIZZLE AND/OR SNOW. FOR NOW...KEPT GOING SCHC SNOW ACROSS THE REGION...WITH THE EXCEPTION OF LAKE MICHIGAN LAKE EFFECT AREAS. SUNDAY NIGHT THROUGH TUESDAY...THE UNCERTAINTY ARISES SUN NIGHT AS TO WHEN TWO SHORTWAVES OVER THE NORTHERN PLAINS WILL PHASE TOGETHER. THE ASSOCIATED WEAK SFC LOW WILL TRACK ACROSS NORTHERN WI AND POSSIBLY UPPER MI ON MON. GFS IS THE FURTHEST SOUTH OF THE SOLNS AND THE ECMWF/CANADIAN/UKMET COMPROMISE IS THE PREFERRED SOLN. WITH THIS UNCERTAINTY...KEPT WITH GOING FCST OF A CHANCE OF SNOW ACROSS THE REGION WITH HIGHER POPS IN NW LES FAVORED REGIONS. BEHIND THIS LOW MONDAY NIGHT THROUGH TUESDAY...LAKE EFFECT SNOW WITH COLD...NNW WINDS WILL TAKE CONTROL OF THE CWA. WENT WITH FAIRLY MODERATE QPF (AROUND 0.06) FOR LAKE EFFECT...WHICH MAY BE A LITTLE OVERDONE... GIVEN LACK OF MOISTURE WITH THE SYSTEM. WILL NEED TO TAKE A CLOSER LOOK AT THIS. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MVFR CIGS AND FLURRIES SHOULD HANG ON AT KCMX THROUGH MUCH OF THE DAY WITH DECENT UPSTREAM SFC-700 MB MOISTURE AND ONSHORE WRLY FLOW. WINDS BACKING WEST AT KSAW SHOULD LIMIT ANY LES CHANCES. HOWEVER...THE HIGH MVFR CLOUD DECK MAY LINGER AS MODEL FCST SOUNDINGS SHOW AN INVERSION PERSISTING AT 3500 FT. FOCUSED LOW LEVEL CONVERGENCE FROM WEST LAKE SUPERIOR THROUGH THE KEWEENAW ALONG A WEAK TROUGH SHOULD BRING AN INCREASE IN LES TONIGHT AT KCMX WITH IFR CIGS/VSBY POSSIBLE. THE LES SHOULD END SUNDAY MORNING AS WINDS BACK TO SW OVER THE AREA. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NW GRADIENT SLACKENS OVER LAKE SUPERIOR TODAY AS THE SURFACE LOW LIFTS NE INTO QUEBEC. NW WINDS WILL DECREASE TO 20 KT OR LESS BY AFTERNOON. WEAK HIGH PRESSURE MOVING OVER THE REGION SUNDAY WILL KEEP WINDS BLO 25 KNOTS. A LOW PRESSURE SYSTEM TAKING SHAPE IN THE NORTHERN PLAINS WILL MOVE INTO THE UPPER GREAT LAKES ON MONDAY. A TIGHT NRLY GRADIENT WILL DEVELOP ON THE BACKSIDE OF THE LOW ON TUE AS STRONG HIGH PRESSURE BUILDS INTO THE PLAINS. FOR NOW...LEFT IN WINDS TO 30 KT BUT WOULDN`T BE SURPRISED THAT GALE FORCE GUSTS COULD OCCUR OVER ERN SUPERIOR. LOOK FOR WINDS TO DIMINISH TO BLO 25 KTS BY WED EVENING AS THE HIGH PRES RIDGE FROM THE PLAINS MOVES OVER THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...MRC AVIATION...JV MARINE...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 500 AM EST SAT DEC 29 2007 .SYNOPSIS... SFC LOW PRES OVER LAKE HURON LATE IN THE EVENING HAS QUICKLY EJECTED INTO QUEBEC. SNOW OVER THE EASTERN U.P. HAS TAPERED OFF AND LAKE EFFECT SNOW HAS KICKED IN ACROSS THE FAR WEST...ESPECIALLY AFTER AN EAST-WEST ORIENTED TROUGH DIPPED SOUTHWARD ACROSS THE KEWEENAW PENINSULA. THE TROUGH WILL SHIFT EASTWARD THIS MORNING AS THE LOW MOVES OUT. 500MB RUC ANALYSIS AND WATER VAPOR IMAGERY SHOW A STRONG SHORTWAVE OVER SOUTHERN LOWER MI WITHIN A NEGATIVELY TILTED TROUGH THAT IS SITUATED ACROSS THE CONUS. THIS SHORTWAVE WILL BE RESPONSIBLE FOR THE WEATHER IN THE GREAT LAKES AREA ON SUN AND MONDAY. && .DISCUSSION... TODAY AND TONIGHT...EXPECT LIGHT LAKE EFFECT SNOW IN REGIONS FAVORED BY NW FLOW TO CONTINUE THROUGH THE DAY...ESPECIALLY EAST OF MUNISING. 850MB TEMPS WILL BE AROUND -12C. WINDS WILL BACK WESTWARD THROUGHOUT THE AFTERNOON...DIMINISHING THE LAKE EFFECT IN THE FAR WEST SIGNIFICANTLY. CHANGED LIKELY POPS IN IRONWOOD TO SCATTERED FLURRIES DUE TO THE WSW WINDS EXPECTED. DURING THE OVERNIGHT HOURS...MODELS ARE INDICATING PCPN ASSOCIATED WITH A CONVERGENCE ZONE ORIENTED WEST TO EAST ACROSS LAKE SUPERIOR. THE HI-RES LOCAL WRF MODEL AND ECMWF SHOW THE PCPN BAND LINED UP JUST SOUTH OF HOUGHTON AND THE NAM AND RUC13 PUT IT ACROSS KEWEENAW COUNTY. THE MODELS ALL INDICATE THE BAND WILL LIFT NORTHWARD LATE SUNDAY NIGHT AS SOUTHERLY WINDS TAKE OVER. CHANGED WX GRIDS TO REFLECT THE UNCERTAINTY OF WHERE THIS BAND OF LIGHT SNOW WILL SET UP. ALSO INCREASED CLOUD COVER TONIGHT DUE TO THE HIGH RH VALUES AT LOW AND MID LEVELS. WITH CLOUDIER SKIES...INCREASED OVERNIGHT LOWS A LITTLE. SUNDAY...THE SHORTWAVE OVER THE WASHINGTON/OREGON BORDER WILL MAKE ITS WAY EASTWARD ALONG A WEAK 500MB TROUGH ACROSS THE NORTHERN PLAINS ON SAT NIGHT AND ARRIVE IN THE UPPER GREAT LAKES AREA SUNDAY MORNING. SOUTHERLY FLOW AND WEAK ISENTROPIC LIFT MAY CONTRIBUTE TO SOME FREEZING DRIZZLE AND/OR SNOW. FOR NOW...KEPT GOING SCHC SNOW ACROSS THE REGION...WITH THE EXCEPTION OF LAKE MICHIGAN LAKE EFFECT AREAS. SUNDAY NIGHT THROUGH TUESDAY...THE UNCERTAINTY ARISES SUN NIGHT AS TO WHEN TWO SHORTWAVES OVER THE NORTHERN PLAINS WILL PHASE TOGETHER. THE ASSOCIATED WEAK SFC LOW WILL TRACK ACROSS NORTHERN WI AND POSSIBLY UPPER MI ON MON. GFS IS THE FURTHEST SOUTH OF THE SOLNS AND THE ECMWF/CANADIAN/UKMET COMPROMISE IS THE PREFERRED SOLN. WITH THIS UNCERTAINTY...KEPT WITH GOING FCST OF A CHANCE OF SNOW ACROSS THE REGION WITH HIGHER POPS IN NW LES FAVORED REGIONS. BEHIND THIS LOW MONDAY NIGHT THROUGH TUESDAY...LAKE EFFECT SNOW WITH COLD...NNW WINDS WILL TAKE CONTROL OF THE CWA. WENT WITH FAIRLY MODERATE QPF (AROUND 0.06) FOR LAKE EFFECT...WHICH MAY BE A LITTLE OVERDONE... GIVEN LACK OF MOISTURE WITH THE SYSTEM. WILL NEED TO TAKE A CLOSER LOOK AT THIS. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SNOW WILL CONTINUE OVERNIGHT AT BOTH SITES WITH MOSTLY MVFR CONDITIONS NOW AS THE SNOW PULLS OUT. WINDS ARE MORE NW NOW...SO UPSLOPE BECOMES LESS OF AN ISSUE AND DO NOT THINK IFR/LIFR WILL HAPPEN THAT LONG AT BOTH SITES TO INCLUDE IN THE TAFS. CONDITIONS WILL CONTINUE TO IMPROVE AFTER 12Z SAT AS LOW PRESSURE SYSTEM PRODUCING THE SNOW SHIFTS EAST OF THE AREA AND DRIER AIR STARTS TO MOVE IN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NW GRADIENT SLACKENS OVER LAKE SUPERIOR TODAY AS THE SURFACE LOW LIFTS NE INTO QUEBEC. NW WINDS WILL DECREASE TO 20 KT OR LESS BY AFTERNOON. WEAK HIGH PRESSURE MOVING OVER THE REGION SUNDAY WILL KEEP WINDS BLO 25 KNOTS. A LOW PRESSURE SYSTEM TAKING SHAPE IN THE NORTHERN PLAINS WILL MOVE INTO THE UPPER GREAT LAKES ON MONDAY. A TIGHT NRLY GRADIENT WILL DEVELOP ON THE BACKSIDE OF THE LOW ON TUE AS STRONG HIGH PRESSURE BUILDS INTO THE PLAINS. FOR NOW...LEFT IN WINDS TO 30 KT BUT WOULDN`T BE SURPRISED THAT GALE FORCE GUSTS COULD OCCUR OVER ERN SUPERIOR. LOOK FOR WINDS TO DIMINISH TO BLO 25 KTS BY WED EVENING AS THE HIGH PRES RIDGE FROM THE PLAINS MOVES OVER THE REGION. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/DISCUSSION...MRC AVIATION...GM MARINE...JV mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 634 PM EST FRI DEC 28 2007 UPDATED FOR AVIATION DISCUSSION .SHORT TERM (TONIGHT AND SATURDAY)... WV LOOP AND RUC ANALYSIS SHOW NEGATIVE TILTED SHORTWAVE LIFTING INTO SOUTHERN LK MICHIGAN. 250MB JET CORE OVR IL INTO LWR MI SO SHORTWAVE SHOULD CONTINUE TO LIFT INTO LWR MI INSTEAD OF COME ANY FURTHER TO THE NORTH. SFC REFLECTION WITH THE WAVE IS LOW PRESSURE NEAR 1010MB IN THE VCNTY OF CHICAGO. UPR LEVEL FEATURES AND DEEP MOISTURE INFLOW ARE MAIN INSTIGATORS FOR BROAD SWATH OF SNOW FM EASTERN WI TO SOUTH CENTRAL UPR MI AND INTO WESTERN LWR MI. THUS FAR HEAVIEST SNOW WITH RATES OF 1-2"/HR ARE ALLIGNED FM CNTRL LK MI INTO NRN LWR MI. AS H85 LOW PASSES FM NORTHERN IL INTO NE LWR MI BY THIS EVENING AXIS OF HEAVIEST SNOW SHOULD MISS THE CWA. LIGHT TO MODERATE SNOW WILL AFFECT THE CWA...WITH THE HEAVIEST FALLING CLOSEST TO THE TRACK OF H85 LOW...BASICALLY ALONG THE LAKE MICHIGAN SHORELINE. ENE WINDS FLOWING OFF NORTHERN LK MICHIGAN AND 850MB TEMPS AROUND -10C MAY SETUP LAKE ENHANCED SNOW OVER NORTHERN PORTIONS OF MENOMINEE AND SOUTHWEST PORTIONS OF DELTA THIS EVENING. WINDS BACK QUICKLY TO THE NORTH BY LATE EVENING SO ALTHOUGH LOCALIZED AMOUNTS TO 6" ARE POSSIBLE ELECT TO NOT UPGRADE TO A WARNING SINCE MOST OF THE AREA WILL ONLY SEE ADVY LEVEL SNOW AMOUNTS. MEANWHILE...LARGE SCALE LIFT AND ADEQUATE OVER WATER INSTABILITY COULD PRODUCE SOME LAKE ENHANCEMENT OFF LAKE SUPERIOR TONIGHT. INITIALLY...NORTHERN PORTIONS OF KEWEENAW ARE FAVORED AS WINDS THROUGH H85 ARE FM THE ENE. HIGHER TERRAIN OF NORTH CENTRAL AND WESTERN CWA BECOMES MORE INVOLVED BY LATE EVENING AS WINDS BACK NNE ALONG DEVELOPING SFC TROUGH EXTENDING WESTWARD FM THE LOW PRESSURE OVER LWR MI. H95 CONVERGENCE STRENGTHENING ALONG THE TROUGH FM 03Z-09Z AND H85 COLD AIR ADVECTION WITH TEMPS LOWERING TO -12C SUPPORTS AN ADDITIONAL 1-2" SNOW ADDED ONTO THE SYNOPTIC TOTALS FM THE SYSTEM. AS FAR AS OUR GOING HEADLINES ARE CONCERNED...SEE NO NEED TO CHANGE THEM ATTM. HEAVIST SYNOPTIC SNOW IS JUST GOING TO GRAZE LK MICHIGAN ZONES SO THE ADVY LOOKS FINE FOR THOSE AREAS AND ANY ENHANCEMENT OFF LK SUPERIOR WILL BE LOCALIZED AND FAIRLY BRIEF. LIKELY SNOW SHOWERS SHOULD CONTINUE INTO SATURDAY NEAR LK SUPERIOR...ALTHOUGH DRY AIR SHOWING UP BLO H9 IN SOUNDINGS AND MINIMAL LIFT IN THE CLOUD LAYER WILL LIMIT ADDITIONAL ACCUMS. .LONG TERM (SAT NIGHT THRU FRI)... SAT NIGHT...850MB TEMPS OF -12 TO -13C WILL BE SUFFICIENT FOR SOME LES. INTERESTING ASPECT WILL BE THE LOW-LEVEL WIND FIELDS. GFS/NAM/REGIONAL CANADIAN ALL SHOW A CONVERGENCE ZONE SETTING UP W TO E OVER LAKE SUPERIOR...INITIALLY EXTENDING ACROSS THE KEWEENAW IN THE EVENING. GFS AND REGIONAL CANADIAN SHOW THIS ZONE SHIFTING N DURING THE NIGHT WHILE THE NAM LINGERS IT ACROSS THE NRN PART OF THE KEWEENAW. SINCE THE CANADIAN MODEL TYPICALLY DOES WELL WITH WINDS OVER LAKE SUPERIOR AND IT IS SUPPORTED BY THE GFS AND UKMET AS WELL...WILL DISREGARD THE NAM SOLUTION. WITH DEEP MOISTURE UPWARDS OF 7KFT...THERE COULD BE A FEW INCHES OF ACCUMULATION ACROSS THE KEWEENAW BEFORE CONVERGENCE ZONE SHIFTS N. WILL ALSO INCLUDE CHC POPS E OF MUNISING IN THE EVENING BEFORE WINDS BACK SW. ELSEWHERE... EXPECT DRY WEATHER SAT NIGHT. SUN/MON...TROF OVER THE CNTRL CONUS WILL BEGIN TO SHARPEN DUE TO UPSTREAM RIDGE BUILDING ALONG THE W COAST. A COUPLE OF SHORTWAVES WILL AFFECT THE UPPER LAKES...BUT NOTHING APPEARS WELL DEFINED AT THE MOMENT. WITH THE LACK OF FOCUSED FORCING...PCPN SHOULD GENERALLY BE ON LIGHT SIDE WHEN IT OCCURS. WILL CONTINUE TO CARRY CHC POPS SUN/MON DUE TO UNCERTAIN TIMING OF SHORTWAVES...BUT WILL UP POPS SOME ON MON DUE TO REASONABLE AGREEMENT ON SFC LOW AND STRONGER SHORTWAVE IN THE VCNTY AT THAT TIME. IF WINDS TAKE ON ENOUGH SRLY COMPONENT AHEAD OF LOW...SOME LAKE ENHANCED SNOW OFF LAKE MICHIGAN WILL BE POSSIBLE OVER THE FAR ERN FCST AREA SUN/MON. HAVE GENERALLY CARRIED HIGHEST POPS IN THAT AREA TO COVER THE POTENTIAL. TUE THRU FRI...THE BEGINNING OF A BIG SWING IN THE PATTERN IS EXPECTED DURING THIS PERIOD AS CNTRL/ERN CONUS TROF SHIFTS TO THE WRN ATLANTIC AND RIDGE ALONG THE W COAST BROADENS AND SHIFTS EWD. DESPITE WELL OUT INTO THE MODEL RUNS...THE GFS/ECMWF HAVE SHOWN VERY GOOD CONTINUITY ON THIS CHANGE OVER THE LAST SEVERAL DAYS... SUGGESTING A STRONG SIGNAL IS THERE. NEAR/SLIGHTLY BLO NORMAL TEMPS TUE/WED ASSOCIATED WITH TROF WILL TREND ABOVE NORMAL BY FRI WITH WARMING ONLY STRENGTHENING BEYOND THIS FCST PERIOD THRU NEXT WEEKEND. GIVEN VERY LOW SUN ANGLE THIS TIME OF YEAR...WARMING THAT OCCURS ALOFT WILL CERTAINLY NOT BE COMPLETELY REALIZED AT THE SFC...ESPECIALLY EARLY IN THE WARMING TREND WHICH COVERS THIS PERIOD OF THE FCST. BIGGEST IMPACT WILL BE ON MIN TEMPS WHICH WILL HAVE INCREASINGLY GREATER DEPARTURES FROM NORMAL THAN HIGH TEMPS AS THE WARMING TREND LENGTHENS. AS FOR PCPN...EXPECT DECENT LES TUE INTO EARLY WED... ESPECIALLY TUE AS GFS/ECMWF SHOW A SHORTWAVE DROPPING THRU THE AREA. COULD SEE A PERIOD OF HVY SNOW AS THAT SHORTWAVE PASSES. WIND FLOW WILL GENERALLY BE NW THOUGH IT SHOULD GO NRLY FOR A TIME WITH TUE SHORTWAVE PASSAGE...SO ALL AREAS NEAR LAKE SUPERIOR WILL GET IN ON ACCUMULATING LES. LES WILL BEGIN TO WIND DOWN WED AND SHOULD END WED NIGHT FROM W TO E AS SFC RIDGE PASSES AND WAA GETS UNDERWAY. THERE MAY BE SOME -SN THU/FRI DURING STRONG WAA. OPTED TO MAINTAIN PREVIOUS FCST OF LOW POPS ON THU FOR THIS POTENTIAL. CARRIED A DRY FCST FOR FRI...BUT WOULDN`T BE SURPRISED IF LOW POPS NEED TO BE ADDED IN LATER FCSTS AS WAA IS STILL STRONG. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... SNOW WILL CONTINUE OVERNIGHT AT BOTH SITES WITH MOSTLY MVFR CONDITIONS NOW AS THE SNOW PULLS OUT. WINDS ARE MORE NW NOW...SO UPSLOPE BECOMES LESS OF AN ISSUE AND DO NOT THINK IFR/LIFR WILL HAPPEN THAT LONG AT BOTH SITES TO INCLUDE IN THE TAFS. CONDITIONS WILL CONTINUE TO IMPROVE AFTER 12Z SAT AS LOW PRESSURE SYSTEM PRODUCING THE SNOW SHIFTS EAST OF THE AREA AND DRIER AIR STARTS TO MOVE IN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... NE GRADIENT TIGHTENS TONIGHT AS LOW PRESSURE TRACKS ACROSS LOWER MICHIGAN AND GEORGIAN BAY. IN GENERAL...NE WINDS TO 25 KT CAN BE EXPECTED WITH A FEW GUSTS TO 30 KNOTS...MOSTLY OVER SOUTHERN SECTIONS CLOSER TO THE TIGHTER GRADIENT. WEAK HIGH PRESSURE WILL LEAD TO WINDS BLO 25 KNOTS INTO SUN. A LOW PRESSURE SYSTEM TAKING SHAPE IN THE NORTHERN PLAINS WILL MOVE INTO THE UPPER GREAT LAKES ON MONDAY. NORTH TO NORTHWEST GALES REMAIN POSSIBLE BY TUE AS THE GRADIENT STRENGTHENS BETWEEN THE DEPARTING LOW AND STRONG HIGH PRESSURE BUILDING INTO THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY THIS EVENING MIZ012-013-014. && $$ SHORT TERM...JLA LONG TERM...ROLFSON AVIATION...GJM MARINE...JLA mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1141 AM CST SUN DEC 30 2007 .DISCUSSION.../ISSUED 400 AM CST SUN DEC 30 2007/ SOUTHERLY LOW LEVEL FLOW IN PROGRESS THIS MORNING ACROSS THE CWA WITH LOWER DEW POINT AIR AND DISSIPATING STATUS TO OUR SOUTHWEST. FORECAST THROUGH NEW YEARS DAY REMAINS ABOUT THE SAME BUT THE CHANCES FOR LIGHT SNOW JUST DON`T LOOK THAT GOOD UNTIL MONDAY NIGHT AND TUESDAY. CURRENTLY A VORT MAX IS LOCATED SOUTH OF LAKE WINNIPEG AND MOVING EASTWARD. SHORT WAVE TRAILING SOUTHWARD WILL MOVE ACROSS THE CWA THIS AFTERNOON AND EVENING. EXTENSIVE MID LEVEL CLOUDINESS EXISTS ACROSS THE EASTERN HALF OF THE DAKOTAS AND FAR WESTERN MN ATTM AND SHOULD PREVENT A DISASTER IN THE CLOUD COVER IF THE STATUS CONTINUES TO DISSIPATE THIS MORNING. RUC13 INSISTENT THAT THE STRATUS COULD BE OUT OF HERE BY NOON. BEST LAYER MOISTURE AND UPPER LEVEL Q-VECTOR CONVERGENCE IS POISED TO PASS ACROSS THE FAR NORTHERN AND EASTERN CWA THIS AFTERNOON AND EVENING. KEPT LOW CHANCE POPS IN THESE AREAS AND WENT DRY ELSEWHERE. KEPT THIS IDEA ALIVE THIS EVENING THEN INCREASED TO SMALL CHANCE POPS OVER ALL OF THE CWA DURING THE OVERNIGHT HOURS. MODELS REMAIN CONSISTENT ON KEEPING SEPARATE IDENTITIES TO LOW PRESSURE OF PACIFIC ORIGIN AND ONE FROM SOUTH CENTRAL CANADA AS THEY PASS ACROSS THE REGION MONDAY NIGHT. COUPLING OF THE TWO LOWS NOW INDICATED TO OCCUR A LITTLE FURTHER EAST AND OVER THE LOWER GREAT LAKES. FOR US...BEST CHANCES FOR SOME LIGHT SNOW APPEAR TO BE MONDAY NIGHT WITH COLD CYCLONIC FLOW AND SNOW SHOWERS FOR NEW YEARS DAY. STRONG HIGH PRESSURE STILL ON TRACK TO BE OVERHEAD ON WEDNESDAY ALONG WITH A GOOD AMOUNT OF SUNSHINE. COLD SPELL TO BE SHORT LIVED AS HEIGHTS ALOFT RISE SIGNIFICANTLY IN RESPONSE TO A DEEPENING EASTERN NORTH PACIFIC TROF. WARMING TREND PROGGED TO BEGIN THURSDAY AND PERHAPS LAST INTO TUESDAY OF NEXT WEEK. TEMPERATURES TRENDING WELL ABOVE NORMAL HEADING INTO NEXT WEEKEND...ESPECIALLY IF WE CAN STAY AWAY FROM THE STRATUS. && .AVIATION.../18Z TAF ISSUANCE/ TRICKY FORECAST THIS PERIOD. CURRENT IFR/LIFR CONDITIONS OVER EASTERN PARTS OF AREA INCLUDING KMSP/KRNH/KSTC/KEAU WILL CONTINUE THROUGH MOST OF THE PERIOD WITH THE SOUTHEAST LOW LEVEL FLOW. FARTHER WEST WHERE STRATUS BROKE OUT...WILL BE A LITTLE MORE PROBLEMATIC. VSBYS WILL LIKELY STAY IN THE 3 TO 5 SM RANGE BUT WITH THE POSSIBILITY OF STATUS BUILDING BACK TO THE WEST. OTHERWISE SOME IMPROVING CONDITIONS IN THE WEST...IN TERMS OF VSBY...MAY BE REALIZED LATE IN THE PERIOD...MONDAY MORNING AS TROUGH AND COOL FRONT APPROACH. WEAK UPPER TROUGH WITH SOME MID LEVEL INSTABILITY WILL CROSS THE AREA THIS AFTERNOON INTO THE EVENING WITH ISOLATED SNOW SHOWERS. CHANCES OF THESE SHOWERS AFFECTING THE TERMINAL SITES SLIM...BUT MOST LIKELY AREAS WOULD BE KSTC. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/JPR mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 523 AM CST SUN DEC 30 2007 .UPDATE...FOR 12Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 400 AM CST SUN DEC 30 2007/ SOUTHERLY LOW LEVEL FLOW IN PROGRESS THIS MORNING ACROSS THE CWA WITH LOWER DEW POINT AIR AND DISSIPATING STATUS TO OUR SOUTHWEST. FORECAST THROUGH NEW YEARS DAY REMAINS ABOUT THE SAME BUT THE CHANCES FOR LIGHT SNOW JUST DON`T LOOK THAT GOOD UNTIL MONDAY NIGHT AND TUESDAY. CURRENTLY A VORT MAX IS LOCATED SOUTH OF LAKE WINNIPEG AND MOVING EASTWARD. SHORT WAVE TRAILING SOUTHWARD WILL MOVE ACROSS THE CWA THIS AFTERNOON AND EVENING. EXTENSIVE MID LEVEL CLOUDINESS EXISTS ACROSS THE EASTERN HALF OF THE DAKOTAS AND FAR WESTERN MN ATTM AND SHOULD PREVENT A DISASTER IN THE CLOUD COVER IF THE STATUS CONTINUES TO DISSIPATE THIS MORNING. RUC13 INSISTENT THAT THE STRATUS COULD BE OUT OF HERE BY NOON. BEST LAYER MOISTURE AND UPPER LEVEL Q-VECTOR CONVERGENCE IS POISED TO PASS ACROSS THE FAR NORTHERN AND EASTERN CWA THIS AFTERNOON AND EVENING. KEPT LOW CHANCE POPS IN THESE AREAS AND WENT DRY ELSEWHERE. KEPT THIS IDEA ALIVE THIS EVENING THEN INCREASED TO SMALL CHANCE POPS OVER ALL OF THE CWA DURING THE OVERNIGHT HOURS. MODELS REMAIN CONSISTENT ON KEEPING SEPARATE IDENTITIES TO LOW PRESSURE OF PACIFIC ORIGIN AND ONE FROM SOUTH CENTRAL CANADA AS THEY PASS ACROSS THE REGION MONDAY NIGHT. COUPLING OF THE TWO LOWS NOW INDICATED TO OCCUR A LITTLE FURTHER EAST AND OVER THE LOWER GREAT LAKES. FOR US...BEST CHANCES FOR SOME LIGHT SNOW APPEAR TO BE MONDAY NIGHT WITH COLD CYCLONIC FLOW AND SNOW SHOWERS FOR NEW YEARS DAY. STRONG HIGH PRESSURE STILL ON TRACK TO BE OVERHEAD ON WEDNESDAY ALONG WITH A GOOD AMOUNT OF SUNSHINE. COLD SPELL TO BE SHORT LIVED AS HEIGHTS ALOFT RISE SIGNIFICANTLY IN RESPONSE TO A DEEPENING EASTERN NORTH PACIFIC TROF. WARMING TREND PROGGED TO BEGIN THURSDAY AND PERHAPS LAST INTO TUESDAY OF NEXT WEEK. TEMPERATURES TRENDING WELL ABOVE NORMAL HEADING INTO NEXT WEEKEND...ESPECIALLY IF WE CAN STAY AWAY FROM THE STRATUS. && .AVIATION.../12Z TAF ISSUANCE/ CEILINGS CONTINUE TO IMPROVE ACROSS WEST CENTRAL MN THIS MORNING...WITH VFR CEILINGS /CIRCA 10K FEET/ AT KAXN/KRWF AT 12Z. LOW LEVEL RH PROGS INDICATE THAT HIGHER CEILINGS WILL CONTINUE WORKING INTO CENTRAL MN THIS MORNING...SO HAVE INCLUDED A PERIOD OF BKN MVFR OR VFR AT KMSP AND KSTC. MVFR VISIBIILITIES SHOULD ALSO IMPROVE TO VFR BY MID TO LATE MORNING. SCATTERED FLURRIES ARE ALSO POSSIBLE TODAY...MAINLY AT KSTC/KRNH/KEAU. SNOW CHANCES INCREASE TONIGHT INTO MONDAY...AS A DISTURBANCE DROPS SOUTH/EAST FROM CANADA. CEILINGS WILL LIKELY DEGRADE BACK INTO THE MVFR CATEGORY TONIGHT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/LS mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 400 AM CST SUN DEC 30 2007 .DISCUSSION... SOUTHERLY LOW LEVEL FLOW IN PROGRESS THIS MORNING ACROSS THE CWA WITH LOWER DEW POINT AIR AND DISSIPATING STATUS TO OUR SOUTHWEST. FORECAST THROUGH NEW YEARS DAY REMAINS ABOUT THE SAME BUT THE CHANCES FOR LIGHT SNOW JUST DON`T LOOK THAT GOOD UNTIL MONDAY NIGHT AND TUESDAY. CURRENTLY A VORT MAX IS LOCATED SOUTH OF LAKE WINNIPEG AND MOVING EASTWARD. SHORT WAVE TRAILING SOUTHWARD WILL MOVE ACROSS THE CWA THIS AFTERNOON AND EVENING. EXTENSIVE MID LEVEL CLOUDINESS EXISTS ACROSS THE EASTERN HALF OF THE DAKOTAS AND FAR WESTERN MN ATTM AND SHOULD PREVENT A DISASTER IN THE CLOUD COVER IF THE STATUS CONTINUES TO DISSIPATE THIS MORNING. RUC13 INSISTENT THAT THE STRATUS COULD BE OUT OF HERE BY NOON. BEST LAYER MOISTURE AND UPPER LEVEL Q-VECTOR CONVERGENCE IS POISED TO PASS ACROSS THE FAR NORTHERN AND EASTERN CWA THIS AFTERNOON AND EVENING. KEPT LOW CHANCE POPS IN THESE AREAS AND WENT DRY ELSEWHERE. KEPT THIS IDEA ALIVE THIS EVENING THEN INCREASED TO SMALL CHANCE POPS OVER ALL OF THE CWA DURING THE OVERNIGHT HOURS. MODELS REMAIN CONSISTENT ON KEEPING SEPARATE IDENTITIES TO LOW PRESSURE OF PACIFIC ORIGIN AND ONE FROM SOUTH CENTRAL CANADA AS THEY PASS ACROSS THE REGION MONDAY NIGHT. COUPLING OF THE TWO LOWS NOW INDICATED TO OCCUR A LITTLE FURTHER EAST AND OVER THE LOWER GREAT LAKES. FOR US...BEST CHANCES FOR SOME LIGHT SNOW APPEAR TO BE MONDAY NIGHT WITH COLD CYCLONIC FLOW AND SNOW SHOWERS FOR NEW YEARS DAY. STRONG HIGH PRESSURE STILL ON TRACK TO BE OVERHEAD ON WEDNESDAY ALONG WITH A GOOD AMOUNT OF SUNSHINE. COLD SPELL TO BE SHORT LIVED AS HEIGHTS ALOFT RISE SIGNIFICANTLY IN RESPONSE TO A DEEPENING EASTERN NORTH PACIFIC TROF. WARMING TREND PROGGED TO BEGIN THURSDAY AND PERHAPS LAST INTO TUESDAY OF NEXT WEEK. TEMPERATURES TRENDING WELL ABOVE NORMAL HEADING INTO NEXT WEEKEND...ESPECIALLY IF WE CAN STAY AWAY FROM THE STRATUS. && .AVIATION.../06Z TAF ISSUANCE/ MID CLDS MVG ACRS LWR CLD DECK IN W MN HV KEPT CIGS AND VSBYS FM TANKING. CONCERN MAINLY AT RWF IS THAT AS CLDS THIN THAT LOW STRATUS AND FOG WL QUICKLY DVLP. WITH LOW LVL FLOW STILL WEAK AND WAA GRADU STRENGTHENING INVERSON THRU TMRW WILL BE TUF TO BRK UP CLDS. WL INTRO BRKS ONLY AT RWF AND AXN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/BAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DULUTH MN 322 AM CST SUN DEC 30 2007 .SHORT TERM...TODAY THROUGH MONDAY DESPITE NO MAJOR STORMS..THE FORECAST IS RATHER COMPLICATED FORECAST FOR THE FIRST 36 HOURS OF THIS CYCLE WITH SEVERAL LOW- AMPLITUDE DISTURBANCES TO AFFECT THE DLH CWA. FIRST ITEM OF CONCERN IS THE WNW-ESE ORIENTED BAND OF LIGHT SNOW THAT HAS BEEN SLOWLY TRANSLATING NEWD ACROSS NE MN AND WRN LK SUPERIOR FOR THE LAST 18 HOURS. RADAR RETURNS FROM KDLH HAVE DIMINISHED SOMEWHAT IN THE PAST HOUR..BUT STRONGLY SUSPECT THAT THIS IS DUE TO SAMPLING CONSIDERATIONS AS THE FORCING FOR THIS BAND OF SNOW APPEARS TO BE TIED TO WARM ADVECTION AND FRONTOGENESIS IN A RATHER SHALLOW LAYER WITHIN ABOUT 6 KFT AGL. AS THE BAND CONTINUES TO MOVE NEWD..THE BEAM IS LIKELY OVERSHOOTING MOST OF THE ECHOES. THE NAM/RUC SEEM TO PICK UP ON THIS MESOSCALE FEATURE RATHER WELL IN THE MASS FIELDS..AND BOTH LINGER DECENT FORCING OVER THE MN ARROWHEAD THRU ABOUT MIDDAY..SO HAVE KEPT LIKELY POPS FOR UP TO AN INCH OR SO OF ACCUM IN THIS AREA. NORTH SHORE TERRAIN RIDGE WILL ALSO EXPERIENCE A PERIOD OF SE FLOW THIS AFTERNOON/EVENING WHICH MAY ACT TO LOCALLY ENHANCE SNOW IN FAVORED AREAS. NEXT ISSUE IS THE COMPACT VORT MAX CLEARLY EVIDENT IN WV SAT IMAGERY OVER FAR NE ND. THIS VORT MAX IS PROGGED TO TRANSLATE EWD TODAY/TONIGHT ALONG THE CANADIAN BORDER..AND EXPECT LIGHT SNOW TO CONTINUE TO EXPAND IN COVERAGE /PER CURRENT OBS FROM KMVX RADAR/ ACROSS NRN MN AS THIS IMPULSE INTERACTS WITH NWD RETREATING BAROCLINIC ZONE. ALL SAID..AN INCH OR TWO OF SNOW APPEARS POSSIBLE BY MONDAY MORNING. FINALLY..STRONGER MID/UPPER LEVEL CIRCULATION WILL DROP SEWD FROM MANITOBA ON MONDAY..AND SHUD SPREAD ANOTHER ROUND OF LIGHT SNOW ACROSS MUCH OF NRN MN AND NW WI BEGINNING MONDAY AFTERNOON. HAVE ALSO MADE SOME ADJUSTMENTS TO TEMPS TO REFLECT A SMALLER DROP OVERNIGHT TONIGHT AS CLOUDS PERSIST..WITH WINDS FINALLY SHIFTING TO THE W/NW OUT WEST MONDAY AFTERNOON WHICH SHUD ALLOW SOME COLDER AIR TO FILTER IN. CANNOT RULE OUT SOME LIGHT SNOW OR FREEZING DRIZZLE ACROSS SRN SECTIONS OF THE DLH CWA..BUT CONFIDENCE IN MEASURABLE PRECIP IN THIS AREA IS VERY LOW ATTM..SO HAVE CONFINED BEST POPS/QPF/SNOW ACCUMS ACROSS THE NE HALF OF THE CWA THRU TOMORROW. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY GOOD MODEL AGMT ON STRONG UPR LVL S/WV TROF SWINGING ACRS MN/WI MON NGT/TUE. SPEED OF SYSTEM AND LACK OF MSTR WILL LIMIT ACCUMS. NW WINDS ON BACK SIDE OF SFC SYSTEM WILL SET UP LES REGIME ALG S SHORE SNOW BELT FOR TUE/WED. ACCUMS MAY REACH ADVY CRITERIA. DRY PERIOD SETS UP FOR THU/FRI AS SFC RIDGE MOVES ACRS THE REGION. SLY WINDS ON BACK SIDE OF RIDGE WILL BRING WAA/ISENT LIFT AND GRADUALLY MOISTEN THE AIRMASS OVR THE REGION. WITH APPROACH OF S/WV IN SWLY FLOW ALOFT...EXPECT PRECIP BY EARLY SAT. WITH STRONG 850 MB WAA...MIXED PRECIP SEEMS LIKELY WITH SOME FZ PRECIP PSBL DEPENDING ON HOW FAST SFC TEMPS INCRS. FOR NOW WILL STAY WITH A RA/SN MIX. && .AVIATION... EXTENSIVE IFR/MVFR CLD DECK WILL PERSIST THRU TAF PF DUE TO MSTR TRAPPED BLO LOLVL TEMP INVERSION. OCNL -SN OR FLURRIES WILL CONT ASSOC WITH WEAK LOLVL CONVERGENCE. ISOLD -FZDZ ALSO PSBL THRU THE MRNG HRS. VSBYS SHUD BE VFR EXCEPT OCNLY MVFR IN -SN. && POINT TEMPS/POPS... DLH 22 19 20 4 / 30 40 40 40 INL 21 14 19 0 / 40 40 40 30 BRD 23 14 19 4 / 20 30 30 30 HYR 23 20 25 5 / 20 30 40 40 ASX 24 21 28 10 / 30 40 40 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...NONE. $$ MILLER/04 mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 430 AM CST SUN DEC 30 2007 .DISCUSSION... H500 LONGWAVE TROF WILL DOMINATE THE CONUS UNTIL MONDAY WHEN IT WILL THEN PROPAGATE TO THE ERN CONUS BY TUESDAY...PLACING THE FA IN NWLY MID LEVEL FLOW. A H500 LONGWAVE RIDGE WILL THEN COME TO DOMINATE THE CONUS DURING MID TO LATE WEEK. THIS WILL OVERALL SIGNAL AN END TO THE RATHER ACTIVE PATTERN THAT WE HAVE EXPERIENCED LATELY...WITH THE RESULT BEING SYSTEMS BEING SPACED MORE APART FROM EACH OTHER. HOWEVER THRU MONDAY...LOOK FOR SEVERAL SYSTEMS TO IMPACT THE AREA...OR AT LEAST ATTEMPT TO. SYSTEM NUMBER ONE IS A WEAK SHORTWAVE TROF JUST W OF THE FA ATTM AND WILL PUSH THRU THE AREA TODAY. SYSTEM OVERALL IS MOISTURE LACKING...ESPECIALLY IN THE LOWER LEVELS. MAIN IMPACT FROM THIS WILL BE A DECK OF MID CLOUDS THAT WILL PUSH OFF TO THE E THIS MORNING WITH NO PCPN EXPECTED...ALTHOUGH A STRAY FLURRY OR TWO IS NOT TOTALLY OUT OF THE QUESTION FOR AREAS S AND E OF KSTL EARLY THIS MORNING. LOOK FOR TEMPERATURES TO BE A BIT MILDER THAN YESTERDAY...AND DID NOT HAVE A PROBLEM WITH MOS TEMPS...ALTHOUGH TRIMMED A DEG OR TWO IN THE NWRN FA FOR SNOW PACK THAT STILL EXISTS THERE. SYSTEM NUMBER TWO IS ANOTHER SHORTWAVE TROF THAT WILL SWING THRU THE NRN FA AT FIRST LATE TONIGHT AND MONDAY MORNING...BUT THEN DROP SEWD THRU THE FA DURING THE REMAINDER OF THE DAY ON MONDAY. THIS WILL ALSO BE ACCOMPANIED BY A STRONG SFC CDFNT. LIKE SYSTEM NUMBER ONE...THIS ONE WILL ALSO BE RATHER MOISTURE CHALLENGED WITH PWATS COMPARABLE TO THE OTHER SYSTEM OF JUST SLIGHTLY ABOVE SEASONAL NORMALS. FORCING WILL BE STRONGER WITH THIS SYSTEM HOWEVER...AND IS STILL WORTHY OF A LOW CHANCE POP AT THIS TIME. CONFINED THE BETTER PCPN PROBS TO THE NRN FA WHERE THE DEEPER MOISTURE WILL BE AND LESS LOWER LEVEL DRY AIR TO OVERCOME. REDUCED POPS ELSEWHERE TO SLIGHT CHANCE...BUT ALSO HAVE SPRINKLES/FLURRIES IN AS WELL TO ACCOUNT FOR VERY LIGHT PCPN POTENTIAL WHICH IS MORE LIKELY OUTCOME AT THIS TIME. WITH DEEP CYCLONIC FLOW AND ADDITIONAL WEAKER DISTURBANCES MOVING SEWD THRU THE AREA ON MONDAY NIGHT AND NEW YEARS DAY...HAVE MAINTAINED FLURRIES FOR THESE PERIODS. MUCH COLDER AIR WILL BEGIN TO BE USHERED IN LATE IN THE DAY ON MONDAY AND CONTINUE THRU NEW YEARS DAY...WITH BLUSTERY CONDITIONS EXPECTED WITH WIND GUSTS TO 35 MPH. THIS WILL BE THE COLDEST AIR OF THE SEASON...AS A 1045MB HI PRES SETTLES INTO THE AREA...WITH SINGLE DIGIT LOWS LIKELY ON WEDNESDAY MORNING FOR A DECENT PORTION OF THE AREA. THIS HI PRES WILL THEN DOMINATE THE AREA THRU LATE WEEK WITH DRY WX...ALTHOUGH TEMPS WILL MODERATE HEADING INTO THE WEEKEND. TES && .AVIATION... FOR THE 06Z TAFS...LTL AVIATION CONCERNS THIS FCST PD...WITH VFR CONDITIONS AND NO PCPN EXPECTED. LATEST SATELLITE LOOP DOES SHOW A LARGE AREA OF LOW LVL CLOUDS OVR ERN KS BUT IT ARS THAT THIS CLOUD CVR WILL LIKELY REMAIN NW OF THE TAF SITES AND MAY GRADUALLY DISSIPATE AS IT GETS FURTHER E INTO NWRN MO. WITH APPROACH OF SWLY FLOW SHRTWV TROF SHOULD SEE AN INCRS IN MID LVL CLOUDS LT TGT...ESPECIALLY IN STL/SUS. LATEST RUC ANLYS OF RH HAS A BAND OF MOISTURE AT 700MB AND 5000 MB EXTDG NE TO THE STL AREA BY 09Z SUN. MDL TIME SECTIONS FOR STL SHOW 80-90 PERCENT RH VALUES FM 06Z TO 12Z SUN ARND THE 500 MB LVL. ON SUN THERE MAY BE ENOUGH LOW LVL MOISTURE FOR SCT DIURNAL CUMULUS CLOUDS WITH A MID-HI LVL CLOUD CEILING CONTG OVR MUCH OF THE CWA. LGT S-SELY SFC WNDS CAN BE EXPECTED LT TGT ON THE WEST SIDE OF SFC RDG PUSHING E OF THE CWA. S-SELY SFC WNDS SUN MRNG WILL BCM SWLY SUN AFTN INCRSG TO 8-10 KTS. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 1108 PM CST SAT DEC 29 2007 .UPDATE... FORECAST UPDATED FOR TEMPERATURES AND SKY COVER TONIGHT. SATELLITE TRENDS AND MODEL PROGS SUGGEST THAT SERN HALF OF THE CWA WILL BECOME MOSTLY CLOUDY. TEMPERATURES FELL QUICKLY EARLY IN THE EVENING TO NEAR FORECAST LOWS...BUT HAVE STEADIED OR ROSE A FEW DEGREES IN SOME AREAS. THINK THIS WILL CONTINUE TO BE THE CASE.. ESPEICALLY WHERE CLOUD COVER WILL INCREASE OVERNIGHT. BRITT && .DISCUSSION... SFC RIDGE CONTINUES TO SLOWLY MOVE OFF TO THE EAST TODAY...SO BEGINNING TO SEE SOUTHWESTERLY WINDS RETURN OVER WESTERN MISSOURI. CLOUDS CLEARED OUT QUICKLY TODAY...GIVING WAY TO LOTS OF SUNSHINE. THIS HELPED TEMPS WARM UP INTO THE MID 30S TO LOW 40S...DESPITE THE SNOW COVER OVER THE NORTHERN THIRD OF THE CWA. FOR TONIGHT...THE SFC RIDGE WILL MOVE FURTHER AWAY AS NEXT UPPER LEVEL SHORTWAVE APPROACHES THE AREA LATE TONIGHT AND EARLY SUNDAY MORNING. HOWEVER...LACK OF LOW LEVEL MOISTURE WILL MAKE PASSAGE OF THE SHORTWAVE A DRY ONE...THOUGH WILL SEE AN INCREASE IN MID AND HIGH CLOUDS...WITH LOWS IN THE 20S. DESPITE SOME WEAK CAA WITH THIS SHORTWAVE...MILD CONDITIONS WILL PREVAIL OVER THE AREA ON SUNDAY WITH TEMPERATURES IN THE UPPER 30S NORTH TO UPPER 40S SOUTH. HOWEVER...NEXT SHORTWAVE TO APPROACH THE AREA MONDAY. THIS SYSTEM IS A MUCH MORE ROBUST THAN PREVIOUS SYSTEM. STRONGEST ENERGY TO REMAIN JUST NORTH OF CWA...SO WILL KEEP LOW CHANCE MENTION FOR FAR EASTERN SECTIONS OF CWA...MAINLY ALONG AND EAST OF MISSISSIPPI RIVER...WITH SLIGHT CHANCE POPS FOR REST OF CWA. WILL SEE A MIX OF SNOW AND RAIN ALONG THE I-70 CORRIDOR...WITH ALL SNOW FURTHER NORTH AND RAIN TO THE SOUTH DURING THE DAY ON MONDAY...THEN CHANGE TO ALL SNOW/ FLURRIES FOR NEW YEARS EVE. FOR NEW YEARS DAY...WILL SEE LINGERING FLURRY ACTIVITY UNDER PARTLY TO MOSTLY CLOUDY SKIES. TEMPERATURES WILL STRUGGLE TO RISE INTO THE LOW 20S FAR NORTH TO AROUND 30 FAR SOUTH AS DEEP RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION. TUESDAY NIGHT WILL BE ONE OF THE COLDEST SO FAR THIS SEASON WITH LOWS AROUND 5 DEGREES ABOVE FAR NORTH TO AROUND 14 DEGREES FAR SOUTH. BEYOND THAT SFC RIDGE TO SLOWLY SLIDE OFF TO THE SOUTHEAST...WITH A GRADUAL WARM UP TOWARDS NEXT WEEKEND. NEXT SYSTEM TO AFFECT THE AREA LATE FRIDAY NIGHT AND SATURDAY. BYRD && .AVIATION... FOR THE 06Z TAFS...LTL AVIATION CONCERNS THIS FCST PD...WITH VFR CONDITIONS AND NO PCPN EXPECTED. LATEST SATELLITE LOOP DOES SHOW A LARGE AREA OF LOW LVL CLOUDS OVR ERN KS BUT IT ARS THAT THIS CLOUD CVR WILL LIKELY REMAIN NW OF THE TAF SITES AND MAY GRADUALLY DISSIPATE AS IT GETS FURTHER E INTO NWRN MO. WITH APPROACH OF SWLY FLOW SHRTWV TROF SHOULD SEE AN INCRS IN MID LVL CLOUDS LT TGT...ESPECIALLY IN STL/SUS. LATEST RUC ANLYS OF RH HAS A BAND OF MOISTURE AT 700MB AND 5000 MB EXTDG NE TO THE STL AREA BY 09Z SUN. MDL TIME SECTIONS FOR STL SHOW 80-90 PERCENT RH VALUES FM 06Z TO 12Z SUN ARND THE 500 MB LVL. ON SUN THERE MAY BE ENOUGH LOW LVL MOISTURE FOR SCT DIURNAL CUMULUS CLOUDS WITH A MID-HI LVL CLOUD CEILING CONTG OVR MUCH OF THE CWA. LGT S-SELY SFC WNDS CAN BE EXPECTED LT TGT ON THE WEST SIDE OF SFC RDG PUSHING E OF THE CWA. S-SELY SFC WNDS SUN MRNG WILL BCM SWLY SUN AFTN INCRSG TO 8-10 KTS. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 507 PM CST SAT DEC 29 2007 .DISCUSSION... SFC RIDGE CONTINUES TO SLOWLY MOVE OFF TO THE EAST TODAY...SO BEGINNING TO SEE SOUTHWESTERLY WINDS RETURN OVER WESTERN MISSOURI. CLOUDS CLEARED OUT QUICKLY TODAY...GIVING WAY TO LOTS OF SUNSHINE. THIS HELPED TEMPS WARM UP INTO THE MID 30S TO LOW 40S...DESPITE THE SNOW COVER OVER THE NORTHERN THIRD OF THE CWA. FOR TONIGHT...THE SFC RIDGE WILL MOVE FURTHER AWAY AS NEXT UPPER LEVEL SHORTWAVE APPROACHES THE AREA LATE TONIGHT AND EARLY SUNDAY MORNING. HOWEVER...LACK OF LOW LEVEL MOISTURE WILL MAKE PASSAGE OF THE SHORTWAVE A DRY ONE...THOUGH WILL SEE AN INCREASE IN MID AND HIGH CLOUDS...WITH LOWS IN THE 20S. DESPITE SOME WEAK CAA WITH THIS SHORTWAVE...MILD CONDITIONS WILL PREVAIL OVER THE AREA ON SUNDAY WITH TEMPERATURES IN THE UPPER 30S NORTH TO UPPER 40S SOUTH. HOWEVER...NEXT SHORTWAVE TO APPROACH THE AREA MONDAY. THIS SYSTEM IS A MUCH MORE ROBUST THAN PREVIOUS SYSTEM. STRONGEST ENERGY TO REMAIN JUST NORTH OF CWA...SO WILL KEEP LOW CHANCE MENTION FOR FAR EASTERN SECTIONS OF CWA...MAINLY ALONG AND EAST OF MISSISSIPPI RIVER...WITH SLIGHT CHANCE POPS FOR REST OF CWA. WILL SEE A MIX OF SNOW AND RAIN ALONG THE I-70 CORRIDOR...WITH ALL SNOW FURTHER NORTH AND RAIN TO THE SOUTH DURING THE DAY ON MONDAY...THEN CHANGE TO ALL SNOW/ FLURRIES FOR NEW YEARS EVE. FOR NEW YEARS DAY...WILL SEE LINGERING FLURRY ACTIVITY UNDER PARTLY TO MOSTLY CLOUDY SKIES. TEMPERATURES WILL STRUGGLE TO RISE INTO THE LOW 20S FAR NORTH TO AROUND 30 FAR SOUTH AS DEEP RIDGE OF HIGH PRESSURE BUILDS INTO THE REGION. TUESDAY NIGHT WILL BE ONE OF THE COLDEST SO FAR THIS SEASON WITH LOWS AROUND 5 DEGREES ABOVE FAR NORTH TO AROUND 14 DEGREES FAR SOUTH. BEYOND THAT SFC RIDGE TO SLOWLY SLIDE OFF TO THE SOUTHEAST...WITH A GRADUAL WARM UP TOWARDS NEXT WEEKEND. NEXT SYSTEM TO AFFECT THE AREA LATE FRIDAY NIGHT AND SATURDAY. BYRD && .AVIATION... FOR THE 00Z TAFS...LTL AVIATION CONCERNS THIS FCST PD...WITH VFR CONDITIONS AND NO PCPN EXPECTED. WITH APPROACH OF SWLY FLOW SHRTWV TROF SHOULD SEE AN INCRS IN MID LVL CLOUDS LT TGT...ESPECIALLY IN STL/SUS. LATEST RUC ANLYS OF RH HAS A BAND OF MOISTURE AT 700MB AND 5000 MB EXTDG NE TO THE STL AREA BY 09Z SUN. MDL TIME SECTIONS FOR STL SHOW 80-90 PERCENT RH VALUES FM 06Z TO 12Z SUN ARND THE 500 MB LVL. ON SUN THERE MAY BE ENOUGH LOW LVL MOISTURE FOR SCT DIURNAL CUMULUS CLOUDS WITH A MID-HI LVL CLOUD CEILING CONTG OVR MUCH OF THE CWA. LGT S-SELY SFC WNDS CAN BE EXPECTED TGT ON THE WEST SIDE OF SFC RDG PUSHING E OF THE CWA. S-SELY SFC WNDS SUN MRNG WILL BCM SWLY SUN AFTN INCRSG TO 8-10 KTS. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1116 AM CST SAT DEC 29 2007 .UPDATE... QUICK UPDATE TO THE FORECAST FORTHCOMING TO ACCOUNT FOR HOURLY TEMP AND DEWPOINT TRENDS AS WELL AS TO TWEAK HIGHS DOWNWARD A FEW DEGREES...ESPECIALLY ACROSS SOUTH CENTRAL MO. NARROW BAND OF STRATUS HAS DISSIPATED AS EXPECTED DUE TO MIXING. WARM ADVECTION IS UNDERWAY...BUT LAGGING IN TIME A BIT. USING 12Z SOUNDINGS AND EXPECTED 925/850MB TEMPS...HAVE TRENDED EXPECTED HIGHS DOWNWARD A FEW DEGREES. OTHERWISE...GOING FORECAST LOOKS GOOD. GAGAN/CLAYCOMB && .DISCUSSION... SURFACE HIGH PRESSURE WAS SHIFTING ACROSS THE REGION THIS MORNING IN THE WAKE OF THIS MORNINGS UPPER LOW THAT FORCED SOME LIGHT RAIN AND SNOW IN MOST AREAS. SOME LINGERING STRATUS WAS LIMITING TEMPERATURES FROM FALLING INTO THE TEENS ALONG THE OZARK PLATEAU. THIS STRATUS WILL LIKELY BURN OFF QUICKLY UPON SUNRISE THIS MORNING. MEANWHILE...ANOTHER UPPER DISTURBANCE WILL APPROACH FROM THE WEST LATE TONIGHT. A MOISTURE STARVED ATMOSPHERE WILL KEEP CONDITIONS DRY THROUGH THE PASSAGE OF THIS SYSTEM. HOWEVER...I CAN NOT RULE OUT SOME PRECIP CHANCES FOR MONDAY AS A SURGE OF ARCTIC AIR RUSHES INTO THE REGION. THIS CHANGE IN AIRMASS WAS THE MAIN FORECAST CHALLENGE IN THIS MORNINGS ANALYSIS AS SINGLE DIGIT READINGS WILL BE POSSIBLE BY MID WEEK. SHORT TERM (TODAY - TUESDAY NIGHT)... RUC 275K POTENTIAL TEMPERATURE SURFACE EXPLAINS WHY STRATUS IS LINGERING ALONG AND SOUTH OF THE I-44 CORRIDOR. A TROUGH AXIS APPEARS TO BE STATIONARY NEAR THIS CORRIDOR...AND WEAK FLOW ACROSS THE AXIS IS PROVIDING A WEAK BAND OF LIFT IN THE FORM OF PRESSURE ADVECTION. AFTER SUNRISE...THE LOWER TROP WILL BEGIN TO MIX OUT WHICH WILL LIKELY DISSIPATE THIS LOW LEVEL ZONE OF COLDER AIR. UNDER MOSTLY SUNNY SKIES ALONG WITH A RETURN OF SOUTHERLY WINDS...TEMPERATURES WILL WARM INTO THE 40S THIS AFTERNOON. A SHORTWAVE TROUGH WILL APPROACH THE REGION LATE TONIGHT. DESPITE MODERATE FORCING IN ADVANCE OF THIS WAVE...PRESSURE CONDENSATION LEVELS ARE SO HIGH AND CAN NOT BE REALIZED DUE TO A VERY DRY AIRMASS. 00Z SOUNDINGS ACROSS THE CENTRAL AND SOUTHERN PLAINS MEASURED PWATS LESS THAN ONE QUARTER OF AN INCH. THEREFORE ONLY SOME MID AND UPPER LEVEL CLOUDS WILL RESULT FROM THE PASSAGE OF THIS DISTURBANCE. SOUTHERLY WINDS AT THE SURFACE AND CLEAR SKIES WILL BOOST TEMPERATURES UP A FEW MORE DEGREES FROM TODAYS EXPECTED READINGS. AS A MATTER OF FACT...I INCREASED TEMPERATURES IN MOST LOCATIONS A FEW DEGREES WARMER THAN MAV GUIDANCE. PROGGED SURFACE TO 850 THICKNESSES CORRELATES WITH TEMPERATURES APPROACHING THE LOWER 50S ON SUNDAY. AGAIN...NO PRECIPITATION IS EXPECTED THROUGH THE REST OF THE WEEKEND. ALL MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT AND SHOW GOOD RUN TO RUN CONSISTENCY WITH A SURGE OF ARCTIC AIR DURING THE DAY ON MONDAY. TEMPERATURES AT THIS POINT WILL EXPERIENCE A COOLING TREND THROUGH WEDNESDAY. LOWER TEENS OR SINGLE DIGIT READINGS CAN NOT BE RULED OUT TUESDAY NIGHT INTO WEDNESDAY MORNING...AS THE COLDEST AREA OF THIS AIRMASS SPREADS DIRECTLY OVER THE EASTERN PLAINS AND OZARKS REGION. I INSERTED SOME SMALL POPS FOR MONDAYS DAY PERIOD. IT APPEARS AS THOUGH THERE WILL BE SOME UPPER SUPPORT CREATING LIFT AS THE ARCTIC SURGE OCCURS. MODELS SUGGEST A LOT OF DRY AIR ABOVE 500MB...HOWEVER...SUFFICIENT SHALLOW MOISTURE WILL EXIST FOR SLIGHT CHANCES OF LIGHT SNOW OR RAIN. LONG TERM (WEDNESDAY - FRIDAY)... FLOW OVER MOST OF THE NATIONS MID SECTION DURING THE LONG TERM WILL BE MOSTLY ZONAL AS A LONG WAVE RIDGE BEGINS TO DEAMPLIFY AS IT PROGRESSES OVERHEAD. THIS PATTERN SHOULD RESULT IN ABOVE NORMAL TEMPERATURES AND LITTLE TO NO RAIN CHANCES. DESPITE A GOOD POSSIBILITY OF SOUTHERLY FLOW...THE SURFACE PRESSURE PATTERN ACROSS THE GULF COAST STATES IS CONDUCIVE FOR OFF SHORE FLOW...ULTIMATELY SHUTTING DOWN ANY POSSIBLE MOISTURE RETURN. CRAMER && .AVIATION... FOR THE 18Z TAF PACKAGE...VFR CONDITIONS ARE EXPECTED FOR THE NEXT 24 HOURS AND BEYOND. ANOTHER FAST MOVING DISTURBANCE WILL SLIDE THROUGH THE REGION TONIGHT BRINGING WITH IT MAINLY MID AND HIGH LEVEL CLOUD COVER. WINDS WILL REMAIN OUT OF THE SOUTH. GAGAN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 535 AM CST SAT DEC 29 2007 ...UPDATE TO AVIATION... .DISCUSSION... SURFACE HIGH PRESSURE WAS SHIFTING ACROSS THE REGION THIS MORNING IN THE WAKE OF THIS MORNINGS UPPER LOW THAT FORCED SOME LIGHT RAIN AND SNOW IN MOST AREAS. SOME LINGERING STRATUS WAS LIMITING TEMPERATURES FROM FALLING INTO THE TEENS ALONG THE OZARK PLATEAU. THIS STRATUS WILL LIKELY BURN OFF QUICKLY UPON SUNRISE THIS MORNING. MEANWHILE...ANOTHER UPPER DISTURBANCE WILL APPROACH FROM THE WEST LATE TONIGHT. A MOISTURE STARVED ATMOSPHERE WILL KEEP CONDITIONS DRY THROUGH THE PASSAGE OF THIS SYSTEM. HOWEVER...I CAN NOT RULE OUT SOME PRECIP CHANCES FOR MONDAY AS A SURGE OF ARCTIC AIR RUSHES INTO THE REGION. THIS CHANGE IN AIRMASS WAS THE MAIN FORECAST CHALLENGE IN THIS MORNINGS ANALYSIS AS SINGLE DIGIT READINGS WILL BE POSSIBLE BY MID WEEK. SHORT TERM (TODAY - TUESDAY NIGHT)... RUC 275K POTENTIAL TEMPERATURE SURFACE EXPLAINS WHY STRATUS IS LINGERING ALONG AND SOUTH OF THE I-44 CORRIDOR. A TROUGH AXIS APPEARS TO BE STATIONARY NEAR THIS CORRIDOR...AND WEAK FLOW ACROSS THE AXIS IS PROVIDING A WEAK BAND OF LIFT IN THE FORM OF PRESSURE ADVECTION. AFTER SUNRISE...THE LOWER TROP WILL BEGIN TO MIX OUT WHICH WILL LIKELY DISSIPATE THIS LOW LEVEL ZONE OF COLDER AIR. UNDER MOSTLY SUNNY SKIES ALONG WITH A RETURN OF SOUTHERLY WINDS...TEMPERATURES WILL WARM INTO THE 40S THIS AFTERNOON. A SHORTWAVE TROUGH WILL APPROACH THE REGION LATE TONIGHT. DESPITE MODERATE FORCING IN ADVANCE OF THIS WAVE...PRESSURE CONDENSATION LEVELS ARE SO HIGH AND CAN NOT BE REALIZED DUE TO A VERY DRY AIRMASS. 00Z SOUNDINGS ACROSS THE CENTRAL AND SOUTHERN PLAINS MEASURED PWATS LESS THAN ONE QUARTER OF AN INCH. THEREFORE ONLY SOME MID AND UPPER LEVEL CLOUDS WILL RESULT FROM THE PASSAGE OF THIS DISTURBANCE. SOUTHERLY WINDS AT THE SURFACE AND CLEAR SKIES WILL BOOST TEMPERATURES UP A FEW MORE DEGREES FROM TODAYS EXPECTED READINGS. AS A MATTER OF FACT...I INCREASED TEMPERATURES IN MOST LOCATIONS A FEW DEGREES WARMER THAN MAV GUIDANCE. PROGGED SURFACE TO 850 THICKNESSES CORRELATES WITH TEMPERATURES APPROACHING THE LOWER 50S ON SUNDAY. AGAIN...NO PRECIPITATION IS EXPECTED THROUGH THE REST OF THE WEEKEND. ALL MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT AND SHOW GOOD RUN TO RUN CONSISTENCY WITH A SURGE OF ARCTIC AIR DURING THE DAY ON MONDAY. TEMPERATURES AT THIS POINT WILL EXPERIENCE A COOLING TREND THROUGH WEDNESDAY. LOWER TEENS OR SINGLE DIGIT READINGS CAN NOT BE RULED OUT TUESDAY NIGHT INTO WEDNESDAY MORNING...AS THE COLDEST AREA OF THIS AIRMASS SPREADS DIRECTLY OVER THE EASTERN PLAINS AND OZARKS REGION. I INSERTED SOME SMALL POPS FOR MONDAYS DAY PERIOD. IT APPEARS AS THOUGH THERE WILL BE SOME UPPER SUPPORT CREATING LIFT AS THE ARCTIC SURGE OCCURS. MODELS SUGGEST A LOT OF DRY AIR ABOVE 500MB...HOWEVER...SUFFICIENT SHALLOW MOISTURE WILL EXIST FOR SLIGHT CHANCES OF LIGHT SNOW OR RAIN. LONG TERM (WEDNESDAY - FRIDAY)... FLOW OVER MOST OF THE NATIONS MID SECTION DURING THE LONG TERM WILL BE MOSTLY ZONAL AS A LONG WAVE RIDGE BEGINS TO DEAMPLIFY AS IT PROGRESSES OVERHEAD. THIS PATTERN SHOULD RESULT IN ABOVE NORMAL TEMPERATURES AND LITTLE TO NO RAIN CHANCES. DESPITE A GOOD POSSIBILITY OF SOUTHERLY FLOW...THE SURFACE PRESSURE PATTERN ACROSS THE GULF COAST STATES IS CONDUCIVE FOR OFF SHORE FLOW...ULTIMATELY SHUTTING DOWN ANY POSSIBLE MOISTURE RETURN. CRAMER && .AVIATION... FOR THE 1200 UTC KSGF/KJLN TAFS...MVFR STRATUS IS STILL ONGOING OVER PARTS OF THE SOUTHERN MO OZARKS EARLY THIS MORNING...BUT THIS SHOULD DISSIPATE BY MID MORNING. WEAK HIGH PRESSURE CENTERED OVER THE ARKLATEX REGION EARLY THIS MORNING WILL SHIFT TO THE EAST WITH A WEAK SOUTHERLY SFC FLOW DEVELOPING. AFTER THE STRATUS MIXES OUT...EXPECT VFR CONDITIONS THROUGH TONIGHT WITH ONLY HIGH CLOUDS AT TIMES. DSA && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 422 AM CST SAT DEC 29 2007 .DISCUSSION... LONGWAVE H500 TROF WILL REMAIN ENTRENCHED OVER MUCH OF THE CONUS UNTIL MONDAY...WHEN NWP MODELS THEN HAVE THIS FEATURE BEGIN TO SHIFT EWD...PLACING THE AREA INTO AN AREA OF BROAD NWLY MID LEVEL FLOW. THIS WOULD CONTINUE TO ALLUDE TO AN ACTIVE PATTERN...BUT MOISTURE WILL BE QUITE LIMITED...AND SHORTWAVE SYSTEMS WILL NOT BE AS DEEP OR STRONG AS THE PAST FEW. ONE SHORTWAVE TROF WILL MOVE THRU LATE SATURDAY NIGHT AND SUNDAY MORNING...MAINLY IMPACTING THE SRN/SERN FA...WITH A SECOND SHORTWAVE TROF TO THEN MOVE THRU LATE SUNDAY NIGHT AND MONDAY...ACCOMPANIED BY A STRONG CDFNT AT THE SURFACE. DEEP CYCLONIC FLOW WILL THEN SETUP OVER THE AREA NEW YEARS EVE AND DAY WITH A CLASSIC SNOW SHOWER SCENARIO...PRIMARILY FOR THE IL COUNTIES. SYSTEM NUMBER ONE LATE SAT NIGHT AND SUNDAY MORNING WILL BARELY CARRY ENOUGH MOISTURE TO EXCEED NORMAL LATE DECEMBER PWAT VALUES... AND WILL BE RATHER DRY AT H850. HAVE CARRIED A DRY POP FOR THIS EVENT. SHOULD PRIMARILY SEE INSTEAD A SWATH OF MID AND HI LEVEL CLOUD OVER THE SRN AND ERN FA. SYSTEM NUMBER TWO ON LATE SUN NIGHT AND MONDAY WILL HAVE A BIT MORE MOISTURE...DEEPER LIFT THRU THE COLUMN AND LESS SATURATION AT THE LOW LEVELS TO ACHIEVE. GFS DEPICTS A COLUMN MOISTENING UP QUICKER THAN THE NAM...AS WELL AS A SYSTEM THAT IS MORE IN PHASE WITH ITS NRN AND SRN COMPONENTS...WHEREAS THE NAM TAKES THESE TWO FEATURES SEPARATELY ACROSS THE FA. UNCERTAINTY AS TO WHICH ONE WILL VERIFY AND NOT ENOUGH OF A FEEL TO LEAN ONE WAY OR ANOTHER...BUT ALSO GIVEN STRONG CDFNT AT THE SFC MAKING ITS WAY THRU DURING MONDAY...FELT IT REASONABLE TO PLACE SMALL CHANCE POPS IN THE IL COUNTIES WHERE BETTER SATURATION SHOULD OCCUR. HAVE TRACE-TYPE PCPN IN THE MO COUNTIES. MAINLY FROZEN PCPN IN THE NRN FA AND LIQUID IN THE S...BUT AMOUNTS OVERALL WILL BE LIGHT WITH LITTLE OR NO SNOW ACCUM EXPECTED AT THIS TIME. SCT SNOW SHOWERS OR FLURRIES WILL THEN TAKE PLACE IN THE AFTERMATH ON MONDAY NIGHT AND TUESDAY WITH DEEP CYCLONIC FLOW...AN UPPER LEVEL DISTURBANCE ROTATING AROUND...AND SUFFICIENT MOISTURE TO SUPPORT PCPN. STRONG HI PRES OF 1045MB WILL THEN DOMINATE THE FA FOR MID WEEK AND TO RING IN 2008 ON A COLD NOTE. TES && .AVIATION... FOR THE 06Z TAFS...LOW LVL CLOUD CEILING ARND 2000 FT SHOULD SLOWLY CLR FM W TO E DURING THE LT NGT AND EARLY MRNG HRS AT THE TAF SITES. LOOKING AT LATEST SATELLITE LOOPS CLOUDS CLRG OUT OVER WRN MO ATTM. THIS CLRG SHOULD WORK EWD INTO COU JUST AFTER 06Z SAT AND IN UIN...STL AND SUS ARND 12Z SAT. LATEST RUC FCST AT 925 MB DEPICTS LWRG RH VALUES AT THIS LVL FM W TO E DURING THE OVERNIGHT HRS. WITH CLRG LT TGT IN COU MAY BE SOME FOG DVLPG WITH SATURATED GROUND FM RECENT PCPN AND WITH DIMINISHING SFC WND SPEEDS. SHOULD BE MAINLY HI LVL CLOUDS ON SAT. GUSTY WLY SFC WNDS SHOULD CONT TO DIMINISH DUIRNG THE OVERNIGHT HRS AS THE SFC LOW OVR NRN MICHIGAN CONTS MOVG FURTHER NE OF THE CWA AND AS SFC HI CNTRD OVR OK BLDS E-NEWD INTO MO. THE SFC WND WL BACK ARND TO A SWLY DIRECTION BY LT SAT MRNG AS THE SFC HI SHIFTS S-SE OF THE CWA. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 140 AM CST SAT DEC 29 2007 .DISCUSSION... SURFACE HIGH PRESSURE WAS SHIFTING ACROSS THE REGION THIS MORNING IN THE WAKE OF THIS MORNINGS UPPER LOW THAT FORCED SOME LIGHT RAIN AND SNOW IN MOST AREAS. SOME LINGERING STRATUS WAS LIMITING TEMPERATURES FROM FALLING INTO THE TEENS ALONG THE OZARK PLATEAU. THIS STRATUS WILL LIKELY BURN OFF QUICKLY UPON SUNRISE THIS MORNING. MEANWHILE...ANOTHER UPPER DISTURBANCE WILL APPROACH FROM THE WEST LATE TONIGHT. A MOISTURE STARVED ATMOSPHERE WILL KEEP CONDITIONS DRY THROUGH THE PASSAGE OF THIS SYSTEM. HOWEVER...I CAN NOT RULE OUT SOME PRECIP CHANCES FOR MONDAY AS A SURGE OF ARCTIC AIR RUSHES INTO THE REGION. THIS CHANGE IN AIRMASS WAS THE MAIN FORECAST CHALLENGE IN THIS MORNINGS ANALYSIS AS SINGLE DIGIT READINGS WILL BE POSSIBLE BY MID WEEK. SHORT TERM (TODAY - TUESDAY NIGHT)... RUC 275K POTENTIAL TEMPERATURE SURFACE EXPLAINS WHY STRATUS IS LINGERING ALONG AND SOUTH OF THE I-44 CORRIDOR. A TROUGH AXIS APPEARS TO BE STATIONARY NEAR THIS CORRIDOR...AND WEAK FLOW ACROSS THE AXIS IS PROVIDING A WEAK BAND OF LIFT IN THE FORM OF PRESSURE ADVECTION. AFTER SUNRISE...THE LOWER TROP WILL BEGIN TO MIX OUT WHICH WILL LIKELY DISSIPATE THIS LOW LEVEL ZONE OF COLDER AIR. UNDER MOSTLY SUNNY SKIES ALONG WITH A RETURN OF SOUTHERLY WINDS...TEMPERATURES WILL WARM INTO THE 40S THIS AFTERNOON. A SHORTWAVE TROUGH WILL APPROACH THE REGION LATE TONIGHT. DESPITE MODERATE FORCING IN ADVANCE OF THIS WAVE...PRESSURE CONDENSATION LEVELS ARE SO HIGH AND CAN NOT BE REALIZED DUE TO A VERY DRY AIRMASS. 00Z SOUNDINGS ACROSS THE CENTRAL AND SOUTHERN PLAINS MEASURED PWATS LESS THAN ONE QUARTER OF AN INCH. THEREFORE ONLY SOME MID AND UPPER LEVEL CLOUDS WILL RESULT FROM THE PASSAGE OF THIS DISTURBANCE. SOUTHERLY WINDS AT THE SURFACE AND CLEAR SKIES WILL BOOST TEMPERATURES UP A FEW MORE DEGREES FROM TODAYS EXPECTED READINGS. AS A MATTER OF FACT...I INCREASED TEMPERATURES IN MOST LOCATIONS A FEW DEGREES WARMER THAN MAV GUIDANCE. PROGGED SURFACE TO 850 THICKNESSES CORRELATES WITH TEMPERATURES APPROACHING THE LOWER 50S ON SUNDAY. AGAIN...NO PRECIPITATION IS EXPECTED THROUGH THE REST OF THE WEEKEND. ALL MEDIUM RANGE MODELS ARE IN GOOD AGREEMENT AND SHOW GOOD RUN TO RUN CONSISTENCY WITH A SURGE OF ARCTIC AIR DURING THE DAY ON MONDAY. TEMPERATURES AT THIS POINT WILL EXPERIENCE A COOLING TREND THROUGH WEDNESDAY. LOWER TEENS OR SINGLE DIGIT READINGS CAN NOT BE RULED OUT TUESDAY NIGHT INTO WEDNESDAY MORNING...AS THE COLDEST AREA OF THIS AIRMASS SPREADS DIRECTLY OVER THE EASTERN PLAINS AND OZARKS REGION. I INSERTED SOME SMALL POPS FOR MONDAYS DAY PERIOD. IT APPEARS AS THOUGH THERE WILL BE SOME UPPER SUPPORT CREATING LIFT AS THE ARCTIC SURGE OCCURS. MODELS SUGGEST A LOT OF DRY AIR ABOVE 500MB...HOWEVER...SUFFICIENT SHALLOW MOISTURE WILL EXIST FOR SLIGHT CHANCES OF LIGHT SNOW OR RAIN. LONG TERM (WEDNESDAY - FRIDAY)... FLOW OVER MOST OF THE NATIONS MID SECTION DURING THE LONG TERM WILL BE MOSTLY ZONAL AS A LONG WAVE RIDGE BEGINS TO DEAMPLIFY AS IT PROGRESSES OVERHEAD. THIS PATTERN SHOULD RESULT IN ABOVE NORMAL TEMPERATURES AND LITTLE TO NO RAIN CHANCES. DESPITE A GOOD POSSIBILITY OF SOUTHERLY FLOW...THE SURFACE PRESSURE PATTERN ACROSS THE GULF COAST STATES IS CONDUCIVE FOR OFF SHORE FLOW...ULTIMATELY SHUTTING DOWN ANY POSSIBLE MOISTURE RETURN. CRAMER && .AVIATION... FOR THE 06Z TAFS...STUBBORN MVFR STRATUS APPEARS TO BE MAKING ITS LAST STAND OVER SPRINGFIELD AND JOPLIN LATE THIS EVENING. HIGHER CLOUD DECK MOVING IN FROM THE SOUTHWEST IS MASKING BACK EDGE OF STRATUS ON INFRARED SATELLITE...SO ANY CLOUD INFO FROM PILOTS WOULD BE HELPFUL. BASED ON AREA SURFACE OBSERVATIONS AND UPPER FLOW MOVEMENT...WILL START THE KJLN TAF AT VFR AND IMPROVE CEILINGS TO VFR AT KSGF BY AROUND 07Z. WINDS SHOULD REMAIN LIGHT SOUTHWEST THROUGH THE NIGHT AS PRESSURE GRADIENT RELAXES IN WAKE OF SURFACE HIGH BUILDING ACROSS THE SOUTHERN PLAINS. ANOTHER UPPER TROUGH WILL APPROACH THE AREA THIS EVENING. DO NOT PLAN TO CARRY PRECIP AT THIS TIME BUT WILL LOWER A BROKEN DECK TO AROUND 10KFT AFTER 00Z. TERRY && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 1102 PM CST FRI DEC 28 2007 .DISCUSSION... SURFACE LOW OVER NORTHERN IL WILL CONTINUE TO LIFT OUT THIS EVENING. ON BACKSIDE OF SYSTEM...WILL STILL SEE SOME LIGHT FLURRY ACTIVITY FOR NORTHEASTERN SECTIONS OF CWA THROUGH MIDNIGHT. OTHERWISE...MAIN FORECAST ISSUE WILL BE CLOUDS AND TEMPS. SKIES WILL BE SLOW TO CLEAR TONIGHT WITH LOWS RANGING FROM AROUND 20 FAR NORTH...OVER SNOW FIELD...TO THE MID 20S FAR SOUTH AND EAST PORTIONS OF THE CWA. BY TOMORROW...WEAK RIDGING TO BUILD IN WITH PARTLY SUNNY SKIES AND WINDS BACKING TO THE SOUTH ONCE AGAIN. HIGHS WILL BE SIMILAR TO TODAY/S...IN THE MID 30S TO LOW 40S. SFC RIDGE TO MOVE OFF SATURDAY NIGHT AS NEXT UPPER LEVEL SHORTWAVE APPROACHES THE AREA. HOWEVER...LACK OF LOW LEVEL MOISTURE WILL MAKE PASSAGE OF THE SHORTWAVE A DRY ONE WITH LOWS IN THE MID TO UPPER 20S. MILD CONDITIONS WILL PREVAIL OVER THE AREA ON SUNDAY WITH TEMPERATURES IN THE UPPER 30S TO MID 40S. HOWEVER...NEXT SHORTWAVE TO APPROACH THE AREA SUNDAY NIGHT AND MONDAY. THIS SYSTEM IS A MUCH MORE ROBUST THAN PREVIOUS SYSTEM. STRONGEST ENERGY TO REMAIN JUST NORTH OF CWA...SO WILL KEEP SLIGHT CHANCE MENTION FOR NOW...WITH LIGHT SNOW/LIGHT RAIN FOR NORTHERN AND NORTHEASTERN PORTIONS OF CWA. BEYOND THAT NO MAJOR CHANGES TO THE EXTENDED AS STRONG SFC RIDGE BUILDS IN FOR THE REST OF THE WORK WEEK WITH A GRADUAL WARM UP TOWARDS NEXT WEEKEND. BYRD && .AVIATION... FOR THE 06Z TAFS...LOW LVL CLOUD CEILING ARND 2000 FT SHOULD SLOWLY CLR FM W TO E DURING THE LT NGT AND EARLY MRNG HRS AT THE TAF SITES. LOOKING AT LATEST SATELLITE LOOPS CLOUDS CLRG OUT OVER WRN MO ATTM. THIS CLRG SHOULD WORK EWD INTO COU JUST AFTER 06Z SAT AND IN UIN...STL AND SUS ARND 12Z SAT. LATEST RUC FCST AT 925 MB DEPICTS LWRG RH VALUES AT THIS LVL FM W TO E DURING THE OVERNIGHT HRS. WITH CLRG LT TGT IN COU MAY BE SOME FOG DVLPG WITH SATURATED GROUND FM RECENT PCPN AND WITH DIMINISHING SFC WND SPEEDS. SHOULD BE MAINLY HI LVL CLOUDS ON SAT. GUSTY WLY SFC WNDS SHOULD CONT TO DIMINISH DUIRNG THE OVERNIGHT HRS AS THE SFC LOW OVR NRN MICHIGAN CONTS MOVG FURTHER NE OF THE CWA AND AS SFC HI CNTRD OVR OK BLDS E-NEWD INTO MO. THE SFC WND WL BACK ARND TO A SWLY DIRECTION BY LT SAT MRNG AS THE SFC HI SHIFTS S-SE OF THE CWA. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 933 PM EST SUN DEC 30 2007 .SYNOPSIS... A STORM WILL MOVE NORTHEAST FROM THE MIDDLE ATLANTIC COAST OVERNIGHT TO CAPE COD MONDAY MORNING. THIS SYSTEM WILL BRING A WIDESPREAD SNOW TO THE REGION. AN ARCTIC COLD FRONT WILL CROSS THE AREA ON TUESDAY...ACCOMPANIED BY MORE SNOW...AND FOLLOWED BY BITTER COLD AIR. THE BITTER COLD AIR WILL LAST A COUPLE DAYS AS THERE WILL BE A MODERATING TREND BY THE END OF THE WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... NOT MUCH TO CHANGE WITH THIS UPDATE. ADJUSTED SNOWFALL AMOUNTS UP SLIGHTLY IN THE WARNING AREA OF THE WRN CATSKILLS TO OTSEGO COUNTY AND IN NORTHERN WAYNE CO PA. THINK UP TO 10 INCHES IS A DEFINITIVE POSSIBILITY IN THESE AREAS. LOCAL WRF MESOSCALE MODEL RUN AT 12Z...AND LATEST NAM 12 KM 00Z RUN SHOW AN INTENSIFYING BAND OF FGEN FORCING BETWEEN 750 AND 700 MB AS IT WORKS NE RAPIDLY FROM SC PA TO NE PA AND ERN NY. RADAR RETURNS AT PRESENT CORRELATE WELL TO THE 700-750 MB FGEN FORCING ON THE 00Z NAM12. THIS MODEL SHOWS THE MOST INTENSE FORCING REACHING THE CATSKILLS AND EXTREME NE PA BY 06Z. THUS HIGHER RADAR RETURNS IN SC PA WILL SPREAD RAPIDLY NE INTO THE WARNING AREA AND SLOW DOWN SOME IN THE NEXT 3 HOURS OR SO. IN ADDTN...THERE IS A LAYER OF NEG EPV THAT BEGINS TO EXPAND OVER THE CATSKILLS/EXT NE PA ABV THE FGEN LAYER TO FURTHER ENHANCE SNOWFALL RATES. THIS WHOLE PROCESS IS THE BEGINNING OF THE CLOSING OFF OF THE LOWER LEVEL CYCLONE AS IT REALLY GETS GOING FARTHER NE OF OUR AREA INTO NEW ENGLAND. BUT WE BELIEVE THE CATSKILLS TO OTSEGO COUNTY IS THE BEGINNING OF THE SWATH OF HEAVIER SNOW FROM THIS STORM. HEAVY SNOW SHUD REACH THESE AREAS BY 11 PM OR SO AND LAST UNTIL AROUND 3 AM. REST OF FORECAST AREA IS UNDER DEEP ISEN LIFT FM ARND 800 MB TO ALMOST 650 MB AS SEEN ON THE 285...290 AND 295 K SURFACES BETWEEN ROUGHLY 3 AND 9Z. THIS HAPPENS IN CONCERT WITH STRG UPR LVL LIFTG ASSCTD WITH 300 MB PV ADVECTION. ISENTROPES ARE BEING LIFTED AS THE AIR FLOWS UP THESE SURFACES. THIS IS IDEAL FOR WIDESPREAD LIGHT TO MODERATE SNOWS. ISEN LIFT IS STRGEST E OF A SYR TO WAVERLY NY TO IPT LINE THEREFORE SNOWS WILL BE A LITTLE HEAVIER IN THESE AREAS. THE NRN EDGE OF THE HIGHER RADAR RETURNS IN PA APPEARS TO BE TARGETING THESE AREAS AS WELL. ALSO THREW IN A LITTLE MORE ZR AND IP IN THE POCONOS/SRN CATSKILLS BASED ON THE OBS AND RADAR RETURNS WHICH LOOKS LIKE SOME SLEET IS MIXING IN. RUC13 AND GFS SOUNDINGS SUGGEST A SMALL WARM LAYER REACHES THIS AREA ARND 3Z OR SO...BUT SOON COOLS OFF. SO IT WILL BE A SMALL PERIOD AND MINIMAL. SNOW WILL WIND DOWN FIRST OVER NRN PA BY ARND 12Z...THEN LINGER A LITTLE LONGER UNTIL LATE MORNING IN NC AND EC NY...BUT IT WILL BE LIGHTER THAN THE OVERNIGHT HOURS. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY/... NEXT SYSTEM WILL PARADE THRU THE FA LATE MONDAY NIGHT THROUGH TUESDAY. THIS SYSTEM IS CURRENTLY LOCATED OVER PACIFIC NORTHWEST AND IS PROGGED TO DIVE INTO THE PLAINS OVRNGT. SFC LOW WILL DEVELOP IN RESPONSE AND CROSS THE OHIO VALLEY...APPCHG WNY BY 12Z TUESDAY. LATEST NAM GUIDANCE INDICATES H7 LOW WILL CLOSE OFF OVR FA WITH H5 RMNG FAIRLY OPEN AS IT MVS OVR CENTRAL FA. NAM GUIDANCE HAS BEEN TRENDING A LITTLE FURTHER SOUTH WITH UPPER FEATURES. NOT A WHOLE LOT OF DIFFERENCE BTWN NAM AND GFS THUS FAR AS BOTH CLOSE OF H7 LOW TO SOME EXTENT AND LV H5 FEATURE MORE AS IN OPEN TROF...ALBEIT GETTING A LITTLE STRONGER AND DEEPER. SFC LOW IS PROGGED TO TRACK ALONG THE NY/PA BORDER ON TUESDAY. AT THIS POINT...NAM DIFFERS IN THAT IT TRANSFERS ENERGY MORE TOWARD THE COAST AND RE-DEVELOPS LOW ALONG ERN SEABOARD WHILE GFS KEEPS A MORE CONSOLIDATED LOW INLAND. ALL THESE FEATURES WILL COME INTO PLAY REGARDING SNOWFALL AMNTS. FOR THE TIME BEING...HAVE GONE WITH A BLEND OF NAM/GFS QPF. BOTH MODELS INDICATE A POSSIBLE DRY SLOT TUE AFTERNOON AND THIS WILL DEPEND ON HOW FAR SOUTH H5 FEATURE EVENTUALLY TRACKS. BASED ON POSN OF SYSTEM THUS FAR...HAVE GONE WITH QPF FROM 0.25-0.50 INCHES FROM 00Z MON-00Z TUE. LESSOR AMNTS EXPECTED DOWN SOUTH IF DRY SLOT MATERIALIZES WITH HIGHER TOTALS OVR FINGER LAKES. PART OF THIS MAY BE ENHANCED BY LK EFFECT AS FLOW TRANSITIONS QUICKLY. LIMITING FACTOR FOR HIGH SNOWFALL TOTALS WILL BE LACK OF MOISTURE. EARLIER SYSTEM WILL TAKE A GOOD CHUNK OF THE MOISTURE WITH IT AND NOT EXPECTING A WHOLE LOT IN THE WAY OF RETURN AHEAD OF THIS NEXT SYSTEM. THAT BEING SAID THOUGH...COMPROMISE QPF BTWN NAM (MUCH HEAVIER OF THE TWO) AND GFS WUD STILL YIELD WARNING CRITERIA SNOWS FROM FINGER LAKES INTO ONEIDA CTY AND POSSIBLE ADVISORY DOWN TO THE SRN TIER...POSSIBLY ENHANCED DUE TO LAKE EFFECT. CUD SEE A BRIEF MIX WITH SLEET OVR NEPA WHERE LOWEST AMNTS ARE EXPECTED AS OF NOW. HAVE OPTED NOT TO ISSUE A WATCH FOR THIS SYSTEM AS OF YET DUE TO ONGOING WINTER HEADLINES. HOWEVER...WILL PLAY IT UP IN THE HWO FOR POSSIBLE SIGNIFICANT ACCUMS. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MAIN STORY DURING FIRST HALF OF THE EXTENDED PERIOD WILL BE MUCH COLDER AIRMASS AND LAKE EFFECT SNOW SHOWERS AS UPPER LEVEL LOW PRESSURE MOVES EAST ACROSS THE AREA AND COLD NORTHWEST FLOW ENSUES. AT THIS POINT, IT LOOKS LIKE THE FLOW WILL BE SUCH THAT THE LAKE EFFECT WILL BE PRIMARILY A LONG-LIVED, MULTI-BAND EVENT TARGETING AREAS SOUTH OF THE LAKES, AND THE FINGER LAKES REGION OF NEW YORK FROM TUESDAY NIGHT INTO THURSDAY. AFTER THAT, QUICK MODERATING TREND AS UPPER RIDGE AND HIGH PRESSURE AT SFC MOVE EAST TO COVER MOST OF THE EASTERN HALF OF THE COUNTRY. TEMPS LOOK TO REBOUND QUICKLY TO ABOVE NORMAL VALUES BY THE END OF THE PERIOD. && .AVIATION /02Z MONDAY THROUGH FRIDAY/... IFR IN -SN AND CIG SPREADING N QUICKLY INTO NRN PA AND SC NY WITH AVP DOWN TO IFR ALREADY...BGM AT MVFR. I EXPECT TAFS SITES ELM...BGM AND ITH TO BE IFR IN -SN BETWEEN 00Z AND 01Z. THE IFR SNOWS AND CIGS ARE EXPECTED TO REACH SYR AND RME BY 2-3Z. MESOSCALE MODELS INDICATE STRG LIFTG IN ASSCTN WITH FGEN FRCG AFFECTING NE PA TO EC NY BETWEEN 03Z AND 09Z SO I HAVE TIMED IN LIFR IN SN TO BGM/AVP AT THESE TIMES. HEAVIEST SNOW PROGRESSES N IN THIS TIME FRAME SO I HAVE ELM AND ITH GETTING DOWN TO 3/4SM IN THIS TIME FRAME AND EVENTUALLY RME AND SYR BETWEEN 06Z AND 11Z. AFTER THE HEAVIEST SNOW LEAVES THERE WILL BE A GRADUALLY IMPROVEMENT FROM IFR TO MVFR THEN TO VFR FM S TO N AS THE SNOWS TAPER BY 18Z. AFTER THE SYS PASSES BY TO OUR NE MON PM...I EXPECT SCT-BKN VFR SC WITH NO RESTRICTIONS. WINDS WILL BE FAIRLY LIGHT FROM THE E UNTIL ARND 08-10Z WHEN THEY SWITCH SW...THEN W BY ARND MID MORNING MON AND REACH CLSE TO 10 KNTS. MONDAY EVE THROUGH FRIDAY...VFR MOST PLACES MONDAY EVE. ANOTHER CHC FOR FLIGHT RESTRICTIONS LATE MONDAY NIGHT THROUGH TUESDAY AS ANOTHER SFC LOW MOVES THRU FROM THE OHIO VALLEY AND SPREADS SNOW BACK INTO THE AREA. CUD SEE MVFR/IFR RESTRICTIONS AGAIN WITH ANOTHER CHC FOR HVY SNOW...ESPECIALLY OVR NY TERMINALS. NORTHWEST FLOW ALONG WITH ARCTIC AIR WILL CONTINUE SNOW SHOWERS AND FLIGHT RESTRICTIONS THROUGH WEDNESDAY NIGHT BEFORE IMPROVING CONDITIONS ON THURSDAY AND FRIDAY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...SNOW ADVISORY UNTIL 11 AM EST MONDAY FOR PAZ038-039-043-044- 047-048-072. HEAVY SNOW WARNING UNTIL 11 AM EST MONDAY FOR PAZ040. NY...SNOW ADVISORY UNTIL 11 AM EST MONDAY FOR NYZ009-015>018- 022>025-036-037-044-045-055-056. HEAVY SNOW WARNING UNTIL 11 AM EST MONDAY FOR NYZ046-057-062. && $$ SYNOPSIS...DJN NEAR TERM...DJN SHORT TERM...MSE/TAC LONG TERM...PVB AVIATION...DJN ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 629 PM EST SUN DEC 30 2007 .SYNOPSIS... A STORM WILL MOVE NORTHEAST ALONG THE EAST COAST TODAY INTO MONDAY...BRINGING SNOW TO THE REGION. AN ARCTIC COLD FRONT WILL CROSS THE AREA ON TUESDAY... ACCOMPANIED BY MORE SNOW... AND FOLLOWED BY MUCH COLDER WEATHER. && .NEAR TERM /UNTIL 11 PM THIS EVENING/... INITIAL SHOT OF LIGHT SNOW IS WORKING NORTHEAST ACROSS CENTRAL PA LATE THIS AFTERNOON. SOME VERY LIGHT SNOW WILL SPREAD ACROSS NORTHEAST PA THROUGH 5 PM... BUT THIS PROGRESSION WILL LIKELY SLOW AS THE PRECIPITATION BEGINS TO OUTRUN ITS FORCING. MAIN SHOT OF LIFT IS STILL EXPECTED TO OVERSPREAD THE AREA THIS EVENING... AND THIS IS THE TIME WHEN SNOW SHOULD EXPAND ACROSS THE ENTIRE FORECAST AREA. THERE IS STILL A CONCERN FOR SOME MIXED PRECIPITATION DURING THE ONSET OF THIS EVENT ACROSS NORTHEAST PA. THE GFS FORECAST SOUNDING AT AVP IS WARM ENOUGH TO SUPPORT MIXED PRECIPITATION UNTIL AROUND 06Z. THE NAM... LOCAL ARW AND RUC ARE SOMEWHAT COLDER AND WOULD CONFINE MIXED PRECIPITATION MAINLY TO AREAS SOUTH OF I-80. THE BEST FORCING FOR LIFT STILL APPEARS TO BE ACROSS THE SOUTHEASTERN HALF OF THE FORECAST AREA LATE THIS EVENING THROUGH ABOUT 09Z WHEN SIGNIFICANT FRONTOGENESIS IS FORECAST TO DEVELOP CO-LOCATED WTIH REDUCED STABILITY. THIS SHOULD FORCE A BAND OF MODERATE TO HEAVY SNOW FROM THE NORTHERN POCONOS NORTHEAST INTO THE CATSKILLS. HAVE GONE WITH A HEAVY SNOW WARNING FOR UP TO 8 INCHES IN THAT AREA. FARTHER TO THE WEST... BANDING SIGNALS ARE NOT AS IMPRESSIVE... BUT BROAD-SCALE LIFT FOR SEVERAL HOURS SHOULD STILL BE ENOUGH TO PRODUCE A WIDESPREAD 3 TO 6 INCH SNOW EVENT. && .SHORT TERM /11 PM THIS EVENING THROUGH TUESDAY/... NEXT SYSTEM WILL PARADE THRU THE FA LATE MONDAY NIGHT THROUGH TUESDAY. THIS SYSTEM IS CURRENTLY LOCATED OVER PACIFIC NORTHWEST AND IS PROGGED TO DIVE INTO THE PLAINS OVRNGT. SFC LOW WILL DEVELOP IN RESPONSE AND CROSS THE OHIO VALLEY...APPCHG WNY BY 12Z TUESDAY. LATEST NAM GUIDANCE INDICATES H7 LOW WILL CLOSE OFF OVR FA WITH H5 RMNG FAIRLY OPEN AS IT MVS OVR CENTRAL FA. NAM GUIDANCE HAS BEEN TRENDING A LITTLE FURTHER SOUTH WITH UPPER FEATURES. NOT A WHOLE LOT OF DIFFERENCE BTWN NAM AND GFS THUS FAR AS BOTH CLOSE OF H7 LOW TO SOME EXTENT AND LV H5 FEATURE MORE AS IN OPEN TROF...ALBEIT GETTING A LITTLE STRONGER AND DEEPER. SFC LOW IS PROGGED TO TRACK ALONG THE NY/PA BORDER ON TUESDAY. AT THIS POINT...NAM DIFFERS IN THAT IT TRANSFERS ENERGY MORE TOWARD THE COAST AND RE-DEVELOPS LOW ALONG ERN SEABOARD WHILE GFS KEEPS A MORE CONSOLIDATED LOW INLAND. ALL THESE FEATURES WILL COME INTO PLAY REGARDING SNOWFALL AMNTS. FOR THE TIME BEING...HAVE GONE WITH A BLEND OF NAM/GFS QPF. BOTH MODELS INDICATE A POSSIBLE DRY SLOT TUE AFTERNOON AND THIS WILL DEPEND ON HOW FAR SOUTH H5 FEATURE EVENTUALLY TRACKS. BASED ON POSN OF SYSTEM THUS FAR...HAVE GONE WITH QPF FROM 0.25-0.50 INCHES FROM 00Z MON-00Z TUE. LESSOR AMNTS EXPECTED DOWN SOUTH IF DRY SLOT MATERIALIZES WITH HIGHER TOTALS OVR FINGER LAKES. PART OF THIS MAY BE ENHANCED BY LK EFFECT AS FLOW TRANSITIONS QUICKLY. LIMITING FACTOR FOR HIGH SNOWFALL TOTALS WILL BE LACK OF MOISTURE. EARLIER SYSTEM WILL TAKE A GOOD CHUNK OF THE MOISTURE WITH IT AND NOT EXPECTING A WHOLE LOT IN THE WAY OF RETURN AHEAD OF THIS NEXT SYSTEM. THAT BEING SAID THOUGH...COMPROMISE QPF BTWN NAM (MUCH HEAVIER OF THE TWO) AND GFS WUD STILL YIELD WARNING CRITERIA SNOWS FROM FINGER LAKES INTO ONEIDA CTY AND POSSIBLE ADVISORY DOWN TO THE SRN TIER...POSSIBLY ENHANCED DUE TO LAKE EFFECT. CUD SEE A BRIEF MIX WITH SLEET OVR NEPA WHERE LOWEST AMNTS ARE EXPECTED AS OF NOW. HAVE OPTED NOT TO ISSUE A WATCH FOR THIS SYSTEM AS OF YET DUE TO ONGOING WINTER HEADLINES. HOWEVER...WILL PLAY IT UP IN THE HWO FOR POSSIBLE SIGNIFICANT ACCUMS. && .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... MAIN STORY DURING FIRST HALF OF THE EXTENDED PERIOD WILL BE MUCH COLDER AIRMASS AND LAKE EFFECT SNOW SHOWERS AS UPPER LEVEL LOW PRESSURE MOVES EAST ACROSS THE AREA AND COLD NORTHWEST FLOW ENSUES. AT THIS POINT, IT LOOKS LIKE THE FLOW WILL BE SUCH THAT THE LAKE EFFECT WILL BE PRIMARILY A LONG-LIVED, MULTI-BAND EVENT TARGETING AREAS SOUTH OF THE LAKES, AND THE FINGER LAKES REGION OF NEW YORK FROM TUESDAY NIGHT INTO THURSDAY. AFTER THAT, QUICK MODERATING TREND AS UPPER RIDGE AND HIGH PRESSURE AT SFC MOVE EAST TO COVER MOST OF THE EASTERN HALF OF THE COUNTRY. TEMPS LOOK TO REBOUND QUICKLY TO ABOVE NORMAL VALUES BY THE END OF THE PERIOD. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... IFR IN -SN AND CIG SPREADING N QUICKLY INTO NRN PA AND SC NY WITH AVP DOWN TO IFR ALREADY...BGM AT MVFR. I EXPECT TAFS SITES ELM...BGM AND ITH TO BE IFR IN -SN BETWEEN 00Z AND 01Z. THE IFR SNOWS AND CIGS ARE EXPECTED TO REACH SYR AND RME BY 2-3Z. MESOSCALE MODELS INDICATE STRG LIFTG IN ASSCTN WITH FGEN FRCG AFFECTING NE PA TO EC NY BETWEEN 03Z AND 09Z SO I HAVE TIMED IN LIFR IN SN TO BGM/AVP AT THESE TIMES. HEAVIEST SNOW PROGRESSES N IN THIS TIME FRAME SO I HAVE ELM AND ITH GETTING DOWN TO 3/4SM IN THIS TIME FRAME AND EVENTUALLY RME AND SYR BETWEEN 06Z AND 11Z. AFTER THE HEAVIEST SNOW LEAVES THERE WILL BE A GRADUALLY IMPROVEMENT FROM IFR TO MVFR THEN TO VFR FM S TO N AS THE SNOWS TAPER BY 18Z. AFTER THE SYS PASSES BY TO OUR NE MON PM...I EXPECT SCT-BKN VFR SC WITH NO RESTRICTIONS. WINDS WILL BE FAIRLY LIGHT FROM THE E UNTIL ARND 08-10Z WHEN THEY SWITCH SW...THEN W BY ARND MID MORNING MON AND REACH CLSE TO 10 KNTS. MONDAY EVE THROUGH FRIDAY...VFR MOST PLACES MONDAY EVE. ANOTHER CHC FOR FLIGHT RESTRICTIONS LATE MONDAY NIGHT THROUGH TUESDAY AS ANOTHER SFC LOW MOVES THRU FROM THE OHIO VALLEY AND SPREADS SNOW BACK INTO THE AREA. CUD SEE MVFR/IFR RESTRICTIONS AGAIN WITH ANOTHER CHC FOR HVY SNOW...ESPECIALLY OVR NY TERMINALS. NORTHWEST FLOW ALONG WITH ARCTIC AIR WILL CONTINUE SNOW SHOWERS AND FLIGHT RESTRICTIONS THROUGH WEDNESDAY NIGHT BEFORE IMPROVING CONDITIONS ON THURSDAY AND FRIDAY. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...SNOW ADVISORY UNTIL 11 AM EST MONDAY FOR PAZ038-039-043-044- 047-048-072. HEAVY SNOW WARNING UNTIL 11 AM EST MONDAY FOR PAZ040. NY...SNOW ADVISORY UNTIL 11 AM EST MONDAY FOR NYZ009-015>018- 022>025-036-037-044-045-055-056. HEAVY SNOW WARNING UNTIL 11 AM EST MONDAY FOR NYZ046-057-062. && $$ SYNOPSIS...MSE/TAC NEAR TERM...MSE SHORT TERM...MSE/TAC LONG TERM...PVB AVIATION...DJN ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1253 AM EST SAT DEC 29 2007 .SYNOPSIS... LOW PRESSURE CENTERED OVER MICHIGAN LATE THIS EVENING...WILL TRACK NORTHEAST INTO QUEBEC SATURDAY MORNING. MAINLY RAIN WILL BE ACROSS THE AREA TONIGHT...BEFORE ENDING AROUND DAYBREAK ON SATURDAY. LINGERING LIGHT RAIN OR SNOW SHOWERS WILL BE POSSIBLE DURING THE DAY. HIGH PRESSURE WITH FAIR AND MILD WEATHER WILL BE ACROSS THE REGION SATURDAY NIGHT AND SUNDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SATL IMAGERY SHOWS A VIGOUROUS UPR LVL WAVE TRACKING INTO LWR MI. AHEAD OF THIS FEATURE IS STRG LL WAA/ISENT LIFT AND UPR LVL DRVG. THIS SYSTEM HAS A FAIRLY WELL DEVELOPED MOISTURE FEED AND AS A RESULT LIGHT TO MODERATE WIDESPREAD PRECIPITATION WILL QUICKLY ENGULF C NY/NE PA THIS EVENING. RUC13...NAM 12 SOUNDINGS INDICATE THAT ENUF OF A WARM LAYER WILL ADVECT IN ALOFT LEADING TO A RAIN SOUNDING IN MOST AREAS. BNDRY LYR TEMPS WILL BEGIN BLO FREEZING IN NRN ONEIDA CO AND THE HIGHEST ELEVATIONS IN DELAWARE...OTSEGO AND SULLIVAN...STUEBEN CO/S IN NY AND BRADFORD/WYOMING CO/S IN PA. MESONET OBS SUGGEST TEMPS AT OR BLO FRZG ABV 2200 FEET WHICH IS A VERY LIMITED AREA IN THESE COUNTIES. IN ADDTN...THE WARM LAYER REACHES FM +5 TO +7C BETWEEN 800 AND 900 MB INDICATING A RISE IN TEMPS ABV FRZG ALL ELEVATIONS SOON AFTER PRECIP STARTS. WET BULB TEMPS WERE NOT THAT COLD EITHER. I PUT SOME FZRA IN THE HIGHEST GRID POINTS IN MUCH OF NE PA/ C NY FOR THIS EVENING WHICH IS VERY LIMITED. FARTHER N...WARM LAYER REACHES +2 TO +4C AND I DON/T EXPECT PRECIP TO BE THAT HEAVY...SO I EXPECT A LONGER PERIOD OF LIGHT FZRA OVER THE HIGHER TERRAIN OF NRN ONEIDA CO MAINLY. LOCAL WRF SUGGESTS PRECIP BEGINS AS SNOW UP THERE...BUT LATEST NAM AND RUC ARE MUCH WARMER. OPTED FOR JUST FZRA. ISSUED AN ADVY FOR NRN ONEIDA CO TO COVER THIS. REST OF FORECAST AREA JUST RAIN. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... DRY SLOT MVS IN QUICK WITH AN END TO THE PCPN BY 12Z SATURDAY. CUD SEE SOME LINGERING RA/SN SHOWERS ON SATURDAY. NOT TOO IMPRESSED WITH LAKE EFFECT POTENTIAL AS DENDRITE ZONE NOT FAVORABLE FOR MUCH IN THE WAY OF SNOW ACCUMS. HOWEVER...HAVE KEPT 30-40 POPS OVR NRN ZONES THRU SAT NIGHT. EXPECT HIGH PRESSURE TO RMN IN CONTROL THRU SUNDAY AFTERNOON BEFORE NEXT STORM SYSTEM BEGINS TO APPROACH FROM THE SOUTHEAST. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... ONE MAIN SYNOPTIC STORM DURING THE EXTENDED PERIOD, AND THE GFS HAS COME A BIT FURTHER WEST WITH THIS SYSTEM SUNDAY NIGHT INTO MONDAY. THIS WOULD BRING BETTER CHC FOR SOME ACCUMULATING SNOW OVER SOUTHEAST HALF OF THE FORECAST AREA, ESPECIALLY POCONOS INTO SRN CATSKILLS. BUMPED POPS AND QPF UP, BUT DID NOT GO TOO CRAZY WITH IT AS THESE SYSTEMS HAVE BEEN DIFFICULT THIS WINTER AND CONFIDENCE IS NOT TOO HIGH AT THIS POINT. THUS FAR, GFS IS RATHER WEAK WITH THE LOW AS IT MOVES OFF COAST NEAR THE OUTER BANKS AND WELL SOUTH OF NEW ENGLAND. AFTER THAT, A WEAK CLIPPER SYSTEM IS PROGGED TO MOVE THRU TUESDAY, WITH ANOTHER CHC FOR SOME LIGHT SNOW. TEMPS GET MUCH COLDER FOR WEDNESDAY BEFORE MODERATION AGAIN AS SFC HIGH TRIES TO BUILD EAST AND HEIGHTS RISE. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... SHOWERS WILL CONTINUE OVER THE TERMINALS THROUGH 09Z- 10Z, WITH WIDESPREAD MVFR CONDITIONS PRIMARILY DUE TO CIGS. IFR, CONDITIONS DUE TO CIGS ARE POSSIBLE AT KBGM/KITH THROUGH 09Z. CIGS WILL LIFT TO VFR BTW 14Z-15Z, AND REMAIN VFR FOR REMAINDER OF TAF VALID TIME. S/SE WINDS AT 10 TO 15 KNOTS WITH GUSTS TO 25 KNOTS WILL SHIFT TO SOUTHWEST BY MID MORNING. TOWARD EVENING WINDS WILL SUBSIDE TO AROUND 10 KNOTS BUT CONTINUE FROM THE SOUTHWEST. SATURDAY THROUGH WEDNESDAY... VFR CONDITIONS WILL CONTINUE THROUGH SUNDAY AS FLOW GOES SW AHEAD OF THE NEXT SYSTEM. FOR SUNDAY EVENING AVP MAY FALL TO MVFR CIG AND VSBY IN LIGHT SNOW WITH A COASTAL STORM. BGM MAY ALSO GET INTO THE MVFR CIGS. REST OF SITES LESS LIKELY. NEXT MAJOR WEATHER MAKER AND CHANCE OF MVFR/IFR RESTRICTIONS MOVING IN LATE ON MONDAY AND CONTINUING INTO WED. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...FREEZING RAIN ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NYZ009. && $$ SYNOPSIS...DJN/TAC NEAR TERM...DJN SHORT TERM...PVB LONG TERM...JML AVIATION...RRM ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 313 AM CST SUN DEC 30 2007 .SHORT TERM... PROBLEM TODAY AND NEXT FEW DAYS IS MORE AVIATION AND CLOUD HEIGHTS...HOW FAR EAST CAN THE CLEARING OF LOW CLOUDS GET TODAY. ON THE PUBLIC FCST SIDE...LITTLE CHANGE IN PREV FCST WAS MADE. 08Z SFC MAP SHOWS WEAK SFC LOW NEAR DICKINSON ND WITH TROUGH SOUTHEAST INTO SD AND NORTHWEST TO ANOTHER WEAK LOW IN SOUTHERN ALBERTA. WATER VAPOR AND 500 MB RUC HEIGHT FIELDS INDICATE BROAD TROUGH OVER NRN PLAINS AND SRN CANADA. ONE VORT MAX IN THE 500 MB FLOW WAS NOTED IN FAR SRN MANITOBA AND SOME LIGHT SNOW HAS BEEN OCCURRING WITH THIS FEATURE FROM BRANDON TO WINNIPEG WITH ECHOES FROM WOODLAND MB AND KMVX RADARS SHOWING SOME LIGHT SNOW LIKELY AS WELL OVER PARTS OF FAR NE ND/NW MN. MODELS CONTINUE TO HIT AT THIS AREA WITH BEST SATURATION AT 850 MB TODAY AND BEST CHC OF SEEING SOME LIGHT SNOW. OTHERWISE...LOW CLOUDS HANGING FROM THE RED RIVER VALLEY EASTWARD. AS WINDS TURN LIGHT TODAY AND MIXING DECREASES NOT SURE ABOUT DEGREE OF LOW CLOUD REMOVAL AS NOTICING A SURGE OF LOW CLOUDS BACK SOUTHEAST FROM SE SASK ON BACKSIDE OF VORT .ALSO SOME MID AND HIGH LEVEL MOISTURE ABOVE THE CLOUDS TODAY...SO WILL KEEP WITH HIGH CLOUD PERCENTAGES IN THE GRIDDS....THOUGH CERTAINLY SOME AREAS COULD SEE THE SUN FOR A TIME TODAY (NAMELY WEST AND SOUTH OF FARGO). TEMPS TODAY LOOK WARMEST THIS MORNING AND MORE OF A STEADY STATE THE REST OF THE DAY AS 850 MB TEMPS COOL SLOWLY AFTER 12Z. AS PACIFIC STORM MOVES CLOSER TO THE WA/OR COAST...500 MB RIDGE WILL DEVELOP NORTHWARD INTO B.C. HELPING TO DISLODGE CURRENT 500 MB LOW IN CNTRL CANADA SOUTHWARD INTO NRN MN MONDAY. A DECENT COLD SHOT EXPECTED WITH THIS FEATURE AS 850 MB TEMPS FALL TO -18 TO -20C MON NIGHT-TUESDAY. ALSO LOTS OF CLOUDS WITH THIS FEATURE AS WELL ALONG WITIH SOME AREAS OF LIGHT SNOW/FLURRIES. THIS COVERED WELL FROM PREV FCST SO LITTLE CHANGE WAS NEEDED. UPPER LOW PULLS EAST ON TUESDAY WITH BEST CHC OF CLEARING TUES AFTN INTO TUES NIGHT AS HIGH PRESSURE MOVES OVERHEAD. COLDEST NIGHT LOOKS TO BE TUES NIGHT...THOUGH RETURN FLOW SETTING UP IN ERN ND WILL PREVENT COMPLETE DROP OFF IN TEMPS. .LONG TERM... NO CHANGES WERE MADE. AFTER A QUICK COLD SHOT MILDER WEATHER IN STORE THU-FRI AS LOW PRESSURE MOVES THRU SRN CANADA AND FCST AREA ON WARM SIDE OF SYSTEM. JUST HOW WARM OF COURSE ALWAYS THE ISSUE WITH PACIFIC AIRMASS OVER AREA AND PSBLY THE USUAL CLOUDS THAT MAY BE PRESENT IN MOIST WESTERLY FLOW. CURRENT FCST SEEMS OK. && .AVIATION... NOT MUCH CONFIDENCE IN HOW LOW CLOUDS WILL HANDLE TODAY IN THE VALLEY (FAR-GFK TAF SITES). ANOTHER SURGE OF LOW CLOUDS HEADED TOWARD MINOT AND DVL THIS MORNING WHERE JUST MID CLOUDS ARE CURRENTLY LOCATED. THUS NOT TREMENDOUSLY OPTIMISTIC OF MUCH LOW CLOUD CLEARING. BEMIDJI WOULD STAND THE LEAST CHC. AS IN PAST MORNINGS WOULD EXPECT SOME MVFR VSBYS (3-5 SM IN BR) AND CIGS LOWERING A BIT TO THE IFR RANGE IN TAF SITES...THEN RECOVERING A BIT BACK INTO MVFR RANGE DURING THE BALANCE OF THE DAY. SOUTHERLY WINDS WILL BECOME LIGHT AND VARIABLE BY THIS AFTN WITH SFC TROUGH MOVING THRU. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 501 PM EST SUN DEC 30 2007 .SYNOPSIS... HIGH PRESSURE MOVING THROUGH THE SOUTHERN UNITED STATES WILL PROVIDE DRY WEATHER TONIGHT THROUGH EARLY MONDAY. LOW PRESSURE TRAVELING THROUGH THE GREAT LAKES WILL DRAG A STRONG COLD FRONT ACROSS THE REGION MONDAY NIGHT...USHERING IN MUCH COLDER AIR AND SNOW SHOWERS FOR THE NEW YEAR. THE CHANCE FOR SNOW SHOWERS WILL CONTINUE THROUGH WEDNESDAY IN THE COLD NORTHWEST FLOW BEHIND THE FRONT. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... SKY COVER WILL DIMINISH AS A SOUTHERLY FLOW INITIATES BETWEEN HIGH PRESSURE TO THE SOUTH AND DEVELOPING LOW PRESSURE TO THE NORTHWEST. RADAR ECHOES ASSOCIATED WITH A WEAK UPPER AIR DISTURBANCE ARE NOT REACHING THE GROUND SO KEPT POPS IN THE 5 TO 14 PERCENT RANGE WHICH IS BELOW GUIDANCE. MADE NO CHANGES LOWS IN THE UPPER 20S TO AROUND 30 SINCE GUIDANCE HAS BEEN CONSISTENT IN THAT RESPECT. && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... WENT WITH GFS SOLUTION WHICH HAS BEEN MORE CONSISTENT WITH LOW TRACK AND QPF. GFS SCENARIO HAS THE LOW MOVING FROM NORTHERN ILLINOIS AT 18Z MONDAY TO LAKE ERIE AT 06Z TUESDAY THEN INTO NEW YORK STATE BY 12Z. THE LOW AND ASSOCIATED COLD FRONT ARE FORECAST TO CARRY A LIGHT AMOUNT OF PRECIPITATION INTO THE ILN AREA. THIS IS IN CONTRAST TO THE NAM WHICH HAS A STRONGER LOW MOVING THROUGH CENTRAL OHIO WHICH IS FORECAST TO PRODUCE HEAVIER PRECIPITATION. RAISED POPS SLIGHTLY FOR MONDAY NIGHT WITH SOME LOCATIONS APPROACHING 80 PERCENT. KEPT SNOW ACCUMULATIONS AN INCH OR LESS. BEHIND THE LOW...THE FLOW OFF LAKE MICHIGAN WILL BE FAVORABLE FOR SNOW SHOWERS TUESDAY AND TUESDAY NIGHT. KEPT HIGH CHANCE POPS...AND SOME LOCATIONS MAY RECEIVE ANOTHER INCH OR TWO ACCUMULATION THROUGH THAT PERIOD. ALSO...WINDS WILL BE BRISK WITH GUSTS TO 35 MPH POSSIBLE. TEMPERATURES WILL FALL FROM ABOVE NORMAL ON MONDAY TO BELOW NORMAL TUESDAY AND TUESDAY NIGHT. REDUCED FORECAST TEMPERATURES TUESDAY AND TUESDAY NIGHT...WHEN LOWS MAY FALL INTO THE LOWER TEENS. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... DURING THE FIRST PART OF THE EXTENDED...THE OHIO VALLEY REGION WILL BE ON THE BACK SIDE OF AN UPPER LEVEL TROF AND BEHIND A COLD FRONT. THE REGION WILL SEE MUCH COLDER AIR ON WEDNESDAY INTO THURSDAY WITH HIGHS WEDNESDAY IN THE 20S AND LOWS WEDNESDAY NIGHT RANGING FROM AROUND 10 DEGREES TO NEAR 15 DEGREES. IN ADDITION...SHORTWAVES WILL FINISH ROTATING AROUND THE UPPER TROF AND SCT LIGHT SNOW SHOWERS WILL COME TO AN END WEDNESDAY AFTERNOON/EVENING. THERE IS THE POTENTIAL FOR SOME LIGHT SNOW ACCUMULATIONS OF A FEW INCHES WHERE SNOW BANDS ARE HEAVIER AND PERSIST. BY WEDNESDAY NIGHT HIGH PRESSURE WILL BEGIN BUILDING INTO THE OHIO VALLEY REGION. THE COLD TEMPERATURES WILL BE SHORT LIVED. AS AN UPPER RIDGE BUILDS INTO THE REGION...A SURFACE HIGH WILL MOVE SE OF THE OHIO VALLEY REGION. SOUTHERLY FLOW WILL DEVELOP BY FRI ON THE BACK SIDE OF THE SURFACE HIGH...BRINGING A GRADUAL WARMING TREND THROUGH THE WEEKEND. AN UPPER LEVEL SYSTEM WILL EFFECT THE REGION SATURDAY AND A WEAK COLD FRONT WILL MOVE THROUGH THE OHIO VALLEY REGION SUNDAY BRINGING THE CHANCE OF PRECIPITATION BACK TO THE REGION. FOR THE MOST PART...THE TEMPERATURES WILL BE WARM ENOUGH FOR RAIN ALTHOUGH THERE MAY BE SOME SNOW EARLY ON. HIGH TEMPERATURES BY SUNDAY WILL BE MAINLY IN THE 50S WITH SOME LOCATIONS SEEING UPPER 40S. && .AVIATION /21Z SUNDAY THROUGH FRIDAY/... PLENTY OF CLOUDS STREAMING THRU REGION AHEAD OF MID LVL S/WV. S/WV WILL LIFT INTO GRT LKS THIS EVNG...POSSIBLY PRODUCING A FEW FLURRIES AT KDAY. CURRENT RUC ANALYSIS INDCG MODEL SEEMS TO HAVE THE BEST HANDLE ON BNDRY LYR MOISTURE FOR THE AFTN HOURS. DRIER LO LVL AIR COURTESY OF E/SE FLO HAS PUSHED MUCH OF THE MVFR SC WEST OF THE TERMINALS INTO INDIANA. THIS SHOULD HOLD FOR MUCH OF THE REST OF THE AFTN BEFORE DEEPER BNDRY LYR MOISTURE SPREADS BACK IN AS S/WV PASSES TO THE NW. KCVG/KLUK SHOULD BE MAINLY SPARED OF THE BKN MVFR DECK...BUT EXPECT IT WILL AFFECT NORTHERN TERMINALS DURING THE EVNG. WEAK SFC HI PRES RIDGE WILL BUILD INTO THE OH VLY LATE TONIGHT...AND SHOULD HELP SCATTER OUT THE LOWER CLOUDS DURING THE SECOND HALF OF THE OVERNIGHT. EXCEPTION WILL BE IN CNTRL OH WHERE MODEL SOUNDINGS INDCG MVFR CIGS MAY HOLD ALL NIGHT. MID LVL CLOUDS WILL QUICKLY BEGIN TO SPREAD BACK INTO THE FCST AREA FROM THE WEST DURING THE LATE MRNG MONDAY IN ADVANCE OF THE NEXT SYSTEM TO AFFECT REGION MON EVNG. VRB WINDS THIS AFTN WILL VEER TO S/SW TONIGHT BEHIND THE S/WV. OUTLOOK...MVFR/IFR CIGS/VSBYS POSSIBLE MONDAY NIGHT INTO WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...CONIGLIO NEAR TERM...CONIGLIO SHORT TERM...CONIGLIO LONG TERM...PARKER AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1248 PM EST SUN DEC 30 2007 .SYNOPSIS... A WEAK UPPER LEVEL DISTURBANCE CARRYING LIMITED MOISTURE WILL SWING ACROSS THE NORTHERN PORTIONS OF THE REGION THIS AFTERNOON. LOW PRESSURE TRAVELING THROUGH THE GREAT LAKES WILL DRAG A STRONG COLD FRONT ACROSS THE REGION MONDAY NIGHT...USHERING IN MUCH COLDER AIR AND SNOW SHOWERS FOR THE NEW YEAR. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PLENTY OF CLOUDS STREAMING ACRS FCST AREA THIS MRNG AS OH VLY SITS ON BACK SIDE OF SFC LO PRES ACRS THE SRN APPALACHIANS. WEAK MID LVL S/WV BRINGING SOME FLURRIES AND ISOLD -SHSN TO PORTIONS OF INDIANA. TEMPS REMAINED IN THE U20S/L30S. RETURNS SHOWING UP ON RADAR MOSAIC ACRS INDIANA AND EXTNDG INTO NW OHIO. WITH EXCEPTION OF FEW REPORTS OF FLURRIES/-SHSN OVER SWRN INDIANA...APPEARS MAJORITY OF THESE RETURNS ARE NOT MAKING IT TO THE GROUND. AS S/WV SWINGS THRU NW OHIO THIS AFTN...MID LVL DEFORMATION AXIS STRENGTHENS WITH ISENT LIFT AT 285K LVL BECOMG NEARLY SATURATED OVER WEST CNTRL OH. WILL CONTINUE 30 POPS ROUGHLY NORTHWEST OF A RICHMOND-SPRINGFIELD-DELAWARE LINE FOR THE AFTN AND INTO THE EVNG. 12Z NAM CONTINUES TO BE TOO GENEROUS WITH QPF...AND HAVE LEANED MORE TOWARDS 06Z/12Z OP GFS WHICH SHOW ONLY A FEW HUNDREDTHS OF QPF THRU THE EVNG HOURS. MANY LOCATIONS WILL PROBABLY SEE TRACE AMOUNTS AT BEST. MODEL SOUNDINGS SUPPORTING PCPN TO FALL AS -SHSN. INCREASED CLOUD COVER FOR AFTN HOURS AS WELL. MAY SEE A FEW BREAKS IN MID LVL DECK ACRS SW FCST AREA...BUT LITTLE TO NO SUN EXPECTED FOR AFTN. HAVE ALSO DROPPED TEMPS A GOOD 3-5 DEG ACRS THE BOARD FROM PREV FCST HIGHS. CLOUDS ARE ONCE AGAIN SLOWING TEMP RISES TODAY AND SHOULD CONTINUE TO DO SO FOR THE DURATION OF THE AFTN WITH MOST LOCATIONS STAYING IN THE 30S. AM A LITTLE CONCERNED THAT EVEN WITH DROPPING TEMPS SVRL DEG MAY STILL BE TOO WARM. WILL MONITOR TEMP PROGRESSION INTO THE AFTN TO DETERMINE IF AN ADDL UPDATE WOULD BE NEEDED. ZONE AND GRID UPDATES OUT. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... S/W IS EJECTING OUT AT BEGINNING OF THE PERIOD. WEAK SFC RIDGE THEN BUILDS IN FOR LATE TONIGHT. MODELS ARE IS AGREEMENT WITH THE CDFNT THAT DROPS OUT OF THE PLAIN MONDAY INTO MONDAY NIGHT. MODELS HAVE SLOWED THE ONSET OF THE PCPN MONDAY AFTN...SO LOWERED POPS. CDFNT THEN PUSHES ACRS THE REGION MON NGT. PREFER THE WETTER GFS. INCREASED POPS MON NGT. PCPN WILL START AS EITHER RAIN OR RAIN SNOW MIX...THEN CHANGE TO ALL SNOW AS THICKNESSES DROP IN. TEMPS WILL RISE A DEGREE OR TWO OR WILL DROP DURING THE DAY TUESDAY AS ARCTIC AIR WORKS IN ACROSS THE LAKES. WITH -12C AIR FLOWING ACROSS THE LAKES SNOW SHOWERS SHOULD CONTINUE TUE INTO TUE NGT. WENT CLOSE TO MAV GUID TEMPS THRU THE PERIOD. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXPECT SCT -SHSN TO CONTINUE THRU A GOOD PART OF WED AS SVRL S/WVS ROTATE AROUND AN UPR LVL TROF EXTNDG BACK ACRS GRT LKS FROM THE POLAR VORTEX. LO LVL WIND FIELDS WILL SLOWLY VEER TO W/NW WITH LK EFFECT SNOW BANDS DVLPG OFF OF LK MICHIGAN AND DROPPING INTO FCST AREA. CONTINUING HI CHC POPS THRU THIS PERIOD...WITH POTENTIAL FOR SOME LIGHT SNOW ACCUMULATIONS OF A FEW INCHES WHERE SNOW BANDS ARE HEAVIER AND MORE PERSISTENT. COLDEST NIGHT SHOULD BE WED NIGHT AS SKIES BEGIN TO CLR WITH HI PRES BUILDING IN...AS TEMPS MAY DROP BELOW 10F. UPR RIDGE THEN BUILDS INTO REGION AS STRONG SFC HI PASSES TO THE SOUTH OF THE REGION. SRLY FLO WILL DVLP BY FRI ON BACK SIDE OF SFC HI...BRINGING A GRADUAL WARMING TREND INTO THE WEEKEND. SFC LO WILL PASS TO NW OF THE REGION FRI NIGHT AND SAT...AND MAY BRING SOME LIGHT PRECIP TO THE FCST AREA. MODEL CONSENSUS CONTINUING TO SHOW THAT WARMING TREND WILL CONTINUE BEYOND THE EXTENDED WITH STRONG UPR RIDGE ANCHORED TO SE OF REGION. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... PLENTY OF CLOUDS STREAMING THRU REGION AHEAD OF MID LVL S/WV. S/WV WILL LIFT INTO GRT LKS THIS EVNG...POSSIBLY PRODUCING A FEW FLURRIES AT KDAY. CURRENT RUC ANALYSIS INDCG MODEL SEEMS TO HAVE THE BEST HANDLE ON BNDRY LYR MOISTURE FOR THE AFTN HOURS. DRIER LO LVL AIR COURTESY OF E/SE FLO HAS PUSHED MUCH OF THE MVFR SC WEST OF THE TERMINALS INTO INDIANA. THIS SHOULD HOLD FOR MUCH OF THE REST OF THE AFTN BEFORE DEEPER BNDRY LYR MOISTURE SPREADS BACK IN AS S/WV PASSES TO THE NW. KCVG/KLUK SHOULD BE MAINLY SPARED OF THE BKN MVFR DECK...BUT EXPECT IT WILL AFFECT NORTHERN TERMINALS DURING THE EVNG. WEAK SFC HI PRES RIDGE WILL BUILD INTO THE OH VLY LATE TONIGHT...AND SHOULD HELP SCATTER OUT THE LOWER CLOUDS DURING THE SECOND HALF OF THE OVERNIGHT. EXCEPTION WILL BE IN CNTRL OH WHERE MODEL SOUNDINGS INDCG MVFR CIGS MAY HOLD ALL NIGHT. MID LVL CLOUDS WILL QUICKLY BEGIN TO SPREAD BACK INTO THE FCST AREA FROM THE WEST DURING THE LATE MRNG MONDAY IN ADVANCE OF THE NEXT SYSTEM TO AFFECT REGION MON EVNG. VRB WINDS THIS AFTN WILL VEER TO S/SW TONIGHT BEHIND THE S/WV. OUTLOOK...MVFR/IFR CIGS/VSBYS POSSIBLE MONDAY NIGHT INTO WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...SITES NEAR TERM...RYAN SHORT TERM...SITES LONG TERM...RYAN AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1052 AM EST SAT DEC 29 2007 .SYNOPSIS... AS LOW PRESSURE PULLS AWAY...HIGH PRESSURE WILL GRADUALLY BUILD INTO THE OHIO VALLEY TODAY. A WEAK UPPER LEVEL DISTURBANCE WILL SWING ACROSS THE NORTHERN PORTIONS OF THE REGION ON SUNDAY...THEN A STRONG COLD FRONT WILL PUSH ACROSS THE REGION MONDAY NIGHT...USHERING IN MUCH COLDER AIR. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MSTLY CLR SKIES OVER SE FCST AREA IN DRY SLOT THIS MRNG. MVFR SC DECK THOUGH FILLING BACK IN ACRS WESTERN FCST AREA...AND SHOULD CONTINUE TO OVERSPREAD MUCH OF THE FCST AREA NORTH OF THE OHIO RIVER FOR THE BETTER PART OF THE AFTN. 12Z RUC/NAM BOTH INDCG DVLPG LO LVL INVERSION WHICH REALLY DOES NOT BEGIN TO BREAK UP UNTIL LATE AFTN AS SFC HI PRES BUILDS INTO THE REGION FROM SW. HAVE ADJUSTED TO MSTLY CLDY SKIES FOR MUCH OF THE AFTN AS A RESULT. WILL GO PTLY SUNNY WHERE CLOUDS SHOULD REMAIN MORE SCATTERED ACRS NRN KY AND FAR SE FCST AREA. LOWERED AFTN HIGHS ACRS NRN 1/2 FCST AREA AS TEMPS WILL PROBABLY STRUGGLE TO CLIMB MUCH FURTHER THAN 5-6 DEG DUE TO PRESENCE OF SC DECK. FURTHER SOUTH WHERE SUN HAS BEEN REALIZED THIS MRNG AND TEMPS HAVE CLIMBED INTO THE L40S...BUMPED UP TEMPS A FEW DEG FROM PREV FCST. ZONE AND GRID FCST UPDATES ALREADY OUT. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... HIGH PRESSURE BUILDS ACROSS THE REGION TONIGHT. HIGH CLOUDS WILL AFFECT THE REGION IN FAST H5 FLOW. MODELS SWING AN H5 S/W ACROSS THE OHIO VALLEY ON SUN. CONSENSUS OF MODELS INDICATES THAT SOME LIGHT PCPN WILL BE PRODUCED ACROSS THE REGION. THE NAM IS THE OUTLIER...LEAVING THE REGION DRY. ADDED A 20 POPS TO THE NW 1/3 OF THE FA. CLIPPER DIVES THRU THE LAKES ON MONDAY...PUSHING CDFNT INTO ERN INDIANA BY END OF PERIOD. AHEAD OF FNT...MODELS ARE PRINTING OFF SOME LIGHT QPF. GENERALLY WENT CLOSE TO THE WARMER MAV TEMPS THRU THE PERIOD. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... ARCTIC FRONT PUSH THRU THE FA MONDAY NIGHT. AS IT DOES THICKNESSES DROP RAPIDLY AND RAIN WILL CHANCE TO SNOW SHOWERS. UPPED POPS TO LIKELY. WITH STRONG CAA ACROSS LAKES DONT SEE WHY THERE WOULDNT BE GOOD COVERAGE IN THE SNOW SHOWERS. STRONG NW CAA CONTINUES INTO TUE AND WED. WAS TEMPTED IN GOING LIKELY WITH THE SNOW SHOWERS...BUT JUST KEPT THINGS IN THE HIGH CHANCE RANGE. HIGH PRESSURE BUILDS IN THU CUTTING OF THE CAA. KEPT TEMPS CLOSE TO PREVIOUS NUMBERS...WHICH WERE A LITTLE COOLER THAN THE NEW MEX MOS. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... STRATUS DECK AOB 2KFT NOTED TO BE JUST NW OF KDAY. SCT-BKN DECK 4-5KFT ALONG AND SE OF I-71 CORRIDOR SHOULD COALESCE BACK INTO A STRATUS DECK AS SUNLIGHT HITS IT AND COMBINES WITH CONTINUED H8 CAA EARLY THIS MORNING. THIS SC DECK WILL LIFT THROUGH LATE AFTERNOON AND THEN BREAK UP WITH THE LOSS OF DAYTIME HEATING. SERN 1/2 OF FCST AREA MAY BE TOUGH TO GET THE SC DECK INTO THE MVFR RANGE FOR AN EXTENDED PERIOD OF TIME TODAY. BELIEVE THAT THERE WILL BE ENOUGH LLVL MOISTURE TO INTERACT WITH THE INSOLATION AND CAA TO HAVE CIGS WITHIN A FEW HUNDRED FEET OF THE 3KFT CUTOFF BTWN VFR AND MVFR. HAVE NOTED A DISTINCT CUTOFF IN THE LOWER STRATUS DECK WHERE A WNW COMPONENT OF THE SFC WINDS ARE BRINGING IN THE COOLER LLVL AIR. WSW INFLUENCE IN THE I-71 CORRIDOR WILL LIKELY BREAK UP QUICKLY THIS MORNING AS THE HIGH BUILDS TO THE SW AND THE FLOW TURNS TO HAVE A NRLY VS SRLY COMPONENT. NAM12 HAS THIS NRLY COMPONENT OVER WRN 2/3 OF CWA BY 15Z AND A CORRELATING INCREASE IN 925 RH. GENERALLY EXPECTING MVFR TO IFR CIGS THROUGH THE DAY TO BREAK UP THIS EVENING. OUTLOOK...MVFR CIGS AND VSBYS ARE POSSIBLE LATE MONDAY INTO TUESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...SITES NEAR TERM...RYAN SHORT TERM...SITES LONG TERM...SITES AVIATION...FRANKS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 115 PM EST SUN DEC 30 2007 .SYNOPSIS... LOW PRESSURE WILL MOVE OFF THE MID ATLANTIC COAST TONIGHT...AS WEAK HIGH PRESSURE CONTROLS OUR WEATHER THROUGH MONDAY NIGHT. A STRONG COLD FRONT WILL CROSS OUR REGION EARLY TUESDAY WITH SHARPLY COLDER TEMPERATURES THROUGH THURSDAY AND SIGNIFICANT MOUNTAIN SNOW ALONG THE TENNESSEE BORDER. AS STRONG HIGH PRESSURE MOVES OFF THE ATLANTIC COAST NEXT WEEKEND...EXPECT TEMPERATURES TO WARM. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AT 16Z...CONVERGENCE ALONG THE FRONT REMAINS OVER THE EASTERN CWA BORDER AND HAS MOVED VERY LITTLE OVER THE PAST COUPLE OF HRS. IT APPEARS THAT THE MILD AND HUMID AIR MASS OVER THE MIDLANDS AND COASTAL PLAINS WILL NOT ADVANCE NW INTO THE FORECAST AREA. I WILL CODE WIDESPREAD PRECIPITATION AS RA AND ONLY MENTION ISO TS OVER THE EASTERN TIER OF COUNTIES THIS AFTERNOON. OTHERWISE...COVERAGE SHOULD REMAIN UNCHANGED THROUGH 21Z. AFTER 21Z...DRY AIR SHOULD SLOWLY ADVANCE EAST ACROSS THE MTNS AND FOOTHILLS. CATE COVERAGE SHOULD REMAIN OVER THE I-77 CORRIDOR UNTIL 0Z. I WILL POPULATE HRLY AND DWPTS TEMPS WITH OBS AND RUC 13 DATA...RESULTING TO STEADY TEMPS UNTIL EVENING. OTHERWISE...THE CURRENT FORECAST IS IN GOOD SHAPE. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... AS OF 230 AM EDT SUNDAY...UPPER LEVEL FLOW BRIEFLY FLATTENS OUT ACROSS THE EASTERN CONUS MONDAY...AS A SFC LOW DEEPENS AND TRACK NORTHEAST OFF THE EAST COAST. AS THE LOW DEPARTS...POP DECREASES RAPIDLY FROM W TO E BY AROUND 2 AM MONDAY. MODEL T-SECTIONS SHOW THE WHOLE COLUMN OVER THE CWFA DRYING OUT...SO SUNNY SKIES ARE EXPECTED MONDAY UNDER WSW FLOW. THIS WILL ALLOW MAX TEMPS TO BE WELL ABOVE NORMAL (AROUND 60 PIEDMONT AND 50S MTNS). MONDAY NIGHT...LOW PRESSURE DEVELOPS OVER THE GREAT LAKES...AS A POTENT SHORTWAVE CROSSES THE MIDWEST. LOW LEVEL FLOW OUT AHEAD OF IT WILL BE OUT OF THE SOUTH AND SW...HOWEVER DRY. SO SKIES WILL BE GENERALLY CLEAR...BUT I HAVE MIN TEMPS ABOVE MOS CONSENSUS...DUE TO THE WAA FLOW. A STRONG COLD FRONT ASSOCIATED WITH THE GREAT LAKES LOW IS PROGGED TO ENTER THE MTNS BY AROUND 06Z TUESDAY. SOME LOW LEVEL MOISTURE IS SHOWN IN THE MODELS WITH THIS...AND UPSLOPE AREAS MAY SEE SOME ISO/SCT SHOWERS BEFORE DAWN TUESDAY. MODEL THICKNESSES AND P-TYPE NOMOGRAM INDICATE THAT ANY PRECIP WILL LIKELY BE ALL SNOW. TUESDAY...STRONG LOW LEVEL CAA CONTINUES ACROSS THE CWFA BEHIND THE FRONT...AS LOW PRESSURE TO OUR NE DEEPENS AND A STRONG SFC HIGH BUILDS INTO THE GREAT PLAINS. BOTH THE NAM AND GFS SHOW A LULL IN THE 850MB WINDS (GENERALLY AFTER THE INITIAL SHORTWAVE PASSES BY). WITH THIS IN MIND...I DID NOT INCREASE POP FOR THIS PERIOD (LOW-MID CHC). 850 TEMPS CONTINUE TO FALL DURING THE DAY ON TUESDAY...AND ETA/GFS BUFKIT SOUNDINGS INDICATE THAT ALL PRECIP IN THE MTNS WILL PROBABLY BE ALL SNOW. MOS TEMPS SEEM TOO HIGH IN THE HIGHER TERRAIN. FOR NOW...I WENT WITH MET TEMPS FOR MAX TUESDAY IN THE MTNS WITH A BLEND ELSEWHERE. TUESDAY NIGHT...A SECOND POTENT SHORT WAVE DIVES SOUTH OUT OF CANADA...WITH DPVA DEVELOPING ACROSS THE MTNS STARTING 00Z WEDNESDAY. IN ADDITION TO THE ADDED LIFT...LOW LEVEL TRAJECTORIES SHOW A GREAT LAKES CONNECTION WITH EVEN SOME SMALL SBCAPE. SO POP INCREASES TO LIKELY ALONG THE TN BORDER (WITH THE HIGHEST SNOW ACCUMULATIONS EXPECTED). THIS IS THE MOST LIKELY TIME THAT SOME SNOW SHOWERS COULD BREAK CONTAINMENT...BUT I DID NOT ADD THIS TO THE GRIDS AT THIS TIME. OVERALL...MIN TEMPS PLUMMET INTO THE SINGLE DIGITS AND TEENS IN THE MTNS (LOWER TO MID 20S PIEDMONT). WIND CHILLS WILL APPROACH ADVISORY CRITERIA AS WELL. WEDNESDAY...NW FLOW SNOW EVENT BEGINS TO WIND DOWN...AS LOW LEVELS BEGIN TO DRY OUT AND UPSLOPE FLOW WEAKENS. THE GFS SEEMS TO CUT OFF PRECIP ABRUPTLY BY 12Z. HOWEVER...I THINK THIS MAY BE TOO FAST...AND HAVE KEPT CHC POP IN THROUGH THE AFTN. WITH LOW LEVEL THICKNESSES VERY COLD...MAX TEMPS WILL BE 5-10 DEGREES BELOW NORMAL (EVEN MORE IN THE MTNS). && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 300 AM SATURDAY...LARGE DOME OF STRONG HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE EASTERN PORTION OF THE UNITED STATES ON THURSDAY. ATMOSPHERE WILL DRY OUT AND REMAIN STABLE THROUGH THE WEEKEND AS THE RIDGE MOVES EAST OVER THE ATLANTIC. TEMPS AND LOW LEVEL THICKNESS VALUES WILL SLOWLY INCREASE AS TEMPS APPROACH THE 60 DEGREE MARK...WHILE LOW LEVEL FLOW BECOMES MORE SOUTHERLY AND UNIFORM OVER THE REGION BY LATE IN THE WEEKEND. BOTH NEW RUNS OF THE GFS AND ECMWF ARE COMPARABLE WITH REGARDS TO THE STRENGTH OF THE RIDGE AND ITS LONGEVITY...HOWEVER THE EUROPEAN MODEL DOES WEAKEN THE SOUTHERLY FLOW LATE SUNDAY AND MONDAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AT 1810Z...RADAR DETECTED WIDESPREAD RAINFALL ACROSS THE FOOTHILLS AND PIEDMONT WITH PATCHES OF LIGHT SHOWERS OVER THE MTNS. SFC OBS INDICATE THAT CONDITIONS RANGE FROM IFR TO MVFR UNDER THE PRECIPITATION SHIELD TO IFR-LIFR WEST OF THE RAINFALL. FORECAST SOUNDINGS INDICATE THAT DRYING THROUGH THE ATMOSPHERE MAY NOT OCCUR UNTIL 0-3Z. THEREFORE...CONDITIONS MAY REMAIN LIMITED ACROSS THE WESTERN CAROLINAS UNTIL THIS EVENING. THE ATMOSPHERE WILL CONTINUE TO DRY FROM THE TOP DOWN...POSSIBLY RESULTING IN NO CEILING BY 6Z. BY SUNRISE...WINDS MAY SHIFT TO THE SOUTH-SOUTHWEST AND SKY AND VIS WILL BE UNLIMITED. AVIATION OUTLOOK...VFR CONDITIONS MONDAY AND MONDAY NIGHT. GUSTY NORTHWEST WINDS WILL ARRIVE TUESDAY...AND MOUNTAIN SNOW SHOWERS AND ASSOCIATED RESTRICTIONS MAY AFFECT KAVL TUESDAY NIGHT THROUGH WEDNESDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...ARK NEAR TERM...NED SHORT TERM...ARK LONG TERM...JPT AVIATION...NED sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1133 AM EST SUN DEC 30 2007 .SYNOPSIS... LOW PRESSURE WILL DEVELOP OVER THE COASTAL PLAIN OF THE CAROLINAS THIS AFTERNOON...THEN TRACK NORTHEAST ALONG THE EAST COAST TONIGHT. HIGH PRESSURE BRIEFLY SETTLES IN MONDAY...BEFORE A STRONG COLD FRONT TRACKS THROUGH THE SOUTHEAST STATES BY EARLY TUESDAY. COLD HIGH PRESSURE WILL SETTLE IN FOR MUCH OF THE WEEK WITH A DEEP UPPER LEVEL TROUGH PASSING THROUGH OUR REGION WEDNESDAY THROUGH FRIDAY. SIGNIFICANT SNOW IS EXPECTED IN THE MOUNTAINS NEAR THE TENNESSEE BORDER TUESDAY MORNING THROUGH WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AT 16Z...CONVERGENCE ALONG THE FRONT REMAINS OVER THE EASTERN CWA BORDER AND HAS MOVED VERY LITTLE OVER THE PAST COUPLE OF HRS. IT APPEARS THAT THE MILD AND HUMID AIR MASS OVER THE MIDLANDS AND COASTAL PLAINS WILL NOT ADVANCE NW INTO THE FORECAST AREA. I WILL CODE WIDESPREAD PRECIPITATION AS RA AND ONLY MENTION ISO TS OVER THE EASTERN TIER OF COUNTIES THIS AFTERNOON. OTHERWISE...COVERAGE SHOULD REMAIN UNCHANGED THROUGH 21Z. AFTER 21Z...DRY AIR SHOULD SLOWLY ADVANCE EAST ACROSS THE MTNS AND FOOTHILLS. CATE COVERAGE SHOULD REMAIN OVER THE I-77 CORRIDOR UNTIL 0Z. I WILL POPULATE HRLY AND DWPTS TEMPS WITH OBS AND RUC 13 DATA...RESULTING TO STEADY TEMPS UNTIL EVENING. OTHERWISE...THE CURRENT FORECAST IS IN GOOD SHAPE. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... AS OF 230 AM EDT SUNDAY...UPPER LEVEL FLOW BRIEFLY FLATTENS OUT ACROSS THE EASTERN CONUS MONDAY...AS A SFC LOW DEEPENS AND TRACK NORTHEAST OFF THE EAST COAST. AS THE LOW DEPARTS...POP DECREASES RAPIDLY FROM W TO E BY AROUND 2 AM MONDAY. MODEL T-SECTIONS SHOW THE WHOLE COLUMN OVER THE CWFA DRYING OUT...SO SUNNY SKIES ARE EXPECTED MONDAY UNDER WSW FLOW. THIS WILL ALLOW MAX TEMPS TO BE WELL ABOVE NORMAL (AROUND 60 PIEDMONT AND 50S MTNS). MONDAY NIGHT...LOW PRESSURE DEVELOPS OVER THE GREAT LAKES...AS A POTENT SHORTWAVE CROSSES THE MIDWEST. LOW LEVEL FLOW OUT AHEAD OF IT WILL BE OUT OF THE SOUTH AND SW...HOWEVER DRY. SO SKIES WILL BE GENERALLY CLEAR...BUT I HAVE MIN TEMPS ABOVE MOS CONSENSUS...DUE TO THE WAA FLOW. A STRONG COLD FRONT ASSOCIATED WITH THE GREAT LAKES LOW IS PROGGED TO ENTER THE MTNS BY AROUND 06Z TUESDAY. SOME LOW LEVEL MOISTURE IS SHOWN IN THE MODELS WITH THIS...AND UPSLOPE AREAS MAY SEE SOME ISO/SCT SHOWERS BEFORE DAWN TUESDAY. MODEL THICKNESSES AND P-TYPE NOMOGRAM INDICATE THAT ANY PRECIP WILL LIKELY BE ALL SNOW. TUESDAY...STRONG LOW LEVEL CAA CONTINUES ACROSS THE CWFA BEHIND THE FRONT...AS LOW PRESSURE TO OUR NE DEEPENS AND A STRONG SFC HIGH BUILDS INTO THE GREAT PLAINS. BOTH THE NAM AND GFS SHOW A LULL IN THE 850MB WINDS (GENERALLY AFTER THE INITIAL SHORTWAVE PASSES BY). WITH THIS IN MIND...I DID NOT INCREASE POP FOR THIS PERIOD (LOW-MID CHC). 850 TEMPS CONTINUE TO FALL DURING THE DAY ON TUESDAY...AND ETA/GFS BUFKIT SOUNDINGS INDICATE THAT ALL PRECIP IN THE MTNS WILL PROBABLY BE ALL SNOW. MOS TEMPS SEEM TOO HIGH IN THE HIGHER TERRAIN. FOR NOW...I WENT WITH MET TEMPS FOR MAX TUESDAY IN THE MTNS WITH A BLEND ELSEWHERE. TUESDAY NIGHT...A SECOND POTENT SHORT WAVE DIVES SOUTH OUT OF CANADA...WITH DPVA DEVELOPING ACROSS THE MTNS STARTING 00Z WEDNESDAY. IN ADDITION TO THE ADDED LIFT...LOW LEVEL TRAJECTORIES SHOW A GREAT LAKES CONNECTION WITH EVEN SOME SMALL SBCAPE. SO POP INCREASES TO LIKELY ALONG THE TN BORDER (WITH THE HIGHEST SNOW ACCUMULATIONS EXPECTED). THIS IS THE MOST LIKELY TIME THAT SOME SNOW SHOWERS COULD BREAK CONTAINMENT...BUT I DID NOT ADD THIS TO THE GRIDS AT THIS TIME. OVERALL...MIN TEMPS PLUMMET INTO THE SINGLE DIGITS AND TEENS IN THE MTNS (LOWER TO MID 20S PIEDMONT). WIND CHILLS WILL APPROACH ADVISORY CRITERIA AS WELL. WEDNESDAY...NW FLOW SNOW EVENT BEGINS TO WIND DOWN...AS LOW LEVELS BEGIN TO DRY OUT AND UPSLOPE FLOW WEAKENS. THE GFS SEEMS TO CUT OFF PRECIP ABRUPTLY BY 12Z. HOWEVER...I THINK THIS MAY BE TOO FAST...AND HAVE KEPT CHC POP IN THROUGH THE AFTN. WITH LOW LEVEL THICKNESSES VERY COLD...MAX TEMPS WILL BE 5-10 DEGREES BELOW NORMAL (EVEN MORE IN THE MTNS). && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... AS OF 300 AM SATURDAY...LARGE DOME OF STRONG HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE EASTERN PORTION OF THE UNITED STATES ON THURSDAY. ATMOSPHERE WILL DRY OUT AND REMAIN STABLE THROUGH THE WEEKEND AS THE RIDGE MOVES EAST OVER THE ATLANTIC. TEMPS AND LOW LEVEL THICKNESS VALUES WILL SLOWLY INCREASE AS TEMPS APPROACH THE 60 DEGREE MARK...WHILE LOW LEVEL FLOW BECOMES MORE SOUTHERLY AND UNIFORM OVER THE REGION BY LATE IN THE WEEKEND. BOTH NEW RUNS OF THE GFS AND ECMWF ARE COMPARABLE WITH REGARDS TO THE STRENGTH OF THE RIDGE AND ITS LONGEVITY...HOWEVER THE EUROPEAN MODEL DOES WEAKEN THE SOUTHERLY FLOW LATE SUNDAY AND MONDAY. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AVIATION FORECAST A BIT LIKE TRYING TO HIT A MOVING TARGET AT THE CURRENT TIME...WITH LARGE PRECIP SHIELD ADVANCING QUICKLY ACROSS N GA AND INTO THE WRN CAROLINAS AHEAD OF DEVELOPING SURFACE WAVE. THE TAFS WILL GO OUT WITH A TREND TOWARD LOW MVFR CEILINGS AND MVFR VISBY BY 13Z TO 14Z FROM SW TO NE AND AMENDMENTS WILL BE MADE AS NECESSARY. IFR CEILINGS APPEAR LESS LIKELY DURING THE DAYLIGHT BUT A TEMPO WILL STILL BE INCLUDED THROUGH NOON AT THE SITES OUTSIDE THE MOUNTAINS. THE PRECIP SHOULD MOVE OUT LATER IN THE AFTERNOON WITH CONDITIONS IMPROVING TO VFR IN THE 23Z TO 02Z TIME FRAME. A PERIOD OF MVFR FOG CANNOT BE RULED OUT THIS EVENING GIVEN THE AMT OF RAINFALL EXPECTED...BUT THIS DETAIL WILL NOT BE INCLUDED YET. CLEARING SHOULD HAPPEN AFTER MIDNIGHT AS THE LOW PULLS AWAY. AVIATION OUTLOOK...VFR CONDITIONS ARE EXPECTED MONDAY AND MONDAY NIGHT. GUSTY NORTHWEST WINDS WILL ARRIVE TUESDAY...AND MOUNTAIN SNOW SHOWERS AND ASSOCIATED RESTRICTIONS MAY AFFECT KAVL TUESDAY NIGHT THROUGH WEDNESDAY. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...ARK NEAR TERM...NED SHORT TERM...ARK LONG TERM...JPT AVIATION...PM sc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 826 PM CST SAT DEC 29 2007 .DISCUSSION... MAIN CONCERN IS THE FOG AND LOW CLOUDS AND THE EFFECTS THIS WILL HAVE ON TEMPERATURES. APPEARS THAT THE BACK EDGE OF THE STRATUS HAS NOW MOVED EAST OF THE JAMES VALLEY AND IS VERY CLOSE TO I90. IN ADDITION...WEAK SOUTHEAST FLOW ACROSS THE AREA IS HELPING TO ADVECT COLDER AIR UNDER THE CLOUDS SO THAT PLACES LIKE MHE...FSD AND SPW HAVE ALREADY FALLEN SEVERAL DEGREES. EXPECT THAT THE LOW CLOUDS WILL RETREAT A BIT MORE TONIGHT AND GENERALLY BE OVER SW MN AND EAST CENTRAL SD. JUST TO THE SOUTH OF THE CLOUDS THERE WILL BE A BAND OF FOG WITH VSBYS BELOW 1 SM AT TIMES WHERE DEEP ENOUGH MOISTURE RESIDES AND COOLING OCCURS. INTERESTINGLY...WITH TEMPS BELOW 14F/-10C...SOME ICE CRYSTALS/SNOW ARE FALLING OUT OF THE FOG AROUND FSD AND WOULDN`T BE SURPRISED IF THERE ARE VERY LOCALIZED FLURRIES IN THE DENSER FOG ONCE TEMPS FALL TO NEAR 10F/-12C. OTHERWISE...EXPECT SKIES MOSTLY CLEAR WITH SOME LIGHT PATCHY FOG SOUTH OF I90. THIS WILL REALLY SET UP A CONTRAST IN TEMPERATURES. ALREADY YANKTON...VERMILLION...AND A LARGE PORTION OF NW IOWA IS BELOW 10F WITH DEW POINTS NEAR ZERO. WITH ONLY LIGHT SE FLOW...SEE NO REASON TEMPS WON`T FALL TO NEAR ZERO WITH BELOW ZERO IN RIVER VALLEYS AND OTHER DRAINAGE AREAS. ALSO EXPECT THAT ALONG I90 FROM 9V9 TO LYV AS WELL AS THE NORTHERN TIER OF COUNTIES IN NW IA...TEMPS WILL FALL INTO THE SINGLE DIGITS. ONLY PORTIONS OF SW MN WILL LIKELY STAY...AS WELL AS AROUND 9V9...WILL STAY ABOVE 10 F EITHER BECAUSE OF LOW CLODUS OR BECAUSE OF INCREASING SE FLOW AIDING IN SOME MIXING. DID SLOW THE INCREASE IN CLOUDS TONIGHT IN THE SRN CWA ALTHOUGH THE 18Z NAM SUGGESTS THAT CLOUDS SHOULD BEGIN TO REFORM IN NW IA TOWARD DAWN. NEW GRIDS AND PFM AVAILABLE AND UPDATED ZFP SHOULD BE AVAILABLE BY 0240Z. && .AVIATION... WIDE VARIATION IN CEILINGS AND VSBYS ACROSS CWA THIS EVENING. LOW CLDS AND FOG CLEARED OUT OF THE KSUX AREA THIS AFTERNOON...AND HAVE SINCE CLEARED KHON THIS EVENING. IFR CIGS AND VSBYS AT KFSD AT 02Z...BUT LOW LEVEL MOISTURE NOW PRECIPITATING OUT AS LIGHT SNOW IN THE FSD AREA. SO APPEARS LIFR CONDS PROBABLY WILL NOT BLANKET THE TAF SITES OVERNIGHT. RATHER...ONCE MID CLDS MOVE THRU...WILL HAVE POTENTIAL FOR RADITATION FOG AFTER 09Z AT KHON AND PROBABLY CLOSER TO 11Z KSUX AREA...WITH VSBYS DOWN TO AROUND 2 MILES IN BR. STRATUS MAY FORM AROUND SUNRISE AT THESE LOCATIONS...AND IF IT DOES...WILL BE SLOW TO MIX OUT WITH STRONG INVERSION AND WEAK MIXING GRADIENT THRU MID DAY SUNDAY. KFSD HAS BEST CHANCE FOR CIGS AND VSBY IN THE IFR CATEGORY THRU SUNDAY...BUT WILL LIKELY SEE A PERIOD LATER THIS EVENING WHERE KFSD BREAKS OUT TO VFR FOR AWHILE BEFORE GOING BACK DOWN. && .PREV DISCUSSION... A COUPLE CHALLENGES FOR THE OVERNIGHT PERIOD. FIRST IS WITH THE EXTENT OF STRATUS CLEARING IN THE SRN AND WRN CWA. ACROSS NW IW...STATUS/FOG HAVE BEEN SLOWLY LIFTING NWRN AT AROUND 6 KTS THROUGH THE DAY...BUT ACCORDING TO RUC AND NAM 950 MB RH FIELDS... THE CLEARING SHOULD CHECK UP BY EARLY THIS EVENING...WITH THE NRN EXTENT OF CLEARING ON A E/W LINE ROUGHLY AROUND SPENCER IOWA. S OF THIS AREA...TEMPERATURES WILL RAPIDLY DROP THIS EVENING AND FOG WILL LIKELY FORM...AND COULD BECOME DENSE IN PLACES BY LATE THIS EVENING. TOUGH TO TELL THE AMOUNT OF CLEARING ALONG THE WRN EDGE OF THE STRATUS IN CENTRAL SD BASED ON SATELLITE...BUT DOES APPEAR CLEARING LINE IS ALMOST TO MHE. WILL KEEP TEMPERATURES NEAR STEADY WHERE STRATUS IS EXPECTED TO CONTINUE AND DROP TEMPERATURES QUITE A BIT ELSEWHERE. SHOULD SEE A 25 TO 30 DEGREE TEMPERATURE DIFFERENCE IN LOWS FROM CLEAR SKIES TO PLACES WITH CLOUD COVER. EXPECTING FOG ACROSS MOST OF THE CWA...EVEN WHERE STRATUS HOLDS COULD SEE CEILINGS DROP TO THE SFC LATER TONIGHT...ESPECIALLY SINCE WARM AIR ADVECTION WILL PERSIST. THERE IS THE POTENTIAL FOR DENSE FOG IN THESE AREAS AS WELL...WITH VISIBILITIES REDUCED TO LESS THAN ONE QUARTER MILE. ACTUALLY A THIN BAND OF QUARTER MILE VISIBILITIES HAS CONTINUED THROUGH THE DAY OF OVER PORTIONS OF NW IA...WHILE SLOWLY DRIFTING N. ONCE DAYTIME HEATING IS NOT LONGER A FACTOR...SHOULD SEE VISIBILITIES IN THIS AREA DROP...AND EVENTUALLY SPREAD TO ADJACENT AREAS. SUNDAY WILL SEE MORE CONCERNS WITH STRATUS AND FOG IN THE MORNING...BUT THIS SHOULD BE THE LAST DAY WITH FOG ISSUES AS A STRONG COLD FRONT IS POISED TO MOVE THROUGH ON MONDAY MORNING. WILL BACK OFF ON POPS UNTIL SUNDAY NIGHT AS SUNDAY LOOKS A LITTLE DRY IN THE MID LEVELS AND EVEN THOUGH UPPER LEVEL FORCING SPRINTS INTO THE SOUTHERN CWA BY ABOUT 21Z...WE SHOULD HAVE SOME DRY AIR TO OVERCOME. FOR THE SYSTEM SUNDAY NIGHT INTO MONDAY MORNING...STARTING TO LOOK LIKE BETTER FORCUS COULD END UP A LITTLE FARTHER SOUTH...POSSIBLY NEAR THE MISSOURI RIVER. BOTH THE LATEST NAM AND GFS AGREE THAT BEST UPPER LEVEL SUPPORT VIA THE 300-500MB DIV Q AND PV ANOMALY PLACEMENT SUPPORT THE SOUTHERN CWA AND WITH A WEAK THERMAL STRUCTURE TO THE SYSTEM...MUCH OF THE PRECIPITATION PROCESS SHOULD BE DRIVEN BY THE UPPER LEVELS. BEST THERMAL BANDING APPEARS TO OCCUR FROM ABOUT 650-600MB AND THIS BOUNDARY LAYS OUT WEST TO EAST ACROSS FAR SOUTHERN CWA SUNDAY NIGHT AS JET STREAK PASSES SOUTH. ALSO OF INTEREST IS THAT THIS SYSTEM DOES POSSES A LITTLE INSTABILITY WITH 700-500MB LAPSE RATES RUNNING ABOUT 7-7.5 C/KM AND 750MB LI`S RUNNING RIGHT AROUND 2-3 C. REGARDLESS...WILL NOT INCREASE POPS AS PLACEMENT OF WHAT WILL LIKELY BE A RELATIVELY SMALL BAND STILL UNCERTAIN. WILL LEAVE A SMALL POP IN FOR MONDAY NIGHT AS FINAL LITTLE CHUNK OF ENERGY SKIRTS BY AS COLDEST AIR SINKS SOUTH. ALSO SOME CONCERN ABOUT BLOWING SNOW WITH FLUFFY STUFF ALREADY ON THE GROUND AND WINDS INCREASING TO 20 TO 30 MPH...BUT AT THIS TIME...WITH WINDS GENERALLY BELOW 30 MPH...A BLOWING SNOW ADVISORY DOES NOT SEEM IMMENENT. AS FOR TEMPERATURES...LOTS OF NON-DIURNAL TO WORK WITH WITH LITTLE OR NO FALL WITHIN STRATUS AND RAPID FALLS OUTSIDE. WILL ALSO SEE COLD AIR SINKING IN ON MONDAY WITH HIGHS EARLY IN THE DAY THEN FALLING. WENT FOR A VERY QUICK EVENING DROP ON TUESDAY NIGHT WITH 1045MB ARCTIC HIGH AND HAVE COME IN ABOUT 5 TO 10 DEGREES COLDER THAN GUIDANCE FROM 0Z-6Z. IN THE LATTER PERIODS(WED-SAT)...TAIL END OF SOUTHEAST DIVING WAVE WILL HAVE A COLD HIGH PRESSURE AT THE SURFACE IN PLACE WEDNESDAY MORNING OVER THE EXTREME EASTERN PART OF THE CWA. THIS WILL HAVE MOST LOCATIONS SUB ZERO TO START THE PERIOD...WITH STRONG RIDGING ALOFT AND STRONG SOUTHERLY WINDS DEVELOPING THROUGHOUT THE DAY WEDNESDAY. A WEAK WAVE WILL TRAVERSE THE U.S./CANADIAN BORDER ON THURSDAY...WHICH COULD DRAG A WEAK BACK DOOR COOL FRONT DOWN ON THURSDAY. THIS NOT SHOWING UP IN THE LOW LEVEL THERMAL FIELDS YET AND AT THIS TIME WILL JUST BE SOMETHING TO WATCH FOR. AFTER THIS...WEST COAST TROF PUSHES INTO THE ROCKIES WITH A SERIES OF WEAK WAVES POSSIBLE FRIDAY INTO THE WEEKEND. NOT MUCH TO GRAB A HOLD OF AT THIS TIME...SO WILL NOT ADD ANY PRECIPITATION POTENTIAL. SO...OVERALL...MILD AND DRY IN THE EXTENDED. IN FACT...IF THIS PATTERN DOES VERIFY...WE WOULD HAVE EASILY BEEN IN THE 40S WITH NO SNOW COVER. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$ SCHUMACHER/GH sd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 257 PM CST SAT DEC 29 2007 .DISCUSSION... A COUPLE CHALLENGES FOR THE OVERNIGHT PERIOD. FIRST IS WITH THE EXTENT OF STRATUS CLEARING IN THE SRN AND WRN CWA. ACROSS NW IW...STATUS/FOG HAVE BEEN SLOWLY LIFTING NWRN AT AROUND 6 KTS THROUGH THE DAY...BUT ACCORDING TO RUC AND NAM 950 MB RH FIELDS... THE CLEARING SHOULD CHECK UP BY EARLY THIS EVENING...WITH THE NRN EXTENT OF CLEARING ON A E/W LINE ROUGHLY AROUND SPENCER IOWA. S OF THIS AREA...TEMPERATURES WILL RAPIDLY DROP THIS EVENING AND FOG WILL LIKELY FORM...AND COULD BECOME DENSE IN PLACES BY LATE THIS EVENING. TOUGH TO TELL THE AMOUNT OF CLEARING ALONG THE WRN EDGE OF THE STRATUS IN CENTRAL SD BASED ON SATELLITE...BUT DOES APPEAR CLEARING LINE IS ALMOST TO MHE. WILL KEEP TEMPERATURES NEAR STEADY WHERE STRATUS IS EXPECTED TO CONTINUE AND DROP TEMPERATURES QUITE A BIT ELSEWHERE. SHOULD SEE A 25 TO 30 DEGREE TEMPERATURE DIFFERENCE IN LOWS FROM CLEAR SKIES TO PLACES WITH CLOUD COVER. EXPECTING FOG ACROSS MOST OF THE CWA...EVEN WHERE STRATUS HOLDS COULD SEE CEILINGS DROP TO THE SFC LATER TONIGHT...ESPECIALLY SINCE WARM AIR ADVECTION WILL PERSIST. THERE IS THE POTENTIAL FOR DENSE FOG IN THESE AREAS AS WELL...WITH VISIBILITIES REDUCED TO LESS THAN ONE QUARTER MILE. ACTUALLY A THIN BAND OF QUARTER MILE VISIBILITIES HAS CONTINUED THROUGH THE DAY OF OVER PORTIONS OF NW IA...WHILE SLOWLY DRIFTING N. ONCE DAYTIME HEATING IS NOT LONGER A FACTOR...SHOULD SEE VISIBILITIES IN THIS AREA DROP...AND EVENTUALLY SPREAD TO ADJACENT AREAS. SUNDAY WILL SEE MORE CONCERNS WITH STRATUS AND FOG IN THE MORNING...BUT THIS SHOULD BE THE LAST DAY WITH FOG ISSUES AS A STRONG COLD FRONT IS POISED TO MOVE THROUGH ON MONDAY MORNING. WILL BACK OFF ON POPS UNTIL SUNDAY NIGHT AS SUNDAY LOOKS A LITTLE DRY IN THE MID LEVELS AND EVEN THOUGH UPPER LEVEL FORCING SPRINTS INTO THE SOUTHERN CWA BY ABOUT 21Z...WE SHOULD HAVE SOME DRY AIR TO OVERCOME. FOR THE SYSTEM SUNDAY NIGHT INTO MONDAY MORNING...STARTING TO LOOK LIKE BETTER FORCUS COULD END UP A LITTLE FARTHER SOUTH...POSSIBLY NEAR THE MISSOURI RIVER. BOTH THE LATEST NAM AND GFS AGREE THAT BEST UPPER LEVEL SUPPORT VIA THE 300-500MB DIV Q AND PV ANOMALY PLACEMENT SUPPORT THE SOUTHERN CWA AND WITH A WEAK THERMAL STRUCTURE TO THE SYSTEM...MUCH OF THE PRECIPITATION PROCESS SHOULD BE DRIVEN BY THE UPPER LEVELS. BEST THERMAL BANDING APPEARS TO OCCUR FROM ABOUT 650-600MB AND THIS BOUNDARY LAYS OUT WEST TO EAST ACROSS FAR SOUTHERN CWA SUNDAY NIGHT AS JET STREAK PASSES SOUTH. ALSO OF INTEREST IS THAT THIS SYSTEM DOES POSSES A LITTLE INSTABILITY WITH 700-500MB LAPSE RATES RUNNING ABOUT 7-7.5 C/KM AND 750MB LI`S RUNNING RIGHT AROUND 2-3 C. REGARDLESS...WILL NOT INCREASE POPS AS PLACEMENT OF WHAT WILL LIKELY BE A RELATIVELY SMALL BAND STILL UNCERTAIN. WILL LEAVE A SMALL POP IN FOR MONDAY NIGHT AS FINAL LITTLE CHUNK OF ENERGY SKIRTS BY AS COLDEST AIR SINKS SOUTH. ALSO SOME CONCERN ABOUT BLOWING SNOW WITH FLUFFY STUFF ALREADY ON THE GROUND AND WINDS INCREASING TO 20 TO 30 MPH...BUT AT THIS TIME...WITH WINDS GENERALLY BELOW 30 MPH...A BLOWING SNOW ADVISORY DOES NOT SEEM IMMENENT. AS FOR TEMPERATURES...LOTS OF NON-DIURNAL TO WORK WITH WITH LITTLE OR NO FALL WITHIN STRATUS AND RAPID FALLS OUTSIDE. WILL ALSO SEE COLD AIR SINKING IN ON MONDAY WITH HIGHS EARLY IN THE DAY THEN FALLING. WENT FOR A VERY QUICK EVENING DROP ON TUESDAY NIGHT WITH 1045MB ARCTIC HIGH AND HAVE COME IN ABOUT 5 TO 10 DEGREES COLDER THAN GUIDANCE FROM 0Z-6Z. IN THE LATTER PERIODS(WED-SAT)...TAIL END OF SOUTHEAST DIVING WAVE WILL HAVE A COLD HIGH PRESSURE AT THE SURFACE IN PLACE WEDNESDAY MORNING OVER THE EXTREME EASTERN PART OF THE CWA. THIS WILL HAVE MOST LOCATIONS SUB ZERO TO START THE PERIOD...WITH STRONG RIDGING ALOFT AND STRONG SOUTHERLY WINDS DEVELOPING THROUGHOUT THE DAY WEDNESDAY. A WEAK WAVE WILL TRAVERSE THE U.S./CANADIAN BORDER ON THURSDAY...WHICH COULD DRAG A WEAK BACK DOOR COOL FRONT DOWN ON THURSDAY. THIS NOT SHOWING UP IN THE LOW LEVEL THERMAL FIELDS YET AND AT THIS TIME WILL JUST BE SOMETHING TO WATCH FOR. AFTER THIS...WEST COAST TROF PUSHES INTO THE ROCKIES WITH A SERIES OF WEAK WAVES POSSIBLE FRIDAY INTO THE WEEKEND. NOT MUCH TO GRAB A HOLD OF AT THIS TIME...SO WILL NOT ADD ANY PRECIPITATION POTENTIAL. SO...OVERALL...MILD AND DRY IN THE EXTENDED. IN FACT...IF THIS PATTERN DOES VERIFY...WE WOULD HAVE EASILY BEEN IN THE 40S WITH NO SNOW COVER. && .AVIATION... CEILINGS AND VISIBILITIES WILL BE A PROBLEM TONIGHT AND INTO TOMORROW. LOW CLOUDS HAVE CLEARED AT SUX BUT LIGHT WINDS WILL ALLOW FOR FOG TO FORM AGAIN THIS EVENING. WILL LIKELY SEE VISIBILITIES DROP TO A QUARTER MILE BY LATE THIS EVENING. FOR FSD...LOW STRATUS IS LIKELY TO CONTINUE WITH CEILINGS REMAINING BELOW 1000 FT...AND COULD SEE CEILINGS DROP TO BELOW 300 FT LATER TONIGHT AND VISIBILITIES LESS THAN 1 SM. HON IS MORE QUESTIONABLE AS TO WHETHER OR NOT STRATUS WILL CLEAR THIS EVENING OR NOT...EITHER WAY SHOULD SEE LIFR CONDITIONS BY LATER TONIGHT DUE TO FOG OR STRATUS DRIFTING BACK INTO THE JAMES VALLEY. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...NONE. MN...NONE. NE...NONE. SD...NONE. && $$ LIEBL/08 sd AREA FORECAST DISCUSSION...AVIATION UPDATED NATIONAL WEATHER SERVICE SALT LAKE CITY UT 352 PM AM MST SUN DEC 30 2007 .SYNOPSIS...A COLD FRONT WILL SWEEP THROUGH ALL OF UTAH THIS EVENING WITH VERY COLD AIR BEHIND IT. HIGH PRESSURE WILL BUILD OVER THE AREA MONDAY THROUGH MID WEEK. THIS WILL BRING A STRONG WARMING TREND TO THE MOUNTAINS ON TUESDAY AND WEDNESDAY WHILE INVERSIONS STRENGTHEN IN THE VALLEYS. A SERIES OF PACIFIC STORMS WILL RETURN FOR LATE IN THE WEEK. && .DISCUSSION...SURFACE COLD FRONT HAS SHIFTED SOUTH INTO CENTRAL UTAH WITH MID LEVEL BAROCLINIC ZONE LAGGING BEHIND. RADAR TREND IS DECREASING AND SHIFTING SLIGHTLY SOUTHWARD INTO CENTRAL MOUNTAINS. SNOW WAS HEAVY ALONG THIS BOUNDARY WITH STEEP LAPSE RATES UP TO 600 MB AND MODERATE WESTERLY FLOW. 1 TO 2 INCH PER HOUR RATES IN THE SL VALLEY AT THE PEAK AND 2 TO 3 INCHES IN THE MOUNTAINS. RADAR DEPICTING SNOW SHOWERS INCREASING ACROSS THE IDAHO BORDER PAST HOUR...THIS WILL SPILL SOUTHWARD ACROSS NORTHERN UTAH THIS EVENING. COLD POOL ALOFT...500 MB...REMAINS TO THE NORTH IN IDAHO AND IS CREATING A STRONG JET CORE ALONG THE IDAHO BORDER. NAM/GFS AND RUC SAG THIS GRADIENT SOUTHWARD SO WE COOL FROM -24C AT SLC NOW...TO -28C THIS EVENING. AT THE SAME TIME COOLING CONTINUES BELOW WITH -17C AT 700 MB BY LATE EVENING. THUS STEEP LAPSE RATES WILL CONTINUE THIS EVENING WITH THE INVERSION BASE PROGGED TO RISE UP TO 600 MB BEFORE LOWERING AGAIN AFTER MIDNIGHT WHEN THE UPPER JET STREAK BEGINS TO EXIT AND THE THERMAL GRADIENT AT 500 MB LEVEL SLOWLY RETREATS NORTHWARD. THE WAVE ALONG THIS GRADIENT SHOULD REDEVELOP SNOW EARLY THIS EVENING...ESPECIALLY ALONG THE TERRAIN WHERE NORTHWEST FLOW UPSLOPE FORCING WILL PERSIST FROM THE WASATCH PLATEAU NEAR MT PLEASANT NORTHWARD TO THE BEAR RIVER RANGE. THERE IS ALSO A WINDOW FOR LAKE ENHANCEMENT OR EVEN A BAND THIS EVENING WITHIN UNIFORM NORTHWEST FLOW AND LOWER LEVEL MOISTURE AS THE VERY COLD AIR MASS FILTERS ACROSS THE GSL. COLD AIR SETTLES ACROSS UTAH WITH -18C ISOTHERM LINGERING INTO MONDAY AFTERNOON ACROSS THE NORTH. THIS SETS THE STAGE FOR A VERY COLD DAY FOLLOWED BY BITTER COLD NIGHT AND MOSTLY CLEAR SKIES. NAM AND GFS DISPLAY A 1052 MB SURFACE HIGH SETTLING OVER WYOMING. THIS SHOULD BE OUR COLDEST PERIOD SO FAR THIS YEAR FOR MANY PLACES AND EVEN BELOW ZERO POSSIBLE FOR SLC AT NIGHT. STRONG UPPER RIDGE RIDES OVER THE COLD DOME AND WARM 700 MB AIR TO 0C BY TUESDAY AFTERNOON IN LIGHT SOUTHWEST FLOW...LEADING TO STRONG INVERSION OVER SNOW COVERED VALLEYS. THIS UPPER RIDGE IS SHORT LIVED AND MODELS CONTINUE TO PROG INCREASING SOUTHWEST FLOW WEDNESDAY INTO THURSDAY. 55 KNOTS OF MOIST ADVECTION AT 700 MB FORECAST BY THURSDAY AFTERNOON ACROSS THE WRN PTN OF UT. STRONG SOUTHERLY MILD FLOW AND TRAPPED COLD AIR WILL CREATE NORTHERN VALLEY PTYPE ISSUES BUT LIKELY ALL SNOW FOR NORTHEAST VALLEYS LIKE UINTA BASIN. SHOULD BE ABLE TO MIX OUT THE WESTERN VALLEYS BY THURSDAY AFTERNOON GIVEN PROGGED FLOW AND PRESSURE GRADIENT. LARGE EPAC TROF SENDS A WAVE ACROSS THE GREAT BASIN THURSDAY NGT INTO FRIDAY...AND THEN ANOTHER WAVE AND COLD FRONT SATURDAY AFTN INTO SUNDAY. ECMWF STRONGER WITH THE SECOND WAVE THAN THE GFS. GFS ENSEMBLE SPREAD IS SMALL FOR NEXT WEEKEND WITH SPREAD DEVELOPING NOT UNTIL THE FINAL WAVE. THIS DEEP UPPER TROUGH ADVERTISED TO DIG ACROSS THE WEST COAST AND SEND A STRONG COLD FRONT THRU UT BY LATE SUNDAY AND INTO MON. A STATEWIDE EVENT DUE TO THE INITIALLY WAVE TAKING A DIRECT HIT AND THE FINAL SYSTEM DIGGING FAR SOUTH. RATHER HIGH CHANCES IN THE GRIDS WITH LIKELY VALUES IN THE MOUNTAINS. PUBLIC INFORMATION STATEMENT HAS LATEST SNOWFALL TOTALS. && .AVIATION...SNOW SHOWERS ARE EXPECTED TO OCCUR IN THE VICINITY OF SLC TERMINAL BETWEEN 03Z AND 07Z THIS EVENING WITH A 30 PERCENT CHANCE OF SNOW DIRECTLY IMPACTING THE TERMINAL WITH MVFR OR IFR CONDITIONS. THERE IS A 30 PERCENT CHANCE THAT WINDS COULD SHIFT TO THE SOUTHEAST AS EARLY AS 04Z DUE TO HEAVIER SNOW SHOWERS BANKED UP AGAINST THE MOUNTAINS EAST OF SLC. && .SLC WATCHES/WARNINGS/ADVISORIES... UT...WINTER STORM WARNING NRN WASATCH MTS UNTIL 11 PM...UTZ007. ...HEAVY SNOW WARNING WASATCH MT VLYS UNTIL 9 PM...UTZ006. ...SNOW AND BLOWING SNOW ADVISORY FOR THE SRN WASATCH WRN UINTA AND CENTRAL MTS UNTIL 11 PM...UTZ008-009-517. ...SNOW ADVISORY FOR NRN WASATCH FRONT UNTIL 11 PM UTZ002. ...SNOW ADVISORY FOR CENTRAL AND SRN WASATCH FRONT UNTIL 11 PM... UTZ003-004. WY...NONE. && $$ TARDY AVIATION...SCHOENING FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT... HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE) ut AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 845 PM CST SAT DEC 29 2007 .UPDATE...11-3.9 MICRON SATELLITE IMAGERY INDICATED BACK EDGE OF STRATUS OVER IOWA AND NORTHWEST IL WAS MOVING NORTHEASTWARD THIS EVENING. LATEST 11-3.9 MICRON SATELLITE IMAGERY...ALONG WITH SURFACE OBSERVATIONS...INDICATED FOG AND STRATUS WAS FILLING BACK IN OVER NORTHEAST IOWA WHERE AIR HAD COOLED QUICKLY AND SATURATED. IN ADDITION...PROFILERS AT BLUE RIVER WI AND SLATER IOWA INDICATED 15-25KT 925MB SOUTHWESTERLY FLOW...WHICH WOULD SUPPORT STRATUS REDEVELOPING PER UPS FOG STUDY. LATEST RUC AND 00Z 30DEC07 NAM/WRF INDICATED MOISTURE-LADEN BOUNDARY LAYER SHOULD REMAIN IN PLACE ACROSS THE FORECAST AREA TONIGHT. THUS...EVEN IF STRATUS CLEARS OVER PARTS OF THE AREA...ADDITIONAL FOG AND/OR STRATUS SHOULD DEVELOP BACK IN...AS EVIDENCED BY CURRENT CONDITIONS ACROSS NORTHEAST IOWA. THEREFORE...PLAN TO CONTINUE WITH SPIRIT OF CURRENT FORECAST...WHICH SUGGESTS CONSIDERABLE CLOUD COVER SHOULD REMAIN DURING THE NIGHT. ONLY ADDITION TO DATA BASE WAS TO ADD AREAS OF DENSE FOG ACROSS PARTS OF NORTHEAST IOWA AND SOUTHWEST WI. PLAN TO UPDATE ZONES BY 0330Z THIS EVENING...PRIMARILY TO INCORPORATE AFOREMENTIONED ADDITION OF DENSE FOG. && THOMPSON .PREV DISCUSSION... /ISSUED 252 PM CST SAT DEC 29 2007/ SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT FORECAST CONCERNS THIS PACKAGE...CLOUDS/TEMPERATURES AND SMALL PRECIPITATION CHANCES TROUGH THE PERIOD. 18Z SURFACE ANALYSIS SHOWED HIGH PRESSURE CENTERED OVER THE MID/ LOWER MS VALLEY AND LOW PRESSURE CENTERED OVER MT. VIS/FOG-PRODUCT IMAGERY AND SFC OBS INDICATED A BROAD AREA OF LOW CLOUDS/STRATUS ACROSS MUCH OF MN/WI/IA. WITH A WEAK SOUTH/SOUTHWEST FLOW BETWEEN THE HIGH/LOW...SOME CLEARING WAS PUSHING SLOWLY NORTH ACROSS THE SOUTHWEST HALF OF IA. VIS IMAGERY ALSO SHOWED THE SNOW COVER EXTENDED SOUTH INTO NORTHERN MO TO THE TX PANHANDLE AND WEST TO THE FRONT RANGE OF CO/WY. THE WEAK SOUTHERLY FLOW AND SOME WEAK 850MB WARM ADVECTION IN AND JUST ABOVE THE MOIST LOW LEVEL WERE PRODUCING A BROAD BAND OF -SN/FLURRIES ACROSS CENTRAL MN INTO CENTRAL WI. 29/12Z NAM/GFS LOOK TO HAVE INITIALIZED QUITE WELL AND PRESENT RATHER SIMILAR SOLUTIONS FOR TONIGHT INTO TUE NIGHT. NAM DOES REMAIN STRONGER WITH A SFC LOW ACROSS THE REGION SUN NIGHT/MON. DPROG/DT OF 500MB HGTS AT 29/12Z SHOWED THE NAM/GFS RUNS OF 27/12Z AND 28/12Z VERIFIED QUITE WELL ACROSS NOAM WITH SLIGHT EDGE AND BETTER RUN-TO- RUN CONSISTENCY TO GFS. THRU 36HRS TREND IS A BIT SLOWER WITH THE SHORTWAVE TROUGH INTO THE LOWER OH VALLEY BY 00Z MON. THRU 84HRS TREND LOOKS TO BE A SLIGHTLY STRONGER/SLOWER SOLUTION WITH THE NEXT SHORTWAVE INTO THE MID MS VALLEY ON MON /TREND TOWARD 28/12Z NAM/... AND WITH THE 3RD WAVE ACROSS THE REGION ON TUE /TOWARD 28/12Z GFS/. CHECK OF OBS VS. MODEL DATA AT 18Z SHOWED NAM/GFS REASONABLE WITH THE SFC MASS FIELDS ACROSS CENTRAL NOAM. PER WV IMAGERY...BOTH MODELS LOOKED TO HAVE DECENT DEPICTIONS OF THE SHORTWAVE FEATURES ACROSS NOAM/EASTERN PAC...WITH PERHAPS SLIGHT EDGE TO GFS. WITH GFS SHOWING THE BETTER RUN-TO-RUN CONSISTENCY...A BIT BETTER WITH SHORTWAVE DETAILS AT 18Z AND NAM TRENDING TOWARD ITS SOLUTION /ESPECIALLY WITH THE MONDAY SYSTEM/ FAVORED IT/S SOLUTION. FORECAST CONFIDENCE IN THE SHORT TERM AVERAGE TO GOOD THIS CYCLE. FOR THE SHORT TERM...WEAK 850MB WARM ADVECTION PERSISTS TONIGHT. SOUNDINGS AND X-SECTIONS INDICATE SOME DECREASE OF THE DEPTH OF MOISTURE THRU THE NIGHT...BUT THIS LOOKS OFF-SET BY SOME WEAK 700MB WARM ADVECTION SPREADING INTO THE AREA. TEMP AT THE TOP OF MOIST LAYER REMAINS AROUND -10C. PREVIOUS FORECAST HAD -FZDZ/FLURRY MENTION TONIGHT AND LEFT THIS AS IS. BIGGER QUESTION IS WILL THE CLEARING MAKE IT INTO THE SOUTH END OF THE FORECAST AREA TONIGHT. WITH THE SNOW COVER AND COOLING...ALONG WITH THE DEEPER WARM ADVECTION OVER THE TOP OF THIS LAYER...CLEARING MAY BRIEFLY MAKE IT INTO THE SOUTHWEST END OF THE FORECAST AREA BEFORE MORE CLOUDS REDEVELOP. -SN/-FZDZ THREAT CONTINUES ON SUN WITH SLIGHTLY STRONGER 850-700MB WARM ADVECTION OVER/IN THE TOP OF THE MOIST LAYER. CONFINED -SN CHANCE AND SMALL BUT HIGHER POP ACROSS THE NORTH PART OF THE FORECAST AREA WHERE MOISTURE WILL BE A BIT DEEPER. FOR SUN NIGHT THRU TUE THE SERIES OF SHORTWAVES SLIDE ACROSS OR JUST SOUTHWEST OF THE FORECAST AREA. MODEL SOUNDINGS AND TIME-HGT X- SECTIONS INDICATE AN INCREASED DEPTH OF MOISTURE AS THESE SHORTWAVE PASS. THIS AS THE STRENGTH/DEPTH OF THE CYCLONIC FLOW INCREASES AND THE AIRMASS SLOWLY COOLS. THIS WITH SOME PV ADVECTION AND 700-300MB QG CONVERGENCE WITH THE PASSING SHORTWAVES. GFS WETTER IN THE MID/ UPPER LEVELS WITH THESE FEATURES THAN NAM...AND PRODUCES MORE LIGHT QPF ACROSS THE FORECAST AREA IN THE SUN NIGHT THRU TUE TIME-FRAME. FAVORING THE MORE MOIST GFS FOR THIS TIME...ALONG WITH BROAD BUT GENERALLY WEAK CONVERGENCE/LIFT...-SN POPS IN THE CHANCE RANGE FOR SUN NIGHT/MON LOOK GOOD AND RAISED THEM INTO CHANCE RANGE FOR MON NIGHT/TUE. THESE CHANCES GENERALLY BLEND WELL WITH NEIGHBORING GRIDS. STILL PLENTY OF TIME TO DETAIL ANY PERIODS OF HIGHER -SN CHANCES OR POSSIBLE ACCUMULATING LIGHT SNOW ONCE TIMING OF ANY SHORTWAVE OR STRONGER PERIODS OF LIFT CAN BE DETERMINED. WITH PASSAGE OF THE STRONGER SHORTWAVE TROUGH ON TUE...DEEPER SUBSIDENCE AND MID/UPPER LEVEL DRYING SPREAD SOUTHEAST ACROSS THE AREA TUE NIGHT. WAS OPTIMISTIC FOR SOME DECREASE OF CLOUDS/CLEARING TUE NIGHT BEHIND THE SHORTWAVE. TIGHTER GRADIENT OVER THE AREA TUE INTO TUE NIGHT AS THE SFC LOW HOLDS OVER THE EASTERN GREAT LAKES AND STRONG HIGH PRESSURE BUILDS INTO THE NORTHERN PLAINS BEHIND THE LAST SHORTWAVE. WITH CLOUD EXPECTED TO PERSIST TONIGHT...FAVORED WARMER OF GUIDANCE LOWS. WITH PERSISTENT LOW CLOUDS...LEANED TOWARD COOLER OF GUIDANCE HIGHS SUN/MON AND WARMER OF GUIDANCE LOWS SUN/MON NIGHTS. FAVORED A BLEND OF GFS MEX MOS AND HPC GUIDANCE FOR TUE...THEN TRENDED TOWARD COLDER OF GUIDANCE FOR LOWS TUE NIGHT AS THE ARCTIC AIRMASS SPREADS SOUTH ACROSS THE REGION. LONG TERM...WEDNESDAY THROUGH SATURDAY 29/00Z MEDIUM RANGE MODELS REMAIN IN REASONABLY GOOD AGREEMENT WITH EACH OTHER AND THEIR PREVIOUS RUNS IN THE WED-SAT PERIOD. ECMWF GENERALLY SHOWS THE BETTER RUN-TO-RUN CONSISTENCY. SOME LESSER TIMING DIFFERENCES WITH THE PROGRESSIVENESS OF THE EAST/WEST COAST TROUGHS FOR THU-SAT WITH GFS ENSEMBLE MEAN LOOKING TO BE A GOOD COMPROMISE. FORECAST CONFIDENCE IN THE LONG TERM REMAINS AVERAGE TO GOOD. LONGWAVE RIDGING MOVES INTO CENTRAL NOAM BY WED. COLD CANADIAN SFC HIGH UNDER/EAST OF THE RIDGE AXIS SLIDES ACROSS THE AREA WED/WED NIGHT FOR A SEASONABLY COLD PERIOD. EVEN WITH THE AMPLIFIED LONGWAVE PATTERN OVER NOAM/EASTERN PAC BY MIDWEEK...IT REMAINS PROGRESSIVE AS STRONG ENERGY IN THE EASTERN PAC/GULF OF AK PUSHES EAST. THE SFC HIGH RETREATS LATER WED NIGHT/THU WITH STRONG 850-700MB WARM ADVECTION SPREADING ACROSS THE AREA. MUCH OF THIS GOES INTO WARMING AND HGTS/RIDGING ALOFT BUILDING ACROSS THE REGION. STRONG INVERSION DEVELOPS OVER THE AREA IN THE 925-850MB LAYER FOR THU INTO FRI...DUE TO EXPANSIVE SNOW FIELD ACROSS THE REGION. INVERSION AND THE SNOW COVER WILL TEMPER THE WARMUP IN THE LOW LEVEL WARM ADVECTION FLOW FOR THU INTO SAT. BIGGEST QUESTION IS POTENTIAL FOR LOW CLOUD/ STRATUS DEVELOPMENT AS THE SOUTH/SOUTHWEST EDGES OF THE SNOW COVER START TO MELT AND THIS MOISTURE IS ADVECTED NORTH UNDER THE INVERSION. THIS ESPECIALLY SO BY THU NIGHT AND BEYOND. LEFT SKY GRIDS IN THE PARTLY CLOUDY RANGE FOR THU NIGHT THRU FRI NIGHT FOR NOW. MODELS RATHER CONSISTENT IN EJECTING A STRONGER PIECE OF ENERGY OUT OF THE WEST COAST TROUGH AND INTO THE UPPER MIDWEST SAT. SMALL -RA/-SN CHANCE ON SAT REASONABLE FOR NOW WITH A SHORTWAVE TROUGH MOVING THRU AND SOME WARM AIR ALOFT OVER THE AREA. LEANED TOWARD COOLER OF GUIDANCE MAXES/MINS FOR WED THRU THU...THEN COOLER OF GUIDANCE HIGHS FOR FRI/SAT WITH THE SNOW COVER AND POTENTIAL FOR LOW CLOUDS. POTENTIAL FOR LOW CLOUDS AND SOME SOUTH WINDS THU/FRI NIGHTS LEADS TO FAVORING WARMER OF GUIDANCE LOWS THESE PERIODS. AVIATION...TONIGHT AND SUNDAY PERSISTENCE LOOKS LIKE BEST BET RIGHT NOW WITH WEAK SURFACE RIDGE PASSING THROUGH THE AREA AND MVFR CONDITIONS REMAIN FAIRLY STABLE. WEAK WARM AIR ADVECTION SPAWNED SOME LIGHT SNOW EARLIER BUT BULK OF THAT ACTIVITY WILL CONTINUE TO SHIFT NORTHEAST TONIGHT. AS SOUTH TO SOUTHWEST FLOW CONTINUES TONIGHT WITH RIDGE PASSAGE...EXPECT MVFR CONDITIONS TO GRADUALLY SLIP TO IFR WITH LOWERING CEILINGS AND VISIBILITIES AGAIN AS THE NIGHT GOES ON. COULD SEE SOME IMPROVEMENT TOMORROW BUT APPROACH OF SHORT WAVE TROUGH MAY HELP GENERATE ENOUGH LIFT FOR SPORADIC LIGHT SNOW OR FREEZING DRIZZLE AS WELL. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM...RRS AVIATION..........SHEA wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE UPTON NY 455 AM EST MON DEC 31 2007 .SYNOPSIS... A LOW PRESSURE SYSTEM SOUTHEAST OF LONG ISLAND WILL RAPIDLY MOVE NE OFF THE NEW ENGLAND COAST AS IT INTENSIFIES TODAY. A WEAK HIGH PRES SYSTEM WILL ADVECT E AND PASS OFF THE COAST THIS EVENING. A LOW PRES SYSTEM OVER THE OH VALLEY WILL INTENSIFY AS IT MOVES ENE TOWARD THE REGION NEW YEAR`S DAY. A SECONDARY LOW IS FORECAST TO DEVELOP OFF THE NEW ENGLAND COAST AND TRACK NE AS A SURGE OF ARCTIC AIR MOVES SSE ACROSS THE REGION WED INTO THU. THE ARCTIC HIGH WILL SLOWLY MODIFY AS IT MOVES SLOWLY S OFF THE MID ATLANTIC COAST THROUGH SAT. && .NEAR TERM /UNTIL 9 AM THIS MORNING/... A WINTER WEATHER ADVISORY REMAINS IN EFFECT UNTIL 9 AM FOR NYC`S EXTREME NW AND N SUBURBS...FOR A LIGHT WINTRY MIX OF WET SNOW...SLEET AND FREEZING RAIN. BASED ON THE NE ADVECTION OF STRONG UPPER AND MID LVL SUBSIDENCE ACROSS THE REGION...THE SW FRINGE OF THIS LOW/S ASSOCIATED PRECIPITATION SHIELD HAS DRYED. BECAUSE THE UPPER LVL WAVE IS OPEN AND PROGRESSIVE...I/M NOT EXPECTING ANY PRECIP TO WRAP AROUND THIS DEVELOPING LOW AND MAKE IT FAR ENOUGH S TO AFFECT OUR REGION. WE MAY DECIDE TO CANCEL THE WINTER WEATHER ADVISORY EARLIER THAN 9 AM BASED ON CURRENT OBSERVATIONS AND FCST TRENDS. && .SHORT TERM /9 AM THIS MORNING THROUGH WEDNESDAY/... FOR TODAY...NEW YEAR/S EVE...A MILD AND DRY...BUT GUSTY DAY IS ON TAP FOR THE REGION AS A STRONG W WIND FLOW INCREASES DOWN SLOPE ACROSS THE AREA...CAUSING TEMPS TO RISE TO NEAR 50 DEGS ACROSS PARTS OF NYC...MILDER THAN OUR PREV FORECASTS. FOR NEW YEAR/S DAY...IT LOOKS LIKE A WET ONE ACROSS MOST OF THE REGION...WITH THE GREATEST POTENTIAL FOR A WINTER WEATHER ADVISORY ACROSS ORANGE COUNTY NY. AS AN INTENSIFYING LOW MOVES ENE FROM THE OHIO VALLEY...A BRISK SE WIND FLOW WILL DEVELOP AND QUICKLY WARM THE SURFACE AND BOUNDARY LAYER ALONG THE COAST. THE UPPER LVL DYNAMICS ASSOCIATED WITH THIS SYSTEM ARE FAIRLY STRONG AND UP TO 1/2 INCH OF RAIN IS QUITE POSSIBLE BEFORE A SECONDARY DEVELOPS LATE IN THE GAME. IT APPEARS THAT PRECIP WILL DEVELOP AS A WINTRY MIX OF WET SNOW...SLEET AND FREEZING RAIN ACROSS ORANGE COUNTY THAT COULD MEET ADVISORY CRITERIA BASED ON THE INTENSITY OF THE UPSTREAM LOW. STAY TUNED. FOR WEDNESDAY...PREPARE FOR AN ARCTIC SURGE. THERE SHOULD BE JUST ENOUGH LOW LVL MOISTURE POOLING AHEAD OF THE FRONT TO CAUSE SCT SNOW SHOWERS...SOME MODERATE BASED ON INSTABILITY PROFILES. IN FACT...AS AN UPPER LVL LOW AND TROUGH APPROACHES THE REGION...THIS COMBO MAKES SNOW SHOWERS LIKELY ACROSS THE REGION. ALTHOUGH A 30 PCT POP WAS INTRODUCED FOR WED...I REALLY THINK A 60 OR 70 PCT POP FOR SNOW SHOWERS IS MORE REALISTIC WHERE MOST AREAS WILL PICK UP ANYWHERE FROM A DUSTING TO 1 INCH. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... WIND CHILLS BECOME A PROBLEM FOR WED NIGHT...WITH VALUES APPROACHING 10 TO 15 DEGS BELOW ZERO. STAY TUNED FOR A POTENTIAL WIND CHILL ADVISORY. OTHERWISE...THE ARCTIC AIR MASS WILL GRADUALLY MODIFY THROUGH FRIDAY. THE RETURN FLOW AROUND THE HIGH...WILL BRING WELL ABOVE NORMAL TEMPS ACROSS THE REGION BY THE END OF THE WEEKEND AS A 580-590 500 MB HIGH DEVELOPS OFF THE SE US COAST. E MAY B DRESSING IN SHORTS BY EARLY NEXT WEEK AS THE WEATHER ROLL A COASTER CONTS. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... GENERALLY IFR CONDITIONS PREVAIL ACROSS THE AREA. RUC SEEMS TO HAVE THE BEST HANDLE ON THE SITUATION...ALTHOUGH STILL A LITTLE 1 TO 2 DEGREES TOO COLD SIDE IN THE LOW LEVELS AS COMPARED TO 05Z ACARS SOUNDING AT KLGA. ALSO NOTING THE MID AND UPPER LEVEL DRYING ON WV IMAGERY INTRUDING INTO DELAWARE WHICH WILL BRING AN END TO THE DEEP MOISTURE AND CHANGE RAIN TO DRIZZLE. THINK THIS WILL OCCUR IN THE NEXT 3 TO 4 HOURS...POSSIBLY A FEW HOURS LATER AT KGON. WATCHING SFC TEMPS ACROSS INTERIOR LOCATIONS...KSWF HAS BEEN RIGHT AT THE FREEZING MARK THE LAST FEW HOURS AND IT SHOULD HOLD HERE FOR THE REMAINDER OF THE NIGHT WHICH WOULD KEEP -FZRA THE DOMINANT P-TYPE BEFORE CHANGING TO -FZDZ. HOWEVER...COULD SEE SOME SNOW MIX IN AS THE COLUMN COOLS BETWEEN NOW AND 09Z. SAME GOES FOR KHPN. ALL OTHER TERMINALS SHOULD REMAIN PLAIN RAIN/DRIZZLE. THAT SAID...EXPECT IFR CONDITIONS TO PREVAIL UNTIL AROUND 12Z. COULD SEE SOME IMPROVEMENT BACK TO MVFR BETWEEN 10 AND 12Z. ALL PRECIP SHOULD COME TO AN END BY 12/13Z WITH CONDITIONS IMPROVING BACK TO VFR AND ONLY GUSTY W/NW LEFT TO CONTEND WITH. E/NE WINDS WILL GRADUALLY BACK TO THE N THEN NW AS THE COASTAL LOW PASSES TO THE SOUTH AND EAST LATE TONIGHT/EARLY MON MORNING. SUSTAINED WINDS SHOULD RANGE BETWEEN 12 AND 17 KT WITH GUSTS BETWEEN 25 AND 30 KT AFTER 15Z. GUSTS SHOULD SUBSIDE EARLY IN THE EVENING AND BECOME LIGHT AND VARIABLE AFTER 00Z. OUTLOOK FOR 06Z TUESDAY THROUGH THURSDAY...VFR REMAINS THROUGH MONDAY NIGHT. SUB-VFR CONDITIONS ARE AGAIN LIKELY TUESDAY AND TUESDAY EVENING AS AN ALBERTA CLIPPER LOW AND COLD FRONT PASS ACROSS THE AREA. RAIN NEAR THE COAST...RAIN/SNOW INTERIOR. THIS WILL BE FOLLOWED BY GUSTY W-NW FLOW LATER TUE NIGHT THROUGH THU AS THE OFFSHORE LOW INTENSIFIES AND DRAWS DOWN ARCTIC AIR. LIGHT SNOW SHOWERS OR FLURRIES WILL BE POSSIBLE ON WEDNESDAY...OTHERWISE DRY. && .MARINE... TODAY THROUGH WEDNESDAY... WINDS HAVE INCREASED AS THE LOW HAS NEARED THE WATERS. EXPECT THE WINDS TO DIMINISH SOMEWHAT THROUGH THE MID MORNING HOURS AS LOW PRESSURE AND LOW LEVEL JET PASSES TO THE EAST. SMALL CRAFT ADVISORY REMAINS UP FOR THE OCEAN WATERS...AND WILL KEEP OTHER HEADLINES AS THEY ARE EVEN THOUGH WINDS ARE CURRENTLY QUITE CLOSE TO CRITERIA. AGAIN...WINDS WILL DIMINISH...THEN INCREASE IN WESTERLY FLOW BEHIND DEPARTING LOW LATER THIS MORNING. WINDS DIMINISH LATE THIS AFTERNOON AND THIS EVENING AS HIGH PRESSURE BUILDS. THEN NEXT AREA OF LOW PRESSURE PASSES JUST TO THE NORTH OF THE WATERS TUESDAY...AND DRAGS A COLD FRONT THROUGH. STRONG WEST FLOW BEHIND THIS LOW/FRONT TUESDAY NIGHT. ARCTIC FRONT PIVOTS AROUND STRONG LOW PRESSURE WEDNESDAY...AND STRONG WEST WINDS TURN TO THE NORTHWEST AND REMAIN EQUALLY STRONG. WEDNESDAY NIGHT THROUGH FRIDAY NIGHT... WITH TIGHT PRESSURE GRADIENT AND LOW LEVEL CAA/INSTABILITY BEHIND THIS FRONT...EXPECT STRONG NORTHWEST WINDS TO PREVAIL INTO THURSDAY. GALES QUITE POSSIBLE. HIGH PRESSURE BUILDS AND CONDITIONS IMPROVE THU NIGHT AND FRI. HIGH PRES PASSES TO THE SOUTH FRI NIGHT...AND WINDS INCREASE ONCE AGAIN. && .HYDROLOGY... THE NEXT SYSTEM COULD PRODUCE UP TO 1/2 INCH OF RAIN DURING NEW YEAR/S DAY. && .EQUIPMENT... KOKX WSR-88D IS FULLY OPERATIONAL...THOUGH A SOFTWARE/HARDWARE ISSUE WITH OUR AWIPS HAS CAUSED INTERRUPTIONS OF EXTERNAL DISSEMINATION. PLEASE CONTACT US IF YOU NOTICE THAT KOKX RADAR IS NOT AVAILABLE. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR CTZ005- 006. NY...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR NYZ067- 068. NJ...WINTER WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR NJZ002. MARINE...SMALL CRAFT ADVISORY FROM 11 AM THIS MORNING TO 6 PM EST THIS AFTERNOON FOR ANZ330-335-338-340-345. SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ353- 355. SMALL CRAFT ADVISORY UNTIL 9 PM EST THIS EVENING FOR ANZ350. && $$ SYNOPSIS...GC NEAR TERM...GC SHORT TERM...GC LONG TERM...BG AVIATION...PW MARINE...PW HYDROLOGY...GC EQUIPMENT... ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 305 AM CST MON DEC 31 2007 .DISCUSSION... DAYS 1-2... A PACIFIC FRONT PUSHED THROUGH WESTERN KANSAS DURING THE OVERNIGHT, FORCED BY A DYNAMICALLY GENERATED SURFACE ANTICYCLONE OVER THE GREAT BASIN. THE INITIAL FRONTAL SURGE BROUGHT WINDS GUSTING ABOVE 40 MPH IN PLACES. THE STEADY NORTHWEST WIND IS HELPING TO KEEP THINGS MIXED IN THE BOUNDARY LAYER THIS MORNING. AT 08Z, 850MB TEMPS AT DDC WERE ABOUT 1C AND THIS IS LIKELY THE REASON TEMPS HAVE RISEN BACK INTO THE LOW 30S. HOWEVER, COLD ADVECTION AT 850MB IS UNDERWAY AND THESE TEMPS WILL CONTINUE TO FALL BEFORE MORNING. A BAND OF MID LEVEL MOISTURE AND LIFT IS ALSO SLICING SOUTHEAST ACROSS MY CWA THIS MORNING ALONG THE SURGING 700MB COLD FRONT. ALTHOUGH A FEW FLURRIES ARE POSSIBLE AS THE BAND OF MID CLOUD PUSHES SOUTH THIS MORNING, WEAK ECHOES ON RADAR AND DRY AIR BELOW 700MB SHOULD KEEP THIS TO A MINIMUM. THE UPPER FLOW PATTERN THROUGH TUESDAY NIGHT WILL DISPLAY A STRONG GSDM (GLOBAL SYNOPTIC DYNAMIC MODEL) LEGACY STAGE 2 LOOK, WITH A DEEP TROUGH IN PLACE OVER THE CENTRAL STATES/GREAT LAKES REGIONS. A PIECE OF THE HUDSON BAY VORTEX CURRENTLY OVER MANITOBA WILL DROP SOUTH SOUTHEAST INTO THIS LONGWAVE TROUGH OVER THE MIDWEST, BRINGING A SLUG OF ARCTIC AIR SOUTH THROUGH THE PLAINS BY TUESDAY. AS IS ALMOST ALWAYS THE CASE, WITH NORTHWEST FLOW ALOFT IN PLACE CHANCES OF PRECIP WILL BE NON-EXISTENT THROUGHOUT THE FORECAST PERIOD. TODAY-- THERE APPEARS TO BE SOME MODEL DIFFERENCES TODAY REGARDING HOW STRONG THE WINDS WILL BE. THE GFS/NAM SUGGEST LIMITED VERTICAL MIXING AND WINDS ONLY ABOUT 30-35KTS AT THE TOP OF THE MIXED LAYER THIS AFTERNOON. THE EARLIER RUNS OF THE RUC13/20 SHOWED WINDS TO ADVISORY CRITERIA THIS AFTERNOON OVER WESTERN KS. THE LATEST RUN, HOWEVER, HAS COME DOWN ON THE WINDS AND THIS MAKES CONFIDENCE IN NOT GOING WITH AN ADVISORY HIGHER. WILL GO SEVERAL KNOTS ABOVE THE NAM12 GUIDANCE WITH GUSTS TO AROUND 30KTS IN THE GRIDS BUT WILL NOT ISSUE ANY HEADLINES. FOR TEMPS, I USED A BLEND OF MODEL SOUNDINGS FROM THE NAM/GFS/SREF AND MIXED DOWN THE AVERAGE LOW LEVEL TEMP DOWN DRY ADIABATIC TO THE SFC. THE NAM12 IS STILL STRUGGLING TO MIX THINGS OUT BELOW 900MB, PROBABLY DUE TO THE SNOW COVER IN THE MODEL AND AS A RESULT THE 2M TEMPS IN THE MODEL LOOK A TAD TOO COLD. WITH DEEPLY MIXED NORTHWEST FLOW IN PLACE SNOW COVER DOES NOT HAVE AS MUCH EFFECT ON THE TEMPS AS IT WOULD OTHERWISE. EVEN WITH SNOW COVER OR ARCTIC AIR IN PLACE, MIXING OUT THE LOWEST 25MB OR SO IS ALMOST A GIVEN ESPECIALLY WITH SOME SUNSHINE. HIGHS SHOULD REACH THE LOW 30S WITH A CHILLY PACIFIC AIRMASS IN PLACE OVER WESTERN KANSAS. TONIGHT-- WITH A STEADY WEST NORTHWEST WIND AT 10KTS OR GREATER EXPECTED ALL NIGHT, LOWS SHOULD STAY UP IN THE TEENS OVER MUCH OF THE FORECAST AREA. TUESDAY-- AN ARCTIC COLD FRONT CURRENTLY NEAR THE CANADIAN BORDER WILL OOZE SOUTH AND EAST INTO THE PLAINS AND WILL "BACK DOOR" FROM THE NORTHEAST INTO MY FORECAST AREA DURING THE DAY. THE 00Z SUITE OF NUMERICAL MODEL GUIDANCE IS FARTHER WEST WITH THIS ARCTIC SURGE THAN 24 HOURS AGO AND I HAVE THUS ADJUSTED MAXES DOWN SEVERAL DEGREES FROM THE PREVIOUS FCST. EVEN WITH DECENT MIXING IN THE LOW LEVELS AND INSOLATION, MAXES WILL LIKELY NOT GET OUT OF THE 20S IN MOST PLACES. TUESDAY NIGHT-- SURFACE WINDS VEER TO WESTERLY AND THEN SOUTHWESTERLY AND BECOME LIGHT WITH THE SURFACE RIDGE SLIDING EAST ACROSS THE FORECAST AREA. WHILE THE POSITION OF THE SFC RIDGE MAY NOT BE TIMED RIGHT WITH THE COOLEST PART OF THE DAY, LOWS SHOULD STILL DROP INTO THE SINGLE DIGITS UNDER CLEAR SKIES. AFTER ALL, IF THE PREVIOUS DAYS` HIGHS ARE ONLY IN THE 20S, IT DOESN`T TAKE MUCH FOR IT TO DROP INTO THE SINGLE DIGITS DURING THE LONG NIGHTS THIS TIME OF YEAR. LACY DAYS 3-7... VERY FEW ADJUSTMENTS WERE MADE TO THE EXISTING DAYS 3-7 FORECAST. ON WEDNESDAY...LOWERED MAX T`S A TAD AS THE INFLUENCE OF THE TUESDAY COLD FRONT WILL LIKELY LINGER A BIT LONGER THAN PREVIOUSLY THOUGHT. THERE IS STILL SOME LIGHT SNOW COVER ON THE GROUND...AND THIS WILL SUPPRESS SURFACE HEATING A LITTLE. ALSO...LOWERED DEW POINTS WEDNESDAY MORNING AND ALSO FRIDAY MORNING. ALSO...EXPECT CIRRUS AND PERHAPS A FEW MID LEVEL ALTOCUMULUS CLOUDS TO INCREASE WEDNESDAY... WHICH WILL THWART FULL SOLAR HEATING. DID NOT CHANGE MUCH ELSE THROUGHOUT THE EXTENDED. DO NOT SEE MUCH CHANCE FOR ANY PRECIPITATION. WEST TO NORTHWEST FLOW WILL BE ESTABLISHED FOR MUCH OF THE THU-SAT PERIOD...SETTING UP A DOWNSLOPE CONDITION WHICH SHOULD BRING A GRADUAL WARM UP. HOW MUCH SNOW COVER WILL STILL EXIST COULD AFFECT THE RESULTING MAX TEMPS...BUT THINK PLENTY OF SUN AND DOWNSLOPE WINDS WILL LEAD TO A MAJOR MELT OFF PRIOR TO FRIDAY. FOR NOW...WENT A FEW DEGREES WARMER ON SAT THAN ON FRI...THINKING THE WARM AIR WILL SLOWLY ERODE THE COLD BOUNDARY LAYER FROM SOUTHWEST TO NORTHEAST AND BE STRONGER ON SATURDAY. WILL BACK TEMPERATURES DOWN A SHADE ON SUNDAY AS THE NORTHWEST DOWNSLOPE AFFECT WILL BE LESSENED AS A SHORT WAVE APPROACHES FROM THE WEST. 12 .AVIATION... VFR CIGS AND VSBYS IN STORE THROUGH 01/06Z. SURFACE AND LOW LEVEL WINDS WILL BE WINDY OUT OF THE NORTHWEST AS A MID-LEVEL WAVE PASSES EASTWARD TO THE NORTH OF OUR TAF AREA. EXPECT GUSTY NORTHWEST WINDS IN THE 25-35KT RANGE AFTER 18Z. && .PRELIMINARY POINT TEMPS/POPS... DDC 33 12 27 5 / 0 0 0 0 GCK 33 11 28 5 / 0 0 0 0 EHA 33 14 31 10 / 0 0 0 0 LBL 34 12 29 7 / 0 0 0 0 HYS 32 12 25 3 / 0 0 0 0 P28 35 16 26 11 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN27/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MST MON DEC 31 2007 .DISCUSSION...FORECAST CONCERNS ARE WINDS AND TEMPERATURES TODAY FOLLOWED BY TEMPERATURES THROUGH THE REMAINDER OF THE SHORT TERM PERIOD. MAY SEE BORDERLINE WIND CHILL ADVISORY CRITERIA THRESHOLDS BEING MET ACROSS FAR EASTERN COLORADO TONIGHT. .SHORT TERM (TODAY-WEDNESDAY NIGHT)... TODAY/TONIGHT...WINDS WILL INCREASE THROUGHOUT THE DAY AS UPPER JET IN BETWEEN UPPER TROUGH SLOWLY MOVING TO OUR EAST AND APPROACHING UPPER RIDGE TO OUR WEST DEVELOPS. QUESTION BECOMES JUST HOW STRONG THE WINDS WILL BE...COMPLICATED BY SNOW PACK OVER MUCH OF THE AREA...DEEPEST ACROSS FAR EASTERN COLORADO AND SOUTHWEST NEBRASKA. BASED ON A COMPILATION OF MOS GUIDANCE AND RUC13/RUC WINDS HAVE PAINTED GENERALLY WINDY CONDITIONS ACROSS THE AREA. INTERESTING THAT THE RUC13 PICKS UP ON HIGHER SUSTAINED WINDS EAST OF THE DEEPER SNOW PACK. TEMPERATURES WILL BE JUST AS TRICKY TODAY AS 850 TEMPERATURES DROP ABOUT 10-15F FROM SUNDAYS READINGS. THIS ALONE (PLUS THE PAST FEW DAYS PERFORMANCE) WOULD SUPPORT NEAR 20 ACROSS FLAGLER COLORADO TO THE MID 20S TO NEAR 30 EAST OF THE CO/KS BORDER...WARMEST ACROSS THE EAST...SIMILAR TO THE NAM/GFS/SREF 2M TEMPS. MOS GUIDANCE WILL BE THROWN OUT AS IT HAS NO CLUE AS TO SNOW PACK OR AIRMASS IN THE AREA. FOR TONIGHT NORTHWEST WINDS WILL REMAIN IN THE 15-25 MPH RANGE PREVENTING A COMPLETE DROP IN MIN TEMPS. HOWEVER...WITH 850 TEMPERATURES STILL DROPPING OVERNIGHT TEMPERATURES WILL CONTINUE A STEADY FALL. HAVE GONE WITH READINGS IN THE SINGLE DIGITS ABOVE ZERO ACROSS THE WEST WITH 10-15 EAST OF THE CO/KS BORDER. THE COMBINATION OF THE WIND AND TEMPS WILL PRODUCE WIND CHILL READINGS IN THE -10 TO -15F RANGE ACROSS FAR EASTERN COLORADO...CLOSE TO WIND CHILL ADVISORY CRITERIA. WILL ADDRESS THIS IN THE MORNING HWOGLD PRODUCT. TUESDAY/TUESDAY NIGHT...850 TEMPERATURES CONTINUE TO FALL SOME 5-8F AS A DISTURBANCE MOVES INTO THE BASE OF THE UPPER TROUGH OVER THE OHIO VALLEY....SLOWING THE WARMING THAT WAS PREVIOUSLY EXPECTED. AM GONNA STICK CLOSE TO THE 850/2M COMBINATION FROM THE GFS/NAM/NGM/UKMET/SREF WHICH WOULD SUPPORT AFTERNOON TEMPERATURES ONLY IN THE 20S WITH PERHAPS SOME TEENS IN EASTERN COLORADO. WILL HAVE ANOTHER BLUSTERY/WINDY DAY AGAIN AS THE STRONGER WINDS UNDERNEATH THE UPPER JET MIX DOWN DURING THE AFTERNOON HOURS. BY 22-23Z WINDS WILL QUICKLY DECREASE TO UNDER 10 MPH. SOME CIRRUS MAY MOVE INTO THE SOUTHWEST 1/2 OR 1/3 OF THE AREA LATE TUESDAY NIGHT AS THE UPPER RIDGE AXIS CONTINUES ITS APPROACH TOWARD THE AREA. WINDS WILL GRADUALLY BACK TO THE SOUTHWEST WITH PRETTY LIGHT SPEEDS. THE COMBINATION OF LIGHT WINDS AND A GENERALLY CLEAR SKY WILL PROMOTE GOOD RADIATIONAL COOLING FOR A GOOD PORTION OF THE NIGHT BEFORE WARMER AIR ALOFT MOVES IN WITH THE UPPER RIDGE AXIS. MAY SEE TEMPERATURES START TO INCREASE IN THE WEST AFTER MIDNIGHT. WILL GO FOR READINGS GENERALLY NEAR OR SLIGHTLY BELOW ZERO IN FAR EASTERN COLORADO TO THE SINGLE DIGITS ABOVE ZERO ACROSS THE REMAINDER OF THE AREA. WEDNESDAY/WEDNESDAY NIGHT...HAVE FOLLOWED THE COOLER UKMET/ECMWF/GFS AT 850 AS THEY CAPTURE THE LOW LEVEL THERMAL FIELDS BETTER WITH SNOW PACK STILL EXPECTED TO BE AROUND. THE NAM IS AT LEAST 15F WARMER THAN THE OTHER GUIDANCE PIECES AND HAS BEEN DISREGARDED. WITH THAT SAID...STILL PLANNING ON WARMING TEMPERATURES INTO THE 30S...QUITE A BIT COLDER THEN PREVIOUSLY EXPECTED. CIRRUS MAY BECOME RATHER THICK DURING THE TIME OF PEAK HEATING AS THE RIDGE AXIS MOVES ON TOP OF THE AREA. MIN TEMPS WILL BE NOTICEABLY LESS COLD WHEN COMPARED TO TUESDAY NIGHT AS THE AIRMASS CONTINUES TO MODIFY/WARM WITH CIRRUS AND LIGHT SOUTH/SOUTHWEST WINDS CONTINUE. GENERALLY WENT WITH AROUND 10 IN EASTERN COLORADO TO MID TEENS ELSEWHERE. .LONG TERM (THURSDAY-SUNDAY)... NO SIGNIFICANT CHANGES PLANNED AT THIS TIME. 850 TEMPERATURES WILL CONTINUE TO WARM BUT MODEL AGREEMENT ON HOW FAST OR SLOW THIS HAPPENS IS AT QUESTION. ADDITIONALLY...SNOW PACK WILL STILL BE A FACTOR FOR AT LEAST THE EARLY PORTION OF THE LONG TERM AND ITS UNLIKELY THE MODELS WILL BE HANDLING IT WELL. MOS GUIDANCE IS PRETTY MUCH WORTHLESS RIGHT NOW AS IT HAS NO CLUE TO THE SMALLER SCALE SNOW FIELDS AND THEIR DEPTH. THE UPPER LEVEL PATTERN SHOWS THE FLOW SHIFTING TO THE SOUTHWEST ACROSS OUR AREA AS A STORM SYSTEM AND ITS TROUGH DEVELOP OFF THE WEST COAST THURSDAY. AS THE MAIN LOW APPROACHES THE PACIFIC NORTHWEST AND ITS ASSOCIATED TROUGH MOVE ASHORE FRIDAY A PIECE OF ENERGY FROM THE SOUTHERN PORTION OF THE TROUGH CAN BE SEEN MOVING TOWARD OR OVER THE AREA BY 00Z SATURDAY. LOOKS LIKE A SIMILAR SCENARIO THROUGH 00Z SUNDAY AND PERHAPS MONDAY. && .AVIATION... FOR THE 12Z TAF...NORTHWEST WINDS OF 20-30 KTS WITH HIGHER GUSTS WILL CONTINUE THROUGH 23Z OR SO AT BOTH SITES WITH ONLY SCATTERED CLOUDS IN THE 5-10K FT RANGE THROUGH THE DAY. AFTER 23Z WINDS WILL REMAIN OUT OF THE NORTHWEST AT SUSTAINED SPEEDS OF 15-20 KTS WITH LITTLE IN THE WAY OF CLOUDINESS EXPECTED. VFR CONDITIONS THROUGH THE TAF PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ DDT/DDT/DDT ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1204 AM EST MON DEC 31 2007 .AVIATION... LIGHT SNOW WILL END OVER SE MICHIGAN BY 09Z/4AM AND BE REPLACE BY STRATUS AND MVFR FOG FOR MUCH OF THE REST OF THE MORNING. THERE IS ALREADY A GENEROUS AMOUNT OF FOG AND LOW CLOUDS OVER SOUTHERN WISCONSIN AND NORTHERN ILLINOIS THAT IS SHOWN BY THE MODELS TO SLIDE INTO OUR AREA AND AND NORTH OF THE WEAK SURFACE TROUGH. MVFR CONDITIONS WILL THEN PERSIST INTO THIS AFTERNOON BEFORE GIVING WAY TO SOME SLIGHT VISIBILITY IMPROVEMENT. SNOW FROM THE NEXT LOW PRESSURE SYSTEM IS EXPECTED TO BEGIN DURING THE EVENING HOURS AND AFFECT MAINLY THE DETROIT AREA WITH SOLID ACCUMULATION DURING THE NIGHT. && .PREV DISCUSSION...ISSUED 817 PM EST SUN DEC 30 2007 UPDATE... MINOR BUT STILL WORTHY ADJUSTMENTS TO SNOW EXPECTATIONS FOR THE REST OF TONIGHT ARE COMING UP AS OUR HIGH POP LOW QPF SCENARIO CONTINUES TO UNFOLD. THE LEAD UPPER LEVEL DEFORMATION PATTERN BRUSHING OUR FAR EASTERN COUNTIES HAS A COUPLE MORE HOURS LEFT IN IT BEFORE FORCING TRANSITIONS TO THE WAVE SHEARING EASTWARD FROM THE CHICAGO AREA. THIS SYSTEM WILL BRUSH THE DETROIT AREA BUT MAINLY AFFECT THE INTERSTATE 69 CORRIDOR INTO THE OVERNIGHT HOURS. ALL OF THIS DYNAMIC FORCING IS ACTING IN A SIMILAR ENVIRONMENT OF LOW MOISTURE BUT ALSO LOW STATIC STABILITY OR EVEN SHALLOW LAYERS OF INSTABILITY IN THE MID LEVELS AS SHOWN IN MODEL CROSS SECTIONS. THE RESULTING MOISTURE WILL CONTINUE TO BATTLE DRY AIR IN THE LOW LEVELS, ESPECIALLY IN THE TRI CITIES, FOR THE DURATION OF THE EVENT. EXPECT THINGS TO TAPER OFF AROUND 3 AM AS THE UPPER WAVE SHEARS TO OUR EAST. UNTIL THEN, WE WILL HANG ON TO CATEGORICAL POPS A LITTLE FARTHER NORTH INTO FLINT AND A LONGER INTO THE NIGHT, BUT WITH SOME DURATION QUALIFIERS TO GO ALONG WITH ACCUMULATION LESS THAN AN INCH. PREV DISCUSSION...ISSUED 332 PM EST SUN DEC 30 2007 SHORT TERM...THROUGH TONIGHT HIGH POP/LOW QPF SNOW MINI-EVENT EXPECTED FOR THE SOUTHERN HALF OF THE FORECAST AREA TONIGHT...ROUGHLY SOUTH OF I-69. NORTH OF THERE...JUST SOME LIGHT SNOW SHOWERS. HIGHEST SNOW ACCUMULATIONS...ONLY ABOUT AN INCH...ARE EXPECTED TO OCCUR OVER THE FAR SOUTHEASTERN PORTION OF THE STATE...FROM ST CLAIR COUNTY SOUTHWARD DOWN TO MONROE COUNTY. UPPER TROUGH AXIS MOVING THROUGH THE CORN BELT THIS AFTERNOON WILL MOVE THROUGH THE GREAT LAKES DURING THE FIRST HALF OF NIGHT. WHILE MAIN SURFACE REFLECTION WILL STAY OVER THE CAROLINAS...PAST SEVERAL MODEL SUITES HAVE SHOWN A SECONDARY REFLECTION DEVELOPING OVER WEST VIRGINIA AND TRACKING UP THROUGH WESTERN PENNSYLVANIA DURING THE LATE EVENING. MSAS SURFACE ANALYSIS AND SURFACE OBSERVATIONS DO INDICATE THE PRESENCE OF THIS FEATURE...AND 12Z MODELS WERE DEFINITELY TOO WEAK WITH IT. ALREADY SOME EVIDENCE OF A DEFORMATION BAND FORMING ON THE NORTH SIDE OF THIS SYSTEM PER OBS AND SATELLITE IMAGERY...AND MODELS ARE IN GOOD AGREEMENT WITH BRINGING THIS DEFORMATION ZONE INTO SOUTHEAST MICHIGAN AFTER 00Z TONIGHT. SYSTEM WILL NOT HAVE MUCH TO WORK WITH AS JET DYNAMICS WILL REMAIN JUST TO OUR SOUTHEAST...AND NO DECENT INFLUX OF LOW LEVEL MOISTURE WILL OCCUR. WILL SEE SOME ISENTROPIC LIFT HOWEVER...AND FORCING DOES LOOK TO BE CENTERED IN THE DENDRITIC GROWTH ZONE ALLOWING FOR MAXIMUM CRYSTAL GROWTH. OVERALL...LIKE THE RUC AND NGM QPF FIELDS THE BEST. DID HOWEVER LEAN TOWARDS THE HIGHER END OF THE MODEL QPF FIELDS...GIVEN THAT THE MODELS ARE UNDERDONE WITH THE SYSTEM INTENSITY. WITH THE LOW CENTER ALREADY SO FAR TO OUR EAST SNOWFALL WILL BE LIGHT AND FAIRLY SHORT IN DURATION...MOSTLY OCCURRING WITHIN A 4 TO 6 HOUR WINDOW THIS EVENING. PRECIPITATION SHOULD BE OUT OF SOUTHEAST MICHIGAN BY 4 AM. IN THE WAKE OF THIS LITTLE SYSTEM...LOW CLOUDS AND MIST WILL LINGER THROUGH THE NIGHT. SOUTHWEST FLOW WILL ALSO BECOME ESTABLISHED LATE TONIGHT AS THE NEXT LOW PRESSURE SYSTEM OVER THE UPPER MIDWEST BECOMES BETTER ORGANIZED AND STARTS TO ADVANCE INTO THE WESTERN GREAT LAKES. LONG TERM... WATER VAPOR IMAGERY AND RUC ANALYSIS DEPICTING WEAK SHORTWAVE ENERGY EJECTING SOUTHEAST ACROSS THE PACIFIC NORTHWEST THIS AFTERNOON. THIS ENERGY WILL ORGANIZE INTO A STRONGER SHORTWAVE ACROSS THE PLAINS TONIGHT...AND EVENTUALLY INDUCE WEAK SFC CYCLOGENESIS AS IT PULLS TOWARD THE GREAT LAKES ON MONDAY. MODEL TRENDS SINCE THE 00Z CYCLE HAVE BEEN TOWARD A WEAKER AND MORE SOUTHERLY TRACK OF THE MAIN SFC LOW...WITH A SECOND WEAKER SFC REFLECTION INDICATED WITHIN THE UNPHASED FLOW ACROSS SOUTHERN CANADA. THE 12Z GFS...WITH SUPPORT FROM THE 12Z WRF-HEMI AND CANADIAN...TAKES THE LOW FROM CENTRAL IL ACROSS NORTHERN IN AND INTO LAKE ERIE. THE NAM REMAINS THE FURTHEST SOUTH...KEEPING A STRONGER/MORE COMPACT LOW ACROSS SOUTHERN IN/NORTHEAST OHIO. THE 12Z ECMWF APPEARS TO BE A GOOD COMPROMISE...MAINTAINING A SLIGHTLY MORE SOUTHERLY TRACK THAN THE GFS...WHILE ALLOWING FOR BETTER NORTHWARD EXPANSION OF THE MOISTURE/PCPN SHIELD INTO SOUTHEAST LOWER MI COMPARED TO THE VERY DRY LOOKING NAM. FORCING WILL BE LACKING INITIALLY...AND WILL PULL BACK ON POPS FOR THE MORNING HOURS. HOWEVER...BY LATE AFTERNOON/EVENING THE INCREASING LARGE SCALE ACCENT PROVIDED BY THE UPPER TROUGH AND WEAK LOW/MID LEVEL DEFORMATION WILL HELP OVERCOME A LIMITED MOISTURE SOURCE TO BRING SNOW TO ALL OF SOUTHEAST LOWER MI. MODELS INDICATE THE MAIN AXIS OF LARGE SCALE FORCING/OMEGA WILL EXIST JUST SOUTH OF THE STATE LINE...LEAVING THE HIGHEST QPF BANDS JUST OUT OF OUR AREA. HOWEVER...GIVEN THE ANTICIPATED LOW TRACK AND OVERALL VERTICAL MOTION/MOISTURE FIELDS...A BROAD 1-2 INCH SWATH OF SNOWFALL STILL SEEMS PLAUSIBLE BY 06Z MONDAY NIGHT...ESPECIALLY ACROSS THE SOUTHERN HALF. THE POTENTIAL DOES EXIST FOR HIGHER AMOUNTS APPROACHING 3 INCHES ACROSS THE SOUTHERN TWO TIER OF COUNTIES...AND WILL NEED TO MONITOR FOR A POSSIBLE NORTHWARD ADJUSTMENT IN THE TRACK AND BETTER FORCING. WHERE GOOD SYNOPTIC FORCING LACKS ACROSS THE THUMB REGION...SOME ADDITIONAL SNOWFALL MAY COME FROM LAKE EFFECT ENHANCEMENT. THE ONLY AREA THAT MAY STRUGGLE TO SEE MUCH SYNOPTIC ACCUMULATION WILL BE IN THE SAGINAW VALLEY...AND WILL SCALE BACK QPF/SNOW AMOUNTS SLIGHTLY HERE. 12Z MODEL SUITE REMAIN IN STRONG AGREEMENT AND CARRY GOOD RUN TO RUN CONTINUITY WITH THE PATTERN EVOLUTION BY MIDWEEK. THE WEAKER SYSTEM LIFTING THROUGH MONDAY WILL LEAD IN A STRONGER SHORTWAVE FOR TUESDAY...WITH THIS ENERGY CARVING OUT A DEEPER LONGWAVE TROUGH AND ALLOWING A BRIEF SHOT OF ARCTIC AIR TO SPILL IN FOR TUESDAY NIGHT/ WEDNESDAY. STRENGTHENING COLD AIR ADVECTION ON TUESDAY WITH 850 MB TEMPERATURES DROPPING BELOW -10C WILL CREATE MARGINALLY FAVORABLE CONDITIONS FOR LAKE ENHANCED SNOW SHOWERS DURING THE DAY. THE LATEST GFS INDICATING A NARROW CONVERGENCE ZONE DEVELOPING ACROSS THE EASTERN PORTION OF THE THUMB...WITH A SMALL WINDOW OF PREDOMINANT NORTH-NORTHEAST FLOW OVER LAKE HURON INCREASING THE POTENTIAL FOR HIGHER SNOW AMOUNTS IN THESE LOCATIONS LATE TUESDAY. MORE ORGANIZED ACTIVITY WILL DEVELOP BY TUESDAY EVENING AREAWIDE AS FORCING/CONVERGENCE INCREASES ALONG THE ARCTIC FRONTAL BOUNDARY DROPPING SOUTH ACROSS SOUTHERN MI...AND LIKELY POPS REMAIN APPROPRIATE FOR THIS PERIOD. OVERALL...ADDITIONAL ACCUMULATIONS UP TO 2 INCHES (HIGHEST NORTH) STILL SEEMS REASONABLE AREAWIDE...WITH LOCALLY HIGHER AMOUNTS POSSIBLE ESPECIALLY IN THE FAVORED LAKE ENHANCED AREAS ACROSS THE THUMB. ARCTIC AIRMASS WILL SETTLE OVERHEAD BRIEFLY FOR WEDNESDAY...WITH LINGERING SCATTERED SNOW SHOWERS. BASED ON PROJECTED 850 MB/ THICKNESS TRENDS...TEMPERATURES WILL LIKELY HOLD STEADY OR SLOWLY FALL...AND NOT REACH MUCH ABOVE THE LOWER 20S. AT LEAST PARTIAL CLEARING WEDNESDAY NIGHT...COMBINED WITH A WEAKENING GRADIENT WITH HIGH PRESSURE BUILDING ACROSS THE OHIO VALLEY...WILL BRING THE COLDEST NIGHT OF THE FORECAST PERIOD. GOING FORECAST WITH LOWS BOTTOMING OUT IN THE 5-10F RANGE STILL LOOKING GOOD FOR THURSDAY MORNING. BIG PATTERN CHANGE FOR THE LATTER HALF OF THE FORECAST PERIOD...AS MODEL CONSENSUS PLACES THE GREAT LAKES WITHIN AN INCREASINGLY DEEP SOUTHWEST FLOW...BETWEEN STRENGTHENING RIDGING ACROSS THE EAST COAST AND A LONGWAVE TROUGH OVER THE WESTERN THIRD OF THE CONUS. THIS WILL LEAD TO A PRONOUNCED WARMUP BY THE WEEKEND...WITH 850 MB TEMPS CLIMBING INTO THE 5-10C RANGE BY SUNDAY. IT WILL TAKE SOME TIME TO SCOUR OUT THE ARCTIC AIR INITIALLY...AND WILL CONTINUE TO TEMPER THE WARMUP ON THURSDAY...AS THE COLD MORNING START AND SNOW COVER POTENTIAL WILL CERTAINLY COUNTER ANY INCREASE IN WARM AIR ADVECTION/ RISING THICKNESSES. HOWEVER...BY THE WEEKEND EXPECT TEMPERATURES TO CLIMB WELL ABOVE NORMAL...WITH HIGHS ON SUNDAY POTENTIALLY APPROACHING 50F ACROSS THE SOUTH. INCREASING ISENTROPIC ACCENT AND THE PASSAGE OF A WEAK SHORTWAVE WILL BRING THE NEXT CHANCE OF PCPN BY SATURDAY...WITH THE THERMAL PROFILES LOOKING MORE LIKE ALL RAIN. MARINE... AN AREA OF LOW PRESSURE WILL BECOME ORGANIZED OVER THE UPPER MIDWEST TONIGHT. THIS SYSTEM WILL DEEPEN AS IT MOVES ACROSS THE SOUTHERN GREAT LAKES MONDAY NIGHT...AND CONTINUE TO INTENSIFY THROUGH TUESDAY AS IT TRACKS INTO NEW ENGLAND. MEANWHILE...A VERY LARGE AND STRONG AREA OF HIGH PRESSURE WILL BUILD IN ITS WAKE TUESDAY OVER THE CENTRAL PLAINS. WITH OUR AREA IN THE CENTER OF THESE TWO STRENGTHENING SYSTEMS...A PROLONGED PERIOD OF GUSTY WINDS WILL OCCUR OVER ALL MARINE AREAS TUESDAY MORNING THROUGH WEDNESDAY EVENING. WINDS ARE EXPECTED TO REMAIN BELOW GALE STRENGTH...BUT SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....BT UPDATE.......BT SHORT TERM...HLO LONG TERM....MR MARINE.......HLO YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 256 AM CST MON DEC 31 2007 .DISCUSSION... NARROW SNOW BAND EXPECTED TO CONTINUE ACROSS FAR SOUTHERN COUNTIES IN NEB IN ASSOCIATION WITH ENTRANCE REGION OF FAST MOVING JET STREAK. STRONGEST 88D RETURNS LINE UP WELL WITH RUC 300MB DIVERGENCE...HOWEVER SO FAR ONLY MID LEVEL CLOUDS REPORTED ON SFC OBS...BUT A FEW COUNTIES IN NERN KS NOW REPORTING BRIEF LIGHT SNOW. EXPECT LESS THAN AN INCH OF ACCUMULATION THROUGH 12Z MAINLY SOUTH OF INTERSTATE 80...WITH MOST AREAS RECEIVING JUST A DUSTING DUE TO LACK OF GOOD MOISTURE. FORCING IS QUICK TO MOVE EAST OF THE FORECAST AREA BY 18Z AS UPPER SHORTWAVE DIGS INTO NRN MO. ANOTHER WEAK WAVE BEHIND THIS INITIAL WAVE IS QUICK TO MOVE INTO NERN NEB THIS AFTERNOON AND COULD SUPPORT ENOUGH LIFT TO PRODUCE AREAS OF LIGHT SNOW OR FLURRIES ACROSS THE NORTHERN HALF OF FORECAST AREA. HAVE SIGNIFICANTLY REDUCED POPS FOR THE NEXT 24 HOURS OF THE FORECAST DUE TO LACK OF PROLONGED FORCING AND MOISTURE. AT THE SFC...COLD FRONT DRAPED ACROSS CNTRL NEB WL CONTINUE TO MOVE EWD TODAY. BEHIND THE BOUNDARY...DESCENT MIXING IS TAKING PLACE AND SO HAVE BOOSTED HIGHS FOR TODAY TO ACCOUNT FOR THIS. SFC PRESSURE GRADIENT WL CONTINUE TO INCREASE THROUGHOUT THE DAY AS 1050MB HIGH BUILDS OVER THE COLORADO ROCKIES. MEANWHILE...500MB CLOSED LOW AND ASSOCIATED TROF WITH SLUG OF ARCTIC AIR WL DIVE OUT OF ERN DAKOTAS LATE TONIGHT AND BRUSH NERN NEB AND NWRN IA. THIS WL DRAG ARCTIC FRONT DOWN WITH POCKET OF -20C 850MB AIR. A FEW FLURRIES ARE CERTAINLY POSSIBLE WITH THE PASSAGE OF THE TROF HOWEVER AIRMASS REMAINS QUITE DRY AND SO DOUBTFUL OF ANY ACCUMULATING SNOW. WITH A CONTINUED STRONG SFC GRADIENT AND 850MB WINDS NEAR 40-50KTS...WL SEE SOME VERY COLD TEMPS AND WIND CHILL READINGS DURING THE DAY TUESDAY. SFC HIGH PRESSURE RIDGE WL BUILD IN WED MORNING AND NEGATIVE SINGLE DIGITS ARE QUITE LIKELY AS WINDS DIE OFF. GENERAL THEME OF REMAINDER OF FORECAST IS DRY AND MUCH WARMER AS AMPLIFIED UPPER RIDGE BUILDS ACROSS THE CENTRAL CONUS. WL BE A CHALLENGING TEMP FORECAST FOR THE EXTENDED AS SNOW COVER AND POSSIBLE STRATUS DECK INFLUENCE DAILY MAXES. && .AVIATION... FOR TAF SITES KOFK/KLNK/KOMA THE MAIN FORECAST CONCERN IS A BAND OF SNOW MOVING THROUGH SE NEB THIS MRNG. THIS COULD PRODUCE BRIEF IFR VSBY AT LNK THROUGH 13Z. MEASURABLE SNOW IS UNLIKELY FOR ANY OF THE SITES AFTER THIS. HOWEVER...INCREASING NW WINDS WILL BRING A STRENGTHENING PUSH OF ARCTIC AIR ACROSS THE AREA THIS AFTN AND TNGT. THIS WILL LIKELY PRODUCE SOME MVFR STRATOCU CIGS AND SCT SNOW SHWRS WITH MINOR VSBY REDUCTIONS. SFC WINDS WILL STRENGTHEN TO 17-25KT BY ARND 18Z AND REMAIN IN THAT RANGE THROUGH 12Z FRI. A FEW GUSTS 30-35 KT ARE LIKELY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ GRIFFIS/POLLACK ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBUQUERQUE NM 945 PM MST SUN DEC 30 2007 .UPDATE... DECIDED TO CANCEL THE WIND ADV FOR ZONE 2. WINDS ALOFT AS ADVERTISED ON THE 02Z RUC13/00Z NAM40 HAVE FAILED TO TRANSLATE TO THE SURFACE ACROSS THE ENTIRE ADV AREA. HOWEVER...REPORTS FROM SPOTTERS ALONG INTERSTATE 25 NEAR SPRINGER AND WAGON MOUND HAVE SEEN BLOWING DIRT AND SNOW WITH STRONG WESTERLY WINDS. STRONGEST WINDS APPEAR TO BE FARTHER TO THE NORTH STILL OVER CENTRAL CO AND THEY WILL CONTINUE SAGGING SOUTH OVERNIGHT. LOWERED SKY COVER TO CLEAR OVER THE CWA WITH MOSTLY CLOUDY ALONG THE WEST SLOPES OF THE SAN JUAN AND SANGRE DE CRISTO MOUNTAINS. ADJUSTED MAX TEMPS DOWN MONDAY AS 700MB TEMPS COOL ANOTHER 6 TO 12 DEGREES FROM TODAY. NEW YEARS EVE LOOKS TO BE EXTREMELY COLD OVER THE NORTHERN MOUNTAINS WITH TEENS TO 20S BELOW ZERO POSSIBLE AND WIDESPREAD SINGLE DIGITS AND TEENS ELSEWHERE. GUYER && .PREV DISCUSSION...257 PM MST SUN DEC 30 2007... CURRENTLY...NORTHWEST FLOW ALOFT OVER NEW MEXICO BETWEEN RIDGE POKING UP FROM EAST PACIFIC OCEAN WATERS OFF NORTHERN CALIFORNIA TO THE MACKENZIE RIVER DELTA IN ARCTIC NORTHWEST CANADA...AND TROUGH SWINGING EAST FROM CURRENT AXIS FROM NORTHERN MANITOBA SOUTH AND EAST TO CENTRAL ALABAMA. MAIN 300 MB JET STREAK RUNNING FROM PACIFIC NORTHWEST TO CENTRAL COLORADO...WITH A LOBE OF FAST FLOW JUST NOSING INTO NEW MEXICO FROM SOUTHERN NEVADA. WIND SPEEDS HAVE BEEN A LITTLE TARDY ON COMING UP THIS AFTERNOON...BUT CLINES CORNERS REMAINS THE WINDY WINNER IN TORRANCE COUNTY...WITH BROAD AREA OF GUSTS IN THE 30S AND 40S MPH ALONG AND EAST OF THE NORTHERN AND CENTRAL MOUNTAIN CHAIN. WITH SECONDARY SPEED LOBE STILL UPSTREAM ALOFT...WILL ALLOW NORTHERN MOUNTAINS AND FAR EASTERN PLAINS WIND ADVISORIES TO CONTINUE THROUGH 11 P.M. MST AS SCHEDULED...BUT EXTEND ADVISORIES THROUGH 5 A.M. MST MONDAY MORNING FOR THE SANGRE DE CRISTO MOUNTAINS...NEIGHBORING NORTHEAST HIGHLANDS...THE EAST CENTRAL PLAINS...AND THE SANDIA AND MANZANO PASSES. ADVISORY WILL CALL OUT HIGH PEAKS...GAPS...AND PASSES AS PARTICULARLY WINDY AREAS. DESPITE DYNAMIC EXCITEMENT ALOFT...SURFACE PRESSURE FIELD IS PRETTY FLAT WITH HIGH PRESSURE CENTERING UP OVER THE FOUR CORNERS AND FIRST INKLING OF DEEPENING TROUGH OVER THE TEXAS PANHANDLE. WILL THUS PLAN ON CONTINUED VERTICAL DECOUPLING OF THE LOWER ATMOSPHERE...AND MAINTAIN WIND EMPHASIS ON HIGHER ELEVATIONS THIS ROUND. WITH DYNAMICS STILL ACTIVE ALOFT...QUICK HITTER SHOTS OF SNOW AND CLOUD IN THE CARDS FOR THE NORTHERN MOUNTAINS THROUGH THE DAY TOMORROW...WITH THIS FOCUS FOR ISOLATED ACTIVITY CREEPING SLOWLY TO THE NORTHEAST PLAINS DURING THE DAY ON MONDAY. MODELS...GOOD CONSENSUS WITH PLAUSIBLE AND REASONABLE SOLUTION...MOVING AMPLIFYING WEST COAST RIDGE TOWARD NEW MEXICO AND SUPPORTING WARMING TREND THROUGH MIDWEEK IN ADVANCE OF ARRIVAL OF NEXT WEATHER SYSTEM DUE IN TO THE FOUR CORNERS LATE THURSDAY NIGHT. SHORT TERM...TONIGHT AND MONDAY...FAST FLOW ALOFT CONTINUING THROUGH THE OVERNIGHT...WITH WIND ADVISORIES FLYING THROUGH EARLY MORNING FOR SANGRE DE CRISTOS...NORTHEAST HIGHLANDS...EAST CENTRAL PLAINS...AND SANDIA AND MANZANO MOUNTAIN GAPS. WINDS SHOULD COME DOWN WELL BY MONDAY MORNING...AS SUPPORT ALOFT MOVES OFF TO THE EAST AND LAST OF THE DYNAMICS TOUCHES OFF SOME FAREWELL ISOLATED SNOW SHOWERS AS COLD FRONT DROPS SOUTHWARD ACROSS THE STATE DURING THE DAY. COLDER AIR AND BREEZY LOW LEVEL FLOW FROM THE NORTH WILL DELAY START TO THE WARMING TREND. LONG TERM...TUESDAY THROUGH THURSDAY...RIDGE AMPLIFYING OVER WESTERN NEW MEXICO EARLY TUESDAY WILL OVERSPREAD THE STATE BY AFTERNOON FOR RETURN TO CLEAR SKIES AND WARMING TREND FOR THE DAY. SURFACE HIGH PRESSURE BUILDING IN WAKE OF DEPARTING TROUGH ALOFT WITH DEEPENING SURFACE LOW ON UPSTREAM SIDE OF THE RIDGE OVER NORTHWEST MEXICO WILL SHIFT WINDS AROUND TO THE EAST AND SOUTHEAST BY TUESDAY AFTERNOON. INTO WEDNESDAY...QUICK SHOT DISTURBANCE BARRELING OUT OF BAJA CALIFORNIA MAY INTERRUPT SUNSHINE AND THROW CLOUDS ACROSS THE STATE FOR MIDWEEK...BUT VERY SPOTTY PRECIPITATION WITH THIS...AND MOST OF THIS OVER THE WESTERN MOUNTAINS. CONTINUED WARMING TREND WILL START TO PUSH HIGH TEMPERATURES ABOVE NORMAL. INTO THURSDAY...WEATHER SYSTEM MAKING LANDFALL OVER SOUTHERN CALIFORNIA WILL BACK FLOW ALOFT TO THE SOUTHWEST...INTRODUCING THE FIRST OF THE HIGHER CLOUDS TO THE WESTERN SIDE OF THE STATE DURING THE DAY. STORM WILL CROSS INTO WESTERN NEW MEXICO LATE THURSDAY NIGHT TO KICK OFF SOME LESS THAN IDEAL TRAVEL WEATHER HEADING INTO THE FINAL HOLIDAY TRAVEL WEEKEND. HAVE ALREADY ISSUED SPECIAL WEATHER STATEMENT ADVISING CUSTOMERS WITH TRAVEL PLANS TO STAY CLOSE TO FORECASTS FOR FRIDAY HEADING INTO THE WEEKEND...WITH MUCH UNCERTAINTY REMAINING IN STORM TRACK AND EVENTUAL PRECIPITATION PLACEMENT. SHY .AVIATION...WINDS ALOFT INCREASING TONIGHT MUCH OF NORTH AND CENTRAL NM WITH SOME MOUNTAIN WAVE INDUCED TURBULENCE A GOOD POSSIBILITY TO LEE OF CENTRAL MOUNTAIN CHAIN ALONG WITH STRONG WINDS OVER HIGHER RIDGES AND NEARER THE SURFACE IN VICINITY OF THE WAVE TROUGHS. THESE WINDS AND TURBULENCE SHOULD DECREASE SOMEWHAT THROUGH THE MORNING HOURS MONDAY. WEAK BACK DOOR COLD FRONT STILL EXPECTED TO ENTER THE NORTHEAST THIRD OR SO OF THE STATE LATE TONIGHT BUT MAY WELL BE A LITTLE WEAKER THAN EARLIER EXPECTED. VFR CONDITIONS EXPECTED ACROSS MOST OF AREA THROUGH AND BEYOND MONDAY THOUGH SOME LOCALIZED MOUNTAIN TOP OBSCURATION...ISOLATED LIGHT FLURRIES AND MARGINALLY IFR CONDITIONS POSSIBLE AT TIMES ACROSS NW MOUNTAINS TONIGHT INTO MONDAY MORNING. NEXT AVIATION DISCUSSION SCHEDULED FOR 10Z. && .PRELIMINARY POINT TEMPS/POPS... FARMINGTON...................... 19 32 6 36 / 0 0 0 0 GALLUP.......................... 14 37 2 40 / 0 0 0 0 GRANTS.......................... 17 39 1 42 / 0 0 0 0 GLENWOOD........................ 26 52 24 53 / 0 0 0 0 CHAMA........................... 5 20 -11 34 / 10 10 0 0 LOS ALAMOS...................... 16 30 2 36 / 0 0 0 0 RED RIVER....................... 3 17 -12 29 / 10 10 0 0 TAOS............................ 10 26 -11 32 / 0 0 0 0 SANTA FE........................ 17 30 7 34 / 0 0 0 0 SANTA FE AIRPORT................ 20 34 5 32 / 0 0 0 0 ESPANOLA........................ 20 35 2 35 / 0 0 0 0 ALBUQUERQUE HEIGHTS............. 26 40 16 39 / 0 0 0 0 ALBUQUERQUE VALLEY.............. 23 42 12 36 / 0 0 0 0 ALBUQUERQUE FOOTHILLS........... 25 38 14 41 / 0 0 0 0 ALBUQUERQUE WEST MESA........... 25 41 13 40 / 0 0 0 0 SOCORRO......................... 24 47 19 42 / 0 0 0 0 SANDIA PARK/CEDAR CREST......... 20 34 9 39 / 0 0 0 0 MORIARTY/ESTANCIA............... 21 34 10 33 / 0 0 0 0 CARRIZOZO....................... 27 45 20 42 / 0 0 0 0 RUIDOSO......................... 30 41 17 38 / 0 0 0 0 RATON........................... 15 33 -1 31 / 0 10 5 0 LAS VEGAS....................... 19 28 5 32 / 0 5 0 0 ROY............................. 22 34 12 35 / 0 10 10 0 CLAYTON......................... 21 36 10 34 / 0 0 0 0 SANTA ROSA...................... 27 41 13 41 / 0 0 0 0 TUCUMCARI....................... 28 40 12 40 / 0 0 0 0 FORT SUMNER..................... 26 42 15 40 / 0 0 0 0 CLOVIS.......................... 26 41 14 41 / 0 0 0 0 PORTALES........................ 26 43 13 42 / 0 0 0 0 ROSWELL......................... 29 50 19 44 / 0 0 0 0 && .ABQ WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 5 AM MST MONDAY FOR THE FOLLOWING ZONES... NMZ004-005-010>012. && $$ GUYER nm AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 1005 AM EST MON DEC 31 2007 .DISCUSSION... WEAK HIGH PRESSURE WILL REMAIN IN CONTROL OF THE FORECAST AREA THROUGH THE EVENING HOURS. COLD FRONT HAS STALLED TO OUR SOUTHEAST ACROSS THE CENTRAL FL PENINSULA THIS MORNING. HAVE MADE A FEW MINOR ADJUSTMENT TO THE FORECAST...ESPECIALLY OVER THE EASTERN FLORIDA BIG BEND. ISENTROPIC ANALYSIS IS SHOWING INCREASING UPGLIDE ALONG THE 295-300K SURFACES THIS AFTERNOON AND INTO THE EVENING TO THE NORTH OF THE SURFACE BOUNDARY. CONDENSATION PRESSURE DEFICITS BELOW AROUND 700MB ARE QUITE LOW RESULTING IN ONLY WEAK LIFT NEEDED TO REACH SATURATION. IN ADDITION...RUC IS SHOWING A WEAK DISTURBANCE BETWEEN 500-300MB CROSSING THE NORTHERN GULF WHICH SHOULD HELP ADD A SMALL AMOUNT OF SYNOPTIC LIFT TO THE PICTURE OVER THESE AREAS. THIS DISTURBANCE COULD BE SEEN EARLIER THIS MORNING CROSSING THROUGH SOUTHEAST TEXAS WITH A SLIGHT BACKING IN THE PROFILER WIND DATA. CROSS SECTION FORECASTS FROM JUST SOUTHEAST OF KTLH TO KCTY LATER TODAY INTO AT LEAST THE FIRST HALF OF THE EVENING ARE SHOWING A FAIRLY IMPRESSIVE OMEGA BULLSEYE IN THE LOWER LEVELS. WHILE IMPACTS ARE EXPECTED TO BE MINOR...CAN NOT RULE OUT A FEW SHOWERS/SPRINKLES SOUTH AND EAST OF A LINE FROM KAAF TO KTLH IN ADDITION TO SKIES REMAINING MOSTLY CLOUDY. WITH THE CLOUDS AND SOME LIGHT PRECIP POSSIBLE ALSO LOWERED HIGHS ACROSS THIS AREA BY A COUPLE OF DEGREES...MAINLY DOWN INTO THE MIDDLE 60S. LIFT RAPIDLY DIMINISHES BY THE LATER EVENING HOURS AND HAVE ALL SHOWERS/SPRINKLES ENDING BY MIDNIGHT (LIKELY A BIT EARLIER FROM KAAF TO KTLH). FORECAST ATTENTION WILL THEN SHIFT TO THE APPROACH OF A STRONG ARCTIC COLD FRONT LATER TONIGHT FROM THE NORTHWEST. LATEST GUIDANCE BRINGS THE FRONT TO AROUND KDHN AND KABY AROUND 09Z AND THEN EXITS THE FRONT SOUTH OF THE COASTAL WATERS AND KCTY BETWEEN 14-15Z TUESDAY MORNING. ALTHOUGH HIGHS WILL STILL BE IN THE 50S ON TUESDAY WITH THE COLDEST AIR NOT ARRIVING UNTIL TUESDAY NIGHT...GUSTY NORTHWEST WINDS WILL MAKE IT FEEL COOLER. LATEST GUIDANCE IS SHOWING 850MB TEMPS DROPPING TO BETWEEN -8 AND -13C FROM SOUTH TO NORTH BY SUNRISE WEDNESDAY MORNING. THIS IS A FAIRLY IMPRESSIVE COLD AIRMASS FOR OUR NECK OF THE WOODS. LOOKING AT IT STATISTICALLY...THESE 850MB TEMPS ARE -4.0 TO -4.5 STANDARD DEVIATIONS FROM CLIMATOLOGY. TO PUT THIS IN PLAIN WORDING...A 4.0 STANDARD DEVIATION EVENT HAS A LESS THAN A ONE HALF PERCENT (< 0.5%) PROBABILITY OF OCCURRENCE. SO...ALTHOUGH WE HAVE CERTAINLY SEEN COLDER AIRMASS IN THE PAST...THIS IS STILL A VERY RARE OCCURRENCE. LOOKING FOR A WIDESPREAD ADVECTION FREEZE TUESDAY NIGHT INTO WEDNESDAY MORNING AND WILL MONITORING CLOSELY FOR POSSIBLE HARD FREEZE CONDITIONS...ESPECIALLY OVER NORTHERN PORTIONS OF THE AREA. WITH THE LOWER LEVEL ATMOSPHERIC COLUMN AS COLD AS EXPECTED ON WEDNESDAY...CURRENT FORECAST HIGHS IN THE MIDDLE 40S MAY BE ON THE OPTIMISTIC SIDE AND WILL TAKE A CLOSE LOOK AT THESE HIGHS WITH THE AFTERNOON FORECAST PACKAGE. ANOTHER WIDESPREAD FREEZE IS EXPECTED WEDNESDAY NIGHT INTO THURSDAY MORNING WITH HARD FREEZE CONDITIONS POSSIBLE...IF NOT LIKELY...AWAY FROM THE IMMEDIATE COAST. && .MARINE... NORTHEAST FLOW OVER THE FORECAST WATERS BETWEEN 10 AND 15 KNOTS SHOULD CONTINUE INTO THE EARLY AFTERNOON BEFORE SETTLING DOWN TO AROUND 10 KNOTS. FLOW WILL COME AROUND BY LATE THIS EVENING TO THE WEST AND NORTHWEST BETWEEN 10 AND 15 KNOTS IN ADVANCE OF A STRONG ARCTIC COLD FRONT. THIS FRONT PUSHES THROUGH THE WATERS TUESDAY MORNING WITH WIND AND SEAS RAPIDLY BUILDING TO ADVISORY LEVELS FOR ALL LEGS. AS STRONG HIGH PRESSURE BUILDS DOWN INTO THE SOUTHERN PLAINS TO OUR WEST THE COMBINATION OF A TIGHT PRESSURE GRADIENT AND STRONG COLD AIR ADVECTION WILL INCREASE WINDS EVEN FURTHER TUESDAY EVENING AND OVERNIGHT WITH SUSTAINED FLOW BETWEEN 25 AND 30 KNOTS POSSIBLE OVER A LARGE AREA. IT IS VERY POSSIBLE THAT GUSTS...OR EVEN FREQUENT GUST TO GALE FORCE WILL OCCUR TUESDAY NIGHT INTO WEDNESDAY MORNING. ADVISORY LEVEL WINDS AND SEAS WILL CONTINUE INTO WEDNESDAY NIGHT BEFORE SUBSIDING TO THE CAUTIONARY RANGE DURING THURSDAY AS HIGH PRESSURE SLIDES TO OUR NORTH. && .AVIATION... THE FOG AT KDHN AND KABY IS FORECAST TO DISSIPATE BY MID TO LATE MORNING. OTHERWISE...PREVAILING VFR CONDITIONS ARE FORECAST THROUGH THIS EVENING...BUT PERIODS OF MVFR CIGS ARE POSSIBLE AT KVLD. -SHRA WILL BE POSSIBLE AT KTLH AND KVLD...BUT CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE THEIR MENTION IN THE TAFS...AND IT IS UNLIKELY THERE WILL BE ANY SIGNIFICANT IMPACT TO OPERATIONS. WINDS WILL BE OUT OF THE E TO NE LESS THAN 10 KT. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 62 42 58 25 47 / 15 15 0 0 0 PANAMA CITY 62 46 56 30 47 / 0 0 0 0 0 DOTHAN 64 37 56 24 46 / 0 0 0 0 0 ALBANY 64 38 57 25 45 / 0 0 0 0 0 VALDOSTA 62 43 59 27 46 / 15 15 0 0 0 CROSS CITY 65 52 62 28 49 / 25 20 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 12 PM EST /11 AM CST/ TO 7 PM EST /6 PM CST/ TUESDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN... DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION...FOURNIER REST OF DISCUSSION...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1033 AM EST MON DEC 31 2007 .UPDATE...FAIRLY QUIET DAY ON TAP THROUGHOUT NORTHERN MICHIGAN... WITH THE EXCEPTION OF LINGERING LAKE EFFECT BAND ALONG/SOUTH OF THE STRAITS WHICH REMAINS THE PRIMARY FORECAST CHALLENGE. BAND REALLY WENT TO TOWN OVERNIGHT OWING TO ONSET OF DEEP SYNOPTIC MOISTURE IN ADVANCE OF WEAK SHORTWAVE PROGRESSING THROUGH WISCONSIN AS WELL AS PRONOUNCED 1000-850MB CONVERGENCE AXIS RUNNING THE LENGTH OF THE LAKE. BAND HAS SINCE WEAKENED WITH SOME DISRUPTION OF THE LOW LEVEL FLOW PER EARLY MORNING ONSET OF LAND BREEZE AS WELL AS PASSAGE OF WEAK UPPER WAVE AND LOSS OF -DIVQ. HOWEVER...OVERALL SFC FLOW REMAINS QUITE CONVERGENT PER RECENT OBS AND LATEST RUC/NAM PROGS THROUGH 18Z...AND WITH DELTA T/S MORE THAN SUFFICIENT (MID TEENS) AND INVERSION HEIGHTS NEARLY NON-EXISTENT IN THE PRESENCE OF STEEP LAPSE RATES (850-500MB RATES RUNNING SOME 7.5C/KM)...FORESEE NO REASON WHY SOME WEAK LAKE BANDING WON/T CONTINUE INTO THE AFTERNOON FOR THE TIP OF THE MITT COUNTIES. THUS GOING ADVISORY LOOKS LIKE A GOOD DEAL AS A FEW SPOTS (MAINLY EMMET COUNTY) COULD PICK UP A COUPLE FRESH INCHES INTO EARLY AFTERNOON BEFORE OVERALL PARAMETERS ON THE DECLINE PER INFLUX OF SLIGHTLY WARMER AIR ALOFT AND SHIFTING LOW LEVEL FLOW REGIME AS OHIO VALLEY STORM BEGINS TO TAKE SHAPE. ELSEWHERE...EARLY MORNING SYNOPTIC SNOW JUST ABOVE OVER AS WEAK 280-285K ISENTROPIC UPGLIDE WEAKENING WITH THE PASSAGE OF VORT AND DEPTH OF MOISTURE SHALLOWING. GIVEN LATEST RADAR TRENDS WILL JUST CALL IT FLURRIES FOR THE REMAINDER OF THE MORNING WITH THE EXCEPTION OF EASTERN UPPER WHERE WILL MAINTAIN SCATTERED LIGHT SNOW WITH MOISTURE DEPTH HOLDING FIRM PER FORECAST RAOBS. OTHERWISE...A MAINLY CLOUDY DAY ON TAP AREAWIDE...THOUGH COULD SEE A FEW BREAKS THROUGH THE DAY (ALREADY ONGOING ACROSS NORTHEAST LOWER WHERE FLOW WEAKLY DOWNSLOPE) BUT LIKELY NOT MUCH PER RENEWED PUSH OF MID/HIGH CLOUDS OFF TO THE SOUTH AND RESIDUAL THERMAL TROUGHING HANGING OUT OVERHEAD. ONE FINAL NOTE...HAVE ADDED MENTION OF PATCHY FREEZING FOG FOR MAINLY THE HIGHER TERRAIN THROUGH NOON AS OBS CONTINUE TO SHOW WIDESPREAD LIGHT FOG IN PLACE ALL THROUGH THE UPPER MIDWEST WITH PUSH OF WEAK THETA-E ADVECTION UP OVER SNOWPACK AND SOME HELP LOCALLY WITH SOUTHWEST FLOW RUNNING UP INTO THE HIGHER TERRAIN. HAVE ALREADY SEE LIGHT RIMING UP HERE ON THE HILL AND SUSPECT SIMILAR CONDITIONS IN PLACE CENTRAL CWA. LATEST NAM 30AGL COND PRES PLOTS SEEM TO HAVE A GOOD HANDLE ON THIS POTENTIAL...WITH SOME LOSS EXPECTED BY THE AFTERNOON AS SFC TEMPS CONTINUE TO WARM...THOUGH INTERESTING TO NOTE LATEST MAV GUIDANCE HANGS THE (RELATIVELY) LOW VISBYS IN THROUGH MUCH OF THE DAY FOR INTERIOR COUNTIES. LAWRENCE && .AVIATION...EXPECT PRIMARILY VFR CEILINGS FOR KTVC/KAPN THROUGH THE AFTERNOON...WITH MVFR CEILINGS/VISBYS AROUND KPLN AS SOUTHWEST FLOW LAKE EFFECT SNOW CONTINUES TO ADVANCE UP THE LAKE MICHIGAN SHORELINE. WINDS THROUGH THE NEXT 12 HOURS WILL REMAIN QUITE LIGHT...SHIFTING FROM THE SOUTH/SOUTHWEST TO A MORE NORTHERLY DIRECTION LATE TONIGHT. LAWRENCE && .PREV DISCUSSION... /ISSUED 426 AM EST MON DEC 31 2007/ DISCUSSION...NEW LONG WAVE TROUGH DIGGING TOWARD 150W EARLY THIS MORNING WILL SET THE STAGE FOR A SHOT OF COLD AIR FOR THE WESTERN LAKES TO USHER IN THE NEW YEAR. THIS COLD PERIOD WILL BE SHORT LIVED HOWEVER...WITH BIG TIME HEIGHT RISES AND SOUTHWESTERLY FLOW ALOFT SETTING UP FOR THE LATTER HALF OF THE WEEK. SO LOOKING AT A WARM UP AKIN TO WHAT OCCURRED DURING THE EXACT SAME TIME PERIOD ONE YEAR AGO. FORECAST PROBLEMS IN THE NEAR TERM WILL DEAL FIRST WITH A NASTY LOOKING SNOW BAND OVER NORTHERN LAKE MICHIGAN. FOCUS THEN TURNS TO TWO SHORT WAVES ROTATING THROUGH MEAN CENTRAL NORTH AMERICAN MEAN TROUGH POSITION. ONE WAVE SLIDING INTO NE/KS EARLY THIS MORNING... AND WILL ZIP THROUGH THE OHIO RIVER VALLEY TONIGHT. WILL NEED TO EVALUATE SNOW THREAT WITH THIS SYSTEM...EVEN THOUGH THE BULK OF THE EFFECTS WILL BE SOUTH OF THE FORECAST AREA. A SECOND WAVE SPINNING ITS WAY OUT OF NORTHERN MANITOBA PER WATER VAPOR IMAGERY WILL DIG SOUTHEAST INTO THE OHIO VALLEY AND MID ATLANTIC IN THE TUESDAY/ WEDNESDAY TIME FRAME AS LONG WAVE TROUGH CONTINUES TO TRANSLATE EASTWARD. THIS LATTER WAVE WILL HELP PULL COLDER AIR ACROSS THE GREAT LAKES THROUGH THE MIDWEEK PERIOD...AND WILL GET THE LAKE EFFECT MACHINE GOING AGAIN LATER TUESDAY INTO MIDWEEK. FORECAST EVOLUTIONS IS SOMEWHAT COMPLEX WITH DECENT POTENTIAL FOR SNOWFALL TUESDAY. MORE ON THAT BELOW. TODAY/TONIGHT...AT THE ONSET THIS MORNING...LIGHT SNOW AND FLURRIES WERE FALLING ACROSS NORTHERN LOWER...WITH A FOCUSED AREA OF CONVERGENCE RESULTING IN A STRONG SNOW BAND OVER NORTHERN LAKE MICHIGAN FROM THE MANITOU AND FOX ISLANDS NORTHEAST INTO THE STRAITS AREA. RADAR RETURNS ARE IMPRESSIVE...WITH POCKETS OF 30-35 DBZ RETURNS WITH RADAR ESTIMATES OF 1-2 INCH/HOUR SNOWFALL RATES. FORTUNATELY...MUCH OF THIS IS OFFSHORE THOUGH THE NORTHERN END IS POKING INTO SOUTHERN MACKINAC COUNTY. THIS BAND IS ACTUALLY JUST THE NORTHER END OF A BAND THAT SNAKES ITS WAY BACK INTO SOUTHERN LAKE MICHIGAN...WITH RADAR INDICATIONS OF ONE OR MORE MESOSCALE VORTICES SPINNING ALONG THIS LINE OF CONVECTION ACROSS CENTRAL AND SOUTHERN LAKE MICHIGAN. ON THE LARGE SCALE...SYNOPTIC LIGHT SNOW ASSOCIATED WITH NORTHERN FRINGES OF SMALL SCALE VORT CENTER NOTED ON WATER VAPOR SLIDING ACROSS FAR SOUTHERN LOWER...PROBABLY SOME CONTRIBUTION FROM ANOTHER MID LEVEL WAVE OVER CENTRAL WI. 00Z UPPER AIR ANALYSES/SOUNDINGS SHOW DRIER AIR ACROSS IA/MO/IL THAT MOVE INTO LOWER MI LATER TODAY...WHICH COMBINED WITH LOSS OF FORCING SHOULD CONFINE CURRENT LIGHT SNOW PATTERN TO THE FIRST HALF OF THE DAY FOR THE MOST PART. IN ADDITION TO THE SYNOPTIC SNOW...REMNANTS OF THE SOUTHERN PORTION OF THE AFOREMENTIONED LAKE MICHIGAN BAND WILL BRING SOME BURSTS OF HEAVIER SNOW TO WESTERN LOWER FOR A TIME THIS MORNING AS THOSE CONVECTIVE ELEMENTS HEAD INLAND. BIGGER QUESTION IS WHAT TO DO WITH THE BAND OVER NORTHERN LAKE MICHIGAN? INDICATIONS ARE THAT CONVERGENCE WILL WEAKEN THIS MORNING AS LOW LEVEL FLOW FORECAST TO BECOME MORE UNIFORMLY SOUTHWEST. BUT DOES APPEAR THAT THERE COULD BE A SEVERAL HOUR WINDOW THIS MORNING WITH HEAVY SNOWFALL RATES ACROSS PARTS OF CHARLEVOIX/EMMET/EXTREME NORTHERN CHEBOYGAN/ SOUTHEASTERN MACKINAC COUNTIES. EVEN AS THE MAIN BAND MOVES INLAND AND WEAKENS...SOUTHWEST FLOW LES PARAMETERS ARE NOT BAD EVEN WITH MARGINALLY WARM (AROUND -11C) 850MB TEMPERATURES. LAPSE RATES ARE AT OR GREATER THAN MOIST ADIABATIC THROUGH 500MB...WITH FORECAST LAKE INDUCED CAPES A DECENT 400-450 J/KG THROUGH MIDDAY BEFORE DROPPING DURING THE AFTERNOON AS 850MB TEMPERATURES CONTINUE TO WARM AND INVERSION BECOMES A BIT BETTER DEFINED WITH WEAK DOWNWARD FORCING. GIVEN THIS THINKING...WENT AHEAD EARLIER AND PUT UP AN LES ADVISORY FOR THE ABOVE LISTED COUNTIES THROUGH THE AFTERNOON HOURS. RAN WITH ACCUMULATIONS OF 3-7 INCHES FROM NOW THROUGH LATE AFTERNOON. WANTED TO GET SOMETHING OUT BEFORE THE HEAVIER SNOWFALL RATES MOVED IN (WHICH WOULD HAVE OCCURRED PRIOR TO SCHEDULED FORECAST ISSUANCE). JUST ANOTHER NORTHERN MICHIGAN SNOW "FLASH FLOOD" EVENT... FOR TONIGHT...ATTENTION WILL BE FOCUSED ON SHORT WAVE COMING OUT OF NE AS IT TRACKS ACROSS THE OHIO VALLEY. GUIDANCE TREND HAS BEEN A BIT FARTHER SOUTH WITH TIME...WITH A SURFACE LOW TRACK NOW ACROSS IN/OH/LAKE ERIE. GIVEN THE PENCHANT FOR SYSTEMS TO END UP TRACKING FARTHER NORTH SO FAR THIS COLD SEASON...MIGHT END UP LOOKING FOOLISH TO SAY THAT THERE IS REASONABLE CONFIDENCE THAT THIS SYSTEM WILL REMAIN FAR ENOUGH SOUTH TO OFFER JUST A GLANCING BLOW TO CENTRAL LOWER MI COUNTIES. BUT THERE...I JUST WROTE IT. AT THE VERY LEAST...THE TREND HAS BEEN AWAY FROM US...UNLIKE IN PRIOR SYSTEMS WHERE THE TREND WAS FARTHER NORTH WITH TIME. GIVEN THE CURRENT TRACK OF THE WAVE...UNLESS SOMETHING FUNKY HAPPENS ALOFT...THE NORTHERN OHIO VALLEY ROUTE LOOKS PRETTY GOOD. SOME QG FORCING SPREADS INTO NORTHERN LOWER...BUT PROVIDED MID LEVEL DEFORMATION ZONE SETS UP ACROSS SOUTHERN LOWER AS FORECAST...THEN THE MAJORITY OF THE ACTION WILL STAY OUT OF THE FORECAST AREA. WILL CARRY HIGHEST POPS EAST OF AN APN-HTL LINE...CLOSEST TO PASSING SYSTEM TO THE SOUTH AND ACKNOWLEDGING POTENTIAL FOR SOME SHALLOW LAKE HURON LES TO GET GOING OVERNIGHT AS WINDS TAKE ON AN EASTERLY COMPONENT. NEW YEAR`S DAY TUESDAY...AS SURFACE LOW PULLS AWAY FROM LAKE ERIE... TROUGH AXIS WILL BE HANGING BACK ACROSS LOWER MI...EVENTUALLY TURNING INTO THE LEADING EDGE OF THE COLD AIR DROPPING IN FROM ONTARIO. LINGERING DEEP MOISTURE AND CONTINUED STEEP LAPSE RATES THROUGH THE COLUMN WILL KEEP THE THREAT FOR SNOW GOING ACROSS THE FORECAST AREA. BUT THE BIGGER PROBLEM MAY BE THE LAKE ENHANCEMENT... AND AM BECOMING INCREASINGLY CONCERNED ON THE LAKE MICHIGAN SIDE. ALTHOUGH 850MB TEMPERATURES ARE SOMEWHAT MARGINAL (STILL AROUND -11C)...STEEP LAPSE RATES YIELD NO REAL INVERSION (FORECAST LAKE INDUCED CAPES CLIMBING INTO THE 400-500 J/KG RANGE DURING THE AFTERNOON)...DEEP LAYER MOISTURE PERSISTING...AND A FAIRLY CONSISTENT WIND DIRECTION THROUGH MUCH OF THE DAY (340 DEGREES OR SO) TARGETS AREAS ALONG/WEST OF US-131 FOR DECENT SNOWFALL. INVERTED TROUGH AXIS A COMPLICATING FACTOR...THOUGH NOT FORECAST TO SWEEP INTO CENTRAL LAKE MICHIGAN UNTIL LATE IN THE DAY. COULD END UP WITH AN AREA OF CONVECTION THAT DEVELOPS ALONG THE TROUGH AND ENHANCES SNOWFALL POTENTIAL. AS FOR SNOW AMOUNTS...WILL START WITH HIGH END ADVISORY CRITERIA (4-6 INCHES) BUT AM CONCERNED ENOUGH THAT BELIEVE A LAKE EFFECT SNOW WATCH IS WARRANTED FOR TUESDAY INTO TUESDAY NIGHT FOR COUNTIES ALONG/WEST OF M-37. IF IT ENDS UP TRANSITIONING TO AN ADVISORY THAT IS FINE. INTERESTINGLY ONCE THE COLDER AIR ARRIVES TUESDAY NIGHT...INVERSION HEIGHTS BEGIN TO TANK AND WINDS WILL PROBABLY BE SOMEWHAT VARIABLE FROM NORTHEAST TO NORTH FOR A TIME. ALSO PLAN ON CARRYING SOME LIGHTER ACCUMULATIONS ON THE LAKE HURON SIDE WITH NORTH- NORTHEAST LOW LEVEL FLOW ON BACKSIDE OF SURFACE TROUGH. MARINE ISSUES...NO HEADLINES THROUGH TONIGHT. WILL NEED TO CONSIDER SMALL CRAFT ADVISORIES AT LEAST AROUND THE NORTHERN LOWER NEARSHORE ZONES ON TUESDAY. EARLY EXTENDED PERIOD (WEDNESDAY THROUGH FRIDAY)...NORTH-NORTHWEST FLOW LAKE EFFECT WILL CONTINUE TO BE AN ISSUE INTO WEDNESDAY... BEFORE DEEP LAYER RIDGING/STRONG HEIGHT RISES ALOFT PUSH INTO THE UPPER MIDWEST/GREAT LAKES ON THURSDAY. THIS WILL SHUT THE LAKE EFFECT OFF AS WARMER AIR FLOODS NORTHWARD. EXTENDED GUIDANCE STILL LOOKS DRY FOR THURSDAY/FRIDAY EVEN AS WARM ADVECTION COMMENCES. THURSDAY TEMPERATURES EXPECTED TO BE SEASONABLY COLD...BEFORE A NOTICEABLE WARM UP STARTS FRIDAY. NO CHANGES NECESSARY TO EXTENDED GRIDS (AS IF THE ABOVE ISSUES WEREN`T ENOUGH ALREADY). JPB && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ015>017-019. LAKE EFFECT SNOW WATCH FROM LATE TONIGHT THROUGH LATE TUESDAY NIGHT FOR MIZ020-025-026-031-032. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1048 AM EST MON DEC 31 2007 .SYNOPSIS... LOW PRESSURE WILL SWING OUT OF THE PLAINS AND ACROSS THE OHIO VALLEY TONIGHT...BRINGING AN AREA OF RAIN AND SNOW TO THE REGION. AS THE LOW MOVES EAST IT WILL USHER IN MUCH COLDER AIR AND SNOW SHOWERS FOR THE NEW YEAR. THE CHANCE FOR SNOW SHOWERS WILL CONTINUE THROUGH WEDNESDAY IN THE COLD NORTHWEST FLOW BEHIND THE FRONT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LIFR ST DECK AND FZFG CONTINUE TO STUBBORNLY HOLD ON ACRS PORTIONS OF CNTRL OH THIS MRNG. BACK EDGE IS SLOWLY MIXING OUT AND EXPECT MOST OF NE FCST AREA WILL BEGIN TO SEE SUNSHINE WITHIN THE NEXT HOUR OR SO. ELSEWHERE SKIES WERE MSTLY SUNNY. MANY OF THE SLICK SPOTS COURTESY OF THE PATCHY BLACK ICE THAT FORMED THIS MRNG IS GONE AS TEMPS HAD RISEN ABV 32F IN MANY LOCATIONS. MAKING SOME MINOR UPDATES FOR THE AFTN AS MID LVL DECK IS ALREADY QUICKLY APPCHG FROM THE WEST. EXPECT THESE CLOUDS WILL RAPIDLY OVERSPREAD FCST AREA DURING THE AFTN WITH SKIES BECMG MSTLY CLDY IN MUCH OF THE FCST AREA BY LATE AFTN. TRIMMED PCPN ONSET BACK ANOTHER HOUR OR TWO DURING THE ERLY EVNG AS 12Z NAM CONTINUES TO SLOW SFC LO PROGRESSION. ALSO DROPPED TEMPS BACK A DEG OR TWO AS CLOUDS FILTER IN. 12Z NAM CONTINUES TO TREND DEEPER AND FURTHER SOUTH WITH SFC LO TRACK TONIGHT. 00Z OP GFS/ECMWF HAVE BEEN FURTHER NORTH AND WEST AND WEAKER WITH SFC LO...AND 12Z RUC APPEARS TO BE MUCH CLOSER TO THIS SOLN. WILL BE INTERESTING TO SEE WHAT THE 12Z GFS/ECMWF RUNS SHOW. CURRENT SFC ANALYSIS INDCG SFC LO DOES APPEAR TO BE TRACKING FURTHER SOUTH THRU WRN MISSOURI...AND IT SHOULD BE NOTED THAT THE SFC LO IS CURRENTLY ABOUT 3-4MB DEEPER THAN MOST OF THE MODEL GUIDANCE. WILL MAINTAIN SNOW ADV HEADLINES FOR JUST WEST CNTRL OH ATTM...AND WILL EVALUATE ALL OF THE 12Z DATA AND CONTINUE TO MONITOR RADAR/OBS TO DETERMINE IF ANY ADJUSTMENTS IN THESE HEADLINES ARE NEEDED LATER THIS AFTN. ZONE AND GRID UPDATES WILL BE OUT SHORTLY. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... THE NAM AND NGM ARE A LITTLE FARTHER S THAN THE GFS/ECMWF AS THEY TRACK A BAND OF HEAVY PCPN ACROSS THE NW COUNTIES. THE GFS AND ECMWF ARE A LITTLE FARTHER N...JUST TO THE N OF AOH. PREFERRED THE GFS/ECMWF HANDLING OF THE SYSTEM. THICKNESSES SHOULD BE WARM ENUF FOR THE PCPN TO START AS RAIN...THEN CHANGE TO SNOW. NW COUNTIES SHOULD SEE A BAND OF 1-3 INCHES OF SNOW...WITH GENERALLY LESS THAN AN INCH ELSEWHERE. SN SHOULD BEGIN TO TRANSITION TO SHSN FROM SW TO NE BETWEEN 06Z- 12Z TUE. BEHIND THE LOW...THE FLOW OFF LAKE MICHIGAN WILL BE FAVORABLE FOR SNOW SHOWERS TUESDAY INTO TUESDAY NIGHT. KEPT HIGH CHANCE POPS...AND SOME LOCATIONS MAY RECEIVE ANOTHER INCH OR TWO ACCUMULATION THROUGH THAT PERIOD. CAA NW FLOW ACROSS OPEN LAKES CONTINUES INTO WED. SHSN SHOULD BE A LITTLE MORE SCT ON WED. TEMPERATURES WILL FALL FROM ABOVE NORMAL ON MONDAY TO BELOW NORMAL. WENT CLOSE TO MAV GUIDANCE WHICH LOOKS REASONABLE IN THIS PATTERN. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... NW FLOW LINGERS INTO WED NGT...SO KEPT A MENTION OF A SHSN IN THE EVENING. HIGH PRESSURE THEN BUILDS IN LATE WED NIGHT AND WILL CONTROL THE WEATHER FOR THURSDAY AND FRIDAY. SLY FLOW ON BACKSIDE OF HIGH PULLS MOISTURE N FROM THE GULF FROM FRI. BACKED OFF ON THE ONSET OF THE PCPN FRI DAY. LITTLE CHANGE TO THE FORECAST FOR SAT NGT INTO SUNDAY. NEW MOS GUIDANCE WAS COOLER. IN THIS PATTERN IT LOOKED APPROPRIATE. && .AVIATION /16Z MONDAY THROUGH FRIDAY/... WITH AN EXCEPTION OF A FINGER OF LOW STRATUS DEVELOPING FROM WASHINGTON COURT HOUSE TO COLUMBUS...SKIES ARE RELATIVELY CLEAR OVER THE FORECAST AREA WITH PATCHY FREEZING FOG...MORESO IN THE LOWER RIVER VALLEYS. THESE CONDITIONS SHOULD CLEAR UP WITH THE DAWNING DAY AND INCREASED PRESSURE GRADIENT AND SOUTH SOUTHWEST WINDS. STRONG LOW PRESSURE WILL SEE MID CLOUDS STREAM INTO OHVLY AHEAD OF IT THIS AFTERNOON. THE LOW IS NOTED TO BE WITHIN 20 MILES OR SO FROM WAPAKONETA BY 6Z TOMORROW NIGHT. PRECIP SHOULD STAY LIQUID THROUGH ABOUT 4-5Z IN CVG/LUK/ILN...AN HOUR OR THREE LATER AT CMH/LCK. DAYTON MAY ONLY SEE AN HOUR OR TWO OF RAINFALL AT THE ONSET OF THE PRECIPITATION AND THEN QUICKLY TURN TO ALL SNOW. MAIN DIFFICULTY WITH TAFS IS HAVING 3-5SM VSBYS IN SNOW WITH A 18-20KT SUSTAINED WEST WIND. CIGS SHOULD BE BTWN 1-2KFT FOR MOST OF THE TAF SITES AS THE COLD AIR RUSHES IN ON THE BACK SIDE OF THIS QUICKLY EXITING SYSTEM. OUTLOOK...MVFR/IFR CIGS/VSBYS POSSIBLE THROUGH WEDNESDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...SNOW ADVISORY FROM 9 PM THIS EVENING TO 6 AM EST TUESDAY FOR OHZ026-034-035-043-044. KY...NONE. IN...NONE. && $$ SYNOPSIS...SITES NEAR TERM...RYAN SHORT TERM...SITES LONG TERM...SITES AVIATION...FRANKS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 235 PM EST MON DEC 31 2007 ...STRONG ARCTIC COLD FRONT WILL LIKELY BRING FREEZING TEMPERATURES TO THE REGION FOR THE MID-WEEK PERIOD... ...LONG DURATION OF SMALL CRAFT ADVISORY CONDITIONS EXPECTED WITH POSSIBLE GALE FORCE GUSTS TUESDAY THROUGH WEDNESDAY NIGHT... .SYNOPSIS... 19Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING MUCH OF NORTH AMERICA STILL DOMINATED BY LONG WAVE TROUGHING. SOUTHERN STREAM MOISTURE HAS BEEN PUSHED EAST AND NOW IS STREAMING NORTHWARD FROM THE SE GULF OF MEXICO INTO THE WESTERN ATLANTIC. STRONG SHORTWAVE EMBEDDED WITHIN THE LARGER SCALE TROUGH IS BEGINNING TO DIG SOUTH AND EAST ACROSS THE CENTRAL PLAINS/MIDDLE MISSISSIPPI VALLEY. SECONDARY PIECE OF SHORTWAVE ENERGY IS PUSHING RAPIDLY SOUTH INTO THE NORTHERN PLAINS AND WILL JOIN FORCES WITH THE FIRST SHORTWAVE OVER THE NEXT 24 HOURS TO CARVE OUT A LARGER AND MUCH MORE AMPLIFIED MID/UPPER LEVEL TROUGH OVER THE EASTERN HALF OF THE NATION. AT THE SURFACE...WEAK HIGH PRESSURE REMAINS IN CONTROL OF THE FORECAST AREA INTO THE EVENING HOURS. MOSTLY SUNNY SKIES ARE FOUND NORTH AND WEST OF A LINE FROM KPFN TO KTLH AND KVLD. FURTHER SOUTH AND EAST CLOUDS ARE A BIT MORE WIDESPREAD ASSOCIATED WITH A REGION OF ISENTROPIC UPGLIDE ALONG THE 295-300K SURFACES. A FEW VERY LIGHT SHOWERS CAN ALSO NOT BE RULED OUT DURING THE EVENING HOURS SOUTH AND EAST OF A LINE FROM KAAF TO KTLH AND KVLD...ALTHOUGH ANY RAINFALL (IF ANY) SHOULD BE LIGHT AND SHOULD HAVE ONLY MINOR IMPACTS ON OUTDOOR PLANS. && .SHORT TERM...TONIGHT THROUGH THURSDAY MORNING. FORECAST ATTENTION HAS SHIFTED TO THE APPROACH OF A STRONG ARCTIC COLD FRONT ARRIVING AFTER MIDNIGHT FROM THE NORTHWEST. LATEST GFS/NAM GUIDANCE BRINGS THE FRONT TO AROUND KDHN AND KABY BETWEEN 07-09Z AND THEN EXITS THE FRONT SOUTH OF THE COASTAL WATERS AND KCTY BY 14Z TUESDAY MORNING. ALTHOUGH HIGHS WILL STILL BE IN THE 50S ON TUESDAY UNDER PARTLY TO MOSTLY SUNNY SKIES WITH THE COLDEST AIR NOT ARRIVING UNTIL TUESDAY NIGHT...GUSTY NORTHWEST WINDS WILL MAKE IT FEEL COOLER. A DEEP TROUGH WILL HAVE CARVED OUT ACROSS THE EASTERN U.S BY SUNDOWN TUESDAY WITH THE TROUGH AXIS RUNNING THROUGH OUR FORECAST AREA. LATEST GFS/ECMWF GUIDANCE IS SHOWING 850MB TEMPS DROPPING TO BETWEEN -7 AND -12C FROM SOUTH TO NORTH BY SUNRISE WEDNESDAY MORNING. 12Z NAM IS ACTUALLY A COUPLE OF DEGREES COOLER BUT IS AN OUTLIER FROM THE GLOBAL MODELS AT THIS TIME. EITHER WAY...THIS IS A FAIRLY IMPRESSIVE COLD AIRMASS FOR OUR AREA. LOOKING AT IT STATISTICALLY...THESE 850MB TEMPS ARE AROUND -4.0 STANDARD DEVIATIONS FROM CLIMATOLOGY. TO PUT THIS IN PLAIN WORDING...A 4.0 STANDARD DEVIATION EVENT HAS A LESS THAN A ONE HALF PERCENT (< 0.5%) PROBABILITY OF OCCURRENCE. SO...ALTHOUGH WE HAVE CERTAINLY SEEN COLDER AIRMASS IN THE PAST...THIS IS STILL A VERY RARE OCCURRENCE. LOOKING FOR A WIDESPREAD ADVECTION FREEZE TUESDAY NIGHT INTO WEDNESDAY MORNING WITH MANY AREAS APPROACHING HARD FREEZE CRITERIA. FORECAST LOW TEMPS WILL BE BETWEEN 22 AND 28F DEGREES ALMOST REGIONWIDE WITH NORTHERLY FLOW BRINGING THE VERY COLD AIR BASICALLY TO THE BEACHES. ALSO WITH THE SURFACE HIGH WELL TO THE WEST RESULTING IN NORTHERLY FLOW PREVAILING THROUGH THE NIGHT...WIND CHILL VALUES ARE LIKELY TO FALL INTO THE TEENS OVER A LARGE AREA. WITH TEMPS APPROACHING HARD FREEZE CRITERIA COMBINED WITH THE EXPECTED EXTENDED DURATION OF TEMPS BELOW FREEZING WILL LIKELY HAVE A SIGNIFICANT IMPACT AND WILL ISSUE A HARD FREEZE WATCH FOR ALL ZONES LATE TUESDAY NIGHT UNTIL LATE WEDNESDAY MORNING. REFER TO OUR HARD FREEZE WATCH PRODUCT (MIANPWTAE) TO BE ISSUED DURING THE LATE AFTERNOON...OR YOUR FAVORITE MEDIA OUTLET FOR FURTHER INFORMATION ON THE IMPENDING FREEZE. SURFACE RIDGE BEGINS TO SHIFT EASTWARD INTO THE LOWER AND MIDDLE MISSISSIPPI VALLEY ON WEDNESDAY WITH THE UPPER TROUGH BEGINNING TO PUSH OFF THE EAST COAST. WITH THE LOW LEVEL ATMOSPHERIC COLUMN AS COLD AS EXPECTED ON WEDNESDAY...HIGH TEMPS ARE LIKELY TO ONLY RISE INTO THE LOWER 40S NORTH AND MIDDLE TO UPPER 40S SOUTH. THIS WILL BE DESPITE PARTLY TO MOSTLY SUNNY SKIES AND A DECENT GRADIENT FOR DAYTIME MIXING. IF FACT...WITH 850MB TEMPS STILL BETWEEN -10 AND -11C DURING THE AFTERNOON OVER SE AL/SW GA...EVEN THESE NUMBERS MAY BE A BIT OPTIMISTIC AND WOULD NOT BE SURPRISED TO SEE A STATION OR TWO ACROSS OUR NORTHERN AREAS OF SE AL AND SOUTHWEST GEORGIA STRUGGLE TO 40F. SURFACE RIDGE MOVES TO THE TENNESSEE VALLEY BY LATE WEDNESDAY NIGHT. ALTHOUGH THIS IS NOT A PERFECT POSITION...DO BELIEVE THE HIGH CENTER WILL BE CLOSE ENOUGH AND THE GRADIENT RELAXED ENOUGH TO ALLOW DECOUPLING. THE LOW LEVEL ATMOSPHERE WILL BE EXTREMELY DRY WEDNESDAY AFTERNOON INTO THURSDAY MORNING AND WHEN COMBINED WITH THE LIGHTER WINDS AND GENERALLY CLEAR SKIES...SHOULD RESULT IN GOOD RADIATIONAL COOLING CONDITIONS. ANOTHER WIDESPREAD HARD FREEZE IS BECOMING LIKELY FOR ALL AREAS AWAY FROM THE IMMEDIATE COAST. AS WITH MOST RADIATIONAL COOLING SCENARIOS...THE SHORELINE IS LIKELY TO BE A FEW DEGREES WARMER...BUT EVEN HERE THIS WILL BORDER ON HARD FREEZE CRITERIA AND CERTAINLY SHOULD BE LOOKING AT SUB-FREEZING TEMPS DOWN TO THE WATERS EDGE. LOW TEMPS ARE ANTICIPATED TO FALL TO BETWEEN 20 AND 25 DEGREES INLAND AND 25 TO 30 DEGREES AT THE SHORELINE. A FEW NORMALLY COLDER LOCATIONS MAY EVEN EXPERIENCE UPPER TEENS. MAV GUIDANCE NUMBERS ARE ACTUALLY A FEW DEGREES COOLER THAN THESE FORECAST NUMBERS...HOWEVER THE MAV HAS HAD A COOL BIAS THIS WINTER SEASON...ESPECIALLY WITH RADIATIONAL COOLING EVENTS. WHAT SHOULD BE UNDERSTOOD IS THAT AN EXTENDED PERIOD 10+ HOURS OF SUB-FREEZING TEMPS ARE POSSIBLE FOR MANY AREAS WEDNESDAY EVENING INTO THURSDAY MORNING. THIS WILL LIKELY HAVE SIGNIFICANT IMPACTS AROUND THE REGION. ONCE AGAIN REFER TO OUR HARD FREEZE WATCH PRODUCT (MIANPWTAE) FOR FURTHER INFORMATION. && .LONG TERM...THU THROUGH MON. THE ABOVE MENTIONED ARCTIC RIDGE WILL DOMINATE THE BEGINNING OF THE EXTENDED PERIOD AS THE SHARP UPPER LEVEL TROF REMAINS CARVED OUT OVER THE SE EARLY THURSDAY. THEREAFTER...LOW AMPLITUDE UPPER LEVEL RIDGING WILL STRETCH EASTWARD FROM TX TO FL AS THE ARCTIC HIGH EVENTUALLY MOVES OFF THE MID ATLANTIC COAST BY SATURDAY. THIS WILL ALLOW RETURN FLOW TO SET UP OVER THE REGION WITH GRADUALLY MODERATING TEMPERATURES. ALTHOUGH TEMPS WILL MODERATE... LOW LEVEL MOISTURE WILL BE EVEN SLOWER TO RETURN...WITH THE NEXT REASONABLE CHANCE FOR RAIN NOT EXPECTED UNTIL MID WEEK OF NEXT WEEK. && .MARINE... NORTHEAST FLOW OVER THE FORECAST WATERS AROUND 10 KNOTS WILL CONTINUE INTO THIS EVENING. FLOW WILL COME AROUND LATE THIS EVENING TO THE WEST AND NORTHWEST BETWEEN 10 AND 15 KNOTS IN ADVANCE OF A STRONG ARCTIC COLD FRONT. THIS FRONT PUSHES THROUGH THE WATERS EARLY TUESDAY MORNING WITH WIND AND SEAS RAPIDLY BUILDING TO ADVISORY LEVELS FOR ALL LEGS. AS STRONG HIGH PRESSURE BUILDS DOWN INTO THE SOUTHERN PLAINS TO OUR WEST THE COMBINATION OF A TIGHT PRESSURE GRADIENT AND STRONG COLD AIR ADVECTION WILL INCREASE WINDS EVEN FURTHER TUESDAY EVENING AND OVERNIGHT WITH SUSTAINED FLOW BETWEEN 25 AND 30 KNOTS POSSIBLE OVER A LARGE AREA. IT IS VERY POSSIBLE THAT GUSTS...OR EVEN FREQUENT GUST TO GALE FORCE WILL OCCUR TUESDAY NIGHT INTO WEDNESDAY MORNING. ADVISORY LEVEL WINDS AND SEAS WILL CONTINUE INTO WEDNESDAY NIGHT BEFORE SUBSIDING TO THE CAUTIONARY RANGE DURING THURSDAY AS HIGH PRESSURE SLIDES TO OUR NORTH. && .AVIATION... KTLH AND KVLD WILL BE ALONG THE NORTHERN FRINGES OF A FRONTAL CLOUD BAND. A FEW LIGHT SHOWERS AND OCCASIONAL MVFR CIGS WILL OCCUR WITHIN THIS CLOUD BAND THIS AFTERNOON AND EVENING...BUT THE MOST LIKELY SCENARIO IS FOR PREVAILING VFR CONDITIONS AT ALL TERMINALS THROUGH TUESDAY. AN ARCTIC COLD FRONT WILL MOVE THROUGH THE REGION TUESDAY MORNING BUT NO RAIN OR SIGNIFICANT CLOUD COVER IS EXPECTED WITH THIS SYSTEM. HOWEVER...NW SURFACE WINDS OF 10-15KT WITH GUSTS TO 25KT ARE EXPECTED BY MID TO LATE TUESDAY MORNING AND INTO THE AFTERNOON BEHIND THE FRONT. && .FIRE WEATHER... STRONG ARCTIC COLD FRONT WILL CROSS THE AREA EARLY TUESDAY USHERING IN A MUCH COLDER AND DRIER AIRMASS TO THE REGION. THE DRIEST AIR WILL NOT BEGIN TO ARRIVE UNTIL TUESDAY EVENING KEEPING ALABAMA AND GEORGIA ABOVE CRITICAL LEVELS OF RH ON TUESDAY. HOWEVER OUR FLORIDA ZONES ARE EXPECTED TO SEE BETWEEN 2 AND 3 HOURS OF RH AT OR BELOW 35 PERCENT COMBINED WITH GUSTY NORTHWEST WINDS OF 15+MPH AND HIGH DISPERSION INDICES. THEREFORE...THE RED FLAG WARNING WILL BE CONTINUED FOR TUESDAY AFTERNOON. DESPITE HIGH TEMPS ON WEDNESDAY ONLY REACHING THE LOWER AND MIDDLE 40S...VERY DRY AIR WILL HAVE ARRIVED RESULTING IN ANTICIPATED LONG DURATIONS OF RH BELOW CRITICAL LEVELS FOR ALL AREAS...THEREFORE A FIRE WX WATCH IS NOW IN EFFECT WEDNESDAY FOR ALL OF SE AL...SW AND SOUTH-CENTRAL GA...THE EASTERN FL PANHANDLE AND FL BIG BEND. FIRE WX CONCERNS ARE LIKELY TO CONTINUE FOR ALL AREAS INTO THURSDAY. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 43 58 25 45 21 / 15 0 0 0 0 PANAMA CITY 46 56 28 47 26 / 10 0 0 0 0 DOTHAN 39 53 25 42 22 / 0 0 0 0 0 ALBANY 40 55 25 42 21 / 10 0 0 0 0 VALDOSTA 42 58 25 44 22 / 15 0 0 0 0 CROSS CITY 47 64 25 48 19 / 20 05 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...HARD FREEZE WATCH FROM 1100 PM CST TUESDAY NIGHT THROUGH 1000 AM CST WEDNESDAY MORNING FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: COFFEE...DALE...GENEVA...HENRY...HOUSTON. GA...HARD FREEZE WATCH FROM 1200 AM EST/1100 PM CST TUESDAY NIGHT THROUGH 1100 AM EST/1000 AM CST WEDNESDAY MORNING FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS... CALHOUN...CLAY...COLQUITT...COOK...DECATUR...DOUGHERTY... EARLY...GRADY...IRWIN...LANIER...LEE...LOWNDES...MILLER... MITCHELL...QUITMAN...RANDOLPH...SEMINOLE...TERRELL... THOMAS...TIFT...TURNER...WORTH. FIRE WEATHER WATCH WEDNESDAY AFTERNOON FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN...CLAY... COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY...GRADY... IRWIN...LANIER...LEE...LOWNDES...MILLER...MITCHELL... QUITMAN...RANDOLPH...SEMINOLE...TERRELL...THOMAS...TIFT... TURNER...WORTH. FL...RED FLAG WARNING FROM 12 PM EST /11 AM CST/ TO 7 PM EST /6 PM CST/ TUESDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN... DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. HARD FREEZE WATCH FROM 1200 AM EST/1100 PM CST TUESDAY NIGHT THROUGH 1100 AM EST/1000 AM CST WEDNESDAY MORNING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN... GADSDEN...GULF...HOLMES...INLAND WALTON..JACKSON... JEFFERSON...LAFAYETTE...LEON...LIBERTY..MADISON...TAYLOR... WAKULLA...WASHINGTON. FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE... FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON... JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...SMALL CRAFT ADVISORY NOW IN EFFECT FOR ALL COASTAL LEGS FROM 7 AM EST/6 AM CST TUESDAY MORNING THROUGH 7 AM EST/6 AM CST THURSDAY MORNING. && $$ AVIATION...FOURNIER PUBLIC/MARINE/FIRE WX...MROCZKA LONG TERM...DUVAL/GOULD fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1223 PM CST MON DEC 31 2007 .DISCUSSION... ISSUED 1155 AM CST MON DEC 31 2007 UPDATE THE FORECAST TO EXPAND THE SNOW ADVISORY A TIER OF COUNTIES SOUTH THIS AFTERNOON AND EVENING AND FOR EAST CENTRAL IL FROM 3 PM TO MIDNIGHT. ALSO INCREASED SNOW FALL AMOUNTS TO BETWEEN 2 AND 4 INCHES WITH LOCALLY HIGHER AMOUNTS ALONG I-74 THIS AFTERNOON AND EVENING. THANKS FOR THE COORDINATION FROM SURROUNDING NWS OFFICES. WRF...GFS AND SHEF MODELS SHOW 2 TO 4 INCH SNOW AMOUNTS ACROSS MUCH OF CENTRAL IL THIS AFTERNOON AND EVENING...WITH LOCAL HIGHER AMOUNTS OF 4 TO 6 INCHES ALONG I-74. RUC MODEL UPDATE THROUGH 03Z SHOWS 1 TO 2 INCHES LESS SNOW AND MAINLY ALONG AND NORTH OF I-74. USED A BLEND OF THESE MODELS AND TRENDS WHICH HAVE BEEN GOING UP WITH SNOWFALL AMOUNTS OVER CENTRAL IL THIS AFTERNOON/EVENING. NOON SURFACE MAP SHOWS 1008 MB LOW PRESSURE OVER CENTRAL MO AND DEEPENING A BIT. A WARM FRONT EXTENDS EAST INTO CENTRAL IL SOUTH OF I-72 AND JUST NORTH OF CHARLESTON/MATTOON AND PARIS. LIGHT SNOW DEVELOP AT GALESBURG LATE THIS MORNING WITH VSBY DOWN TO 2 MILES. THIS DEVELOPING BAND OF LIGHT SNOW WAS OVER NW IL INTO SE IA AND NE MO AHEAD OF THIS LOW PRESSURE. TEMPS RANGED FROM THE UPPER 20S FROM PEORIA AND BLOOMINGTON NORTH TO THE LOWER 40S IN SE IL. ALOFT AN UPPER LEVEL TROF WAS OVER THE CENTRAL PLAINS WITH THE TROF AXIS ALONG THE IA/NE AND MO/KS BORDER. MODELS DEEPEN LOW PRESSURE A BIT MORE AS IT MOVES INTO SOUTHERN IL BY 00Z/6 PM AND DEEPENS MORE TO 1002 OVER NW OH BY MIDNIGHT AS UPPER LEVEL DYNAMICS STRENGHTHEN INTO THE STORM. THIS SYSTEM HAS MOISTURE TO WORK WITH AND LIFT FROM STRONG UPPER LEVEL JET AND DYNAMICS. AREAS FURTHER EAST OVER CENTRAL/NORTHERN INDIANA WILL LIKELY SEE MORE SNOW. FELT EAST CENTRAL IL TO HAVE HIGHER SNOW AMOUNTS IN THE ADVISORY CRITERIA LATE THIS AFTERNOON AND EVENING. SNOW TO DEVELOP FROM NW TO SE DURING THE AFTERNOON...THEN DIMINISH FROM THE WEST DURING THE EVENING...ESPECIALLY AFTER 03Z/9 PM. WARM ENOUGH FOR RAIN THIS AFTERNOON IN SE IL FROM I-70 SE WHERE HIGHS 40 TO 45. HAVE CHANCE OF LIGHT RAIN OR LIGHT SNOW SOUTH OF I-72 TO I-70 EARLY THIS AFTERNOON BEFORE IT CHANGES TO ALL SNOW LATE. GUSTY NW WINDS TO DEVELOP DURING THE EVENING AND CONTINUE THROUGH TUE TO CAUSE SOME BLOWING AND DRIFTING SNOW AND USHER IN MUCH COLD AIR FOR THE NEAR YEAR. HUETTL && .AVIATION... ISSUED 1215 PM CST MON DEC 31 2007 VFR CONDITIONS CURRENTLY OVER CENTRAL IL TAF SITES TO QUICKLY DETERIATE THIS AFTERNOON AS SNOW DEVELOPS FROM THE NW. SNOW BEGINS AT PIA BETWEEN 18Z-19Z...AT BMI BY 20Z...SPI BY 21Z...DEC 21-22Z AND CMI BETWEEN 22 AND 23Z. HAVE IFR VSBYS DEVELOPING THIS AFTERNOON WITH MVFR TO IFR CEILINGS. VLIFR TO LIFR VSBYS OF 1/4 TO 1/2 MILE AND LIFR CIELINGS AT OR BELOW 500 FT TO DEVELOP IN THE MODERATE TO HEAVY SNOW BANDS TO SET UP LATE THIS AFTERNOON AND EARLY EVENING RANGING FROM 22Z- 02Z AT PIA TO 00Z-04Z AT CMI. SNOW TO DIMINISH FROM THE WEST TO JUST FLURRIES AFTER 03Z WITH MVFR TO VFR VSBYS RETURNING. BUT IFR CIELINGS AROUND 1K FT OR LESS TO LINGER THROUGH 18Z/TUE. LIGHT SE WINDS EARLY THIS AFTERNOON TO BECOME NW AROUND 12Z LATER THIS AFTERNOON AND GUSTY 25 TO 32KTS TONIGHT AND TUE MORNING. THIS IN RESPONSE TO 1008 MB LOW PRESSURE IN CENTRAL MO THAT MOVES INTO SOUTHERN IL BY 00Z...THEN DEEPENS TO 1002 MB OVER NW OH BY 06Z AND TO 997 MB OVER LAKE ERIE TUE MORNING. HUETTL && .PREV DISCUSSION... ISSUED 202 AM CST MON DEC 31 2007 SEVERAL CONCERNS WITH THIS FORECAST PACKAGE...PRIMARILY IN THE SHORT-TERM. FIRST ISSUE WILL BE SNOW CHANCES THIS AFTERNOON AND EVENING...THEN MAIN CONCERN WILL BE THE WINDY AND COLDER CONDITIONS SETTLING INTO THE REGION FOR TUESDAY AND WEDNESDAY. LATEST SURFACE ANALYSIS SHOWS LOW PRESSURE BEGINNING TO GET ORGANIZED ACROSS SOUTHERN KANSAS...IN RESPONSE TO 140KT 300MB JET STREAK TRACKING THROUGH THE CENTRAL ROCKIES. PLENTY OF LOW AND MID-LEVEL CLOUDS ASSOCIATED WITH THIS DEVELOPING SYSTEM...HOWEVER LITTLE IN THE WAY OF PRECIP JUST YET. SHORT TERM...TODAY THROUGH WEDNESDAY 00Z 31 DEC MODELS HAVE MADE AN ABRUPT SHIFT SOUTHWARD WITH THE APPROACHING SYSTEM FOR LATER TODAY...NOW KEYING IN ON THE UPPER WAVE TRACKING ACROSS THE CENTRAL PLAINS RATHER THAN THE ONE FURTHER NORTH CLOSER TO THE CANADIAN BORDER. END RESULT...IS A STRONGER AND MUCH FURTHER SOUTH SURFACE LOW. BOTH NAM-WRF/GFS ARE IN GOOD AGREEMENT WITH THE TRACK OF THIS LOW...HOWEVER THE NAM-WRF IS A TAD FURTHER SOUTH. BASED ON LATEST ANALYSIS...IT APPEARS NAM-WRF IS VERIFYING BETTER THAN THE GFS...SO WILL TREND TOWARD ITS SOLUTION MOST CLOSELY. LOW PRESSURE CURRENTLY OVER KANSAS WILL TRACK E/NE TO SAINT LOUIS BY 18Z...THEN TO NEAR TERRE HAUTE BY 00Z TUE. THIS PARTICULAR TRACK WOULD BRING THE BEST CHANCE FOR ACCUMULATING SNOW TO THE NORTHERN TWO-THIRDS OF THE KILX CWA...MAINLY ALONG AND NORTH OF I-72. FURTHER SOUTH...PRECIP WILL BE MUCH LIGHTER AND MUCH MORE SCATTERED IN NATURE. HAVE ADJUSTED POPS ACCORDINGLY...WITH CATEGORICAL NORTH OF I-72 TAPERING DOWN TO JUST SLIGHT CHANCE SOUTH OF I-70. MID AND LOW-LEVELS OF THE ATMOSPHERE WILL INITIALLY BE RATHER DRY...SO ONSET OF PRECIP WILL LIKELY BE DELAYED UNTIL AFTERNOON IN MOST LOCATIONS. BASED ON NAM-WRF FORECAST SOUNDINGS...SNOW SHOULD BEGIN AT KPIA BETWEEN 18Z AND 21Z...THEN FURTHER EAST AND SOUTH AT BOTH KSPI AND KCMI BETWEEN 21Z AND 00Z. STRONG FRONTOGENETIC FORCING AND FAVORABLE UPPER DYNAMICS WILL LEAD TO A PERIOD OF MODERATE SNOW THIS AFTERNOON AND EVENING. DESPITE THESE FAVORABLE PARAMETERS...TOTAL DURATION OF SNOWFALL WILL ONLY BE BETWEEN 4 AND 6 HOURS...WHICH WILL TEND TO LIMIT ACCUMULATIONS. THINK NAM-WRF QPF FIELD IS OVERDONE...SO WILL TRIM VALUES BACK A BIT...RESULTING IN A SWATH OF ONE TO THREE INCH SNOWFALL ALONG AND NORTH OF I-72. BASED ON EXPECTED TRACK OF THE 850MB LOW...HEAVIEST SNOW OF BETWEEN 2 AND 3 INCHES WILL LIKELY OCCUR ALONG AND NORTH OF A RUSHVILLE TO BLOOMINGTON LINE. FURTHER SOUTH...LITTLE OR NO SNOW WILL FALL ALONG AND SOUTH OF I-70 UNTIL LATER THIS EVENING WHEN MOISTURE WRAPS AROUND THE DEPARTING LOW PRESSURE. ONCE LOW TRACKS INTO INDIANA...INCREASING NORTHWESTERLY WINDS WILL TRANSPORT MUCH COLDER AIR INTO CENTRAL ILLINOIS TONIGHT INTO TUESDAY. PRESSURE GRADIENT AND FORECAST SOUNDINGS SUPPORT WINDS IN THE 15 TO 25 MPH RANGE...WITH GUSTS AOA 35 MPH AT TIMES. THIS COULD CAUSE SOME PROBLEMS WITH BLOWING AND DRIFTING SNOW ACROSS THOSE AREAS THAT PICK UP AN INCH OR TWO TODAY. IN ADDITION...STRONGLY CYCLONIC FLOW ALOFT WILL AID IN THE DEVELOPMENT OF SCATTERED SNOW-SHOWERS THROUGH TUESDAY. WILL HAVE TO KEEP OUR EYES ON A RATHER VIGOROUS SHORT-WAVE DROPPING SOUTHWARD OUT OF CANADA AS WELL...AS IT HAS THE POTENTIAL TO BRING SOME ENHANCED SNOWFALL TO PARTS OF THE AREA. MODELS ARE NOT YET DEPICTING THIS IN THEIR RH OR QPF FIELDS...HOWEVER IT IS SHOWING UP IN FORCING FIELDS ALOFT. WITH STRONG CAA IN PLACE...TEMPS ON TUESDAY WILL STRUGGLE TO RISE FROM EARLY MORNING LOWS. HIGHS WILL RANGE FROM THE TEENS NORTHWEST...TO THE MIDDLE 20S FAR SOUTHEAST. VERY COLD CONDITIONS WILL BE ON TAP TUESDAY NIGHT...HOWEVER CLOUD COVER AND WIND SHOULD KEEP READINGS FROM COMPLETELY BOTTOMING OUT. EVEN STILL...LOWS WILL DIP INTO THE SINGLE DIGITS AND TEENS ACROSS THE BOARD. STRONG HIGH PRESSURE MOVES OVERHEAD ON WEDNESDAY...RESULTING IN CLEARING SKIES AND DIMINISHING WINDS. LONG TERM...THURSDAY THROUGH SUNDAY WARMING TREND BEGINS ON THURSDAY...AS SURFACE HIGH PRESSURE PUSHES OFF TO THE EAST AND UPPER FLOW BEGINS TO FLATTEN. WITH EXPECTED SNOW COVER...HAVE TEMPERED WARMING TREND SOMEWHAT...KEEPING TEMPS AT OR BELOW GUIDANCE THROUGH THURSDAY. AFTER THAT...MODELS CONTINUE TO ADVERTISE EVEN WARMER WEATHER FOR THE WEEKEND...WITH PERHAPS A CHANCE FOR PRECIP BEGINNING FRIDAY NIGHT. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ILZ027>031-036>038- 040>042-047-048. SNOW ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR ILZ043>046-055-057. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 248 PM MST MON DEC 31 2007 .DISCUSSION... 16Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED LONGWAVE TROUGH ACROSS MUCH OF THE CONUS...WITH RIDGING JUST OFF THE WEST COAST. 12Z RAOB DATA INDICATED A FEW 150KT JET STREAKS EMBEDDED IN THE FLOW AT H3 WITH ONE LOCATED ACROSS SOUTHERN COLORADO AND ANOTHER ALONG THE EAST COAST. STRONG GRADIENT AT H7 WAS NOTED WITH -15C OBSERVED AT KDDC AND -6C AT KLMN...WHICH LINED UP FAIRLY WELL WITH AREA OF CLOUDS THIS MORNING. AT THE SURFACE...COLD FRONT WAS WELL TO THE SOUTH OF THE CWA AND WAS LOCATED ACROSS CENTRAL TEXAS. OVERALL MODELS INITIALIZED WELL ACROSS THE AREA AND DIFFERENCES WITH LARGE SCALE FEATURES APPEAR MINIMAL BETWEEN THE OPERATIONAL MODELS AT THIS TIME. TONIGHT...FIRST CONCERN FOR THE PERIOD WILL BE POTENTIAL...IF ANY...FOR SNOW SHOWERS TO DEVELOP LATE THIS AFTERNOON INTO THE EVENING. KLBF SOUNDINGS SHOW FAIRLY STEEP LAPSE RATES OVER A GOOD DEPTH OF THE SOUNDING...WITH THETA-E LAPSE RATES BETWEEN H6 AND H5 AROUND 0. GFS SHIFTS THIS POCKET OF POTENTIAL INSTABILITY TO THE SOUTH ACROSS NORTHERN FRINGE OF COUNTIES. IT IS INTERESTING THAT LAPSE RATES ARE STEEP ENOUGH THAT WARMING THE SURFACE TO THE LOWER 30S WOULD BEGIN TO SUPPORT SFC BASED CONVECTION...ALTHOUGH IT WOULD BE VERY WEAK. ALTHOUGH STABILITY PROFILES LOOK FAVORABLE...FORCING APPEARS ABSENT AS SHORT WAVE TROUGH THAT IS CURRENTLY DROPPING THROUGH THE DAKOTAS WILL NOT BEGIN TO IMPACT THE AREA UNTIL AROUND 06Z AND MUCH OF THE FORCING FOR ASCENT WILL BE TO THE NORTH AND EAST. PLAN TO MONITOR TRENDS THIS AFTERNOON BEFORE MAKING ANY FINAL CALL ON PRECIP POTENTIAL. OTHER CONCERN FOR TONIGHT WILL BE WIND/TEMPS AND RESULTING WIND CHILLS. AS MENTIONED BEFORE...STABILITY AHEAD OF THE NEXT TROUGH IS FAIRLY LOW AND SHOULD SEE A DECENT SURFACE RESPONSE AS TROUGH APPROACHES. CONSENSUS OF RUC/NAM/GFS ALL KEEP WINDS UP THROUGH THE NIGHT AS PRESSURE GRADIENT TIGHTENS. WINDS STAYING UP ALL NIGHT MAY ALSO BE WHAT LIMITS WIND CHILL POTENTIAL AS WELL. WEST NORTHWESTERLY WINDS WILL KEEP LOWER BOUNDARY LAYER MIXED SOMEWHAT PREVENTING STRONG DECOUPLING. WIND DIRECTION WILL BE OFF THE SNOWPACK WHICH MAY OFFSET THINGS...BUT ALL IN ALL EXPECT A SIMILAR DIURNAL SWING TO LAST NIGHT. CURRENT MIN TEMP THOUGHTS SEE THE WESTERN HALF OF COLORADO COUNTIES GET TO -13 TO -17 WIND CHILLS...MAINLY ACROSS THE WESTERN HALF OF EASTERN COLORADO COUNTIES. ALTHOUGH THINGS ARE MARGINAL...THINK A SHORT WIND CHILL ADVISORY FOR THE MORNING IS IN ORDER. NEW YEARS DAY/EVENING...SHORT WAVE TROUGH WILL CONTINUE TO THE SOUTH AND EAST OF THE AREA DURING THE MORNING HOURS AS LARGE SCALE RIDGING AND SUBSIDENCE MOVES INTO THE AREA. MAIN CONCERN FOR THIS PERIOD WILL BE WINDS THROUGH THE EARLY AFTERNOON. CWA...ESPECIALLY EASTERN CWA WILL HAVE STRONG HEIGHT/TEMP GRADIENT BETWEEN BUILDING RIDGE AND DEPARTING TROUGH...RESULTING IN AN AXIS STRONG WINDS ALOFT ACROSS THE AREA. MODELS DIFFER IN THE ACTUAL STRENGTH OF THE WINDS WITH NAM THE WEAKEST...GFS THE STRONGEST AND RUC IN THE MIDDLE. WOULD TEND TO FAVOR THE GFS AS IT HAS SEEMED TO PERFORM WELL LATELY SO WILL LEAN MORE IN THIS DIRECTION. GFS BUFR SOUNDINGS...ESPECIALLY IN THE EAST SHOW VERY WEAK SFC BASED INVERSION IN PLACE DURING THE MORNING DUE TO DEEP CAA BEHIND SHORTWAVE TROUGH...AND SUPPORT GUSTS AROUND 40KTS AND POSSIBLY SUSTAINED WINDS APPROACHING 28-30KTS AROUND 18Z. SINCE OTHER MODELS ARE NOT AS AGGRESSIVE WITH THE WINDS...WILL HEDGE BACK A BIT FROM THE GFS AND NOT ISSUE ANY KIND OF WIND ADVISORY BUT WILL HAVE GRIDS NEARING ADVISORY VALUES IN THE EARLY AFTERNOON. SREF/NAM/GFS ALL CONTINUE TO SHOW A SHARP GRADIENT IN MAX TEMPS ACROSS THE CWA...WITH COOLEST TEMPS ACTUALLY IN THE WARMER AIR MASS. GFS/NAM SOUNDINGS SUGGEST THAT WARMING ALOFT MAY BE TOO STRONG OUT WEST...PREVENTING MUCH OF A DEEPLY MIXED BOUNDARY LAYER TO DEVELOP. WITH REMAINING SNOW COVER THERE THAT MAY NOT BE UNREASONABLE...BUT WITH CHANGING AIRMASSES BUMPED UP TEMPS A BIT IN THE WEST. OUT EAST...DEEPLY MIXED BOUNDARY LAYER SHOULD OFFSET COLDER TEMPS ALOFT AND THINK MAX TEMPS TOMORROW SHOULD ONLY BE A FEW DEGREES COLDER THAN TODAY. OVERNIGHT LOWS WILL ONCE AGAIN BE ON THE DIFFICULT SIDE AS MODELS A BIT MORE AGGRESSIVE IN BRINGING IN THE WARMER AIR WITH AMPLIFYING RIDGE. THINK THAT CONDITIONS WILL BE PRETTY OPTIMAL FOR COOLING...BUT AM UNSURE ON THE IMPACT THE WARMER AIR ALOFT WILL HAVE. KEPT THE GENERAL IDEA OF PREVIOUS FORECAST BUT WARMED TEMPS SLIGHTLY. WED-THUR...LARGE RIDGE WILL CONTINUE TO BUILD INTO THE AREA LEADING TO CONTINUED WARMING AND SUBSIDENCE ACROSS THE REGION. WEAK SHORT WAVE TROUGH SLIDES ALONG THE PERIPHERY OF THE RIDGE ON THURSDAY WHICH SHOULD BRING LITTLE MORE THAN INCREASING CLOUDS ACROSS THE AREA...AS POINT SOUNDINGS INDICATE A VERY STRONG AND DRY SUBSIDENCE INVERSION ACROSS THE REGION. WILL CONTINUE THE WARMING TREND THROUGH THE PERIOD...TEMPERED SOMEWHAT BY UNCERTAINTY OF SNOWCOVER IMPACTS. .EXTENDED (FRIDAY-MONDAY)...EC AND OPERATIONAL GFS IN GENERAL AGREEMENT ON THE MEAN FLOW PATTERN DURING THE EXTENDED PERIOD. THERE ARE SLIGHT DIFFERENCES BETWEEN THEM IN TERMS OF STRENGTH AND TIMING OF SEVERAL SHORTWAVE TROUGHS SET TO MOVE THROUGH THE CWA DURING THE EXTENDED. WILL GO WITH A BLEND OF THE TWO FOR THIS FORECAST PACKAGE. FLOW BECOMES MORE ZONAL ON FRIDAY AS A LONGWAVE TROUGH STARTS TO AMPLIFY OVER THE WESTERN CONUS. WITH DRY SOUTHWESTERLY FLOW AT THE SURFACE AND ALOFT AND H85 TEMPS APPROACHING +10C...FRIDAY MAX TEMPS IN THE LOW TO MID 50S SEEM REASONABLE. HAVE SLIGHTLY LOWER TEMPS GOING OVER THE COLORADO COUNTIES AS I FEEL FAIRLY CERTAIN THERE WILL BE ENOUGH RESIDUAL SNOWPACK TO HOLD TEMPS DOWN A FEW DEGREES THERE. FIRST IN THE SERIES OF SHORTWAVE TROUGHS WILL PUSH THROUGH THE AREA LATE SATURDAY BUT SHOULD BRING LITTLE MORE THAN A CHANGE IN WIND DIRECTION AND SLIGHTLY COOLER TEMPS FOR SUNDAY. GFS IS BRINGING THE SECOND ONE IN FOR SUNDAY NIGHT/MONDAY MORNING BUT FEEL IT MAY BE A LITTLE TOO PROGRESSIVE. WENT WITH THE SLOWER EC SOLUTION KEEPING PRECIP OUT OF THE GRIDS FOR NOW. FOR MONDAY...CURSORY GLANCE AT THE 12Z GFS SHOWS A POTENTIAL WINTER STORM FOR THE AREA. 295K ISENTROPIC SURFACE SHOWING STRONG UPGLIDE AND ADVECTION OF 6-8 G/KG MIXING RATIOS. THIS IS MORE IN LINE IN TERMS OF TIMING WITH THE 00Z/31 EC WHICH SHOWS A SIMILAR SOLUTION BUT KEEPS BEST FORCING...AND THEREFORE PRECIP...JUST TO THE NORTHWEST OF THE CWA. WILL NEED TO MONITOR THIS AND POSSIBLY INTRODUCE PRECIP IN THE NEAR FUTURE IF THE MODELS COME INTO CONSENSUS. REGARDLESS OF PRECIP...MONDAY MAX TEMPS WILL BE MUCH COOLER WITH H85 TEMPS OF AROUND -3 TO -5C. && .AVIATION...GUSTY NORTHWEST WINDS TO 30KTS WILL PERSIST THROUGH SUNSET WITH DECENT SURFACE PRESSURE GRADIENT ACROSS THE AREA. MODELS INSISTENT ON KEEPING WINDS UP THROUGH THE NIGHT...THOUGH EXPECT GUSTS WILL SUBSIDE AS BOUNDARY LAYER DECOUPLES WITH SNOW STILL ON THE GROUND. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...WIND CHILL ADVISORY FROM 3 AM TO 9 AM MST TUESDAY FOR COZ090>092. && $$ JRM/CSF/JDK ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 418 PM EST MON DEC 31 2007 .SYNOPSIS... 20Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED OVERALL BROAD TROUGHING ACROSS NORTH AMERICA...WITH A RIDGE BUILDING UP ALONG THE IMMEDIATE WEST COAST. WITHIN THE BROAD TROUGH...THE MAIN FEATURES TO NOTE ARE A STRONG SHRTWV MOVING NE THROUGH MISSOURI...AN UPPER LOW OVER SOUTHERN MANITOBA AND A SHRTWV OVER NE BRITISH COLUMBIA. A WEAK SHRTWV IS ALSO NOTED OVER NE MN. ASSOCIATED WITH THIS SHRTWV AT THE SURFACE IS A 1009MB LOW OVER ISLE ROYALE...ALONG WITH SOME LIGHT SNOW OVER WESTERN LAKE SUPERIOR INTO THE WESTERN U.P. AS NOTED ON RADAR AND SURFACE OBS. 850MB TEMPS NEAR AND UNDER THE UPPER LOW WERE CHILLY...BUT NOT UNSEASONABLE WITH READINGS AT 12Z OF -14C AT INL...-15C AT CWPL AND -17C AT CYQD. SOUNDINGS FROM ALL THREE SITES ALSO DEPICTED PLENTY OF MOISTURE...WITH NEARLY SATURATED CONDITIONS FROM THE SURFACE THROUGH 500MB. FARTHER WEST...HIGH PRESSURE CAN BE SEEN BUILDING INTO TOWARDS THE PLAINS FROM THE WESTERN STATES...WITH A 1030-1040MB RIDGE STRETCHING FROM UTAH THROUGH ALBERTA. THE BACK SIDE OF THIS RIDGE IS WHERE WARMER AIR IS BUILDING UP...WHICH IS PROGGED TO HEAD EAST TOWARDS UPPER MI LATER THIS WEEK (SEE LONG TERM DISCUSSION FOR FURTHER DETAILS). && .SHORT TERM (TONIGHT THROUGH TUE NIGHT)... MAIN FORECAST CONCERN IS SNOWFALL AMOUNTS FROM THE UPCOMING LAKE EFFECT EVENT. TONIGHT...UPPER LOW OVER SOUTHERN MANITOBA WILL DROP SE TOWARDS THE MINNEAPOLIS AREA BY 12Z...WHILE THE STRONG SHRTWV OVER MISSOURI LIFTS INTO OHIO. GIVEN THE TRACK OF THE UPPER LOW...THE MAJORITY OF THE COLD AIR SEEN ON 12Z SOUNDINGS WILL BE SHUNTED SOUTHWARD RATHER THAN EASTWARD...BUT STILL SOME OF IT WILL MAKE IT ACROSS LAKE SUPERIOR. BY 12Z TUE...MODELS HAVE 850MB TEMPS DROPPING TO -12 TO -16C...COLDEST OVER WESTERN LAKE SUPERIOR CLOSER TO THE UPPER LOW. GIVEN THAT THIS AIR IS GENERALLY FLOWING FROM THE NW AND UPSTREAM SOUNDINGS ARE FAIRLY MOIST...THERE IS NO NEED TO WORRY ABOUT DRY AIR. HOWEVER...VERTICAL MOTION IS THE BIG QUESTION. SYNOPTICALLY SPEAKING...THE ONLY VERTICAL MOTION LOOKS TO OCCUR FROM THE SHRTWV OVER NE MN HEADING NE THIS EVENING. HAVE MAINTAINED SOME LOW CHANCE POPS ACROSS THE CWA FOR ANY LIGHT SNOW THAT THIS PRODUCES. GIVEN THE COLD AIR MOVING IN...THE OTHER SOURCE OF VERTICAL MOTION WILL BE THE INDUCED LAKE EFFECT. WITH THE SURFACE LOW OVER ISLE ROYALE PROGGED TO DROP SE...AND EVENTUALLY MERGE WITH THE SYSTEM HEADING UP TO OHIO...A GENERAL TROUGH OF LOW PRESSURE WILL SET UP FROM THUNDER BAY SE TO MUNISING. 950MB CONVERGENCE IS STRONGEST BEGINNING LATE THIS EVENING OVER THE WEST...IN PARTICULAR GOGEBIC AND ONTONAGON COUNTIES. SOUNDINGS DEPICT IN THIS AREA THE MAXIMUM VERTICAL MOTION EVENTUALLY INTERSECTING THE DENDRITIC GROWTH ZONE AFTER MIDNIGHT... SUGGESTING SOME DECENT SNOWFALL RATES SHOULD OCCUR. THUS THE GOING HEADLINES OUT THERE LOOK REASONABLE. THE REST OF THE U.P. MAY SEE SOME LIGHT SNOW OR FLURRIES AS CLOUDS STICK AROUND. THESE CLOUDS SHOULD HELP TO HOLD TEMPERATURES UP...WITH COLD ADVECTION THROUGH THE NIGHT THE MAIN FACTOR IN BRINGING READINGS DOWN. STAYED CLOSER TO WARMER GUIDANCE FOR LOWS. TUESDAY INTO TUESDAY NIGHT...UPPER LOW WILL HEAD DOWN INTO INDIANA BY 00Z WED AND THEN TO VIRGINIA BY 12Z WED. THIS TRACK IS STILL NOT ALL THAT FAVORABLE TO BRING TOO MUCH COLD AIR DOWN...AND IT REALLY IS NOT UNTIL LATER TUE NIGHT WHEN THE SHRTWV OVER NE BRITISH COLUMBIA MOVES DOWN INTO WESTERN WI...BRINGING AIR IN MORE SIMILAR TO ARCTIC ORIGIN. THIS IS GOOD FOR THE PURPOSE OF LAKE EFFECT AS MUCH OF THE VERTICAL MOTION PRODUCED BY LATENT HEAT FLUXES WILL INTERSECT THE DENDRITIC GROWTH ZONE. THUS...THE AREAS OF 950MB CONVERGENCE WILL DICTATE WHERE THE HEAVIEST SNOW FALLS. AT THE SURFACE...THE LOW PRESSURE TROUGH FROM THUNDER BAY THROUGH MUNISING IS PROGGED TO SWING SOUTH. HOW QUICK THIS OCCURS WILL DETERMINE AT LEAST WHEN THE HEAVIER SNOW WILL GET INTO THE NORTH CENTRAL U.P....SINCE WINDS TURN N TO NE BEHIND IT. THE GFS/CANADIAN ARE SLOWER TO BRING THE TROUGH SOUTH COMPARED TO THE NAM/LOCAL WRF-ARW...AND THUS HAVE DELAYED A BIT WHEN THE HEAVIER SNOW. STILL...IT LOOKS LIKE THERE WILL BE A PERIOD FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING WITH HEAVIER SNOW IN MARQUETTE COUNTY. BOTH SCENARIOS STILL LOOK GOOD FOR THE GOING HEADLINES IN GOGEBIC AND ONTONAGON COUNTIES...WITH THE STRONGEST CONVERGENCE STILL FOCUSED DURING THE DAY INTO EARLY MORNING HOURS IN GOGEBIC. WINDS TURNING NORTH AND THEN NE ARE NOT FAVORABLE FOR EITHER THE KEWEENAW OR LUCE/NORTHERN SCHOOLCRAFT...THUS NO HEADLINES ARE REQUIRED. SNOWFALL RATIOS OF 25 TO 1 ARE EXPECTED...WITH THE WINDS KEEPING THE RATIOS FROM GOING HIGHER. THESE RATIOS COULD GET HIGHER THOUGH ON TUESDAY NIGHT...THANKS TO COLDER AIR AND LIGHTER WINDS...BUT SYNOPTIC MOISTURE IS PROGGED TO DEPART. THUS...SNOWFALL SHOULD DIMINISH IN INTENSITY LATER TUESDAY EVENING. TEMPERATURES ARE EXPECTED TO ONLY CLIMB A FEW DEGREES ON TUESDAY DUE TO CONTINUED COLD ADVECTION...AND COULD FALL IN THE AFTERNOON. BROUGHT TEMPS UP A FEW DEGREES TUE NIGHT DUE TO WINDS THAT APPEAR MORE NORTHERLY...RESULTING IN MORE CLOUD COVER. && .LONG TERM (WEDNESDAY THROUGH NEXT MONDAY)... WED...LES WILL CONTINUE FOR NW FLOW FAVORED LOCATIONS AS 850 MB TEMPS REMAIN NEAR -18C. THE LONGER FETCH AND GREATER INVERSION HEIGHTS/MOISTURE DEPTH WILL BRING GREATER INTENSITY WITH LIGHT TO MODERATE ACCUMLUATIONS TO THE ERN CWA. OVER THE WEST...THE SHORTER FETCH LENGTH AND UPSTREAM DRYING FROM WRN LAKE SUPERIOR SHOULD RESULT IN MAINLY LIGHT ACCUMULATIONS. AS THE RIDGE BUILDS INTO THE REGION WED NIGHT...WINDS WILL STEADILY BACK WITH LOW LEVEL FLOW SHIFTING OFFSHORE FROM WEST TO EAST OVERNIGHT...ENDING ANY LES. A PERIOD OF DECOUPLED WINDS WITH CLEARING SKIES BEFORE SW FLOW INCREASES LATE SHOULD ALLOS TEMPS TO FALL BLO GUIDANCE FOR INLAND PORTIONS OF THE WEST. THU AND FRI...STRONG WAA WSW FLOW TAKES OVER AS A MID LEVEL TROUGH MOVES INTO THE WRN CONUS AND A BROAD/FLAT RIDGE EXPANDS INTO THE PLAINS AND GREAT LAKES. MDLS MOISTURE FIELDS SUGGEST THAT THE AIRMASS WILL REMAIN TO DRY TO SUPPORT MEASURABLE PCPN. FRI NIGHT INTO SAT...ENOUGH MOISTURE FINALLY MOVES TOWARD THE REGION WITH LOW LEVEL WINDS BACKING AND ALLOWING GULF MOISTURE TO MOVE TOWARD THE REGION. 00Z ECMWF AND 12Z GFS PARTIAL THICKNESS FIELDS AND SOUNDINGS SUGGEST POTENTIAL FOR SOME FREEZING DRIZZLE INTO SAT MORNING WITH A PERSISTENT 850-700 DRY LAYER. TEMP PROFILE WOULD BE BODERLINE FOR FROZEN PCPN BUT CANNOT RULE OUT SOME PATCHY LIGHT SNOW AT THIS TIME. WAA AND DIUNRAL WARMING SHOULD KEEP ANY LIGHT PCPN AS LIGHT RAIN OR DRIZZLE BY SAT AFTERNOON. SUN-MON...WHILE MODELS ARE IN GENERAL AGREEMENT WITH LARGE SCALE PATTERN FEATURING A BROAD TROF OVER THE WRN CONUS AND SW FLOW INTO THE GREAT LAKES...SIGNFICANT DIFFERENCES DEVELOP AND POOR RUN TO RUN CONTINUITY WAS OBSERVED WITH THE TIMING/STRENGTH OF SHORTWAVES MOVING THROUGH THE AREA. WHILE THE 00Z ECMWF WAS FASTER WITH STRONGER LEAD SHORTWAVE THAN THE 06Z/12Z GFS THE 12Z ECMWF IS NOW SIGNFICANTLY SLOWER. EVEN THOUGH A PERIOD OF RAIN IS LIKELY DURING THIS PERIOD...ONLY CHANCE POPS WERE INCLUDED DUE TO UNCERTAINTY IN WHEN IT MAY OCCUR. TEMPERATURES SHOULD REMAIN WELL ABOVE NORMAL WITH MIN READINGS ONLY APPROACHING FREEZING. SFC-700 MB TEMPS SUPPORT ONLY RAIN. SOME OF THE MODLE SOLUTIONS EVEN SUGGEST POTENTIAL FOR TSTMS WITH A STRONG SRLY LOW LEVEL JET AND SHOWALTER VALUES AROUND 0 AND 850 MB DEWPOINTS NEAR 8C. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... MVFR CEILINGS SHOULD PREVAIL THROUGH MUCH OF THE FCST PERIOD AT BOTH TAF SITES...DUE TO A COMBINATION OF LOW LEVEL MOISTURE ROTATING AROUND LOW PRESSURE OVER ISLE ROYALE DROPPING SE AND LAKE EFFECT CLOUDS THAT DEVELOP TONIGHT. THE VISIBILITY FORECAST IS A LITTLE MORE TRICKY. FOR CMX...VSBYS SHOULD COME DOWN SHORTLY AS OBSERVATIONS AND LATEST RADAR LOOP SHOW -SN WITH VSBYS OF MVFR OR IFR HEADING TOWARDS THERE. LAKE EFFECT SNOW SHOWERS SHOULD GET GOING IN THE WAKE OF THIS -SN EARLY THIS EVENING AS WINDS TURN NW. SINCE MODEL SOUNDINGS DO NOT LOOK TOO IMPRESSIVE WITH THE LAKE EFFECT THROUGH MUCH OF THE NIGHT...ONLY LOW MVFR VSBYS WERE FORECAST. VSBYS ARE EXPECTED TO DROP TO IFR VERY LATE IN THE NIGHT AND REMAIN INTO TUE AS COLDER AIR COMBINES WITH INCREASING WINDS TO CREATE MORE BLOWING OF THE SNOW. AT SAW...VSBYS MAY TAKE A LITTLE LONGER TO DROP...SINCE -SN IS STILL MOVING NE THROUGH CENTRAL WI. STILL...AN MVFR VSBY LOOKS LIKELY LATE THIS AFTERNOON AND EVENING. VSBYS SHOULD THEN IMPROVE THROUGH MUCH OF THE NIGHT WITH MUCH OF THE SNOW MOVING E OR NE OF THE AREA. LAKE EFFECT SNOW SHOWERS COMING OFF WESTERN LAKE SUPERIOR MAY BE ABLE TO DROP VSBYS TO MVFR LATE TONIGHT. HOWEVER...THINK THE BETTER CHANCE FOR LOWER VSBYS WILL COME TUE MORNING OR MORE LIKELY TUE AFTERNOON AS WINDS TURN TO THE NORTH...WHEN LAKE EFFECT COMES OFF CLOSER EASTERN LAKE SUPERIOR. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE SITTING OVER ISLE ROYALE THIS AFTERNOON WILL DROP SE TONIGHT AND TUE. COLD AIR FLOWING IN AND PRESSURES RISING RAPIDLY BEHIND THIS LOW WILL LIKELY PRODUCE 30 KT WINDS. MODELS HAVE COME DOWN A BIT ON WIND SPEEDS...BUT WITH THE RAPIDLY RISING PRESSURE...FEEL A MENTION OF GALE FORCE GUSTS IS STILL REQUIRED. WINDS WILL DIMINISH BELOW 30 KT FOR TUE NIGHT THROUGH WED NIGHT AS A RIDGE OF HIGH PRESSURE CROSSES. BEHIND THIS HIGH...A TIGHTENING PRESSURE GRADIENT IS EXPECTED ON THU AS LOW PRESSURE MOVES ACROSS CENTRAL CANADA. SW WINDS STILL LOOK LIKE THEY WILL INCREASE TO GALES ON LAKE SUPERIOR FOR THU INTO THU NIGHT...ESPECIALLY NORTH CENTRAL AND EAST AREAS. EXPECT WINDS TO DIMINISH TO 30 KT OR LESS FOR FRI INTO SAT AS THE LOW MOVES TO THE EAST...BUT A SOMEWHAT TIGHT PRESSURE GRADIENT REMAINS. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FROM 9 PM THIS EVENING TO MIDNIGHT CST TUESDAY NIGHT FOR MIZ009. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY FROM 10 AM TUESDAY TO 7 AM EST WEDNESDAY FOR MIZ005-006. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY FROM 10 PM THIS EVENING TO 1 AM EST WEDNESDAY FOR MIZ002. && $$ SYNOPSIS/SHORT TERM/MARINE...AJ LONG TERM...JLB AVIATION...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1230 PM EST MON DEC 31 2007 .AVIATION...CURRENT VIS SAT AND SFC OBS...SHOWING CLDS HAVE CLEARED OVER MUCH OF NRN MI...WHILE RADAR SHOWS A FEW LINGERING LAKE BANDS OVR NW LWR MI. THEREFORE WILL KEEP SOME MENTION OF VFR CIGS AND VSBY OVR APN AND TVC THIS AFTN...WHILE KEEPING SOME MVFR CIGS AND VSBY OVR PLN THIS AFTN DUE TO SOUTHWEST LAKE EFFECT SNOWS. A STORM SYSTEM OVR THE MIDWEST...WILL CONT TO DEEPEN THIS AFTN MOVING INTO THE NRN OHIO VALLEY BY THIS EVENING. AS THIS SYSTEM MOVES TOWARD THE SRN LAKES TONIGHT...EXPECT IFR CIGS AND VSBYS TO MOVE BACK INTO THE NRN LAKES REGION TONIGHT AND LINGER INTO TUESDAY. SWR && .UPDATE...ISSUED 1033 AM MON DEC 31 FAIRLY QUIET DAY ON TAP THROUGHOUT NORTHERN MICHIGAN...WITH THE EXCEPTION OF LINGERING LAKE EFFECT BAND ALONG/SOUTH OF THE STRAITS WHICH REMAINS THE PRIMARY FORECAST CHALLENGE. BAND REALLY WENT TO TOWN OVERNIGHT OWING TO ONSET OF DEEP SYNOPTIC MOISTURE IN ADVANCE OF WEAK SHORTWAVE PROGRESSING THROUGH WISCONSIN AS WELL AS PRONOUNCED 1000-850MB CONVERGENCE AXIS RUNNING THE LENGTH OF THE LAKE. BAND HAS SINCE WEAKENED WITH SOME DISRUPTION OF THE LOW LEVEL FLOW PER EARLY MORNING ONSET OF LAND BREEZE AS WELL AS PASSAGE OF WEAK UPPER WAVE AND LOSS OF -DIVQ. HOWEVER...OVERALL SFC FLOW REMAINS QUITE CONVERGENT PER RECENT OBS AND LATEST RUC/NAM PROGS THROUGH 18Z...AND WITH DELTA T/S MORE THAN SUFFICIENT (MID TEENS) AND INVERSION HEIGHTS NEARLY NON-EXISTENT IN THE PRESENCE OF STEEP LAPSE RATES (850-500MB RATES RUNNING SOME 7.5C/KM)...FORESEE NO REASON WHY SOME WEAK LAKE BANDING WON/T CONTINUE INTO THE AFTERNOON FOR THE TIP OF THE MITT COUNTIES. THUS GOING ADVISORY LOOKS LIKE A GOOD DEAL AS A FEW SPOTS (MAINLY EMMET COUNTY) COULD PICK UP A COUPLE FRESH INCHES INTO EARLY AFTERNOON BEFORE OVERALL PARAMETERS ON THE DECLINE PER INFLUX OF SLIGHTLY WARMER AIR ALOFT AND SHIFTING LOW LEVEL FLOW REGIME AS OHIO VALLEY STORM BEGINS TO TAKE SHAPE. ELSEWHERE...EARLY MORNING SYNOPTIC SNOW JUST ABOVE OVER AS WEAK 280-285K ISENTROPIC UPGLIDE WEAKENING WITH THE PASSAGE OF VORT AND DEPTH OF MOISTURE SHALLOWING. GIVEN LATEST RADAR TRENDS WILL JUST CALL IT FLURRIES FOR THE REMAINDER OF THE MORNING WITH THE EXCEPTION OF EASTERN UPPER WHERE WILL MAINTAIN SCATTERED LIGHT SNOW WITH MOISTURE DEPTH HOLDING FIRM PER FORECAST RAOBS. OTHERWISE...A MAINLY CLOUDY DAY ON TAP AREAWIDE...THOUGH COULD SEE A FEW BREAKS THROUGH THE DAY (ALREADY ONGOING ACROSS NORTHEAST LOWER WHERE FLOW WEAKLY DOWNSLOPE) BUT LIKELY NOT MUCH PER RENEWED PUSH OF MID/HIGH CLOUDS OFF TO THE SOUTH AND RESIDUAL THERMAL TROUGHING HANGING OUT OVERHEAD. ONE FINAL NOTE...HAVE ADDED MENTION OF PATCHY FREEZING FOG FOR MAINLY THE HIGHER TERRAIN THROUGH NOON AS OBS CONTINUE TO SHOW WIDESPREAD LIGHT FOG IN PLACE ALL THROUGH THE UPPER MIDWEST WITH PUSH OF WEAK THETA-E ADVECTION UP OVER SNOWPACK AND SOME HELP LOCALLY WITH SOUTHWEST FLOW RUNNING UP INTO THE HIGHER TERRAIN. HAVE ALREADY SEE LIGHT RIMING UP HERE ON THE HILL AND SUSPECT SIMILAR CONDITIONS IN PLACE CENTRAL CWA. LATEST NAM 30AGL COND PRES PLOTS SEEM TO HAVE A GOOD HANDLE ON THIS POTENTIAL...WITH SOME LOSS EXPECTED BY THE AFTERNOON AS SFC TEMPS CONTINUE TO WARM...THOUGH INTERESTING TO NOTE LATEST MAV GUIDANCE HANGS THE (RELATIVELY) LOW VISBYS IN THROUGH MUCH OF THE DAY FOR INTERIOR COUNTIES. LAWRENCE && .PREV DISCUSSION... /ISSUED 426 AM EST MON DEC 31 2007/ DISCUSSION...NEW LONG WAVE TROUGH DIGGING TOWARD 150W EARLY THIS MORNING WILL SET THE STAGE FOR A SHOT OF COLD AIR FOR THE WESTERN LAKES TO USHER IN THE NEW YEAR. THIS COLD PERIOD WILL BE SHORT LIVED HOWEVER...WITH BIG TIME HEIGHT RISES AND SOUTHWESTERLY FLOW ALOFT SETTING UP FOR THE LATTER HALF OF THE WEEK. SO LOOKING AT A WARM UP AKIN TO WHAT OCCURRED DURING THE EXACT SAME TIME PERIOD ONE YEAR AGO. FORECAST PROBLEMS IN THE NEAR TERM WILL DEAL FIRST WITH A NASTY LOOKING SNOW BAND OVER NORTHERN LAKE MICHIGAN. FOCUS THEN TURNS TO TWO SHORT WAVES ROTATING THROUGH MEAN CENTRAL NORTH AMERICAN MEAN TROUGH POSITION. ONE WAVE SLIDING INTO NE/KS EARLY THIS MORNING... AND WILL ZIP THROUGH THE OHIO RIVER VALLEY TONIGHT. WILL NEED TO EVALUATE SNOW THREAT WITH THIS SYSTEM...EVEN THOUGH THE BULK OF THE EFFECTS WILL BE SOUTH OF THE FORECAST AREA. A SECOND WAVE SPINNING ITS WAY OUT OF NORTHERN MANITOBA PER WATER VAPOR IMAGERY WILL DIG SOUTHEAST INTO THE OHIO VALLEY AND MID ATLANTIC IN THE TUESDAY/ WEDNESDAY TIME FRAME AS LONG WAVE TROUGH CONTINUES TO TRANSLATE EASTWARD. THIS LATTER WAVE WILL HELP PULL COLDER AIR ACROSS THE GREAT LAKES THROUGH THE MIDWEEK PERIOD...AND WILL GET THE LAKE EFFECT MACHINE GOING AGAIN LATER TUESDAY INTO MIDWEEK. FORECAST EVOLUTIONS IS SOMEWHAT COMPLEX WITH DECENT POTENTIAL FOR SNOWFALL TUESDAY. MORE ON THAT BELOW. TODAY/TONIGHT...AT THE ONSET THIS MORNING...LIGHT SNOW AND FLURRIES WERE FALLING ACROSS NORTHERN LOWER...WITH A FOCUSED AREA OF CONVERGENCE RESULTING IN A STRONG SNOW BAND OVER NORTHERN LAKE MICHIGAN FROM THE MANITOU AND FOX ISLANDS NORTHEAST INTO THE STRAITS AREA. RADAR RETURNS ARE IMPRESSIVE...WITH POCKETS OF 30-35 DBZ RETURNS WITH RADAR ESTIMATES OF 1-2 INCH/HOUR SNOWFALL RATES. FORTUNATELY...MUCH OF THIS IS OFFSHORE THOUGH THE NORTHERN END IS POKING INTO SOUTHERN MACKINAC COUNTY. THIS BAND IS ACTUALLY JUST THE NORTHER END OF A BAND THAT SNAKES ITS WAY BACK INTO SOUTHERN LAKE MICHIGAN...WITH RADAR INDICATIONS OF ONE OR MORE MESOSCALE VORTICES SPINNING ALONG THIS LINE OF CONVECTION ACROSS CENTRAL AND SOUTHERN LAKE MICHIGAN. ON THE LARGE SCALE...SYNOPTIC LIGHT SNOW ASSOCIATED WITH NORTHERN FRINGES OF SMALL SCALE VORT CENTER NOTED ON WATER VAPOR SLIDING ACROSS FAR SOUTHERN LOWER...PROBABLY SOME CONTRIBUTION FROM ANOTHER MID LEVEL WAVE OVER CENTRAL WI. 00Z UPPER AIR ANALYSES/SOUNDINGS SHOW DRIER AIR ACROSS IA/MO/IL THAT MOVE INTO LOWER MI LATER TODAY...WHICH COMBINED WITH LOSS OF FORCING SHOULD CONFINE CURRENT LIGHT SNOW PATTERN TO THE FIRST HALF OF THE DAY FOR THE MOST PART. IN ADDITION TO THE SYNOPTIC SNOW...REMNANTS OF THE SOUTHERN PORTION OF THE AFOREMENTIONED LAKE MICHIGAN BAND WILL BRING SOME BURSTS OF HEAVIER SNOW TO WESTERN LOWER FOR A TIME THIS MORNING AS THOSE CONVECTIVE ELEMENTS HEAD INLAND. BIGGER QUESTION IS WHAT TO DO WITH THE BAND OVER NORTHERN LAKE MICHIGAN? INDICATIONS ARE THAT CONVERGENCE WILL WEAKEN THIS MORNING AS LOW LEVEL FLOW FORECAST TO BECOME MORE UNIFORMLY SOUTHWEST. BUT DOES APPEAR THAT THERE COULD BE A SEVERAL HOUR WINDOW THIS MORNING WITH HEAVY SNOWFALL RATES ACROSS PARTS OF CHARLEVOIX/EMMET/EXTREME NORTHERN CHEBOYGAN/ SOUTHEASTERN MACKINAC COUNTIES. EVEN AS THE MAIN BAND MOVES INLAND AND WEAKENS...SOUTHWEST FLOW LES PARAMETERS ARE NOT BAD EVEN WITH MARGINALLY WARM (AROUND -11C) 850MB TEMPERATURES. LAPSE RATES ARE AT OR GREATER THAN MOIST ADIABATIC THROUGH 500MB...WITH FORECAST LAKE INDUCED CAPES A DECENT 400-450 J/KG THROUGH MIDDAY BEFORE DROPPING DURING THE AFTERNOON AS 850MB TEMPERATURES CONTINUE TO WARM AND INVERSION BECOMES A BIT BETTER DEFINED WITH WEAK DOWNWARD FORCING. GIVEN THIS THINKING...WENT AHEAD EARLIER AND PUT UP AN LES ADVISORY FOR THE ABOVE LISTED COUNTIES THROUGH THE AFTERNOON HOURS. RAN WITH ACCUMULATIONS OF 3-7 INCHES FROM NOW THROUGH LATE AFTERNOON. WANTED TO GET SOMETHING OUT BEFORE THE HEAVIER SNOWFALL RATES MOVED IN (WHICH WOULD HAVE OCCURRED PRIOR TO SCHEDULED FORECAST ISSUANCE). JUST ANOTHER NORTHERN MICHIGAN SNOW "FLASH FLOOD" EVENT... FOR TONIGHT...ATTENTION WILL BE FOCUSED ON SHORT WAVE COMING OUT OF NE AS IT TRACKS ACROSS THE OHIO VALLEY. GUIDANCE TREND HAS BEEN A BIT FARTHER SOUTH WITH TIME...WITH A SURFACE LOW TRACK NOW ACROSS IN/OH/LAKE ERIE. GIVEN THE PENCHANT FOR SYSTEMS TO END UP TRACKING FARTHER NORTH SO FAR THIS COLD SEASON...MIGHT END UP LOOKING FOOLISH TO SAY THAT THERE IS REASONABLE CONFIDENCE THAT THIS SYSTEM WILL REMAIN FAR ENOUGH SOUTH TO OFFER JUST A GLANCING BLOW TO CENTRAL LOWER MI COUNTIES. BUT THERE...I JUST WROTE IT. AT THE VERY LEAST...THE TREND HAS BEEN AWAY FROM US...UNLIKE IN PRIOR SYSTEMS WHERE THE TREND WAS FARTHER NORTH WITH TIME. GIVEN THE CURRENT TRACK OF THE WAVE...UNLESS SOMETHING FUNKY HAPPENS ALOFT...THE NORTHERN OHIO VALLEY ROUTE LOOKS PRETTY GOOD. SOME QG FORCING SPREADS INTO NORTHERN LOWER...BUT PROVIDED MID LEVEL DEFORMATION ZONE SETS UP ACROSS SOUTHERN LOWER AS FORECAST...THEN THE MAJORITY OF THE ACTION WILL STAY OUT OF THE FORECAST AREA. WILL CARRY HIGHEST POPS EAST OF AN APN-HTL LINE...CLOSEST TO PASSING SYSTEM TO THE SOUTH AND ACKNOWLEDGING POTENTIAL FOR SOME SHALLOW LAKE HURON LES TO GET GOING OVERNIGHT AS WINDS TAKE ON AN EASTERLY COMPONENT. NEW YEAR`S DAY TUESDAY...AS SURFACE LOW PULLS AWAY FROM LAKE ERIE... TROUGH AXIS WILL BE HANGING BACK ACROSS LOWER MI...EVENTUALLY TURNING INTO THE LEADING EDGE OF THE COLD AIR DROPPING IN FROM ONTARIO. LINGERING DEEP MOISTURE AND CONTINUED STEEP LAPSE RATES THROUGH THE COLUMN WILL KEEP THE THREAT FOR SNOW GOING ACROSS THE FORECAST AREA. BUT THE BIGGER PROBLEM MAY BE THE LAKE ENHANCEMENT... AND AM BECOMING INCREASINGLY CONCERNED ON THE LAKE MICHIGAN SIDE. ALTHOUGH 850MB TEMPERATURES ARE SOMEWHAT MARGINAL (STILL AROUND -11C)...STEEP LAPSE RATES YIELD NO REAL INVERSION (FORECAST LAKE INDUCED CAPES CLIMBING INTO THE 400-500 J/KG RANGE DURING THE AFTERNOON)...DEEP LAYER MOISTURE PERSISTING...AND A FAIRLY CONSISTENT WIND DIRECTION THROUGH MUCH OF THE DAY (340 DEGREES OR SO) TARGETS AREAS ALONG/WEST OF US-131 FOR DECENT SNOWFALL. INVERTED TROUGH AXIS A COMPLICATING FACTOR...THOUGH NOT FORECAST TO SWEEP INTO CENTRAL LAKE MICHIGAN UNTIL LATE IN THE DAY. COULD END UP WITH AN AREA OF CONVECTION THAT DEVELOPS ALONG THE TROUGH AND ENHANCES SNOWFALL POTENTIAL. AS FOR SNOW AMOUNTS...WILL START WITH HIGH END ADVISORY CRITERIA (4-6 INCHES) BUT AM CONCERNED ENOUGH THAT BELIEVE A LAKE EFFECT SNOW WATCH IS WARRANTED FOR TUESDAY INTO TUESDAY NIGHT FOR COUNTIES ALONG/WEST OF M-37. IF IT ENDS UP TRANSITIONING TO AN ADVISORY THAT IS FINE. INTERESTINGLY ONCE THE COLDER AIR ARRIVES TUESDAY NIGHT...INVERSION HEIGHTS BEGIN TO TANK AND WINDS WILL PROBABLY BE SOMEWHAT VARIABLE FROM NORTHEAST TO NORTH FOR A TIME. ALSO PLAN ON CARRYING SOME LIGHTER ACCUMULATIONS ON THE LAKE HURON SIDE WITH NORTH- NORTHEAST LOW LEVEL FLOW ON BACKSIDE OF SURFACE TROUGH. MARINE ISSUES...NO HEADLINES THROUGH TONIGHT. WILL NEED TO CONSIDER SMALL CRAFT ADVISORIES AT LEAST AROUND THE NORTHERN LOWER NEARSHORE ZONES ON TUESDAY. EARLY EXTENDED PERIOD (WEDNESDAY THROUGH FRIDAY)...NORTH-NORTHWEST FLOW LAKE EFFECT WILL CONTINUE TO BE AN ISSUE INTO WEDNESDAY... BEFORE DEEP LAYER RIDGING/STRONG HEIGHT RISES ALOFT PUSH INTO THE UPPER MIDWEST/GREAT LAKES ON THURSDAY. THIS WILL SHUT THE LAKE EFFECT OFF AS WARMER AIR FLOODS NORTHWARD. EXTENDED GUIDANCE STILL LOOKS DRY FOR THURSDAY/FRIDAY EVEN AS WARM ADVECTION COMMENCES. THURSDAY TEMPERATURES EXPECTED TO BE SEASONABLY COLD...BEFORE A NOTICEABLE WARM UP STARTS FRIDAY. NO CHANGES NECESSARY TO EXTENDED GRIDS (AS IF THE ABOVE ISSUES WEREN`T ENOUGH ALREADY). JPB && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR MIZ015>017-019. LAKE EFFECT SNOW WATCH FROM LATE TONIGHT THROUGH LATE TUESDAY NIGHT FOR MIZ020-025-026-031-032. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 1202 PM MST MON DEC 31 2007 .UPDATE...MINOR UPDATE TO CHANCE FOR PRECIPITATION THIS AFTERNOON ALONG THE I-90 CORRIDOR FROM MISSOULA TO BUTTE. && .DISCUSSION...SNOW SHOWERS WILL CONTINUE OVER THE SOUTHERN SWAN VALLEY SOUTH THROUGH SEELEY LAKE AND ALSO OVER THE MOUNTAINS SUROUNDING THE MISSOULA/BITTERROOT VALLEYS. THESE SNOW SHOWERS WILL OCCATIONALLY MOVE OVER THE MISSOULA AND BITTERROOT VALLEYS PRODUCING LITTLE IF ANY ACCUMULATION AS THE MOVE TO THE SOUTHEAST. I STILL EXPECT THESE SHOWERS TO DISSIPATE LATE THIS AFTERNOON AS THE APPROACHING UPPER LEVEL RIDGE BRINGS A MARKED DECREASE IN ATMOSPHERIC INSTABILITY. && AVIATION...SCATTERED SNOW SHOWERS WILL OBSCURE MOUNTAINS AND PEAKS AGAIN TODAY. HOWEVER...SKIES SHOULD CLEAR OVERNIGHT IN MANY AREAS ALLOWING PATCHY FOG TO FORM TUESDAY MORNING. && .PREV DISCUSSION... /ISSUED 1011 AM MST MON DEC 31 2007/ UPDATE...MADE SOME MINOR CHANGES TO THE CHANCE FOR PRECIPITATION AND SKY COVER FORECAST FOR TODAY. DISCUSSION...SNOW SHOWER ACTIVITY THIS MORNING HAS BEGUN TO DECREASE IN ITS INTENSITY PER WARMING CLOUD TOPS ON INFRARED SATELLITE IMAGERY. THE LATEST RUC MODEL ANALYSIS INDICATES THE HIGHEST PROBABILITY FOR SNOW SHOWERS TODAY WILL LIE ACROSS THE SEELEY LAKE REGION AND OVER THE CLEARWATER/BITTERROOT MOUNTAINS ALONG THE IDAHO/MONTANA BORDER. I ALSO RAISED THE CHANCE FOR PRECIPITATION UP THE SOUTHERN BITTERROOT VALLEY AS I BELIEVE THE SHOWERS WHICH DEVELOP OVER THE MOUNTAINS WILL OCCASIONALLY MOVE OVER THE VALLEY. LITTLE IF ANY ACCUMULATING SNOWFALL IS EXPECTED WITH THESE SHOWERS. OTHERWISE THE FORECAST LOOKS GOOD AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BEGIN TO ESTABLISH IT`S REIGN TONIGHT. PREV DISCUSSION... /ISSUED 313 AM MST MON DEC 31 2007/ DISCUSSION...LINGERING SNOW SHOWERS WILL CONTINUE IN THE MOUNTAINS TODAY AS LINGERING MOISTURE TAKES ADVANTAGE OF LOW TO MID LEVEL INSTABILITY IN THE ATMOSPHERE AND AN UPPER LEVEL JET STREAM THAT WILL MOVE OVER WESTERN MONTANA THIS AFTERNOON. PRECIPITATION WILL TAPER OFF OVERNIGHT AS AN UPPER LEVEL RIDGE PUSHES IN FROM THE WEST. AS SKIES CLEAR TOWARD DAYBREAK ON TUESDAY...STRONG RADIATIONAL COOLING WILL STABILIZE THE VALLEYS. SOME PATCHY FREEZING FOG WILL BE POSSIBLE IN THE VALLEYS AND CANYONS. SOUTHEASTERLY PRESSURE GRADIENTS WILL BEGIN TO TIGHTEN CONSIDERABLY ON TUESDAY NIGHT AND WEDNESDAY...VALLEY LOCATIONS SHOULD BE ABLE TO MIX OUT. ALTHOUGH THE PRESSURE GRADIENT ORIENTATION IS NOT IDEAL FOR HIGH WINDS ON THE CAMAS PRAIRIE OF IDAHO...THEY SHOULD STILL BE STRONG ENOUGH TO WARRANT THE ISSUANCE OF AT LEAST A WIND ADVISORY FOR THE TUESDAY NIGHT-WEDNESDAY PERIOD. WEDNESDAY NIGHT THROUGH MONDAY...THE STRONG SOUTHERLY PRESSURE GRADIENT SHOULD SCOUR OUT MUCH OF THE COLDER AIR TRAPPED IN THE VALLEYS BY WEDNESDAY NIGHT. A WARM AIRMASS WILL BEGIN PUSHING INTO THE AREA FROM THE SOUTH AND TEMPERATURES SHOULD WARM UP ON THURSDAY AND FRIDAY AND PUSH SNOW LEVELS ABOVE SOME VALLEY FLOORS. THURSDAY WILL BE RELATIVELY DRY WITH CHANCES FOR PRECIPITATION JUST ALONG THE IDAHO-MONTANA BORDER. AN UPPER LEVEL LOW BEGINS TO APPROACH OFF THE WASHINGTON COAST AND WILL PUSH MOISTURE AND ENERGY OVER THE AREA AGAIN ON FRIDAY. THE CONTINUED SOUTHERLY FLOW FRIDAY WILL KEEP LOWER VALLEYS AS RAIN THROUGH THE DAY BUT CHANGE OVER TO SNOW BY SATURDAY AS A COLD FRONT SWINGS THROUGH OVERNIGHT. THE WET PATTERN CONTINUES THROUGH SUNDAY AND MONDAY AS THE UPPER LEVEL TROUGH BROADENS OVER THE WESTERN UNITED STATES. MODELS ARE INDICATING A SURFACE LOW MOVING OVER THE SOUTHWEST MONTANA ON MONDAY WHICH IS A GOOD SETUP FOR A SNOW EVENT ACROSS THE WEST CENTRAL PART OF THE STATE. HOWEVER...GIVEN THE LENGTH OF TIME THIS IS OUT CONFIDENCE IS NOT VERY HIGH AT THIS POINT. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && $$ SHORT TERM...DICKERSON LONG TERM....FOSTER AVIATION...DICKERSON mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MISSOULA MT 1011 AM MST MON DEC 31 2007 .UPDATE...MADE SOME MINOR CHANGES TO THE CHANCE FOR PRECIPITATION AND SKY COVER FORECAST FOR TODAY. && .DISCUSSION...SNOW SHOWER ACTIVITY THIS MORNING HAS BEGUN TO DECREASE IN ITS INTENSITY PER WARMING CLOUD TOPS ON INFRARED SATELLITE IMAGERY. THE LATEST RUC MODEL ANALYSIS INDICATES THE HIGHEST PROBABILITY FOR SNOW SHOWERS TODAY WILL LIE ACROSS THE SEELEY LAKE REGION AND OVER THE CLEARWATER/BITTERROOT MOUNTAINS ALONG THE IDAHO/MONTANA BORDER. I ALSO RAISED THE CHANCE FOR PRECIPITATION UP THE SOUTHERN BITTERROOT VALLEY AS I BELIEVE THE SHOWERS WHICH DEVELOP OVER THE MOUNTAINS WILL OCCASIONALLY MOVE OVER THE VALLEY. LITTLE IF ANY ACCUMULATING SNOWFALL IS EXPECTED WITH THESE SHOWERS. OTHERWISE THE FORECAST LOOKS GOOD AS AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BEGIN TO ESTABLISH IT`S REIGN TONIGHT. && .AVIATION...SCATTERED SNOW SHOWERS WILL OBSCURE MOUNTAINS AND PEAKS AGAIN TODAY. HOWEVER...SKIES SHOULD CLEAR OVERNIGHT IN MANY AREAS ALLOWING PATCHY FOG TO FORM TUESDAY MORNING. && .PREV DISCUSSION... /ISSUED 313 AM MST MON DEC 31 2007/ DISCUSSION...LINGERING SNOW SHOWERS WILL CONTINUE IN THE MOUNTAINS TODAY AS LINGERING MOISTURE TAKES ADVANTAGE OF LOW TO MID LEVEL INSTABILITY IN THE ATMOSPHERE AND AN UPPER LEVEL JET STREAM THAT WILL MOVE OVER WESTERN MONTANA THIS AFTERNOON. PRECIPITATION WILL TAPER OFF OVERNIGHT AS AN UPPER LEVEL RIDGE PUSHES IN FROM THE WEST. AS SKIES CLEAR TOWARD DAYBREAK ON TUESDAY...STRONG RADIATIONAL COOLING WILL STABILIZE THE VALLEYS. SOME PATCHY FREEZING FOG WILL BE POSSIBLE IN THE VALLEYS AND CANYONS. SOUTHEASTERLY PRESSURE GRADIENTS WILL BEGIN TO TIGHTEN CONSIDERABLY ON TUESDAY NIGHT AND WEDNESDAY...VALLEY LOCATIONS SHOULD BE ABLE TO MIX OUT. ALTHOUGH THE PRESSURE GRADIENT ORIENTATION IS NOT IDEAL FOR HIGH WINDS ON THE CAMAS PRAIRIE OF IDAHO...THEY SHOULD STILL BE STRONG ENOUGH TO WARRANT THE ISSUANCE OF AT LEAST A WIND ADVISORY FOR THE TUESDAY NIGHT-WEDNESDAY PERIOD. WEDNESDAY NIGHT THROUGH MONDAY...THE STRONG SOUTHERLY PRESSURE GRADIENT SHOULD SCOUR OUT MUCH OF THE COLDER AIR TRAPPED IN THE VALLEYS BY WEDNESDAY NIGHT. A WARM AIRMASS WILL BEGIN PUSHING INTO THE AREA FROM THE SOUTH AND TEMPERATURES SHOULD WARM UP ON THURSDAY AND FRIDAY AND PUSH SNOW LEVELS ABOVE SOME VALLEY FLOORS. THURSDAY WILL BE RELATIVELY DRY WITH CHANCES FOR PRECIPITATION JUST ALONG THE IDAHO-MONTANA BORDER. AN UPPER LEVEL LOW BEGINS TO APPROACH OFF THE WASHINGTON COAST AND WILL PUSH MOISTURE AND ENERGY OVER THE AREA AGAIN ON FRIDAY. THE CONTINUED SOUTHERLY FLOW FRIDAY WILL KEEP LOWER VALLEYS AS RAIN THROUGH THE DAY BUT CHANGE OVER TO SNOW BY SATURDAY AS A COLD FRONT SWINGS THROUGH OVERNIGHT. THE WET PATTERN CONTINUES THROUGH SUNDAY AND MONDAY AS THE UPPER LEVEL TROUGH BROADENS OVER THE WESTERN UNITED STATES. MODELS ARE INDICATING A SURFACE LOW MOVING OVER THE SOUTHWEST MONTANA ON MONDAY WHICH IS A GOOD SETUP FOR A SNOW EVENT ACROSS THE WEST CENTRAL PART OF THE STATE. HOWEVER...GIVEN THE LENGTH OF TIME THIS IS OUT CONFIDENCE IS NOT VERY HIGH AT THIS POINT. && .MSO WATCHES/WARNINGS/ADVISORIES... MT...NONE. ID...NONE. && $$ SHORT TERM...DICKERSON LONG TERM....FOSTER AVIATION...DICKERSON mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 216 PM CST MON DEC 31 2007 .SHORT TERM...TONIGHT THROUGH THURSDAY. WV SATL IMAGERY THIS AFTERNOON SHOWING IMPRESSIVE RIDGING BUILDING INTO THE WESTERN STATES WITH NEXT SYSTEM DIGGING OFF THE PAC NW COAST. STRONG JET SEGMENT BETWEEN THE TWO FEATURES WAS ADVECTING STOUT PAC MOISTURE INTO WESTERN CANADA. OVER THE REST OF THE CONUS... POLAR JET/LARGE BROAD TROF WITH EMBEDDED VORT MAXES ROTATING THROUGH ASSOCIATED WITH UPPER LOW CENTERED OFF WEST COAST OF GREENLAND. AT THE SURFACE...LOW PRESSURE WAS TRACKING EWD THRU ERN MO WITH LEADING EDGE OF ATTENDANT COLD FRONT EXTENDING FROM MO TO SRN TX. MEANWHILE...LEADING EDGE OF ARCTIC AIRMASS INVOF USA/CANADA BORDER POISED TO SWEEP SWD INTO THE PLAINS/MS VLY LATE TONIGHT. REGIONAL RADAR PIX WAS SHOWING RETURNS PUSHING THRU THE DAKOTAS IN ASSOCIATION WITH PASSING IMPULSE. NAM/GFS/RUC DO PLACE SMALL AREA OF QPF IN THE CWA OVERNIGHT FROM POCKET OF LIFT WITH VIGOROUS SHORTWAVE ROTATING THRU. MOISTURE IS WEAK...THEREFORE THINK SLGT POPS BEST FIT FOR NOW. ARCTIC PLUNGE ON TUESDAY SENDS TEMPS PLUMMETING INTO THE SINGLE DIGITS NRN CWA AND LOW TEENS SOUTH. CORE OF COLD AIRMASS SINKS SWD THRU THE DAY...AND EVENTUALLY SETTLES INVOF THE OHIO VLY BY LATE TUESDAY AFTERNOON. BY WEDNESDAY MORNING...LIGHT WINDS/CLEAR SKIES WILL ALLOW LOWS TO FALL BELOW ZERO. AFTER THAT...THE MUCH ANTICIPATED WARM UP BEGINS IN EARNEST WITH HIGHS PUSHING INTO THE MID/UPPER 30S THURSDAY WITH THE TREND CONTINUES INTO THE EXTENDED PERIODS. .LONG TERM...THURSDAY NIGHT THROUGH MONDAY TEMPERATURES WILL PROVIDE THE PRIMARY CHALLENGES DURING THIS PERIOD. SNOWCOVER INITIALLY SHOULD HELP HOLD TEMPERATURES DOWN. WENT WITH LOWS IN THE UPPER TEENS AND LOWER 20S FOR THURSDAY NIGHT WITH HIGHS FRIDAY IN THE UPPER 30S AND LOWER 40S. EXPECT LOWS IN THE 20S FROM SATURDAY INTO MONDAY WITH HIGHS IN THE 40S. SOME PLACES COULD BE A LITTLE WARMER THAN THAT...BUT WILL ADDRESS THAT ONCE IT GETS INTO THE SHORT TERM. MODELS ARE IN GOOD AGREEMENT WITH THE LARGE SCALE PATTERN. AT THE BEGINNING OF THIS PERIOD...500 MB PATTERN INDICATES A RIDGE ACROSS THE CENTRAL CONUS AND TROUGH JUST OFF THE WEST COAST. THIS TROUGH DIGS INTO THE WESTERN U.S. OVER THE WEEKEND. A SHORTWAVE DOES MOVE OUT OF THIS TROUGH INTO THE NORTHERN AND CENTRAL PLAINS FOR SUNDAY. HOWEVER...MAIN ENERGY WILL REMAIN MUCH FARTHER WEST. 06Z RUN OF THE GFS STARTED GENERATING SOME LIGHT PCPN FOR AREAS TO OUR SOUTH AND EAST LATE FRIDAY NIGHT INTO SUNDAY. IT DID DID GENERATE SOMETHING IN OUR AREA SUNDAY...BUT HIGHER QPF WAS OVER MISSOURI AND IOWA. 00Z RUN OF THE ECMWF WAS DRY FOR OUR AREA. THE 12Z GFS DID SHOW SOME PCPN IN OUR AREA SUNDAY AND SUNDAY NIGHT. IF FUTURE MODEL RUNS START TO HAVE MORE AGREEMENT...WE CAN ADD SOME MENTION OF PCPN LATER. IT DOES APPEAR THAT THERE IS GOING TO BE A BETTER CHANCE FOR PCPN FROM MONDAY NIGHT INTO WEDNESDAY...AS THE TROUGH MOVES INTO THE REGION. && .AVIATION... FOR TAF SITES KOMA...KLNK AND KOFK. TIGHT PRESSURE GRADIENT AND STRONG COLD ADVECTION HAVE RESULTED IN AN EXTENSIVE CLOUD SHIELD FROM THE DAKOTAS INTO NORTHEAST 1/4 OF NEBRASKA. GRADIENT AND NORTH SURFACE WIND FORECAST TO PERSIST INTO TUESDAY MORNING. SOLID CLOUD DECK CLOUDS IN 020-035 RANGE EXPECTED TO FILL INTO EASTERN NEBRASKA BY 00Z. SNOW FLURRIES ARE ALSO LIKELY TONIGHT AT TIMES WITH VISIBILITY GENERALLY GREATER THAN 3 MILES. PERSISTENT COLD ADVECTION FORECAST TO KEEP CLOUD COVER UNTIL AT LEAST 18Z TUESDAY. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ DEE/MILLER/SS ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 353 PM EST MON DEC 31 2007 .SYNOPSIS... HIGH PRESSURE WILL PREVAIL THROUGH EARLY TUESDAY. A STRONG COLD FRONT WILL MOVE ACROSS THE AREA TUESDAY AFTERNOON. A LARGE AREA OF HIGH PRESSURE WILL BUILD ACROSS THE AREA FROM THE WEST WEDNESDAY AND THURSDAY...BRINGING A COLD AND VERY DRY AIRMASS TO THE AREA. THIS AREA OF HIGH PRESSURE WILL CREST ACROSS THE AREA ON FRIDAY AND RIDGE ACROSS THE AREA FROM THE EAST OVER THE WEEKEND. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... AS OF 3 PM MONDAY...FRONTAL BOUNDARY REMAINING OVER OFF SHORE COASTAL WATERS WILL BUCKLE TONIGHT AS AMPLIFIED UPPER SHORTWAVE TROF LIFTS TO THE EASTERN GREAT LAKES AND PULLS THIS BOUNDARY INLAND FOR A FEW HOURS MAINLY BETWEEN THE 06Z AND 12Z TIME FRAME. SREF NOT SHOWING MORE THAN A 40 PERCENT CHC OF ANY MEASURABLE PCP JUST ALONG THE COAST...MAINLY OVER THE CAPE FEAR AREA. RUC SHOWING PCP WATER REMAINING LESS THAN A HALF INCH OVER ALL OF THE CWA EXCEPT A FINE LINE ALONG THE COAST BETWEEN 06Z AND 12Z. AT THIS POINT WILL CONTINUE WITH PREVIOUS FORECAST AND CONTINUE WITH MAINLY CLEAR SKIES THROUGH THIS EVENING AND THEN PUSH CLOUDS OVER COASTAL COUNTIES...BUT KEEP SLIGHT CHC PCP CONFINED TO OFF SHORE COASTAL WATERS. KEPT TEMPS UP A LITTLE BIT MORE ALONG THE COAST DUE TO CLOUDS AND MORE EASTERLY FLOW OVERNIGHT. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...COLD FRONT IS EXPECTED TO SWEEP ACROSS THE AREA TUE AFTERNOON. TEMPS SHOULD LEVEL OFF BY MID AFTERNOON AND THEN FALL DURING THE LATE AFTERNOON. INFLUX OF DRY AND CHILLY AIRMASS IS IMPRESSIVE WITH H8 TEMPS DROPPING TO -15 DEG C BY WED MORNING. WINDS WILL STAY UP TUE NIGHT...AND SO LITTLE VARIATION IN TEMPS FROM INLAND AREAS TO THE COAST. ALL AREAS WILL BE IN THE MID AND UPPER 20S BY 12Z WED. GUSTY NW WINDS WILL ADD TO THE CHILL WED MORNING WITH WIND CHILLS DOWN IN THE TEENS. WINDS SUSTAINED AT 15 TO 20 MPH WILL GUST TO AROUND 30 MPH AS HIGHER WINDS ALOFT ARE MIXED TO THE SURFACE. DEWPOINTS WILL BE DROPPING INTO THE SINGLE DIGITS BY LATE MORNING WED...AN INDICATION OF JUST HOW DRY THE UPCOMING AIRMASS WILL BE. EVEN WITH SUNSHINE...TEMPS WILL STRUGGLE TO REACH 40 DEGREES WED AFTERNOON. COLDEST NIGHT THIS PERIOD WILL BE WED NIGHT AS WINDS DIMINISH AFTER SUNSET. WINDS MAY NOT FULLY DECOUPLE UNTIL LATE IN THE NIGHT...AND SO THE FULL RADIATIONAL COOLING AFFECTS WILL BE DELAYED. HOWEVER...ALL AREAS WILL BE WELL DOWN IN THE 20S WITH MANY COMMUNITIES IN THE LOWER TO MID TEENS BY THU MORNING. .LONG TERM /THURSDAY THROUGH MONDAY/... AS OF 3 PM MONDAY...HIGH PRESSURE BUILDS IN FROM THE W ON THU WITH THE CENTER OF THE HIGH SLOWLY MOVING E AND OFF THE COAST BY SAT. UPPER TROF ASSOCIATED WITH THE COLD AIR MASS MOVES OFF THE COAST AS HIGH BUILDS IN. TEMPERATURES WILL STARTING TO MODERATE ON THU...THOUGH TEMPERATURES WILL STILL BE WELL BELOW CLIMO...BY 10 DEGREES OR MORE. TEMPS WILL RETURN TO NEAR CLIMO BY THE END OF THE WEEK AS SRLY FLOW AROUND THE BACKSIDE OF THE HIGH DEVELOPS. GFS CONTINUES TO DEPICT A COASTAL TROF DEVELOPING OVER THE WEEKEND BUT THE LATEST ECMWF...WHILE STILL SHOWING A WEAK TROF...IS NOT DEPICTING A FEATURE THAT WILL HAVE A SIGNIFICANT IMPACT ON THE REGION. GIVEN THE LACK OF AGREEMENT BETWEEN THE GFS/ECMWF AND THE LENGTH OF TIME INVOLVED WITH THE FORECAST HAVE DECIDED TO GO WITH A CLOUDY BUT DRY FORECAST LATE IN THE PERIOD. && .AVIATION /18Z MONDAY THROUGH SATURDAY/... VFR CONDITIONS THROUGH THE FORECAST PERIOD. HIGH PRESSURE SLIDES OFFSHORE...SWINGING THE WINDS TO THE SOUTHEAST LATER THIS AFTERNOON. GFS RATHER PESSIMISTIC...BRINGING RETURN FLOW OVERNIGHT WITH EVEN A CHANCE OF PRECIP. DID NOT LIKE THIS SCENARIO AND STUCK BASICALLY WITH THE NAM...WITH A HIGH STRATA CU CEILING WORST CASE. WINDS BECOME WESTERLY AND GUSTY OVER WESTERN TERMINALS TOWARD THE END OF THE FORECAST PERIOD AS THE BEGINNING OF OUR FIRST ARCTIC OUTBREAK OF THE SEASON STARTS. VFR CONDITIONS EXPECTED THROUGH FRIDAY. && .MARINE... .NEAR TERM /THROUGH TONIGHT/... AS OF 3 PM MONDAY...LATEST OBS CONTINUE SHOWING TREND OF DECREASING SEAS. FRYING PAN BUOY NOW SHOWING JUST UNDER 4 FT. MODELS INDICATE THE FRONTAL BOUNDARY BUCKLING AND GETTING PULLED BACK OVER THE COASTAL WATERS TOWARD THE COAST TONIGHT WITH A WEAK SFC WAVE MOVING ALONG IT. HAVE INDICATED AN INCREASE IN WINDS AND RESULTING SEAS AS A RESULT...BUT KEPT REDUCED VSBY FROM PCPN JUST OFFSHORE. SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/... AS OF 3 PM MONDAY...MODELS INDICATING THE STRONGEST INTRUSION OF DRY AND COLD AIR TO OCCUR 06Z-12Z WED. EXPECT THE ONSET OF SMALL CRAFT ADVISORY CONDITIONS TO DEVELOP BY LATE MORNING TUE AND PERSIST THROUGH AT LEAST WED EVE. THERE MAY BE A PERIOD OF GALE FORCE WINDS OVERNIGHT TUE INTO WED MORNING. EVEN IF WINDS ARE NOT SUSTAINED TO GALE FORCE...WINDS WILL GUST WELL ABOVE GALE WARNING THRESHOLDS. SEAS WILL BUILD AS HIGH AS 6 TO 9 FT...WITH NEAR SHORE SEAS LOWER GIVEN THE OFFSHORE FLOW. LONG TERM/WEDNESDAY THROUGH FRIDAY/... AS OF 3 PM MONDAY...STRONG OFFSHORE WINDS WILL BE DECREASING AT THE START OF THE PERIOD...THOUGH SCA MAY NEED TO BE EXTENDED INTO THE LATER PART OF THU MORNING. WINDS SHOULD FALL BELOW 25 KT BY MIDDAY AS PRESSURE GRADIENT RELAXES. WINDS WILL REMAIN NRLY THROUGH MUCH OF THE PERIOD AS SURFACE HIGH BUILDS IN FROM THE W. E TO SE WINDS DEVELOP SAT AS CENTER OF HIGH MOVES OFF THE COAST. SPEEDS WILL REMAIN 15 KT OR LESS FROM THU AFTERNOON ON AND SEAS WILL FALL FROM 3 TO 5 FT THU MORNING TO 2 TO 4 FT THU NIGHT THROUGH SAT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM TUESDAY TO 6 PM EST WEDNESDAY FOR AMZ250-252-254-256. && $$ NEAR TERM...RGZ SHORT TERM...RJD LONG TERM...TRL AVIATION...DL nc