AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 407 AM MST SUN JAN 20 2008 .SHORT TERM... (TODAY AND TONIGHT) CURRENTLY...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED THE NEXT AREA OF LOW PRESSURE CONTINUING TO DIG OVER THE PACIFIC NORTHWEST. 08Z/20 MSAS WIND/POTENTIAL TEMPERATURE ANALYSIS HAD THE FRONTAL BOUNDARY WELL TO THE NORTH AND EAST OF SOUTHERN CO EARLY THIS MORNING. COLD AIR CONTINUES TO BE TRAPPED IN THE LOWER ELEVATIONS/VALLEYS. THE "BANANA-BELT"...INVERSION AREA...HAD TEMPERATURES IN THE 20S/30S BETWEEN 6K-9K FT MSL LAYER ALONG AND WEST OF I-25 CORRIDOR JUXTAPOSED WITH SINGLE DIGITS IN VALLEYS. ANY "SIGNIFICANT" WINDS ARE AROUND MOUNTAIN TOP LEVEL AND ALONG THE RATON MESA INTO FAR SOUTHEAST CO. SOME PERSISTENT SCT-BKN MOUNTAIN WAVE CI/CS HAS BEEN OVER PIKES PEAK/PALMER DIVIDE EARLY THIS MORNING. TODAY...SHOULD BE A RELATIVELY QUIET DAY. BIG TEMPERATURE FORECAST CHALLENGES...ESPECIALLY THE LOWER ELEVATIONS. MODERATE WESTERLY (CHINOOK) FLOW ALOFT SHOULD PERSIST OVER THE CENTRAL ROCKIES. THE HIGHER ELEVATIONS SHOULD SEE BRISK/WINDY CONDITIONS. THE GREATEST HIGH TEMPERATURE CHALLENGE WILL BE IN THE LOWER AR RIVER AND SAN LUIS VALLEYS. IF THE WIND CANNOT PICK UP...THEN THE SHALLOW COLD AIR COULD REMAIN TRAPPED. MODERATELY UNSTABLE MIDLEVEL LAPSE RATES COULD LEAD TO A LITTLE MORE MIXING BY THIS AFTERNOON. 06Z/20 12KM NAM-WRF WANTS TO KEEP THE LOW LEVEL COLD AIR WEDGED INTO THE VALLEY AS RELATIVELY LIGHT EAST-SOUTHEAST WINDS DEVELOP FROM LHX-LAA. HIGHS APPROACHING 40F MIGHT BE A STRETCH IN THIS AREA THIS AFTERNOON. EXTREMELY TOUGH CALL FOR THE SAN LUIS VALLEY CENTER FLOOR... ALAMOSA...THIS AFTERNOON. CURRENT FORECAST LOOKS CLOSE. ANY PRECIPITATION CHANGES WOULD BE VERY LOW AND AROUND THE CENTRAL MOUNTAINS CONTINENTAL DIVIDE REGION. TONIGHT...WHEN WILL THE COLD FRONT RACE ACROSS EASTERN CO IS THE BIGGEST QUESTION. THE LATEST 12KM NAM-WRF...13KM RUC...AND GFS WANT TO HOLD OFF THE FRONTAL BOUNDARY MOVING ACROSS EAST CENTRAL AND SOUTHEAST CO UNTIL MONDAY MORNING. THIS FRONTAL BOUNDARY WILL BE VERY SHALLOW...SURFACE-800MB...GIVEN THE RELATIVELY DEEP WEST-SOUTHWEST FLOW AT 750MB AND ABOVE. I GUESS THERE IS A CHANCE THE COLD FRONT/CP AIR MASS COULD "WEDGE" DOWN THE CO FRONT RANGE DURING THE NIGHT...TOUCH CALL. AS FOR PRECIPITATION...THERE COULD BE A CHANCE...MAINLY ACROSS THE CENTRAL MOUNTAINS...NEAR THE RELATIVELY DEEPER MOISTURE LAYER...BUT FURTHER SOUTH ACROSS SOUTHERN CO...THE 700-300MB LAYER IS MUCH DRIER IN THE SOUTHWEST FLOW. FOR THE I-25 CORRIDOR AND SOUTHEAST CO PLAINS...ANY PRECIPITATION CHANCES ALL DEPEND ON WHERE THE SHALLOW FRONTAL BOUNDARY LIES. ALSO...THE MOISTURE LAYER WILL BE SO SHALLOW AND JUXTAPOSED WITH MUCH DRIER AIR ALOFT...SO ANY POTENTIAL FOR "SEEDER-FEEDER" PRECIPITATION FROM ALOFT WILL BE EXTREMELY LIMITED. DEPENDING ON THE SURFACE TEMPERATURE...THERE COULD BE THE POTENTIAL FOR SOME VERY LIGHT SNOW...FREEZING DRIZZLE...OR DRIZZLE (AND FOG) DIRECTLY BEHIND THE FRONTAL BOUNDARY. IF THE SURFACE WINDS ARE NORTH-NORTHEASTERLY... THEN ANY PRECIPITATION CHANCE WOULD BE ALONG THE PALMER DIVIDE HIGHER TERRAIN OVER TO LIMON. ALONG AND JUST NORTH OF HIGHWAY 50 ACROSS THE SOUTHEAST CO PLAINS...NORTHERLY WINDS ARE A DOWNSLOPE COMPONENT. THERE IS SOME 900MB-700MB FRONTOGENETICAL(IMPLIED LIFT) FORCING JUST BEHIND THE FRONT TO POSSIBLY SQUEEZE OUT SOME PRECIPITATION...BUT AGAIN...JUST ABOVE THIS SHALLOW COLD/MOIST LAYER SHOULD BE MUCH DRIER AIR. METZE .LONG TERM... (MONDAY THROUGH SATURDAY) PRIMARY METEOROLOGICAL CHALLENGES FOR THE LONG TERM INCLUDE BELOW SEASONAL TEMPERATURES CONTINUING AT LEAST UNTIL THURSDAY MORNING AND GENERALLY LOW GRADE POPS AT TIMES...ESPECIALLY OVER THE WESTERN HIGHER TERRAIN REGION FROM LATER THURSDAY INTO SATURDAY. OVERALL...LATEST LONGER TERM MODELS CONTINUE TO BACK OFF ON WIDESPREAD PRECIPITATION POTENTIAL OVER EASTERN SECTIONS...ESPECIALLY FROM TUESDAY INTO SATURDAY AS ZONAL TO UPPER RIDGING FLOW NOTED OVER CWFA FROM MONDAY INTO THURSDAY AND THEN MOIST SOUTHWEST TO ZONAL FLOW ALOFT DEVELOPS FROM LATER THURSDAY INTO SATURDAY. THIS MOIST FLOW SHOULD ENHANCE PRECIPITATION CHANCES OVER THE CENTRAL AND WESTERN MOUNTAINS FROM LATER THURSDAY INTO SATURDAY. IN ADDITION...GUSTY WINDS MAY BECOME AN ISSUE FROM THURSDAY NIGHT INTO SATURDAY. FINALLY...TEMPERATURES PROJECTED TO CONTINUE TO RUN BELOW CLIMATOLOGICAL AVERAGES FROM MONDAY INTO AT LEAST THURSDAY MORNING WITH INDICATIONS THAT TEMPERATURES MAY ATTEMPT TO REBOUND BY LATE WEEK. && .AVIATION... PER SHORT TERM DISCUSSION...VFR CONDITIONS WILL BE LIKELY AT ALS AND PUB THROUGH 12Z/21. VFR CONDITIONS ARE ANTICIPATED FOR COS WITH A COLD FRONTAL PASSAGE BETWEEN 09Z/21-12Z/21. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 833 PM EST SUN JAN 20 2008 .SYNOPSIS... AN ARCTIC AIR MASS WILL CONTINUE TO IMPACT UPSTATE NEW YORK AND NEW ENGLAND OVERNIGHT. PERIODS OF HEAVY LAKE EFFECT SNOW SHOWERS DOWNWIND OF LAKE ONTARIO WILL OCCUR THROUGH MONDAY MORNING. HIGH PRESSURE WILL BUILD IN FROM THE MIDWEST TO THE ATLANTIC SEABOARD THROUGH MONDAY. A WEATHER DISTURBANCE WILL MOVE FROM THE EASTERN GREAT LAKES THROUGH THE SAINT LAWRENCE VALLEY ON TUESDAY...WITH ANOTHER WEAK DISTURBANCE WEDNESDAY NIGHT. THESE DISTURBANCES WILL BE FOLLOWED BY A REINFORCING SHOT OF ARCTIC AIR FOR THURSDAY AND FRIDAY. && .NEAR TERM /UNTIL 6 AM THIS MONDAY/... THE LATEST 13KM RUC SHOWS A 500 MB SHORT WAVE MOVING ACROSS LAKE ONTARIO. THIS SHORT WAVE IS HAS SHIFTED THE SINGLE LAKE EFFECT BAND SOUTHWARD OVER THE PAST 3 HOURS WITH MORE OF A 290 DEGREE TRAJECTORY. THE LOCAL RADARS SHOW THE BAND BEING DISRUPTED...AND ITS DOWNSTREAM EXTENSION INTO HERKIMER AND WRN HAMILTON COUNTIES HAS WEAKENED A BIT. HOWEVER...THE LATEST NAM12 AND BUFKIT PROFILES DO SHOW THE BAND REINTENSIFYING AND LIFTING BACK NORTH BETWEEN RTE 29 AND RTE 8 IN HERKIMER COUNTIES MONDAY MORNING. IT MAY EVEN GET AS FAR NORTH AT RT 28 AND OLD FORGE BY DAYBREAK. WE ADJUSTED HOURLY DEWPOINTS IN THE GRIDS BASED ON OBSERVATIONS. THE DEWPOINTS ARE GENERALLY 0 TO 5 BELOW. THE DRY AIR MASS IS PREVENTING THE LAKE BAND SNOWS GETTING TO FAR DOWN THE MOHAWK RIVER VALLEY. WE DID PLACE A SLIGHT CHANCE OF SNOW SHOWERS INTO THE CAPITAL REGION PRIOR TO MIDNIGHT...AND KEPT FLURRIES IN THE CAPITAL REGION AFTER MIDNIGHT. WE ALSO RAISED POPS TO HIGH CHANCE AND LOW LIKELY VALUES FOR THE SRN GREEN MTNS...DUE TO THE FAVORABLE 270-290 DEGREE LOW LEVEL TRAJECTORY. THE FLOW WILL BACK BETWEEN 06Z-12Z WITH THE BAND LIFTING BACK TO THE NORTH IN THE EXTREME INSTABILITY...AND THE INVERSION HEIGHTS AROUND 10 KFT. GROUND TRUTH INDICATES ABOUT 2 TO 6 INCHES HAVE FALLEN THUS FAR. AS A RESULT...WE HAVE KEPT THE SNOWFALL TOTALS THE SAME...6-12 INCHES IN HERKIMER COUNTY AND 5 TO 10 IN HAMILTON COUNTY. THE WINDS HAVE DECREASED TO AROUND 10 KTS...AND APPARENT TEMP HOURLY GRIDS STILL YIELD WIND CHILLS BELOW ADVISORY THRESHOLD. WE EXPECT THE WINDS TO BRIEFLY INCREASE WITH THE SHORT WAVE PASSAGE...BUT THEN BEGIN TO SUBSIDE WITH SFC HIGH PRESSURE NOSING IN FROM THE SOUTH AND WEST. && .SHORT TERM /6 AM MONDAY THROUGH TUESDAY NIGHT/... LAKE EFFECT SNOW BAND WILL STILL BE OVER THE WARNED AREAS DURING THE MORNING...BUT DURING THE AFTERNOON AS WINDS THROUGH THE BOUNDARY LAYER WEAKEN AND SHIFT TO A MORE SOUTHWEST TYPE FLOW...THE SNOW BAND WILL GRADUALLY WEAKEN AND RETREAT NORTHWARD. HIGHS MONDAY WILL BE IN THE TEENS NORTH TO LOWER/MID 20S SOUTH. CLOUD COVER SHOULD BE LARGELY CONFINED TO AREAS DOWNWIND OF THE LAKE. SURFACE HIGH WILL PASS OUT TO SEA OFF THE MID ATLANTIC STATES MONDAY NIGHT. THIS WILL ALLOW A SOUTHERLY FLOW TO DEVELOP ACROSS THE REGION...SO TEMPS NOT EXPECTED TO DROP THAT MUCH. LOWS MONDAY NIGHT HAVE GENERALLY BEEN FORECAST BETWEEN 5 AND 10 DEGREES. THE LOWS MONDAY NIGHT MAY OCCUR EARLY DURING THE NIGHT IN MANY LOCATIONS... ESPECIALLY HIGHER TERRAIN LOCATIONS. CLOUDS AHEAD OF THE NEXT SYSTEM ARE LIKELY TO BEGIN TO OVERSPREAD THE REGION LATE AT NIGHT. TUESDAY AND TUESDAY NIGHT...NORTHERN STREAM ENERGY TRACKS ACROSS THE REGION. SYSTEM RELATIVELY MOISTURE-STARVED...BUT GREAT LAKES MOISTURE WILL GET ENTRAINED. STRONG SOUTHWESTERLY BOUNDARY LAYER FLOW WILL SET UP...INCREASING THE ISENTROPIC LIFT AND FRONTOGENESIS. EVEN THOUGH OVERCAST WITH LIGHT SNOW LIKELY...SOUTH/SOUTHWEST SURFACE WINDS AND SOME MIXING SHOULD GET TEMPERATURES INTO THE 20S TO AROUND 30. SNOW EXITS BY TUESDAY EVENING WITH NO MORE THAN ABOUT TWO INCHES EXPECTED...AND SOMEWHAT COLDER AIR BEGINS TO WORK BACK INTO THE REGION LATER TUESDAY NIGHT. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... MAINLY DRY BUT COLD WEATHER EXPECTED FOR MUCH OF THE EXTENDED FORECAST PERIOD AS NORTHERN STREAM DOMINATES OUR WEATHER... THUS ONLY WEAK CLIPPER TYPE SYSTEMS AND SOME LAKE EFFECT TO DEAL WITH AS NO INTERACTION WITH THE SOUTHERN STREAM EXPECTED. WED LOOKS MAINLY DRY...EXCEPT FOR SOME LAKE EFFECT ACTIVITY ACROSS THE WESTERN ADIRONDACKS WHICH WILL LINGER INTO WEDNESDAY EVENING. NEXT CLIPPER WILL MOVE FROM THE UPPER GREAT LAKES THROUGH THE REGION WEDNESDAY NIGHT...BRINGING A CHANCE OF LIGHT SNOW. VERY LITTLE QPF WITH SYSTEM AND SYSTEM DOES NOT DEEPEN UNTIL IT IS WELL NORTHEAST OF FA IN CANADIAN MARITIMES ON THURSDAY. IN WAKE OF THE CLIPPER...ANOTHER PUSH OF ARCTIC AIR WILL BE MOVING IN FOR THURSDAY AND FRIDAY. FLOW DIRECTION APPEARS TO BE N-NW...SO LAKE EFFECT ACTIVITY EXPECTED TO REMAIN WEST OF FA FOR MOST OF THIS PERIOD. A RIDGE OF HIGH PRESSURE WILL START TO BUILD ACROSS THE REGION THURSDAY NIGHT INTO FRIDAY AND WITH COLD AIR ADVECTION AND STILL ENOUGH OF A GRADIENT TO PRODUCE SOME LOW WIND CHILL VALUES THURSDAY NIGHT INTO FRIDAY MORNING AND AGAIN FRIDAY NIGHT INTO SATURDAY MORNING. AT THIS POINT WILL JUST INCLUDE A MENTION OF HAZARDOUS WIND CHILL POSSIBLE LATE IN THE WEEK IN THE HWO AS EXACT TIMING OF CONDITIONS IS STILL UNCERTAIN AT THIS POINT. FOR NEXT WEEKEND THE RIDGE AXIS SHIFTS EAST OF THE AREA ON SATURDAY AS ANOTHER CLIPPER TYPE SYSTEM MOVES ACROSS SOUTHERN CANADA...AND A SOUTHWEST FLOW DEVELOPS. THIS SHOULD HELP BOOST TEMPS BACK TO MORE SEASONABLE LEVELS AND BRING A CHANCE OF SNOW TO THE FA SATURDAY AFTERNOON INTO SUNDAY. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... HIGH PRESSURE WILL CONTINUE TO BUILD IN FROM THE SOUTH AND WEST FROM THE OH VALLEY. VFR CONDITIONS WILL PREVAIL THE NEXT 24 HOURS FOR KGFL/KALB/KPOU. LAKE EFFECT SNOWS WILL CONTINUE WEST OF THE HUDSON RIVER VALLEY. SCT-BKN CLOUDINESS 5-6 KFT MAY OCCUR AT KGFL SOUTH TO KALB WITH A LAKE BAND SAGGING SOUTH FROM LAKE ONTARIO PRIOR TO 06Z. THE WINDS WILL SUBSIDE A BIT TO AROUND 10 KTS FROM THE W/SW PRIOR TO 05Z. AFTER MIDNIGHT...EXPECT THE WINDS TO LESSEN TO 5-10 KTS FROM THE W/SW. AFTER 13Z...SCT-BKN STRATOCUMULUS WILL RETURN WITH CIGS IN THE 4-6 KFT RANGE. WE PLACED A VCSH FOR KGFL 13Z-18Z WITH THE LAKE BAND LIFTING NORTHWARD INTO THE ADIRONDACK REGION BEFORE DISSIPATING. THE WINDS WILL BE GENERALLY FROM THE W/SW AT 10-15 KTS WITH A FEW GUSTS AT KALB CLOSE TO 25 KTS. OUTLOOK... TUE...MVFR/IFR...CHANCE OF WIDESPREAD SNOW...LOW CIGS AND VSBY. WED...MVFR/IFR EARLY AM...LOW CIGS/VSBY AND CHANCE OF LINGERING SHSN. THU...VFR/MVFR...CHANCE OF -SHSN. FRI...VFR...NO SIG WX. && .HYDROLOGY... NO HYDRO PROBLEMS ANTICIPATED FOR THE NEXT SEVERAL DAYS. ANY PRECIPITATION THROUGH NEXT WEEK IS EXPECTED TO BE IN THE FORM OF SNOW. SNOWPACK WILL BUILD ACROSS PORTIONS OF THE WESTERN ADIRONDACKS...WITH POTENTIALLY SIGNIFICANT LAKE EFFECT SNOWS FALLING THROUGH MONDAY. COLD AIRMASS IN PLACE WILL PERSIST THROUGH MUCH OF THE WEEK...AND WILL RESULT IN RAPID FORMATION OF ICE AGAIN ON THE MAIN STEM RIVERS IN THE HYDRO SERVICE AREA...SOME LOCATIONS ACROSS NORTHERN PORTIONS OF THE HSA MAY BUILD ICE AT A RATE CLOSE TO AN INCH A DAY. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST MONDAY FOR NYZ032-033- 038. MA...NONE. VT...NONE. && $$ SYNOPSIS...TAW/GJM NEAR TERM...TAW SHORT TERM...GJM LONG TERM...JSQ AVIATION...TAW HYDROLOGY...JSQ ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSONVILLE FL 210 PM EST SUN JAN 20 2008 ...FREEZE WARNING IN EFFECT FOR PORTIONS OF THE SUWANNEE VALLEY IN FLORIDA... .SHORT TERM...MSAS ANALYSIS SHOWS A STRONG 1040 MB HIGH HAS SETTLED OVER THE OHIO AND TENNESSEE VALLEYS WITH AREA OF INFLUENCE MUCH LARGER AND ENCOMPASSING ALL OF OUR FORECAST AREA. WINDS ON THE EASTERN HALF OF THE HIGH HAVE GENERALLY BEEN IN THE 15 TO 20 MPH RANGE WITH LIMITED GUSTS THUS FAR. THIS SHOULD KEEP US SAFELY BELOW ANY LAKE WIND CRITERIA THROUGH THIS EVENING. ALOFT...RUC ANALYSIS STILL SHOWS SOUTHWEST FLOW BETWEEN 200 MB AND 300 MB AND WATER VAPOR SHOWS SUFFICIENT MOISTURE FOR SCATTERED HIGH CLOUDS ACROSS THE AREA. TEMPERATURES HAVE BEEN SLOW TO MODERATE DESPITE PERIODS OF SUN DUE TO CONTINUED COLD AIR ADVECTION PATTERN. MOSTLY TEMPS IN THE 40S AT THIS HOUR...WELL BELOW AVERAGE FOR ANY TIME OF YEAR. MAIN FORECAST CHALLENGE TONIGHT WILL BE THE POTENTIAL FREEZE OVER INLAND SECTIONS OF NORTHEAST FLORIDA. NORMALLY...WHEN GUIDANCE INDICATES MIN TEMPS IN THE LOWER 20S...A FREEZE WARNING IS A GIVEN ACROSS THAT AREA. HOWEVER...WITH WINDS REMAINING ELEVATED PER SURFACE TO 1 KM NAM12 DEPICTION AND THE CONTINUED HIGH CLOUDINESS...FEEL MOSGUIDE IS WAY TOO LOW FOR ITS MIN TEMP TONIGHT. ALSO HAVE THE BENEFIT OF THE LAST FEW COLD AIR OUTBREAKS WHICH WERE SIMILAR IN NATURE AND THE MOSGUIDE WAS TOO COLD ON THOSE AS WELL. WILL THEREFORE GO 5 DEGREES ABOVE GUIDANCE WITH THIS PACKAGE WHICH STILL RESULTS IN FREEZE CONDITIONS OVER A PORTION OF THE SUWANNEE VALLEY BUT EXCLUDES DUVAL AND NASSAU COUNTIES ALONG THE EAST COAST. WILL ALSO BE WATCHING FOR A MARKED INCREASE IN LOW LEVEL MOISTURE AND CLOUDS ALONG THE EAST COAST TOWARDS DAYBREAK AS STRONG EASTERLY BOUNDARY LAYER WINDS TAKE HOLD. THIS ALL BEING SAID...TEMPS WILL NEED TO MONITORED CLOSELY BY THE EVENING SHIFT FOR POSSIBLE INCLUSION OF A FEW COUNTIES TO FREEZE WARNING. MAIN DIFFERENCE IN MODELS THROUGH 12Z TUE IS THE DEGREE OF SATURATION OF THE LOW LEVELS ADVERTISED BY THE MODELS. THE NAM12 IS MUCH MORE AGGRESSIVE WITH MOISTURE RETURN WITH LOW END CHANCE POPS ADVERTISED FOR THE ENTIRE SOUTHERN TIER LATE MON NIGHT. FEEL THERE WILL BE MORE COLD AIR DAMMING AND RIDGING THAN MODEL INDICATE WHICH SHOULD ALLOW FOR AN INVERTED TROUGH AND KEEP POPS CONFINED CLOSER TO THE COAST INITIALLY. MODEL DIFFERENCES CONTINUE INTO TUE EVENING AS GFS SHOWS A SIGNIFICANT MID LEVEL DRY SLOT OVER THE AREA WHILE THE NAM12 ADVERTISES AND GOOD SLUG OF MOISTURE AND MID RANGE POPS INTO THE FL PORTION. WILL USE A BLEND FOR NOW AND GO WITH LOW END SCATTERED POPS WHICH MESHES WELL WITH PREVIOUS FORECAST AND ADJACENT GRIDS. .LONG TERM...STRONG NORTHERN STREAM SHORTWAVE TO SCOUR OUT MOISTURE BY 12Z WED WITH COOLER AND DRIER CONDITIONS EXPECTED BY MIDWEEK. LAST FEW MODEL RUNS HAVE BEEN CONSISTENT IN SHOWING A STRONG SURFACE HIGH DEVELOPING OVER THE MID SECTIONS OF THE COUNTRY AND SHIFTING SOUTHWARD THROUGH THU. THIS HIGH SHOULD BUILD IN PRIOR TO SIGNIFICANT MOISTURE INCREASE TO THE WEST. THIS WILL ALLOW FOR A GENERALLY DRY AND COOL TO COLD PATTERN FOR THE END OF THE WORK WEEK. NEXT SYSTEM WILL TAKE SHAPE EARLY SAT WITH YET ANOTHER GULF LOW IN THE OFFING. && .AVIATION...GENERALLY VFR CONDITIONS WILL CONTINUE. MAY BE SOME PATCHY GROUND FOG PRIOR TO SUNRISE MON MORNING IN COASTAL NE FL COUNTIES WITH INCREASING LOW-LEVEL MOISTURE FROM THE ATLC. HOWEVER...NOT ENUF CERTAINTY TO MENTION ATTM. && .MARINE...FCST APPEARS TO BE ON TRACK. HAVE EXTENDED OFFSHORE SMALL CRAFT ADVISORY ANOTHER 6 HRS DUE TO LINGERING SWELLS THRU TUE EVENING. MAY GO AHEAD AND UPGRADE RIP CURRENT RISK TO MODERATE DUE TO BUILDING SEAS AND FLOW BECOMING MORE ONSHORE. && .FIRE WEATHER...RED FLAG WARNING SHOULD EASILY VERIFY ACROSS NE FL. SE GA WILL BE CLOSE...BUT SLOWLY RISING TEMPS AND LOWER THAN EXPECTED WINDS MAY PREVENT RED FLAG CONDITIONS. HAVE OPTED TO KEEP WARNING IN PLACE AS CRITERIA ONLY NEED TO BE MET BRIEFLY PER NEW OPERATING PLAN. LOW-LEVEL MOISTURE WILL INCREASE ACROSS THE AREA FOR MON. && .PRELIMINARY POINT TEMPS/POPS... AMG 27 54 36 66 / 0 10 10 20 SSI 37 52 47 64 / 0 10 10 30 JAX 34 54 47 69 / 0 10 20 30 SGJ 43 58 54 69 / 0 10 20 30 GNV 31 61 49 74 / 0 10 20 30 OCF 33 63 51 74 / 0 10 20 30 && .JAX WATCHES/WARNINGS/ADVISORIES... FL...RED FLAG WARNING UNTIL 7 PM THIS EVENING FOR ALACHUA-BAKER- BRADFORD-CLAY-COLUMBIA-DUVAL-FLAGLER-GILCHRIST-HAMILTON- MARION-NASSAU-PUTNAM-ST JOHNS-SUWANNEE-UNION. FREEZE WARNING FROM 2 AM TO 9 AM MON FOR ALACHUA-BAKER- BRADFORD-COLUMBIA-GILCHRIST-HAMILTON-SUWANNEE-UNION. GA...RED FLAG WARNING UNTIL 5 PM THIS AFTN FOR APPLING- ATKINSON-BACON-BRANTLEY-CHARLTON-CLINCH-COASTAL CAMDEN- COASTAL GLYNN-COFFEE-ECHOLS-INLAND CAMDEN-INLAND GLYNN-JEFF DAVIS-PIERCE-WARE-WAYNE. AM...SMALL CRAFT ADVISORY UNTIL 10 PM TUE FOR ALTAMAHA SOUND GA TO FLAGLER BEACH FL 20 NM TO 60 NM OFFSHORE. SMALL CRAFT ADVISORY UNTIL 10 PM MON FOR ALTAMAHA SOUND GA TO FLAGLER BEACH FL OUT 20 NM. && $$ DEESE/CARROLL/KEEGAN fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MELBOURNE FL 1009 AM EST SAT JAN 19 2008 .DISCUSSION...FRONT APPEARS TO BE LOCATED NEAR CAPE CANAVERAL TO TAMPA AS WARM SECTOR GRADUALLY EXPANDS NORTWARD THIS MORNING. AREAS OF FOG WITH DENSE PATCHES NOW BEGINNING TO LIFT AND BREAK UP AS VISIBILITIES CREEP UP TO ABOVE 3 MILES. EXPECT CONDITIONS TO IMPROVE SIGNIFICANTLY BETWEEN 10 AND 11 AM. HOWEVER...SLOWER TO IMPROVE ALONG THE FRONATL BOUNDARY AND JUST NORTH AS ASSOCIATED WITH ADDITIONAL MULTI-LAYERED CLOUDINESS SO A LITTLE HARDER TO GET THE MIXING THERE. LATEST PROFILER DATA SHOWS 25KT WINDS (SW) DESCENDING TO BELOW 3KFT SO EXPECT ONCE ATMOSPHERE RECOUPLES... SFC WINDS WILL BE ON THE GUSTY SIDE. LATEST RUC13 SUGGESTS THAT FRONTAL BOUNDARY WILL STRUGGLE TO LIFT MUCH FARTHER NORTH UNTIL LATER IN THE AFTERNOON BEFORE THE FULL BREATHE OF THE SOUTHERLIES ARE FELT FORECAST AREA-WIDE. THIS MAY REDUCE DIABATIC CONTRIBUTIONS EXCEPT FOR SOUTHERN COUNTIES ALREADY SOUTH OF THE FRONT DISTRIBUTING THE GREATER INSTABILITY THERE. NONETHELESS...SIGNIFICANT LOW LEVEL SHEAR INTRODUCED OVER NORTH AREA A CONCERN FOR ASSOCIATED DEEP CONVECTION MOVING IN FROM THE GULF. THIS...ALONG WITH INCREASING 850 MB WINDS...WILL KEEP A CONCERN FOR STRONG CONVECTIVE WIND GUSTS FOR A FEW MARGINALLY SEVERE STORMS THIS AFTERNOON. && .AVIATION...LIFR COND GIVING WAY TO IFR TO EVENTUAL MVFR BY 17Z...ESPECIALLY TPA TO MLB NORTHWARD. WINDS ABOVE THE SURFACE ARE INCREASING TO 20-25 KT AROUND 15KFT BEAR WATCHING FOR SFC WIND GUSTS TO COMPARABLE SPEEDS AS THE DAY WEARS. && .MARINE...FORECAST APPEARS ON TRACK. UPDATES NOT EXPECTED. SEE PREVIOUS DISCUSSION. && .PRELIMINARY POINT TEMPS/POPS... DAB 74 44 55 44 / 60 70 0 0 MCO 78 48 58 44 / 60 70 0 0 MLB 81 52 59 52 / 40 60 0 0 VRB 85 56 62 53 / 40 60 10 10 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...FIRE WEATHER WATCH SUNDAY AFTERNOON FOR INLAND VOLUSIA-NORTHERN LAKE-ORANGE-SEMINOLE-SOUTHERN LAKE. AM...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 5 PM EST MONDAY FOR COASTAL WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE OUT 20 NM-COASTAL WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET OUT 20 NM. SMALL CRAFT ADVISORY UNTIL 5 PM EST MONDAY FOR COASTAL WATERS FROM SEBASTIAN INLET TO JUPITER INLET OUT 20 NM-WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM OFFSHORE-WATERS FROM SEBASTIAN INLET TO JUPITER INLET 20 TO 60 NM OFFSHORE-WATERS FROM VOLUSIA BREVARD COUNTY LINE TO SEBASTIAN INLET 20 TO 60 NM OFFSHORE. && $$ SHORT TERM...DW LONG TERM....RL AVIATION...99 fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 1218 AM EST SUN JAN 20 2008 .SYNOPSIS... LOW PRESSURE WILL MOVE NORTHEASTWARD ALONG THE CAROLINA COAST TONIGHT...AND BE WELL NORTHEAST OF THE AREA SUNDAY. HIGH PRESSURE WILL MOVE INTO THE REGION SUNDAY WITH MOSTLY SUNNY SKIES AND LIGHT WINDS. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... PRECIPITATION IS COMING TO AN END ACROSS THE REGION AS THE SURFACE LOW IS LIFTING OFF THE FLORIDA COAST AND AN ARCTIC COLD FRONT APPROACHES FROM THE NORTHWEST. THROUGH MIDNIGHT THERE MAY BE AREAS OF FLURRIES NORTH OF I-20 WITH SPRINKLES OR ISOLATED RAIN SHOWERS SOUTH OF THIS LINE. THERE WERE SOME REPORTS OF A LIGHT DUSTING IN THE ADVISORY AREA BUT NO ADDITIONAL ACCUMULATION IS EXPECTED AND HAVE ALLOWED THE ADVISORY TO EXPIRE. BACK EDGE OF THE CLEARING LINE RAPIDLY APPROACHING THE UPSTATE AND SHOULD ARRIVE IN THE MIDLANDS BETWEEN 06Z-08Z...FOLLOWED BY MODERATE COLD ADVECTION AS THE SURFACE FRONT PUSHES THROUGH. CONSIDERED THE POSSIBILITY OF NEEDING A SPECIAL WEATHER STATEMENT FOR REFREEZING OF WATER ON ROADWAYS BUT THE SLOW ARRIVAL OF THE SUBFREEZING AIR AND RELATIVELY WARM GROUND SURFACES AS NOTED BY SC DOT OBSERVATIONS...AND A PERSISTENT WIND OVERNIGHT...LED US TO REFRAIN FROM ISSUING ANYTHING. GRIDDED DATABASE HAS BEEN UPDATED AND SENT TO NDFD WITH LITTLE CHANGES TO GRIDS OTHER THAN POPS AND WEATHER AND HOURLY TEMPERATURES TO ACCOUNT FOR LATEST TRENDS. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM MONDAY/... LOW PRESSURE WILL CONTINUE TO TRACK FURTHER INTO THE ATLANTIC BASIN AS HIGH PRESSURE BUILDS IN FROM THE WEST. NORTHWEST WINDS THROUGH THE DAY WILL USHER IN COOLER AND DRIER AIR WITH MOSTLY SUNNY SKIES THROUGH THE DAY. TEMPERATURES WILL REBOUND SLIGHTLY DURING THE DAY DUE TO THE SUNSHINE...HOWEVER SUNDAY NIGHT WITH CLEAR SKIES AND DRY AIR OVER THE REGION TEMPERATURES WILL DROP INTO THE UPPER TEENS TO LOWER 20S. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... MONDAY APPEARS TO REMAIN DRY. NEXT WEATHER MAKER WILL ARRIVE ON TUESDAY. THIS WILL BEGIN A RATHER ACTIVE WEATHER PERIOD FROM TUESDAY THROUGH SATURDAY...WITH TWO OR THREE SYSTEMS MOVING THROUGH THE REGION DURING THAT TIME FRAME. TEMPERATURES DURING THE LONG TERM PERIOD APPEAR TO REMAIN WARM ENOUGH SO THAT EACH EVENT WILL BE ALL RAIN. TEMPERATURES EXPECTED TO REMAIN AT OR BELOW CLIMATE NORMALS THROUGH THE PERIOD. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... DRYING WILL OCCUR AS LOW PRESSURE MOVES AWAY FROM THE AREA. EXPECT MAINLY IFR CEILINGS EARLY IN THE TAF PERIOD BUT VFR CONDITIONS SHOULD DEVELOP BY 09Z. BASED THIS FORECAST ON THE LATEST RUC SHOWING MOISTURE BECOMING VERY SHALLOW PLUS MIXING ASSOCIATED WITH HIGH PRESSURE BUILDING INTO THE REGION. SATELLITE TRENDS SUPPORT THIS FORECAST. THE DRY AIR MASS MOVING INTO THE REGION WILL DOMINATE THROUGH THE REST OF THE TAF PERIOD. NO SIGNIFICANT IMPACTS EXPECTED DURING THE EXTENDED PERIOD. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1257 AM EST SUN JAN 20 2008 .AVIATION... LAKE EFFECT SNOW IS STILL MOVING THROUGH SBN. CONDITIONS THERE SHOULD REMAIN LOW AS THE SNOW CONTINUES THROUGH THE NIGHT. THE LAKE EFFECT SNOW IS EXPECTED TO END BY LATE MORNING WITH CLOUDS SCATTERING OUT BY THE AFTERNOON. VFR CONDITIONS WILL THEN PREVAIL THROUGH THE AFTERNOON INTO THE EVENING HOURS. THE PRESSURE GRADIENT WILL WEAKEN TOWARDS LATE AFTERNOON/EARLY EVENING HOURS ALLOWING THE WIND TO DECREASE IN SPEED. FWA WILL BE VFR FOR THIS ENTIRE TAF PERIOD. JUST SOME MID LEVEL CLOUDS TOWARDS THE END OF THIS TAF PERIOD FOR BOTH SITES WITH SOME MID LEVEL MOISTURE MOVING INTO THE AREA. && .UPDATE... /ISSUED 808 PM EST SAT JAN 19 2008/ HAVE MADE SOME SIGNIFICANT CHANGES THIS PERIOD...WITH REPORTS FROM OBSERVERS ACROSS THE PREFERRED LAKE EFFECT REGION IT IS FAIRLY OBVIOUS THAT WE ARE FALLING SHORT OF THE CRITERIA FOR THE LAKE EFFECT ADVISORY. HAVE ENDED IT...AND EXTENDED THE WIND CHILL ADVISORY FOR THE OVERNIGHT HOURS INTO THOSE COUNTIES. HAVE SLIGHTLY LOWERED TEMPS SOME. OMEGAS CONTINUE THROUGH THE NIGHT OFF THE LAKE...BUT THE VERY DRY ARCTIC AIR HAS LIMITED THE MOISTURE AND THE AMOUNTS. THOUGH LIGHT SNOW WILL CONTINUE ACROSS THE NORTHWESTERN PORTIONS OF THE AREA...AMOUNTS WILL BE WELL LESS THAN 3 INCHES IN THE NEXT 12 HOURS...AND THEREFORE ALLOWING THE CANCELING OF THE ADVISORY. ROADS WILL STILL BE DIFFICULT TO TRAVEL IN SPOTS WITH THE SNOWFALL...BUT THE SNOW SHOULD BE FAIRLY POWDERY AND BLOWING AND DRIFTING SOME WITH THE 10-15KT WINDS LIKELY THRU MUCH OF THE NIGHT. && .PREV DISCUSSION... /ISSUED 459 PM EST SAT JAN 19 2008/ SHORT TERM...TONIGHT AND TOMORROW. ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION... COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM PACKAGE MAINLY TO GFS AND RUC 13. TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400 J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION HEIGHTS RAPIDLY FALL AND SUBSTANTIALLY DRY AIR ADVECTS INTO THE REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING. HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF 15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL. ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15 TO 25 BELOW ZERO. LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE REGION. LONG TERM...SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENESIS DY2. FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG 1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ THIS MORNING FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR MIZ077>081. OH...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR OHZ001-002- 004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LMZ043-046. FREEZING SPRAY ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR LMZ043-046. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...MURPHY AVIATION...LOTHAMER UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 808 PM EST SAT JAN 19 2008 .EVENING UPDATE... HAVE MADE SOME SIGNIFICANT CHANGES THIS PERIOD...WITH REPORTS FROM OBSERVERS ACROSS THE PREFERRED LAKE EFFECT REGION IT IS FAIRLY OBVIOUS THAT WE ARE FALLING SHORT OF THE CRITERIA FOR THE LAKE EFFECT ADVISORY. HAVE ENDED IT...AND EXTENDED THE WIND CHILL ADVISORY FOR THE OVERNIGHT HOURS INTO THOSE COUNTIES. HAVE SLIGHTLY LOWERED TEMPS SOME. OMEGAS CONTINUE THROUGH THE NIGHT OFF THE LAKE...BUT THE VERY DRY ARCTIC AIR HAS LIMITED THE MOISTURE AND THE AMOUNTS. THOUGH LIGHT SNOW WILL CONTINUE ACROSS THE NORTHWESTERN PORTIONS OF THE AREA...AMOUNTS WILL BE WELL LESS THAN 3 INCHES IN THE NEXT 12 HOURS...AND THEREFORE ALLOWING THE CANCELING OF THE ADVISORY. ROADS WILL STILL BE DIFFICULT TO TRAVEL IN SPOTS WITH THE SNOWFALL...BUT THE SNOW SHOULD BE FAIRLY POWDERY AND BLOWING AND DRIFTING SOME WITH THE 10-15KT WINDS LIKELY THRU MUCH OF THE NIGHT. && .PREV DISCUSSION... /ISSUED 621 PM EST SAT JAN 19 2008/ AVIATION (00Z TAFS)... THE MAJORITY OF THE REGION WILL REMAIN UNDER VFR CONDITIONS...AREAS AROUND LAKE MICHIGAN TOWARDS NORTHWEST OHIO WILL SEE OCCASIONAL LIGHT SNOW SHOWERS THAT MAY DROP VSBYS TO AROUND 1 TO 2 SM AND MARGINAL MVFR CIGS AROUND 2.5 K FT. WESTERLY WINDS WILL CONTINUE THRU THE PERIOD. THE LAKE EFFECT CLOUDS AND SNOW WILL LESSEN OVERNIGHT INTO SUNDAY MORNING WITH THE ENTIRE AREA BECOMING VFR BY AFTERNOON. PREV DISCUSSION... /ISSUED 459 PM EST SAT JAN 19 2008/ SHORT TERM... .ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION... COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM PACKAGE MAINLY TO GFS AND RUC 13. TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400 J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION HEIGHTS RAPIDLY FALL AND SUBSTANTIALLY DRY AIR ADVECTS INTO THE REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING. HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF 15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL. ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15 TO 25 BELOW ZERO. LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE REGION. LONG TERM... SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENESIS DY2. FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG 1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ SUNDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>081. OH...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST SUNDAY FOR LMZ043-046. FREEZING SPRAY ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...MURPHY UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 621 PM EST SAT JAN 19 2008 .AVIATION (00Z TAFS)... THE MAJORITY OF THE REGION WILL REMAIN UNDER VFR CONDITIONS...AREAS AROUND LAKE MICHIGAN TOWARDS NORTHWEST OHIO WILL SEE OCCASIONAL LIGHT SNOW SHOWERS THAT MAY DROP VSBYS TO AROUND 1 TO 2 SM AND MARGINAL MVFR CIGS AROUND 2.5 K FT. WESTERLY WINDS WILL CONTINUE THRU THE PERIOD. THE LAKE EFFECT CLOUDS AND SNOW WILL LESSEN OVERNIGHT INTO SUNDAY MORNING WITH THE ENTIRE AREA BECOMING VFR BY AFTERNOON. && .PREV DISCUSSION... /ISSUED 459 PM EST SAT JAN 19 2008/ SHORT TERM... ..ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION... COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM PACKAGE MAINLY TO GFS AND RUC 13. TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400 J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION HEIGHTS RAPIDLY FALL AND SUBSTANTIALLY DRY AIR ADVECTS INTO THE REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING. HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF 15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL. ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15 TO 25 BELOW ZERO. LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE REGION. LONG TERM... SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENESIS DY2. FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG 1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ SUNDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ080-081. WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>079. OH...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST SUNDAY FOR LMZ043-046. FREEZING SPRAY ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...MURPHY AVIATION...SCHOTT in AREA FORECAST DISCUSSION...DELAYED NATIONAL WEATHER SERVICE NORTHERN INDIANA 459 PM EST SAT JAN 19 2008 .SHORT TERM... ...ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION... COLD ARCTIC AIR IN PLACE WILL CONTINUE TO SUPPORT LAKE EFFECT SNOW SHOWERS TONIGHT. SATELLITE/RADAR/AND SFC OBS CONFIRM LAKE SNOWS CONTINUING ACROSS PORTIONS OF NORTHERN IN AND SOUTHERN MI. FARTHER AWAY FROM THE LAKE...LAKE MODIFIED AIRMASS IN PLACE HAS SUPPORTED THE DEVELOPMENT OF DIURNAL CU AND LIGHT SNOW FROM AREAS EAST OF A WARSAW-HILLSDALE LINE. FORECAST MODELS HAVE A GOOD HANDLE OF THE AIR MASS IN PLACE...WITH THE GFS DISPLAYING A SLIGHTLY BETTER HANDLE OF BAROCLINIC ZONES AND H925 TEMPS. HAVE TAILORED THE SHORT TERM PACKAGE MAINLY TO GFS AND RUC 13. TONIGHT...WEAK SHORTWAVE TROUGH OVER PORTIONS OF IA WILL SWING INTO THE REGION AND FORCING WEAK LARGE SCALE ASCENT...SUPPORTING A BRIEF RAISE IN INVERSION HEIGHTS OVER THE LAKE. THIS COMBINED WITH ONGOING CAA WILL SUPPORT LAKE INDUCED CAPES OF AROUND 400 J/KG...MAINLY THIS EVENING AND EARLY MORNING...BEFORE INVERSION HEIGHTS RAPIDLY FALL AND SUBSTANTIALY DRY AIR ADVECTS INTO THE REGION AROUND H925-H850. GIVEN DRY AIR IN PLACE...EXTREMELY COLD AIRMASS WITH SMALL CRYSTAL FORMATION FAVORED...AND 290 DEGREE FETCH...EXPECTING SNOW ACCUMS TO BE ON THE LIGHT SIDE OF 1-3 INCHES WITH LOCALLY HEAVIER AMOUNTS UP TO 4 INCHES INTO SUNDAY MORNING. HAVE ALLOWED THE WINTER WEATHER ADVISORY TO CONTINUE GIVEN SNOW ACCUMS...BRISK WINDS OF 15 TO 25 CREATING DANGEROUS WIND CHILLS OF 15 TO 20 BELOW...AND BLOWING/DRIFTING SNOW POTENTIAL. ELSEWHERE AWAY FROM THE LAKE...EXPECT A BITTER COLD NIGHT WITH MOSTLY CLEAR SKIES AND COLD TEMPS. EXPECTED LOWS OF ZERO TO 5 BELOW AND WINDS OF 15 TO 25 MPH WILL SUPPORT DANGEROUS WIND CHILLS OF 15 TO 25 BELOW ZERO. LOOK FOR ANOTHER COLD DAY TOMORROW WITH HIGHS STILL STRUGGLING TO RISE OUT OF THE SINGLE DIGITS. LAKE SNOW WILL WAIN IN THE NORTH WITH INCREASING INVERSION HEIGHTS AND DRY AIR ADVECTING INTO THE REGION. && .LONG TERM... SUNDAY NIGHT THROUGH SATURDAY. PRIMARY FOCUS ON LARGE INCREASE IN POPS MONDAY NIGHT/TUE AS NAM/GFS CONSISTENT ON BREAKAWAY JAMES BAY TROF /FROM BRITISH COLUMBIA CUTOFF/ AIDING PLAINS CYCLOGENISIS DY2. FAVOR SLIGHTLY GFS FASTER/FURTHER SOUTH SOLN GIVEN ARCTIC HIGH PUSH INTO WRN TN/FAR SOUTH INITIAL BAROCLINIC ZONE. BEST 7H HGT FALLS WELL NORTH THROUGH CENTRAL MICHIGAN WITH TONGUE OF 2-2.5 G/KG 1000-850 MB MIXING RATIOS ADVECTING NORTHEAST AHEAD OF FNT WITH NEAR 3 G/KG FAR SRN CWA. RAISED POPS SUBSTANTIALLY TO CATEGORICAL MONDAY NIGHT FAR NORTH WHERE BEST DYNAMICS LIFT/DGZ THERMALS EXIST AND LIKELY POPS SOUTH IN RICHER LLVL MOISTURE. FEW CHNGS LTR PDS. && .AVIATION.../18Z TAFS/ COLD ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD INTO THE REGION TODAY...SUPPORTING LAKE SNOWS OVER NORTHERN PORTIONS OF THE FA. LOOK FOR CIGS DOWN TO 2 KFT IN THIS AREA INCLUDING AREAS NORTH OF A LINE FROM MCY TO FWA...AS LAKE MOISTURE MIXES WITH DAYTIME HEATING. A WEAK SHORTWAVE WILL PUSH INTO THE REGION THIS EVENING HELPING TO INCREASE LAKE SNOW INTENSITY SOME...VISIBILITIES MAY DROP TO 3/4SM OVER SOUTHERN LOWER MI AND EXTREME NORTHERN INDIANA THROUGH MUCH OF THE EVENING. EXPECTING DIURNAL CU TO DISSIPATE WITH SUNSET OVER EASTERN PORTIONS OF THE FA. OTHERWISE...GUSTY NW WINDS ARE EXPECTED THROUGH THE PERIOD. EXPECTING WINDS OF 10 T0 20 KNOTS WITH GUSTS UP TO 25 THIS EVENING. LOOK FOR A DECREASE IN LAKE SNOW INTENSITY AND A SHIFT NORTH THROUGH SUNDAY AS HIGH PRESSURE BRINGS LOWERING INVERSION HEIGHTS AND MICH DRIER AIR INTO THE REGION. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY UNTIL 10 AM EST /9 AM CST/ SUNDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ080-081. WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>079. OH...WIND CHILL ADVISORY UNTIL 10 AM EST SUNDAY FOR OHZ001-002-004- 005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 10 PM EST SUNDAY FOR LMZ043-046. FREEZING SPRAY ADVISORY UNTIL 5 AM EST SUNDAY FOR LMZ043-046. && $$ SHORT TERM...CHAMBERLAIN LONG TERM...MURPHY AVIATION...CHAMBERLAIN in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 111 AM EST SAT JAN 19 2008 .AVIATION... THE SYNOPTIC SNOW IS EXPECTED TO END SOON AT FWA AND SOME LAKE EFFECT SNOW IS HEADING THAT WAY...AFFECTING THE AIRPORT OFF AND ON. OBS AT FWA WENT TO VFR BUT THE SNOW COULD BRING CONDITIONS DOWN TO MVFR WHILE THE SNOW IS FALLING. QUESTION YET REMAINS FOR FWA LATER TODAY ON HOW MUCH OF THE LOWER...MVFR...LAKE EFFECT CLOUDS WILL PASS THROUGH FWA. AT THIS POINT WILL STAY WITH THE FORECAST BUT THIS WILL HAVE TO BE WATCHED. LAKE EFFECT SNOW IS MOVING THROUGH SBN BUT THE SNOW IS NOT DROPPING THE VISIBILITY. SO WILL CONTINUE WITH THE MVFR CEILINGS AND WILL HAVE TO WATCH TO SEE IF ANY HEAVIER BANDS WILL SET UP AND MOVE TOWARDS SBN. AT TAF ISSUANCE TIME THE WIND AT FWA WAS STILL SOUTHWESTERLY BUT WILL BE MOVING TO THE NORTHWEST AS THAT FRONT SOON MOVES THROUGH. THE WIND IS GOING TO STAY STRONG AND GUSTY OUT OF THE NORTHWEST THROUGH TODAY. && .UPDATE... /ISSUED 929 PM EST FRI JAN 18 2008/ QUICK UPDATE TO ADJUST THE POPS FOR THE FASTER TIMING OF THE PRECIP WITH THE ARCTIC FRONT MOVING ACROSS THE REGION. A QUICK .5 TO 1 INCH OF SNOW WILL BE POSSIBLE AS THE LINE MOVES ACROSS THE EASTERN HALF OF THE FORECAST AREA. MADE SOME MINOR ADJUSTMENTS TO TEMPS IN THE NEXT 12 HOURS WITH AN ADJUSTMENT TOWARDS THE LATEST RUC DATA. && .PREV DISCUSSION... /ISSUED 359 PM EST FRI JAN 18 2008/ SHORT TERM...TONIGHT THROUGH SUNDAY. NUMEROUS HAZARDS IN NEAR TERM. 13C/12HR TEMP FALL AT 8H/KABR WITH PASSAGE ARCTIC FROPA...SFC FRONT NOW POISED JUST NW OF CWA AT 20 UTC INTO NRN IL WITH STRONG ISALLOBARIC COUPLET/FNTL WAVE NEAR KSTL AIDING EXPANSION OF LRG AREA LIGHT SN. FURTHER MOISTURE FLUX/LAKE ENHANCEMENT TO PROVIDE HEAVIEST SNOW IMMEDIATELY DOWNWIND OF LK MI WHERE FNTL LIFT/DGZ/SATURATION ARE COLLOCATED. FURTHER DOWNSTREAM SATURATION LAGS HOURS BEHIND INTO COLDER AIRMASS...WHEN LES PROCESSES WILL TEND TO BECOME OVERALL DOMINANT. MINOR CHANGES WRT LES EVENT...ADDED ST. JOSEPH MI TO WINTER WEATHER ADVISORY AND EXTENDED ADVISORY INTO SUNDAY MORNING WITH MOISTURE DEPTH WRT ICE REMAINING AOA 4KFT UNTIL 15 UTC SUNDAY BEFORE STEERING FLOW BACKS AHEAD OF NEXT. DRAWN OUT SNOW ACCUMS/EACH PERIOD SUB ADVISORY CRITERIA/FOR SWRN 3 MI COUNTIES PRIMARY WINTER WX HAZARD WITH SECONDARY MINOR BLSN/WIND CHILL ADDING TO OVERALL PROLONGED WINTER WX HAZARD. PSBLY BEST POTENTIAL MAY BE SATURDAY NIGHT WITH RAISED DEPTH OF MOISTURE/SLIGHT SHORTWAVE PASSAGE RAISING MIXED HEIGHT WITH LAKE INDUCED CAPE OF 500-600 J/KG AND LK INDUCED EQL TO 9000 FEET. ELSEWHERE...WIND CHILL ADVISORY CRITERIA TO BE MET SATURDAY NIGHT TIMEFRAME...FIRST IN SWRN ZONES WHERE LACK OF LES CLOUDS/LIGHT FRESH SNOW ACCUMS FURTHER AIDING RADIATIONAL COOLING TO TAKE SFC TEMPS WELL BLO FREEZING...CONTD PREV FCST OF ABOUT M5F...WITH LOWEST APPARENT T OF M20-M23F SATURDAY NIGHT. COORDINATED MARINE NEARSHORE FREEZING SPRAY ADVISORY WITH KGRR WITH 11 AM ISSUANCE...20 TO 25 KNOTS AND GIVEN AIR TEMPS OVER WATER ANTICIPATE MODERATE ICE ACCRUAL TONIGHT INTO AT LEAST SATURDAY. OUTSIDE OF LAKE EFFECT AREA...HIGH PROBABILITY ACCUM TONIGHT...THOUGH GENERALLY AN INCH OR LESS...THEN OPTED FOR SCATTERED WORDING VS CHC IN LOW POP LES AREAS FOR SAT/SAT NIGHT. MORE FLURRIES SOUTH OF ROUTE 6 IN NRN IN/NRN OH SAT NIGHT AS IN CLOUD FLOW BACKS SLIGHTLY TO ABOUT 275-280...FAVORING MI AND PERHAPS BORDER CITIES IN ST. JOE/ELKHART COUNTIES. LONG TERM...SUNDAY NIGHT THROUGH FRIDAY. THE MAIN CHALLENGES OF THIS PERIOD CENTER ON THE DEVELOPMENT AND PROGRESSION OF THE LONG WAVE TROF ALONG THE WEST CONUS. THE 12Z ECMWF AND GFS OPERATIONAL RUNS BOTH SHEAR OUT AN UPPER TROF...HELPING A CUT OFF LOW TO FORM OVER CALIFORNIA BY TUESDAY. THIS LOW WILL ATTEMPT TO BECOME PHASED WITH THE MAIN UPPER FLOW AS SEVERAL SUBSEQUENT STRONG UPPER TROFS ALSO ATTEMPT TO DROP SOUTH INTO THE CONUS. THIS SCENARIO WILL EVENTUALLY PROVIDE A WIDE ARRAY OF UPPER AIR SOLUTIONS AS THESE SMALLER TROFS MOVE ACROSS WESTERN CANADA TOWARD THE CONUS. FSU/UCAR EXPERIMENTAL GRAPHICS INDICATE AVERAGE CONFIDENCE WITH THE PAST 5 GFS RUNS...BUT MOST OF THESE PAST RUNS HAVE SHOWN SIGNIFICANT UNCERTAINTY PAST TUESDAY. SO ALL THESE THINGS CONSIDERED...KEPT A CHANCE FOR SNOW MONDAY INTO TUESDAY WITH THE ARRIVAL OF THE FIRST SHORT WAVE. AFTER TUESDAY...KEPT TEMPERATURES WELL BELOW NORMAL...AND CLOSER TO THE 00Z MEX. LAKE EFFECT SNOW SHOWER CHANCES WILL NEED SOME FINE TUNING DOWN THE ROAD...BUT FOR NOW HAVE A CHANCE FOR SNOW OR LAKE EFFECT SNOW UNTIL FRIDAY. KEPT TEMPERATURES WELL BELOW NORMAL. STILL MUCH QUESTION IF ANOTHER STRONG ARCTIC FRONT WILL BE ABLE TO REACH THE AREA THURSDAY OR FRIDAY. FOR NOW...KEPT TEMPERATURES COLD HERE IN LIGHT OF EARLIER GFS RUNS. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WIND CHILL ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO 10 AM EST /9 AM CST/ SUNDAY FOR INZ003>009-012>018-020-022>027- 032>034. MI...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST SUNDAY FOR MIZ080-081. WINTER WEATHER ADVISORY UNTIL 10 AM EST SUNDAY FOR MIZ077>079. OH...WIND CHILL ADVISORY FROM 7 PM THIS EVENING TO 10 AM EST SUNDAY FOR OHZ001-002-004-005-015-016-024-025. LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST SUNDAY FOR LMZ043-046. FREEZING SPRAY ADVISORY UNTIL 7 PM EST THIS EVENING FOR LMZ043- 046. && $$ SHORT TERM...MURPHY LONG TERM...SKIPPER AVIATION...LOTHAMER UPDATE...SCHOTT in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 252 PM CST SUN JAN 20 2008 .DISCUSSION... DAYS 1-2... MAIN FORECAST HEADACHE WILL BE THE ARCTIC FRONT COMING DOWN TONIGHT AND TOMORROW, AND IF WE GET ANY PRECIP WITH IT. WV LOOP SHOWS TROUGH DIGGING INTO THE WESTERN CONUS, WITH THE 12Z UPPER AIR MAPS INDICATING 170 M HEIGHT FALLS ASSOCIATED WITH IT. 850MB TEMPS AT 12Z WERE A BIT WARMER THAN YESTERDAY, WITH A POCKET OF ABOVE ZERO C EVIDENT OVER THE WESTERN PLAINS. THE COLD AIR WAS NOT FAR BEHIND HOWEVER, WITH THE TEENS BELOW ZERO TO -20 C OVER MT BEHIND THE ARCTIC FRONT. AT THE SFC, WARM AIR HAS PUSHED NORTHWARD ACROSS MUCH OF THE CWA, WITH TEMPERATURES GETTING INTO THE 40S, WHILE THE TEENS REMAIN OVER NEB. MODELS ARE ALL IN PRETTY GOOD AGREEMENT ON THE TEMPERATURE GRADIENT TIGHTENING OVERNIGHT AS THE UPPER TROUGH CONTINUES TO DIG AND THE SFC LOW GETS CENTERED NEAR EHA. THE GFS, NAM, AND UKMET ARE ALL IN PRETTY GOOD AGREEMENT ON BRINGING THE COLD FRONT DOWN A BIT SLOWER THAN YESTERDAY`S RUNS, PUTTING THE BOUNDARY NEAR THE CENTRAL CWA AT 12Z. THE RUC AND SREF MEAN ARE EVEN SLOWER THAN THIS SOLUTION. ARCTIC AIR OFTEN COMES DOWN FASTER THAN EXPECTED, BUT THE BOUNDARY HAS STAYED FAIRLY STATIONARY OVER FAR NORTHERN KS THROUGHOUT THE DAY TODAY. WILL LEAN MORE TOWARDS THE NAM/GFS FOR NOW. THUS, BUMPED UP OVERNIGHT LOWS A BIT OVER OUR SOUTHERN AND CENTRAL COUNTIES INTO THE 20S. ALSO BUMPED UP HIGHS IN OUR SOUTHEAST FOR TOMORROW, ALTHOUGH FULLY EXPECT THERE WILL BE A NON-DIURNAL TEMPERATURE PATTERN FOR MOST OF THE CWA, WITH FALLING TEMPS AFTER THE FRONT COMES THROUGH. THE COLD FRONT SHOULD MOVE THE REST OF THE WAY THROUGH THE CWA BY LATE MONDAY AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW A FAIRLY SHALLOW MOIST LAYER BELOW 700MB. GFS AND NAM SHOW SOME DECENT ISENTROPIC LIFT AT 285 K OVER OUR SOUTHEASTERN CORNER BY MONDAY EVENING. THINK THIS AREA AS WELL AS THE FAR NORTH WILL SEE THE BEST, IF FAIRLY MINOR, SHOT AT GETTING ANYTHING MEASURABLE. THUS, ADJUSTED GRIDS TO REFLECT THE SLIGHTLY HIGHER POPS IN THAT AREA. STILL, WITH THE SHALLOW MOISTURE DON`T EXPECT TO SEE MUCH. WITH THE DRY MID-LEVELS, THINK THAT FZDL LOOKS MOST LIKELY TYPE, ALTHOUGH WE COULD GET SOME SNOWFLAKES MIXING IN AS THE TEMPS GET CLOSER TO -10 C. ANY PRECIP SHOULD TAPER OFF MONDAY EVENING AS THE FLOW SPLITS AND THE NORTHERN BRANCH SHORTWAVE DIGS INTO THE CENTRAL PLAINS, DRIVING THE HIGH PRESSURE CENTER SOUTH. CONDITIONS SHOULD BE QUIET PRECIP-WISE BY TUESDAY, ALTHOUGH COLD. THINK THAT CLOUDS SHOULD BEGIN TO BREAK UP AFTER MIDNIGHT MONDAY NIGHT, AND WITH ARCTIC AIR IN PLACE TEMPS SHOULD DROP LIKE A ROCK. HYS, WHICH STILL HAS SNOWCOVER, COULD EVEN SEE LOWS DIP BELOW ZERO F. CONTINUED WITH LOWS IN THE SINGLE DIGITS ELSEWHERE IN THE AREA. THE SFC HIGH WILL REMAIN IN PLACE TUESDAY AS THE UPPER FLOW BECOMES MORE NORTHWESTERLY. WITH 850MB TEMPS BELOW -10 C, HIGHS WILL NOT GET VERY FAR EVEN WITH SUNSHINE, STAYING MOSTLY IN THE 20S. DAYS 3-7... NO MAJOR CHANGES PLANNED TO THE LATER PERIODS. WILL HOWEVER BE INTERESTING IN HOW MUCH OF A WARM UP THAT WILL OCCUR LATE WEEK AS A S/W RIDGE BUILDS INTO THE AREA. MODELS AND ENSEMBLES TODAY CONTINUE TO HINT AT A RETROGRADING/REDEVELOPING RIDGE FROM ROUGHLY 140W TO 160W LATE WEEK. THIS WILL ALLOW FOR AN UPPER LOW TO REMAIN FIRMLY ANCHORED OVER THE SW CONUS. S/W RIDGE BUILDING INTO THE AREA TOWARDS THE WEEKEND SHOULD ENHANCE LEE SIDE TROFING FROM THE WESTERLY DOWNSLOPE FLOW ALONG WITH INCREASING WINDS AND WARMER TEMPS. HAVE THEREFORE BUMPED TEMPS UP A FEW MORE DEGREES BY THE WEEKEND PERIOD. MAY EVEN NEED TO BE BUMPED UP SOME MORE IF THIS TREND VERIFIES. -BURGERT .AVIATION... THROUGH THE FIRST HALF OF THE NIGHT WILL HAVE ONLY CI TO CONTEND WITH ACROSS SOUTHWEST KANSAS. AFTER 9Z HOWEVER THINGS WILL CHANGE. A STRONG COLD FRONT WILL CROSS AREA AND AS IT DOES WINDS WILL QUICKLY SHIFT TO THE NORTHWEST AND INCREASE INTO THE 15 TO 25 MPH RANGE. BOTH NAM/GFS TODAY WERE SLOWER AND SIMILAR IN TIMING OF OUR WIND SHIFT SO OPTED TO USE THESE MODELS AS A GUIDE FOR TIMING OF FROPA. BEHIND THIS FRONT SFC-925RH FIELD QUICKLY SATURATE SO HAVE THEREFORE QUICKLY INTRODUCED LOW CLOUDS BEHIND THIS FRONT. PCPN STILL LOOKS LIKE A POSSIBILITY AS LOW CLOUDS RETURN EARLY MONDAY MORNING. ALTHOUGH THIS IS TOWARDS THE END OF THE TAF PERIOD HAVE DECIDED TO INCLUDE LIGHT FZDZ OR SN INTO THE TAFS. && .PRELIMINARY POINT TEMPS/POPS... DDC 20 26 3 21 / 0 10 10 0 GCK 17 20 0 23 / 10 20 10 0 EHA 18 25 8 26 / 0 10 10 0 LBL 22 28 5 26 / 0 10 10 0 HYS 11 18 -1 19 / 10 20 10 0 P28 25 38 8 25 / 0 20 20 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN26/18 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1040 AM MST SAT JAN 19 2008 .AVIATION... FOR THE 18Z TAF...VFR CONDITIONS WILL PERSIST THROUGH THE TAF PERIOD. THE SKIES WILL REMAIN SCT-BKN WITH MID-HIGH LEVEL CLOUDS AND SOUTHWESTERLY WINDS LESS THAN 15 KNOTS. && .PREV DISCUSSION... /ISSUED 232 AM MST SAT JAN 19 2008/ .DISCUSSION... 05Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED SHORT WAVE TROUGH SLIDING ACROSS SOUTHERN COLORADO AROUND BASE OF LONG WAVE TROUGH ACROSS EASTERN CONUS. LEADING EDGE OF 110KT H3 JET STREAK WAS BEGINNING TO MOVE ACROSS AREA BEHIND TROUGH. AT THE SFC...1033MB HIGH WAS DRAPED ACROSS NEBRASKA AND KANSAS...AND SFC TROUGH WAS LOCATED ACROSS SE CO. OVERALL...BOTH THE NAM AND GFS INITIALIZED RELATIVELY WELL AT 00Z. ALTHOUGH AT H3 BOTH MODELS SEEMED TO BE TO FAR NORTH WITH JET MAX BEHIND SE CO TROUGH. TODAY-TONIGHT...PRECIPITATION CHANCES...IF ANY THROUGH THE MORNING HOURS WILL BE THE FIRST PROBLEM TO DEAL WITH TODAY. PREVIOUSLY MENTIONED SHORT WAVE TROUGH WILL BE TO THE SOUTH OF THE WEST OF THE AREA BY 12Z TODAY AND ANY LINGERING PRECIPITATION WITH THAT WILL BE WELL AWAY FROM THE AREA...HOWEVER 110KT JET STREAK LEFT ENTRANCE REGION WILL BE OVER THE AREA. AS TROUGH SHIFTS EAST...DEEP WARM AIR ADVECTION WILL ALSO BE TAKING PLACE AS RIDGE BUILDS IN. AS TEMPERATURES WARM...AREA OF STEEPER LAPSE RATES OBSERVED ON KDNR RAOB WILL SHIFT WILL ALSO SHIFT TO THE EAST AND NOT REALLY BE LINED UP THAT GREAT WITH AVAILABLE ISENTROPIC ASCENT. DEEP LAYER DIV Q VECTORS SUGGEST THAT SUBSIDENCE FROM BUILDING RIDGE WILL GENERALLY BEAT OUT TEMPERATURE ADVECTION EFFECTS...ALTHOUGH H7-H5 LAYER DOES SUPPORT SOME FORCING FOR ASCENT ACROSS CENTRAL PARTS OF THE AREA BY AROUND 12Z. CROSS SECTIONS ALSO SHOW FAIRLY DEEP FRONTOGENESIS ALL ALONG TEMP GRADIENT ACROSS THE AREA WITH POCKET OF POTENTIAL INSTABILITY JUST ABOVE FRONTAL SURFACE. MAIN QUESTION IS WHETHER OR NOT THIS LAYER WILL BE SATURATED OR NOT. NAM AND GFS...DESPITE LARGE DIFFERENCES IN QPF (DRY VS LIGHT) ACTUALLY SEEM TO HAVE VERY SIMILAR FORCING STABILITY FIELDS WITH BIG DIFFERENCE IN HOW DRY AIRMASS BELOW FRONTAL SURFACE IS. WITH OBSERVED SOUNDINGS UPSTREAM TENDING TO SUPPORT DRIER NAM. FOR NOW THINK WILL GO WITH FLURRIES IN THE MORNING AND ADJUST BASED ON EARLY MORNING TRENDS. RIDGE WILL BEGIN TO FLATTEN OVERNIGHT WITH PERSISTENT...WEAK...WARM AIR ADVECTION ACROSS MUCH OF THE AREA ESPECIALLY BETWEEN H7 AND H5. CROSS SECTIONS ACROSS THE AREA ALONG WITH POINT SOUNDINGS INDICATE AREA WITH WEAK LIFT ALSO VERY STABLE. ALTHOUGH THERE APPEARS TO BE WEAK LIFT IN A SATURATED DENDRITIC LAYER ACROSS THE NORTH...THINK WEAK FORCING AND STABLE AIRMASS WOULD NOT BE ABLE TO PRODUCE ANYTHING STRONG ENOUGH TO MAKE IT THROUGH VERY DRY LAYER JUST OFF THE SURFACE. SUNDAY-SUNDAY NIGHT...NEXT SHORT WAVE TROUGH WILL BEGIN TO MOVE INTO THE WESTERN CONUS THROUGH THE DAY. SFC LOW WILL DEVELOP ACROSS EASTERN COLORADO IN RESPONSE AND SLOWLY MOVE SOUTH...BRINGING A COLD FRONT ACROSS THE AREA IN THE PROCESS. SHORT RANGE MODELS ALL BEGIN TO BREAK OUT LIGHT PRECIP ACROSS THE AREA BEHIND THE FRONT...MAINLY IN THE EVENING. SOUNDINGS WOULD SUGGEST THAT PRECIPITATION PROCESSES WILL BE VERY SHALLOW AS ATMOSPHERE WILL BE SATURATED FROM ONLY H8 AND DOWN. WITH EASTERLY WINDS ENHANCING ANY LARGE SCALE FORCING ABOVE THE FRONTAL SURFACE THINK THERE WILL BE A CHANCE FOR SOME VERY LIGHT PRECIP IF BOUNDARY LAYER CAN SATURATE. ALTHOUGH MODELS SUGGEST THIS WILL HAPPEN...LOOKING AT HOW DRY THE AIR IS TO THE EAST OF THE CWA CURRENTLY AM WORRIED THAT MODELS MAY BE OVERDOING AVAILABLE MOISTURE...ESPECIALLY WHEN FLOW BEGINS TO BECOME NORTHEAST BEHIND THE FRONT. SOUNDINGS ACTUALLY LOOK ALOT LIKE A DRIZZLE/FREEZING DRIZZLE SOUNDING WITH SHALLOW SATURATED LAYER CAPPED BY FAIRLY STRONG SHEAR. ATMOSPHERE WILL GRADUALLY COOL BEHIND THE FRONT...BUT THERE COULD BE A WINDOW OF LIGHT FZDZ BEFORE THINGS CHANGE OVER TO LIGHT SNOW. OVERNIGHT...DIV Q FIELDS INDICATE LARGE SCALE FORCING FOR ASCENT BEGIN TO INCREASE ACROSS THE NORTHWEST CWA AS TROUGH APPROACHES. THIS IS ALSO ACCOMPANIED BY INCREASING FRONTOGENESIS BETWEEN H7 AND H6. STILL CONCERNED ABOUT PERSISTENT DRY LVL MAY HINDER PRECIPITATION FORMATION AND KEEP THINGS SHALLOW...BUT WILL PUT HIGHEST POPS IN THE NORTHWEST TO ACCOUNT FOR BETTER FORCING. WINDS SHOULD STAY IN THE 10 TO 20 MPH RANGE OVERNIGHT AS FRONT MOVES THROUGH THE AREA...AND WITH THE EXPECTED VERY COLD AIR EXPECTED BEHIND THE FRONT THINK WE WILL SEE WIND CHILLS IN TO -10 TO -20 RANGE. A LITTLE EARLY TO ISSUE ANY KIND OF HEADLINE BUT WILL MENTION IN HWO. MONDAY-MONDAY NIGHT...H5 TROUGH AXIS WILL BEGIN TO NEAR THE AREA DURING THE MORNING. CROSS SECTIONS THROUGH THE H85-H3 THICKNESS GRADIENT INDICATE A DECENT AMOUNT OF FRONTOGENESIS AS TROUGH APPROACHES...PARTICULARLY AROUND 675MB. SAME PROBLEM AS SUNDAY IS APPARENT ON THIS CROSS SECTION THOUGH...ENTIRE AIRMASS ABOVE FRONTAL SURFACE IS NOT SATURATED...AND BY MONDAY AFTERNOON IS FAIRLY DRY. POINT SOUNDINGS HOWEVER INDICATE THE SURFACE TO THE FRONTAL INVERSION SHOULD FALL INTO THE DENDRITIC GROWTH ZONE...SO WE MAY SEE FAIRLY WIDESPREAD VERY LIGHT SNOW/FLURRIES DURING THE DAY...EVEN THOUGH BEST FORCING IS IN DRY LAYER. OVERALL WOULD NOT ANTICIPATE MUCH IN THE WAY OF ACCUMULATION AT THIS TIME...BUT DID BUMP UP POPS SOMEWHAT ON MONDAY. VERY COLD AIR LOOKING TO BE OVER THE REGION AT THIS TIME WITH MODELS AVERAGING H85 TEMPS AROUND -15C DURING THE AFTERNOON. BASED ON OBSERVED TEMPS UPSTREAM TODAY...WOULDNT BE SURPRISED IF AIRMASS WAS EVEN COLDER THAN CURRENT MODELS. LOWERED MAX TEMPS INTO SINGLE DIGITS/LOW TEENS...A BIT COLDER THAN OPERATIONAL MODELS SUGGEST. OVERNIGHT LOWS WILL BE A TOUGH CALL AS SFC HIGH PRESSURE WILL SETTLE OVER THE AREA RELAXING WINDS...AND WITH VERY COLD TEMPS ALREADY IN PLACE...TEMPERATURES COULD REALLY PLUMMET. CLOUDS MAY HOLD TEMPS UP...BUT WITH SUBSIDENCE OVERSPREADING THE AREA THINK GOING COLD WILL BE THE WAY TO GO AND WENT WITH LOWS SEVERAL DEGREES BELOW ZERO. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ KJ/JRM ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 232 AM MST SAT JAN 19 2008 .DISCUSSION... 05Z WATER VAPOR IMAGERY/RUC ANALYSIS INDICATED SHORT WAVE TROUGH SLIDING ACROSS SOUTHERN COLORADO AROUND BASE OF LONG WAVE TROUGH ACROSS EASTERN CONUS. LEADING EDGE OF 110KT H3 JET STREAK WAS BEGINNING TO MOVE ACROSS AREA BEHIND TROUGH. AT THE SFC...1033MB HIGH WAS DRAPED ACROSS NEBRASKA AND KANSAS...AND SFC TROUGH WAS LOCATED ACROSS SE CO. OVERALL...BOTH THE NAM AND GFS INITIALIZED RELATIVELY WELL AT 00Z. ALTHOUGH AT H3 BOTH MODELS SEEMED TO BE TO FAR NORTH WITH JET MAX BEHIND SE CO TROUGH. TODAY-TONIGHT...PRECIPITATION CHANCES...IF ANY THROUGH THE MORNING HOURS WILL BE THE FIRST PROBLEM TO DEAL WITH TODAY. PREVIOUSLY MENTIONED SHORT WAVE TROUGH WILL BE TO THE SOUTH OF THE WEST OF THE AREA BY 12Z TODAY AND ANY LINGERING PRECIPITATION WITH THAT WILL BE WELL AWAY FROM THE AREA...HOWEVER 110KT JET STREAK LEFT ENTRANCE REGION WILL BE OVER THE AREA. AS TROUGH SHIFTS EAST...DEEP WARM AIR ADVECTION WILL ALSO BE TAKING PLACE AS RIDGE BUILDS IN. AS TEMPERATURES WARM...AREA OF STEEPER LAPSE RATES OBSERVED ON KDNR RAOB WILL SHIFT WILL ALSO SHIFT TO THE EAST AND NOT REALLY BE LINED UP THAT GREAT WITH AVAILABLE ISENTROPIC ASCENT. DEEP LAYER DIV Q VECTORS SUGGEST THAT SUBSIDENCE FROM BUILDING RIDGE WILL GENERALLY BEAT OUT TEMPERATURE ADVECTION EFFECTS...ALTHOUGH H7-H5 LAYER DOES SUPPORT SOME FORCING FOR ASCENT ACROSS CENTRAL PARTS OF THE AREA BY AROUND 12Z. CROSS SECTIONS ALSO SHOW FAIRLY DEEP FRONTOGENESIS ALL ALONG TEMP GRADIENT ACROSS THE AREA WITH POCKET OF POTENTIAL INSTABILITY JUST ABOVE FRONTAL SURFACE. MAIN QUESTION IS WHETHER OR NOT THIS LAYER WILL BE SATURATED OR NOT. NAM AND GFS...DESPITE LARGE DIFFERENCES IN QPF (DRY VS LIGHT) ACTUALLY SEEM TO HAVE VERY SIMILAR FORCING STABILITY FIELDS WITH BIG DIFFERENCE IN HOW DRY AIRMASS BELOW FRONTAL SURFACE IS. WITH OBSERVED SOUNDINGS UPSTREAM TENDING TO SUPPORT DRIER NAM. FOR NOW THINK WILL GO WITH FLURRIES IN THE MORNING AND ADJUST BASED ON EARLY MORNING TRENDS. RIDGE WILL BEGIN TO FLATTEN OVERNIGHT WITH PERSISTENT...WEAK...WARM AIR ADVECTION ACROSS MUCH OF THE AREA ESPECIALLY BETWEEN H7 AND H5. CROSS SECTIONS ACROSS THE AREA ALONG WITH POINT SOUNDINGS INDICATE AREA WITH WEAK LIFT ALSO VERY STABLE. ALTHOUGH THERE APPEARS TO BE WEAK LIFT IN A SATURATED DENDRITIC LAYER ACROSS THE NORTH...THINK WEAK FORCING AND STABLE AIRMASS WOULD NOT BE ABLE TO PRODUCE ANYTHING STRONG ENOUGH TO MAKE IT THROUGH VERY DRY LAYER JUST OFF THE SURFACE. SUNDAY-SUNDAY NIGHT...NEXT SHORT WAVE TROUGH WILL BEGIN TO MOVE INTO THE WESTERN CONUS THROUGH THE DAY. SFC LOW WILL DEVELOP ACROSS EASTERN COLORADO IN RESPONSE AND SLOWLY MOVE SOUTH...BRINGING A COLD FRONT ACROSS THE AREA IN THE PROCESS. SHORT RANGE MODELS ALL BEGIN TO BREAK OUT LIGHT PRECIP ACROSS THE AREA BEHIND THE FRONT...MAINLY IN THE EVENING. SOUNDINGS WOULD SUGGEST THAT PRECIPITATION PROCESSES WILL BE VERY SHALLOW AS ATMOSPHERE WILL BE SATURATED FROM ONLY H8 AND DOWN. WITH EASTERLY WINDS ENHANCING ANY LARGE SCALE FORCING ABOVE THE FRONTAL SURFACE THINK THERE WILL BE A CHANCE FOR SOME VERY LIGHT PRECIP IF BOUNDARY LAYER CAN SATURATE. ALTHOUGH MODELS SUGGEST THIS WILL HAPPEN...LOOKING AT HOW DRY THE AIR IS TO THE EAST OF THE CWA CURRENTLY AM WORRIED THAT MODELS MAY BE OVERDOING AVAILABLE MOISTURE...ESPECIALLY WHEN FLOW BEGINS TO BECOME NORTHEAST BEHIND THE FRONT. SOUNDINGS ACTUALLY LOOK ALOT LIKE A DRIZZLE/FREEZING DRIZZLE SOUNDING WITH SHALLOW SATURATED LAYER CAPPED BY FAIRLY STRONG SHEAR. ATMOSPHERE WILL GRADUALLY COOL BEHIND THE FRONT...BUT THERE COULD BE A WINDOW OF LIGHT FZDZ BEFORE THINGS CHANGE OVER TO LIGHT SNOW. OVERNIGHT...DIV Q FIELDS INDICATE LARGE SCALE FORCING FOR ASCENT BEGIN TO INCREASE ACROSS THE NORTHWEST CWA AS TROUGH APPROACHES. THIS IS ALSO ACCOMPANIED BY INCREASING FRONTOGENESIS BETWEEN H7 AND H6. STILL CONCERNED ABOUT PERSISTENT DRY LVL MAY HINDER PRECIPITATION FORMATION AND KEEP THINGS SHALLOW...BUT WILL PUT HIGHEST POPS IN THE NORTHWEST TO ACCOUNT FOR BETTER FORCING. WINDS SHOULD STAY IN THE 10 TO 20 MPH RANGE OVERNIGHT AS FRONT MOVES THROUGH THE AREA...AND WITH THE EXPECTED VERY COLD AIR EXPECTED BEHIND THE FRONT THINK WE WILL SEE WIND CHILLS IN TO -10 TO -20 RANGE. A LITTLE EARLY TO ISSUE ANY KIND OF HEADLINE BUT WILL MENTION IN HWO. MONDAY-MONDAY NIGHT...H5 TROUGH AXIS WILL BEGIN TO NEAR THE AREA DURING THE MORNING. CROSS SECTIONS THROUGH THE H85-H3 THICKNESS GRADIENT INDICATE A DECENT AMOUNT OF FRONTOGENESIS AS TROUGH APPROACHES...PARTICULARLY AROUND 675MB. SAME PROBLEM AS SUNDAY IS APPARENT ON THIS CROSS SECTION THOUGH...ENTIRE AIRMASS ABOVE FRONTAL SURFACE IS NOT SATURATED...AND BY MONDAY AFTERNOON IS FAIRLY DRY. POINT SOUNDINGS HOWEVER INDICATE THE SURFACE TO THE FRONTAL INVERSION SHOULD FALL INTO THE DENDRITIC GROWTH ZONE...SO WE MAY SEE FAIRLY WIDESPREAD VERY LIGHT SNOW/FLURRIES DURING THE DAY...EVEN THOUGH BEST FORCING IS IN DRY LAYER. OVERALL WOULD NOT ANTICIPATE MUCH IN THE WAY OF ACCUMULATION AT THIS TIME...BUT DID BUMP UP POPS SOMEWHAT ON MONDAY. VERY COLD AIR LOOKING TO BE OVER THE REGION AT THIS TIME WITH MODELS AVERAGING H85 TEMPS AROUND -15C DURING THE AFTERNOON. BASED ON OBSERVED TEMPS UPSTREAM TODAY...WOULDNT BE SURPRISED IF AIRMASS WAS EVEN COLDER THAN CURRENT MODELS. LOWERED MAX TEMPS INTO SINGLE DIGITS/LOW TEENS...A BIT COLDER THAN OPERATIONAL MODELS SUGGEST. OVERNIGHT LOWS WILL BE A TOUGH CALL AS SFC HIGH PRESSURE WILL SETTLE OVER THE AREA RELAXING WINDS...AND WITH VERY COLD TEMPS ALREADY IN PLACE...TEMPERATURES COULD REALLY PLUMMET. CLOUDS MAY HOLD TEMPS UP...BUT WITH SUBSIDENCE OVERSPREADING THE AREA THINK GOING COLD WILL BE THE WAY TO GO AND WENT WITH LOWS SEVERAL DEGREES BELOW ZERO. && .AVIATION...FOR THE 06Z TAF...THE LIGHT SNOW HAS MOVED TO THE SOUTH OF BOTH TAF SITES. PERSISTENT MIDDLE AND UPPER LEVEL LIFT WILL KEEP CLOUD COVER ACROSS THE AREA. HOWEVER...EVEN WITH ALL THE CLOUDS...THE CEILINGS SHOULD REMAIN VFR EXCEPT FOR THE KMCK TAF THIS AFTERNOON. AT THAT TIME...CEILINGS SHOULD DROP INTO THE HIGH END OF THE MVFR RANGE. WINDS WILL REMAIN LIGHT AND GRADUALLY SWING AROUND TO THE SOUTH AND SOUTHWEST AS THE DAY PROGRESSES. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ JRM/BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1029 PM MST FRI JAN 18 2008 .AVIATION...FOR THE 06Z TAF...THE LIGHT SNOW HAS MOVED TO THE SOUTH OF BOTH TAF SITES. PERSISTANT MIDDLE AND UPPER LEVEL LIFT WILL KEEP CLOUD COVER ACROSS THE AREA. HOWEVER...EVEN WITH ALL THE CLOUDS...THE CEILINGS SHOULD REMAIN VFR EXCEPT FOR THE KMCK TAF THIS AFTERNOON. AT THAT TIME...CEILINGS SHOULD DROP INTO THE HIGH END OF THE MVFR RANGE. WINDS WILL REMAIN LIGHT AND GRADUALLY SWING AROUND TO THE SOUTH AND SOUTHWEST AS THE DAY PROGRESSES. && .PREV DISCUSSION... /ISSUED 836 PM MST FRI JAN 18 2008/ .UPDATE...JUST COMPLETED ANOTHER UPDATE. WHAT LOOKED PROMISING EARLIER FOR SOME MEASURABLE SNOW DID NOT MATERIALIZE...MAINLY TO THE EAST OF THE COLORADO BORDER. HAS BEEN SNOWING NEARLY 2 HOURS AT KITR JUST 30 MILES AWAY. HOWEVER...NOT EVEN A FLAKE AT KGLD. VERY TIGHT GRADIENT. MOST OF THE LIFT AND MOISTURE WILL REMAIN OVER THE SOUTHWEST QUARTER OF THE FORECAST AREA THROUGH THE REST OF TONIGHT. SO WILL KEEP LIKELY THERE. ALSO LOWERED MINS...MAINLY IN THE EAST WHERE THE LEAST AMOUNT OF CLOUD COVER RESIDES. ALSO UPDATED WINDS ON LASTEST OBSERVATIONS AND RUC. WOULD HAVE LIKED TO HAVE TAKEN SNOW OUT OF TOMORROW MORNING SINCE BELIEVE IT WILL BE ALL DONE BY THEN. HOWEVER...WILL LET IT RIDE SO CAN STAY WITHIN COLLABORATION THRESHOLDS. && .PREV DISCUSSION... /ISSUED 547 PM MST FRI JAN 18 2008/ .UPDATE...JUST COMPLETED AN UPDATE. COVERAGE AND INTENSITY OF SNOW ALREADY PICKING BASED LATEST SATELLITE...RADAR...AND SURFACE OBSERVATIONS. GFS LOOKS TO BE CAPTURING THE SNOW AREA THE BEST. RADAR AND SATELLITE INDICATING SOME BANDED STRUCTURE. PROFILER NETWORK SHOWING AREA IN WEAK RIGHT REAR QUADRANT OF THE JET. VERY GOOD LAPSE RATES IN PLACES AS STRONG MID LEVEL LIFT/FRONTOGENESIS IS MOVING ACROSS. SO RAISED THE POPS...QPF...AND SNOWFALL AMOUNTS IN THE WESTERN HALF TO TWO THIRDS WHERE THE BEST MOISTURE AND LIFT LINE UP. HAVE AMOUNTS OF 1 TO 2 INCHES. HOWEVER...IF THE GFS QPF ENDS UP BEING RIGHT...I AM TOO LOW. ALSO LOOKS LIKE SOME LINGERING MID AND JET LEVEL LIFT LINGERS INTO THE 6Z TO 12Z TIME FRAME. HOWEVER...DEEPER MOISTURE DECREASES/MOVES TO THE SOUTH DURING THIS TIME. SO KEPT POPS AND WX IN FOR THE ENTIRE 12 HOUR PERIOD. WILL FINE TUNE LATER AS TRENDS INDICATE. ALSO TWEEKED HOURLY TRENDS ON OTHER ELEMENTS BASED ON CURRENT TRENDS. && .PREV DISCUSSION... /ISSUED 450 PM MST FRI JAN 18 2008/ .AVIATION...ISOLATED FLURRIES TO VERY LIGHT SNOW SHOWERS WILL SPREAD ACROSS THE TRI-STATE REGION AND INCREASE IN COVERAGE BETWEEN 00Z-06Z. VFR CONDITIONS WILL BECOME MVFR WITH LOWER CEILINGS AND VISIBILITIES WITH INTERMITTENT IFR CONDITIONS AND LIGHT SNOW SHOWERS ENDING BETWEEN 08Z-10Z. MVFR CONDITIONS WILL THEN IMPROVE TO VFR BETWEEN 11-13Z. && .PREV DISCUSSION... /ISSUED 212 PM MST FRI JAN 18 2008/ .DISCUSSION...FORECAST CONCERNS INCLUDE TIMING OF ISOLATED FLURRIES IN THE SHORT TERM...ENDING SATURDAY MORNING...AND MORE WIDESPREAD LIGHT SNOW FROM SUNDAY NIGHT THROUGH MONDAY NIGHT. ALSO...UNCERTAIN HOW COLD THE LOWS WILL BE BEHIND THE STRONG COLD FRONT ON MONDAY. BROAD LARGE SCALE TROUGH IS BEGINNING TO SLOWLY TRANSLATE EASTWARD THROUGH THE CENTRAL CONUS...BUT NOT BEFORE A FEW VERY SMALL DISTURBANCES ALONG THE FAR WESTERN EDGE OF THAT TROUGH INITIATE SOME ISOLATED TO SCATTERED LIGHT SNOW UPSTREAM OF THE GLD CWA. EXPECT THESE FLURRIES OR LIGHT SNOW SHOWERS TO ARRIVE HERE AFTER 00Z AND FINISH BY 09Z LEAVING LIGHT SNOWFALL AMOUNTS TOTALING A TRACE TO ONE INCH. A BRIEF PERIOD OF SOUTHERLY WINDS ON SATURDAY WILL CONTRIBUTE TO SLIGHTLY WARMER TEMPERATURES AHEAD OF A STRONG PUSH OF ARCTIC AIR FROM THE NORTH. SUNDAY THROUGH MONDAY...NEXT UPPER TROUGH DIGS DOWN THROUGH THE WESTERN CONUS BEGINNING LATE SUNDAY WHILE DRASTICALLY LOWERING TEMPERATURES ACROSS THE CENTRAL CONUS. HIGH TEMPERATURES ON MONDAY EXPECTED TO ONLY REACH INTO THE MID TEENS WITH LOW TEMPERATURES ON TUESDAY MORNING EASILY REACHING THE ZERO TO NEGATIVE 5 DEGREE RANGE. MODEL TRENDS INDICATE ARRIVAL OF PRECIPITATION WITH THIS SYSTEM WILL BE SLOWED WHEN COMPARED TO PREVIOUS MODEL RUNS. ADJUSTED POP AND WEATHER GRIDS TO REFLECT THIS. PRECIPITATION ENDS LATE MONDAY INTO EARLY TUESDAY. AS THIS LARGE SCALE TROUGH WASHES OUT OVER THE INTER-MOUNTAIN WEST...SOUTHWESTERLY TO NEAR ZONAL UPPER FLOW PERSISTS THROUGH THE REST OF THE WEEK WITH TEMPERATURES ONLY GRADUALLY MODERATING. && .EXTENDED...THURSDAY & FRIDAY... UPPER FLOW BECOMES SOMEWHAT ZONAL DURING THE BEGINNING OF THIS PERIOD...ALLOWING TEMPERATURES TO RISE A BIT FROM THE BITTER COLD TEMPERATURES SEEN EARLIER IN THE WEEK. EVEN WITH THAT BEING SAID...THE TEMPERATURES ARE NOT EXPECTED TO RISE ABOVE FREEZING ON THURSDAY BUT SHOULD WARM UP INTO THE MID 30S BY FRIDAY AS THE SURFACE HIGH PRESSURE CONTINUES TO PUSH EAST AND WE RETURN TO SOUTHERLY FLOW. THE EUROPEAN BRINGS AN H5 LOW OVER THE REGION FRIDAY WHILE THE GFS BRINGS IN A FEW SHORTWAVE TROUGHS...HAVE KEPT POPS RELATIVELY LOW AT THIS POINT AS UNCERTAINTY AT THIS RANGE OF TIME IS HIGH. && .AVIATION...CLOUD COVER WILL GRADUALLY INCREASE ACROSS KGLD & KMCK THROUGHOUT THE TAF PERIOD. VFR CONDITIONS WILL PREVAIL THROUGH 21Z...AFTERWARDS MVFR CONDITIONS WILL EXIST THROUGH 08Z WITH CEILINGS AROUND 2K AND SOME LIGHT SNOW. VFR CONDITIONS SHOULD RETURN TO THE TERMINALS AFTER 08Z. && && && && && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 354 AM CST SAT JAN 19 2008 .DISCUSSION... MAIN FORECAST CONCERN IN THE NEAR TERM IS BITTERLY COLD TEMPERATURE REGIME WITH SUB-ZERO WIND CHILLS IN NORTHERN AREAS THIS MORNING. OUR FOCUS THEN TURNS TO THE CHANCE OF PRECIPITATION WITH THE NEXT SYSTEM MONDAY NIGHT AND TUESDAY. COLD FRONT JUST DEPARTING THE PENNYRILE REGION OF WESTERN KENTUCKY THIS MORNING. SATELLITE INDICATES BROKEN SKY CONDITION OVER MUCH OF THE AREA...BUT CLEARING SHOULD PROGRESS FAIRLY QUICKLY FROM WEST TO EAST THIS MORNING SAVE FOR SOME LINGERING HIGH CLOUDS SOUTHEAST OF THE OHIO RIVER. SIGNIFICANT COLD AIR ADVECTION WILL CONTINUE THROUGH MID MORNING...WITH TEMPERATURES POSSIBLY BOTTOMING OUT NEAR 10 DEGREES BY 8 OR 9 AM NEAR MOUNT VERNON ILLINOIS. PAIRED WITH NORTHWEST WINDS OF 10 TO 15 MPH...THIS WILL CREATE SUB-ZERO WIND CHILLS OVER NORTHERN PORTIONS OF SOUTHEAST MISSOURI...SOUTHERN ILLINOIS...AND INTO SOUTHWEST INDIANA. WILL HEADLINE FORECAST ACCORDINGLY. LATER TODAY...TEMPERATURES WILL HAVE A HARD TIME RECOVERING DESPITE ABUNDANT SUNSHINE. MET GUIDANCE APPEARS TO HAVE THE BEST HANDLE ON THE INCOMING COLD AIR...AND THAT STILL DOESN/T SEEM COLD ENOUGH. DECIDED TO UTILIZE RUC SURFACE TEMPERATURE FORECAST INSTEAD FOR MUCH OF THE DAY. TONIGHT WILL BE THE COLDEST NIGHT OF THE NEXT SEVEN DAYS...WITH LOWS BOTTOMING OUT IN THE SINGLE DIGITS EXCEPT NEAR THE TENNESSEE AND ARKANSAS STATE LINES. AGAIN...MET GUIDANCE IS PREFERRED. TEMPERATURES WILL BEGIN TO MODERATE ON SUNDAY AS A WARM ADVECTION PATTERN BECOMES ESTABLISHED OVER THE PLAINS. ANY PRECIPITATION SHOULD REMAIN NORTHWEST OF THE REGION...BUT MID AND HIGH LEVEL CLOUDINESS WILL LIKELY SPILL INTO THE AREA. NEXT WEATHER SYSTEM WILL IMPACT THE AREA LATE MONDAY INTO TUESDAY... WITH PRECIPITATION TYPE THE MAIN CONCERN. 18/18Z AND 19/00Z GFS AND 19/00Z ECMWF OPERATIONAL RUNS ARE VERY SIMILAR IN DEVELOPING SOUTHERLY FLOW ACROSS THE IMMEDIATE AREA AS THE SURFACE LOW TRACKS TO OUR NORTH TOWARDS CHICAGO BY 06Z TUESDAY. AS A RESULT... OPERATIONAL MOS GUIDANCE IS NOW FORECASTING HIGH TEMPERATURES IN THE 40S MONDAY...WITH READINGS NEAR FREEZING BY LATE MONDAY NIGHT. TO COMPLICATE MATTERS EVEN MORE...GFS FORECAST SOUNDINGS ARE NOT CONVINCING THAT ICE NUCLEATION WILL TAKE PLACE FOR SNOW CRYSTAL GROWTH GIVEN THE DRY AIR IN THE MID LEVELS. THE SCALES CERTAINLY SEEM TO BE WEIGHING MORE IN FAVOR OF LIQUID VERSUS FROZEN PRECIPITATION FOR MUCH OF THIS EVENT. HOWEVER...DEPENDING UPON THE AMOUNT OF DRY AIR IN THE BOUNDARY LAYER...THE ELEMENT OF EVAPORATIVE COOLING MAY ULTIMATELY BE THE DECIDING FACTOR. FOR NOW...WE TRENDED TOWARDS A SLIGHTLY WARMER SOLUTION BY STARTING THE EVENT OUT AS A MIX OF RAIN/SNOW NORTH...AND ALL RAIN SOUTH MONDAY EVENING. THEN TRANSITIONED TO ALL SNOW NORTH AND A MIX OF RAIN/SNOW SOUTH OVERNIGHT INTO TUESDAY. NONETHELESS...MODEL QPF FORECASTS ARE STILL RELATIVELY LIGHT...SO NOT A MAJOR EVENT AT THIS POINT. NO CHANGES WERE NECESSARY BEYOND TUESDAY. && .AVIATION... EXPECT A BAND OF MVFR CEILINGS (1500-2500 FT) TO MOVE ACROSS THE REGION THROUGH AROUND SUNRISE. VFR CONDITIONS SHOULD PREVAIL THE REMAINDER OF THE TAF PERIOD. ARCTIC FRONT IS NOW THROUGH ALL TAF SITES. EXPECT NW WINDS TO GUST TO AROUND 15 KTS TODAY...THEN DIE OUT THIS EVENING. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ RJP/GM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1057 PM EST SUN JAN 20 2008 .UPDATE...NEW UPDATE IS OUT AS THE SNOW BANDS CONTINUE TO DIMINISH DUE TO DRY AIR INTRUSION. SO HAVE DROPPED THE WINTER WEATHER ADVISORY AS THE SNOW AND BLOWING SNOW ISN`T LOWERING THE VISIBILITY SUBSTANTIALLY. LUTZ && .PREV DISCUSSION... /ISSUED 958 PM EST SUN JAN 20 2008/ UPDATE...SO FAR, THE FORECAST LOOKS LIKE IT IS DOING WELL WITH THE SNOW BANDS LOOKING LIKE THEY ARE BEGINNING TO TAPER OFF NEAR APN AND TVC. NEW NAM AND RUC LOOK TO BEAR OUT WHAT IS GOING ON IN N LOWER. E UPPER LOOKS LIKE IT WILL CONTINUE TO GET SNOW BANDS AFFECTING ANJ, WHITEFISH POINT, AND PARADISE. SO WILL LET THE WINTER WEATHER ADVISORY EXPIRE AT 11 PM AND WILL CONTINUE THE LES WARNING IN E UPPER. IT LOOKS LIKE THE 1000-850 MB STREAMLINES WILL BEGIN TO COME OUT OF THE SW, WHICH WILL BRING IN MORE DRY AIR. SO THE FORECAST LOOKS TO BE ON TRACK FOR NOW. ZONES WILL BE OUT CLOSER TO 11 PM TO LET THE WWA EXPIRE. LUTZ PREV DISCUSSION... /ISSUED 749 PM EST SUN JAN 20 2008/ AVIATION...ADJUSTED FOR THE SNOW BANDS AS THE WINDS REALIGN FOR THE NIGHT AND THE DAYTIME CONVECTION SETTLES DOWN. MAIN CONCERN OVER THE NEXT FEW HOURS WILL BE THE DRY AIR MOVING INTO THE REGION AND SUPPRESSING THE LAKE EFFECT SNOW SHOWERS. SO FAR, IT LOOKS LIKE THE DRY AIR WILL CAUSE THE SNOW SHOWERS AT TVC AND PLN TO TAPER OFF TO FLURRIES, AND STOP THE SNOW AT APN. CLOUD COVER WILL BE PROBLEMATIC WITH DRY AIR, YET SEEING WHERE THE CONVECTION CAN DRAW ON THE LAKE MOISTURE TO KEEP SOME CLOUDS. LUTZ PREV DISCUSSION... /ISSUED 333 PM EST SUN JAN 20 2008/ DISCUSSION...SUBSTANTIALLY DRIER AIR PRESSING ACROSS LAKE MICHIGAN (OUT OF THE WISCONSIN DEEP FREEZE) COUPLED WITH SOME DAYTIME "HEATING" HAS LEAD TO AN OVERALL DIMINISHING TREND TO THE LAKE EFFECT SNOWS (NOTE EASTWARD SHRINKING LAKE STCU). INLAND SNOW SHOWER COVERAGE HAS ACTUALLY EXPANDED A BIT WITH THE INLAND CONVECTIVE CYCLE...BUT MOST OF WHICH WILL FADE EARLY THIS EVENING. TO THE NORTH...OUTSIDE OF AREAS AROUND WHITEFISH BAY...NOT A BAD DAY IN THE EASTERN U.P. WITH QUITE A BIT OF SUNSHINE DESPITE THE VERY COLD TEMPS. FORECAST ISSUES TONIGHT REVOLVE AROUND DISPOSITION OF ONGOING WARNING AND ADVISORIES. TONIGHT...ACROSS NORTHERN LOWER MICHIGAN: W/WNW FLOW LOOKING TO REMAIN LOCKED THROUGHOUT THE NIGHT WITH MORE THAN AMPLE OVER WATER INSTABILITY. BUT MEANWHILE...VERY DRY UPSTREAM AIR (NEGATIVE TEEN DEWPOINTS IN WISCONSIN) WILL CONTINUE TO ADVECT EASTWARD ACROSS THE LAKE AND SHOULD KEEP OVERALL LAKE EFFECT INTENSITY IN CHECK. HIGH POPS FOR THE W/WNW FLOW AREAS ARE JUSTIFIED HOWEVER...GIVEN THE FANTASTIC OVER WATER INSTABILITY...BUT WILL LIMIT OVERALL ACCUMULATIONS TO UNDER 3 INCHES. AS FAR AS THE ADVISORY IS CONCERNED...CONSIDERED CANCELING THE HEADLINE GIVEN THE TRENDS IN THE LES INTENSITY. HOWEVER...WITH THE SMALL FLAKE SIZES AND GUSTY WINDS/BLSN VSBYS CONTINUE TO BE A PROBLEM THIS AFTERNOON AND WILL REMAIN AN ISSUE AT LEAST THROUGH EARLY-MID EVENING. SO...PLAN ON STRETCHING OUT THE ADVISORY FOR AREAS NORTH OF M-72 (WHERE MOST INTENSE SNOW SHOWERS NOW RESIDE) THROUGH THE EVENING HOURS...BUT FOCUS MORE ON THE LOW VSBYS AND WIND CHILL ASPECTS. WILL TRIM OUT GRAND TRAVERSE COUNTY OVER TO CRAWFORD COUNTY. EASTERN UPPER MICHIGAN: DIFFERENT PROBLEMS HERE. PER MONTREAL RIVER RADAR AND SATELLITE IMAGERY...FAIRLY HEFTY SNOW SHOWERS ONCE AGAIN IMPACTED THE WHITEFISH BAY AREA. 12Z NAM/GFS SOLUTIONS PEG BULLSEYE OF LOW LEVEL CONVERGENCE OVER THE SE CORNER OF THE LAKE/NRN CHIPPEWA COUNTY TONIGHT. AND GIVEN THE GREAT INSTABILITY/LONG FETCH LENGTHS...THINK AT LEAST ANOTHER 3-6 INCHES OF SNOW A GOOD BET FOR THAT AREA WITH BETTER SNOW SHOWER ACTIVITY IMPACTING AREAS EASTWARD INTO ANJ. GIVEN THIS...WILL STRETCH THE WARNING OUT FOR ANOTHER FORECAST PERIOD. ADAM MONDAY THROUGH TUESDAY...A COLD START TO MONDAY MORNING WITH PARTLY CLOUDY SKIES ACROSS MUCH OF NE LOWER...AND PORTIONS OF EASTERN UPPER. MID AND HIGH LEVEL CLOUDS WILL BE STREAMING IN AHEAD OF SHORTWAVE AND DEVELOPING TIGHT THERMAL GRADIENT/INVERTED TROUGH. SO EXPECT SKIES TO CLOUD UP QUICKLY. THE THERMAL GRADIENT LAYS OUT ACROSS NRN LOWER WITH MODEST 280-295K ISENTROPIC ASCENT AND MARGINAL FGEN RESPONSE FROM MAINLY MIDDAY MONDAY THROUGH MONDAY EVENING. BEST SYNOPTIC FORCING...MAINLY DUE TO WARM ADVECTION WILL BE ACROSS SRN WISCONSIN...BUT THIS FORCING ALONE WILL BRING A GOOD 2-3 INCHES ACROSS NRN LOWER. AIR MASS WILL BE MODERATING THROUGH THE EVENING...WITH THE REAL COLD H8 TEMPS WARMING TO FAVORABLE -14C TO -18C RANGE AT THE ONSET AND FOR THE DURATION OF THE SYNOPTIC SNOWFALL. THE KEY HERE WILL BE THE ADDITION OR ENHANCEMENT FROM THE LAKES. FAVORABLE H8 REGIME WITH BOUNTIFUL ICE CRYSTALS IN CLOUD TOP LAYER SHOULD RESULT IN LARGE FLAKES...POSSIBLY MANY...FOR A PERIOD INTO MONDAY EVENING. TROUGH SLIPS BY TUES AND H8 TEMPS COOL TO A STILL RESPECTABLE -18C/-19C. THUS...FAVORABLE THERMODYNAMICS THROUGH THE PERIOD...WITH DEEP MOISTURE AND FORCING...WHILE INVERSION HEIGHTS AVERAGE 6KFT WHEN USING PARCELS OFF THE LAKE. THE LAKES ALONE SUGGEST MODERATE ACCUMULATIONS. WHEN ADDED TO THE SYNOPTIC SNOWS...THE POTENTIAL IS THERE FOR HEAVY TOTAL SNOWFALL. THE QUESTION THAT NEEDS TO BE ANSWERED WILL BE THE 1000-850MB WIND DIRECTION. GFS HAS PROLONGED SW (230-240) FLOW WHILE NAM SHIFTS SW WINDS TO DUE SOUTH BY MONDAY EVENING. THIS DIFFERENCE MEANS WAY TOO MUCH TO PIN DOWN A PARTICULAR AREA. THEREFORE...AFTER MUCH COORDINATION...WILL ISSUE A WINTER STORM WATCH FOR MAINLY SW FLOW REGIMES. A SECONDARY SHORTWAVE DIVES INTO THE REGION TUESDAY WITH A SHOT OF DEEPER MOISTURE...WHILE 1000-850MB WINDS ARE SHIFTING WEST THEN NW. GOOD CYCLONIC CONVERGENCE IN PLACE AND INVERSION HEIGHTS STEEPEN TO A DEEP 8-9KFT POSSIBLY. THOUGHT ABOUT ISSUING A WATCH TO INCLUDE ALL OF THE NW FLOW REGIMES...BUT MIDNIGHT CREW HAS TIME TO LOOK AT THIS. IT DOES LOOK LIKE SNOWS COULD START COMING DOWN HARD TUESDAY AFTERNOON. HIGH WILL BE IN THE TEENS MONDAY AND TUESDAY...WITH LOWS MONDAY NIGHT NOT DIPPING TOO FAR FROM THE TEENS. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...STEEP INVERSION HEIGHTS DROP TO A RESPECTABLE 5-6KFT...WHILE WEAK MID LEVEL RIDGING MOVES IN. DEEPER MOISTURE STRIPS OUT ALOFT WHILE SFC HIGH PRESSURE TRIED TO POKE ACROSS THE NRN OHIO VALLEY. WE LOSE THE CYCLONIC CONVERGENCE...AND H8 TEMPS CONTINUE TO COOL TO THE LOWER -20S. THERE ARE TOO MANY INCONSISTENCIES BETWEEN THE MODELS ON KEY LES PARAMETERS...BUT THERE IS POTENTIAL FOR HEAVY SNOW INTO AT LEAST TUESDAY EVENING FOR WNW/NW FLOW REGIMES. SHOULD SEE FLAKE SIZES GET PROGRESSIVELY SMALLER WITH TIME. THESE DETAILS WILL BECOME CLEARER OVER THE NEXT COUPLE OF DAYS. YET ANOTHER SHOT OF COLDER AIR ARRIVES BY WEDNESDAY NIGHT...AS ONE MORE SHORTWAVE AND ASSOCIATED SFC LOW WORKS INTO NRN MICHIGAN. THIS COULD SPELL ANOTHER PERIOD OF SYNOPTIC SNOWS ENHANCED BY THE LAKES. WILL HAVE TO WAIT AND SEE WITH THIS ONE. ALL-IN-ALL...SOME AREAS COULD BE INVOLVED IN A PROLONGED PERIOD OF SNOWFALL. OBVIOUSLY...HEADLINES WILL BE THE MAJOR ISSUE WITH TIME. HIGHS WEDNESDAY COOL DOWN TO THE 6-14 RANGE WHILE LOWS WILL BE IN THE SINGLE DIGITS BOTH ABOVE AND BELOW ZERO. THURSDAY ONWARD...SCATTERED LAKE EFFECT SNOW SHOWERS THURSDAY LOOK TO COME TO AN END FRIDAY WITH A GRADUAL WARMING OF THE BL AND POSSIBLE END TO SUFFICIENT OVERLAKE INSTABILITY. WILL HAVE TO SEE ON THIS...BUT SFC HIGH PRESSURE AND DRY AIR SLIDE ACROSS THE OHIO RIVER VALLEY WITH OUR H8 TEMPS WARMING TO -8C OR SO. LEFT SOME RESIDUAL SNOW SHOWERS IN NW FLOW REGIME THURSDAY...THEN SW THURSDAY NIGHT. A DRY FRIDAY FOR NOW...BEFORE NEXT SHORTWAVE/FRONT ARRIVES FRIDAY NIGHT INTO NEXT WEEKEND FOR CHANCE OF SNOW. SMD AVIATION...ISSUED AT 111 PM. MVFR CIGS/VSBYS CONTINUE AT PLN/TVC INTO EARLY EVENING DUE TO CONTINUING LAKE EFFECT SNOW SHOWERS. SCATTERED SNOW SHOWERS WITH OCCASIONALLY REDUCED VSBYS THIS AFTERNOON AT APN. SNOW SHOWER ACTIVITY EXPECTED TO DIMINISH THIS EVENING AND OVERNIGHT WITH IMPROVEMENT TO VFR CONDITIONS. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON FOR MIZ015-016-019>021-025-026-031-032. LAKE EFFECT SNOW WARNING UNTIL 5 AM EST MONDAY FOR MIZ008. LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ323-341-342- 344>346. LH...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LHZ345>349. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 958 PM EST SUN JAN 20 2008 .UPDATE...SO FAR, THE FORECAST LOOKS LIKE IT IS DOING WELL WITH THE SNOW BANDS LOOKING LIKE THEY ARE BEGINNING TO TAPER OFF NEAR APN AND TVC. NEW NAM AND RUC LOOK TO BEAR OUT WHAT IS GOING ON IN N LOWER. E UPPER LOOKS LIKE IT WILL CONTINUE TO GET SNOW BANDS AFFECTING ANJ, WHITEFISH POINT, AND PARADISE. SO WILL LET THE WINTER WEATHER ADVISORY EXPIRE AT 11 PM AND WILL CONTINUE THE LES WARNING IN E UPPER. IT LOOKS LIKE THE 1000-850 MB STREAMLINES WILL BEGIN TO COME OUT OF THE SW, WHICH WILL BRING IN MORE DRY AIR. SO THE FORECAST LOOKS TO BE ON TRACK FOR NOW. ZONES WILL BE OUT CLOSER TO 11 PM TO LET THE WWA EXPIRE. LUTZ && .PREV DISCUSSION... /ISSUED 749 PM EST SUN JAN 20 2008/ AVIATION...ADJUSTED FOR THE SNOW BANDS AS THE WINDS REALIGN FOR THE NIGHT AND THE DAYTIME CONVECTION SETTLES DOWN. MAIN CONCERN OVER THE NEXT FEW HOURS WILL BE THE DRY AIR MOVING INTO THE REGION AND SUPPRESSING THE LAKE EFFECT SNOW SHOWERS. SO FAR, IT LOOKS LIKE THE DRY AIR WILL CAUSE THE SNOW SHOWERS AT TVC AND PLN TO TAPER OFF TO FLURRIES, AND STOP THE SNOW AT APN. CLOUD COVER WILL BE PROBLEMATIC WITH DRY AIR, YET SEEING WHERE THE CONVECTION CAN DRAW ON THE LAKE MOISTURE TO KEEP SOME CLOUDS. LUTZ PREV DISCUSSION... /ISSUED 333 PM EST SUN JAN 20 2008/ DISCUSSION...SUBSTANTIALLY DRIER AIR PRESSING ACROSS LAKE MICHIGAN (OUT OF THE WISCONSIN DEEP FREEZE) COUPLED WITH SOME DAYTIME "HEATING" HAS LEAD TO AN OVERALL DIMINISHING TREND TO THE LAKE EFFECT SNOWS (NOTE EASTWARD SHRINKING LAKE STCU). INLAND SNOW SHOWER COVERAGE HAS ACTUALLY EXPANDED A BIT WITH THE INLAND CONVECTIVE CYCLE...BUT MOST OF WHICH WILL FADE EARLY THIS EVENING. TO THE NORTH...OUTSIDE OF AREAS AROUND WHITEFISH BAY...NOT A BAD DAY IN THE EASTERN U.P. WITH QUITE A BIT OF SUNSHINE DESPITE THE VERY COLD TEMPS. FORECAST ISSUES TONIGHT REVOLVE AROUND DISPOSITION OF ONGOING WARNING AND ADVISORIES. TONIGHT...ACROSS NORTHERN LOWER MICHIGAN: W/WNW FLOW LOOKING TO REMAIN LOCKED THROUGHOUT THE NIGHT WITH MORE THAN AMPLE OVER WATER INSTABILITY. BUT MEANWHILE...VERY DRY UPSTREAM AIR (NEGATIVE TEEN DEWPOINTS IN WISCONSIN) WILL CONTINUE TO ADVECT EASTWARD ACROSS THE LAKE AND SHOULD KEEP OVERALL LAKE EFFECT INTENSITY IN CHECK. HIGH POPS FOR THE W/WNW FLOW AREAS ARE JUSTIFIED HOWEVER...GIVEN THE FANTASTIC OVER WATER INSTABILITY...BUT WILL LIMIT OVERALL ACCUMULATIONS TO UNDER 3 INCHES. AS FAR AS THE ADVISORY IS CONCERNED...CONSIDERED CANCELING THE HEADLINE GIVEN THE TRENDS IN THE LES INTENSITY. HOWEVER...WITH THE SMALL FLAKE SIZES AND GUSTY WINDS/BLSN VSBYS CONTINUE TO BE A PROBLEM THIS AFTERNOON AND WILL REMAIN AN ISSUE AT LEAST THROUGH EARLY-MID EVENING. SO...PLAN ON STRETCHING OUT THE ADVISORY FOR AREAS NORTH OF M-72 (WHERE MOST INTENSE SNOW SHOWERS NOW RESIDE) THROUGH THE EVENING HOURS...BUT FOCUS MORE ON THE LOW VSBYS AND WIND CHILL ASPECTS. WILL TRIM OUT GRAND TRAVERSE COUNTY OVER TO CRAWFORD COUNTY. EASTERN UPPER MICHIGAN: DIFFERENT PROBLEMS HERE. PER MONTREAL RIVER RADAR AND SATELLITE IMAGERY...FAIRLY HEFTY SNOW SHOWERS ONCE AGAIN IMPACTED THE WHITEFISH BAY AREA. 12Z NAM/GFS SOLUTIONS PEG BULLSEYE OF LOW LEVEL CONVERGENCE OVER THE SE CORNER OF THE LAKE/NRN CHIPPEWA COUNTY TONIGHT. AND GIVEN THE GREAT INSTABILITY/LONG FETCH LENGTHS...THINK AT LEAST ANOTHER 3-6 INCHES OF SNOW A GOOD BET FOR THAT AREA WITH BETTER SNOW SHOWER ACTIVITY IMPACTING AREAS EASTWARD INTO ANJ. GIVEN THIS...WILL STRETCH THE WARNING OUT FOR ANOTHER FORECAST PERIOD. ADAM MONDAY THROUGH TUESDAY...A COLD START TO MONDAY MORNING WITH PARTLY CLOUDY SKIES ACROSS MUCH OF NE LOWER...AND PORTIONS OF EASTERN UPPER. MID AND HIGH LEVEL CLOUDS WILL BE STREAMING IN AHEAD OF SHORTWAVE AND DEVELOPING TIGHT THERMAL GRADIENT/INVERTED TROUGH. SO EXPECT SKIES TO CLOUD UP QUICKLY. THE THERMAL GRADIENT LAYS OUT ACROSS NRN LOWER WITH MODEST 280-295K ISENTROPIC ASCENT AND MARGINAL FGEN RESPONSE FROM MAINLY MIDDAY MONDAY THROUGH MONDAY EVENING. BEST SYNOPTIC FORCING...MAINLY DUE TO WARM ADVECTION WILL BE ACROSS SRN WISCONSIN...BUT THIS FORCING ALONE WILL BRING A GOOD 2-3 INCHES ACROSS NRN LOWER. AIR MASS WILL BE MODERATING THROUGH THE EVENING...WITH THE REAL COLD H8 TEMPS WARMING TO FAVORABLE -14C TO -18C RANGE AT THE ONSET AND FOR THE DURATION OF THE SYNOPTIC SNOWFALL. THE KEY HERE WILL BE THE ADDITION OR ENHANCEMENT FROM THE LAKES. FAVORABLE H8 REGIME WITH BOUNTIFUL ICE CRYSTALS IN CLOUD TOP LAYER SHOULD RESULT IN LARGE FLAKES...POSSIBLY MANY...FOR A PERIOD INTO MONDAY EVENING. TROUGH SLIPS BY TUES AND H8 TEMPS COOL TO A STILL RESPECTABLE -18C/-19C. THUS...FAVORABLE THERMODYNAMICS THROUGH THE PERIOD...WITH DEEP MOISTURE AND FORCING...WHILE INVERSION HEIGHTS AVERAGE 6KFT WHEN USING PARCELS OFF THE LAKE. THE LAKES ALONE SUGGEST MODERATE ACCUMULATIONS. WHEN ADDED TO THE SYNOPTIC SNOWS...THE POTENTIAL IS THERE FOR HEAVY TOTAL SNOWFALL. THE QUESTION THAT NEEDS TO BE ANSWERED WILL BE THE 1000-850MB WIND DIRECTION. GFS HAS PROLONGED SW (230-240) FLOW WHILE NAM SHIFTS SW WINDS TO DUE SOUTH BY MONDAY EVENING. THIS DIFFERENCE MEANS WAY TOO MUCH TO PIN DOWN A PARTICULAR AREA. THEREFORE...AFTER MUCH COORDINATION...WILL ISSUE A WINTER STORM WATCH FOR MAINLY SW FLOW REGIMES. A SECONDARY SHORTWAVE DIVES INTO THE REGION TUESDAY WITH A SHOT OF DEEPER MOISTURE...WHILE 1000-850MB WINDS ARE SHIFTING WEST THEN NW. GOOD CYCLONIC CONVERGENCE IN PLACE AND INVERSION HEIGHTS STEEPEN TO A DEEP 8-9KFT POSSIBLY. THOUGHT ABOUT ISSUING A WATCH TO INCLUDE ALL OF THE NW FLOW REGIMES...BUT MIDNIGHT CREW HAS TIME TO LOOK AT THIS. IT DOES LOOK LIKE SNOWS COULD START COMING DOWN HARD TUESDAY AFTERNOON. HIGH WILL BE IN THE TEENS MONDAY AND TUESDAY...WITH LOWS MONDAY NIGHT NOT DIPPING TOO FAR FROM THE TEENS. TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...STEEP INVERSION HEIGHTS DROP TO A RESPECTABLE 5-6KFT...WHILE WEAK MID LEVEL RIDGING MOVES IN. DEEPER MOISTURE STRIPS OUT ALOFT WHILE SFC HIGH PRESSURE TRIED TO POKE ACROSS THE NRN OHIO VALLEY. WE LOSE THE CYCLONIC CONVERGENCE...AND H8 TEMPS CONTINUE TO COOL TO THE LOWER -20S. THERE ARE TOO MANY INCONSISTENCIES BETWEEN THE MODELS ON KEY LES PARAMETERS...BUT THERE IS POTENTIAL FOR HEAVY SNOW INTO AT LEAST TUESDAY EVENING FOR WNW/NW FLOW REGIMES. SHOULD SEE FLAKE SIZES GET PROGRESSIVELY SMALLER WITH TIME. THESE DETAILS WILL BECOME CLEARER OVER THE NEXT COUPLE OF DAYS. YET ANOTHER SHOT OF COLDER AIR ARRIVES BY WEDNESDAY NIGHT...AS ONE MORE SHORTWAVE AND ASSOCIATED SFC LOW WORKS INTO NRN MICHIGAN. THIS COULD SPELL ANOTHER PERIOD OF SYNOPTIC SNOWS ENHANCED BY THE LAKES. WILL HAVE TO WAIT AND SEE WITH THIS ONE. ALL-IN-ALL...SOME AREAS COULD BE INVOLVED IN A PROLONGED PERIOD OF SNOWFALL. OBVIOUSLY...HEADLINES WILL BE THE MAJOR ISSUE WITH TIME. HIGHS WEDNESDAY COOL DOWN TO THE 6-14 RANGE WHILE LOWS WILL BE IN THE SINGLE DIGITS BOTH ABOVE AND BELOW ZERO. THURSDAY ONWARD...SCATTERED LAKE EFFECT SNOW SHOWERS THURSDAY LOOK TO COME TO AN END FRIDAY WITH A GRADUAL WARMING OF THE BL AND POSSIBLE END TO SUFFICIENT OVERLAKE INSTABILITY. WILL HAVE TO SEE ON THIS...BUT SFC HIGH PRESSURE AND DRY AIR SLIDE ACROSS THE OHIO RIVER VALLEY WITH OUR H8 TEMPS WARMING TO -8C OR SO. LEFT SOME RESIDUAL SNOW SHOWERS IN NW FLOW REGIME THURSDAY...THEN SW THURSDAY NIGHT. A DRY FRIDAY FOR NOW...BEFORE NEXT SHORTWAVE/FRONT ARRIVES FRIDAY NIGHT INTO NEXT WEEKEND FOR CHANCE OF SNOW. SMD AVIATION...ISSUED AT 111 PM. MVFR CIGS/VSBYS CONTINUE AT PLN/TVC INTO EARLY EVENING DUE TO CONTINUING LAKE EFFECT SNOW SHOWERS. SCATTERED SNOW SHOWERS WITH OCCASIONALLY REDUCED VSBYS THIS AFTERNOON AT APN. SNOW SHOWER ACTIVITY EXPECTED TO DIMINISH THIS EVENING AND OVERNIGHT WITH IMPROVEMENT TO VFR CONDITIONS. ADAM && .APX WATCHES/WARNINGS/ADVISORIES... MI...WINTER STORM WATCH FROM MONDAY MORNING THROUGH TUESDAY AFTERNOON FOR MIZ015-016-019>021-025-026-031-032. WINTER WEATHER ADVISORY UNTIL 11 PM EST THIS EVENING FOR MIZ016- 017-019-021-022. LAKE EFFECT SNOW WARNING UNTIL 5 AM EST MONDAY FOR MIZ008. LM...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LMZ323-341-342- 344>346. LH...SMALL CRAFT ADVISORY UNTIL 7 AM EST MONDAY FOR LHZ345>349. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 825 PM EST SUN JAN 20 2008 .UPDATE... LES CONTINUES TO STREAM INTO THE ERN COUNTIES E OF P53 IN COLD WNW FLOW ACRS LK SUP. SPOTTER REPORTS INDICATE THE LES IS NO LONGER PARTICULARLY HVY...SO ALLOWED LES WRNG FOR ALGER/LUCE ZNS TO EXPIRE AS SCHEDULED AT 00Z. HOWEVER...WINDS AT GRAND MARAIS HAVE BEEN 30-35 MPH ALL EVNG...SO POSTED AN LES/BLSN ADVY FOR ALGER/LUCE THRU THE NGT WITH SEVERAL MORE INCHES OF FINE SNOW LIKELY. WITH BACKING LLVL FLOW ENHANCED BY LAND BREEZE COMPONENT...THE SHSN WL CONTINUE TO GRDLY SHIFT TO THE N AND IMPACT ONLY AREAS NEAR THE SHORELINE BY LATE NGT. SINCE SHSN HAVE BEEN LIFTING SLOWLY TO THE N...DID NOT EXTEND THE LES ADVY FOR NRN SCHOOLCRAFT. OTRW... OTHER LES/WIND CHILLS HEADLINES SEEM ON TRACK EVEN THOUGH THERE IS SOME QUESTION AS TO WHETHER WIND SPEEDS WL BE HI ENUF AT MOST PLACES WHERE WIND CHILL ADVYS ARE IN EFFECT. BUT EVEN IF WIND SPEEDS DO NOT MEET THE THRESHOLD REQUIREMENT...THE APRNT TEMP WL STILL BE LO ENUF TO JUSTIFY KEEPING THE HEADLINES. .SHORT TERM... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR LAKE EFFECT SNOWS TONIGHT AND THE NEXT SYSTEM APPROACHING FROM THE SOUTH ON MONDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA. A CLOSED LOW CONTINUES TO DEVELOP OVER IDAHO. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE ARE OVER WISCONSIN AND EASTERN U.P. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL ILLINOIS WITH THE ACCOMPANYING RIDGE STRETCHING NORTHWEST ACROSS THE NORTHERN PLAINS INTO ALBERTA. A WEAK SURFACE TROUGH IS OVER EASTERN LAKE SUPERIOR. AN 850MB THERMAL TROUGH CONTINUES TO SHIFT EAST...WITH THE LAKE-850MB DELTA-T OF AROUND 28C THIS IS GENERATING WEAK LOW LEVEL CONVERGENCE AND INSTABILITY. THE LOW LEVEL AIR MASS IS STILL VERY DRY...WITH THE PRECIPITABLE WATER OF LESS THAN .1 OF AN INCH. LAKE EFFECT SNOWS CONTINUE OVER THE COUNTIES ADJACENT TO THE LAKE AND DOWNWIND OF WEST TO NORTHWEST WINDS. THE LONGWAVE TROUGH WILL SHIFT EAST INTO THE CANADIAN MARITIME. AS THE CLOSED LOW OVER IDAHO DEEPENS. A RIDGE WILL BE CLIMBING ASHORE OVER SOUTHWEST CANADA. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE WILL MOVE INTO EASTERN AND CENTRAL ONTARIO TONIGHT AND SET UP KIND OF A ZONAL FLOW ACROSS THE CENTRAL CONUS. MID LEVEL WINDS WILL BACK A LITTLE MORE WEST OVER THE AREA TONIGHT. THE SURFACE HIGH WILL SHIFT TO EASTERN OHIO RIVER VALLEY. LOW LEVEL CONVERGENCE ALONG THE LAKE SHORE WILL KEEP SOME LAKE EFFECTS SNOWS GOING IN THAT AREA. SPOTTER REPORTS INDICATE THAT THE SNOW IS VERY FINE AND NOT MUCH ACCUMULATION TAKING PLACE OVER NORTHERN ALGER AND LUCE COUNTIES. HOWEVER...WINDS CONTINUE TO BE STRONG THIS AFTERNOON. GUIDANCE SHOW AS THE HIGH MOVES EAST TONIGHT...PRESSURE GRADIENTS OVER THE AREA WILL WEAKEN AND WIND WILL TAPER OFF. THIS SHOULD CAUSE THE BLOWING SNOW TO DIMINISH BY LATE EVENING. RADIATIONAL COOLING WILL CAUSE TEMPERATURES TO DROP TO -20C. WINDS WILL BE TOO LIGHT TO QUALIFY FOR WIND CHILL ADVISORY EXCEPT THIS EVENING. THE LOW OVER THE PACIFIC NORTHWEST WILL SLIDE DOWN THE COAST INTO NORTHERN CALIFORNIA. AN ACCOMPANYING MID LEVEL TROUGH WILL SHIFT INTO THE NORTHERN PLAINS...KEEPING ZONAL FLOW ACROSS THE CONUS. THE LAKE INDUCED SURFACE LOW WILL DEVELOP OVER EASTERN LAKE SUPERIOR ON MONDAY. A SURFACE LOW WILL SLIDE OUT OF THE CENTRAL PLAINS INTO NORTHERN MISSOURI ON MONDAY. WITH THE APPROACH OF THE LOW...GUIDANCE SHOWING A WEAK INSTABILITY AND MOISTURE WORKING NORTH INTO THE SOUTHERN PART OF THE FORECAST AREA. WILL KEEP A SLIGHT CHANCE GOING FOR THE SOUTHERN COUNTIES MONDAY AFTERNOON. 850MB TEMPERATURES WILL KEEP SOME LAKE EFFECT SNOWS GOING INTO THE AFTERNOON. && .LONG TERM (MON NIGHT INTO TUE)... MON NIGHT INTO TUE...SHRTWV MOVING DOWN THROUGH THE NRN MN AND THE DAKOTAS IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING... MAINTAINING THE COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP PROPEL SYSTEM OVER ERN KANSAS NORTHEAST THROUGH LOWER MICHIGAN DURING THIS PERIOD. KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE LAKE MICHIGAN SHORELINE AS GFS STILL INDICATES MID-LVL FRONTOGENETICAL FORCING AND BOTH GFS/UKMET BRING SOME LIGHT PCPN INTO THE ERN CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW. WINDS REMAIN MOSTLY WESTERLY MON NIGHT FAVORING PERHAPS A MAIN CONVERGENT BAND OVER NORTHERN HOUGHTON COUNTY. BY TUE AFTERNOON... WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. THIS SLIGHT VEERING OF WINDS SHOULD BRING LES BACK INTO ONTONAGON COUNTY UP THROUGH THE KEWEENAW SO WILL MAINTAIN LIKELY POPS FOR THESE AREAS. RAISED TEMPS A FEW MORE DEGREES MONDAY NIGHT AS CLOUD COVER FROM SYSTEM MOVING THROUGH LOWER MIDWEST SHOULD KEEP TEMPS UP...ALTHOUGH STILL EXPECT SINGLE DIGITS BLO ZERO OVER THE WRN INTERIOR. TUE HIGH TEMPS SHOULD BE FAIRLY SIMILAR TO MON. TUE NIGHT INTO WED...MODELS SHOW POTENT SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA TUE EVENING INTO THE UPPER GREAT LAKES. GFS/UKMET/ECMWF PROG 850MB TEMPS TO BE -25 TO -28C ACROSS UPPER MI BY WED MORNING IN THE WAKE OF THE SHORTWAVE. THE SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH WILL INTENSIFY THE LOW LEVEL CONVERGENCE OVER THE KEWEENAW PENINSULA AND THE ERN COUNTIES TUE NIGHT INTO WED. LIKELY POPS STILL ON TARGET FOR FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING IN...HIGH TEMPS AGAIN MAY STRUGGLE TO REACH ABV ZERO ON WED. ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA BY THU...WHICH SHOULD HELP MODERATE TEMPS. THIS WARMING IN TANDEM WITH FLOW BACKING MORE WRLY SHOULD HELP TAPER LES TO FLURRIES OVER THE KEWEENAW PENINSULA AND ERN SHORELINE OF THE CWA. EXPECT DRY CONDITIONS THU NIGHT INTO FRI AS BOTH THE OPERATIONAL GFS AND ECMWF INDICATE RIDGING OVER THE AREA. AGREEMENT OF THE OPERATIONAL RUNS WITH THE GFS ENSEMBLE MEAN ALSO INCREASES CONFIDENCE IN KEEPING THIS PERIOD DRY. ARRIVAL OF ANOTHER SHORTWAVE TROF FOR THE FRI NIGHT INTO SAT TIME FRAME PER ECMWF AND GFS WILL WARRANT CHC POPS FOR SNOW ACROSS THE CWA. SHIFT TO NWRLY WINDS SAT NIGHT INTO SUN BEHIND FRONTAL SYSTEM SHOULD KEEP SOME LES AROUND FOR THE NRN AND ERN COUNTIES WHILE ISOLATED SNOW SHOWERS OR FLURRIES CAN BE EXPECTED FURTHER SOUTH. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... LES/GENERALLY IFR/LIFR VSBYS AND MVFR/OCNL IFR CIGS WL CONTINUE AT CMX TNGT BEFORE ARRIVAL OF DRIER AIR SHOWN ON TAMDAR SDNGS FM DLH/YQT AND SLOWLY BACKING LLVL FLOW CONSPIRE TO AT LEAST DIMINISH THE LES AND RESULT IN SOME IMPROVEMENT LATE TNGT AND MON MRNG AS LK INDUCED TROF LOOKS TO SET UP JUST N OF CMX. PASSAGE OF DISTURBANCE TO THE S WITH VEERING FLOW TO MORE WNW AGAIN LATER ON MON WL LIKELY SHIFT THE TROF S AGAIN PAST CMX...WITH THE SITE EXPERIENCING DETERIORATING CONDITIONS LATER ON MON AFTN. SINCE SAW WL BE ON THE S SIDE OF THE LK INDUCED TROF AND UNDER THE DOMINATION OF DRY... CONTINENTAL ARCTIC AIR...EXPECT VFR CONDITIONS THERE THRU THE PD. BUT THERE WL BE AN INCRS IN HI/MID CLDS STARTING LATE TNGT THERE COINCIDENT WITH THE PASSAGE OF THE DISTURBANCE TO THE S. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NORTHWEST WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE LOWER GREAT LAKES AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN...LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003. WIND CHILL ADVISORY UNTIL 11 AM EST /10 AM CST/ MONDAY FOR MIZ002-004-005-009>011-084. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 5 AM EST MONDAY FOR MIZ006-007. LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY FOR LSZ263>267. LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248- 250. && $$ UPDATE...KC SHORT TERM...DLG LONG TERM...VOSS AVIATION...KC MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 630 PM EST SUN JAN 20 2008 UPDATED FOR AVIATION .SHORT TERM... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR LAKE EFFECT SNOWS TONIGHT AND THE NEXT SYSTEM APPROACHING FROM THE SOUTH ON MONDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA. A CLOSED LOW CONTINUES TO DEVELOP OVER IDAHO. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE ARE OVER WISCONSIN AND EASTERN U.P. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL ILLINOIS WITH THE ACCOMPANYING RIDGE STRETCHING NORTHWEST ACROSS THE NORTHERN PLAINS INTO ALBERTA. A WEAK SURFACE TROUGH IS OVER EASTERN LAKE SUPERIOR. AN 850MB THERMAL TROUGH CONTINUES TO SHIFT EAST...WITH THE LAKE-850MB DELTA-T OF AROUND 28C THIS IS GENERATING WEAK LOW LEVEL CONVERGENCE AND INSTABILITY. THE LOW LEVEL AIR MASS IS STILL VERY DRY...WITH THE PRECIPITABLE WATER OF LESS THAN .1 OF AN INCH. LAKE EFFECT SNOWS CONTINUE OVER THE COUNTIES ADJACENT TO THE LAKE AND DOWNWIND OF WEST TO NORTHWEST WINDS. THE LONGWAVE TROUGH WILL SHIFT EAST INTO THE CANADIAN MARITIME. AS THE CLOSED LOW OVER IDAHO DEEPENS. A RIDGE WILL BE CLIMBING ASHORE OVER SOUTHWEST CANADA. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE WILL MOVE INTO EASTERN AND CENTRAL ONTARIO TONIGHT AND SET UP KIND OF A ZONAL FLOW ACROSS THE CENTRAL CONUS. MID LEVEL WINDS WILL BACK A LITTLE MORE WEST OVER THE AREA TONIGHT. THE SURFACE HIGH WILL SHIFT TO EASTERN OHIO RIVER VALLEY. LOW LEVEL CONVERGENCE ALONG THE LAKE SHORE WILL KEEP SOME LAKE EFFECTS SNOWS GOING IN THAT AREA. SPOTTER REPORTS INDICATE THAT THE SNOW IS VERY FINE AND NOT MUCH ACCUMULATION TAKING PLACE OVER NORTHERN ALGER AND LUCE COUNTIES. HOWEVER...WINDS CONTINUE TO BE STRONG THIS AFTERNOON. GUIDANCE SHOW AS THE HIGH MOVES EAST TONIGHT...PRESSURE GRADIENTS OVER THE AREA WILL WEAKEN AND WIND WILL TAPER OFF. THIS SHOULD CAUSE THE BLOWING SNOW TO DIMINISH BY LATE EVENING. RADIATIONAL COOLING WILL CAUSE TEMPERATURES TO DROP TO -20C. WINDS WILL BE TOO LIGHT TO QUALIFY FOR WIND CHILL ADVISORY EXCEPT THIS EVENING. THE LOW OVER THE PACIFIC NORTHWEST WILL SLIDE DOWN THE COAST INTO NORTHERN CALIFORNIA. AN ACCOMPANYING MID LEVEL TROUGH WILL SHIFT INTO THE NORTHERN PLAINS...KEEPING ZONAL FLOW ACROSS THE CONUS. THE LAKE INDUCED SURFACE LOW WILL DEVELOP OVER EASTERN LAKE SUPERIOR ON MONDAY. A SURFACE LOW WILL SLIDE OUT OF THE CENTRAL PLAINS INTO NORTHERN MISSOURI ON MONDAY. WITH THE APPROACH OF THE LOW...GUIDANCE SHOWING A WEAK INSTABILITY AND MOISTURE WORKING NORTH INTO THE SOUTHERN PART OF THE FORECAST AREA. WILL KEEP A SLIGHT CHANCE GOING FOR THE SOUTHERN COUNTIES MONDAY AFTERNOON. 850MB TEMPERATURES WILL KEEP SOME LAKE EFFECT SNOWS GOING INTO THE AFTERNOON. && .LONG TERM (MON NIGHT INTO TUE)... MON NIGHT INTO TUE...SHRTWV MOVING DOWN THROUGH THE NRN MN AND THE DAKOTAS IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING... MAINTAINING THE COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP PROPEL SYSTEM OVER ERN KANSAS NORTHEAST THROUGH LOWER MICHIGAN DURING THIS PERIOD. KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE LAKE MICHIGAN SHORELINE AS GFS STILL INDICATES MID-LVL FRONTOGENETICAL FORCING AND BOTH GFS/UKMET BRING SOME LIGHT PCPN INTO THE ERN CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW. WINDS REMAIN MOSTLY WESTERLY MON NIGHT FAVORING PERHAPS A MAIN CONVERGENT BAND OVER NORTHERN HOUGHTON COUNTY. BY TUE AFTERNOON... WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. THIS SLIGHT VEERING OF WINDS SHOULD BRING LES BACK INTO ONTONAGON COUNTY UP THROUGH THE KEWEENAW SO WILL MAINTAIN LIKELY POPS FOR THESE AREAS. RAISED TEMPS A FEW MORE DEGREES MONDAY NIGHT AS CLOUD COVER FROM SYSTEM MOVING THROUGH LOWER MIDWEST SHOULD KEEP TEMPS UP...ALTHOUGH STILL EXPECT SINGLE DIGITS BLO ZERO OVER THE WRN INTERIOR. TUE HIGH TEMPS SHOULD BE FAIRLY SIMILAR TO MON. TUE NIGHT INTO WED...MODELS SHOW POTENT SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA TUE EVENING INTO THE UPPER GREAT LAKES. GFS/UKMET/ECMWF PROG 850MB TEMPS TO BE -25 TO -28C ACROSS UPPER MI BY WED MORNING IN THE WAKE OF THE SHORTWAVE. THE SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH WILL INTENSIFY THE LOW LEVEL CONVERGENCE OVER THE KEWEENAW PENINSULA AND THE ERN COUNTIES TUE NIGHT INTO WED. LIKELY POPS STILL ON TARGET FOR FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING IN...HIGH TEMPS AGAIN MAY STRUGGLE TO REACH ABV ZERO ON WED. ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA BY THU...WHICH SHOULD HELP MODERATE TEMPS. THIS WARMING IN TANDEM WITH FLOW BACKING MORE WRLY SHOULD HELP TAPER LES TO FLURRIES OVER THE KEWEENAW PENINSULA AND ERN SHORELINE OF THE CWA. EXPECT DRY CONDITIONS THU NIGHT INTO FRI AS BOTH THE OPERATIONAL GFS AND ECMWF INDICATE RIDGING OVER THE AREA. AGREEMENT OF THE OPERATIONAL RUNS WITH THE GFS ENSEMBLE MEAN ALSO INCREASES CONFIDENCE IN KEEPING THIS PERIOD DRY. ARRIVAL OF ANOTHER SHORTWAVE TROF FOR THE FRI NIGHT INTO SAT TIME FRAME PER ECMWF AND GFS WILL WARRANT CHC POPS FOR SNOW ACROSS THE CWA. SHIFT TO NWRLY WINDS SAT NIGHT INTO SUN BEHIND FRONTAL SYSTEM SHOULD KEEP SOME LES AROUND FOR THE NRN AND ERN COUNTIES WHILE ISOLATED SNOW SHOWERS OR FLURRIES CAN BE EXPECTED FURTHER SOUTH. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... LES/GENERALLY IFR/LIFR VSBYS AND MVFR/OCNL IFR CIGS WL CONTINUE AT CMX TNGT BEFORE ARRIVAL OF DRIER AIR SHOWN ON TAMDAR SDNGS FM DLH/YQT AND SLOWLY BACKING LLVL FLOW CONSPIRE TO AT LEAST DIMINISH THE LES AND RESULT IN SOME IMPROVEMENT LATE TNGT AND MON MRNG AS LK INDUCED TROF LOOKS TO SET UP JUST N OF CMX. PASSAGE OF DISTURBANCE TO THE S WITH VEERING FLOW TO MORE WNW AGAIN LATER ON MON WL LIKELY SHIFT THE TROF S AGAIN PAST CMX...WITH THE SITE EXPERIENCING DETERIORATING CONDITIONS LATER ON MON AFTN. SINCE SAW WL BE ON THE S SIDE OF THE LK INDUCED TROF AND UNDER THE DOMINATION OF DRY... CONTINENTAL ARCTIC AIR...EXPECT VFR CONDITIONS THERE THRU THE PD. BUT THERE WL BE AN INCRS IN HI/MID CLDS STARTING LATE TNGT THERE COINCIDENT WITH THE PASSAGE OF THE DISTURBANCE TO THE S. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NORTHWEST WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE LOWER GREAT LAKES AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN...LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003. WIND CHILL ADVISORY UNTIL 11 AM EST /10 AM CST/ MONDAY FOR MIZ002-004-005-009>011-084. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ006- 007. LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY FOR LSZ263>267. LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250. && $$ SHORT TERM...DLG LONG TERM...VOSS AVIATION...KC MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 411 PM EST SUN JAN 20 2008 .SHORT TERM... THE MAIN CONCERN WITH THIS FORECAST PACKAGE IS THE POTENTIAL FOR LAKE EFFECT SNOWS TONIGHT AND THE NEXT SYSTEM APPROACHING FROM THE SOUTH ON MONDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA. A CLOSED LOW CONTINUES TO DEVELOP OVER IDAHO. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE ARE OVER WISCONSIN AND EASTERN U.P. SURFACE ANALYSIS DEPICTS A LARGE HIGH OVER EAST CENTRAL ILLINOIS WITH THE ACCOMPANYING RIDGE STRETCHING NORTHWEST ACROSS THE NORTHERN PLAINS INTO ALBERTA. A WEAK SURFACE TROUGH IS OVER EASTERN LAKE SUPERIOR. AN 850MB THERMAL TROUGH CONTINUES TO SHIFT EAST...WITH THE LAKE-850MB DELTA-T OF AROUND 28C THIS IS GENERATING WEAK LOW LEVEL CONVERGENCE AND INSTABILITY. THE LOW LEVEL AIR MASS IS STILL VERY DRY...WITH THE PRECIPITABLE WATER OF LESS THAN .1 OF AN INCH. LAKE EFFECT SNOWS CONTINUE OVER THE COUNTIES ADJACENT TO THE LAKE AND DOWNWIND OF WEST TO NORTHWEST WINDS. THE LONGWAVE TROUGH WILL SHIFT EAST INTO THE CANADIAN MARITIME. AS THE CLOSED LOW OVER IDAHO DEEPENS. A RIDGE WILL BE CLIMBING ASHORE OVER SOUTHWEST CANADA. WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE WILL MOVE INTO EASTERN AND CENTRAL ONTARIO TONIGHT AND SET UP KIND OF A ZONAL FLOW ACROSS THE CENTRAL CONUS. MID LEVEL WINDS WILL BACK A LITTLE MORE WEST OVER THE AREA TONIGHT. THE SURFACE HIGH WILL SHIFT TO EASTERN OHIO RIVER VALLEY. LOW LEVEL CONVERGENCE ALONG THE LAKE SHORE WILL KEEP SOME LAKE EFFECTS SNOWS GOING IN THAT AREA. SPOTTER REPORTS INDICATE THAT THE SNOW IS VERY FINE AND NOT MUCH ACCUMULATION TAKING PLACE OVER NORTHERN ALGER AND LUCE COUNTIES. HOWEVER...WINDS CONTINUE TO BE STRONG THIS AFTERNOON. GUIDANCE SHOW AS THE HIGH MOVES EAST TONIGHT...PRESSURE GRADIENTS OVER THE AREA WILL WEAKEN AND WIND WILL TAPER OFF. THIS SHOULD CAUSE THE BLOWING SNOW TO DIMINISH BY LATE EVENING. RADIATIONAL COOLING WILL CAUSE TEMPERATURES TO DROP TO -20C. WINDS WILL BE TOO LIGHT TO QUALIFY FOR WIND CHILL ADVISORY EXCEPT THIS EVENING. THE LOW OVER THE PACIFIC NORTHWEST WILL SLIDE DOWN THE COAST INTO NORTHERN CALIFORNIA. AN ACCOMPANYING MID LEVEL TROUGH WILL SHIFT INTO THE NORTHERN PLAINS...KEEPING ZONAL FLOW ACROSS THE CONUS. THE LAKE INDUCED SURFACE LOW WILL DEVELOP OVER EASTERN LAKE SUPERIOR ON MONDAY. A SURFACE LOW WILL SLIDE OUT OF THE CENTRAL PLAINS INTO NORTHERN MISSOURI ON MONDAY. WITH THE APPROACH OF THE LOW...GUIDANCE SHOWING A WEAK INSTABILITY AND MOISTURE WORKING NORTH INTO THE SOUTHERN PART OF THE FORECAST AREA. WILL KEEP A SLIGHT CHANCE GOING FOR THE SOUTHERN COUNTIES MONDAY AFTERNOON. 850MB TEMPERATURES WILL KEEP SOME LAKE EFFECT SNOWS GOING INTO THE AFTERNOON. && .LONG TERM (MON NIGHT INTO TUE)... MON NIGHT INTO TUE...SHRTWV MOVING DOWN THROUGH THE NRN MN AND THE DAKOTAS IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING... MAINTAINING THE COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP PROPEL SYSTEM OVER ERN KANSAS NORTHEAST THROUGH LOWER MICHIGAN DURING THIS PERIOD. KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE LAKE MICHIGAN SHORELINE AS GFS STILL INDICATES MID-LVL FRONTOGENETICAL FORCING AND BOTH GFS/UKMET BRING SOME LIGHT PCPN INTO THE ERN CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW. WINDS REMAIN MOSTLY WESTERLY MON NIGHT FAVORING PERHAPS A MAIN CONVERGENT BAND OVER NORTHERN HOUGHTON COUNTY. BY TUE AFTERNOON... WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. THIS SLIGHT VEERING OF WINDS SHOULD BRING LES BACK INTO ONTONAGON COUNTY UP THROUGH THE KEWEENAW SO WILL MAINTAIN LIKELY POPS FOR THESE AREAS. RAISED TEMPS A FEW MORE DEGREES MONDAY NIGHT AS CLOUD COVER FROM SYSTEM MOVING THROUGH LOWER MIDWEST SHOULD KEEP TEMPS UP...ALTHOUGH STILL EXPECT SINGLE DIGITS BLO ZERO OVER THE WRN INTERIOR. TUE HIGH TEMPS SHOULD BE FAIRLY SIMILAR TO MON. TUE NIGHT INTO WED...MODELS SHOW POTENT SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA TUE EVENING INTO THE UPPER GREAT LAKES. GFS/UKMET/ECMWF PROG 850MB TEMPS TO BE -25 TO -28C ACROSS UPPER MI BY WED MORNING IN THE WAKE OF THE SHORTWAVE. THE SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH WILL INTENSIFY THE LOW LEVEL CONVERGENCE OVER THE KEWEENAW PENINSULA AND THE ERN COUNTIES TUE NIGHT INTO WED. LIKELY POPS STILL ON TARGET FOR FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING IN...HIGH TEMPS AGAIN MAY STRUGGLE TO REACH ABV ZERO ON WED. ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA BY THU...WHICH SHOULD HELP MODERATE TEMPS. THIS WARMING IN TANDEM WITH FLOW BACKING MORE WRLY SHOULD HELP TAPER LES TO FLURRIES OVER THE KEWEENAW PENINSULA AND ERN SHORELINE OF THE CWA. EXPECT DRY CONDITIONS THU NIGHT INTO FRI AS BOTH THE OPERATIONAL GFS AND ECMWF INDICATE RIDGING OVER THE AREA. AGREEMENT OF THE OPERATIONAL RUNS WITH THE GFS ENSEMBLE MEAN ALSO INCREASES CONFIDENCE IN KEEPING THIS PERIOD DRY. ARRIVAL OF ANOTHER SHORTWAVE TROF FOR THE FRI NIGHT INTO SAT TIME FRAME PER ECMWF AND GFS WILL WARRANT CHC POPS FOR SNOW ACROSS THE CWA. SHIFT TO NWRLY WINDS SAT NIGHT INTO SUN BEHIND FRONTAL SYSTEM SHOULD KEEP SOME LES AROUND FOR THE NRN AND ERN COUNTIES WHILE ISOLATED SNOW SHOWERS OR FLURRIES CAN BE EXPECTED FURTHER SOUTH. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU THIS EVENING...LITTLE CHANGE IN PREVAILING CONDITIONS WILL OCCUR AT BOTH SITES DURING THE FCST PERIOD. AT KCMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SNOW FLAKES THAT WILL EFFECTIVELY REDUCE VSBY. LOOK FOR VFR CONDITIONS AT KSAW FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM THIS AFTERNOON WITHIN H85 THERMAL TROF AS WAS THE CASE SAT AFTERNOON. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NORTHWEST WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE LOWER GREAT LAKES AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN...LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003. WIND CHILL ADVISORY UNTIL 11 AM EST /10 AM CST/ MONDAY FOR MIZ002-004-005-009>011-084. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ006- 007. LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY FOR LSZ263>267. LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250. && $$ SHORT TERM...DLG LONG TERM...VOSS AVIATION...DLG MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 134 PM EST SUN JAN 20 2008 .SHORT TERM... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE SNOW AND WIND CHILL READINGS THIS AFTERNOON. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA AND NEW ENGLAND. A CLOSED LOW IS DEVELOPING OVER THE PACIFIC NORTHWEST AND LARGE RIDGE RUNS THE WEST COAST. WEAK SHORTWAVE SAILING DOWN THE LEE OF THE RIDGE ARE SWEEPING THE MANITOBA AND EASTERN U.P. SURFACE ANALYSIS PORTRAYS A LARGE HIGH OVER THE MIDDLE MISSISSIPPI RIVER VALLEY WITH A RIDGE REACHING NORTHWEST INTO ALBERTA. A WEAK COLD FRONT OR TROUGH CONTINUES TO STRETCH ACROSS LAKE SUPERIOR. ANTI-CYCLONIC FLOW EAST OF THE RIDGE IS PULLING THE COLD AIR OUT OF CENTRAL CANADA INTO THE FORECAST AREA. LOW LEVEL CONVERGENCE WITH THE FRONTAL SYSTEM...THE COLD AIR...AND LOW LEVEL MOISTURE BELOW 850MB CONTRIBUTE TO LAKE EFFECT SNOWS OCCURRING OVER THE AREA AND LOW WIND CHILLS. THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN NORTH AMERICA THIS AFTERNOON. THE CLOSED LOW WILL EDGE INTO WEST CENTRAL IDAHO. THE MISSISSIPPI RIVER VALLEY HIGH WILL START TO SLIP INTO WESTERN OHIO RIVER VALLEY KEEPING THE RIDGE OVER MINNESOTA...EASTERN NORTH DAKOTA AND SOUTHERN SASKATCHEWAN. THUS ONLY MINOR CHANGES IN THE SYNOPIC PATTERN EXPECTED. 850MB TEMPERATURES AROUND -25C WILL CONTINUE OVER THE AREA. THE BEST SNOW GROWTH AREA CONTINUES TO BE IN THE LOW LEVEL. WINDS ARE GENERALLY IN THE 5 TO 15 MPH RANGE. UNDER MOSTLY CLEAR SKIES...TEMPERATURES ARE COMING UP. MOST ALL THE REPORTING STATION THROUGH UPPER MICHIGAN HAVE MODERATE WIND CHILLS...THUS WILL CANCEL ALL THE WIND CHILL ADVISORIES EXCEPT FOR GOGEBIC COUNTY. .LONG TERM... TONIGHT...UPPER FLOW TURNS MORE WESTERLY AS THE SHRTWV OVER CENTRAL SASKATCHEWAN DROPS DOWN INTO NORTH DAKOTA. AT THE SURFACE...THIS ALLOWS FOR THE HIGH PRESSURE RIDGE THAT HAS BEEN OVER THE DAKOTAS INTO MN TO START BUILDING INTO THE CWA. THUS...LOW LEVEL WIND FLOW SHOULD BACK TOWARDS THE SOUTHWEST...ENHANCED BY LAND BREEZES. WITH THE ADJUSTMENT TO THE WIND FIELD...CONVERGENCE AREAS SHIFT NORTH...MORE OVER THE KEWEENAW AND TOWARDS WAWA ONTARIO. THEREFORE...LAKE EFFECT SNOWS THAT HAVE BEEN STUCK OVER THE EASTERN CWA WILL MOSTLY END TOWARDS SUNRISE. HAVE DECLINED TO EXTEND THE WARNINGS FOR THE EAST PAST 00Z AS IT LOOKS MORE LIKE AN ADVISORY SCENARIO FOR TONIGHT. DID EXTEND ADVISORIES FOR THE WESTERN CWA THROUGH TONIGHT...THOUGH...GIVEN THE BREEZY CONDITIONS AND PERSISTENT FINE SNOWFLAKES. WITH THE SURFACE FLOW BACKING TO THE SOUTHWEST AND DIMINISHING WIND SPEEDS INLAND...READINGS MAY GET QUITE COLD. COOP GUIDANCE OF -20F FOR CHAMPION SEEMS LIKELY... ESPECIALLY GIVEN READINGS UPSTREAM IN MN. INCOMING HIGH CLOUDS LATE THROUGH THE UPPER FLOW MAY HELP KEEP TEMPS FROM DROPPING TOO MUCH LOWER. AS FAR AS WIND CHILLS...COLDEST AREAS WILL NOT MEET THE WIND CRITERIA (LIKELY CALM WINDS AT THE COLDEST AREAS)...THUS AM HESITANT AT THIS POINT TO EXTEND GOING WIND CHILL ADVISORIES. MONDAY...SHRTWV DROPPING THROUGH NORTH DAKOTA TONIGHT MOVES INTO THE GRAND FORKS AREA BY 00Z. MEANWHILE...A SHRTWV CURRENTLY LOCATED ON THE WEST SIDE OF THE PACIFIC NW UPPER TROUGH IS SHOWN TO MOVE EASTWARD ACROSS THE ROCKIES INTO KANSAS BY 00Z. IN RESPONSE TO THIS SECOND SHRTWV...LOW PRESSURE DEVELOPS NEAR KANSAS CITY. MID-LEVEL FRONTOGENESIS/ISENTROPIC LIFT NORTH AND NORTHEAST OF THIS LOW COMBINED WITH A GULF OF MEXICO MOISTURE CONNECTION SHOULD SPREAD LIGHT SNOW INTO WISCONSIN THROUGH THE DAY. IT IS POSSIBLE THAT SOME OF THE SNOW COULD ALSO SPREAD INTO THE SOUTHERN U.P....WITH THE DRY AIRMASS IN PLACE THE MAIN PROBLEM OF SPREADING THE SNOW NORTHWARD. THE ONLY OTHER ITEM OF CONCERN IS THE LAKE EFFECT SNOW ACROSS THE KEWEENAW PENINSULA. THE NAM/GFS/LOCAL WRF-ARW DEPICT A DECENT LOW LEVEL CONVERGENCE ZONE SETTING UP THERE...IN ADDITION TO A WARMER SOUNDING PROFILE FAVORING MORE DENDRITE PRODUCTION. THUS...SNOW TO WATER RATIOS SHOULD GO UP. SINCE PLENTY OF WIND STILL REMAINS IN THE BOUNDARY LAYER...AND FORECAST SNOWFALL AMOUNTS OF 3-5 INCHES...HAVE DECIDED TO EXTEND THE ADVISORY FOR THE KEWEENAW PENINSULA TO 00Z TUE. AS MENTIONED EARLIER...WARMER AIR MOVES INTO THE CWA...WHICH SHOULD BRING TEMPS UP 5 TO 8 DEGREES MORE THAN THOSE TODAY. STILL...THE VALUES REMAIN 10 TO 15 DEGREES BELOW NORMAL. MON NIGHT INTO TUE...SHRTWV OVER NW MN IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING...MAINTAINING COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP KEEP THE SYSTEM OVER KANSAS CITY...WHICH IS SHOWN TO MOVE UP THROUGH LOWER MICHIGAN DURING THIS PERIOD...FAIRLY PROGRESSIVE. HAVE KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE LAKE MICHIGAN SHORELINE FOR ANY FRONTOGENETICAL PCPN THAT MAKES IT INTO THE CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW. WINDS REMAIN MOSTLY WESTERLY MON NIGHT...FAVORING MAINLY THE WESTERN U.P.. HARD TO TELL IF THERE WILL BE ANY MAIN CONVERGENT BAND AT THIS POINT...BUT IF ANYWHERE WOULD PROBABLY BE SITUATED IN NORTHERN HOUGHTON COUNTY. FOR TUE...WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. HOWEVER...IT NEVER LOOKS LIKE THEY WILL FULLY GO NW AS MODELS SHOW ANOTHER SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA...WHICH WOULD HELP TO KEEP THE FLOW BACKED MORE. THUS...THE BEST AREA FOR LAKE EFFECT ON TUE REMAINS FROM ONTONAGON COUNTY THROUGH THE KEWEENAW...AND HAVE RAISED POPS TO LIKELY. RAISED TEMPS A FEW DEGREES MONDAY NIGHT WITH CLOUD COVER FROM THE SYSTEM KEEPING TEMPS UP. TUES TEMPS LOOK FAIRLY SIMILAR TO MON. TUE NIGHT INTO WED...SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA LOOKS FAIRLY POTENT...AND THE GFS/UKMET/ECMWF REFLECT THIS IN 850MB TEMP FIELDS...SHOWING ANOTHER BATCH OF -25 TO -28C AIR DROPPING INTO UPPER MI BY WED MORNING. THE SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH SHOULD INTENSIFY THE LOW LEVEL CONVERGENCE OVER THE KEWEENAW PENINSULA TUE NIGHT...WHICH WILL THEN DROP SOUTH THROUGH THE CWA ON WED. THUS...LIKELY POPS SEEM REASONABLE AT LEAST FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING IN ON WED...COOLED HIGH TEMPS A FEW DEGREES. BEYOND WED...ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA ON THU...WHICH SHOULD HELP MODERATE TEMPS. NO CHANGES MADE TO THE FORECAST AFTER WED. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU THIS EVENING...LITTLE CHANGE IN PREVAILING CONDITIONS WILL OCCUR AT BOTH SITES DURING THE FCST PERIOD. AT KCMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SNOW FLAKES THAT WILL EFFECTIVELY REDUCE VSBY. LOOK FOR VFR CONDITIONS AT KSAW FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM THIS AFTERNOON WITHIN H85 THERMAL TROF AS WAS THE CASE SAT AFTERNOON. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NW WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TODAY AND TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE CENTRAL GREAT LAKES AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... WIND CHILL ADVISORY UNTIL NOON CST/ THIS AFTERNOON FOR MIZ002. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING MIZ006-007. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250. && $$ SHORT TERM...DLG LONG TERM...AJ AVIATION...DLG MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 650 AM EST SUN JAN 20 2008 UPDATED FOR 12Z TAF DISCUSSION .SYNOPSIS... 09Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING ACROSS MUCH OF NORTH AMERICA...WHICH IS ACTUALLY MADE UP OF TWO SEPARATES TROUGH. ONE TROUGH CAN BE SEEN DROPPING SOUTH THROUGH BRITISH COLUMBIA AND THE PACIFIC NW...WHILE THE MAIN LONGWAVE TROUGH STRETCHES FROM HUDSON BAY SOUTHWARD THROUGH THE GREAT LAKES AND INTO THE OHIO VALLEY. WITHIN THE MAIN LONGWAVE TROUGH...SHRTWVS TO NOTE ARE OVER WESTERN LAKE SUPERIOR AND CENTRAL SASKATCHEWAN. SHRTWV OVER WESTERN LAKE SUPERIOR DOES HAVE SOME MOISTURE WITH IT...AS NOTED BY NEARLY SATURATED CONDITIONS BETWEEN 900-600MB ON THE 00Z CWPL SOUNDING. HOWEVER...GIVEN THAT THE ENTIRE SOUNDING IS BELOW -25C...THE PRECIPITABLE WATER IS QUITE LOW AT 0.05 INCH. WOULD ASSUME THAT THIS MOISTURE IS PROVIDING SOME LAKE ENHANCEMENT TO THE ONGOING LAKE EFFECT...BUT GIVEN HOW COLD THE AIRMASS IS...SNOWFLAKE SIZE IS STILL PROBABLY SMALL...ESPECIALLY OVER THE WESTERN U.P. WITH THE SHORTER FETCH NOT ALLOWING FOR AS MUCH WARMING. THE AIR THAT IS COMING IN ON THE WEST SIDE OF THE SHRTWV IS REPRESENTED BY THE 00Z INL SOUNDING...WHICH IS ALSO ALL BELOW -25C BUT WITH DEWPOINT DEPRESSIONS OF 5-10C FROM THE SFC TO 300MB. THIS DRIER AIR COMBINED WITH CLEAR SKIES...ALONG WITH A RIDGE OF HIGH PRESSURE AT THE SURFACE...HAS ALLOWED TEMPS TO FALL OVER MN INTO THE -20S F. THANKS TO SOME FLOW OFF LAKE SUPERIOR...TEMPS ARE ONLY IN THE SINGLE DIGITS TO TEENS BELOW ZERO...EXCLUDING THOSE IMMEDIATELY NEAR THE SHORE THAT HAVE NW WINDS. NEXT NEAREST SYNOPTIC CLOUDS ARE OVER SOUTH DAKOTA ASSOCIATED WITH THE TROUGH DROPPING THROUGH THE PACIFIC NW. && .DISCUSSION... MAIN FORECAST CONCERN IS MOSTLY LAKE EFFECT SNOW THROUGH WEDNESDAY. TODAY...BASICALLY A REPEAT OF YESTERDAY...WITH ARCTIC AIR REMAINING IN PLACE WITH NW UPPER FLOW ALOFT. THIS UPPER FLOW DOES BACK A BIT MORE WESTERLY BY THE END OF THE DAY...SO SOME SLIGHT 850MB WARMING IS SHOWN TO OCCUR. STILL...READINGS REMAIN AT OR BELOW -23C WITH GENERAL LOW LEVEL WNW FLOW. LOW LEVEL CONVERGENCE AREAS ARE INDICATED TO REMAIN IN PLACE OVER ONTONAGON INTO NORTHERN HOUGHTON COUNTIES...AND OVER EASTERN ALGER INTO NORTHERN LUCE COUNTIES DUE TO LAKE INDUCED TROUGHING. HOWEVER...STRONGEST LOW LEVEL CONVERGENCE IS DEPICTED IN THE EASTERN CWA...AND WITH THE LONGER FETCH OFF LAKE SUPERIOR MAXIMIZING THE MOST WARMING AND THUS BETTER SNOW CRYSTAL TYPE (NOTED BY SOUNDINGS DEPICTING A CHANCE FOR SOME DENDRITES TO FORM)...THIS AREA SHOULD PICK UP THE MOST SNOW OUT OF THE CWA. IN THIS AREA...WOULD EXPECT SNOW TO WATER RATIOS SOMEWHERE NEAR 25 TO 1...COMPARED TO 20 TO 1 OR LESS IN THE WESTERN CWA. GOING WARNINGS FOR THE EASTERN CWA LOOK GOOD. HAVE DECIDED TO EXTEND ADVISORIES OVER THE WESTERN CWA GIVEN BREEZY CONDITIONS EXPECTED THERE ALONG WITH PERSISTENT FINE SNOWFLAKES. OVER THE REST OF THE CWA...ANOTHER DRY COLD DAY WITH SOME DIURNAL STRATOCUMULUS IS EXPECTED. TONIGHT...UPPER FLOW TURNS MORE WESTERLY AS THE SHRTWV OVER CENTRAL SASKATCHEWAN DROPS DOWN INTO NORTH DAKOTA. AT THE SURFACE...THIS ALLOWS FOR THE HIGH PRESSURE RIDGE THAT HAS BEEN OVER THE DAKOTAS INTO MN TO START BUILDING INTO THE CWA. THUS...LOW LEVEL WIND FLOW SHOULD BACK TOWARDS THE SOUTHWEST...ENHANCED BY LAND BREEZES. WITH THE ADJUSTMENT TO THE WIND FIELD...CONVERGENCE AREAS SHIFT NORTH...MORE OVER THE KEWEENAW AND TOWARDS WAWA ONTARIO. THEREFORE...LAKE EFFECT SNOWS THAT HAVE BEEN STUCK OVER THE EASTERN CWA WILL MOSTLY END TOWARDS SUNRISE. HAVE DECLINED TO EXTEND THE WARNINGS FOR THE EAST PAST 00Z AS IT LOOKS MORE LIKE AN ADVISORY SCENARIO FOR TONIGHT. DID EXTEND ADVISORIES FOR THE WESTERN CWA THROUGH TONIGHT...THOUGH...GIVEN THE BREEZY CONDITIONS AND PERSISTENT FINE SNOWFLAKES. WITH THE SURFACE FLOW BACKING TO THE SOUTHWEST AND DIMINISHING WIND SPEEDS INLAND...READINGS MAY GET QUITE COLD. COOP GUIDANCE OF -20F FOR CHAMPION SEEMS LIKELY... ESPECIALLY GIVEN READINGS UPSTREAM IN MN. INCOMING HIGH CLOUDS LATE THROUGH THE UPPER FLOW MAY HELP KEEP TEMPS FROM DROPPING TOO MUCH LOWER. AS FAR AS WIND CHILLS...COLDEST AREAS WILL NOT MEET THE WIND CRITERIA (LIKELY CALM WINDS AT THE COLDEST AREAS)...THUS AM HESITANT AT THIS POINT TO EXTEND GOING WIND CHILL ADVISORIES. MONDAY...SHRTWV DROPPING THROUGH NORTH DAKOTA TONIGHT MOVES INTO THE GRAND FORKS AREA BY 00Z. MEANWHILE...A SHRTWV CURRENTLY LOCATED ON THE WEST SIDE OF THE PACIFIC NW UPPER TROUGH IS SHOWN TO MOVE EASTWARD ACROSS THE ROCKIES INTO KANSAS BY 00Z. IN RESPONSE TO THIS SECOND SHRTWV...LOW PRESSURE DEVELOPS NEAR KANSAS CITY. MID-LEVEL FRONTOGENESIS/ISENTROPIC LIFT NORTH AND NORTHEAST OF THIS LOW COMBINED WITH A GULF OF MEXICO MOISTURE CONNECTION SHOULD SPREAD LIGHT SNOW INTO WISCONSIN THROUGH THE DAY. IT IS POSSIBLE THAT SOME OF THE SNOW COULD ALSO SPREAD INTO THE SOUTHERN U.P....WITH THE DRY AIRMASS IN PLACE THE MAIN PROBLEM OF SPREADING THE SNOW NORTHWARD. THE ONLY OTHER ITEM OF CONCERN IS THE LAKE EFFECT SNOW ACROSS THE KEWEENAW PENINSULA. THE NAM/GFS/LOCAL WRF-ARW DEPICT A DECENT LOW LEVEL CONVERGENCE ZONE SETTING UP THERE...IN ADDITION TO A WARMER SOUNDING PROFILE FAVORING MORE DENDRITE PRODUCTION. THUS...SNOW TO WATER RATIOS SHOULD GO UP. SINCE PLENTY OF WIND STILL REMAINS IN THE BOUNDARY LAYER...AND FORECAST SNOWFALL AMOUNTS OF 3-5 INCHES...HAVE DECIDED TO EXTEND THE ADVISORY FOR THE KEWEENAW PENINSULA TO 00Z TUE. AS MENTIONED EARLIER...WARMER AIR MOVES INTO THE CWA...WHICH SHOULD BRING TEMPS UP 5 TO 8 DEGREES MORE THAN THOSE TODAY. STILL...THE VALUES REMAIN 10 TO 15 DEGREES BELOW NORMAL. MON NIGHT INTO TUE...SHRTWV OVER NW MN IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING...MAINTAINING COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP KEEP THE SYSTEM OVER KANSAS CITY...WHICH IS SHOWN TO MOVE UP THROUGH LOWER MICHIGAN DURING THIS PERIOD...FAIRLY PROGRESSIVE. HAVE KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE LAKE MICHIGAN SHORELINE FOR ANY FRONTOGENETICAL PCPN THAT MAKES IT INTO THE CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW. WINDS REMAIN MOSTLY WESTERLY MON NIGHT...FAVORING MAINLY THE WESTERN U.P.. HARD TO TELL IF THERE WILL BE ANY MAIN CONVERGENT BAND AT THIS POINT...BUT IF ANYWHERE WOULD PROBABLY BE SITUATED IN NORTHERN HOUGHTON COUNTY. FOR TUE...WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. HOWEVER...IT NEVER LOOKS LIKE THEY WILL FULLY GO NW AS MODELS SHOW ANOTHER SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA...WHICH WOULD HELP TO KEEP THE FLOW BACKED MORE. THUS...THE BEST AREA FOR LAKE EFFECT ON TUE REMAINS FROM ONTONAGON COUNTY THROUGH THE KEWEENAW...AND HAVE RAISED POPS TO LIKELY. RAISED TEMPS A FEW DEGREES MONDAY NIGHT WITH CLOUD COVER FROM THE SYSTEM KEEPING TEMPS UP. TUES TEMPS LOOK FAIRLY SIMILAR TO MON. TUE NIGHT INTO WED...SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA LOOKS FAIRLY POTENT...AND THE GFS/UKMET/ECMWF REFLECT THIS IN 850MB TEMP FIELDS...SHOWING ANOTHER BATCH OF -25 TO -28C AIR DROPPING INTO UPPER MI BY WED MORNING. THE SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH SHOULD INTENSIFY THE LOW LEVEL CONVERGENCE OVER THE KEWEENAW PENINSULA TUE NIGHT...WHICH WILL THEN DROP SOUTH THROUGH THE CWA ON WED. THUS...LIKELY POPS SEEM REASONABLE AT LEAST FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING IN ON WED...COOLED HIGH TEMPS A FEW DEGREES. BEYOND WED...ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA ON THU...WHICH SHOULD HELP MODERATE TEMPS. NO CHANGES MADE TO THE FORECAST AFTER WED. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU THIS EVENING... EXPECT LITTLE CHANGE IN PREVAILING CONDITIONS AT BOTH SITES DURING THE FCST PERIOD. AT KCMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SNOW FLAKES THAT WILL EFFECTIVELY REDUCE VSBY. LOOK FOR VFR CONDITIONS AT KSAW FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM THIS AFTERNOON WITHIN H85 THERMAL TROF AS WAS THE CASE SAT AFTERNOON. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NW WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TODAY AND TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE CENTRAL GREAT LAKES AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR MIZ002-004-005-009>014-084. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING MIZ006-007. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION/MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 419 AM EST SUN JAN 20 2008 .SYNOPSIS... 09Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING ACROSS MUCH OF NORTH AMERICA...WHICH IS ACTUALLY MADE UP OF TWO SEPARATES TROUGH. ONE TROUGH CAN BE SEEN DROPPING SOUTH THROUGH BRITISH COLUMBIA AND THE PACIFIC NW...WHILE THE MAIN LONGWAVE TROUGH STRETCHES FROM HUDSON BAY SOUTHWARD THROUGH THE GREAT LAKES AND INTO THE OHIO VALLEY. WITHIN THE MAIN LONGWAVE TROUGH...SHRTWVS TO NOTE ARE OVER WESTERN LAKE SUPERIOR AND CENTRAL SASKATCHEWAN. SHRTWV OVER WESTERN LAKE SUPERIOR DOES HAVE SOME MOISTURE WITH IT...AS NOTED BY NEARLY SATURATED CONDITIONS BETWEEN 900-600MB ON THE 00Z CWPL SOUNDING. HOWEVER...GIVEN THAT THE ENTIRE SOUNDING IS BELOW -25C...THE PRECIPITABLE WATER IS QUITE LOW AT 0.05 INCH. WOULD ASSUME THAT THIS MOISTURE IS PROVIDING SOME LAKE ENHANCEMENT TO THE ONGOING LAKE EFFECT...BUT GIVEN HOW COLD THE AIRMASS IS...SNOWFLAKE SIZE IS STILL PROBABLY SMALL...ESPECIALLY OVER THE WESTERN U.P. WITH THE SHORTER FETCH NOT ALLOWING FOR AS MUCH WARMING. THE AIR THAT IS COMING IN ON THE WEST SIDE OF THE SHRTWV IS REPRESENTED BY THE 00Z INL SOUNDING...WHICH IS ALSO ALL BELOW -25C BUT WITH DEWPOINT DEPRESSIONS OF 5-10C FROM THE SFC TO 300MB. THIS DRIER AIR COMBINED WITH CLEAR SKIES...ALONG WITH A RIDGE OF HIGH PRESSURE AT THE SURFACE...HAS ALLOWED TEMPS TO FALL OVER MN INTO THE -20S F. THANKS TO SOME FLOW OFF LAKE SUPERIOR...TEMPS ARE ONLY IN THE SINGLE DIGITS TO TEENS BELOW ZERO...EXCLUDING THOSE IMMEDIATELY NEAR THE SHORE THAT HAVE NW WINDS. NEXT NEAREST SYNOPTIC CLOUDS ARE OVER SOUTH DAKOTA ASSOCIATED WITH THE TROUGH DROPPING THROUGH THE PACIFIC NW. && .DISCUSSION... MAIN FORECAST CONCERN IS MOSTLY LAKE EFFECT SNOW THROUGH WEDNESDAY. TODAY...BASICALLY A REPEAT OF YESTERDAY...WITH ARCTIC AIR REMAINING IN PLACE WITH NW UPPER FLOW ALOFT. THIS UPPER FLOW DOES BACK A BIT MORE WESTERLY BY THE END OF THE DAY...SO SOME SLIGHT 850MB WARMING IS SHOWN TO OCCUR. STILL...READINGS REMAIN AT OR BELOW -23C WITH GENERAL LOW LEVEL WNW FLOW. LOW LEVEL CONVERGENCE AREAS ARE INDICATED TO REMAIN IN PLACE OVER ONTONAGON INTO NORTHERN HOUGHTON COUNTIES...AND OVER EASTERN ALGER INTO NORTHERN LUCE COUNTIES DUE TO LAKE INDUCED TROUGHING. HOWEVER...STRONGEST LOW LEVEL CONVERGENCE IS DEPICTED IN THE EASTERN CWA...AND WITH THE LONGER FETCH OFF LAKE SUPERIOR MAXIMIZING THE MOST WARMING AND THUS BETTER SNOW CRYSTAL TYPE (NOTED BY SOUNDINGS DEPICTING A CHANCE FOR SOME DENDRITES TO FORM)...THIS AREA SHOULD PICK UP THE MOST SNOW OUT OF THE CWA. IN THIS AREA...WOULD EXPECT SNOW TO WATER RATIOS SOMEWHERE NEAR 25 TO 1...COMPARED TO 20 TO 1 OR LESS IN THE WESTERN CWA. GOING WARNINGS FOR THE EASTERN CWA LOOK GOOD. HAVE DECIDED TO EXTEND ADVISORIES OVER THE WESTERN CWA GIVEN BREEZY CONDITIONS EXPECTED THERE ALONG WITH PERSISTENT FINE SNOWFLAKES. OVER THE REST OF THE CWA...ANOTHER DRY COLD DAY WITH SOME DIURNAL STRATOCUMULUS IS EXPECTED. TONIGHT...UPPER FLOW TURNS MORE WESTERLY AS THE SHRTWV OVER CENTRAL SASKATCHEWAN DROPS DOWN INTO NORTH DAKOTA. AT THE SURFACE...THIS ALLOWS FOR THE HIGH PRESSURE RIDGE THAT HAS BEEN OVER THE DAKOTAS INTO MN TO START BUILDING INTO THE CWA. THUS...LOW LEVEL WIND FLOW SHOULD BACK TOWARDS THE SOUTHWEST...ENHANCED BY LAND BREEZES. WITH THE ADJUSTMENT TO THE WIND FIELD...CONVERGENCE AREAS SHIFT NORTH...MORE OVER THE KEWEENAW AND TOWARDS WAWA ONTARIO. THEREFORE...LAKE EFFECT SNOWS THAT HAVE BEEN STUCK OVER THE EASTERN CWA WILL MOSTLY END TOWARDS SUNRISE. HAVE DECLINED TO EXTEND THE WARNINGS FOR THE EAST PAST 00Z AS IT LOOKS MORE LIKE AN ADVISORY SCENARIO FOR TONIGHT. DID EXTEND ADVISORIES FOR THE WESTERN CWA THROUGH TONIGHT...THOUGH...GIVEN THE BREEZY CONDITIONS AND PERSISTENT FINE SNOWFLAKES. WITH THE SURFACE FLOW BACKING TO THE SOUTHWEST AND DIMINISHING WIND SPEEDS INLAND...READINGS MAY GET QUITE COLD. COOP GUIDANCE OF -20F FOR CHAMPION SEEMS LIKELY... ESPECIALLY GIVEN READINGS UPSTREAM IN MN. INCOMING HIGH CLOUDS LATE THROUGH THE UPPER FLOW MAY HELP KEEP TEMPS FROM DROPPING TOO MUCH LOWER. AS FAR AS WIND CHILLS...COLDEST AREAS WILL NOT MEET THE WIND CRITERIA (LIKELY CALM WINDS AT THE COLDEST AREAS)...THUS AM HESITANT AT THIS POINT TO EXTEND GOING WIND CHILL ADVISORIES. MONDAY...SHRTWV DROPPING THROUGH NORTH DAKOTA TONIGHT MOVES INTO THE GRAND FORKS AREA BY 00Z. MEANWHILE...A SHRTWV CURRENTLY LOCATED ON THE WEST SIDE OF THE PACIFIC NW UPPER TROUGH IS SHOWN TO MOVE EASTWARD ACROSS THE ROCKIES INTO KANSAS BY 00Z. IN RESPONSE TO THIS SECOND SHRTWV...LOW PRESSURE DEVELOPS NEAR KANSAS CITY. MID-LEVEL FRONTOGENESIS/ISENTROPIC LIFT NORTH AND NORTHEAST OF THIS LOW COMBINED WITH A GULF OF MEXICO MOISTURE CONNECTION SHOULD SPREAD LIGHT SNOW INTO WISCONSIN THROUGH THE DAY. IT IS POSSIBLE THAT SOME OF THE SNOW COULD ALSO SPREAD INTO THE SOUTHERN U.P....WITH THE DRY AIRMASS IN PLACE THE MAIN PROBLEM OF SPREADING THE SNOW NORTHWARD. THE ONLY OTHER ITEM OF CONCERN IS THE LAKE EFFECT SNOW ACROSS THE KEWEENAW PENINSULA. THE NAM/GFS/LOCAL WRF-ARW DEPICT A DECENT LOW LEVEL CONVERGENCE ZONE SETTING UP THERE...IN ADDITION TO A WARMER SOUNDING PROFILE FAVORING MORE DENDRITE PRODUCTION. THUS...SNOW TO WATER RATIOS SHOULD GO UP. SINCE PLENTY OF WIND STILL REMAINS IN THE BOUNDARY LAYER...AND FORECAST SNOWFALL AMOUNTS OF 3-5 INCHES...HAVE DECIDED TO EXTEND THE ADVISORY FOR THE KEWEENAW PENINSULA TO 00Z TUE. AS MENTIONED EARLIER...WARMER AIR MOVES INTO THE CWA...WHICH SHOULD BRING TEMPS UP 5 TO 8 DEGREES MORE THAN THOSE TODAY. STILL...THE VALUES REMAIN 10 TO 15 DEGREES BELOW NORMAL. MON NIGHT INTO TUE...SHRTWV OVER NW MN IS PROGGED TO MOVE THROUGH UPPER MI TUE MORNING...MAINTAINING COLD AIR OVER THE CWA. THIS SHRTWV WILL ALSO HELP KEEP THE SYSTEM OVER KANSAS CITY...WHICH IS SHOWN TO MOVE UP THROUGH LOWER MICHIGAN DURING THIS PERIOD...FAIRLY PROGRESSIVE. HAVE KEPT CHANCE POPS GOING FOR MONDAY NIGHT ALONG THE LAKE MICHIGAN SHORELINE FOR ANY FRONTOGENETICAL PCPN THAT MAKES IT INTO THE CWA. OTHERWISE...THE MAIN CONCERN IS LAKE EFFECT SNOW. WINDS REMAIN MOSTLY WESTERLY MON NIGHT...FAVORING MAINLY THE WESTERN U.P.. HARD TO TELL IF THERE WILL BE ANY MAIN CONVERGENT BAND AT THIS POINT...BUT IF ANYWHERE WOULD PROBABLY BE SITUATED IN NORTHERN HOUGHTON COUNTY. FOR TUE...WINDS TURN SLIGHTLY MORE TO THE NW IN THE WAKE OF THE SYSTEM MOVING THROUGH LOWER MICHIGAN. HOWEVER...IT NEVER LOOKS LIKE THEY WILL FULLY GO NW AS MODELS SHOW ANOTHER SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA...WHICH WOULD HELP TO KEEP THE FLOW BACKED MORE. THUS...THE BEST AREA FOR LAKE EFFECT ON TUE REMAINS FROM ONTONAGON COUNTY THROUGH THE KEWEENAW...AND HAVE RAISED POPS TO LIKELY. RAISED TEMPS A FEW DEGREES MONDAY NIGHT WITH CLOUD COVER FROM THE SYSTEM KEEPING TEMPS UP. TUES TEMPS LOOK FAIRLY SIMILAR TO MON. TUE NIGHT INTO WED...SHRTWV TROUGH DROPPING SOUTH THROUGH SOUTH CENTRAL CANADA LOOKS FAIRLY POTENT...AND THE GFS/UKMET/ECMWF REFLECT THIS IN 850MB TEMP FIELDS...SHOWING ANOTHER BATCH OF -25 TO -28C AIR DROPPING INTO UPPER MI BY WED MORNING. THE SURFACE COLD FRONT ASSOCIATED WITH THE TROUGH SHOULD INTENSIFY THE LOW LEVEL CONVERGENCE OVER THE KEWEENAW PENINSULA TUE NIGHT...WHICH WILL THEN DROP SOUTH THROUGH THE CWA ON WED. THUS...LIKELY POPS SEEM REASONABLE AT LEAST FOR THE NW SNOWBELTS. WITH THE COLD AIR MOVING IN ON WED...COOLED HIGH TEMPS A FEW DEGREES. BEYOND WED...ECMWF/GFS SHOW STRONG WARM ADVECTION ACROSS THE CWA ON THU...WHICH SHOULD HELP MODERATE TEMPS. NO CHANGES MADE TO THE FORECAST AFTER WED. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU SUN EVNG... EXPECT LTL CHG IN PREVAILING CONDITIONS AT BOTH SITES THIS FCST PD. AT CMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SN FLAKES THAT WL EFFECTIVELY REDUCE VSBY. LOOK FOR CONDITIONS AT SAW TO BE VFR FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM SUN AFTN WITHIN H85 THERMAL TROF AS WAS THE CASE ON SAT AFTN. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... NW WINDS WILL REMAIN IN THE 15 TO 30 KNOT RANGE TODAY AND TONIGHT AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. 15 TO 25 KNOT WESTERLY WINDS ARE EXPECTED MONDAY INTO EARLY TUESDAY AS A WEAK LOW MOVES THROUGH THE CENTRAL GREAT LAKES AND A LOW PRESSURE TROUGH DEVELOPS OVER NORTHERN ONTARIO. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY AND INCREASING TO 15 TO 30 KNOTS BY WED. HEAVY FREEZING SPRAY WILL CONTINUE INTO MONDAY DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... WIND CHILL ADVISORY UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR MIZ002-004-005-009>014-084. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING MIZ006-007. LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ085. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 PM EST MONDAY FOR MIZ001-003. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST MONDAY FOR MIZ002. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ248-250. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION/MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 830 PM EST SAT JAN 19 2008 .UPDATE... SINCE WRNGS FOR ALGER/LUCE COUNTIES HAVE NOW VERIFIED...UPDATED TO EXTEND GOING LES WRNG FOR THOSE ZNS THRU THE DAY ON SUN. OTHER SGNFT CHG TO FCST WAS TO MODIFY TIMING FOR LES ADVY IN NRN SCHOOLCRAFT COUNTY. LES BANDS HAVE BEEN N OF THE COUNTY FOR QUITE SOME TIME...SO COULD NOT RATIONALIZE CONTINUED ADVY THERE. HOWEVER...SHRTWV DIVING SEWD THRU NW ONTARIO TOWARD NW LK SUP AS SHOWN ON WV IMAGERY IS BEGINNING TO CAUSE WINDS OVER LK SUP TO VEER MORE NW. SO EXPECT BANDS/SHARPER LLVL CNVGC NOW IMPACTING ERN ALGER/NRN LUCE COUNTIES TO SPREAD INLAND OVERNGT INTO AT LEAST INTO AREAS N OF M-28 AS HINTED AT BY LATEST NAM/GFS/RUC13 MODELS. SO...STARTED LES ADVY AT 06Z AND RAN HEADLINE FOR NRN SCHOOLCRAFT THRU THE DAY ON SUN WITH LES EXPECTED TO PERSIST IN COLD WNW FLOW OVER ERN ALGER/LUCE/NRN SCHOOLCRAFT ZNS. OTRW...OTHER GOING HEADLINES FOR LES/WIND CHILLS SEEM ON TRACK. && .SYNOPSIS/SHORT TERM (TONIGHT AND SUNDAY)... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR LAKE EFFECT SNOWS AND WIND CHILLS TONIGHT AND SUNDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN U.P. A RIDGE IS OVER THE PACIFIC NORTHWEST...WITH A WEAK RIDGE EXTENDING FROM WESTERN MONTANA NORTHWARD INTO ALBERTA. A WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE IS OVER THE WESTERN U.P. SURFACE ANALYSIS DEPICTS A 1032MB HIGH IN THE KANSAS CITY AREA WITH A RIDGE EXTENDING NORTHWEST INTO NORTHERN SASKATCHEWAN. A WEAK FRONTAL SYSTEM IS WASHING OUT OVER EASTERN LAKE SUPERIOR. A THERMAL TROUGH IS PRODUCING LAKE-850MB DELTA-T OVER LAKE SUPERIOR OF 29C. THE FRONT IS PRODUCING LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR. TOGETHER WITH THE SHORTWAVE ENERGY ARE GENERATING LAKE EFFECT SNOWS. THE ANTICYCLONIC AHEAD OF THE RIDGE IS CAUSING STRONG WEST AND NORTHWEST FLOW ACROSS THE AREA. THUS AREAS DOWNWIND OF LAKE SUPERIOR CONTINUE TO PRODUCE LAKE EFFECT SNOWS. SIGNIFICANT ACCUMULATION OF LES WILL CONTINUE THROUGH TONIGHT AS MORE WEAK SHORTWAVE SWEEP THROUGH THE AREA TONIGHT...AND THE DELTA-T REMAIN MORE THAN 29C. LOW LEVEL CONVERGENCE IS EXPECTED TO CONTINUE OVER LAKE SUPERIOR. THUS LITTLE CHANGE IN THE WEATHER CAN BE EXPECTED TONIGHT. THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON SUNDAY. THE TROUGH THAT WAS OVER THE U.P. TODAY WILL ROTATE RAPIDLY INTO NEW ENGLAND AS WEAKER SHORTWAVE SWEEP THROUGH THE AREA. ANOTHER TROUGH WILL DEVELOP IN THE LEE OF THE PACIFIC RIDGE AND SLIDE INTO SOUTH CENTRAL CANADA. THE SURFACE HIGH OVER KANSAS CITY WILL MOVE EAST INTO THE WESTERN KENTUCKY AND THE SOUTHERN OHIO RIVER VALLEY. THE WEAK COLD FRONT WILL STILL STRETCH ACROSS EASTERN LAKE SUPERIOR. HEAVY LES CAN BE EXPECTED ALONG THE LAKE SUPERIOR SHORE WHICH IS WHAT IS IN THERE ALREADY. && .LONG TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)... MODELS INDICATE THAT ARCTIC AIRMASS COULD PERSIST INTO AT LEAST MIDWEEK AS BITTER COLD TEMPS AND WIND CHILLS REMAIN A CONCERN INTO THE EARLY PART OF NEXT WEEK. HEADLINES FOR WIND CHILLS WILL LIKELY NEED TO BE EXTENDED SUNDAY NIGHT INTO MON AND MAYBE EVEN INTO TUE AS VERY COLD PATTERN PERSISTS. AMPLIFIED UPR RIDGE OVER WESTERN CANADA IS ALLOWING POLAR AIR A CLEAR PATH TO DESCEND INTO THE UPR GREAT LAKES IN A NRLY FLOW. EXPECT DOUBLE DIGITS BLO ZERO TO REMAIN THE RULE OVER THE INTERIOR OF WEST AND CENTRAL COUNTIES UNDER GENERALLY CLEAR SKIES AND WRLY FLOW OVER THE NEXT FEW NIGHT WHILE HIGH TEMPS STRUGGLE TO REACH NEAR ZERO. WRLY FLOW WILL CONTINUE SOME LES OVER THE KEWEENAW PENINSULA AND ERN COUNTY SHORELINES SUN NIGHT ALTHOUGH FLOW BACKING MORE WSW SHOULD PUSH LES BANDS BACK OFF THE ERN COUNTY SHORELINES BY MON. POOR SNOW GROWTH SHOULD LIMIT ACCUMULATIONS TO 1 TO LOCALLY 4 INCHES SUN NIGHT INTO MON SO DO NOT ANTICIPATE HEADLINES FOR SNOW OR BLOWING SNOW. BY TUE...GFS...UKMET AND ECMWF ALL ADVERTISE ANOTHER SHORTWAVE DESCENDING DOWN ACROSS UPR MI REINFORCING THE ARCTIC AIR OVER THE REGION WITH 850 MB TEMPS DROPPING TO AROUND -25C OR COLDER BY LATE TUE INTO WED. TROFFING OVER LAKE SUPERIOR IS ENHANCED BY THIS SHORTWAVE AND COLDER AIR WHICH WILL IN TURN ENHANCE LOW-LVL CONVERGENCE OVER THE KEWEENAW PENINSULA AND ERN SHORELINE AREAS. LOOK FOR LES TO PICK UP OVER THESE AREAS FOR LATE TUE INTO WED. MODELS THEN POINT TO A TRANSITION IN THE PATTERN FOR LATE NEXT WEEK. OPERATIONAL 00Z ECMWF RUN WAS GENERALLY FAVORED BY NCEP AND FOLLOWED IT FOR DETAILS. TROF BEGINS TO TAKE SHAPE OVER THE WRN CONUS BY THE END OF THE WEEK AS RIDGING BEGINS TO MOVE INTO THE NRN PLAINS. MODERATING TEMPS OVER THE NRN PLAINS WILL GRADUALLY WORK INTO THE UPR GREAT LAKES BY THE END OF THE WEEK AS 850 MB TEMPS REBOUNDING TO AROUND -12C OR SO SHOULD HELP SHAKE BITTER COLD TEMPS FROM THE REGION. ARRIVAL OF SHORTWAVE AND ASSOC SFC LOW PRES SYSTEM FOR FRI INTO SAT WILL WARRANT LOW CHC POPS ACROSS THE AREA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU SUN...EXPECT LTL CHG IN PREVAILING CONDITIONS AT BOTH SITES THIS FCST PD. AT CMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SN FLAKES THAT WL EFFECTIVELY REDUCE VSBY. LOOK FOR CONDITIONS AT SAW TO BE VFR FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM SUN AFTN WITHIN H85 THERMAL TROF AS WAS THE CASE ON SAT AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...THE FRONT OVER EASTERN LAKE SUPERIOR WILL REMAIN STATIONARY THROUGH MONDAY WHILE WEAKENING. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. ANOTHER LOW WILL LIFT OUT OF THE MIDDLE MISSISSIPPI RIVER VALLY THROUGH NORTHERN LOWER MICHIGAN LATE ON MONDAY AND TO SOUTHERN QUEBEC ON TUESDAY. ANOTHER HIGH PRESSURE SYSTEM DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY WILL MOVE INTO THE OHIO RIVER VALLEY AS A LOW DEVELOPS OVER THE LAKE SUPERIOR. COLD TEMPERATURES AND STRONG WINDS WILL PRODUCE CONSIDERABLE HEAVY FREEZING SPRAY THROUGH MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN...WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002- 004-005-009>014-084. LAKE EFFECT SNOW ADVISORY FROM 1 AM TO 7 PM EST SUNDAY FOR MIZ085. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ001>003. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SUNDAY FOR MIZ006-007. LAKE SUPERIOR...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LSZ263>267. LAKE MICHIGAN...HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST MONDAY FOR LMZ221-248-250. && $$ UPDATE...KC SHORT TERM...DLG LONG TERM...VOSS AVIATION...KC MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 630 PM EST SAT JAN 19 2008 UPDATED FOR 00Z TAFS .SYNOPSIS/SHORT TERM (TONIGHT AND SUNDAY)... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR LAKE EFFECT SNOWS AND WIND CHILLS TONIGHT AND SUNDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN U.P. A RIDGE IS OVER THE PACIFIC NORTHWEST...WITH A WEAK RIDGE EXTENDING FROM WESTERN MONTANA NORTHWARD INTO ALBERTA. A WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE IS OVER THE WESTERN U.P. SURFACE ANALYSIS DEPICTS A 1032MB HIGH IN THE KANSAS CITY AREA WITH A RIDGE EXTENDING NORTHWEST INTO NORTHERN SASKATCHEWAN. A WEAK FRONTAL SYSTEM IS WASHING OUT OVER EASTERN LAKE SUPERIOR. A THERMAL TROUGH IS PRODUCING LAKE-850MB DELTA-T OVER LAKE SUPERIOR OF 29C. THE FRONT IS PRODUCING LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR. TOGETHER WITH THE SHORTWAVE ENERGY ARE GENERATING LAKE EFFECT SNOWS. THE ANTICYCLONIC AHEAD OF THE RIDGE IS CAUSING STRONG WEST AND NORTHWEST FLOW ACROSS THE AREA. THUS AREAS DOWNWIND OF LAKE SUPERIOR CONTINUE TO PRODUCE LAKE EFFECT SNOWS. SIGNIFICANT ACCUMULATION OF LES WILL CONTINUE THROUGH TONIGHT AS MORE WEAK SHORTWAVE SWEEP THROUGH THE AREA TONIGHT...AND THE DELTA-T REMAIN MORE THAN 29C. LOW LEVEL CONVERGENCE IS EXPECTED TO CONTINUE OVER LAKE SUPERIOR. THUS LITTLE CHANGE IN THE WEATHER CAN BE EXPECTED TONIGHT. THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON SUNDAY. THE TROUGH THAT WAS OVER THE U.P. TODAY WILL ROTATE RAPIDLY INTO NEW ENGLAND AS WEAKER SHORTWAVE SWEEP THROUGH THE AREA. ANOTHER TROUGH WILL DEVELOP IN THE LEE OF THE PACIFIC RIDGE AND SLIDE INTO SOUTH CENTRAL CANADA. THE SURFACE HIGH OVER KANSAS CITY WILL MOVE EAST INTO THE WESTERN KENTUCKY AND THE SOUTHERN OHIO RIVER VALLEY. THE WEAK COLD FRONT WILL STILL STRETCH ACROSS EASTERN LAKE SUPERIOR. HEAVY LES CAN BE EXPECTED ALONG THE LAKE SUPERIOR SHORE WHICH IS WHAT IS IN THERE ALREADY. && .LONG TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)... MODELS INDICATE THAT ARCTIC AIRMASS COULD PERSIST INTO AT LEAST MIDWEEK AS BITTER COLD TEMPS AND WIND CHILLS REMAIN A CONCERN INTO THE EARLY PART OF NEXT WEEK. HEADLINES FOR WIND CHILLS WILL LIKELY NEED TO BE EXTENDED SUNDAY NIGHT INTO MON AND MAYBE EVEN INTO TUE AS VERY COLD PATTERN PERSISTS. AMPLIFIED UPR RIDGE OVER WESTERN CANADA IS ALLOWING POLAR AIR A CLEAR PATH TO DESCEND INTO THE UPR GREAT LAKES IN A NRLY FLOW. EXPECT DOUBLE DIGITS BLO ZERO TO REMAIN THE RULE OVER THE INTERIOR OF WEST AND CENTRAL COUNTIES UNDER GENERALLY CLEAR SKIES AND WRLY FLOW OVER THE NEXT FEW NIGHT WHILE HIGH TEMPS STRUGGLE TO REACH NEAR ZERO. WRLY FLOW WILL CONTINUE SOME LES OVER THE KEWEENAW PENINSULA AND ERN COUNTY SHORELINES SUN NIGHT ALTHOUGH FLOW BACKING MORE WSW SHOULD PUSH LES BANDS BACK OFF THE ERN COUNTY SHORELINES BY MON. POOR SNOW GROWTH SHOULD LIMIT ACCUMULATIONS TO 1 TO LOCALLY 4 INCHES SUN NIGHT INTO MON SO DO NOT ANTICIPATE HEADLINES FOR SNOW OR BLOWING SNOW. BY TUE...GFS...UKMET AND ECMWF ALL ADVERTISE ANOTHER SHORTWAVE DESCENDING DOWN ACROSS UPR MI REINFORCING THE ARCTIC AIR OVER THE REGION WITH 850 MB TEMPS DROPPING TO AROUND -25C OR COLDER BY LATE TUE INTO WED. TROFFING OVER LAKE SUPERIOR IS ENHANCED BY THIS SHORTWAVE AND COLDER AIR WHICH WILL IN TURN ENHANCE LOW-LVL CONVERGENCE OVER THE KEWEENAW PENINSULA AND ERN SHORELINE AREAS. LOOK FOR LES TO PICK UP OVER THESE AREAS FOR LATE TUE INTO WED. MODELS THEN POINT TO A TRANSITION IN THE PATTERN FOR LATE NEXT WEEK. OPERATIONAL 00Z ECMWF RUN WAS GENERALLY FAVORED BY NCEP AND FOLLOWED IT FOR DETAILS. TROF BEGINS TO TAKE SHAPE OVER THE WRN CONUS BY THE END OF THE WEEK AS RIDGING BEGINS TO MOVE INTO THE NRN PLAINS. MODERATING TEMPS OVER THE NRN PLAINS WILL GRADUALLY WORK INTO THE UPR GREAT LAKES BY THE END OF THE WEEK AS 850 MB TEMPS REBOUNDING TO AROUND -12C OR SO SHOULD HELP SHAKE BITTER COLD TEMPS FROM THE REGION. ARRIVAL OF SHORTWAVE AND ASSOC SFC LOW PRES SYSTEM FOR FRI INTO SAT WILL WARRANT LOW CHC POPS ACROSS THE AREA. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... WITH WNW FLOW OF VERY COLD AIR FCST TO PERSIST THRU SUN...EXPECT LTL CHG IN PREVAILING CONDITIONS AT BOTH SITES THIS FCST PD. AT CMX... LES/IFR TO LIFR VSBYS/IFR CIGS OCNL MVFR CIGS WL BE THE RULE WITH GUSTY WINDS AT TIMES CAUSING CONSIDERABLE BLOWING OF THE FINE SN FLAKES THAT WL EFFECTIVELY REDUCE VSBY. LOOK FOR CONDITIONS AT SAW TO BE VFR FOR THE MOST PART WITH LESS LK MODIFICATION THERE. SOME BKN SC/HI MVFR CIGS MAY FORM SUN AFTN WITHIN H85 THERMAL TROF AS WAS THE CASE ON SAT AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...THE FRONT OVER EASTERN LAKE SUPERIOR WILL REMAIN STATIONARY THROUGH MONDAY WHILE WEAKENING. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. ANOTHER LOW WILL LIFT OUT OF THE MIDDLE MISSISSIPPI RIVER VALLY THROUGH NORTHERN LOWER MICHIGAN LATE ON MONDAY AND TO SOUTHERN QUEBEC ON TUESDAY. ANOTHER HIGH PRESSURE SYSTEM DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY WILL MOVE INTO THE OHIO RIVER VALLEY AS A LOW DEVELOPS OVER THE LAKE SUPERIOR. COLD TEMPERATURES AND STRONG WINDS WILL PRODUCE CONSIDERABLE HEAVY FREEZING SPRAY THROUGH MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ001>003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002-004-005-009>014-084. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY LMZ221-248-250. && $$ SHORT TERM...DLG LONG TERM...VOSS AVIATION...KC MARINE...DLG mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 500 PM EST SAT JAN 19 2008 .SYNOPSIS/SHORT TERM (TONIGHT AND SUNDAY)... THE MAIN CONCERN WITH THIS FORECAST UPDATE IS THE POTENTIAL FOR LAKE EFFECT SNOWS AND WIND CHILLS TONIGHT AND SUNDAY. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN U.P. A RIDGE IS OVER THE PACIFIC NORTHWEST...WITH A WEAK RIDGE EXTENDING FROM WESTERN MONTANA NORTHWARD INTO ALBERTA. A WEAK SHORTWAVE SLIDING DOWN THE LEE OF THE RIDGE IS OVER THE WESTERN U.P. SURFACE ANALYSIS DEPICTS A 1032MB HIGH IN THE KANSAS CITY AREA WITH A RIDGE EXTENDING NORTHWEST INTO NORTHERN SASKATCHEWAN. A WEAK FRONTAL SYSTEM IS WASHING OUT OVER EASTERN LAKE SUPERIOR. A THERMAL TROUGH IS PRODUCING LAKE-850MB DELTA-T OVER LAKE SUPERIOR OF 29C. THE FRONT IS PRODUCING LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR. TOGETHER WITH THE SHORTWAVE ENERGY ARE GENERATING LAKE EFFECT SNOWS. THE ANTICYCLONIC AHEAD OF THE RIDGE IS CAUSING STRONG WEST AND NORTHWEST FLOW ACROSS THE AREA. THUS AREAS DOWNWIND OF LAKE SUPERIOR CONTINUE TO PRODUCE LAKE EFFECT SNOWS. SIGNIFICANT ACCUMULATION OF LES WILL CONTINUE THROUGH TONIGHT AS MORE WEAK SHORTWAVE SWEEP THROUGH THE AREA TONIGHT...AND THE DELTA-T REMAIN MORE THAN 29C. LOW LEVEL CONVERGENCE IS EXPECTED TO CONTINUE OVER LAKE SUPERIOR. THUS LITTLE CHANGE IN THE WEATHER CAN BE EXPECTED TONIGHT. THE LONGWAVE TROUGH WILL REMAIN OVER EASTERN CANADA ON SUNDAY. THE TROUGH THAT WAS OVER THE U.P. TODAY WILL ROTATE RAPIDLY INTO NEW ENGLAND AS WEAKER SHORTWAVE SWEEP THROUGH THE AREA. ANOTHER TROUGH WILL DEVELOP IN THE LEE OF THE PACIFIC RIDGE AND SLIDE INTO SOUTH CENTRAL CANADA. THE SURFACE HIGH OVER KANSAS CITY WILL MOVE EAST INTO THE WESTERN KENTUCKY AND THE SOUTHERN OHIO RIVER VALLEY. THE WEAK COLD FRONT WILL STILL STRETCH ACROSS EASTERN LAKE SUPERIOR. HEAVY LES CAN BE EXPECTED ALONG THE LAKE SUPERIOR SHORE WHICH IS WHAT IS IN THERE ALREADY. && .LONG TERM (SUNDAY NIGHT THROUGH NEXT SATURDAY)... MODELS INDICATE THAT ARCTIC AIRMASS COULD PERSIST INTO AT LEAST MIDWEEK AS BITTER COLD TEMPS AND WIND CHILLS REMAIN A CONCERN INTO THE EARLY PART OF NEXT WEEK. HEADLINES FOR WIND CHILLS WILL LIKELY NEED TO BE EXTENDED SUNDAY NIGHT INTO MON AND MAYBE EVEN INTO TUE AS VERY COLD PATTERN PERSISTS. AMPLIFIED UPR RIDGE OVER WESTERN CANADA IS ALLOWING POLAR AIR A CLEAR PATH TO DESCEND INTO THE UPR GREAT LAKES IN A NRLY FLOW. EXPECT DOUBLE DIGITS BLO ZERO TO REMAIN THE RULE OVER THE INTERIOR OF WEST AND CENTRAL COUNTIES UNDER GENERALLY CLEAR SKIES AND WRLY FLOW OVER THE NEXT FEW NIGHT WHILE HIGH TEMPS STRUGGLE TO REACH NEAR ZERO. WRLY FLOW WILL CONTINUE SOME LES OVER THE KEWEENAW PENINSULA AND ERN COUNTY SHORELINES SUN NIGHT ALTHOUGH FLOW BACKING MORE WSW SHOULD PUSH LES BANDS BACK OFF THE ERN COUNTY SHORELINES BY MON. POOR SNOW GROWTH SHOULD LIMIT ACCUMULATIONS TO 1 TO LOCALLY 4 INCHES SUN NIGHT INTO MON SO DO NOT ANTICIPATE HEADLINES FOR SNOW OR BLOWING SNOW. BY TUE...GFS...UKMET AND ECMWF ALL ADVERTISE ANOTHER SHORTWAVE DESCENDING DOWN ACROSS UPR MI REINFORCING THE ARCTIC AIR OVER THE REGION WITH 850 MB TEMPS DROPPING TO AROUND -25C OR COLDER BY LATE TUE INTO WED. TROFFING OVER LAKE SUPERIOR IS ENHANCED BY THIS SHORTWAVE AND COLDER AIR WHICH WILL IN TURN ENHANCE LOW-LVL CONVERGENCE OVER THE KEWEENAW PENINSULA AND ERN SHORELINE AREAS. LOOK FOR LES TO PICK UP OVER THESE AREAS FOR LATE TUE INTO WED. MODELS THEN POINT TO A TRANSITION IN THE PATTERN FOR LATE NEXT WEEK. OPERATIONAL 00Z ECMWF RUN WAS GENERALLY FAVORED BY NCEP AND FOLLOWED IT FOR DETAILS. TROF BEGINS TO TAKE SHAPE OVER THE WRN CONUS BY THE END OF THE WEEK AS RIDGING BEGINS TO MOVE INTO THE NRN PLAINS. MODERATING TEMPS OVER THE NRN PLAINS WILL GRADUALLY WORK INTO THE UPR GREAT LAKES BY THE END OF THE WEEK AS 850 MB TEMPS REBOUNDING TO AROUND -12C OR SO SHOULD HELP SHAKE BITTER COLD TEMPS FROM THE REGION. ARRIVAL OF SHORTWAVE AND ASSOC SFC LOW PRES SYSTEM FOR FRI INTO SAT WILL WARRANT LOW CHC POPS ACROSS THE AREA. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... PERSISTENCE IS THE WAY TO GO WITH THE TAF FORECAST THROUGH THE NEXT 24 HOURS AS GUIDANCE SHOWING THE PATTERN WILL CHANGE LITTLE. BASICALLY...NORTHWEST WINDS CONTINUE TO DRIVE ARCTIC AIR ACROSS LAKE SUPERIOR INTO UPPER MICHIGAN...WHICH WILL HELP MAINTAIN LAKE EFFECT SNOW SHOWERS WITH FINE SNOWFLAKES. THESE FINER SNOWFLAKES COMBINED WITH THE WIND HAVE KEPT CMX BOUNCING BETWEEN LIFR AND IFR FOR VSBY...AND IFR TO MVFR FOR CEILING FOR THE PAST 12 HOURS...AND THIS SHOULD CONTINUE THROUGH TONIGHT. AT SAW...LAKE EFFECT BANDS OFF WESTERN LAKE SUPERIOR CANNOT PENETRATE THAT FAR INLAND...THUS VFR CONDITIONS ARE FORECAST. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)...THE FRONT OVER EASTERN LAKE SUPERIOR WILL REMAIN STATIONARY THROUGH MONDAY WHILE WEAKENING. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. ANOTHER LOW WILL LIFT OUT OF THE MIDDLE MISSISSIPPI RIVER VALLY THROUGH NORTHERN LOWER MICHIGAN LATE ON MONDAY AND TO SOUTHERN QUEBEC ON TUESDAY. ANOTHER HIGH PRESSURE SYSTEM DEVELOP OVER THE CENTRAL PLAINS ON TUESDAY WILL MOVE INTO THE OHIO RIVER VALLEY AS A LOW DEVELOPS OVER THE LAKE SUPERIOR. COLD TEMPERATURES AND STRONG WINDS WILL PRODUCE CONSIDERABLE HEAVY FREEZING SPRAY THROUGH MONDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ001>003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002-004-005-009>014-084. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY LMZ221-248-250. && $$ SHORT TERM...DLG LONG TERM...VOSS AVIATION/MARINE...DLG mi AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 1223 PM EST SAT JAN 19 2008 .DISCUSSION... MAIN FORECAST CONCERNS ARE LES TRENDS ALONG WITH TEMPS/WIND CHILLS. WATER VAPOR IMAGERY AND RUC SHOWING A LONGWAVE TROUGH OVER EASTERN CANADA DRAPED SOUTHWEST THROUGH THE UPPER GREAT LAKES...THEN INTO SOUTH CENTRAL PLAINS...AND A RIDGE ALONG THE PACIFIC COAST. WEAK SHORTWAVES ARE SLIDING DOWN THE LEE OF THE RIDGE AND TRACKING THROUGH THE AREA. SURFACE ANALYSIS DEPICTS A POWERFUL RIDGE EXTENDING FROM TEXAS NORTH THROUGH THE NORTHERN PLAINS INTO CENTRAL CANADA. THIS CONTINUES TO DRAW VERY COLD AIR FROM CENTRAL CANADA INTO THE UPPER GREAT LAKES. A WEAK STATIONARY FRONT EXTENDS FROM THE LOWER GREAT LAKES INTO EASTERN LAKE SUPERIOR. THE COLD AIR AND WEAK FRONTAL SYSTEM CONTINUES TO PRODUCE LAKE EFFECTS SNOWS OVER EASTERN PART OF THE CWA AND ALONG WEST COAST OF THE CWA FROM ONTONAGON NORTHEAST THROUGH THE KEWEENAW PENINSULA. THIS AFTERNOON...THE LONGWAVE TROUGH WILL REMAIN NEARLY STATIONARY OVER THE FORECAST AREA AS WEAK SHORTWAVE SWEEP THROUGH THE BASE OF THE TROUGH. ONE OF THE SHORTWAVE WILL MOVE INTO THE WEST END OF THE U.P. BY LATE AFTERNOON. THE SURFACE RIDGE WILL SHIFT ONLY A LITTLE TOWARDS THE MIDDLE MISSISSIPPI RIVER VALLEY WHILE THE FRONTAL SYSTEM REMAINS OVER LAKE SUPERIOR. THE WATER-850MB DELTA-T WILL BE AROUND 28C OR GREAT THROUGH THE AFTERNOON. THIS INDICATES LOW LEVEL INSTABILITY WILL REMAIN STRONG ENOUGH TO KEEP LAKE EFFECT SNOWS GOING ACROSS THE AREA. THE FRONTAL SYSTEM WILL KEEP STRONG LOW LEVEL CONVERGENCE OVER LAKE SUPERIOR. REPORTS FROM SPOTTERS INDICATE AROUND 5+ INCHES SO FAR OVER ALGER AND NORTHERN LUCE COUNTIES. THUS PLAN TO KEEP THE WARNING GOING FOR NOW AND ADVISORY ELSEWHERE. TEMPERATURES ARE WARMING A BIT...HOWEVER...THE WINDS ARE INCREASING WITH THE APPROACH OF THE SHORTWAVE WHICH WILL KEEP THE LOW WIND CHILLS GOING THIS AFTERNOON. DO NOT PLAN TO UPDATE. TONIGHT...LOW LEVEL WINDS ARE EXPECTED TO VEER AGAIN THIS EVENING IN THE WAKE OF THE MANITOBA SHORTWAVE. HOWEVER...THE COMBINATION OF STRENGTHENING LAND BREEZES/LAKE INDUCED TROFFING AND THE APPROACH OF ANOTHER SHRTWV WILL KEEP WINDS MAINLY FROM THE WNW. THE STRONGER LOW LEVEL CONV WILL FOCUS MAINLY EAST OF MUNISING AND NEAR M-38. ADDITIONAL AMOUNTS OF 2 TO 6 INCHES EAST AND 1 TO 3 INCHES WEST ARE EXPECTED. AIDED BY LAKE TROFFING...THE GRADIENT WILL REMAIN STRONG ENOUGH TONIGHT TO KEEP WINDS NEAR 10 MPH. COMBINED WITH TEMPS FALLING INTO THE -5 TO -17 RANGE...WIND CHILL VALUES WILL AGAIN FALL TO TH -25 TO -35 RANGE. SOME VALUES INTO THE WARNING RANGE ARE POSSIBLE BUT MAY BE MARGINAL GIVEN BALANCE BETWEEN RADIATIONAL COOLING/MIXING OVER INLAND LOCATIONS. HOWEVER...UPGRADE TO WARNING MAY BE NEEDED. SUN AND INTO MON...PERSISTENT WNW FLOW AND LAKE INDUCED WILL KEEP LES GOING FOR THE WEST(NORTH OF M-28)AND EAST (EAST OF MUNISING) WITH GRADUAL BACKING TREND ALLOWING LES BANDS TO LIFT OFFSHORE IN THE EAST AND FOCUS INTO THE KEWEENAW. LIMITING FACTORS WITH SNOWFLAKE GROWTH REMAIN. SO...OVERALL ACCUMULATIONS WILL MAINLY BE IN THE 2-5 INCH PER 12 HOURS EAST AND 1-3 INCHES WEST. TEMPERATURES ARE EXPECTED TO AGAIN FALL TO -10 TO -20 INLAND. LIGHTER WINDS BLO 10 MPH WILL KEEP WIND CHILL VALUES FROM BEING QUITE AS SEVERE. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... PERSISTENCE IS THE WAY TO GO WITH THE TAF FORECAST THROUGH THE NEXT 24 HOURS AS GUIDANCE SHOWING THE PATTERN WILL CHANGE LITTLE. BASICALLY...NORTHWEST WINDS CONTINUE TO DRIVE ARCTIC AIR ACROSS LAKE SUPERIOR INTO UPPER MICHIGAN...WHICH WILL HELP MAINTAIN LAKE EFFECT SNOW SHOWERS WITH FINE SNOWFLAKES. THESE FINER SNOWFLAKES COMBINED WITH THE WIND HAVE KEPT CMX BOUNCING BETWEEN LIFR AND IFR FOR VSBY...AND IFR TO MVFR FOR CEILING FOR THE PAST 12 HOURS...AND THIS SHOULD CONTINUE THROUGH TONIGHT. AT SAW...LAKE EFFECT BANDS OFF WESTERN LAKE SUPERIOR CANNOT PENETRATE THAT FAR INLAND...THUS VFR CONDITIONS ARE FORECAST. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRESSURE TROUGH OVER EASTERN LAKE SUPERIOR WILL KEEP REMAIN STATIONARY THROUGH MONDAY. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TODAY AND TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ001>003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002-004-005-009>011-084. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY LMZ221-248-250. && $$ SYNOPSIS AND THIS AFTERNOON...DLG REST OF DISCUSSION...JLB AVIATION/MARINE...AJ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 650 AM EST SAT JAN 19 2008 UPDATED AVIATION SECTION FOR 12Z TAF ISSUANCE. .DISCUSSION... MAIN FCST CONCERNS ARE LES TRENDS ALONG WITH TEMPS/WIND CHILLS. WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH DOMINATING CNTRL AND ERN NOAM. ONE SHORTWAVE TROUGH EMBEDDED IN THE CYCLONIC FLOW WAS MOVING THROUGH CNTRL UPPER MI. ANOTHER UPSTREAM SHRTWV WAS LOCATED NE OF LAKE WINNIPEG. AT THE SFC...LAKE NW FLOW PREVAILED BTWN ARCTIC HIGH PRES INTO THE PLAINS AND WEAK TROFFING FROM QUEBEC INTO THE GREAT LAKES. LAKE INDUCED TROFFING WAS EVIDENT ACROSS SRN LAKE SUPERIOR SUPPORTED BY VERY LARGE LAND/LAKE TEMP DIFFERENCE. RADAR INDICATED THAT THE DOMINANT BAND INTO THE NE CWA LAKE SUPERIOR SHORELINE HAD TRANSITIONED TO WEAKER MULTIPLE WIND PARALLEL BANDS AS WINDS VEERED TO 320 CBL FLOW. OTHERWISE...VERY COLD AIR HAS MOVED INTO THE REGION WITH TEMPS OVER NRN MN AND WRN ONTARIO WITH 850 MB TEMPS AOB -30C. SFC TEMPS WERE INTO THE -20 TO -25 RANGE AND READINGS FROM AROUND ZERO NEAR LAKE SUPERIOR TO -15 BELOW OVER INLAND PORTIONS OF WEST UPPER MI. THE COLD AIR ALONG WITH WINDS OF 5 TO 15 MPH HAVE DROPPED WIND CHILL VALUES INTO THE ADVISORY RANGE FROM -20 TO -35. TODAY...EXPECT WINDS TO GRADUALLY BACK WITH THE APPROACH OF THE MANITOBA SHORTWAVE. THE NAM AND LCL HIGH RES WRF/ARW THAT HAVE HANDLED EFFECTS OF LAKE TROFFING REASONABLY WELL SUGGEST THAT HEAVIER LES BANDS WILL AGAIN SHIFT CLOSER TO THE SHORELINE EAST OF MUNISING IN THE ERN CWA. TEMP PROFILE...WITH ONLY A SHALLOW OR NO LAYER ABOVE -17C WERE NOT FAVORABLE FOR DENDRITIC SNOWFLAKE GROWTH AND SHOULD LIMIT ACCUMULATIONS...DESPITE VERY LARGE INSTABILITY (850 MB TEMPS TO AROUND -26C). HOWEVER...ACCUMULATIONS IN THE 3 TO 7 INCH RANGE ARE STILL POSSIBLE. OVER THE WEST...THE SHORTER FETCH AND EVEN COLDER/DRIER AIR WILL KEEP ACCUMULATIONS MAINLY IN THE 1 TO 4 INCH RANGE. MDLS SHOW THE MOST FAVORABLE LOW LEVEL CONV BTWN ONTONAGON...M-38 AND HOUGHTON. THE WINDS NEAR THE LAKE INTO THE 15 TO 25 MPH RANGE ALONG WITH THE FINE SNOWFLAKES WILL LIMIT VSBYS AT TIMES TO AROUND 1/4SM. WIND CHILL VALUES WILL MODERATE WITH DIURNAL WARMING BUT WILL STILL REMAIN CLOSE TO ADVISORY RANGE DURING THE AFTERNOON FROM -15 TO -25. TONIGHT...LOW LEVEL WINDS ARE EXPECTED TO VEER AGAIN THIS EVENING IN THE WAKE OF THE MANITOBA SHORTWAVE. HOWEVER...THE COMBINATION OF STRENGTHENING LAND BREEZES/LAKE INDUCED TROFFING AND THE APPROACH OF ANOTHER SHRTWV WILL KEEP WINDS MAINLY FROM THE WNW. THE STRONGER LOW LEVEL CONV WILL FOCUS MAINLY EAST OF MUNISING AND NEAR M-38. ADDITIONAL AMOUNTS OF 2 TO 6 INCHES EAST AND 1 TO 3 INCHES WEST ARE EXPECTED. AIDED BY LAKE TROFFING...THE GRADIENT WILL REMAIN STRONG ENOUGH TONIGHT TO KEEP WINDS NEAR 10 MPH. COMBINED WITH TEMPS FALLING INTO THE -5 TO -17 RANGE...WIND CHILL VALUES WILL AGAIN FALL TO TH -25 TO -35 RANGE. SOME VALUES INTO THE WARNING RANGE ARE POSSIBLE BUT MAY BE MARGINAL GIVEN BALANCE BETWEEN RADIATIONAL COOLING/MIXING OVER INLAND LOCATIONS. HOWEVER...UPGRADE TO WARNING MAY BE NEEDED. SUN AND INTO MON...PERSISTENT WNW FLOW AND LAKE INDUCED WILL KEEP LES GOING FOR THE WEST(NORTH OF M-28)AND EAST (EAST OF MUNISING) WITH GRADUAL BACKING TREND ALLOWING LES BANDS TO LIFT OFFSHORE IN THE EAST AND FOCUS INTO THE KEWEENAW. LIMITING FACTORS WITH SNOWFLAKE GROWTH REMAIN. SO...OVERALL ACCUMULATIONS WILL MAINLY BE IN THE 2-5 INCH PER 12 HOURS EAST AND 1-3 INCHES WEST. TEMPERATURES ARE EXPECTED TO AGAIN FALL TO -10 TO -20 INLAND. LIGHTER WINDS BLO 10 MPH WILL KEEP WIND CHILL VALUES FROM BEING QUITE AS SEVERE. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... PERSISTENCE IS THE WAY TO GO WITH THE TAF FORECAST THROUGH THE NEXT 24 HOURS AS THE PATTERN STAYS MAINLY THE SAME. BASICALLY...NORTHWEST WINDS CONTINUE TO DRIVE ARCTIC AIR ACROSS LAKE SUPERIOR INTO UPPER MICHIGAN...WHICH WILL HELP MAINTAIN LAKE EFFECT SNOW SHOWERS WITH FINE SNOWFLAKES. THESE FINER SNOWFLAKES COMBINED WITH THE WIND HAVE KEPT CMX BOUNCING BETWEEN LIFR AND IFR FOR VSBY...AND IFR TO MVFR FOR CEILING FOR THE PAST 12 HOURS...AND THIS SHOULD CONTINUE THROUGH TONIGHT. AT SAW...LAKE EFFECT BANDS OFF WESTERN LAKE SUPERIOR CANNOT PENETRATE THAT FAR INLAND...THUS VFR CONDITIONS ARE FORECAST. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRESSURE TROUGH OVER EASTERN LAKE SUPERIOR WILL KEEP REMAIN STATIONARY THROUGH MONDAY. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TODAY AND TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO FALL BELOW 20 KT. HEAVY FREEZING SPRAY WILL CONTINUE THROUGH SUNDAY NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ001>003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002-004-005-009>011-084. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY LMZ221-248-250. && $$ DISCUSSION...JLB AVIATION/MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 500 AM EST SAT JAN 19 2008 .DISCUSSION... MAIN FCST CONCERNS ARE LES TRENDS ALONG WITH TEMPS/WIND CHILLS. WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH DOMINATING CNTRL AND ERN NOAM. ONE SHORTWAVE TROUGH EMBEDDED IN THE CYCLONIC FLOW WAS MOVING THROUGH CNTRL UPPER MI. ANOTHER UPSTREAM SHRTWV WAS LOCATED NE OF LAKE WINNIPEG. AT THE SFC...LAKE NW FLOW PREVAILED BTWN ARCTIC HIGH PRES INTO THE PLAINS AND WEAK TROFFING FROM QUEBEC INTO THE GREAT LAKES. LAKE INDUCED TROFFING WAS EVIDENT ACROSS SRN LAKE SUPERIOR SUPPORTED BY VERY LARGE LAND/LAKE TEMP DIFFERENCE. RADAR INDICATED THAT THE DOMINANT BAND INTO THE NE CWA LAKE SUPERIOR SHORELINE HAD TRANSITIONED TO WEAKER MULTIPLE WIND PARALLEL BANDS AS WINDS VEERED TO 320 CBL FLOW. OTHERWISE...VERY COLD AIR HAS MOVED INTO THE REGION WITH TEMPS OVER NRN MN AND WRN ONTARIO WITH 850 MB TEMPS AOB -30C. SFC TEMPS WERE INTO THE -20 TO -25 RANGE AND READINGS FROM AROUND ZERO NEAR LAKE SUPERIOR TO -15 BELOW OVER INLAND PORTIONS OF WEST UPPER MI. THE COLD AIR ALONG WITH WINDS OF 5 TO 15 MPH HAVE DROPPED WIND CHILL VALUES INTO THE ADVISORY RANGE FROM -20 TO -35. TODAY...EXPECT WINDS TO GRADUALLY BACK WITH THE APPROACH OF THE MANITOBA SHORTWAVE. THE NAM AND LCL HIGH RES WRF/ARW THAT HAVE HANDLED EFFECTS OF LAKE TROFFING REASONABLY WELL SUGGEST THAT HEAVIER LES BANDS WILL AGAIN SHIFT CLOSER TO THE SHORELINE EAST OF MUNISING IN THE ERN CWA. TEMP PROFILE...WITH ONLY A SHALLOW OR NO LAYER ABOVE -17C WERE NOT FAVORABLE FOR DENDRITIC SNOWFLAKE GROWTH AND SHOULD LIMIT ACCUMULATIONS...DESPITE VERY LARGE INSTABILITY (850 MB TEMPS TO AROUND -26C). HOWEVER...ACCUMULATIONS IN THE 3 TO 7 INCH RANGE ARE STILL POSSIBLE. OVER THE WEST...THE SHORTER FETCH AND EVEN COLDER/DRIER AIR WILL KEEP ACCUMULATIONS MAINLY IN THE 1 TO 4 INCH RANGE. MDLS SHOW THE MOST FAVORABLE LOW LEVEL CONV BTWN ONTONAGON...M-38 AND HOUGHTON. THE WINDS NEAR THE LAKE INTO THE 15 TO 25 MPH RANGE ALONG WITH THE FINE SNOWFLAKES WILL LIMIT VSBYS AT TIMES TO AROUND 1/4SM. WIND CHILL VALUES WILL MODERATE WITH DIURNAL WARMING BUT WILL STILL REMAIN CLOSE TO ADVISORY RANGE DURING THE AFTERNOON FROM -15 TO -25. TONIGHT...LOW LEVEL WINDS ARE EXPECTED TO VEER AGAIN THIS EVENING IN THE WAKE OF THE MANITOBA SHORTWAVE. HOWEVER...THE COMBINATION OF STRENGTHENING LAND BREEZES/LAKE INDUCED TROFFING AND THE APPROACH OF ANOTHER SHRTWV WILL KEEP WINDS MAINLY FROM THE WNW. THE STRONGER LOW LEVEL CONV WILL FOCUS MAINLY EAST OF MUNISING AND NEAR M-38. ADDITIONAL AMOUNTS OF 2 TO 6 INCHES EAST AND 1 TO 3 INCHES WEST ARE EXPECTED. AIDED BY LAKE TROFFING...THE GRADIENT WILL REMAIN STRONG ENOUGH TONIGHT TO KEEP WINDS NEAR 10 MPH. COMBINED WITH TEMPS FALLING INTO THE -5 TO -17 RANGE...WIND CHILL VALUES WILL AGAIN FALL TO TH -25 TO -35 RANGE. SOME VALUES INTO THE WARNING RANGE ARE POSSIBLE BUT MAY BE MARGINAL GIVEN BALANCE BETWEEN RADIATIONAL COOLING/MIXING OVER INLAND LOCATIONS. HOWEVER...UPGRADE TO WARNING MAY BE NEEDED. SUN AND INTO MON...PERSISTENT WNW FLOW AND LAKE INDUCED WILL KEEP LES GOING FOR THE WEST(NORTH OF M-28)AND EAST (EAST OF MUNSING) WITH GRADUAL BACKING TREND ALLOWING LES BANDS TO LIFT OFFSHORE IN THE EAST AND FOCUS INTO THE KEWEENAW. LIMITING FACTORS WITH SNOWFLAKE GROWTH REMAIN. SO...OVERALL ACCUMULATIONS WILL MAINLY BE IN THE 2-5 INCH PER 12 HOURS EAST AND 1-3 INCHES WEST. TEMPERATURES ARE EXPECTED TO AGAIN FALL TO -10 TO -20 INLAND. LIGHTER WINDS BLO 10 MPH WILL KEEP WIND CHILL VALUES FROM BEING QUITE AS SEVERE. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... LIFR CONDITIONS CAN BE EXPECTED AT CMX THE REST OF TONIGHT WITH BLOWING SNOW CAUSING VISIBILITY ISSUES AND THEN CONDITIONS SHOULD IMPROVE A BIT TO IFR FOR VISIBILITY ON SAT AGAIN WITH BLOWING SNOW. WINDS WILL INCREASE A BIT SAT EVENING AND VIS SHOULD GO DOWN AGAIN TO LIFR WITH BLOWING SNOW. FOR SAW...VFR CONDITIONS EXPECTED TO CONTINUE WITH W TO NW WINDS KEEPING THE LAKE EFFECT BANDS WELL NORTH OF THE AREA. JUST A FEW LAKE EFFECT CLOUDS OFF WESTERN LAKE SUPERIOR WILL CONTINUE TO AFFECT THE SITE THROUGH THE PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... A LOW PRESSURE TROUGH OVER EASTERN LAKE SUPERIOR WILL KEEP REMAIN STATIONARY THROUGH MONDAY. W-NW FLOW WILL REMAIN IN THE 15 TO 30 KT RANGE DURING THIS PERIOD...WITH THE STRONGEST WINDS OCCURRING TODAY AND TONIGHT. A RIDGE OF HIGH PRESSURE WILL CROSS LAKE SUPERIOR MONDAY NIGHT INTO TUESDAY...CAUSING WINDS TO BACK MORE TOWARDS THE WEST...THOUGH SPEEDS REMAIN BETWEEN 15 AND 25 KT. A COLD FRONT PASSAGE IS EXPECTED TUE NIGHT. BEHIND THIS FRONT...LOOK FOR WINDS TO FALL BELOW 20 KT. HEAVY FREEZING SRPAY WILL CONTINUE THROUGH SUNDAY NIGHT DUE TO THE STRONG WINDS AND PERSISTENT ARCTIC AIRMASS. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ001>003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUNDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SUNDAY FOR MIZ006-007. WIND CHILL ADVISORY UNTIL 1 PM EST /12 PM CST/ SUNDAY FOR MIZ002-004-005-009>011-084. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 4 AM EST MONDAY LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 PM EST SUNDAY LMZ221-248-250. && $$ DISCUSSION...JLB AVIATION/MARINE...AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BILLINGS MT 309 AM MST SUN JAN 20 2008 .SHORT TERM...VALID FOR TDY AND MON... OVERALL THE CURRENT WINTER HEADLINES ARE IN GOOD SHAPE AND WILL MAKE NO CHANGES. A COUPLE OF MODEL ERRORS WITH THIS EVENT ARE BECOMING APPARENT. CIRCULATION IN NE WASHINGTON NOT INITIALLY HANDLED BY MODELS WELL...AND IS A FOCUS FOR SOME PRETTY GOOD ASCENT TO OUR WEST STILL. AS A RESULT WE ARE SEEING DIFFLUENT SIGNATURE ON WATER VAPOR IMAGERY SPREAD INTO OUR AREA JUST NOW. OTHER ERROR IS THAT THE MODELS WERE DRIVING THE COLD AIR SOUTH INTO OUR AREA TOO QUICKLY. TEMPS HAVE NOT FALLEN AT ALL OVER THE PAST FEW HOURS...AND IN FACT HAVE WARMED IN SOME CASES. THIS IN RESPONSE TO INCREASING WARM ADVECTION AS STRONGER DYNAMICS NEAR US. NAM/RUC SEEM TO HAVE DECENT HANDLE ON THESE ITEMS NOW...AND SHOW PERIOD OF MID LEVEL WARM ADVECTION INTO OUR AREA EARLY THIS MORNING. WITH THIS ALONG WITH DEEPENING DENDRITIC LAYER WOULD EXPECT A FEW HOURS OF ENHANCED SNOWFALL THIS MORNING...RATES POSSIBLY NEAR AN INCH PER HOUR FOR A SHORT TIME...STARTING ACROSS CENTRAL PARTS INCLUDING BILLINGS THEN FINALLY PUSHING SOUTH TO THE FOOTHILLS BY 15Z OR SO. INFRARED IMAGERY INDEED SHOWS COLDER TOPS WORKING IN FROM THE WEST...IN LINE WITH THESE THOUGHTS. SO...HAVE UPPED EXPECTED SNOW AMOUNTS TODAY TO GENERALLY 3 TO 5 INCHES FROM BILLINGS SOUTHWARD. SLOWER NATURE OF SYSTEM SHOULD ALSO ALLOW FOR WARM ADVECTION TO REACH OUR SE ZONES. HAVE RAISED POPS AND SNOW AMOUNTS IN THIS AREA...FROM LAME DEER TO EKALAKA...AND SEE NO REASON TO CHANGE CURRENT ADVISORY IN THIS AREA. WINDS GUSTING PRETTY GOOD IN NOTORIOUS PLACES SUCH JUDITH GAP...LIVINGSTON AND ABERDEEN HILL...AND BLOWING/DRIFTING SNOW IS NO DOUBT WREAKING HAVOC ON AREA ROADS. WILL CONTINUE THE HIGH POPS ACROSS OUR SOUTHERN TIER FOR TONIGHT... BUT COLD AIR SHOULD FINALLY SURGE IN BEFORE THEN THUS DIMINISHING THE SNOW RATIOS. NAM CONTINUES TO SHOW UPSLOPE LIGHT PCPN CONTINUING INTO MON. GIVEN HOW THE SYSTEM HAS STALLED ALREADY THINK EXPANDING SOME LOW POPS FOR LIGHT SNOW OR FLURRIES NOT A BAD IDEA...AT LEAST FOR MON MORNING. SUBSIDENCE WITH UPPER RIDGE WILL FINALLY DRY THINGS OUT ACROSS THE AREA LATE MON AND MON NITE. WINDS NOT DOING MUCH AT BAKER...AND TEMPS JUST A BIT BELOW ZERO ANYWAY... SO WILL CANCEL THE WIND CHILL ADVISORY FOR FALLON COUNTY. SHOULD SEE SOME INCREASED WIND AS THE DAY GOES AS COLD ADVECTION PICKS BACK UP. WIND CHILLS SHOULD STAY ABOVE CRITERIA THOUGH UNTIL POSSIBLY TONIGHT. WILL LET DAY SHIFT MAKE THAT CALL. NAM/GFS VERY DIFFERENT WITH REGARD TO WHEN SFC RIDGE WILL GIVE WAY TO CHINOOKING. GFS BEGINS THE WSW WINDS DURING THE DAY ON MONDAY WHEREAS THE NAM HOLDS IT OFF TIL MON NIGHT. HAVE WENT WITH A COMPROMISE HERE...SIMILAR TO WHAT THE SREF SHOWS. EITHER WAY SHOULD SEE WINDS LATE MON NITE INCREASE TO THE POINT THAT BLOWING SNOW AND POSSIBLY WIND CHILLS WILL BE A CONCERN. HAVE PAINTED SOME BLSN IN OUR WESTERN PARTS 06-12Z TUE. AS FOR TEMPS...HAVE TWEAKED EXPECTED HIGHS UP A BIT TODAY. HIGHS WILL BE ACHIEVED EARLY WITH FALLING TEMPS THEREAFTER. COLD NIGHT TONIGHT BUT WITH CLOUD COVER AROUND THEY SHOULD NOT FALL TOO FAR...GENERALLY 5 TO 15 BELOW. HAVE LOWERED EXPECTED HIGHS A BIT MON AS COLDEST AIR WILL BE RIGHT OVER US...AGAIN A COMPROMISE BETWEEN THE NAM AND GFS HERE...HIGHS MAINLY SINGLE DIGITS. JKL .LONG TERM...VALID FOR TUE...WED...THU...FRI...SAT... AS THE WEEKEND SYSTEM PUSHES SOUTH OF THE AREA TUESDAY WILL SEE A NORTHERLY FLOW ALOFT MOVE INTO MONTANA. A CLIPPER MOVING RAPIDLY SOUTHWARD IN THIS FLOW WILL BRING A REVERSAL TO DOWNSLOPE WINDS EARLY ON TUESDAY WITH CONCERNS FOR BLOWING SNOW FROM BILLINGS WEST AS LOTS OF NEW POWDERY SNOW WILL COVER THE AREA. TEMPERATURES WILL MODERATE WITH THE DOWNSLOPE BUT GIVEN SO MUCH SNOW TEMPERATURES WILL BE TRICKY. THE CLIPPER MOVES INTO THE DAKOTAS AND EASTERN MONTANA TUESDAY NIGHT AND AMPLIFIES THE CYCLONIC FLOW ALOFT BRINGING A RISK FOR ADDITIONAL SNOWFALL. COLD AIR REINFORCES A BIT BEHIND THE SYSTEM BUT CLOUD COVER SHOULD KEEP TUESDAY NIGHT TEMPS FROM BEING TOO COLD. WEDNESDAY AND THURSDAY LOOK DRY AND STABLE WITH WEAK DOWNSLOPE RESIDENT THROUGH THE PERIOD. HOW FAR EAST THE DOWNSLOPE PLAYS A ROLE WILL BE A BIG FACTOR IN HOW MUCH MODERATION OCCURS WITH EASTERN MONTANA LIKELY STAYING IN THE CHILL. FOR FRIDAY THE REMNANTS OF THE WEEKEND STORM SYSTEM THAT SLID ACROSS NORTHERN CALIFORNIA BEGINS TO EJECT IN A SOUTHWESTERLY FLOW ALOFT ACROSS THE AREA. THIS WILL TURN THE FLOW ALOFT CYCLONIC BUT MAIN FORCING LOOKS TO BE SOUTH AND WEST OF MONTANA. MODELS DO PROG WEAK CYCLOGENESIS ACROSS THE AREA WHICH COULD BRING A PERIOD OF SNOW BUT MODELS ARE NOT IN AGREEMENT TO THE DEPTH OF THIS SYSTEM SO CONFIDENCE AT THIS POINT IS LOW. STRONGER SYSTEM MOVES ACROSS THE EASTERN PACIFIC TO THE GULF OF ALASKA FOR NEXT WEEKEND WITH A STRONG FLOW ALOFT INTO THE PACIFIC NORTHWEST. THIS WILL BRING AN OROGRAPHIC PRECIPITATION PATTERN FOR THE MOUNTAINS AND STRONGER DOWNSLOPING AND MODERATIONS. BORSUM && .AVIATION... SNOW WILL CONTINUE ACROSS MOST OF THE AREA INTO SUNDAY NIGHT. PORTIONS OF SOUTHEAST MONTANA WILL SEE SLIGHTLY BETTER CONDITIONS...BUT THE REMAINDER OF THE AREA WILL SEE IFR TO LIFR CONDITIONS UNTIL SUNDAY EVENING. BORSUM && .PRELIMINARY POINT TEMP/POPS... TDY MON TUE WED THU FRI SAT ------------------------------------------------------- BIL 013 905/005 904/019 010/022 013/026 012/030 017/029 +/S 91/M 00/Q 30/B 00/N 11/B 22/S LVM 013 908/003 907/020 007/025 016/029 017/030 023/028 +/S 92/S 01/Q 30/B 00/N 21/B 23/S HDN 013 906/005 908/018 006/022 008/022 007/028 012/029 +/S 81/M 00/Q 40/B 00/B 11/B 21/B MLS 012 913/005 910/016 003/016 004/024 004/025 008/026 4/S 20/U 03/S 30/B 00/B 11/B 11/B 4BQ 011 910/004 914/018 002/019 003/023 003/024 007/026 9/S 71/M 00/B 30/B 00/B 11/B 11/B BHK 007 918/001 914/013 901/016 000/020 001/023 005/025 2/S 20/U 02/S 30/B 00/B 11/B 12/S SHR 015 905/004 911/015 002/021 005/024 005/026 009/026 +/S +3/S 00/B 41/M 00/B 11/B 22/S && .BYZ WATCHES/WARNINGS/ADVISORIES... MT...WINTER STORM WARNING IN EFFECT UNTIL 11 PM MST THIS EVENING FOR ZONES 28-29-34-35-40>42-57-63-68. SNOW AND BLOWING SNOW ADVISORY IN EFFECT UNTIL 5 PM MST THIS AFTERNOON FOR ZONES 30>32-36-37-58. WINTER STORM WARNING IN EFFECT UNTIL 5 AM MST MONDAY FOR ZONES 38-39-56-64>67. WY...WINTER STORM WARNING IN EFFECT UNTIL 5 AM MST MONDAY FOR ZONES 98-99. && $$ WEATHER.GOV/BILLINGS mt AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 1015 AM EST SAT JAN 19 2008 .SYNOPSIS... LOW PRESSURE ACROSS THE NORTHERN GULF OF MEXICO WILL MOVE OFF THE SOUTHEAST UNITED STATES COAST TODAY. THE LOW WILL INTENSIFY AS IT MOVES RAPIDLY TO THE NORTHEAST ACROSS THE OFFSHORE WATERS OF THE CAROLINAS BY THIS EVENING. ARCTIC HIGH PRESSURE WILL BUILD INTO THE CAROLINAS SUNDAY THROUGH MONDAY. A COASTAL TROUGH MAY DEVELOP OFFSHORE ON TUESDAY BEFORE BEING SWEPT AWAY BY A STRONG COLD FRONT TUESDAY NIGHT. HIGH PRESSURE TO BUILD IN FOR WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 10 AM SATURDAY...ISENTROPIC LIFT LEADING TO A WIDESPREAD AREA OF RAINFALL ACROSS THE REGION THIS MORNING. LOW PRESSURE IS MOVING INTO THE NE GULF OF MEXICO AND WILL CONTINUE TO LIFT NE TO OFF THE SE STATES THIS AFTERNOON. THE LOW WILL PULL AWAY FROM THE AREA THIS EVENING...THEN CHANCES FOR PRECIPITATION WILL DIMINISH FROM W TO E ACROSS THE AREA. PRECIP WILL LIKELY COME TO AN END BY MIDNIGHT INLAND...AND A COUPLE HOURS LATER ALONG THE COAST. THE POTENTIAL CONTINUES FOR A MIX OF PRECIPITATION...POSSIBLY CHANGING TO ALL SNOW AS THE PRECIP SHIELD EXITS THE AREA. PLAN TO CONTINUE WITH THE WINTER WEATHER ADVISORY ACROSS THE NORTHWESTERN TIER ZONES WHERE THERE IS A HIGHER CHANCE OF SEEING ACCUMULATING SNOW (UP TO AN INCH). COULD SEE SOME TRACE AMOUNTS FARTHER E AS THE PRECIP EXITS. COLD TEMPERATURES WILL SPREAD ACROSS THE FORECAST AREA OVERNIGHT AND ANY RESIDUAL MOISTURE ON THE ROADWAYS MAY CREATE SLICK CONDITIONS INTO SUNDAY MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...ARCTIC AIR MASS BUILDS IN SUN AS SFC CYCLONE MOVING AWAY FROM THE REGION DEEPENS AND DEEP UPPER TROF SWINGS THROUGH. 1000-500 THICKNESS VALUES DROP INTO THE 520S AND 850 TEMPS DROP BELOW -10. UPPER PATTERN QUICKLY BECOMES ZONAL WITH SFC HIGH MOVING OFFSHORE LATE SUN INTO MON AND RETURN FLOW STARTING MON NIGHT. TEMPERATURES WILL REMAIN WELL BELOW CLIMO...STRUGGLING TO REACH 40 ON SUN AND FALLING INTO THE TEENS/LOW 20S SUN NIGHT. SLIGHT WARM UP ON MON...WITH TEMPS BARELY HITTING 40...THOUGH PARTIAL THICKNESS VALUES SUGGEST TEMPS MAY NOT MAKE IT TO 40 IN MANY AREAS. TEMPS START TO REBOUND MON NIGHT AS SRLY FLOW STARTS TO DEVELOP AND COASTAL TROF BEGINS TAKING SHAPE. INCREASING CLOUD COVER MON NIGHT WILL HELP KEEP TEMPS CLOSE TO CLIMO. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM SATURDAY...WEAK WARM AIR ADVECTION ON TUESDAY AHEAD OF A COLD FRONT SHOULD BRING TEMPS TO OR SLITELY ABOVE NORMAL. THAT MAY BECOME THE WARMEST DAY OF THE EXTENDED PERIOD WITH THE MAJORITY OF THE LONG TERM FEATURING TEMPS BELOW NORMAL WITH THE LATEST MEX MOS GUIDANCE HOT OFF THE PRESS ILLUSTRATING THIS. VERY ACTIVE WEEK AND PROGRESSIVE PATTERN CONTINUES. GFS MODEL SEEMS OVERZEALOUS WITH MOISTURE WITH THE COLD FRONT ON TUESDAY AND AS A RESULT WILL STAY ON THE LOW CHANCE SIDE FOR PRECIP. BRIEF REPRIEVE ON WEDNESDAY B4 NEXT PCPN EVENT. WED NITE INTO THU NIGHT FEATURES AN OVERRUNING TYPE EVENT WITH LOW PRESSURE FROM THE GULF MOVING NE ALONG THE OLD FRONTAL BOUNDARY FROM TUESDAY...TO OFF THE CAROLINA COASTS BY LATE THURSDAY NIGHT. COULD BE INTERESTING WITH RESPECT TO FREEZING AND FROZEN PCPN IF ENUF COLD AIR GETS PULLED INTO THE SYSTEM. RIGHT NOW ITS AN ALL RAIN EVENT GIVEN LATEST THICKNESS SCHEMES ACROSS THE AREA. HAVE GONE WITH ANOTHER BRIEF REPRIEVE ON FRIDAY WITH CAA BEHIND THE DEPARTING LOW ACROSS THE AREA. SATURDAY WILL FEATURE ANOTHER CHANCE FOR PCPN. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... SOUTHERN STREAM VORT PULLING UP MOISTURE FROM THE GULF WELL AHEAD OF IT. VIA RUC AND WATER VAPOR...THE VORT IS ENTERING THE WESTERN GULF AT THE MOMENT. SFC LOW CONTINUES TO DEVELOP IN THE CENTRAL GULF AHEAD OF THE UPPER VORT. EXPECT OVERRUNING PCPN TO AFFECT THE AREA TERMINALS...COMMENCING WITH THE INLAND TERMINALS 1ST BY 13Z...THEN THE COASTAL ONES BY 15Z. IFR AND LIFR CONDITIONS WILL BECOME PREDOMINATE AFTER 15Z AND LAST ROUGHLY THRU 07Z SUNDAY. THE HEAVIEST RAIN WILL OCCUR BETWEEN 17Z AND 22Z SATURDAY WHERE MODERATE RAIN HAS BEEN TEMPO`D. OVERALL...WINDS WILL REMAIN N-NNE...360-030...THRUOUT THE DAY AT SPEEDS AROUND 10 KT. THEN BEGIN TO BACK THIS EVENING AND OVERNITE AS THE SFC LOW PASSES EAST OF THE AREA...ALLOWING SOME COLDER AIR TO WORK ITS WAY INTO THE AREA. THE INLAND TERMINALS WILL LIKELY OBSERVE IP AND SN MIXING WITH THE RAIN DURING THE EVENING AND OVERNIGHT...WITH PCPN POSSIBLY BECOMING ALL SNOW PRIOR TO ENDING ESPECIALLY ACROSS LBT. VFR CONDITIONS SUNDAY AND MONDAY. A WEAK SYSTEM WILL APPROACH THE AREA TUESDAY...WITH IFR CONDITIONS POSSIBLE TUESDAY NIGHT INTO WEDNESDAY MORNING. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 10 AM SATURDAY...WAVE HEIGHTS ARE INCREASING THIS MORNING AS THE NORTHERLY PRESSURE GRADIENT TIGHTENS. THE LOW IS MOVING INTO THE NE GULF OF MEXICO AND WILL QUICKLY MOVE NE OFF THE SE COAST THROUGH THE AFTERNOON AND EVENING. COLD AIR ADVECTION IN THE WAKE OF THE LOW WILL SUPPORT STRONGER OFFSHORE FLOW THROUGH THE EVENING. NO CHANGES NEEDED TO THE SMALL CRAFT ADVISORY. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...SUNDAY TO FEATURE ARCTIC AIR ADVECTING ACROSS THE COASTAL WATERS...WITH SPEEDS AROUND 25 KT AND GUSTS UP TO 30 KT. WOULD NOT BE SURPRISED TO C A FEW GUSTS UP TO 35 KT EARLIER IN THE DAY. HAVE OUTLINED A RANGE OF SEAS ACROSS THE WATERS DUE TO THE NW TO N OFFSHORE TRAJECTORY. SEAS AND WINDS WILL DROP BELOW SCA CONDITIONS DURING THE MID-AFTERNOON HOURS AS THE CENTER OF THE SFC HIGH APPROACHES FROM THE WEST CAUSING THE SFC TO RELAX SOME ACROSS THE IMMEDIATE COASTAL WATERS. MODELS HAVE INDICATED THE CENTER OF THE SFC HIGH PASSING OFF THE CENTRAL NC COAST MONDAY...AND WELL OFFSHORE MONDAY NIGHT. THIS WILL CAUSE WINDS TO VEER TO THE NE...WITH MODELS HAVING INDICATED THE DEVELOPMENT OF AN INVERTED SFC TROF OFF THE CAROLINA COASTS BY MON NITE. THE SFC PG TO BECOME TIGHTENED BY LATE MONDAY ESPECIALLY OVER THE SOUTHERN WATERS AND WILL RESULT IN WIND SPEEDS ATLEAST IN THE 15-20 KT RANGE...ESPECIALLY THE SOUTHERN WATERS. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 3 AM SATURDAY...TUESDAY WILL FEATURE THE BREAKDOWN OF THE WEDGE AND THE COASTAL TROF WITH NE WINDS BECOMING S OR SW AHEAD OF THE APPROACH OF A COLD FRONT. MODELS SEEM A BIT HIGH ON WAA WIND SPEEDS ACROSS THE COLDER SSTS OF THE ILM COASTAL WATERS AND WOULD LIKE TO LOWER THEM SOME. HAVE DONE THE SAME WITH SEAS WITH WINDS VEERING TO THE WEST LATER IN THE DAY WHICH WILL ALSO AID IN KNOCKING THEM DOWN. CFP SLATED FOR TUE NITE...ENDING THE THREAT FOR PCPN...WITH NW WINDS PICKING UP TO 15 TO 20 KT WITH RANGE OF SEAS EXPECTED ACROSS THE WATERS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SUNDAY FOR SCZ017-023-024. NC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SUNDAY FOR NCZ087-096. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 2 PM EST SUNDAY FOR AMZ250-252-254-256. && $$ SYNOPSIS...SRP NEAR TERM...SRP SHORT TERM...III/DCH LONG TERM...DCH AVIATION...DCH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 645 AM EST SAT JAN 19 2008 .SYNOPSIS... LOW PRESSURE IN THE WESTERN GULF OF MEXICO WILL MOVE OFF THE SOUTHEAST UNITED STATES COAST THIS MORNING. THE LOW WILL INTENSIFY AS IT MOVES RAPIDLY TO THE NORTHEAST ACROSS THE OFFSHORE WATERS OF THE CAROLINAS BY SATURDAY EVENING. ARCTIC HIGH PRESSURE WILL BUILD INTO THE CAROLINAS SUNDAY THROUGH MONDAY. A COASTAL TROUGH MAY DEVELOP OFFSHORE ON TUESDAY BEFORE BEING SWEPT AWAY BY A STRONG COLD FRONT TUESDAY NIGHT. HIGH PRESSURE TO BUILD IN FOR WEDNESDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM THIS MORNING...NO QUESTION...RAIN WILL OCCUR TODAY AND QPFS IN MOST ARE WILL BE ABOVE 1". BIGGEST FORECAST MYSTERY REMAINS HOW PRECIP ENDS OVERNIGHT. LATEST SOUNDINGS SHOW AN ENVIRONMENT THAT WOULD PROMOTE A SLEET/RAIN MIX THAT CHANGES OVER TO MOSTLY OR ALL SNOW AS IT ENDS. WHILE SOUNDINGS DROP BELOW FREEZING THROUGH ALL LAYERS...ESPECIALLY INLAND...THERE IS STILL SOME QUESTION AS TO IF/WHEN CHANGE TO FROZEN WILL OCCUR. TEMPS THROUGH THE LAYER DO NOT DROP MUCH BELOW FREEZING SO SLEET COULD END UP BEING MORE PREVALENT THAN SNOW. GFS IS SHOWING STRONG FRONTOGENESIS OVER INLAND ILM COUNTIES WHICH COULD RESULT IN SOME BANDING OF PRECIP. HAVE DECIDED TO RAISE A WINTER WX ADVISORY FOR INLAND MOST COUNTIES...BUT WILL STOP SHORT OF GOING WITH A WARNING(2"). SEVERAL FACTORS SHOULD HELP KEEP SNOW/SLEET AMOUNTS UNDER 2" FOR THIS EVENT. FIRST...GROUND TEMPS...AS WELL AS THE BOUNDARY LAYER...REMAIN ABOVE FREEING THROUGH THE EVENT. ANOTHER MITIGATING FACTOR IS THE FACT THAT SNOW THAT DOES FALL WILL BE EXTREMELY WET AND HEAVY AND LESS LIKELY TO ACCUMULATE TO WARNING CRITERIA. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM THIS MORNING...ARCTIC AIR MASS BUILDS IN SUN AS SFC CYCLONE MOVING AWAY FROM THE REGION DEEPENS AND DEEP UPPER TROF SWINGS THROUGH. 1000-500 THICKNESS VALUES DROP INTO THE 520S AND 850 TEMPS DROP BELOW -10. UPPER PATTERN QUICKLY BECOMES ZONAL WITH SFC HIGH MOVING OFFSHORE LATE SUN INTO MON AND RETURN FLOW STARTING MON NIGHT. TEMPERATURES WILL REMAIN WELL BELOW CLIMO...STRUGGLING TO REACH 40 ON SUN AND FALLING INTO THE TEENS/LOW 20S SUN NIGHT. SLIGHT WARM UP ON MON...WITH TEMPS BARELY HITTING 40...THOUGH PARTIAL THICKNESS VALUES SUGGEST TEMPS MAY NOT MAKE IT TO 40 IN MANY AREAS. TEMPS START TO REBOUND MON NIGHT AS SRLY FLOW STARTS TO DEVELOP AND COASTAL TROF BEGINS TAKING SHAPE. INCREASING CLOUD COVER MON NIGHT WILL HELP KEEP TEMPS CLOSE TO CLIMO. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM FRIDAY...WEAK WARM AIR ADVECTION ON TUESDAY AHEAD OF A COLD FRONT SHOULD BRING TEMPS TO OR SLITELY ABOVE NORMAL. THAT MAY BECOME THE WARMEST DAY OF THE EXTENDED PERIOD WITH THE MAJORITY OF THE LONG TERM FEATURING TEMPS BELOW NORMAL WITH THE LATEST MEX MOS GUIDANCE HOT OFF THE PRESS ILLUSTRATING THIS. VERY ACTIVE WEEK AND PROGRESSIVE PATTERN CONTINUES. GFS MODEL SEEMS OVERZEALOUS WITH MOISTURE WITH THE COLD FRONT ON TUESDAY AND AS A RESULT WILL STAY ON THE LOW CHANCE SIDE FOR PRECIP. BRIEF REPRIEVE ON WEDNESDAY B4 NEXT PCPN EVENT. WED NITE INTO THU NIGHT FEATURES AN OVERRUNING TYPE EVENT WITH LOW PRESSURE FROM THE GULF MOVING NE ALONG THE OLD FRONTAL BOUNDARY FROM TUESDAY...TO OFF THE CAROLINA COASTS BY LATE THURSDAY NIGHT. COULD BE INTERESTING WITH RESPECT TO FREEZING AND FROZEN PCPN IF ENUF COLD AIR GETS PULLED INTO THE SYSTEM. RIGHT NOW ITS AN ALL RAIN EVENT GIVEN LATEST THICKNESS SCHEMES ACROSS THE AREA. HAVE GONE WITH ANOTHER BRIEF REPRIEVE ON FRIDAY WITH CAA BEHIND THE DEPARTING LOW ACROSS THE AREA. SATURDAY WILL FEATURE ANOTHER CHANCE FOR PCPN. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... SOUTHERN STREAM VORT PULLING UP MOISTURE FROM THE GULF WELL AHEAD OF IT. VIA RUC AND WATER VAPOR...THE VORT IS ENTERING THE WESTERN GULF AT THE MOMENT. SFC LOW CONTINUES TO DEVELOP IN THE CENTRAL GULF AHEAD OF THE UPPER VORT. EXPECT OVERRUNING PCPN TO AFFECT THE AREA TERMINALS...COMMENCING WITH THE INLAND TERMINALS 1ST BY 13Z...THEN THE COASTAL ONES BY 15Z. IFR AND LIFR CONDITIONS WILL BECOME PREDOMINATE AFTER 15Z AND LAST ROUGHLY THRU 07Z SUNDAY. THE HEAVIEST RAIN WILL OCCUR BETWEEN 17Z AND 22Z SATURDAY WHERE MODERATE RAIN HAS BEEN TEMPO`D. OVERALL...WINDS WILL REMAIN N-NNE...360-030...THRUOUT THE DAY AT SPEEDS AROUND 10 KT. THEN BEGIN TO BACK THIS EVENING AND OVERNITE AS THE SFC LOW PASSES EAST OF THE AREA...ALLOWING SOME COLDER AIR TO WORK ITS WAY INTO THE AREA. THE INLAND TERMINAS WILL LIKELY OBSERVE IP AND SN MIXING WITH THE RAIN DURING THE EVENING AND OVERNIGHT...WITH PCPN POSSIBLY BECOMING ALL SNOW PRIOR TO ENDING ESPECIALLY ACROSS LBT. VFR CONDITIONS SUNDAY AND MONDAY. A WEAK SYSTEM WILL APPROACH THE AREA TUESDAY...WITH IFR CONDITIONS POSSIBLE TUESDAY NIGHT INTO WEDNESDAY MORNING. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 3 AM THIS MORNING...NRLY FLOW TODAY WILL BEGIN INCREASING AS LOW PRESSURE IN THE NRN GOMEX CROSSES FL AND MOVES UP THE E COAST. GRADIENT WILL TIGHTEN AS LOW DEEPENS...WITH SPEEDS LIKELY EXCEEDING 25 KT LATE TONIGHT. GOING WITH SCA FOR ALL ZONES STARTING TONIGHT AND LASTING THROUGH THE PERIOD. OFFSHORE COMPONENT OF WINDS WILL KEEP SEAS WITHIN 20 NM AT OR BELOW 6 FT. STRONG COLD ADVECTION IN THE WAKE OF THE SYSTEM MAY ADD A LITTLE TO SFC WINDS...BUT COOLER SHELF WATERS WILL PREVENT STRONGEST WINDS FROM MIXING TO THE SURFACE. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... SUNDAY TO FEATURE ARCTIC AIR ADVECTING ACROSS THE COASTAL WATERS...WITH SPEEDS AROUND 25 KT AND GUSTS UP TO 30 KT. WOULD NOT BE SURPISED TO C A FEW GUSTS UP TO 35 KT EARLIER IN THE DAY. HAVE OUTLINED A RANGE OF SEAS ACROSS THE WATERS DUE TO THE NW TO N OFFSHORE TRAJECTORY. SEAS AND WINDS WILL DROP BELOW SCA CONDITIONS DURING THE MID-AFTERNOON HOURS AS THE CENTER OF THE SFC HIGH APPROACHES FROM THE WEST CAUSING THE SFC TO RELAX SOME ACROSS THE IMMEDIATE COASTAL WATERS. MODELS HAVE INDICATED THE CENTER OF THE SFC HIGH PASSING OFF THE CENTRAL NC COAST MONDAY...AND WELL OFFSHORE MONDAY NIGHT. THIS WILL CAUSE WINDS TO VEER TO THE NE...WITH MODELS HAVING INDICATED THE DEVELOPMENT OF AN INVERTED SFC TROF OFF THE CAROLINA COASTS BY MON NITE. THE SFC PG TO BECOME TIGHTENED BY LATE MONDAY ESPECIALLY OVER THE SOUTHERN WATERS AND WILL RESULT IN WIND SPEEDS ATLEAST IN THE 15-20 KT RANGE...ESPECIALLY THE SOUTHERN WATERS. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 3AM SATURDAY...TUESDAY WILL FEATURE THE BREAKDOWN OF THE WEDGE AND THE COASTAL TROF WITH NE WINDS BECOMING S OR SW AHEAD OF THE APPROACH OF A COLD FRONT. MODELS SEEM A BIT HIGH ON WAA WIND SPEEDS ACROSS THE COLDER SSTS OF THE ILM COASTAL WATERS AND WOULD LIKE TO LOWER THEM SOME. HAVE DONE THE SAME WITH SEAS WITH WINDS VEERING TO THE WEST LATER IN THE DAY WHICH WILL ALSO AID IN KNOCKING THEM DOWN. CFP SLATED FOR TUE NITE...ENDING THE THREAT FOR PCPN...WITH NW WINDS PICKING UP TO 15 TO 20 KT WITH RANGE OF SEAS EXPECTED ACROSS THE WATERS. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SUNDAY FOR SCZ017-023-024. NC...WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EST SUNDAY FOR NCZ087-096. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 2 PM EST SUNDAY FOR AMZ254-256. SMALL CRAFT ADVISORY FROM 1 AM TO 2 PM EST SUNDAY FOR AMZ250- 252. && $$ SYNOPSIS...REK/DCH NEAR TERM...III SHORT TERM...III/DCH LONG TERM...DCH AVIATION...DCH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 840 PM CST SUN JAN 20 2008 .DISCUSSION... FORECAST CHALLENGE FOR UPDATE WILL BE CLOUD TRENDS AND TEMPERATURES. MID LEVEL SHEAR AXIS FROM HUDSON BAY SE TO CENTRAL ROCKIES CONTINUES TO SAG SOUTHWARD PUTTING FA IN GENERAL MID LEVEL WESTERLY FLOW. MID AND UPPER LEVEL CLOUDS CONTINUE TO PUSH EASTWARD ACROSS FA AHEAD OF CENTRAL/NORTHERN ROCKIES SYSTEM. AREAS EAST OF VALLEY REGION HAVE BEEN LAST TO SEE CLOUDS AND CURRENT TEMPERATURES RUNNING CLOSE TO THIS TIME YSTDY. FARTHER WEST CLOUDS HAVE PUT A DAMPER ON COOLING. WITH CIGS CLEAR BACK INTO MT CLOUDS LIKELY TO IMPACT REGION MOST OF NIGHT. EASTERN AREAS SHOULD EVENTUALLY GET INTO CLOUDS WHICH SHOULD LIMIT ADDITIONAL DROP. SOME CLEARING OVER NW ND AND RUC DOES SHOW SOME DRYING THIS AREA LATER TONIGHT SO DVL BASIN MAY BE ABLE TO DROP MORE LATE TONIGHT. WILL MAKE SOME ADJUSTMENTS TO TEMPERATURE OVER AREAS EXPECTED TO BE IN CLOUDS MOST OF NIGHT MAINLY VALLEY WEST SOUTH OF HIGHWAY 2. WILL IN TURN INCREASE CLOUDS IN GRIDS OTHERWISE MINIMAL ADDITIONAL CHANGES PLANNED. && .AVIATION...VFR MID LEVEL CIGS WILL CONTINUE TO ADVANCE ACROSS FA. AT THIS POINT LOOKING AT UPSTREAM CIGS NOT ANTICIPATING ANY CIGS BLO 4K FT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 1030 AM CST SUN JAN 20 2008 .DISCUSSION... ECMWF WAS FASTER THAN THE NAM AND THE GFS. THE GFS WAS THE SLOWEST OF THE THREE MODELS AT 84 HOURS. GFS AND RUC HANDLED THE CURRENT LOW LEVEL WIND FIELDS BEST FROM THE VAD WINDS. NAM AND GFS WERE A BIT WARM AT 925 HPA COMPARED TO TAMDAR SOUNDINGS. MODELS DID A BETTER JOB AT 850 HPA WITH THE SLIGHTLY COOLER GFS CLOSER TO OBSERVED. WILL USE THE GFS. FOG LOOP/SURFACE OBS SHOW CLOUD DECK AROUND 9 THOUSAND FEET HAS ENTERED WESTERN ZONES. CLOUD DECK EXTENDED INTO SOUTHERN SK. DECK WAS MOVING TO THE SOUTHEAST BUT APPEARS TO BE DISSIPATING ON THE EASTERN EDGE. POCKET OF MOISTURE AT 700 HPA ON GFS APPEARS TO BE HANDLED WELL. TEMPERATURES HAVE NOT RECOVERED MUCH UNDER CLOUD DECK. BOTH RUC AND GFS HAS BEST SUBSIDENCE OVER THE VALLEY AND MAY DISSIPATING EAST EDGE OF CLOUD DECK. WILL CHECK ZONES. && .PREVIOUS DISCUSSION /ISSUED 346 AM SUN JAN 20 2008/... KEY CHALLENGE FOR TONIGHT WILL BE CLOUD COVER AND IMPACTS ON TEMPERATURES IN THE DEVILS LAKE BASIN AND FAR WESTERN PORTION OF THE FA. MID AND HIGH CLOUDS SLOWLY DRIFTING EASTWARD INTO EASTERN ND. TEMPS HAD ALREADY PLUMMETED INTO THE NEG 20S BEFORE CLOUD DECK MOVED IN...SO DO NOT SEE MUCH IMPACT ON TEMPS. HIGH PRESSURE WILL CONTINUE TO DOMINATE WX PATTERN SUNDAY AND MONDAY... WITH ARCTIC AIRMASS REMAINING IN PLACE AND KEEPING DAYTIME HIGHS BELOW ZERO FOR ALL BUT THE SOUTHERN EDGE OF THE FA. WINDS WILL BE LESS THAN 10 MPH...SO WIND CHILL ADVISORY WILL NOT BE REQUIRED. NEXT CHALLENGE WILL BE TIMING OF CLIPPER MOVING THROUGH TUE AFTERNOON AND NIGHT. GFS MUCH QUICKER WITH SYSTEM THAN THE NAM...AND HAS SPED UP TIMING OF LOW OVER LAST TWO RUNS. TENDING TOWARD FASTER GFS SOLUTION...BUT NOT AS AGGRESSIVE ON TIMING OF PRECIP IN THE 12Z TO 18Z TUE TIME FRAME. DID INTRODUCE A CHANCE FOR TUE AFTERNOON AND UPPED TUE NIGHT TO CHANCE POPS. OVERALL NOT A TREMENDOUS AMOUNT OF MOISTURE WITH SYSTEM AND ATTM LOOKING FOR NO MORE THAN A HALF INCH SNOW ACCUMULATION. LITTLE CHANGES MADE TO FORECAST BEYOND DAY FOUR. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ HOPPES nd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1115 AM CST SUN JAN 20 2008 .DISCUSSION... SNOW BAND SO FAR REMAINING JUST SOUTH OF OUR CWA BORDER...AND APPEARS TO HAVE SET UP NEAREST BAND OF 850-800MB FRONTOGENESIS BASED ON RUC13. SOME MID LEVEL DEVELOPMENT TRYING TO NUDGE NORTH WITH 800-750MB FRONTOGENESIS AREA...THOUGH THIS AREA WILL HAVE TO FIGHT QUITE A DEEP LAYER OF DRY AIR AS IT CONTINUES TO PROGRESS NORTHEAST THROUGH THE AFTERNOON. FOR TODAY...HAVE SLOWED DEVELOPMENT INTO FAR SOUTHERN AREAS OF THE CWA...AND SCALED BACK POPS ALONG THE NORTHEAST EDGE OF THE PRECIP AREA BASED ON SIMILAR EVOLUTION TO RH LEVELS BELOW 800MB ON BOTH RUC AND NAM MODELS. THIS KEEPS EVEN SLIGHT CHC POPS ROUGHLY SOUTHWEST OF A KHON-KFSD-KSPW LINE THROUGH 00Z. WITH FRONTAL BOUNDARY ACTING AS PRIMARY FORCING MECHANISM FOR SNOW AND INFLUX OF DRY LOW LEVEL AIR FROM THE SURFACE HIGH MOVING THROUGH NORTHERN MINNESOTA...EXPECT A FAIRLY SHARP CUTOFF ALONG NORTHERN EDGE OF SNOW. STILL HAVE TO EVALUATE NEW MODELS IN MORE DETAIL BEFORE MAKING SIGNIFICANT CHANGES TO OVERNIGHT/EARLY MONDAY. HOWEVER AT FIRST GLANCE LOOKS LIKE NAM TRIES TO EXPAND SOME HEAVIER PRECIP TOO FAR NORTH OF AFOREMENTIONED KEY FRONTAL LAYER BETWEEN 850-750MB. BOTH NAM AND RUC...AND TO SOME DEGREE GFS /THOUGH HARDER TO DISCERN AT COARSER RESOLUTION/ SHOW A WEAK OFFSHOOT OF FRONTOGENESIS LIFT NORTHEAST AHEAD OF THE MAIN BAND DURING THE LATE AFTERNOON/EVENING. DO NOT THINK THIS WILL BE ABLE TO OVERCOME THE DRY AIR BY ITSELF... BUT COULD AID TOP-DOWN SATURATION ENOUGH FOR MAIN FRONTAL BOUNDARY WOULD BE ABLE TO PRODUCE SOME LIGHT PRECIP INTO THE FAR NORTH LATER TONIGHT. FOR NOW...BASED ON QUICK LOOK AT GFS AND NAM...WILL LET ADVISORY AREA RIDE AS IS...BUT MAY HAVE TO REFINE A LITTLE MORE THIS AFTERNOON AFTER BETTER LOOK AT LATEST MODELS/PRECIP EVOLUTION. UPDATED GRIDS/PFM/ZFP HAVE BEEN SENT. && .AVIATION... CONDITIONS WL GRADUALLY ERODE FM VFR ACROSS KSUX THIS AFTERNOON. IT IS ANTICIPATED THAT KSUX WL STAY VFR THRU THE MORNING HRS...WITH ALTOCUMULUS CLOUDS IN THE 6K TO 10K FEET AGL LYR. BUT THEN AS THE LOWER ATMOSPHERE SATURATES...SNOW WL LIKELY BEGIN TO FALL AT KSUX AS THE AFTERNOON PROGRESSES...DROPPING CIGS DOWN INTO THE MVFR CAT WITH SOME IFR VIS. DRIER LOW LEVELS PREVAIL AT KFSD AND KHON THRU THE DAY...AND THESE TWO SITES SHOULD STAY VFR THRU 00Z THIS EVENING... WITH WORSENING CONDITIONS AFTER THAT. && .PREV DISCUSSION... STILL ON TRACK FOR A LONG DURATION SNOW EVENT ACROSS A GOOD PORTION OF OUR CWA THROUGH MONDAY EVENING. CURRENT RADAR SHOWING ECHOES OVER WESTERN SOUTH DAKOTA INTO NORTHERN AND EASTERN NEBRASKA...THOUGH LITTLE IS REACHING THE GROUND WITH LOW LEVEL DRY AIR IN PLACE OVER THE REGION. THE MOST SIGNIFICANT CHANGE FROM PREVIOUS FORECAST IS THAT MODELS ARE NOW TRENDING FARTHER TO THE NORTH WITH FORCING AND MOISTURE WITH THE SYSTEM. WHAT THIS MEANS FOR US IS THAT MORE OF OUR CWA WILL BE AFFECTED THAN PREVIOUSLY THOUGHT. NICE OVERRUNNING SITUATION EXPECTED TO DEVELOP OVER THE REGION LATER THIS MORNING AS LOW TO MID LEVEL WINDS BEGIN TO ADVECT MOISTURE FROM THE SOUTH...OVER THE VERY COLD AIR SITUATED OVER THE NORTHERN PLAINS. STRONG ISENTROPIC LIFT WILL INCREASE OVER THE SOUTHERN PORTIONS OF THE CWA THROUGHOUT THE DAY...WHILE 750 MB FRONTOGENESIS WILL DEVELOP OVER OUR SOUTHWEST IN THE MORNING...THEN SLOWLY PIVOT ACROSS OUR SOUTH DURING THE AFTERNOON. WILL SEE LITTLE IN THE WAY OF PRECIPITATION OVER THE NORTHEASTERN HALF OF THE FA TODAY...WITH THE DRY LOW LEVEL AIR HOLDING STRONG. BULK OF THE PRECIPITATION WILL OCCUR TONIGHT INTO TOMORROW MORNING AS MID LEVEL FRONTOGENESIS/ISENTROPIC LIFT INCREASES...ESPECIALLY OVER OUR SOUTH AND SOUTHEASTERN QUADRANT OF THE CWA. WITH MID LEVEL TEMPERATURES HOVERING BETWEEN -15 TO -20 C OVER THE REGION...SNOW WILL BE VERY EFFICIENT...AND WILL LIKELY SEE IN EXCESS OF A 20 TO 1 LIQUID/SNOW RATIO. PRECIPITATION WILL END FROM NORTHWEST TO SOUTHEAST ON MONDAY AFTERNOON AS MID AND LOW LEVEL WINDS TURN FROM THE NORTHWEST...USHERING IN MUCH DRIER AIR POSITIONED JUST TO THE NORTH OF US. WILL HAVE LITTLE DIURNAL RANGE WITH RESPECT TO TEMPERATURES FOR TONIGHT INTO TOMORROW WITH CLOUD COVER AND PRECIPITATION. IN TERMS OF HEADLINES...KEPT PREVIOUS SNOW ADVISORIES GOING...THOUGH ADDED ADDITIONAL ADVISORIES NORTHWARD TO THE I 90 CORRIDOR. TOTAL SNOWFALL AMOUNTS LOOK TO RANGE FROM 2 TO 3 INCHES ALONG THE I 90 CORRIDOR...TO 6 TO 8 INCHES OVER THE SOUTHERN PORTIONS OF OUR NORTHWESTERN IOWA AND NEBRASKA ZONES. ELECTED TO KEEP A SNOW ADVISORY...VERSUS A HEAVY SNOW WARNING...IN THESE SOUTHERN AREAS BECAUSE OF THE LONG DURATION OF THE EVENT. FOR THE REMAINDER OF THE SHORT TERM...DRYING OUT ON TUESDAY...THEN ANOTHER SHOT OF REINFORCING COLD AIR ON WEDNESDAY WITH PASSAGE OF A SHORTWAVE. COULD SEE A LITTLE LIGHT SNOW WITH THIS FEATURE...THOUGH KEPT LOW POPS AT THIS TIME. && .FSD WATCHES/WARNINGS/ADVISORIES... IA...SNOW ADVISORY FROM NOON TODAY TO 6 PM CST MONDAY FOR IAZ020>022- 031-032. SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST MONDAY FOR IAZ001>003-012>014. MN...NONE. NE...SNOW ADVISORY FROM NOON TODAY TO 6 PM CST MONDAY FOR NEZ013-014. SD...SNOW ADVISORY FROM NOON TODAY TO 6 PM CST MONDAY FOR SDZ070-071. SNOW ADVISORY FROM NOON TODAY TO 12 PM CST MONDAY FOR SDZ050-063- 068-069. SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 PM CST MONDAY FOR SDZ067. SNOW ADVISORY FROM 6 PM THIS EVENING TO 12 PM CST MONDAY FOR SDZ064>066. && $$ JH sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 935 AM EST SAT JAN 19 2008 .DISCUSSION...14Z SURFACE ANALYSIS WOULD SUPPORT THE ARCTIC COLD FRONT FROM A TUP (TUPELO MS) TO BNA (NASHVILLE) TO NEAR LEX (LEXINGTON KY) LINE. HOWEVER...WHAT WILL HURT OUR PRECIPITATION (PCPN) CHANCES IS THE FACT THAT DEW POINT TEMPS ARE QUITE LOW ON EITHER SIDE OF THE ARCTIC FRONT THIS MORNING (TEENS TO 20S). MAIN AREA OF PCPN CONTINUES TO BE TO OUR SE THIS MORNING WITH HEAVIER PCPN INDICATED FROM CENTRAL GA TO SC...WHERE MOISTURE AND BEST LIFT (MAINLY ISENTROPIC) IS OCCURRING. WESTERN EDGE OF THE PCPN SHIELD COULD CLIP THE ERN MTN AREAS WHERE SNOW ADVISORIES RUN TIL 4PM EST...AS ADVERTISED BY LATEST RUC AND GFS MODELS. WEAK FORCING IS INDICATED INTO THE AFTERNOON HOURS...ALTHO AIRMASS OUTSIDE OF THE ERN MTNS WILL BE DIFFICULT TO SATURATE GIVEN CURRENT MID TO HIGH CLOUD DECK AND SUCH LOW DEW POINT TEMPS. SURFACE TEMPS WILL ALSO HINDER ANY SNOW ACCUMULATIONS. THUS...WILL LET SNOW ADVISORIES CONTINUE BUT WILL LOWER AMOUNTS FOR NRN MTNS OF E TN...WITH NO THREAT OF ANY SNOW ACCUMULATIONS WEST OF THE MTNS. BEST CHANCES OF SNOW STILL APPEAR TO BE OVER CHEROKEE AND CLAY COUNTIES...BUT SURFACE TEMPS THERE MAY BE TOO WARM FOR SNOW TO ACCUMULATE. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 39 18 38 17 48 / 50 20 0 0 10 KNOXVILLE MCGHEE TYSON AIRPORT, TN 38 14 32 14 38 / 50 20 0 0 10 OAK RIDGE, TN 38 14 31 13 43 / 50 20 0 0 10 TRI CITIES AIRPORT, TN 36 12 27 7 40 / 50 20 0 0 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: CHEROKEE...CLAY. TN...SNOW ADVISORY FROM 6 AM THIS MORNING TO 4 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: JOHNSON...SOUTHEAST CARTER... SOUTHEAST GREENE...UNICOI. SNOW ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR THE FOLLOWING ZONES: BLOUNT SMOKY MOUNTAINS...COCKE SMOKY MOUNTAINS... EAST POLK...SEVIER SMOKY MOUNTAINS...SOUTHEAST MONROE. VA...NONE. && $$ TG tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BROWNSVILLE TX 318 AM CST SAT JAN 19 2008 .DISCUSSION... MIDLEVEL TROUGH/VORT HAVE PRETTY MUCH CLEARED THE AREA...WITH RAIN ACTIVITY CEASING AND MOVING TO THE NORTHEAST. CLOUD COVER BEGINNING TO FADE AS WELL..WITH BREAKS NOTED IN LOW OVERCAST IN LOCAL ASOS OBS. LATEST RUC RUN HAS THE CLOUD COVER OUT OF THE WESTERN ZONES BY DAWN...WITH CLEARING ALONG THE COAST BY NOON. ADVANCING DOME OF SFC HIGH PRESSURE BEING PULLED SOUTHWARD THROUGH TEXAS WILL BRING ANOTHER NIGHT OF COLD TEMPS...WITH LOWS IN THE LOW 40S CAMERON COUNTY TO NEAR FREEZING IN NORTHERN JIM HOGG AND BROOKS COUNTIES. THE SFC HIGH MOVES EAST OVER THE WEEKEND...WITH ONSHORE FLOW REDEVELOPING LATE SUNDAY. THIS WILL BRING BACK THE CHANCE FOR RAIN DUE TO MORE OVERRUNNING LIKE YESTERDAY. UPPER LEVEL WINDS DURING MOST OF THE NEXT WEEK WILL CONTINUE TO BE FROM THE SOUTHWEST. THIS WILL KEEP COLD FRONT FROM ADVANCING INTO THE GULF. THE NEXT FRONT IS EXPECTED LATER TUESDAY...AND MAY STALL THROUGH THE CWA OR TRANSITION INTO ANOTHER COASTAL TROUGH DURING THE MIDDLE OF NEXT WEEK. THIS WILL LEAD TO ANOTHER ROUND OF LIGHT RAIN SHOWERS...ESPECIALLY NEAR THE FRONTAL ZONE. LACK OF COLD AIR BEHIND FRONTS WILL ALLOW TEMPS TO RECOVER BACK TO NEAR NORMAL NEXT WEEK...WITH SOME SLIGHTLY ABOVE NORMAL READINGS POSSIBLE TUESDAY AND WEDNESDAY. && .AVIATION... LOW PRESSURE IS EXITING THE REGION WITH DRIER AIR ALOFT ADVANCING NORTHEAST. MVFR TO OCCASIONAL IFR CIGS ARE EXPECTED THROUGH MID MORNING THEN THE OVERCAST SKIES SHOULD RAPIDLY BREAK BY MID MORNING AND CONTINUE TO CLEAR SW TO NE THE REST OF THE DAY. CLEAR SKIES TONIGHT INTO EARLY SUNDAY WITH SOME POSSIBLE PATCHY GROUND FOG DEVELOPING. CLOUDS INCREASE ONCE AGAIN SUNDAY WITH CIGS POSSIBLY LOWERING TO MVFR LATE. && .MARINE... AT 2 AM BUOY 42020 INDICATED SEAS AT 12.5 FEET WITH AN 8 SECOND PERIOD AND WINDS FROM THE NORTHWEST AT 30 KNOTS WITH GUSTS AROUND 35 KNOTS. STRONG NORTH TO NORTHWEST WINDS AND HIGH SEAS WILL PERSIST MUCH OF TODAY AS THE TIGHT PRESSURE GRADIENT BETWEEN A DEPARTING LOW PRESSURE AREA OVER THE WESTERN GULF AND BUILDING HIGH PRESSURE OVER NORTH TEXAS IS MAINTAINED. WINDS AND SEAS SLOWLY RELAX TONIGHT INTO SUNDAY AS THE HIGH PRESSURE RIDGE BECOMES THE DOMINATE WEATHER FEATURE. SMALL CRAFT ADVISORIES WILL CONTINUE FOR ALL MARINE AREAS THROUGH THE MORNING WITH FLAGS LOWERED FOR THE LAGUNA THIS AFTERNOON AS WINDS ARE EXPECTED TO DROP BELOW 20 KNOTS SUSTAINED. WINDS OFFSHORE MAY LOWER BELOW SMALL CRAFT CRITERIA HOWEVER SEAS MAY BE SLOW IN SUBSIDING THUS SMALL CRAFT ADVISORIES ARE EXTENDED INTO SUNDAY MORNING. AN EASTERLY SWELL SETS UP LATER SUNDAY INTO THE FIRST HALF OF NEXT WEEK AS WINDS VEER EAST TO SOUTHEAST AS HIGH PRESSURE SETTLES OVER THE SOUTHEAST U.S. TWO COLD FRONTS MOVE INTO THE NORTHERN GULF...ONE TUESDAY AND ANOTHER THURSDAY...BUT CONFIDENCE IS LOW ON HOW FAR SOUTH THEY PUSH BEFORE THEY STALL. OVERALL...MARINE CONDITIONS COULD REMAIN ROUGH THROUGH MUCH OF THE COMING WEEK. && .PRELIMINARY POINT TEMPS/POPS... BAYVIEW/PORT ISABEL 57 44 67 61 / 0 0 10 20 BROWNSVILLE 57 43 68 60 / 0 0 10 20 HARLINGEN 58 41 66 59 / 0 0 10 20 MCALLEN 59 42 66 57 / 0 0 10 20 RIO GRANDE CITY 58 38 64 56 / 0 0 10 10 SOUTH PADRE ISLAND 57 46 67 62 / 0 0 10 20 && .BRO WATCHES/WARNINGS/ADVISORIES... TX...HIGH SURF ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR TXZ251-256- 257. GM...SMALL CRAFT ADVISORY UNTIL NOON CST TODAY FOR GMZ130-132-135. SMALL CRAFT ADVISORY UNTIL 6 AM CST SUNDAY FOR GMZ150-155-170- 175. && $$ THIS PRODUCT IS ALSO AVAILABLE ON THE WEB AT: HTTP://WWW.WEATHER.GOV/BROWNSVILLE 64/59 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 319 PM CST SUN JAN 20 2008 .SHORT TERM...THROUGH WEDNESDAY NIGHT ENTIRE TIME FOCUSED ON INCOMING SNOW EVENT WHICH WILL HAVE TRAVEL IMPACTS...PERHAPS SIGNIFICANT IN SOME AREAS. ANCILLARY CONCERNS WERE EARLY EVENING TEMP PLUNGE TONIGHT...AND WINDS/COLD ON TUES AND WEDNESDAY. CURRENTLY...ARCTIC AIRMASS REMAINS ENTRENCHED WITH AXIS OF 1035+MB HIGH PRESSURE FROM ERN ND ALL THE WAY INTO DEEP SOUTH. TEMPERATURES TODAY ABOUT 5F WARMER THAN YDAY. THICK VEIL OF MID/HIGH LEVEL CLOUDS ALREADY ESTABLISHED ON BACKSIDE OF POOL OF ARCTIC AIR WHERE STRONG LOW/MID LEVEL BAROCLINIC ZONE IN PLACE. INTENSE UPPER LOW /PER GOES WATER VAPOR/ DIGGING DOWN WEST COAST OF WA/OR AND HEIGHTS PER 20.18Z RUC HAVE REALLY RISEN LAST 12HRS OVER THE CNTL CONUS IN DOWNSTREAM RIDGING FROM THIS FEATURE. BACKSIDE OF THE SFC/LOW LEVEL RIDGE AXIS FEATURES A SLY LOW LEVEL JET OVER 45KTS ALREADY IN SRN PLAINS...FURTHER TIGHTENING THE MID LEVEL BAROCLINIC ZONE AS THE FLOW BACKS IN RESPONSE TO WRN CONUS/CNTL CANADA POSITIVE TILT TROUGH AXIS. WATER VAPOR SHOWING ENERGY OVER WY/ID SHEARING OUT OF THE WRN TROUGH...AND MSAS SHOWS WEAK LEE CYCLOGENESIS IN ERN COLORADO IN RESPONSE. BROAD/MODEST UPPER TROPOSPHERIC JET IN PLACE OVER LOCAL AREA /110KT/ BETWEEN DEPARTING PORTION OF POLAR VORTEX AND RISING CNTL CONUS HEIGHTS. RADAR MOSAICS OVER NEB/SD SHOW BAND OF MODERATE SNOW /VSBYS LESS THAN 1SM/ ALREADY ESTABLISHED FROM WRN SD INTO ERN NEB...AND LIGHTER INTO MUCH OF WRN IA...WHERE DEFORMATION/CONVERGENCE ALREADY STRONG. THESE FEATURES ALL IN PLAY ON UPCOMING SNOW FORECAST. SNOW EVENT...HIGH CONFIDENCE IN IMPACTING SNOW EVENT BEGINNING LATER TONIGHT OVER NERN IA...EXPANDING AND INTENSIFYING MONDAY OVER MUCH OF FORECAST AREA...DIMINISHING FROM WEST TO EAST MONDAY EVENING. WITH NRN FRINGE OF SNOW BAND IN OUR FORECAST AREA...THERE ARE SOME SIGNIFICANT CHALLENGES...NOT TO MENTION GENERAL LATITUDE OF HEAVIER SNOW ACCUMS. LATEST NAM-WRF RUNS CONTINUE TO BE ON THE NRN-MOST EDGE OF THE GUIDANCE ENVELOPE...WITH FOCUSING NEAR- WARNING TYPE SNOW BAND FROM RST/LSE THROUGH MAUSTON/BLACK RIVER FALLS. THIS VERY EASILY TRACED TO A FURTHER NORTH TRACK OF ASSOCIATED PV ANOMALY ON 1.5 PV SFC /CURRENT ENERGY IN IDAHO/ ACROSS NRN IA AND SRN WISCONSIN...WITH SFC REFLECTION OF THE WAVE TO DEVELOP OVER SERN IA MOVING TO MILWAUKEE BY 12Z TUESDAY. REST OF NON-ENSEMBLE DATASETS ARE A TAD WEAKER...AND FURTHER SOUTH...WITH SFC LOW DEVELOPMENT THROUGH NRN IL INTO LOWER MICH AS THE UPPER PV SHIFTS THROUGH SRN IA/NRN MO. THIS HAS BIG IMPLICATIONS ON THE NRN FRINGE OF THE SNOW BAND...BUT HAS LITTLE IMPLICATION FOR SAY...NORTHEAST IOWA...WHERE TRACK DOESN/T MATTER SO MUCH...IT WILL SNOW AND ACCUMULATE THERE REGARDLESS. FROM A FORCING STANDPOINT...I HAVE NO BEEF BETWEEN THE LATEST 20.12Z NAM-WRF OR GFS. BOTH SHOW ANOMALOUS LOW LEVEL FLOW /SRN PLAINS 850MB FLOW 3 TO 5 SIGMA ABOVE CLIMO/ WITH STRONG TO VERY STRONG WARM ADVECTION SIGNAL AND ISENTROPIC ASCENT /275-285K LAYER/. MOISTURE REALLY STARTS TO WORK INTO THE SYSTEM DURING DAY ON MONDAY WITH SPEC HUMIDITIES OF 3-4 G/KG INTO NRN MO/SRN IA ON 280K SFC...AS 850MB MOISTURE FLUX IS A WELL-AGREED UPON 4 SIGMA ABOVE CLIMO BETWEEN WRF/GFS FROM THE GULF COAST INTO MO. NOT QUITE ALL THE WAY UP HERE...BUT MOISTURE WILL CERTAINLY BE INCREASING AND BROUGHT TO SATURATION ISENTROPICALLY AS THE SYSTEM ORGANIZES MORE ON MON. BOTH MODELS ALSO WELL AGREED IN 135KT UPPER JETLET OVER GREAT LAKES MOVING ONLY VERY SLOWLY EAST KEEPING BROAD SCALE SUPPORT FOR ASCENT OVER THE MN/WI/IA AREA. AS EXPECTED...SLOPED FRONTOGENETICAL AXIS IN PLACE AND RELATIVELY SLOW MOVING FROM LATE TONIGHT INTO MONDAY EVENING OVER FORECAST AREA. PATTERN NOT OVERLY AMPLIFIED...SO ALL FORCING SIGNALS A TAD MUTED...BUT NOT TO TAKEN LIGHTLY...ESPECIALLY GIVEN A CONSISTENT TREND IN THE BUFR SOUNDINGS /GFS AND WRF ALL SITES SOUTH OF I-90/ HAVING DEEP ISOTHERMAL LAYER FROM THE SFC-650MB THROUGH THE DURATION OF THE SNOW EVENT. IT/S IMPORTANT TO NOTE THAT THE LIFT SOMETIMES RESIDES ABOVE THIS REGION AT DIFFERENT LOCATIONS/TIMES...SO GREAT DENDRITIC GROWTH WILL NOT ALWAYS BE ATTAINED...HOWEVER...CERTAIN AREAS ARE APT TO SEE PROLONGED EFFICIENT SNOW PRODUCTION. THIS IS WHERE THE CRUX OF THE SNOW AMOUNT FORECAST BECOMES DIFFICULT. FROM A GFS/ECMWF STANDPOINT...FORCING SIGNALS A STEP WEAKER THAN NAM/SREF...AND HENCE TOTAL QPF FROM LATE TONIGHT INTO TUES NIGHT ABOUT 0.10 TO 0.15 LIGHTER THAN NAM/SREF MEAN. ORDINARILY NOT A BIG DEAL...BUT WITH EXPECTED RATIOS FROM 18/1 TO 25/1 /COBB ANALYSIS/...THAT QUICKLY BRINGS A 2-3 INCH DIFFERENCE AT ANY GIVEN POINT...AND WHILE NAM CONTINUES TO DRIFT NORTH...ALL OTHER MODELS HAVE TOO...AND THINK SREF MEAN /WHICH ALSO HAS DRIFTED NORTH WITH TIME/ PROBABLY CAPTURES THE AXIS MOST DEFINITIVELY...AND INCORPORATED THIS INTO FORECAST. AMOUNTS...EXPECT WIDESPREAD 3 TO 4 INCH AMOUNTS ALONG AND SOUTH OF INTERSTATE 90...GIVEN 20/1 RATIOS AVERAGED OVER THE STORM. CONCERN LIES WITH AN OVERALL FAVORABLE SETUP FOR LONG DURATION MOD SNOW WITH FAVORABLE DENDRITIC SOUNDINGS...MAKING NAM/WRF AND SREF MEAN TOTAL QPFS FROM 0.30 TO 0.40 VERY ACHIEVABLE. THIS WOULD SUGGEST A LONG DURATION EVENT OVER 6 INCHES...WITH SOME 7 TO 8 INCH AMOUNTS NOT OUT OF THE QUESTION ON WHATEVER LATITUDE /MOST LIKELY RST TO LSE TO MAUSTON/ THE HEAVIER BANDS/RATIOS BECOME ESTABLISHED. THERE MAY VERY WELL NEED TO BE A SHORT TERM UPGRADE TO WARNING GIVEN UNCERTAINTIES HERE...AND NEED TO RAISE AWARENESS THAT SNOW LIKELY TO FALL QUITE HEAVILY FROM TIME TO TIME ON MONDAY MORNING INTO THE AFTERNOON OVER THE FORECAST AREA. NAM-WRF HAS BEEN SCARY-CONSISTENT IN THIS TYPE OF SETUP...GFS AND ECMWF NOT NEARLY AS MUCH...AND PROBABLY OF MOST CONCERN...IS SREF MEAN QPF THAT CONTINUES TO INCREASE TOWARD OPNL NAM-WRF VALUES AND SHIFT NORTH MAKING THIS STORM DEAD-CENTER ON THE LA CROSSE FORECAST AREA. ISSUED HIGH-END SNOW ADVISORY FOR AREAS ALONG/SOUTH OF I-90...WITH CONCERN ANOTHER TIER OF COUNTIES TO THE NORTH MAY NEED TO BE ADDED. WINDS WILL COME UP AS STORM ENDS FOR TUESDAY...AND TEMPERATURES MOVE LITTLE. ANOTHER ARCTIC FRONT AND TEMP PLUNGE ON WED...WHICH WILL LIKELY FEATURE FALLING TEMPS AND PERHAPS BLOWING SNOW. .LONG TERM...THURSDAY THROUGH SUNDAY EXTENDED PORTION OF THE FORECAST WILL START ON A BITTERLY COLD NOTE ON THURSDAY MORNING IN WAKE OF MOST RECENT ARCTIC FRONTAL SURGE. WITH CONSISTENT GFS 925MB TEMPERATURES ONLY A FEW DEGREES WARMER THAN THIS PAST WEEKENDS NUMBERS...EXPECT WIDESPREAD SINGLE DIGITS AND TEENS BELOW ZERO...WITH COLD SPOTS IN CNTL WISCONSIN WELL INTO THE 20S BELOW ZERO. ONLY CAVEAT WILL BE A LITTLE WIND AS BIG 1037MB SFC HIGH SETTLES THROUGH WRN IA/ERN NEB. BUT WINDS HAVE CONSISTENTLY DECOUPLED IN MOST AREAS THE PAST FEW NIGHTS...SO EXPECT A FRIGID NIGHT. AS THE LARGE CNTL CONUS HIGH SETTLES SOUTH/EAST INTO THE SERN CONUS...STRONG WARM ADVECTION REGIME WILL QUICKLY DO ITS BEST TO SCOUR OUT REMNANT ARCTIC AIR. SHOULD SEE TEMPERATURES WARM QUICKLY AS HEIGHTS RISE DOWNSTREAM OF DEEP WRN CONUS TROUGHING...WHICH IS A MANIFESTATION OF SLOW PATTERN RETROGRESSION INTO A MEAN WRN TROUGH THROUGH THE EXTENDED. WILL SEE SEVERAL PIECES OF ENERGY EJECT OUT OF WRN TROUGH INTO CNTL CONUS THROUGH THE END OF WEEK INTO NEXT WEEKEND...WITH FRI/SAT WAVE SHOWING PROMISE FOR ACCUMULATING SNOW. MODELS VERY HIT/MISS ON AMPLITUDE/SPEED OF THIS WAVE...BUT DEGREE OF MOISTURE/WARM ADVECTION SUGGESTS MOISTURE WILL BE AMPLE TO TAP. MAINTAINED SNOW CHANCES FRI/FRI NIGHT IN ADVANCE OF THIS WAVE. MODERATING TEMPERATURES WILL LIKELY FINALLY GET US BACK TO NORMAL BY WEEKEND. && .AVIATION... CLEAR/GOOD VFR CONDITIONS AT THE TAF SITES EARLY IN THE PERIOD WILL DETERIORATE TO IFR BY MID MONDAY MORNING. INCREASING FORCING/LIFT/ MOISTURE FROM THE SOUTHWEST WILL SPREAD THICKENING/LOWERING CLOUDS ACROSS THE TAF SITES FROM LATE THIS AFTERNOON THRU ABOUT 09Z TONIGHT. AS LIFT/MOISTURE CONTINUE TO INCREASE AND LOWER LEVEL SATURATION OCCURS...LIGHT SNOW THEN MDT SNOW EXPECTED TO SPREAD FROM SOUTHWEST TO NORTHEAST ACROSS THE AREA BETWEEN 09Z-15Z...WITH CIGS/VSBYS LOWERING INTO THE IFR RANGE A COUPLE HOURS AFTER THE -SN STARTS. STRONGEST/DEEPEST LIFT TO SPREAD ACROSS THE AREA FROM MID- DAY MON INTO MON EVENING WITH IFR CONDITIONS/MDT SNOW THRU THE REST OF MON INTO MON NIGHT. SEVERAL INCHES OF SNOW POSSIBLE AT BOTH KRST/KLSE MON THRU MON NIGHT...FOR RUNWAY CLEARING/SNOW OPS ISSUES. BRISK WINDS ON TUE MAY CREATE SOME DRIFTING OF THE NEW FLUFFY SNOW...ESPECIALLY AT KRST. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...SNOW ADVISORY FROM 6 AM MONDAY TO MIDNIGHT CST MONDAY NIGHT FOR WIZ041-WIZ042-WIZ043-WIZ044-WIZ053-WIZ054-WIZ055-WIZ061. MN...SNOW ADVISORY FROM 6 AM MONDAY TO MIDNIGHT CST MONDAY NIGHT FOR MNZ086-MNZ087-MNZ088-MNZ094-MNZ095-MNZ096. IA...SNOW ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT CST MONDAY NIGHT FOR IAZ008-IAZ009-IAZ010-IAZ011-IAZ018-IAZ019-IAZ029-IAZ030. && $$ SHORT/LONG TERM...BINAU AVIATION...RRS wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 415 AM EST SUN JAN 20 2008 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS CONTINUES TO SHOW AN AMPLIFIED PATTERN ACROSS NORTH AMERICA...WITH STRONG RIDGING FROM THE EAST PACIFIC INTO NW CANADA...TROUGHING OVER THE PACIFIC NW... AND A BROAD UPPER TROUGH OVER THE EAST HALF OF CANADA. NW UPPER FLOW WHICH HAS BEEN OVER UPPER MI THE PAST FEW DAYS IS TURNING MORE WESTERLY...DUE TO THE COMBINATION OF THE DIGGING PACIFIC NW TROUGH AND A SHRTWV DROPPING SOUTH INTO SOUTHERN SASKATCHEWAN. THIS WESTERLY FLOW IS GRADUALLY BRINGING WARMER AIR INTO UPPER MI AS NOTED BY 850MB TEMP RISES OF 4C AT MPX AND INL BETWEEN 12Z AND 00Z. HOWEVER...THE AIRMASS STILL REMAINS COLD...GIVEN THE -24C READING AT INL AND -19C AT MPX. THUS...LAKE EFFECT CONTINUES OFF LAKE SUPERIOR. HOWEVER...THE BANDS ARE BECOMING MORE EAST-WEST ORIENTED THANKS TO THE UPPER LEVEL HEIGHT RISES SUPPORTING MORE WESTERLY LOW LEVEL FLOW...IN ADDITION TO LAND BREEZES WHICH HAVE DEVELOPED. TEMPS INLAND HAVE DROPPED INTO THE TEENS BELOW ZERO...BUT HAVE NOT DROPPED MUCH MORE DUE TO INCREASING HIGH CLOUDS IN THE UPPER FLOW. TO THE WEST...A FAIRLY POTENT SHRTWV CAN BE SEEN CROSSING NEVADA. DOWNSLOPING WESTERLY FLOW AHEAD OF THIS SHRTWV HAS CAUSED PRESSURE FALLS IN THE TEXAS PANHANDLE. FROM THE DEVELOPING LOW PRESSURE...A WARM FRONT EXTENDS NE INTO SW IOWA. && .DISCUSSION... MAIN FORECAST CONCERN IS SNOWFALL OVER THE KEWEENAW THROUGH TONIGHT. TODAY...SHRTWV OVER NEVADA WILL HEAD OUT INTO THE CENTRAL PLAINS... CAUSING THE TEXAS PANHANDLE LOW TO LIFT UP TOWARDS KANSAS CITY. MEANWHILE TO OUR NW...THE SHRTWV TROUGH OVER SOUTHERN SASKATCHEWAN IS PROGGED TO DROP DOWN INTO NORTH DAKOTA AND NW MN. THE COMBINATION OF BOTH FEATURES WILL RESULT IN THE UPPER FLOW TURNING SW...MORE FAVORABLE FOR BRINGING WARMER AIR INTO THE CWA. IN FACT...MODELS BRING 850MB TEMPS UP ABOUT 4C FROM CURRENT READINGS. THIS MAY NOT SEEM LIKE A WHOLE LOT...BUT IT SHOULD PRODUCE A MORE FAVORABLE ENVIRONMENT FOR DENDRITES COMPARED TO THE RECENT SMALLER SNOWFLAKES. THIS WILL PLAY A ROLE IN TWO DIFFERENT AREAS OF CONCERN. THE FIRST CONCERN IS THE POSSIBILITY OF SYNOPTIC PCPN WITH THE LOW LIFTING UP TOWARDS KANSAS CITY. MODELS DEPICT MID-LEVEL FRONTOGENESIS INCREASING OVER CENTRAL WI INTO NORTHERN LOWER MI DURING THE AFTN. GIVEN THE LOCATION OF THIS AXIS...AND THE PRESENCE OF A 120-130 JET STRETCHING FROM UPPER MI EASTWARD...FAVORING UPPER DIVERGENCE SOUTH OF THE CWA...THINK MUCH OF THE PCPN SHOULD STAY TO THE SOUTH. DRY AIR PRESENT OVER THE CWA AS INDICATED BY THE 00Z INL AND GRB SOUNDINGS SHOULD ALSO HOLD SYNOPTIC PCPN FROM MARCHING NORTH. WILL MAINTAIN CHANCE POPS...BUT RESTRICT THEM JUST TO THE SOUTH CENTRAL. THE OTHER PCPN CONCERN IS LAKE EFFECT SNOW. FOR THE EASTERN CWA...SOME LAKE EFFECT MIGHT LINGER FOR A FEW MORE HOURS PAST THE END TIME OF THE ADVISORY...BUT SEE NO NEED TO EXTEND THE ADVISORY AT THE PRESENT TIME. OVER THE KEWEENAW...LOW LEVEL WINDS ARE PROGGED TO BACK A LITTLE MORE SW THAN PREVIOUSLY THOUGHT...WHICH COULD MOVE THE CURRENT LAKE EFFECT COMPLETELY OFFSHORE FOR SOME OF THE KEWEENAW THIS AFTERNOON. THIS IS INDICATED BY THE NAM/GFS/LOCAL WRF-ARW RUN. HOWEVER...THE LOCAL WRF-ARW RUN DOES MANAGE TO BRING A CONVERGENT BAND BACK INTO THE KEWEENAW AFTER 20Z. FEEL THIS SOLUTION MIGHT BE THE BEST TO FOLLOW AS IT USUALLY HAS A BETTER HANDLE ON THE LAKE AGGREGATE. SOUNDINGS DEPICT AT LEAST SOME DENDRITIC GROWTH BETWEEN THE CLOUD BASE AND 850MB...WHICH MEANS WHEN THE CONVERGENT BAND MOVES IN...THERE COULD BE SOME DECENT SNOWFALL RATES. THEREFORE...HAVE LEFT THE GOING ADVISORY INTACT. GIVEN WARMER AIR MOVING IN...WARMER TEMPS ARE EXPECTED TODAY. ONLY MADE MINOR ADJUSTMENTS TO HIGHS. TONIGHT...SHRTWV TROUGH OVER NORTH DAKOTA IS PROGGED TO SHIFT EAST TOWARDS WESTERN LAKE SUPERIOR BY 12Z TUE. THIS TROUGH SHOULD HELP PROMOTE A RAPID PROGRESSION OF THE SHRTWV LIFTING UP FROM THE CENTRAL PLAINS...AND FAVOR THE GFS/UKMET IDEA OF BRINGING THE SHRTWV INTO LOWER MI BY 12Z WITH A WEAKER SFC LOW SITUATED NEAR ALPENA AT THE SAME TIME. THIS IS ALSO FAVORED BY HPC. MID-LEVEL FRONTOGENESIS AND UPPER DIVERGENCE FIELDS FROM THE GFS STILL SUGGEST THE BEST FORCING FOR PCPN TO REMAIN TO THE SOUTH...THOUGH ENOUGH CONFIDENCE EXISTS TO RAISE POPS TO LIKELY IN SOUTHERN MNM COUNTY. THE REST OF THE CWA WILL HAVE LOW CHANCE POPS...AND BOTH AREAS ARE FOR MAINLY IN THE EVENING AS THE MAIN MID-LEVEL FRONTOGENESIS AREA SHIFTS EAST AFTER 06Z. NEXT CONCERN IS WITH THE SHRTWV TROUGH...AS 850MB TEMPS FALL 1-2C. LOW LEVEL FLOW TURNS MORE WESTERLY IN THE EVENING...SO THE LAKE EFFECT BAND ENTERING THE KEWEENAW THIS AFTERNOON SHOULD REMAIN FAIRLY PROGRESSIVE...STALLING OUT AND WEAKENING OVER ONTONAGON COUNTY LATER IN THE NIGHT. HAVE EXTENDED THE ADVISORY FOR THE KEWEENAW TO 06Z TONIGHT TO ACCOUNT FOR THE LAKE EFFECT BAND. TO THE EAST...THE SWITCH TO MORE WEST TO EVEN NW WILL BRING THE EASTERN EXTENT OF THE BAND DOWN INTO LUCE/ALGER COUNTIES...FOLLOWED BY THE TYPICAL ONTARIO LAND BREEZE CONVERGENT BAND FROM NE LAKE SUPERIOR INTO LUCE COUNTY. THE REST OF THE CWA SHOULD SEE SOME CLEARING DURING THE OVERNIGHT HOURS TO ALLOW TEMPS TO FALL. WILL TREND TEMPS DOWNWARD GIVEN THIS CLEARING POSSIBILITY AND A DRY AIRMASS IN PLACE. TUE...SHRTWV TROUGH SWINGS INTO UPPER MI. WITH THIS TROUGH COMES ANOTHER COOL BLAST OF AIR...WITH 850MB TEMPS OF -24 TO -26C ENTERING WESTERN LAKE SUPERIOR BY 00Z WED. THUS...MORE LAKE EFFECT IS EXPECTED. SURFACE PATTERN SHOWS LAKE INDUCED TROUGHING SETTING UP...WITH LOW PRESSURE NEAR WHITEFISH POINT AND A TROUGH EXTENDING WEST THROUGH TWIN LAKES. THE HEAVIEST LAKE EFFECT SNOW...WHICH WILL NOT BE ALL THAT HEAVY GIVEN THE COLD AIR MOVING IN REDUCING SNOW TO WATER RATIOS...WILL BE CONFINED TO THE TROUGH AS IT PROVIDES A SOURCE OF CONVERGENCE. THUS...AGAIN THE WESTERN U.P. AND THE AREA FROM ALGER INTO NORTHERN LUCE COUNTY IS EXPECTED TO BE UNDER THE GUN FOR SNOW. DRY WEATHER IS EXPECTED FOR THE REST OF THE CWA...WITH TEMPS FAIRLY SIMILAR TO THOSE ON MON. TEMPS COULD FALL LATE IN THE DAY AS THE COLDER AIR MOVES IN. TUE NIGHT INTO WED...SHRTWV TROUGH HEADS OFF TOWARDS QUEBEC TUE NIGHT WHILE ANOTHER SHRTWV TROUGH DROPS SOUTH THROUGH SOUTH CENTRAL CANADA. THIS SECOND SHRTWV TROUGH...WITH A LITTLE MORE OF A COLD AIR PUNCH...SHOULD ENTER UPPER MI DURING THE DAY WED. THUS...CONTINUED LAKE EFFECT WITH CONTINUED BELOW NORMAL TEMPERATURES ARE EXPECTED. WIND FLOW DOES TURN A BIT MORE NORTHERLY WITH THE SECOND SHRTWV TROUGH WEDNESDAY MORNING...WHICH MEANS MARQUETTE AND WESTERN ALGER COUNTIES MAY PICK UP SOME SNOW. HOWEVER...THE MORE NORTHERLY WINDS DO NOT LAST LONG...AS MODELS SHOW ANY LAKE EFFECT BANDS HEADING OFF TOWARDS EASTERN ALGER COUNTY LATER WED AFTERNOON. EITHER WAY...IT STILL LOOKS LIKELY THAT ALL OF THE WESTERN COUNTIES WILL PICK UP MORE SNOW...THOUGH AGAIN WITH THE COLD 850MB TEMPS (DROPPING TO AROUND -26C BY 18Z WED) SUGGESTS FINER SNOWFLAKES. ONLY MINOR TWEAKS WERE MADE TO THE GOING LOW AND HIGH TEMPS. WED NIGHT INTO THU...THE PATTERN STARTS TO CHANGE DURING THIS PERIOD...AS THE SHRTWV TROUGH OVER THE CWA DIGS DOWN TOWARDS THE OHIO VALLEY AND THE CURRENT EAST PACIFIC RIDGE GETS PUSHED EASTWARD TOWARDS THE CWA. HOWEVER...850MB TEMPS EVEN AT 18Z THU ARE STILL DEPICTED BELOW -18C. NOT UNTIL 00Z DO 850MB TEMPS START TO GET WARM ENOUGH OVER WESTERN LAKE SUPERIOR TO ALLOW LAKE EFFECT TO END (-8 TO -10C) THUS...WITH WNW WINDS THROUGH THIS PERIOD...MORE LAKE EFFECT SNOW IS EXPECTED FOR THE WESTERN U.P. AND ALGER INTO NORTHERN LUCE COUNTIES. TEMPS COULD GET QUITE CHILLY WED NIGHT IF SKIES CAN CLEAR...AS NOTED BY MEX COOP GUIDANCE OF -20F AT CHAMPION. ALTHOUGH WE ARE WARM ADVECTING ON THU...TEMPS WILL STRUGGLE TO GET MUCH HIGHER THAN THE LOW TEENS...IF EVEN 10 ABOVE IN INLAND LOCATIONS. BEYOND THU...THE EAST PACIFIC RIDGE BUILDS INTO THE CWA FOR FRI...CAUSING 850MB TEMPS TO CLIMB TO PERHAPS AS HIGH AS -4C. MEX GUIDANCE RESPONDS ACCORDINGLY BY SHOWING HIGH TEMPS IN THE MID 20S. GIVEN THE GOOD AGREEMENT WITH THE 00Z ECMWF...HAVE RAISED HIGHS A FEW DEGREES. NO OTHER CHANGES MADE BEYOND FRIDAY. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... LES/GENERALLY IFR/LIFR VSBYS AND MVFR/OCNL IFR CIGS WL CONTINUE AT CMX INTO MON MRNG BEFORE BACKING LLVL FLOW AND ADVECTION OF STABLE/ DRY ARCTIC AIR CONSPIRE TO AT LEAST DIMINISH THE LES AND RESULT IN IMPROVING CONDITIONS ON MON. LATEST MODEL GUIDANCE HAS TRENDED FARTHER N WITH PLACEMENT OF LK INDUCED TROF N OF CMX. PER NAM MODEL FCST SDNGS...FCST IMPROVED VSBY TO VFR UNDER AN MFVR CIG TO ACCOUNT FOR THIS DVLPMNT. ALSO TRENDED BACK FCST ARRIVAL TIME OF THE TROF/ ONSET OF IFR CONDITIONS UNTIL LATE MON EVNG THAT IS STILL EXPECTED WITH VEERING FLOW IN THE WAKE OF DISTURBANCE PASSING TO THE S THRU THE CNTRL GRT LKS. SINCE SAW WL BE ON THE S SIDE OF THE LK INDUCED TROF AND UNDER THE DOMINATION OF DRY...CONTINENTAL ARCTIC AIR...EXPECT VFR CONDITIONS THERE THRU THE PD. BUT THERE WL BE AN INCRS IN HI/MID CLDS STARTING LATE TNGT COINCIDENT WITH THE PASSAGE OF THE DISTURBANCE TO THE S. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NORTHWEST WINDS IN THE 15 TO 30 KT RANGE WILL GRADUALLY BACK TO SOUTHWEST OR WEST AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. LOW PRESSURE WILL MOVE FAR ENOUGH SOUTH OF THE AREA SO THAT LAKE INDUCED TROUGHING TONIGHT INTO TUE WILL KEEP MAINLY W OR WSW WINDS GOING OVER THE SOUTH PORTION OF THE LAKE AND NW WINDS OVER THE NORTH HALF WITH WIND VALUES MAINLY IN THE 15 TO 25 KT RANGE. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY BY WED. HEAVY FREEZING SPRAY WILL CONTINUE THIS MORNING DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. HEAVY FREEZING SPRAY WILL AGAIN DEVELOP TUESDAY NIGHT INTO WEDNESDAY AS A REINFORCING BATCH OF ARCTIC AIR AND STRONGER WINDS MOVES IN. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ001-003. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ002. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR MIZ006-007. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ248-250. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...KC MARINE...JLB mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 504 AM MST MON JAN 21 2008 .UPDATE... A QUICK UPDATE TO ISSUE A DENSE FOG ADVISORY FOR EL PASO COUNTY. LIVE WEBCAMS ARE SHOWING FAIRLY POOR VISIBILITIES ACROSS MUCH OF COLORADO SPRINGS. THIS IS NOT SURPRISING GIVEN THE CLEAR NIGHT LAST NIGHT AND LCL HEIGHTS ARE PRETTY CLOSE TO THE GROUND. GIVEN THE LIGHT SOUTH-SOUTHEAST UPSLOPE WIND ACROSS EL PASO COUNTY...I DON`T SEE ANY REASON WHY THE FOGGY CONDITIONS WOULD IMPROVE THIS MORNING. A DIFFICULT MORNING COMMUTE WILL BE LIKELY FOR EL PASO COUNTY THIS MORNING. ALSO...THIS IS DENSE FREEZING FOG...SO FREE- AIR SURFACES...LIKE BRIDGES/OVERPASSES...COULD BECOME SLICK IF NOT TREATED. METZE && .PREV DISCUSSION... /ISSUED 432 AM MST MON JAN 21 2008/ SHORT TERM... (TODAY AND TONIGHT) ..COMPLEX WEATHER PATTERN TODAY/TONIGHT... CURRENTLY...COLD FRONT WAS FASTER LAST NIGHT...BY ABOUT 6-9 HOURS. 07Z/21 SURFACE ANALYSIS HAD THE COLD FRONT FROM KTAD AND TRANSITIONING TO A STATIONARY FRONT JUST SOUTH OF KSPD INTO KS. 1030-1040MB HIGH PRESSURE WAS ACROSS THE NORTHERN ROCKY MOUNTAINS INTO THE NORTHERN PLAINS. ASSOCIATED LIFR-MVFR CEILINGS WERE ACROSS MUCH OF EASTERN CO WITH TERRAIN PLAYING A BIG PART RIGHT NOW. STRATUS HAS NOT MADE IT INTO COLORADO SPRINGS YET GIVEN THE NORTHERLY DOWNSLOPE FLOW OFF THE PALMER DIVIDE...HOWEVER KCOS WIND HAS TURNED EASTERLY AND "FOG" SATELLITE IMAGERY IS SHOWING STRATUS SPREADING INTO SOUTHERN EL PASO COUNTY. THE STRATUS HAS WORKED ITS WAY UP THE LOWER AR RIVER VALLEY AND CONTINUES TO FILL-IN ALONG AND SOUTH OF HIGHWAY 50. REGIONAL RADARS ARE NEARLY ECHO ENERGY-FREE AT THE MOMENT. EVERY ONCE IN A WHILE...A METAR REPORTS LIGHT SNOW OR FLURRIES ACROSS NORTHEAST CO. LIVE WEB CAMS NOT SHOWING MUCH EITHER...EXCEPT FREEZING FOG(AND SOME FREEZING DRIZZLE) AROUND MONUMENT. MEANWHILE...WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES REVEALED A RELATIVELY DEEP "DRY" WEST-SOUTHWEST FLOW ACROSS MUCH OF SOUTHERN CO AND THE DESERT SOUTHWEST. THE AREA OF LOW PRESSURE WAS SPINNING WELL WEST OF CO ACROSS OR...AND TRENDING TOWARDS A WESTWARD MIGRATION. IT IS RATHER BRISK-VERY WINDY ACROSS THE VERY HIGH TERRAIN PER AWOS SENSORS. PIKES PEAK SENSOR REPORTING SUSTAINED 49 MPH WITH GUSTS AROUND 70 MPH. TEMPERATURES ARE IN THE SINGLE DIGITS AND TEENS ACROSS MUCH OF SOUTHEAST CO...AND OF COURSE...ALAMOSA IS APPROACHING -20F. TODAY AND TONIGHT...VERY COMPLEX WEATHER PATTERN OVER THE NEXT 12-24 HOURS. THERE WILL BE QUITE THE DICHOTOMY OF SENSIBLE WEATHER. RATHER VIGOROUS WEST-SOUTHWEST FLOW ALOFT WILL CONTINUE ACROSS THE CENTRAL ROCKIES. BRISK-VERY WINDY CONDITIONS WILL BE FELT ACROSS THE HIGHER MOUNTAINOUS TERRAIN AND I WOULDN`T BE SURPRISED TO SEE WIND GUSTS OF 40-65 MPH ACROSS THE MOUNTAIN PEAKS AND EASTERN SLOPES OF MOST OF OUR MOUNTAINS...ESPECIALLY THE NORTHERN SANGRE DE CRISTO MOUNTAINS GIVEN THE RELATIVELY STRONG WEST-SOUTHWEST FLOW ORTHOGONAL TO THE BARRIER. VERY S51OW CP AIR MASS SHOULD REMAIN WEDGED UP AGAINST OUR EASTERN CO MOUNTAINS AND SOUTHEAST CO PLAINS. WILL TRY FOR A LITTLE TEMPERATURE RECOVERY ALONG AND EAST OF THE I-25 CORRIDOR... BUT IT LIKELY WILL NOT BE MUCH. THE SAN LUIS VALLEY CENTER FLOOR WILL CONTINUE TO BE A TEMPERATURE FORECAST C51ENGE. IF THE SOUTHWEST WINDS CAN PICK UP...THEN TEMPERATURES COULD SHOOT INTO THE 20S/30S...HOWEVER...IF THE WINDS REMAIN LIGHT...THEN HIGH TEMPERATURES WILL STRUGGLE TO GET INTO THE TEENS. AS FOR PRECIPITATION...THE BEST DEEP MOISTURE SHOULD BE AROUND THE SAWATCH AND MOSQUITO MOUNTAIN RANGES AND THIS IS WHERE THE HIGHEST POPS WILL BE LOCATED. A COUPLE OF INCHES OF SNOW CAN BE EXPECTED. PRECIPITATION WILL BE QUITE THE C51ENGE ACROSS OUR EASTERN CO MOUNTAINS AND ADJACENT PLAINS. THE 700-300MB LAYER IS RELATIVELY "DRY"...ESPECIALLY ACROSS THE FAR SOUTHEAST CO PLAINS. THIS DOESN`T PROMOTE ANY "SEEDER-FEEDER" ICE CRYSTAL PRECIPITATION FALLING FROM ABOVE...SO ANY PRECIPITATION WOULD BE LOW LEVEL DRIVEN AND VERY LIGHT. GIVEN THE THERMAL STRUCTURE...I WOULD THINK LIGHT SNOW AND DEFINITELY FLURRIES WOULD BE THE GREATEST THREAT. I WILL TRY TO ADD SOME PRECIPITATION VALUE TO THE FORECAST BY GOING WITH S--(LIGHT SNOW AND FLURRIES) FOR ALONG AND EAST OF I-25 CORRIDOR TODAY AND TONIGHT. THERE COULD BE THE POTENTIAL FOR FREEZING DRIZZLE/FREEZING FOG GENERALLY WEST OF THE I-25 CORRIDOR TOWARDS THE MOUNTAINS WHERE THE LCL HEIGHT WILL BE NEAR THE GROUND. LATEST MODEL DATA AND SOUNDINGS SUGGEST THE COLORADO SPRINGS AREA TO HAVE LIFR-IFR STATUS/FREEZING FOG TONIGHT WITH SURFACE-PBL FLOW SOUTH-SOUTHEASTERLY UP THE SOUTHERN PORTION OF THE PALMER DIVIDE. MINIMUM TEMPERATURES ALONG AND EAST OF THE I-25 CORRIDOR WILL GREATLY DEPEND ON THE CLOUD COVER. IF THE LIFR-MVFR STRATUS CLEARS...THEN TEMPERATURES WILL TANK. HOWEVER...IF THE CLOUD COVER REMAINS...THEN TEMPERATURES WILL DROP SLOWLY AND JUST A LITTLE. METZE LONG TERM... (TUESDAY THROUGH SUNDAY) ZONAL TO UPPER RIDGING PATTERN PROJECTED TO OCCUR OVER CWFA FROM TUESDAY INTO THURSDAY MORNING ALLOWING FOR GENERALLY DRY CONDITIONS...EXCEPT FOR PORTIONS OF THE WESTERN AND CENTRAL MOUNTAINS. TEMPERATURES EXPECTED TO MODERATE SLOWLY EACH DAY FROM TUESDAY INTO THURSDAY BUT CONTINUE TO REMAIN BELOW LATE JANUARY SEASONAL AVERAGES. RELATIVELY MOIST SOUTHWEST FLOW ALOFT IS PROJECTED TO PRIMARILY IMPACT THE WESTERN MOUNTAINS WITH POPS FROM LATER THURSDAY INTO SUNDAY...WHILE EASTERN PORTIONS OF THE CWFA SHOULD REMAIN GENERALLY PRECIPITATION FREE. INCREASING WINDS ARE ALSO ANTICIPATED TO DEVELOP FROM LATER THURSDAY INTO SUNDAY. FINALLY...TEMPERATURES RUNNING NEAR CLIMATOLOGICAL AVERAGES SHOULD BE NOTED FROM FRIDAY INTO SUNDAY. AVIATION... PER SHORT TERM DISCUSSION...VFR CONDITIONS WILL CONTINUE AROUND THE ALS TERMINAL. FOR THE COS TERMINAL AREA...IFR CEILINGS WILL DEVELOP BETWEEN 10Z-13Z/21 AND CONTINUE MUCH OF TODAY AND TONIGHT. LIGHT SNOW OR FLURRIES WITH VISIBILITIES OF 1-4 MILES COULD OCCUR AROUND THE COS TERMINAL AREA THROUGH 12Z/22 WITH THE POTENTIAL OF 1/4-1/2SM IN FZFG AND LIFR STRATUS BETWEEN 10Z-16Z/21 AND AGAIN AFTER 02Z/22. FOR THE PUB TERMINAL AREA...IFR-MVFR CEILINGS WILL OCCUR WITH FLURRIES POSSIBLE THROUGH 12Z/22. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL NOON MST TODAY FOR COZ084-085. && $$ 17/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 828 AM EST MON JAN 21 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD IN TODAY AND BRINGING AN END TO THE LAKE EFFECT SNOWS. THE HIGH WILL DOMINATE TONIGHT. A LOW PRESSURE SYSTEM WILL MOVE ACROSS THE GREAT LAKES REGION TUESDAY AND THROUGH THE SAINT LAWRENCE VALLEY TUESDAY NIGHT DRAGGING A COLD FRONT ACROSS THE REGION. THIS SYSTEM WILL BRING LIGHT SNOW TO THE AREA. ANOTHER SHOT OF ARCTIC AIR IS ON THE WAY FOR LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 06Z RUN OF THE NAM12...CURRENT HOURLY RUC13 AND BUF-WRF ARE DOING QUITE WELL WITH PLACEMENT AND INLAND EXTENT OF LAKE EFFECT BAND OFF LAKE ONTARIO. THE NEXT COUPLE OF HOURS (TO AROUND 16Z)...THIS BAND OF SNOW SHOULD BEGIN TO LIFT NORTHWARD AS LOW LEVEL FLOW BACKS AROUND DUE TO THE PERIPHERY OF THE SURFACE HIGH SLIDING BY TO OUR SOUTH AND INVERSION HEIGHTS LOWERING WITH RISING HEIGHTS. SINCE WE HAVE NOT MET WARNING CRITERIA AND ADDITIONAL AMOUNTS OF SNOW ARE EXPECTED TO BE AROUND 3 INCHES OR LESS...DOWNGRADED THE WARNING TO AN ADVISORY AT THIS TIME. THIS BAND WILL CONTINUE TO LIFT NORTHWARD AND BY THIS AFTERNOON...ANTICIPATE LAKE EFFECT CONCERNS WOULD HAVE DIMINISHED. NO OTHER CHANGES NEEDED AT THIS TIME. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY NIGHT/... GET A BIT OF A BREAK TONIGHT WITH RIDGE DOMINATING WEATHER. SURFACE HIGH CENTERED OVER OHIO VALLEY WILL SHIFT EASTWARD AND MORE MOVE OFF THE MID ATLANTIC COAST TONIGHT. LOW PRESSURE SYSTEM WILL MOVE OUT THE PLAINS TODAY HEADING TOWARD THE GREAT REGION. THE LOW WILL MOVE ACROSS THE GREAT LAKES TUESDAY INTO QUEBEC TUESDAY NIGHT DRAGGING ITS COLD FRONT ACROSS THE LOCAL AREA. EVEN WITH LOW PASSING TO OUR WEST THE COLD AIRMASS IN PLACE WILL KEEP A SINGLE P-TYPE...SNOW...WITH LIGHT QPF AMOUNTS. IN THE WAKE OF THIS SYSTEM ANOTHER ROUND OF LAKE EFFECT SNOWS EXPECTED. LONG WAVE TROUGH WILL GET REINFORCED OVER THE REGION WEDNESDAY AS MORE NORTHERN STREAM ENERGY DIVES OUT OF CENTRAL CANADA. CONDITIONS WILL BE SEASONABLE WITH THE THREAT OF SNOW SHOWERS. && .LONG TERM /THURSDAY THROUGH SUNDAY/... ON THURSDAY THE 500 HPA TROF DIGS SOUTH AND BEGINS TO MOVE EAST OF NEW ENGLAND INTO THE ATLANTIC AS A RIDGE MAKES ITS WAY EAST FROM THE ROCKIES TO THE MISSISSIPPI VALLEY...AND A STRONG SURFACE HIGH BUILDS INTO THE OHIO VALLEY. TEMPERATURES WILL DROP THURSDAY NIGHT AS A STRONG GRADIENT ON THE WEST SIDE OF THE UPPER TROF DRAWS COLD AIR OUT OF CENTRAL CANADA INTO THE REGION AND WE MAY BE DEALING WITH WIND CHILL ISSUES AS A RESULT. BY FRIDAY EVENING THE SURFACE HIGH IS FORECAST TO BE OVER TIDEWATER VIRGINIA...WITH A LOW LEVEL FLOW OF SOMEWHAT WARMER AND MOISTER AIR FLOWING INTO THE OHIO VALLEY FROM THE SOUTHERN PLAINS AROUND THE WEST SIDE OF THE HIGH. MEANWHILE A CLIPPER TYPE LOW RACES ACROSS SOUTHERN CANADA FROM NORTH OF MONTANA ON FRIDAY TO NORTH OF LAKE HURON BY SATURDAY EVENING. TEMPERATURES ARE EXPECTED TO MODERATE OVER THE WEEKEND...WITH HIGHS WARMING INTO THE 25 TO 35 DEGREE RANGE SATURDAY AFTERNOON. THE CLIPPER WILL BRING A CHANCE OF SNOW TO THE NORTHERN AND WESTERN ZONES STARTING SATURDAY WITH MORE WIDESPREAD WARMING AND CHANCE OF PRECIP ON SUNDAY WITH HIGHS MIDDAY SUNDAY 30 TO 40 DEGREES...ABOUT FIVE DEGREES ABOVE NORMAL...BEFORE THE LOW SWEEPS A FRONT THROUGH THE REGION LATE SUNDAY. IT WILL BE WARM ENOUGH IN MUCH OF THE HUDSON VALLEY MIDDAY SUNDAY FOR THE SNOW TO MIX WITH...OR EVEN CHANGE TO RAIN. && .AVIATION /13Z MONDAY THROUGH FRIDAY/... A WEAK FRONT LAY ACROSS THE MOHAWK VALLEY EARLY THIS MORNING WHICH SERVED AS A FOCUS FOR SOME LIGHT SNOW SHOWERS ALONG WITH SOME MOISTURE WHICH CAME DOWN THE MOHAWK VALLEY FROM LAKE ONTARIO. FOR THE MOST PART...THE AIR MASS WAS LACKING MOISTURE AT THE SURFACE WITH DEW POINTS IN THE HUDSON VALLEY TEN DEGREES BELOW THE AIR TEMPERATURE AND ONLY A VERY LIGHT TRACE OF SNOW FELL IN THE ALBANY AREA OVERNIGHT. FOR THE MOST PART VFR FLIGHT CONDITIONS WILL PREVAIL WITH LOCALIZED MVFR LAKE AND TERRAIN CAUSED LOW CLOUDS AND SNOW SHOWERS IN THE MOHAWK VALLEY...BERKSHIRES...AND THE SOUTHERN GREEN MOUNTAINS OF VERMONT. WINDS EARLY THIS MORNING WERE LIGHT FROM THE SOUTHWEST BUT ARE EXPECTED TO VEER WEST AND INCREASE TO BETWEEN 10 AND 12 KNOTS BY MID MORNING WITH GUSTS AS HIGH AS 25 KNOTS IN THE ALBANY AREA RESULTING FROM FUNNELING DOWN THE MOHAWK VALLEY. THE WINDS ARE LIKELY TO BRING A BROKEN TO OVERCAST DECK AROUND 4500 FEET ASL OFF THE LAKE WITH CLEAR TO SCATTERED CLOUDS NORTH AND SOUTH OF THE BAND OFF THE LAKE. LATE THIS AFTERNOON AS THE HIGH BUILDS INTO THE REGION THE WINDS WILL SLACKEN TO 5 TO 10 KNOTS AND THE LOW CLOUDS IN THE MOHAWK VALLEY WILL BECOME SCATTERED AS A BROKEN DECK OF MIDLEVEL CLOUDS MOVES IN FROM THE WEST. THESE CLOUDS ARE FORECAST TO THICKEN AND LOWER FROM THE ALBANY AREA NORTH TONIGHT BUT BECOME SCATTERED FARTHER SOUTH...WITH WINDS TONIGHT BECOMING LIGHT FROM THE SOUTHWEST OR CALM. OUTLOOK... TUE...BECOMING MVFR/IFR WITH CHC OF SNOW...LOW CIGS AND VSBY IN PM. WED...MVFR/IFR EARLY AM...LOW CIGS/VSBY AND CHANCE OF LINGERING SHSN. THU...VFR/MVFR...CHANCE OF -SHSN. FRI...VFR...NO SIG WX. && .HYDROLOGY... NO HYDRO PROBLEMS ARE EXPECTED THE NEXT SEVERAL DAYS. AN ARCTIC COLD FRONT WILL MOVE THROUGH ON SATURDAY AND ANY PRECIPITATION FROM SATURDAY INTO THE MIDDLE OF NEXT WEEK IS EXPECTED TO BE IN THE FORM OF SNOW. WITH THE VERY COLD AIRMASS IN PLACE ACROSS THE REGION FROM SATURDAY NIGHT THROUGH THE MIDDLE OF NEXT WEEK...THIS WILL RESULT IN RAPID FORMATION OF ICE AGAIN ON THE MAIN STEM RIVERS IN THE HYDRO SERVICE AREA. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ032-038. MA...NONE. VT...NONE. && $$ NEAR TERM...BGM FOR THE LATEST UPDATES...PLEASE VISIT OUR WEBPAGE AT WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SHREVEPORT LA 950 AM CST MON JAN 21 2008 .DISCUSSION... CURRENT GRIDS LOOK TO BE IN GOOD SHAPE. 12Z KSHV RAOB SUGGESTS AFTERNOON TEMPS TOPPING OUT IN THE LOWER TO MID 50S...BUT THIS SEEMS UNREASONABLE...W/SHORTWAVE JUST ENTERING WESTERN ZONES...AND ASSOCIATED CLOUD DECK PERSISTING THRU THE AFTERNOON. KTXK REPORTING UP ON THE LATEST OB...BUT LATEST RUC SOUNDINGS SUGGEST THIS WILL BE BRIEF. NO UPDATES. && .AVIATION... CLOUDS CONTINUE TO SPREAD OVER FORECAST AREA...WITH CIGS AROUND 5 THSD FT. CIGS WILL GRADUALLY LOWER THROUGHOUT THE DAY...EVENTUALLY BECMG IFR AFTER 22/06Z AND CONTINUING UNTIL 22/18Z. VSBYS MOSTLY VFR THROUGH 00Z...WITH AREAS OF MVFR FROM 00Z THROUGH 06Z... THEN FREQUENT VSBYS 1-3 MI IN RAIN AND FOG FROM 06Z UNTIL 22/18Z. WINDS SOUTHEAST 10-15 KTS THROUGHOUT THE PERIOD. OUTLOOK FOR AFTER 22/18Z TUESDAY...MVFR DUE TO CIGS AND RAIN BUT VSBYS GRADUALLY BECMG VFR ALL AREAS BY 23/00Z. && .PREV DISCUSSION... /ISSUED 729 AM CST MON JAN 21 2008/ DISCUSSION... QUICK ZONE UPDATE JUST SENT TO DROP TEMPORAL MENTION OF UNAUTHORIZED SHOWERS OVER NE TX/WRN LA. BELIEVE SHOWERS SHOULD WEAKEN AS THEY MOVE FARTHER E AWAY FROM BEST ISENTROPIC FORCING ASSOCIATED WITH THE SSW LLJ OVER CNTRL TX...AT LEAST UNTIL LLJ AXIS NUDGES FARTHER E INTO E TX LATE THIS AFTERNOON...AND ACROSS THE REMAINDER OF THE AREA TONIGHT. SHOWERS DEVELOPING REMAIN VERY SHALLOW...ONLY SOME 5-6KFT DEEP...THUS ONLY TRACE TO ONLY A FEW HUNDRETHS QPF AT MOST ARE EXPECTED UNTIL LATER THIS AFTERNOON/TONIGHT. UPDATE ALREADY OUT. 15 PREV DISCUSSION... /ISSUED 507 AM CST MON JAN 21 2008/ DISCUSSION... EXTENSIVE LOW CLOUD DECK CONTINUES TO STREAM NE IN A HURRY ACROSS SE OK/SW AR/E TX ALONG A 40-45KT SSW LLJ THIS MORNING...AND SHOULD RAPIDLY ENCOMPASS THE REST OF SW AR/N LA BY MIDDAY. THE LLJ IS ACTUALLY MIXING SOME OF THE WINDS DOWN TO THE SFC AS WELL...ESPECIALLY OVER E TX...PUTTING THE BRAKES ON THE TEMPERATURE SLIDE...WITH TEMPS EXPECTED TO SLOWLY WARM A FEW DEGREES BY SUNRISE. STEEP CAPPING INVERSION ABOVE THE CLOUD LAYER WILL MAINTAIN THIS CLOUDINESS IN OVER THE AREA TODAY...WITH PROGS CONTINUING TO INDICATE GOOD ISENTROPIC FORCING ALONG THE 290-295K SURFACES ESPECIALLY OVER CNTRL TX TODAY...GRADUALLY SHIFTING E INTO SE OK/EXTREME SW AR/WRN E TX BY LATE THIS AFTERNOON. MEANWHILE...LEAD SHORTWAVE IS EJECTING E ACROSS AZ THIS MORNING...AHEAD OF DEVELOPING CLOSED LOW OFF THE NRN CA COAST. AS THIS SHORTWAVE IS ABSORBED INTO THE WESTERLIES TODAY...UPPER JET MAX NEAR 140KTS WILL TRAVERSE E ACROSS TX BY THIS EVENING...WITH THE REGION LYING IN THE LFQ OF THE MAIN JET OVERNIGHT ALONG THE AXIS OF BEST ISENTROPIC FORCING ASSOCIATED WITH THE LLJ. FAVORABLE LAPSE RATES IN THE 700-500MB LAYER DOES YIELD AN ISOLATED ELEVATED THUNDER THREAT OVERNIGHT. THUS...EXPECTING SHOWERS/ISOLATED CONVECTION TO INCREASE IN COVERAGE THIS EVENING...BUT STILL HAVE MY QUESTIONS AS TO EXACTLY HOW EXTENSIVE COVERAGE WILL BE. THE MOISTURE PROFILE WILL BE SOMEWHAT SHALLOW...AND THERE WILL BE A LACK OF LARGE SCALE FOCUSING MECHANISMS...WITH OUR NEXT COLD FRONT STILL LYING IN WAIT FARTHER NW ACROSS NRN OK/SE KS. THUS...THIS EVENT LOOKS TO BE ANOTHER HIGH POP/LOW QPF EVENT...WITH RAINFALL AMOUNTS GENERALLY AROUND A QUARTER OF AN INCH OR LESS. NEXT LONGWAVE TROUGH WILL DROP SE INTO THE MS VALLEY TUESDAY...WHICH WILL GIVE THIS NEXT COLD FRONT A PUSH SE TOWARDS THE AREA...NEARING THE I-30 CORRIDOR OF NE TX/SW AR AROUND 12Z TUESDAY...SLIGHTLY FASTER THAN THE ECMWF/NAM RUNS SUNDAY. HOWEVER...FRONT WILL BE SHALLOW...WITH COLD ADVECTION LIKELY LAGGING THE FRONT A WAYS. THUS...AS DEEP LAYER FLOW BECOMES WRLY BETWEEN 12-18Z...AND ENDING THE RAIN THREAT...COULD SEE BREAKS IN THE LOW CLOUDS FOR TEMPS TO WARM IN WAKE OF THE FROPA. NOT VERY CONFIDENT IN THE NUMBERS BEING SPIT OUT FOR MAX TEMPS TUESDAY...THUS HAVE TRIMMED VALUES BACK A BIT NW OF I-30...AND GENERALLY ACCEPTED THE NUMBERS ELSEWHERE AWAY FROM THE DEEPER COLD AIR. DESPITE A FAIRLY BENIGN WEDNESDAY FORECAST...THE SUBTROPICAL JET WILL BECOME ACTIVE ONCE AGAIN...USHERING ABUNDANT ELEVATED PACIFIC MOISTURE E ACROSS TX/LA AS EARLY AS TUESDAY NIGHT. THE GFS/ECMWF CONTINUES TO GENERATE VERY LIGHT QPF AMOUNTS OVER E TX/N LA S OF I-20...MAINLY FROM ELEVATED PRECIP. HOWEVER...COULD SEE ENOUGH OF THIS ELEVATED PRECIP ACTUALLY REACH THE GROUND...AND FORECAST SOUNDINGS DO SUPPORT ENOUGH EVAPORATIVE COOLING SUCH THAT IP COULD MIX IN WITH VERY -RA. HOWEVER...BOTH MODELS ALSO SUGGEST A 2ND SHORTWAVE DROPPING SE ACROSS THE MS VALLEY WEDNESDAY NIGHT...WHICH WOULD SHIFT MUCH COLDER/DRIER AIR SE /OUR NEXT REINFORCING ARCTIC AIR MASS/ AND LIMIT ANY KIND OF PRECIP. THUS...NOT ENOUGH CONFIDENCE ATTM TO ADD ANY WINTRY MIX TO THE FORECAST GIVEN THIS SMALL TIMETABLE...BUT LATER SHIFTS WILL CONTINUE TO MONITOR. IN ANY CASE...IT DOESN/T LOOK TO POSE A SIGNIFICANT THREAT AS SFC TEMPS IN THESE AREAS SHOULD BE JUST ABOVE FREEZING WEDNESDAY NIGHT. A MORE SW FLOW ALOFT IS ESTABLISHED BY LATE THURSDAY UNDER THIS NEW ARCTIC AIR MASS...ALTHOUGH DETAILS ARE A BIT SKETCHIER IN REGARDS TO THE EVOLUTION/TRACK OF THE W COAST CLOSED LOW...WITH THE GFS MORE AGGRESSIVE IN KICKING THIS LOW E LATE THURSDAY THAN THE MUCH SLOWER ECMWF. IN ANY CASE...IT APPEARS ELEVATED PACIFIC MOISTURE WILL INCREASE ONCE AGAIN LATE THURSDAY...WHICH COULD ALSO YIELD A WINTRY MIX OVER MUCH OF THE AREA. HOWEVER...RETURN FLOW INCREASES BY THIS TIME...WITH SRLY LLJ ESTABLISHED OVER TX. AMOUNT OF WARM ADVECTION WILL DETERMINE WHETHER OR NOT A LIGHT WINTRY MIX WILL OCCUR...AND STILL DO NOT HAVE ENOUGH CONFIDENCE TO ADD TO THE FORECAST EITHER...GIVEN SO MANY UNCERTAINTIES. HOWEVER...THE GFS HAS REMAINED CONSISTENT IN RECENT DAYS WITH THE EJECTION OF THE WEST COAST LOW INTO THE WESTERLIES...SUCH THAT RAIN CHANCES WILL RETURN FOR MUCH OF NEXT WEEKEND. PRELIMS ARE LISTED BELOW. 15 AVIATION... SC CONTINUES TO ROLL ACROSS E TX EARLY THIS MORNING...WITH BKN-OVC CIGS AROUND FL060. WITH SURFACE RIDGING NOW TO OUR E...BOUNDARY LAYER WINDS SHOULD REMAIN SOUTHERLY THROUGH MOST OF TODAY. AS SUCH...I EXPECT THE CLOUD COVER TO WORK ITS WAY E. JUST ABOUT ALL TERMINALS SHOULD SEE VFR FLIGHT CATEGORIES THROUGH 22/0000 UTC... WITH OVC CIGS AROUND FL050 OR HIGHER. ISENTROPIC UPGLIDE IS SLATED TO RETURN TO E TX THIS AFTERNOON...AND I WOULD NOT BE SURPRISED TO SEE ISOLATED -SHRA AT KLFK...KTYR...OR KGGG AFTER 2100 UTC OR SO. I AGREE WITH THE PUBLIC FORECASTER THOUGH IN THAT MOST OF THE SHRA SHOULD WAIT UNTIL AFTER 22/0000 UTC WHEN SLIGHTLY BETTER FORCING ARRIVES. PRECIPITATION TIMING FOR THE 1200 UTC TAF PACKAGE LOOKS TO BE FAIRLY CLOSE TO ONGOING TAFS AND I PROBABLY WILL NOT DEVIATE MUCH. LOW CIGS SHOULD REDUCE FLIGHT CATEGORIES TO IFR THIS EVENING FOR THE REMAINDER OF THE TAF PACKAGE. OUTLOOK FOR TUESDAY...MVFR WITH REDUCTIONS TO IFR POSSIBLE. /BUTTS/ && .PRELIMINARY POINT TEMPS/POPS... SHV 49 44 55 31 / 20 60 30 0 MLU 50 42 55 32 / 10 50 50 0 DEQ 43 35 44 19 / 30 50 30 0 TXK 47 40 48 27 / 20 60 30 0 ELD 48 39 49 26 / 10 60 50 0 TYR 49 43 51 29 / 30 50 20 0 GGG 49 44 52 30 / 20 50 20 0 LFK 52 50 61 36 / 20 50 30 0 && .SHV WATCHES/WARNINGS/ADVISORIES... AR...NONE. LA...NONE. OK...NONE. TX...NONE. && $$ 14/44 la AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 954 AM CST MON JAN 21 2008 .DISCUSSION...MAX TEMP FORECAST WHERE SKIES ARE CURRENTLY CLEAR (ACROSS THE N FA) IN GOOD SHAPE. CURRENT TEMPS IN -10F TO -20F AND EXPECT SOLAR TO PROVIDE 8F TO 13F RECOVERY. CURRENT TEMPS WHERE SKIES ARE CURRENTLY CLOUDY (ACROSS THE S FA) NOW ZERO TO -5F. CLOUDS EXPECTED TO EXIT MUCH OF THIS AREA BY AFTERNOON...AND ENTIRE AREA BY LATE AFTERNOON. THINK AT LEAST 5F RECOVERY POSSIBLE AND WILL RAISE MAX TEMPS ACCORDINGLY ACROSS THIS AREA. && .AVIATION...KFAR/KBJI WILL SEE SOME BROKEN SKIES THROUGH A GOOD PORTION OF THE DAY. LIGHT FLURRIES WITH TEMPO VISIBILITIES DOWN TO 5 MILES POSSIBLE. BOTTOM LINE IS PREDOMINANTLY VFR CONDS THROUGH PERIOD. KGFK SHOULD BE MOSTLY CLEAR THROUGH THE DAY. && .PREV DISCUSSION... /ISSUED 906 AM CST MON JAN 21 2008/ UPDATE...CURRENT OBS INDICATE FLURRIES UNDER CLOUD COVER ACROSS THE SOUTHERN FA. 12Z NAM/RUC SHOWING WEAK MID-LEVEL FRONTOGENESIS. THIS FORCING WILL SLOWLY SHIFT SE THROUGH THE DAY ALONG WITH CLOUD COVER. 12Z NAM/RUC A BIT SLOWER WITH SHIFTING CLOUD COVER TO THE SE AND WILL ADJUST SKY GRIDS ACCORDINGLY. INTRODUCED FLURRIES. DO NOT HAVE A GOOD HANDLE ON TEMPERATURE FOR TODAY...BUT CURRENT MAXT GRID LOOKS REASONABLE. WILL UPDATE AGAIN IF TEMPS NEED ADJUSTMENT. PREV DISCUSSION... /ISSUED 359 AM CST MON JAN 21 2008/ DISCUSSION... KEY CHALLENGE IN THE IMMEDIATE SHORT TERM WILL BE TEMPS THIS MORNING AND MAX TEMPS DURING THE DAY TODAY. HAVE BEEN CLOUDY ACROSS MOST OF THE FA THROUGHOUT THE NIGHT...WITH THE FAR NORTHERN TIER COUNTIES BEGINNING TO THIN OUT AS OF 3 AM. TEMPS IN THE NORTHERN COUNTIES WILL LIKELY DROP OFF A BIT MORE TONIGHT...BUT DO NOT EXPECT THE REST OF THE AREA TO DROP MORE THAN 3 OR 4 DEG AFT THE CLOUDS CLEAR OUT...THUS STARTING THE DAY OFF MUCH WARMER THAN PREV FORECAST. WARMEST TEMPS TODAY WILL BE IN THE SOUTHWEST...WHERE ABOVE ZERO TEMPS ARE VERY POSSIBLE. NEXT CHALLENGE WILL BE LIGHT SNOW POTENTIAL FOR WAVE MOVING THROUGH TONIGHT. GFS PROGGING SFC TROUGH TO PUSH THROUGH AFT MIDNIGHT...ALTHOUGH NOT A LOT OF MOISTURE WITH IT. NAM CONTINUES TO BE DRY. GOING WITH GFS...INTRODUCED A CHANCE OF LIGHT SNOW MAINLY NORTH OF INTERSTATE 94...WITH NO MORE THAN A COUPLE OF TENTHS OF ACCUMULATION LIKELY. GFS HAS PUSHED FURTHER WEST THE CLIPPER SYSTEM MOVING THROUGH TUE NIGHT. HAVE REDUCED POPS IN THE NORTHEAST AND PARTS OF THE EAST ACCORDINGLY...AND ALSO REDUCED QPFS AND SNOWFALL ACCUMULATIONS AS IT IS BEGINNING TO LOOK LIKE OUR SOUTHWESTERN AND SOUTHERN ZONES WILL ONLY BE BRUSHED. BEYOND TUESDAY...SHOULD SEE A LOT OF SUNSHINE AS RIDGE PUSHES IN FROM WEST LATE IN THE WEEK. INCREASED MAX TEMPS A DEG OR TWO...BUT STILL LOOKING LIKE HIGHS WILL BE PRIMARILY IN THE MID TEENS BY THU. EXPANDED SLIGHT CHANCE OF LIGHT SNOW WEST TO INCLUDE ALL ZONES WITH WAVE PUSHING ACROSS ON FRIDAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG nd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 906 AM CST MON JAN 21 2008 .UPDATE...CURRENT OBS INDICATE FLURRIES UNDER CLOUD COVER ACROSS THE SOUTHERN FA. 12Z NAM/RUC SHOWING WEAK MID-LEVEL FRONTOGENESIS. THIS FORCING WILL SLOWLY SHIFT SE THROUGH THE DAY ALONG WITH CLOUD COVER. 12Z NAM/RUC A BIT SLOWER WITH SHIFTING CLOUD COVER TO THE SE AND WILL ADJUST SKY GRIDS ACCORDINGLY. INTRODUCED FLURRIES. DO NOT HAVE A GOOD HANDLE ON TEMPERATURE FOR TODAY...BUT CURRENT MAXT GRID LOOKS REASONABLE. WILL UPDATE AGAIN IF TEMPS NEED ADJUSTMENT. && .AVIATION...KFAR/KBJI WILL SEE SOME BROKEN SKIES THROUGH A GOOD PORTION OF THE DAY. LIGHT FLURRIES WITH TEMPO VISIBILITIES DOWN TO 5 MILES POSSIBLE. BOTTOM LINE IS PREDOMINANTLY VFR CONDS THROUGH PERIOD. KGFK SHOULD BE MOSTLY CLEAR THROUGH THE DAY. && .PREV DISCUSSION... /ISSUED 359 AM CST MON JAN 21 2008/ DISCUSSION... KEY CHALLENGE IN THE IMMEDIATE SHORT TERM WILL BE TEMPS THIS MORNING AND MAX TEMPS DURING THE DAY TODAY. HAVE BEEN CLOUDY ACROSS MOST OF THE FA THROUGHOUT THE NIGHT...WITH THE FAR NORTHERN TIER COUNTIES BEGINNING TO THIN OUT AS OF 3 AM. TEMPS IN THE NORTHERN COUNTIES WILL LIKELY DROP OFF A BIT MORE TONIGHT...BUT DO NOT EXPECT THE REST OF THE AREA TO DROP MORE THAN 3 OR 4 DEG AFT THE CLOUDS CLEAR OUT...THUS STARTING THE DAY OFF MUCH WARMER THAN PREV FORECAST. WARMEST TEMPS TODAY WILL BE IN THE SOUTHWEST...WHERE ABOVE ZERO TEMPS ARE VERY POSSIBLE. NEXT CHALLENGE WILL BE LIGHT SNOW POTENTIAL FOR WAVE MOVING THROUGH TONIGHT. GFS PROGGING SFC TROUGH TO PUSH THROUGH AFT MIDNIGHT...ALTHOUGH NOT A LOT OF MOISTURE WITH IT. NAM CONTINUES TO BE DRY. GOING WITH GFS...INTRODUCED A CHANCE OF LIGHT SNOW MAINLY NORTH OF INTERSTATE 94...WITH NO MORE THAN A COUPLE OF TENTHS OF ACCUMULATION LIKELY. GFS HAS PUSHED FURTHER WEST THE CLIPPER SYSTEM MOVING THROUGH TUE NIGHT. HAVE REDUCED POPS IN THE NORTHEAST AND PARTS OF THE EAST ACCORDINGLY...AND ALSO REDUCED QPFS AND SNOWFALL ACCUMULATIONS AS IT IS BEGINNING TO LOOK LIKE OUR SOUTHWESTERN AND SOUTHERN ZONES WILL ONLY BE BRUSHED. BEYOND TUESDAY...SHOULD SEE A LOT OF SUNSHINE AS RIDGE PUSHES IN FROM WEST LATE IN THE WEEK. INCREASED MAX TEMPS A DEG OR TWO...BUT STILL LOOKING LIKE HIGHS WILL BE PRIMARILY IN THE MID TEENS BY THU. EXPANDED SLIGHT CHANCE OF LIGHT SNOW WEST TO INCLUDE ALL ZONES WITH WAVE PUSHING ACROSS ON FRIDAY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ TG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO CA 929 AM PST MON JAN 21 2008 UPDATED AVIATION .DISCUSSION...ADVERTISED CHANGE IN THE WEATHER IS UNDERWAY AS SHOWERS CONTINUE TO MOVE ONSHORE IN MOIST CYCLONIC FLOW. SHORT TERM MODELS INCLUDING THE RUC13 ALL SEEM TO BE UNDERESTIMATING QPF IN THE SHORT TERM. LOOKING AT MORNING SATELLITE THERE ARE NUMEROUS SHOWERS OFFSHORE THAT WILL CONTINUE TO ROTATE ONSHORE THROUGH THE DAY...SO IF ANYTHING AREAL COVERAGE SHOULD INCREASE THROUGH THE DAY. SNOW LEVELS LOOKS TO BE AROUND 2500 FEET AT THIS TIME WITH MEASURABLE SNOW REPORTED SO FAR ON TOP OF MOUNT HAMILTON AND IN THE LOS PADRES FOREST OF MONTEREY COUNTY AT 3000 FEET. BODEGA BAY PROFILER ESTIMATES SNOW LEVEL AT 2500 FEET AT THIS TIME. RAWS AT ATLAS PEAK AND BEN LOMOND INDICATE SNOW LEVEL AT THE 2000-2500 FOOT LEVEL. SNOW ADVISORY TO GO INTO EFFECT AT 4 PM FOR THE NORTH BAY HILLS WITH ACCUMULATING SNOW EXPECTED ABOVE 1500 FEET AS QPF FIELD AND COLDER TEMPS COME TOGETHER. WILL HAVE TO AT LEAST CONSIDER HEADLINES FOR OUR OTHER HILL ZONES FOR THIS AFTERNOON AS MODELS SEEM TO BE UNDERDOING QPF AND PERHAPS A BIT HIGH WITH SNOW LEVELS AT THIS TIME. SHOWER ACTIVITY WILL CONTINUE ON TUESDAY BUT SNOW LEVELS WILL RISE AS THE FLOW ALOFT BECOMES MORE SOUTHWEST AS THE UPPER LOW RESPONSIBLE FOR THE PRECIP DRIFTS FURTHER WESTWARD OFFSHORE. SHOWERS AND BELOW NORMAL DAYTIME HIGHS TO CONTINUE THROUGH MOST OF THE WEEK AS THE UPPER LOW STAYS PARKED OFF THE COAST WITH RENEWED SHORTWAVE ENERGY MOVING INTO THE TROUGH THROUGHOUT THE WEEK. THE ECMWF AND GFS SHOW A STRONGER TROUGH BY THURSDAY NIGHT AND FRIDAY WITH MORE WIDESPREAD AND HEAVIER RAIN LIKELY DURING THIS TIME FRAME. WHEN ALL IS SAID AND DONE MANY OF THE COASTAL HILLS WILL END UP WITH A PRETTY WET WEEK AS CONVECTIVE SHOWERS CONTINUE ON AND OFF THROUGH THE PERIOD. SNOW LEVELS WILL OSCILLATE UPWARDS DURING THE MID WEEK TIME FRAME BUT COULD GET BELOW 1500-2000 FEET AGAIN BY SATURDAY AS THE CORE OF THE NEXT TROUGH PASSES OVERHEAD. SOME HINT AT DRYING BY ABOUT THE SECOND HALF OF THE WEEKEND. && .AVIATION...UPDATED TERMINALS TO REFLECT MORE OF A SE FLOW AT THE SFC. HOWEVER...WINDS WILL BE SOMEWHAT PROBLEMATIC TODAY AS WEATHER SYSTEM OFF THE COAST MAY BRIEFLY SWITCH WINDS TO THE SW. OTHERWISE...A SHOWERY REGIME WILL DOMINATE THE REGION WITH SCATTERED SHOWERS AND LOWERED CIGS. SPECIFIC TIMING OF SHOWERS WILL BE HARD AND HAVE USED MOSTLY TEMPOS. BEST CHC FOR SHOWERS WILL BE LATER IN THE DAY AND OVERNIGHT. CONFIDENCE IS MARGINAL. && .MTR WATCHES/WARNINGS/ADVISORIES... 4 PM TDA THROUGH 4 AM TUES...SNOW ADVISORY...N BAY MOUNTAINS. && $$ PUBLIC FORECAST: R WALBRUN AVIATION/MARINE: MEHLE NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SAN FRANCISCO CA 915 AM PST MON JAN 21 2008 .DISCUSSION...ADVERTISED CHANGE IN THE WEATHER IS UNDERWAY AS SHOWERS CONTINUE TO MOVE ONSHORE IN MOIST CYCLONIC FLOW. SHORT TERM MODELS INCLUDING THE RUC13 ALL SEEM TO BE UNDERESTIMATING QPF IN THE SHORT TERM. LOOKING AT MORNING SATELLITE THERE ARE NUMEROUS SHOWERS OFFSHORE THAT WILL CONTINUE TO ROTATE ONSHORE THROUGH THE DAY...SO IF ANYTHING AREAL COVERAGE SHOULD INCREASE THROUGH THE DAY. SNOW LEVELS LOOKS TO BE AROUND 2500 FEET AT THIS TIME WITH MEASURABLE SNOW REPORTED SO FAR ON TOP OF MOUNT HAMILTON AND IN THE LOS PADRES FOREST OF MONTEREY COUNTY AT 3000 FEET. BODEGA BAY PROFILER ESTIMATES SNOW LEVEL AT 2500 FEET AT THIS TIME. RAWS AT ATLAS PEAK AND BEN LOMOND INDICATE SNOW LEVEL AT THE 2000-2500 FOOT LEVEL. SNOW ADVISORY TO GO INTO EFFECT AT 4 PM FOR THE NORTH BAY HILLS WITH ACCUMULATING SNOW EXPECTED ABOVE 1500 FEET AS QPF FIELD AND COLDER TEMPS COME TOGETHER. WILL HAVE TO AT LEAST CONSIDER HEADLINES FOR OUR OTHER HILL ZONES FOR THIS AFTERNOON AS MODELS SEEM TO BE UNDERDOING QPF AND PERHAPS A BIT HIGH WITH SNOW LEVELS AT THIS TIME. SHOWER ACTIVITY WILL CONTINUE ON TUESDAY BUT SNOW LEVELS WILL RISE AS THE FLOW ALOFT BECOMES MORE SOUTHWEST AS THE UPPER LOW RESPONSIBLE FOR THE PRECIP DRIFTS FURTHER WESTWARD OFFSHORE. SHOWERS AND BELOW NORMAL DAYTIME HIGHS TO CONTINUE THROUGH MOST OF THE WEEK AS THE UPPER LOW STAYS PARKED OFF THE COAST WITH RENEWED SHORTWAVE ENERGY MOVING INTO THE TROUGH THROUGHOUT THE WEEK. THE ECMWF AND GFS SHOW A STRONGER TROUGH BY THURSDAY NIGHT AND FRIDAY WITH MORE WIDESPREAD AND HEAVIER RAIN LIKELY DURING THIS TIME FRAME. WHEN ALL IS SAID AND DONE MANY OF THE COASTAL HILLS WILL END UP WITH A PRETTY WET WEEK AS CONVECTIVE SHOWERS CONTINUE ON AND OFF THROUGH THE PERIOD. SNOW LEVELS WILL OSCILLATE UPWARDS DURING THE MID WEEK TIME FRAME BUT COULD GET BELOW 1500-2000 FEET AGAIN BY SATURDAY AS THE CORE OF THE NEXT TROUGH PASSES OVERHEAD. SOME HINT AT DRYING BY ABOUT THE SECOND HALF OF THE WEEKEND. && .AVIATION...SCATTERED SHOWERS ARE EXPECTED AT ALL TERMINALS TODAY WITH VARIABLE CIGS AROUND 3000 FT. WINDS ARE EXPECTED TO BE LIGHT WESTERLY. && .MTR WATCHES/WARNINGS/ADVISORIES... 4 PM TDA THROUGH 4 AM TUES...SNOW ADVISORY...N BAY MOUNTAINS. && $$ PUBLIC FORECAST: R WALBRUN AVIATION/MARINE: ANDERSON/MEHLE NWS ON THE WEB AT WEATHER.GOV/SANFRANCISCO ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1157 AM CST MON JAN 21 2008 .DISCUSSION... ISSUED 1115 AM CST MON JAN 21 2008 UPDATED THE FORECAST TODAY TO ADJUST SKY COVER WITH MORE SUNSHINE SE OF THE IL RIVER LATE THIS MORNING AND INCREASING CLOUDS DURING THE AFTERNOON. CONTINUED 20 TO 30 CHANCE OF LIGHT SNOW LATE THIS AFTERNOON NW OF THE IL RIVER. INCREASED SSE WINDS TODAY TO BREEZY LEVELS FROM 15 TO 25 MPH. HIGHS GET CLOSER TO NORMAL TODAY IN THE UPPER 20S FROM I-74 NE AND 30 TO 35F SW OF I-74. 17Z/11 AM SURFACE ANALYSIS SHOWS 1045 MB MODIFIED ARCTIC HIGH PRESSURE OVER THE MID ATLANTIC STATES BY VA/NC. A 1020 MB LOW PRESSURE WAS OVER NORTH CENTRAL KS WITH IS WARM FRONT EXTENDING OVER FAR SE IA INTO NORTHERN IL JUST NORTH OF GALESBURG...LACON AND KANKAKEE. AREA OF LIGHT SNOW AND FLURRIES NORTH OF THIS WARM FRONT...NORTH OF I-88 IN FAR NORTHERN IL THIS MORNING AND OVER CENTRAL AND NORTHERN IA. INCREASING PRESSURE GRADIENT OVER CENTRAL IL DURING THIS MORNING INCREASING SSE WINDS TO BREEZY LEVELS FROM 15 TO 25 MPH. BROKEN MID LEVEL CLOUDS ALONG AND NW OF THE IL RIVER WHILE SUNNY SKIES ALONG AND SE OF I-55. TEMPS HAVE MODIFIED INTO THE LOW TO MID 20S. DEWPOINTS REMAIN QUITE LOW IN THE SINGLE DIGITS REFLECTING VERY DRY LOWER LEVELS OVER CENTRAL/SE IL. RUC AND WRF MODELS KEEP CENTRAL IL DRY THROUGH 00Z/6 PM...WITH QPF/LIGHT SNOW STAYING NW OF GALESBURG AS LOW PRESSURE OVER NORTH CENTRAL KS MOVES INTO NORTH CENTRAL MO. BUT SHEF MODEL BRINGS SOME LIGHT QPF/LIGHT SNOW INTO KNOX AND STARK COUNTY BETWEEN 21Z AND 00Z (3 TO 6 PM). DECIDED TO HOLD ONTO 20 TO 30 CHANCE OF LIGHT SNOW NW OF THE IL RIVER BUT DURING LATE AFTERNOON. MID AND EVENTUALLY LOW CLOUDS WILL INCREASE FROM THE WEST DURING THE AFTERNOON...WITH SE IL ENJOYING THE MOST SUNSHINE TODAY. LOW PRESSURE TO MOVE ACROSS NORTHERN IL OVERNIGHT SPREADING LIGHT SNOW ACROSS THE STATE TONIGHT WITH 1 TO 2 INCHES LIKELY. BREEZY SSE WINDS 15 TO 25 MPH COMBINED WITH SOME SUNSHINE ESPECIALLY FROM I-55 SE WILL BUMP HIGHS CLOSER TO NORMAL THIS AFTERNOON. HIGHS RANGE FROM THE UPPER 20S FROM I-74 NE AND 30 TO 35F SW OF I-74...WITH FAR SW AREAS FROM WINCHESTER TO LAWRENCEVILLE APPROACHING 35F. HUETTL && .AVIATION... ISSUED 1155 AM CST MON JAN 21 2008 VFR CONDITIONS THIS AFTERNOON WILL DETERIORATE TONIGHT ESPECIALLY BY LATE EVENING INTO OVERNIGHT AS LIGHT SNOW DEVELOPS ACROSS CENTRAL IL. THIS IN RESPONSE TO 1021 MB LOW PRESSURE OVER NE KS DEEPENING AS IT TRACKS NE ACROSS NORTHERN IL OVERNIGHT. LOW DEEPENS TO 1008 MB JUST EAST OF GEORGIAN BAY CANADA BY 18Z/TUE WHILE SWINGING A COLD FRONT THROUGH IL EARLY TUE MORNING. MID LEVEL CLOUDS FROM 6 TO 10K FT FROM THE IL RIVER VALLEY TO SPREAD EAST ACROSS CENTRAL IL DURING THIS AFTERNOON. LOW CLOUDS OF 3 TO 5K FT OVER CENTRAL MO TO SPREAD EAST ACROSS CENTRAL IL EARLY THIS EVENING AFTER SUNSET. LOW CLOUDS OF 1 TO 2K FT WILL MOVE IN FROM 04Z TO 07Z AS LIGHT SNOW DEVELOPS AND REDUCES VISIBILITIES TO 1 TO 3 MILES. IFR TO LIFR CIELINGS AND VSBYS WILL BE POSSIBLE OVERNIGHT FROM 06Z TO 12Z WITH HEAVIER SNOW SHOWERS ESPECIALLY AT PIA AND BMI. BREEZY SSE WINDS THIS AFTERNOON WITH GUSTS OF 18 TO 24KTS TO TURN SSW TONIGHT AROUND 15 KTS AND THEN WEST BEHIND THE COLD FRONT EARLY TUE MORNING WITH GUSTS AROUND 20 KTS. HUETTL && .PREV DISCUSSION... ISSUED 306 AM CST MON JAN 21 2008 SHORT TERM...TODAY THROUGH WEDNESDAY. SFC RIDGE AXIS HAS SHIFTED JUST NORTHEAST OF THE AREA THIS MORNING... AND AS EXPECTED... LOW LEVEL WARM ADVECTION HAS RESULTED IN A SLOW BUT STEADY INCREASE IN MID-LEVEL CLOUD COVER OVERNIGHT ACROSS MUCH OF THE NORTHERN HALF OF THE CWA... WHICH HAS ALLOWED TEMPERATURES TO REMAIN COMPARATIVELY MILD COMPARED TO THE LAST COUPLE OF MORNINGS. LIGHT SNOW ACTIVITY HAS REMAINED NORTH OF THE AREA OVERNIGHT AS EXPECTED... WITH THE STEEPEST ISENTROPIC ASCENT FOCUSED WELL TO OUR WEST. EVEN SO... WEAK RADAR RETURNS SUGGEST A FEW FLURRIES WILL BE POSSIBLE EARLY THIS MORNING NORTH AND WEST OF THE ILLINOIS RIVER... BUT LITTLE ELSE. FORECAST IN THE NEAR TERM HAS BEEN REMARKABLY WELL BEHAVED OVER THE PAST FEW DAYS... AND THERE IS STILL LITTLE CHANGE IN THE FORECAST PHILOSOPHY THROUGH WEDNESDAY. LOW LEVEL WARM ADVECTION TODAY WILL BRING A BRIEF RESPITE FROM THE BITTER COLD AIRMASS THAT SETTLED IN ACROSS THE AREA THIS PAST WEEKEND... BUT WEAK SFC WAVE AND ATTENDANT COLD FRONT WILL MOVE ACROSS THE AREA TONIGHT...BRINGING A BRIEF PERIOD OF LIGHT SNOW TO MOST AREAS OF THE CWA...AND DRAGGING THE COLDER AIR BACK IN BEHIND IT. SYSTEM TONIGHT CONTINUES TO LOOK LOOSELY ORGANIZED AND RELATIVELY PROGRESSIVE... WITH WEAK LIFT PROGRESSING WEST TO EAST FROM THIS EVENING INTO TUESDAY MORNING. LACK OF MID-LEVEL MOISTURE AND ANY REALLY STRONG LIFT WILL HELP KEEP QPF AMOUNTS DOWN... AND AS HAS BEEN MENTIONED THE PAST COUPLE OF DAYS... THERE REALLY IS NO STANDOUT AREA WITH HIGHER SNOWFALL POTENTIAL OVER ANY OTHER. OVERALL... EXPECT ANYWHERE FROM A HALF INCH TO 2 INCHES OF SNOW WITH A GENERAL NORTHWEST-SOUTHEAST GRADIENT. HIGHER AMOUNTS NORTHWEST OF THE SFC WAVE TRACK... I.E. NORTHWEST OF THE ILLINOIS VALLEY. FORECAST SOUNDINGS EARLIER LOOKED SOMEWHAT MARGINAL FOR KEEPING ICE CRYSTALS IN THE CLOUD LAYER BEYOND MIDNIGHT ACROSS WESTERN AND SOUTHERN SECTIONS... BUT IT APPEARS NOW WE SHOULD REMAIN SATURATED UP TO ABOUT THE -10C LEVEL... WHICH REMAINS A LITTLE MARGINAL. CONSIDERING THE LACK OF STRONG LIFT AS WELL... WILL KEEP IN A MENTION OF PATCHY FREEZING DRIZZLE AFTER MIDNIGHT IN THE SOUTHWEST CORNER OF THE CWA... ALTHOUGH THIS IS NOT EXPECTED TO BE A MAJOR HAZARD. LIGHT SNOW PACK...PRESUMABLY MOST PREVALENT IN THE NORTHWEST...WILL LEAD TO ANOTHER FRIGID MORNING ON WEDNESDAY... WITH BELOW ZERO READINGS POSSIBLE AGAIN. CLIPPER SYSTEM APPROACHES WEDNESDAY AFTERNOON... STILL LOOKING FAIRLY WEAK AND VERY PROGRESSIVE...WITH NO MAJOR SNOW ACCUMULATIONS EXPECTED WITH IT AT THIS TIME. LONG TERM...THURSDAY THROUGH SUNDAY. PATTERN WILL SHIFT BY THE END OF THE WORKWEEK AS THE TROUGH THAT HAS BEEN CARVED OUT ACROSS THE NORTHEASTERN CORNER OF THE CONTINENT FINALLY BREAKS DOWN... RESULTING IN A MORE PROGRESSIVE AND MILDER PATTERN HEADING INTO THE WEEKEND. MODELS HAVE BEEN HAVING SOME PROBLEMS WITH THE HANDLING OF A DEEPENING TROUGH OFF THE WEST COAST BEYOND THE DAY 4 TIMEFRAME... AND THIS HAS EVENTUAL IMPACTS ON OUR WEATHER HEADING TOWARDS THE END OF THE WEEKEND...DEPENDING ON THE EVOLUTION AND POSSIBLE EASTWARD EJECTION OF THE WEST COAST TROUGH. HOWEVER... THIS DOES NOT APPEAR TO HAVE MUCH IMPACT IN THE DAYS 1-5 TIMEFRAME. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION...UPDATE NATIONAL WEATHER SERVICE MARQUETTE MI 1223 PM EST MON JAN 21 2008 UPDATED FOR 18Z TAF DISCUSSION .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS CONTINUES TO SHOW AN AMPLIFIED PATTERN ACROSS NORTH AMERICA...WITH STRONG RIDGING FROM THE EAST PACIFIC INTO NW CANADA...TROUGHING OVER THE PACIFIC NW... AND A BROAD UPPER TROUGH OVER THE EAST HALF OF CANADA. NW UPPER FLOW WHICH HAS BEEN OVER UPPER MI THE PAST FEW DAYS IS TURNING MORE WESTERLY...DUE TO THE COMBINATION OF THE DIGGING PACIFIC NW TROUGH AND A SHRTWV DROPPING SOUTH INTO SOUTHERN SASKATCHEWAN. THIS WESTERLY FLOW IS GRADUALLY BRINGING WARMER AIR INTO UPPER MI AS NOTED BY 850MB TEMP RISES OF 4C AT MPX AND INL BETWEEN 12Z AND 00Z. HOWEVER...THE AIRMASS STILL REMAINS COLD...GIVEN THE -24C READING AT INL AND -19C AT MPX. THUS...LAKE EFFECT CONTINUES OFF LAKE SUPERIOR. HOWEVER...THE BANDS ARE BECOMING MORE EAST-WEST ORIENTED THANKS TO THE UPPER LEVEL HEIGHT RISES SUPPORTING MORE WESTERLY LOW LEVEL FLOW...IN ADDITION TO LAND BREEZES WHICH HAVE DEVELOPED. TEMPS INLAND HAVE DROPPED INTO THE TEENS BELOW ZERO...BUT HAVE NOT DROPPED MUCH MORE DUE TO INCREASING HIGH CLOUDS IN THE UPPER FLOW. TO THE WEST...A FAIRLY POTENT SHRTWV CAN BE SEEN CROSSING NEVADA. DOWNSLOPING WESTERLY FLOW AHEAD OF THIS SHRTWV HAS CAUSED PRESSURE FALLS IN THE TEXAS PANHANDLE. FROM THE DEVELOPING LOW PRESSURE...A WARM FRONT EXTENDS NE INTO SW IOWA. && .DISCUSSION... MAIN FORECAST CONCERN IS SNOWFALL OVER THE KEWEENAW THROUGH TONIGHT. TODAY...SHRTWV OVER NEVADA WILL HEAD OUT INTO THE CENTRAL PLAINS... CAUSING THE TEXAS PANHANDLE LOW TO LIFT UP TOWARDS KANSAS CITY. MEANWHILE TO OUR NW...THE SHRTWV TROUGH OVER SOUTHERN SASKATCHEWAN IS PROGGED TO DROP DOWN INTO NORTH DAKOTA AND NW MN. THE COMBINATION OF BOTH FEATURES WILL RESULT IN THE UPPER FLOW TURNING SW...MORE FAVORABLE FOR BRINGING WARMER AIR INTO THE CWA. IN FACT...MODELS BRING 850MB TEMPS UP ABOUT 4C FROM CURRENT READINGS. THIS MAY NOT SEEM LIKE A WHOLE LOT...BUT IT SHOULD PRODUCE A MORE FAVORABLE ENVIRONMENT FOR DENDRITES COMPARED TO THE RECENT SMALLER SNOWFLAKES. THIS WILL PLAY A ROLE IN TWO DIFFERENT AREAS OF CONCERN. THE FIRST CONCERN IS THE POSSIBILITY OF SYNOPTIC PCPN WITH THE LOW LIFTING UP TOWARDS KANSAS CITY. MODELS DEPICT MID-LEVEL FRONTOGENESIS INCREASING OVER CENTRAL WI INTO NORTHERN LOWER MI DURING THE AFTN. GIVEN THE LOCATION OF THIS AXIS...AND THE PRESENCE OF A 120-130 JET STRETCHING FROM UPPER MI EASTWARD...FAVORING UPPER DIVERGENCE SOUTH OF THE CWA...THINK MUCH OF THE PCPN SHOULD STAY TO THE SOUTH. DRY AIR PRESENT OVER THE CWA AS INDICATED BY THE 00Z INL AND GRB SOUNDINGS SHOULD ALSO HOLD SYNOPTIC PCPN FROM MARCHING NORTH. WILL MAINTAIN CHANCE POPS...BUT RESTRICT THEM JUST TO THE SOUTH CENTRAL. THE OTHER PCPN CONCERN IS LAKE EFFECT SNOW. FOR THE EASTERN CWA...SOME LAKE EFFECT MIGHT LINGER FOR A FEW MORE HOURS PAST THE END TIME OF THE ADVISORY...BUT SEE NO NEED TO EXTEND THE ADVISORY AT THE PRESENT TIME. OVER THE KEWEENAW...LOW LEVEL WINDS ARE PROGGED TO BACK A LITTLE MORE SW THAN PREVIOUSLY THOUGHT...WHICH COULD MOVE THE CURRENT LAKE EFFECT COMPLETELY OFFSHORE FOR SOME OF THE KEWEENAW THIS AFTERNOON. THIS IS INDICATED BY THE NAM/GFS/LOCAL WRF-ARW RUN. HOWEVER...THE LOCAL WRF-ARW RUN DOES MANAGE TO BRING A CONVERGENT BAND BACK INTO THE KEWEENAW AFTER 20Z. FEEL THIS SOLUTION MIGHT BE THE BEST TO FOLLOW AS IT USUALLY HAS A BETTER HANDLE ON THE LAKE AGGREGATE. SOUNDINGS DEPICT AT LEAST SOME DENDRITIC GROWTH BETWEEN THE CLOUD BASE AND 850MB...WHICH MEANS WHEN THE CONVERGENT BAND MOVES IN...THERE COULD BE SOME DECENT SNOWFALL RATES. THEREFORE...HAVE LEFT THE GOING ADVISORY INTACT. GIVEN WARMER AIR MOVING IN...WARMER TEMPS ARE EXPECTED TODAY. ONLY MADE MINOR ADJUSTMENTS TO HIGHS. TONIGHT...SHRTWV TROUGH OVER NORTH DAKOTA IS PROGGED TO SHIFT EAST TOWARDS WESTERN LAKE SUPERIOR BY 12Z TUE. THIS TROUGH SHOULD HELP PROMOTE A RAPID PROGRESSION OF THE SHRTWV LIFTING UP FROM THE CENTRAL PLAINS...AND FAVOR THE GFS/UKMET IDEA OF BRINGING THE SHRTWV INTO LOWER MI BY 12Z WITH A WEAKER SFC LOW SITUATED NEAR ALPENA AT THE SAME TIME. THIS IS ALSO FAVORED BY HPC. MID-LEVEL FRONTOGENESIS AND UPPER DIVERGENCE FIELDS FROM THE GFS STILL SUGGEST THE BEST FORCING FOR PCPN TO REMAIN TO THE SOUTH...THOUGH ENOUGH CONFIDENCE EXISTS TO RAISE POPS TO LIKELY IN SOUTHERN MNM COUNTY. THE REST OF THE CWA WILL HAVE LOW CHANCE POPS...AND BOTH AREAS ARE FOR MAINLY IN THE EVENING AS THE MAIN MID-LEVEL FRONTOGENESIS AREA SHIFTS EAST AFTER 06Z. NEXT CONCERN IS WITH THE SHRTWV TROUGH...AS 850MB TEMPS FALL 1-2C. LOW LEVEL FLOW TURNS MORE WESTERLY IN THE EVENING...SO THE LAKE EFFECT BAND ENTERING THE KEWEENAW THIS AFTERNOON SHOULD REMAIN FAIRLY PROGRESSIVE...STALLING OUT AND WEAKENING OVER ONTONAGON COUNTY LATER IN THE NIGHT. HAVE EXTENDED THE ADVISORY FOR THE KEWEENAW TO 06Z TONIGHT TO ACCOUNT FOR THE LAKE EFFECT BAND. TO THE EAST...THE SWITCH TO MORE WEST TO EVEN NW WILL BRING THE EASTERN EXTENT OF THE BAND DOWN INTO LUCE/ALGER COUNTIES...FOLLOWED BY THE TYPICAL ONTARIO LAND BREEZE CONVERGENT BAND FROM NE LAKE SUPERIOR INTO LUCE COUNTY. THE REST OF THE CWA SHOULD SEE SOME CLEARING DURING THE OVERNIGHT HOURS TO ALLOW TEMPS TO FALL. WILL TREND TEMPS DOWNWARD GIVEN THIS CLEARING POSSIBILITY AND A DRY AIRMASS IN PLACE. TUE...SHRTWV TROUGH SWINGS INTO UPPER MI. WITH THIS TROUGH COMES ANOTHER COOL BLAST OF AIR...WITH 850MB TEMPS OF -24 TO -26C ENTERING WESTERN LAKE SUPERIOR BY 00Z WED. THUS...MORE LAKE EFFECT IS EXPECTED. SURFACE PATTERN SHOWS LAKE INDUCED TROUGHING SETTING UP...WITH LOW PRESSURE NEAR WHITEFISH POINT AND A TROUGH EXTENDING WEST THROUGH TWIN LAKES. THE HEAVIEST LAKE EFFECT SNOW...WHICH WILL NOT BE ALL THAT HEAVY GIVEN THE COLD AIR MOVING IN REDUCING SNOW TO WATER RATIOS...WILL BE CONFINED TO THE TROUGH AS IT PROVIDES A SOURCE OF CONVERGENCE. THUS...AGAIN THE WESTERN U.P. AND THE AREA FROM ALGER INTO NORTHERN LUCE COUNTY IS EXPECTED TO BE UNDER THE GUN FOR SNOW. DRY WEATHER IS EXPECTED FOR THE REST OF THE CWA...WITH TEMPS FAIRLY SIMILAR TO THOSE ON MON. TEMPS COULD FALL LATE IN THE DAY AS THE COLDER AIR MOVES IN. TUE NIGHT INTO WED...SHRTWV TROUGH HEADS OFF TOWARDS QUEBEC TUE NIGHT WHILE ANOTHER SHRTWV TROUGH DROPS SOUTH THROUGH SOUTH CENTRAL CANADA. THIS SECOND SHRTWV TROUGH...WITH A LITTLE MORE OF A COLD AIR PUNCH...SHOULD ENTER UPPER MI DURING THE DAY WED. THUS...CONTINUED LAKE EFFECT WITH CONTINUED BELOW NORMAL TEMPERATURES ARE EXPECTED. WIND FLOW DOES TURN A BIT MORE NORTHERLY WITH THE SECOND SHRTWV TROUGH WEDNESDAY MORNING...WHICH MEANS MARQUETTE AND WESTERN ALGER COUNTIES MAY PICK UP SOME SNOW. HOWEVER...THE MORE NORTHERLY WINDS DO NOT LAST LONG...AS MODELS SHOW ANY LAKE EFFECT BANDS HEADING OFF TOWARDS EASTERN ALGER COUNTY LATER WED AFTERNOON. EITHER WAY...IT STILL LOOKS LIKELY THAT ALL OF THE WESTERN COUNTIES WILL PICK UP MORE SNOW...THOUGH AGAIN WITH THE COLD 850MB TEMPS (DROPPING TO AROUND -26C BY 18Z WED) SUGGESTS FINER SNOWFLAKES. ONLY MINOR TWEAKS WERE MADE TO THE GOING LOW AND HIGH TEMPS. WED NIGHT INTO THU...THE PATTERN STARTS TO CHANGE DURING THIS PERIOD...AS THE SHRTWV TROUGH OVER THE CWA DIGS DOWN TOWARDS THE OHIO VALLEY AND THE CURRENT EAST PACIFIC RIDGE GETS PUSHED EASTWARD TOWARDS THE CWA. HOWEVER...850MB TEMPS EVEN AT 18Z THU ARE STILL DEPICTED BELOW -18C. NOT UNTIL 00Z DO 850MB TEMPS START TO GET WARM ENOUGH OVER WESTERN LAKE SUPERIOR TO ALLOW LAKE EFFECT TO END (-8 TO -10C) THUS...WITH WNW WINDS THROUGH THIS PERIOD...MORE LAKE EFFECT SNOW IS EXPECTED FOR THE WESTERN U.P. AND ALGER INTO NORTHERN LUCE COUNTIES. TEMPS COULD GET QUITE CHILLY WED NIGHT IF SKIES CAN CLEAR...AS NOTED BY MEX COOP GUIDANCE OF -20F AT CHAMPION. ALTHOUGH WE ARE WARM ADVECTING ON THU...TEMPS WILL STRUGGLE TO GET MUCH HIGHER THAN THE LOW TEENS...IF EVEN 10 ABOVE IN INLAND LOCATIONS. BEYOND THU...THE EAST PACIFIC RIDGE BUILDS INTO THE CWA FOR FRI...CAUSING 850MB TEMPS TO CLIMB TO PERHAPS AS HIGH AS -4C. MEX GUIDANCE RESPONDS ACCORDINGLY BY SHOWING HIGH TEMPS IN THE MID 20S. GIVEN THE GOOD AGREEMENT WITH THE 00Z ECMWF...HAVE RAISED HIGHS A FEW DEGREES. NO OTHER CHANGES MADE BEYOND FRIDAY. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... LAKE EFFECT SNOW HAS TEMPORARILY ENDED AT KCMX AS WINDS ARE SW AND WILL KEEP BANDS OFFSHORE AND THIS SHOULD CONTINUE TO BRING VFR CONDITIONS INTO THE AFTERNOON. WINDS BECOME WESTERLY THIS EVENING...SO IFR CONDITIONS RETURN THROUGH TONIGHT INTO TUE MORNING AT KCMX. VFR CONDITIONS EXPECTED AT KSAW THROUGH THE PERIOD EXCEPT COULD GO MVFR WITH LIGHT SNOW LATE THIS AFTERNOON THROUGH THIS EVENING ON THE NORTHERN FRINGE OF THE SYSTEM PASSING TO THE SOUTH. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WEST TO NORTHWEST WINDS IN THE 15 TO 30 KT RANGE WILL GRADUALLY BACK TO SOUTHWEST OR WEST AS A TIGHT GRADIENT PERSISTS BETWEEN ARCTIC HIGH PRESSURE BUILDING SOUTHEAST FROM THE PLAINS AND A LINGERING TROUGH INTO THE UPPER GREAT LAKES. LOW PRESSURE WILL MOVE FAR ENOUGH SOUTH OF THE AREA SO THAT LAKE INDUCED TROUGHING TONIGHT INTO TUE WILL KEEP MAINLY W OR WSW WINDS GOING OVER THE SOUTH PORTION OF THE LAKE AND NW WINDS OVER THE NORTH HALF WITH WIND VALUES MAINLY IN THE 15 TO 25 KT RANGE. A COLD FRONT WILL MOVE THROUGH TUESDAY NIGHT WITH WINDS VEERING NORTHERLY BY WED. HEAVY FREEZING SPRAY WILL CONTINUE THIS MORNING DUE TO THE STRONG WINDS AND VERY COLD ARCTIC AIR. HEAVY FREEZING SPRAY WILL AGAIN DEVELOP TUESDAY NIGHT INTO WEDNESDAY AS A REINFORCING BATCH OF ARCTIC AIR AND STRONGER WINDS MOVES IN. && .MQT WATCHES/WARNINGS/ADVISORIES... MICHIGAN... LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 1 AM EST TUESDAY FOR MIZ001-003. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ002. LAKE EFFECT SNOW AND BLOWING SNOW ADVISORY UNTIL 5 AM EST EARLY THIS MORNING FOR MIZ006-007. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LSZ162-263>267. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ248-250. && $$ SYNOPSIS/DISCUSSION...AJ AVIATION...MICHELS MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 308 PM CST MON JAN 21 2008 .DISCUSSION... INTERESTING SNOW EVENT UNFOLDING ACROSS THE SOUTHERN AND SOUTHEASTERN SECTIONS OF THE FORECAST AREA TODAY...AND MAIN FORECAST CONCERN REVOLVES AROUND HOW IT WILL EVOLVE OVER THE REST OF THE AFTERNOON AND INTO THE EVENING HOURS. WIDESPREAD AREA OF APPROXIMATELY 2 INCH SNOW AMOUNTS HAVE BEEN RECEIVED FROM SPOTTERS THIS AFTERNOON...TO THE SOUTH OF AN OWATONNA TO SAINT JAMES LINE. MORE LOCALIZED AREA OF 3 TO 4 INCH AMOUNTS SEEN IN FARIBAULT...FREEBORN...AND STEELE COUNTIES...ASSOCIATED WITH HIGH REFLECTIVITY BAND THAT MOVED NORTHWARD INTO SOUTHERN MINNESOTA AND STRENGTHENED UPON DOING SO. NAILING DOWN SNOW AMOUNTS HAS BEEN QUITE TRICKY...WITH HIGHER REFLECTIVITIES ASSOCIATED WITH LARGE FLAKES...WITH SMALL GRANULAR PRECIPITATION PARTICLES IN THE LOWER REFLECTIVITIES. RADAR TRENDS HAVE SHOWN THAT THIS WARM ADVECTION INDUCED HIGHER REFLECTIVITY BAND IS SHIFTING MORE INTO SOUTHEAST MINNESOTA/SOUTHWEST WISCONSIN...SO ADDITIONAL RAPID ACCUMULATION IS NOT EXPECTED. RUC/NAM FORECASTS...COMBINED WITH RADAR SIGNALS...INDICATE THAT DEFORMATION/MID LEVEL FRONTOGENESIS IS TAKING OVER AS THE MAIN FORCING MECHANISM...LIKELY RESULTING IN SMALLER GRAINS/FLAKES. SOME CONTEMPLATION OCCURRED REGARDING A POSSIBLE UPGRADE TO A HEAVY SNOW WARNING FOR A SMALL PORTION OF SOUTH CENTRAL MINNESOTA /OWATONNA TO ALBERT LEA/...WHERE FRONTOGENESIS AND RELATED OMEGA PROGS SHOW THE MOST FAVORABLE LOCATIONS FOR ADDITIONAL ACCUMULATION...ABOVE WHAT HAS FALLEN AND WILL CONTINUE TO FALL FOR THE REMAINDER OF THIS AFTERNOON. WITH SMALLER SNOWFALL RATES EXPECTED...AS DISCUSSED ABOVE...COORDINATION WITH DMX AND ARX SOLIDIFIED THE INITIAL LEANINGS TO STAYING WITH THE ADVISORY. IT WILL BE CLOSE...HOWEVER. SNOW SHOULD LARGELY TAPER BY MIDNIGHT...AS THE SURFACE LOW SHIFTS INTO NORTHWESTERN ILLINOIS...CONTINUING ITS EASTWARD PUSH. NEXT ISSUES TONIGHT ARE TEMPERATURES AND RESULTANT WIND CHILLS. WE SHOULD SEE SOME BREAKS IN THE CLOUDS...AND WITH MUCH LOWER DEW POINTS/TEMPERATURES UPSTREAM...TEMPERATURES SHOULD DO SOME BOTTOMING OUT OVER THE NORTHERN PART OF THE FORECAST AREA...ESPECIALLY IN THE AXN/LXL REGION. LOW LEVEL WARM ADVECTION IN ADVANCE OF THE NEXT CLIPPER SYSTEM WILL QUICKLY ENSUE LATE TONIGHT...LEADING TO A RISE IN TEMPERATURES AFTER MIDNIGHT. WINDS WILL BE AROUND 10 MPH FOR MUCH OF THE NIGHT...AND WITH CURRENTLY FORECAST HOURLY TEMPERATURES...PARTS OF THE AREA DO REACH WIND CHILL ADVISORY CRITERIA FOR A COUPLE OF HOURS BEFORE RISING. WITH A LITTLE UNCERTAINTY AS TO HOW LOW THE TEMPERATURES WILL DROP BEFORE ONSET OF THE RISE...WE HAVE ELECTED TO HOLD OFF ON AN ADVISORY FOR THE TIME BEING. WILL PASS ALONG CONCERN TO THE EVENING SHIFT HOWEVER. AFOREMENTIONED CLIPPER SYSTEM IS TAKING A MORE SOUTHWESTERLY TRACK THAN PREVIOUS FORECASTS...SO WE HAVE REMOVED THE SNOW CHANCES FOR THE FORECAST AREA FOR TOMORROW NIGHT AND WEDNESDAY...FAVORING A SCATTERED FLURRY MENTION INSTEAD. TEMPERATURES TAKE ANOTHER TUMBLE ON THE BACKSIDE OF THE TROUGH...WITH WELL BELOW ZERO LOWS FORECAST FOR THURSDAY MORNING...AS ARCTIC HIGH SINKS THROUGH THE UPPER MIDWEST. WOULD NOT BE SURPRISED TO SEE SOME 20 BELOW READINGS ALONG THE I-90 CORRIDOR...WHERE THE FRESH SNOW HAS FALLEN AND THE HIGH WILL BE IN CLOSEST PROXIMITY. WE QUICKLY MAKE A RETURN TO WARMER AIR TOWARD THE WEEKEND...WITH HIGHS ACTUALLY APPROACHING FREEZING FOR THE FIRST TIME SINCE THE BEGINNING OF THE MONTH. PRECIPITATION CHANCES IN THE EXTENDED LOOK TO INCREASE FOR FRIDAY...WITH WARM ADVECTION INCREASING...AND ALSO FOR THE BEGINNING OF NEXT WEEK...WITH DEEP LOW PRESSURE SYSTEM SET TO ORGANIZE AND PUSH THROUGH THE REGION ON SUNDAY NIGHT/MONDAY. QUESTIONS WITH THIS REVOLVE AROUND PRECIP TYPE WITH MODEL DISCREPANCIES ON EXACTLY WHERE THE WARM SECTOR WILL BE LOCATED. && .PREV DISCUSSION... /ISSUED 112 PM CST MON JAN 21 2008/ WE HAVE ADDED A FEW COUNTIES TO OUR SNOW ADVISORY AND EXTENDED THE TIME OF A PORTION OF IT UNTIL 03Z. 25 TO 35 DBZ SNOW BAND HAS DEVELOPED IN EXPECTED FRONTOGENETIC REGION ACROSS SOUTH CENTRAL MINNESOTA...AND IS LIFTING...AS PROGGED...TO THE EAST NORTHEAST. REPORTS FROM SOUTHEAST MINNESOTA INDICATE THAT...UNLIKE BENEATH THE LIGHTER ECHOES...LARGE FLAKES /FINALLY AS EXPECTED/ ARE FALLING AND ACCUMULATING QUITE RAPIDLY. A DECISION ON SOME OF THE WISCONSIN COUNTIES WILL HAVE TO BE MADE FOR REGULAR PACKAGE ISSUANCE TIME...WITH RUC/NAM FORECASTS TAKING THE FRONTOGENETIC AREA VERY NEAR THE DURAND...ELLSWORTH...AND EAU CLAIRE VICINITIES. && .AVIATION.../18Z TAF ISSUANCE/ SNOW CONTINUES ACROSS EAU...MSP...RWF...AND RNH TAF SITES IN RESPONSE TO CONVEYOR BELT OF MOISTURE OVERIDING WARM FRONTAL BOUNDARY ABOVE CENTRAL IOWA. SHORT DURATION VFR CIGS AND VSBYS WILL BE ENCOUNTERED PRIOR TO 00Z AT THESE AIRPORTS. GFS40 ISENTROPIC ANAL MUCH OF THE ACTIVITY WILL END BY 03Z TIME FRAME. 0.5 REFLECTIVELY SIGNATURES INDICATING A DECREASING TREND OF INTENSITY ACROSS FAR SOUTH CENTRAL MN. BEST FRONTOGENTIC FORCING AND DR DENDRITE TEMPERATURES WILL ALSO BE SHOVED SOUTH BY THE EARLY EVENING HOURS...LIMITING ANY APPRECIABLE SNOW AMOUNTS THEREAFTER. VSBYS WILL RETURN TO VFR MODE BY 04Z ALL TAF SITES...WITH MVFR TO VFR CIGS BECOMING THE NORM ALL LOCATIONS ALSO THIS TIME FRAME. ANOTHER FAST MOVING UPPER LEVEL TROUGH WILL BRING A SHORT LIVED DECK OF MVFR CIGS TO ALL MN TAF SITES BY 15Z ON TUE...AND ACROSS WEST CENTRAL WI BY 18Z. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR FREEBORN-GOODHUE- RICE-STEELE-WASECA. SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR FARIBAULT-MARTIN. WI...NONE. && $$ KAT/AJZ mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 112 PM CST MON JAN 21 2008 .UPDATE... UPDATED PUBLIC DISCUSSION. && .DISCUSSION... WE HAVE ADDED A FEW COUNTIES TO OUR SNOW ADVISORY AND EXTENDED THE TIME OF A PORTION OF IT UNTIL 03Z. 25 TO 35 DBZ SNOW BAND HAS DEVELOPED IN EXPECTED FRONTOGENETIC REGION ACROSS SOUTH CENTRAL MINNESOTA...AND IS LIFTING...AS PROGGED...TO THE EAST NORTHEAST. REPORTS FROM SOUTHEAST MINNESOTA INDICATE THAT...UNLIKE BENEATH THE LIGHTER ECHOES...LARGE FLAKES /FINALLY AS EXPECTED/ ARE FALLING AND ACCUMULATING QUITE RAPIDLY. A DECISION ON SOME OF THE WISCONSIN COUNTIES WILL HAVE TO BE MADE FOR REGULAR PACKAGE ISSUANCE TIME...WITH RUC/NAM FORECASTS TAKING THE FRONTOGENETIC AREA VERY NEAR THE DURAND...ELLSWORTH...AND EAU CLAIRE VICINITIES. && .AVIATION.../12Z TAF ISSUANCE/ LIGHT SNOW LOOKS TO MAKE IT TO ALL TAF SITES TODAY...WITH SOME CHANCES OF IFR CONDITIONS AT RWF...MSP...AND WI TAF SITES. EARLY LOOK AT 12Z MPX RAOB DATA SHOWS MOISTENING DOWN TO 3100 FT AS ARCTIC MASS HAS RAPIDLY MOISTENED WITH PACIFIC MOISTURE FEEDING INTO OUR ONCE VERY DRY AIR MASS. UPPER SUPPORT IS INCREASING AND WIND PROFILERS FROM UPSTREAM /SRN TO CTRL PLAINS/ ARE SHOWING A RESPONSE WITH A 65 KT MORNING LOW LEVEL JET IN THE SRN TO CTRL PLAINS POINTED INTO IA AND SRN MN. SO EXPECT CIGS TO CONTINUE TO LOWER THROUGH THE MORNING WITH SNOW EVENTUALLY MAKING IT DOWN. AS SYSTEM TO OUR SOUTH SORT OF REDEFINES ITSELF...AREA BECOMES UNDER MORE DEFORMATION THAN WARM AIR ADVECTION BY MID AFTN...NAMELY EAU. SO KEEP SNOW PREDOMINANT AT MOST SITES FROM LATE MRNG THRU AFTN AND FROM THE GET GO AT RWF. AS THE LOW MOVES INTO WI...A BAGGY LOW LEVEL GRADIENT IS LEFT IN ITS PLACE THIS EVE AND EXPECT MVFR CIGS TO BE WIDESPREAD...SLOWLY BEGINNING TO SCOOT DURING THE OVERNIGHT AS A MORE PROGRESSIVE PATTERN SETS UP INTO MIDWEEK. && .PREV DISCUSSION... /ISSUED 543 AM CST MON JAN 21 2008/ THICKENING CLOUDS HAVE PRETTY MUCH STEADIED TEMPERATURES LAST FEW HOURS WITH SLIGHT RISES IN SW MN WHERE WINDS HAVE GAINED A SOUTHEAST COMPONENT. UPPER WINDS HAVE BACKED ENOUGH IN LAST 12 TO 24 HOURS AS TROUGH SLOWLY DIGS OUT WEST TO ALLOW SOME HIGHER LEVEL MOISTURE TO MOVE INTO AREA. LIMITED MOISTURE HAS KEPT ANY SNOW FROM ACCUMULATING THUS FAR...BUT VISIBILITY BEGINNING TO COME DOWN IN SC MN INTO THE 3-5 MILE RANGE. BEST WARM ADVECTION ABOVE 850 MB AS SYSTEM COMES THRU. BY 12Z WAA AT 700 MB ACTUALLY QUITE STRONG INTO S MN AS 700 MB WINDS INCREASE TO AROUND 30 KT WITH WAA CONTINUING INTO THE EARLY AFTERNOON AROUND FRM AND THRU THE AFTERNOON IN SE MN INTO THE EAU AREA. SWLY FLOW SHOULD CONTINUE LONG ENOUGH TO CONTINUE MOISTENING AND EXPECT VISIBILITIES TO BEGIN TO DROP AND SNOW TO BEGIN ACCUMULATING BETTER BY 12Z. THE 00Z OMA RAOB SHOWED .25 PWATS WHICH SHOULD BE WORKING INTO S MN. SNOW RATIOS WILL BE HIGH IN THE 15 TO 20 TO ONE RANGE GIVEN THE COLD AIRMASS. WILL CONTINUE WITH THE SNOW ADVISORY ACROSS OUR S TIEROF COUNTIES FOR TODAY...BUT THINK AMOUNTS WILL BE A BIT LESS THAN WE HAVE GOING NOW SINCE LITTLE ACCUM HAS OCCURRED IN THE OVERNIGHT. METERS HAVE BEEN SHOWING -SN ACROSS MUCH OF SODAK WITH VISBYS STEADILY DROPPING IN SODAK WITH -SN MOVING INTO W MN. THUS MOVED THE MENTION OF -SN A BIT FARTHER N IN MN. TEMPERATURES WILL BE TRICKY NEXT COUPLE DAYS WITH PUSH/PULL PATTERN AS A COUPLE WEAK SYSTEMS COME THRU WITH WIND SHIFTS AND CLOUDS. A WINDOW OF OPPORTUNITY FOR TEMPS TO DROP TONIGHT AS SURFACE RIDGE MOVES ACROSS AREA...BUT LATE TONIGHT WEST WINDS INCREASE AHEAD OF UPSTREAM COLD FRONT. MAY SEE SOME FLURRIES WITH FRONTAL PASSAGE MAINLY IN CENTRAL MN INTO WI. GFS AND CANADIAN MODEL QUITE SIMILAR ON WEAK CLIPPER MOVING THRU LATE TUES NIGHT/EARLY WED WITH LOW TRACKING ACROSS SODAK INTO E NEBRASKA WHICH WOULD KEEP SNOW CHANCES MAINLY SW OF OUR AREA. STILL LOOKING LIKE A SIGNIFICANT WARMING TREND BRINGING US BACK TO AT LEAST NORMAL TEMPERATURES LATE IN THE WEEK. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...SNOW ADVISORY UNTIL 9 PM CST THIS EVENING FOR FREEBORN-GOODHUE- RICE-STEELE-WASECA. SNOW ADVISORY UNTIL 6 PM CST THIS AFTERNOON FOR FARIBAULT-MARTIN. WI...NONE. && $$ KAT/MTF/BAP mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON MS 300 PM CST MON JAN 21 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT...HIGH PRESSURE CENTERED OVER THE MID ATLANTIC SEABOARD THIS AFTERNOON WAS STILL DOMINATING OVER OUR CWA AND PROVIDING MOSTLY SUNNY SKIES OVER THE EASTERN TWO THIRDS OF OUR CWFA THIS AFTERNOON. TEMPERATURES HAVE REBOUNDED NICELY AFTER A RATHER COLD START AND RISEN INTO THE UPPER 40S AND LOWER 50S. THE SURFACE HIGH WILL CONTINUE TO SHIFT EAST TONIGHT INTO THE ATLANTIC AND ALLOW FOR WEATHER CHANGES FROM THE WEST. WATER VAPOR IMAGERY/RUC ANALYSIS SHOWS A SHORT WAVE OVER COLORADO THAT WILL MOVE EAST TONIGHT AS WELL. AS IT DOES...A SURFACE LOW OVER NORTHWEST NEW MEXICO WILL DEEPEN AND MOVE OFF TO THE NORTHEAST. THIS LOW WILL SEND A TRAILING COLD FRONT THROUGH OUR CWFA TUESDAY. WAA WILL BEGIN INCREASING FROM THE WEST TONIGHT AND BRING US INCREASING RAIN CHANCES. REGIONAL RADARS SHOW LIGHT RAIN ALONG THE INTERSTATE 20 CORRIDOR IN NORTHERN LOUISIANA THAT WILL SHIFT INTO OUR PARISHES THIS EVENING. WHILE THIS IS OCCURRING OUR EASTERN SITES WILL BEGIN TO RAPIDLY COOL. OVERNIGHT LOWS WILL LIKELY OCCUR AT MIDNIGHT AND REMAIN STEADY OR WARM SLIGHTLY AFTER MIDNIGHT. ALL SITES ARE EXPECTED TO REMAIN ABOVE FREEZING AT THE SURFACE BUT FORECAST SOUNDINGS STILL SHOW SOME POTENTIAL FOR LIGHT SLEET MIXED WITH RAIN AT THE ONSET OF RAIN IN OUR NORTHEAST AND EAST COUNTIES. ANY MIXED PRECIPITATION THAT OCCURS SHOULD BE VERY BRIEF AS THE ATMOSPHERE SHOULD WARM RESULTING IN ALL RAIN. THE COLD FRONT IS EXPECTED TO BE ENTERING OUR DELTA COUNTIES BY SUNRISE TUESDAY MORNING AND BE JUST NORTHWEST OF JACKSON BY NOON AND NEAR HATTIESBURG BY SUNSET. THE RAIN SHOULD BE WIDESPREAD TUESDAY OVER MUCH OF OUR AREA...BUT MUCH OF THE RAINFALL WILL BE LIGHT AS PWS ARE ONLY EXPECTED TO POOL NEAR AN INCH AHEAD OF THE FRONT. MODELS ARE STILL INDICATING SOME ELEVATED INSTABILITY AROUND NOON AS THE FRONT MOVES INTO CENTRAL MISSISSIPPI. WL MENTION THUNDER TUESDAY GENERALLY ALONG AND SOUTH OF INTERSTATE 20. THE GFS PROLONGS RAIN TUESDAY NIGHT IN OUR SOUTH DUE TO A WEAK SHORTWAVE MOVING OVER THE AREA BUT HIGH PRESSURE BEHIND THE FRONT WILL BE BUILDING INTO THE AREA AND SHOULD PUSH THE FRONT FAR ENOUGH SOUTH TO END RAIN CHANCES SHORTLY AFTER MIDNIGHT. WEDNESDAY MORNING LOWS WILL BE BACK DOWN TO FREEZING IN THE NORTH AND RANGE TO THE LOWER 40S IN THE SOUTH. /22/ .LONG TERM...WEDNESDAY THROUGH MONDAY...MADE A FEW CHANGES TO THE PREVIOUS LONG TERM THIS AFTERNOON. STRONG COLD FRONT WILL MOVE THROUGH THE AREA TUESDAY NIGHT AND HIGH PRESSURE WILL FIRMLY HAVE A GRIP ON THE ARKLAMISS BY WEDNESDAY AFTERNOON. A REINFORCING SHOT OF COLD AIR WILL PUSH ACROSS THE AREA WEDNESDAY NIGHT INTO THURSDAY. STUCK NEAR GUIDANCE FOR OVERNIGHT LOWS THURSDAY...BUT DID CUT WELL BELOW GUIDANCE FOR HIGHS ON THURSDAY. BOTH THE EURO AND THE GFS INDICATE COLD H925 WITH THE GFS BEING COLDER RANGING FROM -10 TO -3C ACROSS THE AREA. THE EURO IS A LITTLE WARMER...BUT THIS WILL STILL EQUATE TO A COLD DAY ON THURSDAY WITH HIGHS GENERALLY IN THE UPPER 30S TO NEAR 40. HIGH PRESSURE WILL PREVAIL OVER THE AREA INTO FRIDAY...BUT THE HIGH OVER THE EAST COAST WILL BEGIN TO SHIFT TO THE SOUTH AND A MOIST SOUTHEASTERLY FLOW WILL BEGIN FRIDAY AFTERNOON. BOTH THE GFS/EURO PUSH MID LEVEL SHORT WAVES ACROSS THE AREA SATURDAY AND SUNDAY AND THIS COMBINED WITH THE MOIST FLOW SHOULD KICK OF SOME SHOWER THROUGH THE WEEKEND. THE LATEST RUN OF THE GFS KEEP THE RIDGE TO THE SOUTHEAST AND KEEPS US IN SOUTHERLY FLOW INTO TUESDAY WITH A POTENT SYSTEM MOVING THROUGH THE AREA LATE TUESDAY. THE EURO MOVES DEEPER SHORT WAVES ACROSS THE AREA...ONE ON SATURDAY AND A MORE SIGNIFICANT ONE LATE ON TUESDAY. WITH ALL OF THIS SAID PRETTY MUCH JUST WENT WITH GUIDANCE FOR POPS...BUT DID RAISE AFTERNOON HIGHS ABOVE GUIDANCE SATURDAY THROUGH MONDAY AS THE GFS/EURO INDICATE VERY H850/H925 TEMPS. STUCK WITH THE PREVIOUS LONG TERM FORECAST UNLESS OTHERWISE MENTIONED ABOVE SO WILL ATTACH THE PREVIOUS LONG TERM DISCUSSION./15/ PREVIOUS LONG TERM...WEDNESDAY THROUGH MONDAY. DID NOT MAKE ANY REAL CHANGES TO THE FORECAST AT THIS TIME. LOOKS LIKE THE WEATHER WILL BE QUIET FOR THE MOST PART...BUT THERE MAY BE A FEW COLD DAYS BEFORE THE NEXT CHANCE OF RAIN BY THE END OF THE WEEK. TWEAKED TEMPERATURES IN A FEW SPOTS...OVERALL GUIDANCE WAS GOOD. A COLD AIRMASS SETTLES OVER THE AREA BY THURSDAY...BRINGING ANOTHER SHOT OF ARCTIC AIR. LOW TEMPERATURES WILL BE BACK IN THE LOWER AND MID 20S FOR MUCH OF THE AREA BY WEDNESDAY NIGHT...WITH VALUES A FEW DEGREES COOLER BY THURSDAY NIGHT. HIGHS MAY NOT GET OUT OF THE 40S...BOTH WEDNESDAY AND THURSDAY. THE HIGH SHIFTS EAST BY FRIDAY AFTERNOON. CIRCULATION AROUND THE HIGH BRINGS IN SOME MOIST AND WARM AIR FROM THE GULF. FLOW ALOFT WAS ZONAL FOR MOST OF THE WEEK...HOWEVER A SHORT WAVE SWINGS THROUGH AROUND THURSDAY AND THE RIDGE BUILDS INTO THE PLAINS BY FRIDAY. THE UPPER RIDGE SHIFTS EAST AND FLATTENS BY FRIDAY. THE UPPER JET WAS BRINGING PLENTY OF PACIFIC MOISTURE INTO THE SOUTHWEST US. THE MODEL SHOWS A POTENT UPPER LOW SCALING THE WEST COAST BEFORE MOVING INLAND AROUND SATURDAY. A WARM FRONT SEEMS TO DEVELOP ACROSS THE SOUTHERN STATES AROUND SATURDAY. ALTHOUGH...MODELS DO NOT SHOW MUCH INSTABILITY...BUT SUSPECT IT WILL INCREASE THROUGH THE PERIOD. ANYWAY...MAINTAINED THUNDER FOR SATURDAY...MAY HAVE TO ADD THUNDER FOR THE FRIDAY NIGHT PERIOD. OVERALL THE EXTENDED FORECAST WAS GOOD. /07/ && .AVIATION...CLOUDS AND RAIN WILL INCREASE FROM THE WEST TONIGHT ALTHOUGH...VFR CONDITIONS CAN BE EXPECTED THROUGH 06Z TUESDAY. CEILINGS WILL GRADUALLY LOWER FROM THE WEST AFTER MIDNIGHT. MVFR CEILINGS CAN BE EXPECTED IN THE WEST BY 08Z GRADUALLY DECREASING TO IFR BY 12Z TUESDAY. SOME LIFR CEILINGS CAN ALSO BE EXPECTED. THUNDERSTORMS WILL BE POSSIBLE OVER THE CENTRAL AND SOUTHERN PORTIONS OF THE AREA BY 18Z AND CONTINUE THROUGH 23Z. /22/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 39 53 36 50 / 41 60 13 6 MERIDIAN 34 53 36 51 / 28 59 14 6 VICKSBURG 42 53 37 47 / 51 61 13 6 HATTIESBURG 38 60 41 52 / 16 54 17 9 NATCHEZ 44 59 39 51 / 36 51 35 8 GREENVILLE 38 45 32 47 / 78 76 7 6 GREENWOOD 38 46 32 48 / 69 77 7 6 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ SHORT TERM/AVIATION: 22 LONG TERM:15/07 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1212 PM CST MON JAN 21 2008 ...UPDATE TO PUBLIC AND AVIATION DISCUSSIONS... .UPDATE... HAVE STARTED RECEIVING GROUND TRUTH TO RADAR RETURNS OVER THE PAST COUPLE OF HOURS ROUGHLY SOUTH OF HIGHWAY 60 AND WEST OF HIGHWAY 65. MOST OF THE REPORTS CONSISTED OF VERY LIGHT SNOW OR SLEET...OR A COMBINATION OF THE TWO. THE RADAR ECHOES AND REPORTS HAVE COINCIDED FAIRLY WELL WITH SOME COOLER CLOUD TOPS...COLDER THAN -15C...AS DEPICTED ON IR IMAGERY. LIKELY GETTING AT LEAST SOME ICE CRYSTALS IN THE CLOUDS IN THESE AREAS...THUS AIDING THE PRECIPITATION PROCESS. MODELS ARE HANDLING THIS MID LEVEL MOISTURE RATHER POORLY...WITH THE EXCEPTION OF THE RUC13. HAVE FOLLOWED THIS MODEL CLOSELY FOR THE REMAINDER OF TODAY. EXPECT THE LIGHT SHOWERY TYPE FROZEN PRECIPITATION TO CONTINUE AS WEAK SLUGS OF ISENTROPIC UPGLIDE SHIFT THROUGH THE AREA. ACCUMULATIONS WILL BE VERY MINOR. MADE UPDATES TO POP AND WEATHER GRIDS TO ACCOUNT FOR ABOVE THINKING. HAVE ALSO LOWERED TEMPERATURES OVER MANY AREAS...ESPECIALLY THOSE THAT SAW A QUICK INCREASE IN CLOUDS JUST AFTER SUNRISE. HOURLY AND FIRE WEATHER GRIDS HAVE ALSO BEEN TWEAKED. UPDATED PUBLIC AND FIRE WEATHER FORECASTS ALREADY SENT. SCHAUMANN && .DISCUSSION... MODELS REMAIN IN GOOD AGREEMENT SO THE IMPACT OF FREEZING RAIN / DRIZZLE ON ROADWAYS TONIGHT REMAINS MAIN FORECAST CONCERN. SHORT TERM...TODAY THROUGH TUESDAY GULF STRATUS NEARING THE RED RIVER WILL CONTINUE TO MAKE GOOD NORTHWARD PROGRESS ON 50+ KNOT LLVL JET. BASED UPON GFS SOUNDINGS...HAVE MAINTAINED LOW POPS FOR LIGHT RAIN OVER SE KS AND WRN MO THIS AFTERNOON BUT DELAYED POPS UNTIL TONIGHT OVER THE REST OF THE REGION. SOUNDINGS CONTINUE TO SHOW LIMITED DEPTH OF SATURATED COLUMN TO GENERALLY BETWEEN H9-H75 OVER THE WESTERN HALF OF THE CWA...WITH THE DRYING BELOW H9 EXPECTED TO LIMIT THE AMOUNT OF LIGHT FREEZING PCPN FROM HIGHWAY 65 WESTWARD INTO SE KS. AS FRONT NEARS THIS EVENING...VEERING WINDS TO ENHANCE CONVERGENCE SATURATING COLUMN TO GREATER DEPTH INCLUDING THE BOUNDARY LAYER PRIMARILY EAST OF HIGHWAY 65. TIMING / LENGTH OF PCPN AGAINST THE ARRIVAL OF SUB FREEZING TEMPERATURES EXPECTED TO RESULT IN ONLY A GLAZE OF ICING OVER MOST AREAS...THOUGH AREAS SOUTH OF I-44 WILL NEED TO BE MONITORED CLOSELY. SUBSIDENCE / DRYING ON TUESDAY TO END ANY REMAINING FREEZING DRIZZLE OR LIGHT SNOW FROM WEST TO EAST DURING THE MORNING. LONG TERM...WEDNESDAY INTO THE WEEKEND SECOND NORTHERN STREAM CLIPPER TO BRING A REINFORCING SHOT OF COLD AIR AND POSSIBLY A FEW FLURRIES TO CENTRAL MO WEDNESDAY. 00Z ECMWF TRENDING QUICKER IN KICKING ENERGY OUT OF WRN TROF...POSSIBLY LEADING TO ANOTHER LIGHT PRECIPITATION EVENT ON FRIDAY INTO THE WEEKEND. && .AVIATION... FOR THE 18Z TAF CYCLE...CEILINGS ACROSS SOUTHEAST KANSAS AND NORTHEAST OKLAHOMA ARE BEGINNING TO SLIP INTO THE MVFR CATEGORY. EXPECT THESE MVFR CEILINGS TO SPREAD INTO SOUTHWEST MISSOURI AROUND MID AFTERNOON. WILL ALSO SEE SHOWERS OF LIGHT SLEET CONTINUE ACROSS THE AREA THROUGH ABOUT ABOUT 22Z. CEILINGS WILL CONTINUE TO LOWER TONIGHT...LIKELY REACHING THE IFR CATEGORY BETWEEN 06Z AND 08Z. MAY EVEN SEE CEILINGS APPROACH THE LIFR CATEGORY LATE TONIGHT...ALONG WITH MVFR VISIBILITIES. LIGHT FROZEN PRECIPITATION IS ALSO EXPECTED UNTIL THE LATE OVERNIGHT HOURS. LIGHT FREEZING RAIN...LIGHT SNOW...LIGHT SLEET AND FREEZING DRIZZLE WILL ALL BE POSSIBLE. CEILINGS AND VISIBILITIES WILL SLOWLY IMPROVE FROM MID TO LATE MORNING ON TUESDAY. WINDS WILL REMAIN BRISK OUT OF THE SOUTH INTO EARLY THIS EVENING BEFORE SHIFTING TO THE NORTHWEST BEHIND A COLD FRONT. CONSIDERED WIND SHEAR GROUP WITH VEERING WINDS THIS EVENING AND WITH COLD FRONTAL PASSAGE LATER THIS EVENING. KEPT IT OUT FOR NOW BUT WILL CONTINUE TO MONITOR. SCHAUMANN && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo