AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 900 PM PST WED JAN 24 2007 .UPDATE...FOR THE CENTRAL CALIFORNIA INTERIOR...SATELLITE LOOPS SHOW CLEAR SKIES ACROSS THE CENTRAL CALIFORNIA INTERIOR THIS EVENING...AS HIGH PRESSURE ALOFT CONTINUES TO DOMINATE THE WEATHER FOR THE REGION. WITH CLEAR SKIES AND LIGHT WINDS...LOW TEMPERATURES THIS MORNING AGAIN DROPPED TO FREEZING OR LOWER. THE LOW AT FRESNO YOSEMITE AIRPORT THIS MORNING WAS 31 DEGREES...THE 19TH CONSECUTIVE MORNING WITH FREEZING TEMPERATURES. IF FRESNO DROPS TO 32 OR LOWER THURSDAY MORNING...IT WILL TIE THE RECORD FOR CONSECUTIVE DAYS WITH LOWS OF 32 OR BELOW OF 20 DAYS...SET FOR THE PERIOD JANUARY 3-22 1947. THERE ARE SIGNS THE AIRMASS OVER THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY MAY FINALLY BE BEGINNING TO MODERATE. THE GOES WATER-VAPOR LOOP SHOWS AN UPPER-LEVEL LOW NEAR 39N/131W. THIS LOW IS FORECAST TO APPROACH CAPE MENDOCINO OVER THE NEXT 24 HOURS...PUSHING THE UPPER-LEVEL RIDGE INLAND AND WEAKENING IT. A SHALLOW...PATCHY MARINE LAYER HAS DEVELOPED ALONG THE CENTRAL CALIFORNIA COAST... EVIDENCED ON BOTH THE GOES FOG LOOP AND THE FORT ORD WIND PROFILER. IN THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY...WARM AIR ABOVE THE INVERSION IS FINALLY MIXING DOWN...AND HIGH TEMPERATURES THIS AFTERNOON WERE IN THE MID 60S. FRESNO HAD A HIGH OF 65 DEGREES...THE WARMEST TEMPERATURE SINCE DECEMBER 9TH...WHEN THE HIGH WAS 67 DEGREES. BAKERSFIELD WAS A DEGREE WARMER AT 66...THE WARMEST MEADOWS FIELD HAS BEEN SINCE LAST CHRISTMAS DAY...WHEN THE HIGH ALSO WAS 66. AT 04Z...TEMPERATURES IN THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY WERE IN THE MID TO UPPER 40S /UP 0-2 DEGREES OVER 04Z WEDNESDAY... EXCEPT AT PORTERVILLE WHERE IT WAS 7 DEGREES WARMER/...AND DEWPOINTS RANGED FROM 24-31 /UP 1-6 DEGREES OVER 04Z WEDNESDAY...EXCEPT AT NAS LEMOORE WHERE THE DEWPOINT WAS DOWN 2 DEGREES/. LOW TEMPERATURES ACROSS THE CENTRAL AND SOUTH VALLEY THIS MORNING RANGED FROM 24 TO 32 DEGREES. EXPECT LOWS THURSDAY MORNING TO BE A DEGREE OR 2 WARMER...BUT STILL MOST LOWS WILL BE AT OR BELOW 32 DEGREES SO THE FROST ADVISORY LOOKS ON TRACK. MODEL GUIDANCE FORECASTS LOWS TO SLOWLY INCREASE OVER THE SHORT- TERM PERIOD. HOWEVER...ALL THREE MODEL MOS/S HAVE BEEN TOO WARM AT NIGHT...WITH THE NAM AND NGM GUIDANCE FOR FRESNO 2 DEGREES OFF THIS MORNING...WHILE THE GFS ENSEMBLE GUIDANCE WAS 4-6 DEGREES TOO WARM. ADJUSTING THE MODELS FOR THIS BIAS FOR TONIGHT YIELDS LOWS 32-33 DEGREES AT FRESNO...SO THE CURRENT FORECAST LOOKS ON TRACK. && && .AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR THURSDAY, JANUARY 25, 2007. WOOD BURNING IS DISCOURAGED IN FRESNO, KERN, KINGS, MADERA, MERCED AND TULARE COUNTIES. && .PREV DISCUSSION... /ISSUED 330 PM PST WED JAN 24 2007/ SHORT TERM...TONIGHT THROUGH SATURDAY...VERY LITTLE CHANGE IN THE CURRENT WEATHER PATTERN AS A RIDGE OF HIGH CONTINUES TO DOMINATE THE REGION. RUC80 UPPER AIR ANALYSIS NOW HAS THE RIDGE AXIS OVER THE WEST WITH TEMPERATURES INDICATING SOME WARMING THIS AFTERNOON. IN ADDITION...DEW POINTS ARE ALSO SHOWING A POSITIVE GAIN AS MOST VALLEY LOCATIONS HAD READING IN THE LOWER 30S. YET...AS DEW POINT VALUES TREND DOWN THIS EVENING...MOST LOCATIONS WILL DROP BACK INTO THE 20S WHICH SHOULD ALLOW TEMPERATURES TO FALL BACK TO THE LOWER 30S. AS THE LOWER ATMOSPHERE REMAINS RELATIVELY UNCHANGED...WILL SEE FROST ONCE MORE OVER THE SAN JOAQUIN VALLEY OVERNIGHT. BY THURSDAY ..MODELS PROG A TROF TO MOVE OVER THE BLOCKING HIGH PATTERN AND WEAKEN THE RIDGE. THIS WILL THAN ALLOW THE CLOSED CUTOFF LOW OVER NORTHWESTERN MEXICO TO BEGIN SHIFTING EAST. AS THE RIDGE PATTERN IS WEAKEN...MODELS SHOW PIECES OF VORT MAX ENERGY SWINGING AROUND THE LOW AND HELPING TO INCREASING THE CLOUD COVER OVER THE REGION. WITH SOME CLOUDS OVER THE REGION...MAY SEE OVERNIGHT TEMPERATURES BECOMING MORE MODERATED AND NOT REACHING THE FREEZING MARK. THEREFORE...WILL NOT MENTION FROST FOR THURSDAY NIGHT/FRIDAY MORNING AS ONLY THE COLDEST RURAL LOCATIONS WILL REACH 32 DEG-F. SO...WHILE MAX TEMPERATURES WILL SEE A COOLING TREND DURING THE SHORT TERM... OVERNIGHT LOW WILL BE SLIGHTLY WARMER. THIS WILL HOLD TRUE FOR FRIDAY NIGHT INTO SATURDAY AS CLOUD COVER CONTINUES AND WEAK SHORT WAVE RIDGING AHEAD OF ANOTHER TROF WILL NOT INFLUENCE THE AMOUNT OF AFTERNOON WARMING DURING THE DAY ON SATURDAY. MODEL UNCERTAINTY REMAINS HIGH ON HOW THE ATMOSPHERE WILL EVOLVE INTO THE WEEKEND WHICH PREVENTS THE PLACEMENT OF PRECIP POTENTIALS FOR SATURDAY. THEREFORE...WILL MAINTAIN A DRY FORECAST THROUGH THE SHORT TERM AND WAIT FOR BETTER MODEL CONSENSUS ON SATURDAY ON EXACTLY WHERE THE UPPER LOW WILL RESIDE DURING THAT TIME FRAME. LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MEDIUM RANGE MODELS CONTINUE TO HAVE A DIFFICULT TIME WITH THE EVENTUAL LOCATION OF AN OFFSHORE CUTOFF LOW UNDERNEATH A MEAN WEST COAST RIDGE DURING THIS PERIOD. EACH MODEL HAS A DIFFERENT SOLUTION AND THERE IS NO RUN TO RUN CONSISTENCY WITH ANY OF THE MODELS. MODELS ARE IN FAIRLY GOOD AGREEMENT WITH A PERSISTENT UPPER TROUGH OVER THE MIDWEST AND EASTERN PORTION OF THE COUNTRY WHICH WILL SUGGESTS THE CONTINUATION OF A BLOCKY PATTERN OVER NOAM. WITH SO MUCH UNCERTAINTY...WILL KEEP A PARTLY CLOUDY AND DRY FORECAST GOING ACROSS THE CWFA WITH TEMPS RUNNING FAIRLY CLOSE TO CLIMO. AVIATION...AREAS OF MVFR WILL CONTINUE ACROSS THE CENTRAL AND SOUTH SAN JOAQUIN VALLEY DUE TO HAZE. OTHERWISE...VFR CONDITIONS WILL PREVAIL ACROSS THE CENTRAL CA INTERIOR THROUGH 00Z FRIDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL...AND TWEB ROUTES 421 AND 423. AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR THURSDAY...JANUARY 25, 2007. WOOD BURNING IS DISCOURAGED IN FRESNO...KERN...KINGS...MADERA...MERCED AND TULARE COUNTIES. && .HNX WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PST THURSDAY FOR THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY /CAZ089>092/. && $$ SANGER/MOLINA/BEAN WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 930 PM EST THU JAN 25 2007 .UPDATE /TONIGHT/... HAVE UPDATED THE ZONE PACKAGE AND SEVERAL STATEMENTS FOR A NUMBER OF REASONS.... BASED ON CURRENT AND EXPECTED RADAR TRENDS, HAVE OPTED TO DROP THE SNOW ADVISORY FOR THE DELMARVA. WHILE THERE COULD BE SOME SCATTERED SNOW SHOWERS AROUND, THE CHANCE OF HEAVIER SQUALLS HAS DIMINISHED. STILL, BE CAUTIOUS WHILE DRIVING IN ANY SNOW SHOWERS. AS A RESULT OF THE CANCELED SNOW ADVISORY, HAVE ALSO MADE SOME ADJUSTMENTS TO POPS. STILL HAVE KEPT LOW CHANCE VALUES, BUT LOWERED SOME OF THE HIGHER CHANCES TO 30 TO 40 PERCENT. MADE SOME TWEAKS TO WORDING TO REMOVE EVENING REFERENCES. WSW UPDATE IS ALREADY OUT AND AN UPDATED SPS HAS ALREADY BEEN ISSUED. && .PREV DISCUSSION... /ISSUED 435 PM EST THU JAN 25 2007/ .SHORT TERM /TODAY THROUGH SUNDAY NIGHT/... THE ARCTIC AIR IS CURRENTLY FILTERING INTO THE CWA. DEWPOINTS ACROSS THE SOUTHERN POCONOS HAVE DROPPED TO AROUND ZERO. ACROSS THE DELMARVA, THEY RANGE FROM THE TEENS INTO THE LOWER 20S. THE FOCUS OF THIS SHORT TERM PERIOD WILL BE TONIGHT AS THE SECOND SHORT WAVE OF THE CALENDER DAY MAKES IT`S WAY ACROSS THE SOUTHERN PORTION OF THE REGION. THE FIRST WAS RESPONSIBLE FOR THE MIDDAY SNOW SQUALLS ACROSS THE NORTHERN HALF OF THE CWA. 12Z SOLUTIONS CONTINUE TO INDICATE THAT OUR WINDEX EVENT WILL CONTINUE INTO THE EVENING HOURS. THE INSTABILITY IS IN PLACE. WE EVEN FOUND CAPE FORECAST INTO THE 40 J/KG RANGE ACROSS THE DELMARVA PER THE ETA SOUNDINGS OFF BUFKIT. THE MOISTURE IS THERE AS IS THE LIFTING MECHANISM. INCORPORATING SOME NEWER TECHNIQUES, WE ALSO FOUND SOME NICE OMEGA/DENDRITE CROSSHAIRS. WHILE BOTH THE GFS AND THE WRF FOCUS ON THE DELMARVA REGION THIS EVENING, THEY CONCENTRATE THEIR QPF IN SLIGHTLY DIFFERENT AREA. THE GFS IS MORE TO THE NORTH. THE LATEST RUC40 AND STONEYBROOK MM5 GIVES MORE CREDENCE TO THE WRF. EARLIER THIS AFTERNOON, THE APPROACHING SHORT WAVE COULD BE SEEN ON THE VISIBLE SAT PIX AND LOOKED PRETTY HEALTHY. WHILE THERE MAY BE A DECREASE IN SNOW SHOWERS THE NEXT SEVERAL HOURS, WE ARE ANTICIPATING AN INCREASE IN COVERAGE ONCE AGAIN THIS EVENING. FOR THE ABOVE REASONS, WE WENT OUT WITH A SNOW ADVISORY FOR THE DELMARVA. WE CONTINUE TO THINK THAT DECENT BURSTS OF SNOW REMAIN LIKELY. NOT EVERYONE WILL SEE 1 OR 2 INCHES OF SNOW ACROSS THE DELMARVA, BUT WE FELT THAT THESE TYPE OF ACCUMULATIONS WOULD BE NUMEROUS ENOUGH TO NECESSITATE THE ADVISORY. WITH INCREASING WINDS OVERNIGHT, WINDCHILLS WILL BE QUITE NASTY TOMORROW MORNING. SINGLE DIGITS IN MANY SPOTS, WITH NEGATIVE VALUES ACROSS THE NORTHERN THIRD OF THE CWA. THE WINDCHILL ADVISORY REMAINS POSTED FOR THE SOUTHERN POCONOS AND EXTREME NORTHWEST NEW JERSEY. WINDS WILL CONTINUE TO INTENSIFY TOMORROW. GUSTS UP TO 40 MPH ARE NOT OUT OF THE QUESTION. WHILE WIDESPREAD WIND DAMAGE IS NOT EXPECTED, SOME TREES OR WIRES COULD COME DOWN. IT WON`T BE A FUN DAY WITHOUT HEAT TOMORROW WITH HIGHS ONLY GETTING INTO THE TEENS AND TWENTIES. THE STIFF OFFSHORE FLOW WILL BEGIN TO DECEASE TOMORROW NIGHT AS HIGH PRESSURE BUILD IN. THE NEXT THREAT OF PRECIPITATION APPEARS TO BE LATE IN THE WEEKEND FOR MOST OF US, BUT THE NORTHERN HALF OF THE CWA COULD HAVE FLURRIES/SNOW SHOWERS JUST ABOUT ANY TIME THOUGH PERIOD. TEMPERATURES ARE EXPECTED TO BE MORE SEASONAL COME SATURDAY. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... A COOLING TREND IS ONCE AGAIN EXPECTED AT THE BEGINNING OF THE NEXT WEEK. THE BEST CHANCE OF ANY PRECIP WILL RESIDE ACROSS THE NORTHERN ZONES WITH JUST SOME FLURRIES OR SNOW SHOWERS EXPECTED. IT APPEARS MOST OF THE ACTIVITY (PRECIPITATION) ALONG THE EAST COAST WILL REMAIN TO OUR SOUTH. && .AVIATION... SNOW SHOWERS MOVING THROUGH THE MID ATLANTIC WITH VERY BRIEF(LITERALLY MINUTES)LIFR CONDITIONS DUE TO VSBY. WINDS FROM THE WEST TO THE NORTHWEST WILL BE THE CASE RIGHT THROUGH TONIGHT INTO THE MID DAY HOURS ON FRIDAY. SKY-WISE, AFTER THE SHOWERS MOVE THROUGH SHOULD BE CRYSTAL CLEAR ESPECIALLY NORTHERN AREAS. DOWN SOUTH, SOME CONCERN WITH A BAND OF SNOW SETTING UP FROM SOUTHCENTRAL PA SOUTHEAST TO SOUTHERN DEL BAY. STILL WORKING ON THAT POTENTIAL. MEANWHILE, THE COLDEST AIR OF THE SEASON ARRIVES WITH A STINGING WIND AFTER SUNSET. THERE IS A NOTAM FOR MIV FOR EQUIP PROBLEMS, BUT ACY TAF SHOULD SUFFICE FOR MIV TOO GIVEN THE SYNOPTIC PATTERN. && .MARINE... VERY STRONG WIND GRADIENT WILL BE SETTING UP THIS EVENING AND LAST THROUGH FRIDAY. GALES GOING UP IN THE NEARSHORE WATERS AND STORM WARNINGS BEYOND THAT FOR THE MID ATLC WATERS. VERY COLD AIRMASS WILL SWEEP ACROSS THE REGION WITH WIND CHILLS UNDER 10 DEGREES. THERE WILL BE SOME SNOW SHOWERS ACCOMPANYING THE COLD AND ANYONE HEADING DOWN THE DELAWARE COAST MAY ENCOUNTER SOME WHITEOUT CONDITIONS AS COLD AIR BLOWS OVER VERY WARM SEA SURFACE TEMPERATURES IN THE UPPER 40S. HIGHEST WAVES IN THE NEARSHORE WATERS LIKELY TO BE AROUND 7 FT WITH 5 FT IN THE LOWER BAY. HAVE CALCULATED THE ICING POTENTIAL GIVEN AIR/SEA/WIND COMPONENTS AND IT TRANSLATES TO A LIGHT FREEZING SPRAY. DEL BAY LIKELY TO HAVE THE THREAT ACROSS THE LOWER END WHERE SEAS WILL BE OVER 5 FT AND THE WIND SHEARING OFF THE WHITE CAPS. AFTER A MINOR TEMPERATURE RECOVERY, ANOTHER FRONT WILL MOVE OFFSHORE SOMETIME LATE SUNDAY AND REINFORCE THE COLD AIR. LOW PRESSURE WILL FORM ON THE FRONT OFF THE SOUTHEAST COAST AND MOVE NORTHEAST WHILE HIGH PRESSURE BUILDS OVER THE MID SECTION. ONCE AGAIN THE GRADIENT TIGHTENS WITH MORE COLD AIR COMING IN FROM THE NORTH. FORESEEABLE FUTURE THEN IS CONTINUED COLD, SOME SNOW SHOWERS AT TIMES WITH GUSTY OFFSHORE WINDS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WIND CHILL ADVISORY FROM 3 AM TO 10 AM EST FRIDAY FOR PAZ054- 055. NJ...WIND CHILL ADVISORY FROM 3 AM TO 10 AM EST FRIDAY FOR NJZ001. DE...NONE. MD...NONE. MARINE...FREEZING SPRAY ADVISORY FROM 4 AM TO 7 PM EST FRIDAY FOR ANZ431-450>455. GALE WARNING UNTIL 8 PM EST FRIDAY FOR ANZ430-431-450>455. && $$ UPDATE...NIERENBERG SHORT TERM...KRUZDLO LONG TERM...KRUZDLO/HPC AVIATION/MARINE...EBERWINE de AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MOUNT HOLLY NJ 435 PM EST THU JAN 25 2007 .SHORT TERM /TODAY THROUGH SUNDAY NIGHT/... THE ARCTIC AIR IS CURRENTLY FILTERING INTO THE CWA. DEWPOINTS ACROSS THE SOUTHERN POCONOS HAVE DROPPED TO AROUND ZERO. ACROSS THE DELMARVA, THEY RANGE FROM THE TEENS INTO THE LOWER 20S. THE FOCUS OF THIS SHORT TERM PERIOD WILL BE TONIGHT AS THE SECOND SHORT WAVE OF THE CALENDER DAY MAKES IT`S WAY ACROSS THE SOUTHERN PORTION OF THE REGION. THE FIRST WAS RESPONSIBLE FOR THE MIDDAY SNOW SQUALLS ACROSS THE NORTHERN HALF OF THE CWA. 12Z SOLUTIONS CONTINUE TO INDICATE THAT OUR WINDEX EVENT WILL CONTINUE INTO THE EVENING HOURS. THE INSTABILITY IS IN PLACE. WE EVEN FOUND CAPE FORECAST INTO THE 40 J/KG RANGE ACROSS THE DELMARVA PER THE ETA SOUNDINGS OFF BUFKIT. THE MOISTURE IS THERE AS IS THE LIFTING MECHANISM. INCORPORATING SOME NEWER TECHNIQUES, WE ALSO FOUND SOME NICE OMEGA/DENDRITE CROSSHAIRS. WHILE BOTH THE GFS AND THE WRF FOCUS ON THE DELMARVA REGION THIS EVENING, THEY CONCENTRATE THEIR QPF IN SLIGHTLY DIFFERENT AREA. THE GFS IS MORE TO THE NORTH. THE LATEST RUC40 AND STONEYBROOK MM5 GIVES MORE CREDENCE TO THE WRF. EARLIER THIS AFTERNOON, THE APPROACHING SHORT WAVE COULD BE SEEN ON THE VISIBLE SAT PIX AND LOOKED PRETTY HEALTHY. WHILE THERE MAY BE A DECREASE IN SNOW SHOWERS THE NEXT SEVERAL HOURS, WE ARE ANTICIPATING AN INCREASE IN COVERAGE ONCE AGAIN THIS EVENING. FOR THE ABOVE REASONS, WE WENT OUT WITH A SNOW ADVISORY FOR THE DELMARVA. WE CONTINUE TO THINK THAT DECENT BURSTS OF SNOW REMAIN LIKELY. NOT EVERYONE WILL SEE 1 OR 2 INCHES OF SNOW ACROSS THE DELMARVA, BUT WE FELT THAT THESE TYPE OF ACCUMULATIONS WOULD BE NUMEROUS ENOUGH TO NECESSITATE THE ADVISORY. WITH INCREASING WINDS OVERNIGHT, WINDCHILLS WILL BE QUITE NASTY TOMORROW MORNING. SINGLE DIGITS IN MANY SPOTS, WITH NEGATIVE VALUES ACROSS THE NORTHERN THIRD OF THE CWA. THE WINDCHILL ADVISORY REMAINS POSTED FOR THE SOUTHERN POCONOS AND EXTREME NORTHWEST NEW JERSEY. WINDS WILL CONTINUE TO INTENSIFY TOMORROW. GUSTS UP TO 40 MPH ARE NOT OUT OF THE QUESTION. WHILE WIDESPREAD WIND DAMAGE IS NOT EXPECTED, SOME TREES OR WIRES COULD COME DOWN. IT WON`T BE A FUN DAY WITHOUT HEAT TOMORROW WITH HIGHS ONLY GETTING INTO THE TEENS AND TWENTIES. THE STIFF OFFSHORE FLOW WILL BEGIN TO DECEASE TOMORROW NIGHT AS HIGH PRESSURE BUILD IN. THE NEXT THREAT OF PRECIPITATION APPEARS TO BE LATE IN THE WEEKEND FOR MOST OF US, BUT THE NORTHERN HALF OF THE CWA COULD HAVE FLURRIES/SNOW SHOWERS JUST ABOUT ANY TIME THOUGH PERIOD. TEMPERATURES ARE EXPECTED TO BE MORE SEASONAL COME SATURDAY. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... A COOLING TREND IS ONCE AGAIN EXPECTED AT THE BEGINNING OF THE NEXT WEEK. THE BEST CHANCE OF ANY PRECIP WILL RESIDE ACROSS THE NORTHERN ZONES WITH JUST SOME FLURRIES OR SNOW SHOWERS EXPECTED. IT APPEARS MOST OF THE ACTIVITY (PRECIPITATION) ALONG THE EAST COAST WILL REMAIN TO OUR SOUTH. && .AVIATION... SNOW SHOWERS MOVING THROUGH THE MID ATLANTIC WITH VERY BRIEF(LITERALLY MINUTES)LIFR CONDITIONS DUE TO VSBY. WINDS FROM THE WEST TO THE NORTHWEST WILL BE THE CASE RIGHT THROUGH TONIGHT INTO THE MID DAY HOURS ON FRIDAY. SKY-WISE, AFTER THE SHOWERS MOVE THROUGH SHOULD BE CRYSTAL CLEAR ESPECIALLY NORTHERN AREAS. DOWN SOUTH, SOME CONCERN WITH A BAND OF SNOW SETTING UP FROM SOUTHCENTRAL PA SOUTHEAST TO SOUTHERN DEL BAY. STILL WORKING ON THAT POTENTIAL. MEANWHILE, THE COLDEST AIR OF THE SEASON ARRIVES WITH A STINGING WIND AFTER SUNSET. THERE IS A NOTAM FOR MIV FOR EQUIP PROBLEMS, BUT ACY TAF SHOULD SUFFICE FOR MIV TOO GIVEN THE SYNOPTIC PATTERN. && .MARINE... VERY STRONG WIND GRADIENT WILL BE SETTING UP THIS EVENING AND LAST THROUGH FRIDAY. GALES GOING UP IN THE NEARSHORE WATERS AND STORM WARNINGS BEYOND THAT FOR THE MID ATLC WATERS. VERY COLD AIRMASS WILL SWEEP ACROSS THE REGION WITH WIND CHILLS UNDER 10 DEGREES. THERE WILL BE SOME SNOW SHOWERS ACCOMPANYING THE COLD AND ANYONE HEADING DOWN THE DELAWARE COAST MAY ENCOUNTER SOME WHITEOUT CONDITIONS AS COLD AIR BLOWS OVER VERY WARM SEA SURFACE TEMPERATURES IN THE UPPER 40S. HIGHEST WAVES IN THE NEARSHORE WATERS LIKELY TO BE AROUND 7 FT WITH 5 FT IN THE LOWER BAY. HAVE CALCULATED THE ICING POTENTIAL GIVEN AIR/SEA/WIND COMPONENTS AND IT TRANSLATES TO A LIGHT FREEZING SPRAY. DEL BAY LIKELY TO HAVE THE THREAT ACROSS THE LOWER END WHERE SEAS WILL BE OVER 5 FT AND THE WIND SHEARING OFF THE WHITE CAPS. AFTER A MINOR TEMPERATURE RECOVERY, ANOTHER FRONT WILL MOVE OFFSHORE SOMETIME LATE SUNDAY AND REINFORCE THE COLD AIR. LOW PRESSURE WILL FORM ON THE FRONT OFF THE SOUTHEAST COAST AND MOVE NORTHEAST WHILE HIGH PRESSURE BUILDS OVER THE MID SECTION. ONCE AGAIN THE GRADIENT TIGHTENS WITH MORE COLD AIR COMING IN FROM THE NORTH. FORESEEABLE FUTURE THEN IS CONTINUED COLD, SOME SNOW SHOWERS AT TIMES WITH GUSTY OFFSHORE WINDS. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WIND CHILL ADVISORY FROM 3 AM TO 10 AM EST FRIDAY FOR PAZ054- 055. NJ...WIND CHILL ADVISORY FROM 3 AM TO 10 AM EST FRIDAY FOR NJZ001. DE...SNOW ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST FRIDAY FOR DEZ001>004. MD...SNOW ADVISORY FROM 7 PM THIS EVENING TO 4 AM EST FRIDAY FOR MDZ008-012-015-019-020. MARINE...FREEZING SPRAY ADVISORY FROM 4 AM TO 7 PM EST FRIDAY FOR ANZ431-450>455. GALE WARNING UNTIL 8 PM EST FRIDAY FOR ANZ430-431-450>455. && $$ SHORT TERM...KRUZDLO LONG TERM...KRUZDLO/HPC AVIATION/MARINE...EBERWINE de AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 730 PM EST FRI JAN 26 2007 .SYNOPSIS... 00Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING MAIN POLAR VORTEX NOW PUSHING OFF THE NORTHEAST COAST TAKING MUCH OF THE EXTREME COLD EXPERIENCED ACROSS THE NORTHEAST THE PAST 48 HOURS WITH IT. FURTHER UPSTREAM WE SEE YET ANOTHER POTENT UPPER DISTURBANCE SINKING SOUTH THROUGH ONTARIO TOWARD THE NORTHERN GREAT LAKES AND UPPER MISSISSIPPI VALLEY. ASSOCIATED WITH TH SOUTHERN STREAM WE SEE SOME WEAK RIDGING BUILDING OVER OUR AREA AT THIS TIME...FOLLOWED CLOSELY BY AN UPPER DISTURBANCE MOVING EASTWARD ACROSS TEXAS. THIS SYSTEM WILL EVENTUALLY DEVELOP LOW PRESSURE ACROSS THE NORTHERN GULF DURING SATURDAY EFFECTING OUR REGION BY SATURDAY EVENING. AT THE SURFACE...HIGH PRESSURE IS NOW JUST ABOUT DIRECTLY OVERHEAD...AND WILL CONTINUE TO DOMINATE OUR WEATHER THROUGH THE FIRST HALF OF SATURDAY. .DISCUSSION... WITH THE SETTING OF THE SUN...HIGH PRESSURE OVERHEAD...CLEAR SKIES AND VERY DRY AIR WILL SET UP NEAR IDEAL RADIATIONAL COOLING CONDITIONS THIS EVENING INTO THE OVERNIGHT. TEMPERATURES ARE LIKELY TO PLUMMET BY LATE EVENING INTO THE 30 MOST LOCATIONS AND ARE EVEN NOW FALLING RAPIDLY THROUGH THE 40S. GUIDANCE STILL HAVE A HARD TIME LATCHING ON TO A CONSENSUS LOW TEMPERATURE FORECAST OVERNIGHT. ONCE AGAIN WENT ON THE WARMER SIDE OF THE GUIDANCE...AND STILL FEEL THIS WAS THE WAY TO GO. STILL EVEN ON THIS WARMER SIDE...TEMPS SHOULD FALL BELOW THE FREEZING MARK FOR MOST LOCATIONS AWAY FROM THE IMMEDIATE COAST AND EVEN INTO THE MIDDLE AND UPPER 20S FOR THE COLDER INLAND LOCATIONS. ONE THING THAT COULD ADD SOME UNCERTAINTY TO THE FORECAST IS THE BEGINNING OF A MID/UPPER LEVEL MOISTURE SURGE ACROSS THE WESTERN AND CENTRAL GULF OF MEXICO. IF SOME OF THIS HIGH CLOUDS IS ABLE TO REACH OUR AREA DURING THE LATE NIGHT HOURS IT WOULD LIKELY SLOW OR STOP THE COOLING PROCESS. BELIEVE THIS IS OF LOW PROBABILITY AT THIS TIME AND WILL WAIT A WHILE LONGER...IN ORDER TO BETTER ANALYZE SATELLITE TRENDS BEFORE MAKING ANY CHANGES. THIS HIGH LEVEL MOISTURE WILL ALMOST CERTAINLY OVERSPREAD OUR SKIES DURING THE DAY ON SATURDAY. AT THIS POINT...IT WOULD SEEM ANY SHOWERS/AREAS OF RAIN WOULD HOLD OFF UNTIL THE EARLY TO MID EVENING HOURS. && .AVIATION... UNRESTRICTED VISIBILITY...CLEAR SKIES...AND LIGHT WINDS WILL CONTINUE THROUGH TONIGHT AND SATURDAY MORNING. A BROKEN LAYER OF CS (AROUND 25K FT) WILL DEVELOP BY LATE SATURDAY MORNING AND AFTERNOON AS A LOW PRESSURE SYSTEM RAPIDLY DEVELOPS IN THE GULF. RAIN CHANCES WILL QUICKLY INCREASE AFTER THE END OF THIS TAF PERIOD (00 UTC SUNDAY). && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...NONE. GM...NONE. && $$ AVIATION...FOURNIER REST OF DISCUSSION...MROCZKA fl AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE TALLAHASSEE FL 312 PM EST FRI JAN 26 2007 ...FREEZING TEMPERATURES EXPECTED ACROSS THE REGION TONIGHT... .SYNOPSIS...CLEAR BUT COOL DAY ACROSS THE REGION WITH TEMPERATURES WARMING INTO THE MID TO UPPER 50S AT THIS HOUR. WE SHOULD TOP OUT NEAR 60 IN OUR FLORIDA COUNTIES. DEWPOINTS HAVE PLUMMETED AS EXPECTED AND HAVE DROPPED INTO THE LOWER TEENS IN SOME PLACES. THE 1027MB SURFACE HIGH IS NOW CENTERED BETWEEN BIRMINGHAM AND MONTGOMERY. UPPER AIR ANALYSIS FROM THE RUC80 AT 18UTC ALONG WITH SATELLITE DATA IS SHOWING THE UPPER LOW THAT HAD BEEN PARKED OVER THE DESERT SOUTHWEST NEAR THE MEXICAN BORDER IS FINALLY ON THE MOVE. SHORTWAVE RIDGING IS SPREADING EASTWARD AND WILL LIKELY SIT RIGHT OVER OUR CWA BY NIGHTFALL. && .SHORT TERM (TONIGHT THROUGH SUNDAY NIGHT)... IT`S GOING TO BE COLD. HAVE STRUGGLED THE LAST COUPLE OF DAYS WITH THIS PARTICULAR FORECAST WITH REGARDS TO MINIMUM TEMPERATURES DUE TO CONFLICTING SIGNALS BETWEEN GLOBAL MODELS AND VARIOUS ENSEMBLE PACKAGES. I THINK TODAY THERE HAS BEEN SOME CLUES PROVIDED BY THE NEW 12Z DATA. SO THERE IS A LITTLE MORE CONFIDENCE TODAY IN TONIGHT`S FORECAST THAN I HAD JUST 24 HOURS AGO. BEYOND THIS TIME FRAME...THE MODELS REMAIN IN GOOD TO EXCELLENT AGREEMENT WITH THE OVERALL PATTERN...ESPECIALLY IN REGARDS TO THE GULF LOW PROGGED TO DEVELOP ON SATURDAY. GLOBAL MODELS ALSO CONTINUE TO SHOW THAT WE WILL BE IN A COLD PATTERN FOR SOME TIME. TONIGHT...CLEAR AND COLD WITH HIGH PRESSURE IN CONTROL. NOW...JUST HOW COLD IS IT GOING TO GET AND WHERE? LATEST MAV GUIDANCE HAS CONTINUED TO SHOW COLD TEMPERATURES JUST LIKE ITS PREDECESSORS. THE MET HAS ACTUALLY DROPPED A FEW DEGREES ACROSS THE BOARD AND NOW IS INDICATING A FREEZE AT ALMOST ALL INLAND LOCATIONS. BIAS FIELDS ALSO SUPPORT FREEZING TEMPERATURES AS WELL AS THE 26/00Z ENSEMBLES. ONLY OUTLIER TO FREEZING TEMPERATURES IS THE 26/09Z SREF WHICH HAS VERY LOW PROBABILITIES FOR SUB FREEZING TEMPERATURES. GIVEN ALL THE DATA SUPPORTING FREEZING TEMPS...WILL CONTINUE THIS IN THE FORECAST. ADDITIONALLY...CURRENT OBSERVATIONS ARE NOT QUITE AS WARM AS WE WERE EXPECTING. THUS...TEMPERATURES TONIGHT MAY BE ABLE TO DROP A LITTLE LOWER. WILL THEREFORE LOWER MIN TEMPS ACROSS EASTERN AREAS FROM WHAT I INHERITED A COUPLE OF DEGREES. THIS PRODUCES A CORRIDOR OF TEMPERATURES FROM TLH TO VLD AND SOUTHWARD TO CTY DOWN IN THE 26 TO 28 DEGREE RANGE. AREAS WEST OF THE OCHLOCKNEE/CHATTAHOOCHEE RIVERS SHOULD BE A LITTLE WARMER AS I AM EXPECTING A LIGHT ONSHORE FLOW TO SET UP BEFORE DAYBREAK AS THE SURFACE HIGH SHIFTS EASTWARD. SINCE I`M NOT FORECASTING A WIDESPREAD AREA OF TEMPERATURES BELOW 25 DEGREES WILL NOT BE ISSUING A HARD FREEZE WARNING. SATURDAY...AFTER A VERY COLD START TO THE DAY...THINGS WILL BE CHANGING FAST BY AFTERNOON. PREVIOUSLY STALLED UPPER LOW WILL OPEN UP INTO A SHORTWAVE AND RACE EASTWARD TOWARD THE SOUTHEAST BY MID DAY. THIS SHORTWAVE WILL INITIATE DEVELOPMENT OF A SURFACE LOW IN THE GULF OF MEXICO THAT WILL SPREAD EASTWARD THROUGHOUT THE DAY. BY LATE AFTERNOON (21Z) RAIN CHANCES WILL BE INCREASING OVER THE WESTERN AREAS WITH SKIES BECOMING MOSTLY CLOUDY ALMOST ALL AREAS. TEMPERATURES WILL BE ABLE TO WARM INTO THE MIDDLE 60S OVER THE EASTERN AREAS AS WARM ONSHORE FLOW COMBINES WITH PARTIAL SUNSHINE. SATURDAY NIGHT...SURFACE LOW AND SHORTWAVE WILL BE PASSING JUST SOUTH OF THE FLORIDA PANHANDLE DURING THE EVENING AND OVERNIGHT HOURS. THIS IS SIGNIFICANT BECAUSE EARLIER RUNS OF THE NAM INDICATED THIS LOW MIGHT BE FURTHER NORTH. THIS WOULD PUT A PORTION OF THE REGION IN THE WARM SECTOR AND THEREFORE GIVE THE POSSIBILITY OF SOME THUNDERSTORMS. HOWEVER...NOW THAT BOTH THE NAM AND GFS AGREE WITHIN 50 MILES ON THE TRACK OF THE SURFACE LOW IT LOOKS LIKE ALMOST ALL OF THE REGION SHOULD REMAIN IN THE COOL SECTOR OF THIS LOW AND THEREFORE NOT HAVE THE POTENTIAL FOR ANY THUNDERSTORMS. THE NAM DOES HAVE A LITTLE BIT OF INSTABILITY RIGHT ALONG THE IMMEDIATE COAST IN FLORIDA...SO WILL MENTION ISOLATED TS IN THE COASTAL WATERS. WILL INCREASE POPS TO CATEGORICAL OVER THE SOUTHEAST FLA BIG BEND NEARER TO WHERE THE SURFACE LOW WILL BE TRACKING AND KEEP HIGH LIKELY POPS (70 PERCENT ELSEWHERE). SINCE THIS WILL BE A QUICK MOVING STORM...QPF AMOUNTS SHOULD BE LESS THAN AN INCH WITH THE HEAVIEST AMOUNTS DOWN TOWARD CTY. SHOULD SEE RAIN DECREASING AFTER 06Z NORTHWESTERN AREAS AND COMING TO AN END ACROSS THE ENTIRE CWA BY 12Z AS THE SURFACE LOW AND SHORTWAVE MOVE AWAY. SUNDAY...ONCE THE SURFACE LOW DEPARTS WILL HAVE SKIES CLEARING BY AFTERNOON WITH ANOTHER COLD CANADIAN HIGH PRESSURE AREA MOVING OVER THE SOUTHEAST. COULD BE QUITE BREEZY IN THE AFTERNOON AS THE PRESSURE GRADIENT WILL INITIALLY BE TIGHT. HIGH TEMPERATURES WILL STRUGGLE UNDER COLD ADVECTION TO RECOVER INTO THE MID TO UPPER 50S. SUNDAY NIGHT...ARCTIC HIGH PRESSURE WILL ONCE AGAIN SETTLE OVER THE CWA BRINGING ANOTHER COLD AIR OUTBREAK. WILL FOLLOW CLOSE TO THE MAV/MET GUIDANCE BLEND HERE WHICH GIVES A POTENTIAL HARD FREEZE FOR THE NORTHWESTERN THIRD OF THE CWA WITH A LIGHT FREEZE ELSEWHERE. .LONG TERM (MONDAY THROUGH FRIDAY)... A MEAN TROUGH WILL ENCOMPASS THE ERN 2/3 OF THE LOWER 48 DURING THE PERIOD. HIGH PRESSURE WILL MAINTAIN BELOW NORMAL TEMPS AND DRY CONDITIONS FOR MONDAY AND TUESDAY. LOOKS LIKE THE LATTER HALF OF THE WEEK HAS BECOME SOMEWHAT UNSETTLED AS THE GFSX REVERSED ITS DRY TREND. INITIALLY A LOW PRESSURE SYSTEM DEVELOPS OVER THE WRN GULF LATE TUESDAY AND MOVES ACROSS THE ERN GULF AND FL ON WEDNESDAY. IN ITS WAKE...A RATHER POTENT SHORT WAVE AND SURFACE COLD FRONT SWEEP ACROSS THE ERN CONUS THURSDAY NIGHT AND FRIDAY. HIGH TEMPS WEDNESDAY AND THURSDAY MODERATE CLOSE TO NORMAL LEVELS THEN FALL BELOW NORMAL ON FRIDAY. ---LONG TERM UPDATE--- LATEST 12Z MEX INDICATES A LOW TEMPERATURE AT TLH DOWN TO 18 DEGREES FOR TUESDAY MORNING. WHILE THIS WOULDN`T BE A RECORD...IT WOULD BE THE FIRST TIME IN A FEW YEARS WE`VE HAD MIN TEMPS DOWN IN THE TEENS. PREFER FOR NOW TO WAIT ANOTHER MODEL RUN BEFORE TAKING THE MIN DOWN ANY LOWER. I ALREADY HAVE MID 20S MOST SITES WHICH MATCH WELL WITH THE 26/12Z MEX GUIDANCE BIAS FIELDS. BUT WITH THIS COLD OF A PATTERN...IT WOULDN`T BE SURPRISING TO SEE FUTURE MODEL RUNS CONTINUE THIS TREND. && .AVIATION...VFR CONDITIONS WILL CONTINUE AT ALL TERMINAL AND ALONG BOTH TWEB ROUTES THROUGH TONIGHT. WINDS WILL BE SW REST OF THIS AFTERNOON OVER DHN, ABY AND PFN. CALM WINDS ARE EXPECTED AFTER SUNSET. HIGH CLOUDS DEVELOPING AFTER SUNRISE. && .MARINE...WINDS AND SEAS WILL CONTINUE TO DECREASE INTO THE EVENING HOURS AS HIGH PRESSURE BUILDS OVER THE REGION. WINDS AND SEAS WILL PICK UP AGAIN LATE TOMORROW AND POSSIBLY MEET SCA CRITERIA SATURDAY NIGHT THROUGH EARLY ON SUNDAY. AFTER THAT...WINDS AND SEAS SHOULD DECREASE AS HIGH PRESSURE ONCE AGAIN BUILDS OVER THE WATERS. && .FIRE WEATHER...RED FLAG WARNINGS FOR TODAY LOOK TO VERIFY WELL WITH RH VALUES DROPPING INTO THE LOW 20 PERCENT RANGE IN FLORIDA AND UPPER 10S TO LOW 20S IN GEORGIA. RED FLAG CONCERNS MAY RETURN FOR TOMORROW IN OUR FLORIDA COUNTIES WHERE LOW RELATIVE HUMIDITY VALUES COULD REACH CRITICAL LEVELS FOR AROUND FOUR HOURS IN OUR EASTERN COUNTIES...BUT AT THIS TIME THINK THAT DURATIONS SHOULD ONLY BE AROUND TWO TO THREE HOURS. && .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 26 65 45 59 27 / 00 10 70 10 05 PANAMA CITY 37 63 48 58 32 / 00 30 70 05 05 DOTHAN 32 61 41 54 25 / 00 30 70 05 05 ALBANY 28 61 42 55 25 / 00 10 70 05 05 VALDOSTA 27 65 45 59 28 / 00 10 70 10 05 CROSS CITY 28 67 48 63 29 / 00 10 80 10 05 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...RED FLAG WARNING UNTIL 6 PM EST FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN... CLAY...COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY... GRADY...IRWIN...LANIER...LEE...LOWNDES...MILLER... MITCHELL...QUITMAN...RANDOLPH...SEMINOLE...TERRELL... THOMAS...TIFT...TURNER...WORTH. FL...RED FLAG WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN... GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON... JEFFERSON...LAFAYETTE...LEON...LIBERTY...MADISON...TAYLOR... WAKULLA...WASHINGTON. GM...NONE. $$ AVIATION/FIRE WEATHER...BLOCK SHORT TERM/LONG TERM UPDATE/MARINE...GODSEY LONG TERM...JAMSKI fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 735 PM EST THU JAN 25 2007 .SYNOPSIS... 00Z WATER VAPOR AND H4 RUC ANALYSIS CONTINUES TO SHOW A STRONG LONGWAVE RIDGE COVERING THE WESTERN CONUS AND A DEEP TROUGH ACROSS THE EAST. THE AXIS OF THIS TROUGH IS NOW REACHING THE ATLANTIC SEABOARD AND IS ANCHORED BY A DISTINCT POLAR VORTEX DROPPING SOUTHEAST ACROSS SOUTHERN QUEBEC. THE ONLY OTHER FEATURE OF NOTE REMAINS THE CLOSED UPPER LOW ACROSS NORTHERN MEXICO. THIS FEATURE WILL BEGIN TO COME BACK EAST AGAIN IN THE NEXT 24 HOURS AND WILL BE EFFECTING OUR REGION BY THE END OF THE WEEKEND. AT THE SURFACE...SURFACE FRONT CONTINUES TO DROP RAPIDLY SOUTH INTO THE SOUTHERN GULF OF MEXICO WITH HIGH PRESSURE BUILDING SOUTHEAST INTO OUR AREA. SKIES HAVE CLEARED THIS PAST AFTERNOON AND A NICE STRETCH OF WEATHER...ALTHOUGH ON THE COOL SIDE...WILL BE WITH US INTO SATURDAY MORNING. .DISCUSSION... AS MENTIONED ABOVE...HIGH PRESSURE CURRENTLY CENTERED OVER THE MIDDLE MISSISSIPPI VALLEY WILL BUILD SOUTH AND EAST OVER THE NEXT 24 HOURS TO A POSITION DIRECTLY OVERHEAD BY FRIDAY EVENING. ALTHOUGH THE HIGH IS BUILDING IN TONIGHT...THE GRADIENT SHOULD REMAIN UP JUST ENOUGH TO NOT ALLOW COMPLETE DE-COUPLING OF THE BOUNDARY LAYER. THIS WILL KEEP TEMPS FROM REALLY BOTTOMING OUT. GUIDANCE IS IN VERY GOOD AGREEMENT WITH A CLUSTERING BETWEEN 29 AND 32 FOR MOST LOCATIONS AWAY FROM THE IMMEDIATE COAST. THIS MAY BE A COUPLE DEGREES TO COOL BUT FORECAST LOOKS IN LINE ENOUGH TO NOT WARRANT AN UPDATE AT THIS TIME. ALTHOUGH TEMPS WILL BE NEAR FREEZING...FROST SEEMS A BIT UNLIKELY AS ALL MOS GUIDANCE IS INDICATING DEWPOINT DEPRESSIONS OF AROUND 5-7 DEGREES AT THE TIME OF FREEZING TEMPS. NO LACK OF SUN FOR THE DAY ON FRIDAY...AND EVEN THOUGH TEMPS WILL STRUGGLE TO HIT THE 60 DEGREE MARK IN THE AFTERNOON...THE LIGHT WINDS ASSOCIATED WITH THE BUILDING HIGH WILL NOT MAKE THINGS FEEL MUCH COOLER. NO MAJOR CHANGES NEEDED TO THE MARINE FORECAST AT THIS TIME. OFFSHORE BUOYS SHOWING WINDS AROUND 15 KTS WITH GUSTS BETWEEN 20-23 KTS WHICH IS IN LINE WITH CURRENT FORECAST. && .AVIATION... VFR CONDITIONS...CLEAR SKIES...AND LIGHT WINDS WILL CONTINUE THROUGH FRIDAY EVENING. && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...RED FLAG WARNING FROM 2 PM TO 7 PM EST FRIDAY FOR THE FOLLOWING ZONES: BAKER...BEN HILL...BERRIEN...BROOKS...CALHOUN... CLAY...COLQUITT...COOK...DECATUR...DOUGHERTY...EARLY... GRADY...IRWIN...LANIER...LEE...LOWNDES...MILLER... MITCHELL...QUITMAN...RANDOLPH...SEMINOLE...TERRELL... THOMAS...TIFT...TURNER...WORTH. FL...RED FLAG WARNING UNTIL 7 PM EST /6 PM CST/ THIS EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...GADSDEN...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. RED FLAG WARNING FROM 11 AM EST /10 AM CST/ TO 7 PM EST /6 PM CST/ FRIDAY FOR THE FOLLOWING ZONES: BAY...CALHOUN... DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION...FOURNIER REST OF DISCUSSION...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1115 AM CST FRI JAN 26 2007 .DISCUSSION... UPDATED FORECAST TODAY FOR MORE SUNSHINE...A BIT STRONGER SW WINDS AND ELEVATED HIGHS UP A DEGREE OR TWO. THIS DUE TO MORE EXPECTED SUNSHINE AND STRONGER WARM AIR ADVECTION FROM STRONGER SW WINDS. HIGHS AROUND 40F FROM I-74 NE AND UPPER 40S SW OF A RUSHVILLE TO SPRINGFIELD TO TERRE HAUTE LINE. 16Z SURFACE MAP SHOWS 1028 MB HIGH PRESSURE OVER THE GULF COAST STATES CENTERED ON AL WHILE 1000 MB LOW PRESSURE EAST OF LAKE WINNIPEG WITH ITS COLD FRONT EXTENDING FROM CENTRAL MN TO THE SD/NE BORDER. VERY TIGHT PRESSURE GRADIENT ACROSS IL ALREADY WITH SW BREEZES 15 TO 25 MPH AND GUSTS APPROACHING 30 MPH. TEMPS WERE IN THE MID NE AND LOWER 40S SW AREAS. SUNNY SKIES ACROSS CENTRAL AND SE IL WHILE CLOUDS NE OF IL AND RACING SE. ALOFT A POTENT 515 DM 500 MB CUTOFF LOW WAS OVER LAKE WINNIPEG. RUC AND NAM/WRF BRING DEEP LOW PRESURE SE INTO LAKE SUPERIOR BY 00Z WHILE COLD FRONT SLIDES SE TOWARD IA/IL BORDER EARLY THIS EVENING. CENTRAL AND SE IL WILL STAY ON WARM SIDE OF SYSTEM TODAY WITH AMPLE SUNSHINE AND STRONG SW BREEZES AND GUSTS TO AROUND 30 MPH. STILL A 1 TO 3 INCH SNOW COVER TO MELT NORTH OF I-70 SO AN INVERSION REMAINS OVER THE SNOWFIELD AND TO KEEP TEMPS COOLER THAN WHAT COULD BE ACHIEVED IF BARE GROUND LIKE IN SE IL SINCE 850 MB TEMPS AROUND 6C. STILL AFTER LOOKING AT LAPS SOUNDINGS FELT IT WAS NECESSARY TO WARM HIGHS UP A DEGREE OR TWO WITH 50S JUST SW OF ILX CWFA FROM LITCHFIELD TO FLORA SW...ST LOUIS ALREADY UP TO 50F. && .PREV DISCUSSION... LATEST SURFACE ANALYSIS INDICATED HIGH PRESSURE RIDGE EXTENDING FROM SRN IL SOUTHWARD INTO EAST TX AND SINKING SE. DEVELOPING WARM FRONT ACROSS NEB AND CENT MO SEPARATED S/SW WINDS AND TEMPS IN 30S ACROSS THE PLAINS...FROM CALM WINDS AND TEMPS IN TEENS OVER IL. SOME FOG AND LOW STRATUS HAS DEVELOPED WHERE THIS LLVL WARM ADVECTION OVERRUNS SNOWPACK IN IA. SFC LOW PRESSURE SYSTEM NEAR LK WINNIPEG QUICKLY DROPPING SE IN CONTINUED FAST NW FLOW OVER CENTRAL CONUS. POTENT SHORTWAVE NOTED ON 00Z UPPER AIR ANALYSIS TOPPING UPPER RIDGE IN NW CANADA AND DIVING THROUGH NW TERRITORIES ATTM. FORECAST ISSUES ARE SEVERAL CHANCES OF TRACE TO LIGHT AMOUNTS OF PRECIP AS DISTURBANCES MOVE THROUGH IN DRY NW FLOW...AND TEMPS WITH BRIEF WARMUP TODAY FOLLOWED BY SHARP COOLOFF TO BELOW NORMAL BY SECOND HALF OF WEEKEND. SHORT TERM...TODAY THROUGH SUNDAY... STRONG WARM AIR ADVECTION WILL BE FOUND ACROSS THE REGION TODAY AIDED BY SW WINDS GUSTING TO 30MPH...ADVECTING IN PLAINS THERMAL RIDGE OF +5 TO +7C AT H850. FULL EXTENT OF THIS WARMING WILL NOT BE REALIZED AT THE SFC HOWEVER WHERE MELTING SNOWPACK IN PLACE LEADS TO AN INVERSION AND LIKELY A FAIR AMOUNT OF STRATUS. KEPT WITH TREND OF UNDERCUTTING GUIDANCE HIGHS AND WILL GENERALLY GO WITH UPPER 30S NE TO MID 40S SW...THOUGH BARE GROUND SE REGIONS COULD APPROACH UPPER 40S. SFC COLD FRONT WILL BE SLIDING SE DURING THE DAY...REACHING GBG BY EARLY EVENING...AND CLEARING LWV BY 12Z. CONVERGENCE ALONG THIS BOUNDARY AND SUFFICIENT LLVL MOISTURE COULD LEAD TO A FEW HOURS OF DZ/FZDZ ALONG AND IMMEDIATELY BEHIND THE FRONT MAINLY SE 1/2 WHERE SLIGHTLY BETTER MOISTURE FIELDS PRESENT. THIS WILL BE A BRIEF AND VERY LIGHT EVENT...IF IT OCCURS AT ALL OVERNIGHT. INITIAL SURGE OF MODERATE STRENGTH CAA FOR SATURDAY ON BRISK NW WINDS WILL PROBABLY LEAD TO STEADY OR SLOWLY FALLING TEMPERATURES DURING THE DAY. SHORTWAVE AHEAD OF MAIN SLUG OF COLD AIR SLATED TO ARRIVE SATURDAY AFTERNOON. SIGNIFICANT DISAGREEMENT AMONG SHORT AND MEDIUM RANGE MODELS ON PLACEMENT AND STRENGTH OF MAIN VORT MAX...WITH UKMET/GFS KEEPING A COMPACT VORT LOBE CAPABLE OF PRODUCING A SWATH OF LIGHTLY ACCUMULATING SNOWS ACROSS THE NE CWA. MEANWHILE NAM GENERATES MORE CHANNELED VORTICITY FAVORING FLURRIES. WILL LEAVE FLURRIES IN FCST AND ALLOW ANOTHER MODEL RUN TO REFINE VORT PATH AND STRENGTH. CHUNK OF -20C 850MB AIR MOVES IN SAT NIGHT AND SUNDAY YIELDING LOWS IN TEENS AND HIGHS IN TEENS/20S. SCATTERED FLURRIES ARE POSSIBLE ON SUNDAY WITH LINGERING HIGH LLVL RH AND DEEP CYCLONIC FLOW. SFC RIDGE TO SET UP ACROSS THE MS VALLEY SUNDAY NIGHT CLEARING SKIES ALLOWING FOR WIDESPREAD SINGLE DIGIT LOWS MON AM. LONG TERM...MONDAY THROUGH THURSDAY... NORTHWEST FLOW TO DOMINATE MONDAY AND TUESDAY LEADING TO CONTINUED NEAR/BELOW NORMAL TEMPS AND ANOTHER WEAK DISTURBANCES PASSING THROUGH...WITH LIGHT PRECIP CHANCE. WEAK CLIPPER SYSTEM SLATED TO MOVE THROUGH ON MONDAY NIGHT/TUES MORNING AND HAVE KEPT CHANCE OF FLURRIES MENTIONED. TIMING WILL BE DIFFICULT TO PIN DOWN AS WELL AS STRENGTH OF SYSTEM UNTIL NEAR EVENT GIVEN THE SCALE AND SPEED OF THESE DISTURBANCES. LATEST RUN OF MEDIUM RANGE MODELS SUGGEST A BRIEF PERIOD OF ZONAL FLOW FOR MID-WEEK AS HIGH PRESSURE PUSHES ACROSS THE MIDWEST. ALSO SOME SIGNALS OF AN ATTEMPT TO PHASE NRN/SRN STREAMS FOR A MORE SIGNIFICANT PRECIP THREAT NEAR OR EAST OF HERE MID TO LATE WEEK. HOWEVER...NO CHANGES MADE TO THE GRIDS BEYOND TUESDAY. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SCHAFFER il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1040 AM CST THU JAN 25 2007 .DISCUSSION... FORECAST WAS IN PRETTY GOOD SHAPE AND ONLY MADE MINOR TWEAKS WITH A BIT MORE CLOUD COVER ALONG AND NORTH OF I-74 AND SLIGHTLY COOLER COOLER. MOST AREAS SHOULD ENJOY A MOSTLY SUNNY DAY. BUT NW BREEZES OVER A 1 TO 3 INCH SNOW COVER (THOUGH LESS THAN 1 INCH IN SE IL) TO GIVE TEMPS ABOUT FIVE DEGREES COOLER THAN NORMAL. HIGHS RANGING FROM MID 20S NORTH ALONG I-74 TO AROUND 30F IN SE IL FROM I-70 SOUTH. 16Z/10 AM SURFACE ANALYSIS SHOWS 1031 MB POLAR HIGH PRESSURE RIDGING FROM WEST TEXAS ACROSS NW MO INTO CENTRAL IOWA AND UPPER MS VALLEY. NEARLY SUNNY SKIES ACROSS CENTRAL IL WITH PATCH OF LOW CLOUDS OF 3 TO 3.5 KFT OVER NORTHERN KNOX...STARK AND MARSHALL COUNTIES AND DRIFTING SLOWLY SE WHILE PATCHES OF LOW CLOUDS OF 2 TO 3 KFT IN SE IL NEAR FLORA. GALESBURG AND ALTONA HAD LIGHT SNOW CRYSTALS WITH CLEAR BLUE SKIES EARLIER THIS MORNING. NW WINDS 7 TO 15 MPH EXCEPT LIGHT WEST OF I-55 CLOSER TO HIGH PRESSURE IN MO/IA. TEMPS RANGE FROM 14F IN GALESBURG TO 29F IN LAWRENCEVILLE. ALOFT A 499 DM 500 MB CUTOFF POLAR VORTEX LOW WAS JUST EAST OF JAMES BAY CANADA WITH A DEEP UPPER LEVEL TROF OVER THE EASTERN U.S. WHILE UPPER LEVEL RIDGE OVER THE ROCKIES. RUC AND NAM/WRF BUILD HIGH PRESSURE INTO THE MID AND LOWER MS VALLEY THIS EVENING WITH LIGHT WINDS IN WESTERN IL MOVING INTO EASTERN IL AROUND SUNSET. CURULE SHOWS SCATTERED LOW CLOUDS OVER NE AREAS THIS AFTERNOON WHERE SKIES COULD BECOME PARTLY SUNNY FROM I-74 NORTH. SUNNY TO MOSTLY SUNNY SKIES ELSEWHERE. RUC AND NAM/WRF SIMILAR WITH HIGHS AROUND 21Z RANGING FROM NEAR 25F FROM I-74 NORTH TO AROUND 30F FAR SW CWFA WITH FLORA AND LAWRENCEVILLE AROUND FREEZING. && .PREV DISCUSSION... 00Z UPPER AIR ANALYSIS INDICATED DEEP NORTHWEST FLOW EXTENDING FROM CANADIAN PRAIRIES INTO MIDWEST. WEAK SHORTWAVES ROTATING AROUND POLAR VORTEX CENTERED OVER HUDSON BAY PRODUCING QUICK MOVING LIGHT BOUTS OF PRECIP. LITTLE IN THE WAY OF HEIGHT RISE/FALLS ON 500MB CHARTS INDICATIVE OF STABLE LONGWAVE PATTERN. AT THE SFC...HIGH PRESSURE EXTENDING FROM WESTERN ONTARIO DOWN THROUGH SRN ROCKIES LOOKS TO BUILD EASTWARD TODAY AS BROAD AREA OF PRESSURE RISES EXTENDS INTO THE MISSISSIPPI VALLEY. CLEARING SKIES OVER NW CWA HAVE ALLOWED TEMPS TO DIP INTO LOW TEENS THIS MORNING WITH AMPLE SNOWCOVER. MAIN FORECAST CONCERNS ARE LIGHT PRECIP CHANCES OVER NEXT FEW DAYS AS MINOR DISTURBANCES TRAVERSE AREA IN FAST/DRY NW FLOW...AND TEMPS THROUGH THE PERIOD WITH THE ARCTIC BEING TAPPED BY THIS WEEKEND. SHORT TERM...TODAY THROUGH FRIDAY... HIGH PRESSURE TO SLIDE DOWN MO VALLEY TODAY WITH EASTERN FLANK OF THIS FEATURE KEEPING LOCAL AREA IN ZONE OF NW BREEZES THROUGH THE DAY. WILL BANK ON SUBSIDENCE FROM 1030MB HIGH AND DRYING LOW LEVELS TO GIVE A MOSTLY SUNNY DAY...THOUGH WITH SNOWPACK EXPECT ANOTHER SEASONABLY COOL DAY WITH HIGHS A FEW DEGREES BELOW NORMAL. THIS HIGH IS PROGGED TO QUICKLY SETTLE INTO THE LOWER MS VALLEY BY FRIDAY MORNING AS NEXT LOW DIVES INTO NRN GREAT LAKES. THIS WILL LEAVE THE AREA IN A TIGHTENING PRESSURE GRADIENT AND ALSO DRAW PLAINS-STATES THERMAL RIDGE INTO THE REGION BY AFTERNOON ON STRONG SW WINDS. FACTORS HINDERING A GOOD WARMUP INCLUDE SNOW ON THE GROUND AND RESULTING LLVL INVERSION WHICH COULD TRAP MOISTURE INTO A SCT/BKN STRATUS TYPE CLOUD FIELD. HAVE UNDERCUT GUIDANCE...BUT HIGHS TO STILL REACH ABOVE NORMAL...MAINLY MID 30S NE TO AROUND 40 SW...AND SNOW-FREE GROUND SOUTH OF I-70 COULD PUSH L/M 40S. THE FIRST OF TWO COLD FRONTS SHOULD QUICKLY MOVE THROUGH THE REGION ON FRIDAY EVENING BACKING WINDS AROUND TO THE NW AND STARTING THE CAA PATTERN. MAIN DYNAMICS AND CONVERGENCE FOR PRECIP WILL REMAIN WELL TO OUR NORTHEAST OVER THE GREAT LAKES. HOWEVER...A BRIEF PERIOD OF WEAK FORCING SHOULD MOVE THROUGH OVERNIGHT POSSIBLY PRODUCING TRACE AMOUNTS...UP TO A COUPLE HUNDREDTHS OF LIQUID DZ/FZDZ. LONG TERM...SATURDAY THROUGH THURSDAY... IMPORTANT LONG WAVE PATTERN CHANGE WILL TAKE PLACE FRIDAY AND SATURDAY...AS AN UPPER LOW TOPS RIDGE IN NW CANADA AND PHASES WITH POLAR VORTEX OVER JAMES BAY. THIS WILL HELP TO DRIVE THE UPPER LEVEL FLOW OUT OF THE ARCTIC...SOUTHWARD INTO THE MIDWEST. MAIN COLD PUNCH TO ARRIVE SATURDAY EVENING BEHIND SECONDARY FRONT/TROUGH. AGAIN LITTLE MOISTURE TO WORK WITH BUT SOME FLURRIES COULD BE SQUEEZED OUT. 850MB TEMPS EXPECTED TO PLUMMET INTO A -15 TO -20C RANGE FOR SATURDAY NIGHT AND SUNDAY YIELDING LOWS IN THE SINGLE DIGITS TO TEENS DEPENDING ON CLOUD COVER...AND HIGHS IN UPPER TEENS/LOWER 20S. WITH CYCLONIC FLOW AND CAA CANNOT RULE OUT SOME FLURRIES ON SUNDAY AS RH REMAINS HIGH BELOW 800MB. CLIPPER TYPE SYSTEM COULD MOVE THROUGH THE MIDWEST MONDAY BRINGING NEXT CHANCE OF LIGHT/ACCUMULATING SNOWS BUT THESE DETAILS WILL BE HARD TO PIN DOWN UNTIL NEARER THE EVENT GIVEN FAST NW FLOW ALOFT. NO CHANGES MADE BEYOND MONDAY...BUT HIGHLY AMPLIFIED PATTERN TO CONTINUE WITH PRIMARILY NORTHWEST FLOW OVER THE AREA. && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HUETTL/SCHAFFER il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 1225 AM EST THU JAN 25 2007 .AVIATION DISCUSSION...FOR THE 06Z TAFS A FLOW OF UNSTABLE AIR FROM THE NORTHWEST WILL BE OVER INDIANA FOR MOST OF THE TAF PERIOD. AN UPPER LEVEL DISTURBANCE WILL MOVE THROUGH INDIANA FROM THE NORTHWEST OVERNIGHT. THIS WILL BRING AN AREA OF SNOW WITH IT. CONDITIONS WILL START OUT AS MVFR. AFTER 08Z CEILINGS WILL DECREASE TO IFR WITH VISIBILITIES REMAINING MVFR. THIS DISTURBANCE WILL MOVE SOUTH OF INDIANA BY 13Z ENDING THE SNOW. WITH LOW LEVEL MOISTURE REMAINING MVFR CEILING WITH VFR VISIBILITIES WILL OCCUR FOR MOST OF THE DAY. AFTER 22Z HIGH PRESSURE WILL BUILD INTO INDIANA. DRIER AND MOST STABLE AIR WILL MOVE IN AFTER 00Z GIVING CLEAR SKIES AND UNRESTRICTED VISIBILITIES. && .SHORT TERM /TONIGHT AND THURSDAY/... MAIN SHORT TERM FOCUS WILL BE ON SNOW CHANCES LATER TONIGHT INTO THURSDAY. SATELLITE SHOWS LOTS OF LOW CLOUDS ACROSS OUR REGION. ALTHOUGH SEVERAL HOLES WERE OCCURRING OVER WESTERN INDIANA AND ILLINOIS. RUC AND WATER VAPOR INDICATE A S/W OVER SOUTHERN MANITOBA. NAM/GFS INTENSIFY THIS S/W AS IT MOVS SOUTH TOWARDS THE MID MISSISSIPPI VALLEY LATE TONIGHT. NAM GIVES SEVERAL HUNDRETHS OF PRECIP LATE TONIGHT ACROSS CENTRAL INDIANA WHILE GFS HOLDS OFF ON PRECIP UNTIL IT MOVES PAST INDIANA. WILL MOVE TOWARD CONSENSUS AND PUT A 30 POP FOR THE EASTERN 2/3 OF THE CWA AS IT LOOKS LIKE SOME MEASURABLE PRECIP LOOKS POSSIBLE. AFTER S/W MOVS BY FLOW BECOME MORE NNW 850 MB TEMPERATUERS DROP TO -16 CELSIUS. THIS SHOULD RESLUT IN LAKE EFFECT SNOW SHOWERS ACROSS NORTHERN INDIANA AND SOME OF THIS SHOULD MOVE INTO OUR NORTHEAST COUNTIES FROM KOKOMO AREA EASTWARD. MET/MAV TEMPERATURES ARE PRETTY CLOSE AND SEEM REASONABLE BASED ON TEMPERATUERS UPSTREAM TODAY. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...THE LONG TERM PERIOD WILL CONSIST OF A SERIES OF CLIPPER LIKE SYSTEMS EVERY FEW DAYS. THE DIFFERENCES IN THE MODELS ARE MAINLY WITH MOISTURE AND QPF AMOUNTS BUT MOSTLY AGREE ON UPPER FEATURES. AT THIS POINT NONE OF THESE SYSTEMS APPEAR TO PRODUCE LARGE SNOW AMOUNTS AND INDIVIDUALLY WILL PROBABLY STAY AROUND AN INCH MAYBE SLIGHTLY OVER OR UNDER. WILL USE A BLEND. THURSDAY NIGHT...AS UPPER SYSTEM CLEARS THE STATE SOME LINGERING PRECIP IS POSSIBLE COURTESY OF LAKE MICHIGAN. HAVE PUT SOME CHANCE POPS IN THE EASTERN 1/3 OF THE CWA TO ACCOUNT FOR THIS. AFTER MIDNIGHT MOST OF THE PRECIP SHOULD HAVE CLEARED THE AREA. VERY COLD H85 TEMPS DIP INTO THE -10 TO -14C RANGE AND WITH SNOW ON THE GROUND OVERNIGHT LOWS WILL BE IN THE TEENS. FRIDAY...CENTRAL INDIANA IS IN BETWEEN SYSTEMS AND WILL REMAIN DRY. DAYTIME HIGHS WILL BE IN THE LOWER TO MID 30S AND LOWS IN THE MID 20S. SATURDAY...A COLD FRONT APPROACHES CENTRAL INDIANA ON SATURDAY AND WILL GENERATE SOME PRECIP ALONG/AHEAD OF THE FRONT. ITS POSSIBLE THAT SOMETIME ON SATURDAY AFTERNOON TEMPS WILL WARM ENOUGH FOR PRECIP TO BE RAIN INSTEAD OF SNOW BUT WILL CONTINUE WITH SNOW UNTIL GFS/NAM COME INTO BETTER AGREEMENT WITH TEMPS. AS THE COLD FRONT PASSES WE GET A REINFORCING SHOT OF COLD AIR WHICH WILL PUT LOWS BACK IN THE TEENS. ON SATURDAY NIGHT AN H5 WAVE PASSES THROUGH AND WILL KEEP CHANCE OF SNOW IN THE FORECAST. SUNDAY...ANOTHER UPPER WAVE FOLLOWS SATURDAYS COLD FRONT. THIS ROUND WILL AGAIN DROP SOUTH FROM MN/WI AND BRING ANOTHER ROUND OF SNOW. WITH STRONG COLD ADVECTION SKIES WILL BE LOW OVERCAST WITH SNOW SHOWERS POSSIBLE FOR MOST OF THE DAY. AS THE SYSTEM EXITS WILL HANG ON TO CHANCE POPS IN THE EASTERN 1/3 OF THE CWA. MONDAY...LOOKS LIKE ANOTHER IN BETWEEN DAY WITH RELATIVELY DRY CONDITIONS AND COLD TEMPS. THE GFS DEVELOPS A SFC LOW OVER SW MISSOURI ON MONDAY AFTERNOON AND MOVES IT ESE THROUGH THE EVENING. THIS COULD BRING A CHANCE OF PRECIP TO CENTRAL INDIANA. WILL NOT RAISE POPS FOR THIS TIME BUT WILL KEEP CURRENT SLIGHT CHANCE SINCE ITS LIKELY TIMING/STRENGTH WILL DIFFER IN SUBSEQUENT MODEL RUNS. TUESDAY AND WEDNESDAY...EACH DAY WILL BE DRY AND COLD AS HIGH PRESSURE FROM THE PLAINS MOVES SOUTH INTO THE OHIO VALLEY THEN EAST TOWARDS THE COAST. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ AVIATION...HAINES SHORT TERM...JH/SALLY LONG TERM...SALLY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 950 PM CST FRI JAN 26 2007 .UPDATE... SOME SIGNIFICANT CHANGES TO THE FORECAST THIS EVENING...LOW CLOUDS ARE JUST NOT FORMING AS MODELS RUNS HAD EARLIER INDICATED WOULD. NAM AND RUC MODEL 925-950MB RH INDICATING THAT WE SHOULD HAVE HAD SOME LOW CLOUD DEVELOPMENT ALONG AND BEHIND THE WEAK COLD FRONT MOVING THROUGH THE AREA THIS EVENING...BUT THIS SIMPLY HAS NOT MATERIALIZED. THE GFS IS USELES...THE LOW LEVEL RH IS TOO HIGH COMPARED TO THIS EVENINGS SOUNDING...AND IT HAS EVEN MORE LOW CLOUDS THAN THE OTHER TWO MODELS. THUS...HAVE PULLED THE CLOUD COVER FOR OVERNIGHT TONIGHT FROM THE FORECAST AREA. WE ARE GOING TO HAVE TO WAIT UNTIL THE CLOUD MASS NOW OVER NORTHERN AND CENTRAL MINNESOTA MOVES DOWN INTO THE FORECAST AREA. AT THE CURRENT RATE...IT SHOULD GET DOWN TO AROUND KDBQ AROUND 10Z...TO THE QUAD CITIES BY 14Z...AND THROUGH THE ENTIRE CWA BY 18Z. THIS IS MUCH FASTER THAN THE MODEL RH PROGS WOULD IMPLY...SO THIS FORECAST IS MORE OF A NOWCAST. AS FOR EFFECTS ON TEMPERATURES...WITH THE WINDS STAYING UP BEHIND THE SURFACE FRONT WE SHOULD NOT HAVE TOO MUCH RADIATIONAL EFFECTS TO BE CONCERNED ABOUT SO HAVE ONLY LOWERED MIN TEMPS TONIGHT A SMIDGE. THE EXTRA SUNSHINE IN THE AREA TOMORROW MORNING SHOULD HELP BOOST TEMPERATURES A LITTLE MORE...SO TWEAKED UP THE MAX TEMP SLIGHTLY. WILL LET THE MID CREW TAKE ANOTHER LOOK AT THIS AS THERE IS SOME POTENTIAL FOR MID 30S ACROSS THE SOUTH WHERE THE SUN LASTS THE LONGEST. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ LE ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 320 PM CST FRI JAN 26 2007 .DISCUSSION... THE MAIN CONCERN WITH THIS FORECAST PACKAGE WILL BE THE TIMING OF WHEN THE COLD FRONT IN SOUTHERN NEBRASKA WILL REACH OUR FORECAST AREA THIS EVENING AND THEN HOW THE SYSTEM MOVING OUT OF WEST TEXAS WILL AFFECT OUR SOUTHERN COUNTIES TONIGHT. THE NEXT ISSUE WILL BE THE TIMING OF THE WAVE MOVING INTO THE AREA NEXT WEEK. TONIGHT: LATEST SURFACE ANALYSIS CERTAINLY SHOWS WHAT A DIFFERENCE SNOW COVER CAN MAKE. CURRENTLY TEMPERATURES ARE IN THE MID 50S IN PRATT AND MEDICINE LODGE WITH MID 40S OVER SOUTH CENTRAL KANSAS. 20Z SURFACE ANALYSIS ALSO SHOWS A DECENT WIND SHIFT LINE PUSHING THROUGH SOUTHERN NEBRASKA. NOT MUCH IN THE WAY OF COOLING IS TAKING PLACE BEHIND THIS BOUNDARY WITH TEMPERATURES STILL IN THE MID 40S. THE DEEPER COLDER AIR STILL LOOKS LIKE IT IS LURKING IN CANADA. THE LATEST RUC BRINGS THIS BOUNDARY THROUGH CENTRAL KANSAS THIS EVENING AND SOUTH CENTRAL AND SOUTHEAST KANSAS AFTER MIDNIGHT. THE BOUNDARY WILL DEVELOP A BETTER THERMAL GRADIENT AS THE NIGHT PROGRESSES AS THE UPPER LEVEL WAVE IN WEST TEXAS MOVES INTO THE REGION. THIS WAVE WILL HELP ENHANCE THE LIFT AND FRONTOGENESIS ALONG THIS BOUNDARY MAINLY ACROSS SOUTH CENTRAL AND SOUTHEAST KANSAS TONIGHT. THE ONLY CONCERN IS THE MOISTURE. WE ARE NOT TOO KEEN ON HOW THE MODELS ARE HANDLING THE LOW LEVEL MOISTURE LATELY. THE REASON FOR THIS IS THE MODELS SEEM TO BE OVERESTIMATING DEWPOINTS DURING THE EVENING AND OVERNIGHT. THE REASON COULD BE DUE TO LATENT HEAT EFFECTS OF DEPOSITION WHICH WILL CAUSE OUR DEWPOINTS TO LOWER THIS EVENING AS WELL. SOUTHEAST KANSAS LOOKS LIKE IT HAS THE BEST CHANCE FOR SOME LIGHT SNOW OR LIGHT FREEZING RAIN SINCE THEY HAVE BEEN HAVING A LITTLE DEEPER MOISTURE AND THEY MAY SEE MORE LIFT ASSOCIATED WITH THE UPPER LEVEL COLD POCKET. THE AREA OF LIFT LOOKS PRETTY GOOD...BUT WITH DRIER AIR MOVING IN AT THE LOW LEVELS IT WILL BE A BRIEF EVENT (<6 HOURS). SATURDAY: WE SHOULD SEE SOME LIGHT SNOW OR FLURRIES DURING THE MORNING...FOLLOWED BY CLEARING SKIES...BUT IT WILL BE RATHER BREEZY. COULD STILL SEE SOME MELTING TOMORROW AS WELL. SATURDAY NIGHT-TUESDAY NIGHT: THE MODELS ARE CONTINUING TO ADVERTISE US IN A NORTHWEST FLOW REGIME THROUGH MUCH OF NEXT WEEK. THE GFS ENSEMBLES/ECMWF/UKMET ARE ALSO IN FAIRLY SIMILAR AGREEMENT IN BRINGING ANOTHER REINFORCING SHOT OF COOLER AIR INTO THE FORECAST ARE ON MONDAY AND MONDAY NIGHT. HOWEVER...THE MOISTURE WILL BE RATHER LIMITED. THEREFORE...WE WILL NOT INTRODUCE ANY POPS AT THIS TIME. WEDNESDAY-FRIDAY: WE DID NOT MAKE MANY SIGNIFICANT CHANGES AT THIS POINT...BUT THE MODELS ARE HINTING AT A DECENT WAVE MOVING DOWN THE NORTHERN PLAINS AND PUSHING INTO THE UPPER MIDWEST BY THE END OF THE WEEK. THIS FEATURE WILL SEND ANOTHER FRONTAL BOUNDARY THROUGH THE REGION AROUND TUESDAY NIGHT. THERE IS ALSO THE POTENTIAL FOR DECENT ISENTROPIC ASCENT/MOISTURE TRANSPORT AFTER THIS BOUNDARY PASSES THROUGH. THIS IS REFLECTED MORE FROM THE ECMWF...BUT WE WILL HAVE TO WATCH LATER RUNS TO SEE HOW THAT PANS OUT. COX && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 25 35 16 33 / 10 10 0 0 HUTCHINSON 24 35 15 33 / 10 10 0 0 NEWTON 25 35 15 31 / 10 10 0 0 ELDORADO 25 35 15 32 / 10 10 0 0 WINFIELD-KWLD 26 36 17 34 / 20 20 10 0 RUSSELL 20 33 12 31 / 0 10 0 0 GREAT BEND 22 34 14 32 / 0 10 0 0 SALINA 22 34 14 30 / 0 10 0 0 MCPHERSON 24 35 15 31 / 10 10 0 0 COFFEYVILLE 28 38 16 32 / 30 30 0 0 CHANUTE 27 36 15 31 / 20 20 0 0 IOLA 26 36 15 31 / 20 20 0 0 PARSONS-KPPF 28 37 16 32 / 20 30 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 245 AM MST THU JAN 25 2007 .DISCUSSION...FORECAST PROBLEMS WILL HOW WARM IT GETS TODAY... MAXES ON FRIDAY AHEAD OF THE FRONT...HOW MUCH IS THE COOL DOWN ON SATURDAY...AND A LOW CHANCE OF PRECIPITATION SATURDAY AND SATURDAY NIGHT. SATELLITE CONTINUING TO SHOW THE FLOW BECOMING MORE AMPLIFIED FROM THE CENTRAL PACIFIC INTO NORTH AMERICA. FLOW IS BLOCKED UP OVER THE ATLANTICE. STRONG SYSTEM HAS DEVELOPED JUST SOUTH OF THE ALEUTIANS AND HAS PUMPED UP THE RIDGE BEHIND THE TROUGH APPROACHING THE WEST COAST. SOUTHERN PORTION OF THE TROUGH BECOMING MORE CUTOFF WITH NORTHERN PORTION CRASHING INTO THE RIDGE. BROAD AND DRY RIDGE HAS BUILT OVER THE WESTERN HALF OF THE COUNTRY. SOUTHERN PORTION OF EASTERN TROUGH HAS CUT OFF OVER NORTHERN MEXICO. AT JET LEVEL...MODELS INTIALIZED FINE. HOWEVER...THERE WAS NOT A LOT OF SAMPLING WITH TROUGH APPROACHING THE NORTHERN CALIFORNIA COAST. AT MID LEVELS...SATELLITE SHOWING MODELS ARE IN VERY CLOSE AGREEMENT WITH ALL THE MAIN UPPER LEVEL FEATURES. REALLY ONLY ONE AREA WHERE MODELS MAY BE A LITTLE OFF. THIS IS WITH THE LOW OFF THE NORTHERN CALIFORNIA COAST. INITIALLY THEY MAY NOT HAVE BEEN FAR ENOUGH SOUTH WITH THE CENTER. THEN THE GFS/UKMET ARE TOO FAR SOUTH WITH IT. THE NGM/NAM/RUC ARE RIGHT ON WITH THE CENTER. AT LOW LEVELS...THE RUC13/NAM/ECMWF WERE HANDLING THE LEE TROUGH BETTER WITH THE RUC13/NAM NEARLY THE SAME WITH TIME. OVER THE AREA AND TO THE NORTH/NORTHWEST OF THE AREA...THE NAM/ECMWF WERE DOING A LITTLE BETTER THAN THE REST. THE UKMET WAS NOT TOO FAR BEHIND. MODELS ARE ALL OVER THE PLACE WITH EVOLUTION OF WHAT IS GOING TO HAPPEN ALONG THE WEST COAST AT UPPER LEVELS BUT ARE NOT TOO BAD FURTHER DOWNSTREAM. BASED ON RECENT PERFORMANCE AND CONSISTENCY... WILL USE A BLEND OF THE MODELS. WILL TREND MORE TOWARD THE UKMET AT MID/UPPER LEVELS...NAM/RUC13 AT LOWER LEVELS FOR BETTER INITIAL HANDLING OF LEE SIDE TROUGHING IN ADVANCE OF THE FRONT...AND PERSISTANCE WITH THE TEMPERATURES. TODAY/TONIGHT...WILL BE NO CLOUD COVER TODAY WITH BROAD RIDGE AND NO LIFT IN PLACE. MODELS ARE SHOWING THE SURFACE WINDS FOR THE DAY IN MORE NORTHWEST DIRECTION THAN THE PREVIOUS COUPLE OF DAYS WHICH HAD WINDS CLOSER TO SOUTHWEST. WILL STICK CLOSE TO THE 2 METERS/SOUNDINGS WHICH HAVE BEEN DOING THE BEST WITH THE SNOW FIELD IN PLACE. THIS MEANS ABOUT 10 DEGREES BELOW GUIDANCE. WARM AIR ADVECTION OCCURS DURING THE NIGHT IN ADVANCE OF THE FRONT WITH WARMEST TEMPERATURES POTENTIALLY IN THE EAST. FRIDAY/FRIDAY NIGHT...OVERNIGHT WARM AIR ADVECTION WILL MAKE FOR A RATHER WARM START TO THE DAY. MODELS DIFFER ON ARRIVAL TIME OF FRONT. NAM HAS SLOWED 3 TO 6 HOURS FROM YESTERDAY AND IS SIMILAR TO THE RUC13. THIS MEANS NOT BRINGING THE FRONT INTO THE NORTHWEST UNTIL THE 15Z TO 18Z TIME FRAME. UKMET/GFS ARE ABOUT THE SAME AND IN THE MIDDLE OF THE BUNCH. THE ECMWF IS THE FASTEST AND SIMILAR TO YESTERDAYS TIMING. THE NAM IS WARMEST AT 18Z. DESPITE THE SIMILAR TIMING...THE GFS IS MUCH MORE AGGRESSIVE IN BRINGING THE COLD AIR THAN THE UKMET. AND DESPITE THE TIMING DIFFERENCE...THE NAM AND ECMWF ARE ABOUT THE SAME BY 00Z. FRONTS HAVE A NACK IN COMING IN FASTER IN THIS SCENARIO. DID A SLIGHT TWEEK UP...ESPECIALLY IN EASTERN AND SOUTHERN LOCATIONS WHERE WILL HAVE THE WARMEST START AND LATEST FROPA. STILL TENDED TO STAY BELOW THE COOLEST NUMERICAL GUIDANCE AND CLOSE TO THE NAM 2 METER TEMPERATURES. NOT SURE ABOUT CLOUD COVER DURING THE NIGHT...BUT MINS MAY NEED TO BE COOLED MORE. SATURDAY/SATURDAY NIGHT...COLD AIR MASS IS POURING IN. COOLED OFF MAXES SOME AND CLOSER TO THE COOLER MET GUIDANCE. HOWEVER... MAY NEED TO COOL OFF THESE MORE THAN I HAVE. MOISTURE AND LIFT INCREASE IN THE WESTERN PORTION OF THE FORECAST AREA. THE BEST FRONTOGENETIC FORCING...SYNOPTIC SCALE LIFT...AND MOISTURE RESIDE IN COLORADO. HOWEVER...THETA E LAPSE RATES ARE NOT THAT IMPRESSIVE. ALSO...THE NAM HAS PULLED THE BEST MOISTURE A LITTLE FURTHER WEST ON THE 06Z RUN. SOME UPLSOPE LOOKS TO OCCUR IN THE FAR WEST AS WELL. ALSO DEPENDING ON WHICH MODEL YOU CHOOSE...THE RIGHT REAR QUADRANT OF THE JET STARTS AFFECTING THE FORECAST AREA IN THE AFTERNOON. THE GFS/UKMET ARE MORE FAVORABLE WITH THE NAM FURTHERN NORTH. THIS LIFT LASTS TO BETWEEN 06Z AND 12Z DURING THE NIGHT. SO INTRODUCE FLURRIES AND A SLIGHT CHANCE OF SNOW TO THE FAR WEST AND SOUTHWEST PORTION OF THE FORECAST AREA. THE BEST CHANCE LOOKS TO BE ALONG THE PALMER DIVIDE. AT THIS TIME...NO CHANGES PLANNED FOR DAYS 4 AND 5. THANKS TO ALL FOR THE COLLABORATION. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 922 PM CST FRI JAN 26 2007 .UPDATE... CLOUDS HAVE STILL YET TO MATERIALIZE ALONG THE COLD FRONT MOVING INTO NW MISSOURI AT 03Z. RUC MODEL REMAINS AGGRESSIVE WITH LOW LEVEL MOISTENING OVERNIGHT...ESPECIALLY RH FIELDS AT AND BELOW 925 MB. MODEL RH FROM MOST MODELS DOES NOT SEEM A RELIABLE INDICATOR OF LOW CLOUDS TONIGHT. BACKED OFF ON FORECAST CLOUDS OVERNIGHT. POST FRONTAL LOW CLOUDS SHOULD INCREASE SATURDAY. BUMPED TEMPS UP JUST A DEGREE OR TWO OVERNIGHT AS READINGS ARE NOT FALLING AS QUICKLY AS MODELS OR GRIDDED FORECASTS INDICATED. BRISK SOUTHWEST LOW LEVEL FLOW WILL CONTINUE MUCH OF THE NIGHT. && .PREV DISCUSSION... EARLY THIS AFTERNOON...HIGH PRESSURE WAS CENTERED OVER THE GULF COAST...WITH A COLD FRONT ANALYZED FROM WISCONSIN...ACROSS NW IOWA TO ERN NEBRASKA AND WRN KANSAS. SKIES WERE CLEAR ACROSS A LARGE PART OF THE NATION/S MID SECTION. THE CLOSEST OBSERVED CLOUD COVER OF CONCERN...WAS OVER TX AHEAD OF AN UPPER LEVEL LOW SEEN SPINNING OVER WEST TX. SO FOR TONIGHT...WILL START OFF FREE OF CLOUD COVER. THEN...FROM ABOUT MIDNIGHT ON...WILL INCREASE CLOUDS WITH THE APPROACH OF BOTH THE SURFACE COLD FRONT AND UPPER LEVEL LOW. A DECENT PRES GRADIENT SHOULD REMAIN ACROSS THE FA TONIGHT. SO WE EXPECT TEMPS TO STAY UP A BIT TONIGHT. USED A BLEND OF FWC/MAV/MET MOS. WILL MAINTAIN CHANCE POPS FOR PRECIPITATION SATURDAY AS THE ARCTIC FRONT MOVES ACROSS THE REGION...COINCIDENT WITH REMNANT UPPER LEVEL ENERGY ASSOC WITH DAMPENING UPPER WAVE THAT WILL MOVE ACROSS THE LOWER MISSISSIPPI VALLEY REGION FROM THE SOUTHERN PLAINS. PRECIP TYPE SHOULD BE RAIN INITIALLY. CAA AND LOWERING OF FREEZING LVL HEIGHTS FROM NORTH TO SOUTH MAY CHANGE THE PRECIP OVER TO SOME LIGHT SNOW BEFORE THE MOISTURE DEPARTS. CANNOT RULE OUT A BIT OF SLEET AS WELL. HOWEVER...QPF REMAINS LIGHT...AND THE MOISTURE AND FORCING DEPART FAIRLY QUICKLY SAT EVENING. THUS WE DO NOT EXPECT THIS EVENT TO BE OF MUCH CONCERN. WILL GO WITH MIDDAY HIGHS...AND SHOW TEMPS FALLING A BIT IN THE AFTERNOON IN THE WAKE OF THE FRONT. STRONG HIGH PRESSURE WILL CONTROL OUR WEATHER SUNDAY. SHOULD BE A FAIRLY COLD DAY WITH AN AIRMASS OF ARCTIC ORIGIN ACROSS THE FA. HIGHS WILL STRUGGLE TO REACH OR BARELY EXCEED 30 DEGREES. WE CANNOT RULE OUT A FEW FLURRIES ACROSS THE EVV TRI-STATE. WILL STAY IN NW FLOW PATTERN EARLY NEXT WEEK. THIS WILL RESULT IN PERIODIC CLOUDINESS AND TEMPS AT OR BELOW NORMAL. LONGWAVE PATTERN TAKES SHAPE OVER THE CONUS MID TO LATE WEEK. THE MODELS HAVE HAD ISSUES HANDLING TIMING AND INTENSITY OF FEATURES MOVING ALONG IN THE MID TROP. KEPT POPS LOW CHANCE CATEGORY MID TO LATE WEEK...UNTIL THE MODELS CAN LOCK INTO A SOLUTION. WILL KEEP THE PRECIP TYPE AS SNOW FOR NOW AS THE COLD AIR SHOULD STILL BE IN PLACE. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREV DISC...CN ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1230 AM EST THU JAN 25 2007 .AVIATION (06Z TAFS)... MAIN CONCERN OVER THE NEXT SEVERAL HOURS IS AREA OF SNOW DROPPING SOUTH OUT OF INDIANA. THIS SNOW WILL AFFECT SDF AND LEX TERMINALS THE MOST...PRIMARILY BETWEEN 09Z AND 16Z. BWG WILL CATCH A FEW FLURRIES FROM IT BUT THAT SHOULD BE ABOUT IT THERE. CEILINGS AND VISIBILITIES WILL GO MVFR...AND DURING THE HEIGHT OF THE SNOW SHOWERS AT SDF AND LEX WILL LIKELY DROP SLIGHTLY BELOW 2000 FEET. AS THE AXIS OF THE UPPER TROF RESPONSIBLE FOR THESE SNOW SHOWERS MOVES TO OUR EAST THE SNOW SHOULD EXIT AS WELL...BY MIDMORNING. WITH HIGH PRESSURE NOSING IN FROM THE WEST SKIES WILL MOSTLY CLEAR BY LATE MORNING AT SDF AND BWG. WILL KEEP THE CLOUDS IN AT LEX LONGER AS THE MOISTURE TAKES A BIT MORE TIME TO SCOUR OUT OF THAT AREA IN THESE NORTHWEST FLOW SITUATIONS PLUS SOME CLOUD ENHANCEMENT COMING OFF LAKE MICHIGAN. BY LATE AFTERNOON CLOUDS SHOULD BE GONE AND CLEAR SKIES WILL CONTINUE INTO THE EVENING. WINDS COULD GET A BIT GUSTY OUT OF THE NORTH TODAY AS THE GRADIENT TIGHTENS. 13 && .EVENING UPDATE... UPDATED EVENING FORECAST TO REFLECT CLOUD TRENDS. ALBERTA CLIPPER CURRENTLY SEEN ON WATER VAPOR SATELLITE CURRENTLY OVER WISCONSIN WILL DIVE SOUTHWARD AND MOVE ACROSS EASTERN KENTUCKY EARLY TOMORROW. MOISTURE IS LACKING AND AIR REMAINS UNSATURATED ABOVE 800 MB ACCORDING TO NAM CROSS SECTIONS. HOWEVER...STRONG COLD AIR ADVECTION WILL BEGIN IN EARNEST EARLY TOMORROW. AS LOW LEVEL LAPSE RATES STEEPEN...SCATTERED SNOW SHOWERS STILL EXPECTED TO DEVELOP ACROSS EASTERN INDIANA...AND MOVE ACROSS OUR NORTHEASTERN COUNTIES. HAVE PUSHED BACK THE POSSIBLE ONSET OF SNOW SHOWERS TO THE PRE-DAWN HOURS TO CORRESPOND WITH COLDER AIR`S ARRIVAL. SOME LIGHT LOCALIZED ACCUMULATIONS STILL POSSIBLE ACROSS THE BLUEGRASS REGION UNDER THE HEAVIER SHOWERS. TEMPERATURES WILL NOT RISE MUCH TOMORROW...AS BLUSTERY NORTHWEST WINDS WILL DEVELOP BY LATE MORNING AS COLDER AIR ARRIVES. JSD .SHORT TERM (TONIGHT-THURSDAY)... DUE TO CLIPPER SYSTEM...NE SECTIONS OF THE LMK CWA SAW MEASURABLE SNOW EARLY THIS MORNING...WITH AMOUNTS RANGING FROM A FEW TENTHS TO NEARLY 1.5 INCHES. NUMEROUS TRAFFIC ACCIDENTS OCCURRED DURING THE MORNING COMMUTE. TEMPERATURES HAVE RISEN ABOVE FREEZING...MELTING NEARLY ALL THE SNOW PER WEBCAMS. POWERFUL JET STREAK OVERHEAD TODAY...EARLIER 737 AIRCRAFT OBSERVATION AT FL380 NEAR SDF INDICATED A 183KT WESTERLY WIND (AND MODERATE TURBULENCE). FOCUS FOR THIS PERIOD IS ON YET ANOTHER CLIPPER SYSTEM FCST TO ROLL THOUGH THE DISTRICT THURSDAY. CURRENTLY FEATURE IS POSITIONED OVER WRN SECTIONS OF ONTARIO...AND IS FCST TO DROP QUICKLY FROM SRN INDIANA AT 12Z/THU INTO ERN KY BY 18Z/THU. AHEAD OF THIS UPPER WAVE FCST SOUNDINGS FROM GFS/NAM SHOW STEEPENING LAPSE RATES LATE TONIGHT AND THURSDAY WITH SATURATION INTO THE CRITICAL ICE CRYSTAL GENERATION LAYERS OVER NE 1/3 OF THE CWA...THOUGH GFS IS LESS AGGRESSIVE WITH SATURATION AS COMPARED TO THE NAM. SCT SHSN ARE EXPECTED OVER THE NRN/ERN ZONES FROM ROUGHLY 8Z TONIGHT THROUGH 15Z THURSDAY MORNING. WE WILL GO WITH 30-40% POPS FOR THIS AREA...LESSER VALUES OVER REMAINDER OF CWA INCLUDING MOST OF SRN KY...WHERE ONLY FLURRIES WILL BE MENTIONED. BUFKIT DIAGNOSTICS FROM WETTER NAM PRODUCE AROUND 0.5 INCH OF SNOWFALL FROM MADISON INDIANA SE INTO THE FFT/LEX AREAS... WITH AROUND 0.25 INCH AT SDF. THESE VALUES SEEM REASONABLE...THOUGH THEY WILL BE LOCALIZED DEPENDING ON EXACTLY WHERE SNOW SHOWERS DEVELOP. AN SPS WILL BE ISSUED FOR OUR FAR NE COUNTIES HIGHLIGHTING POTENTIAL FOR MORE SNOW...AND SIMILAR IN NATURE TO THIS MORNINGS ACTIVITY...IT HAS THE POTENTIAL TO AFFECT THE MORNING DRIVE TOMORROW. IN THE MEANTIME...CURRENT AREA OF LOW CLOUDS IS EXPECTED TO DISSIPATE AND/OR SLIDE SE SUCH THAT SKIES WILL GO PARTLY CLOUDY OR MOSTLY CLEAR OVER MUCH OF THE CWA FROM LATE AFTN INTO EARLY EVENING. THEN TOWARD 6Z LOW LEVEL RH FIELDS DEPICT CLOUDS RAPIDLY INCREASING INTO THE OVERNIGHT HOURS. REGARDING TEMPERATURES...HAVE FOLLOWED LATEST RUC PROJECTIONS FOR TONIGHT AND TOMORROW GIVEN IT`S RECENT GOOD PERFORMANCE. THIS YIELDS VERY SLOWLY FALLING TEMPS TONIGHT INTO THE UPPER 20S/LOWER 30S...WITH NEAR STEADY READINGS THURSDAY. STEEPENING LAPSE RATES WILL PROMOTE GUSTY WINDS THURSDAY...BUFKIT SUGGESTING GUSTS TO 20KTS OR SO POSSIBLE AND HAVE FOLLOWED THIS. CS .LONG TERM (THURSDAY NIGHT-WEDNESDAY)... THURSDAY NIGHT AND FRIDAY... COLD AIR ADVECTION WILL IN IN PLACE AT THE BEGINNING OF THIS FORECAST PERIOD WITH THE 8H ISOTHERM AT 00Z FRIDAY SOUTH OF THE FORECAST AREA. THIS IS IN THE WAKE OF A CLIPPER MOVING TO OUR SOUTHEAST. THIS CAA WILL BE SHORT LIVED AS THE NEXT CLIPPER SYSTEM BEGINS TO DROP SOUTH OUT OF CENTRAL CANADA. LOW LEVEL WINDS WILL BACK AND INCREASE FROM THE WEST FRIDAY AND A WARM FRONT WILL MOVE THROUGH THE AREA. BY 00Z SATURDAY H8 TEMPS WILL HAVE WARMED TO THE FREEZING MARK. SO AFTER A CLEAR AND COLD THURSDAY NIGHT...FRIDAY WILL BE BREEZY AND WARMER. TEMPERATURES FRIDAY MORNING WILL START OUT IN THE LOWER 20S BUT WITH THE WARMING READINGS WILL RISE INTO THE LOWER AND MID 40S BY AFTERNOON. SOUTHWEST WINDS FRIDAY NIGHT WILL KEEP TEMPERATURES IN THE 30S WITH INCREASING CLOUDS. SATURDAY THROUGH WEDNESDAY... A GREAT LAKES AND OHIO VALLEY UPPER LEVEL TROUGH WILL REMAIN IN PLACE THROUGH THIS FORECAST PERIOD. EXTENDED MODELS ARE IN AGREEMENT ON BRINGING SEVERAL DISTURBANCES THROUGH THE FLOW WHICH WILL BRING SOME ADDITIONAL LIGHT RAIN OR SNOW TO THE AREA AS WELL AS REINFORCING COLD AIR. THE FIRST WAVE WILL SHARPEN UP SATURDAY AND SLOWLY MOVE ACROSS THE REGION SUNDAY. WITH BACKING LOW LEVEL WINDS AHEAD OF THE DEEPENING TROUGH ENOUGH WARM AIR WILL FILTER INTO THE REGION TO PRODUCE LIGHT RAIN SATURDAY. COLDER AIR WILL OVERSPREAD THE LOWER OHIO VALLEY SATURDAY NIGHT SO ANY ADDITIONAL PRECIPITATION WILL BE IN THE FORM OF SNOW. WE WILL KEEP POPS IN THE LOW CHANCE CATEGORY BUT IF WE SEE PERSISTENCE IN THIS CLIPPER SYSTEM POPS WILL NEED TO BE RAISED ESPECIALLY OVER THE NORTHEAST PORTION OF THE FORECAST AREA. A SECOND WAVE WILL DIG INTO THE REGION TUESDAY WITH SOME VARIATION IN THE MODELS ON THE LOCATION AND STRENGTH. FOR NOW WE WILL FOLLOW THE GFS AND KEEP THE FORECAST AREA DRY. THE INITIAL SHOT OF COLD AIR SATURDAY NIGHT WILL DROP TEMPERATURES INTO THE 20S AND LOW 30S SUNDAY AND INTO THE TEENS AND 20S MONDAY WITH A SLIGHT WARM UP TUESDAY. COLDER TEMPERATURES WILL BE NOTED AGAIN WEDNESDAY AS THE SECOND CLIPPER MOVES TO THE SOUTHEAST. --JA && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PITTSBURGH PA 305 AM EST FRI JAN 26 2007 .SHORT TERM /TODAY THROUGH TONIGHT/... WITH NAM AND RUC MODEL RUNS CONTINUING TO SHOW LOW LEVEL WINDS BACKING INTO THE WEST THIS MORNING...AND THEN SOUTHWEST LATER TODAY, LINGERING LAKE EFFECT SNOW SHOWERS AFFECTING WESTERN PENNSYLVANIA WILL DISSIPATE BY DAYBREAK. THE ASSOCIATED WARMING WITH THE CHANGE IN WIND DIRECTION (WARM FRONT) WILL OCCUR MORE ALOFT, HENCE EXPECT STABILIZATION ABOVE THE BOUNDARY LAYER, PARTICULARLY THIS AFTERNOON AND EVENING. THIS STABILITY ALOFT IS FORTUNATE BECAUSE THERE WILL BE STRONG ISENTROPIC LIFT WITHIN THAT LAYER. THIS WILL WEAKEN THE EFFECTS OF THE LIFT, DYNAMICALLY AND MICROPHYSICALLY (AS TEMPERATURES IN THIS LAYER MAY BE WARMER THAN M10C RESTRICTING ICE NUCLEATION), AND DUE TO THE LOW LEVEL DRYNESS, ANY SNOW CRYSTALS THAT DO FORM MAY EVAPORATE PRIOR TO REACHING THE GROUND. HOWEVER DYNAMICS WITH ADVANCING WARM FRONT ARE SUFFICIENT TO ESCALATE POPS OVER THE EASTERN ZONES BACK TO CHANCE NUMBERS BY THIS AFTERNOON, ALTHOUGH WORDING WILL BE FOR LIGHT SNOW WITH MINIMAL/NO ACCUMULATION. && .LONG TERM /SATURDAY THROUGH THURSDAY/... CONTINUE TO EXPECT THE COLD UPPER LOW TO REMAIN OVER EASTERN CANADA THIS WEEK, AS INDICATED BY RECENT GFS AND ECMWF MODEL RUNS. THIS WILL RESULT IN THE PASSAGE OF SEVERAL ARCTIC-TYPE COLD FRONTS THROUGH THE UPPER OHIO VALLEY THIS COMING WEEK. SO ALTHOUGH SATURDAY WILL EXHIBIT WARMER THAN NORMAL TEMPERATURES, EXPECT A RENEWAL OF COLDER TEMPERATURES STARTING SUNDAY WITH THE NEXT COLD FRONTAL PASSAGE, WITH TEMPERATURES PERHAPS A LITTLE COLDER THAN WHAT GFS MOS VALUES INDICATE. THERE WILL ALSO BE A COUPLE PESKY PERIODS OF SNOW SHOWERS THIS WEEK WITH THE FRONTAL PASSAGE AND ENSUING NORTHWEST LOW LEVEL FLOW OF COLD, LAKE-MOISTENED AND UNSTABLE AIR, PARTICULARLY SUNDAY, TUESDAY, AND THURSDAY. && .AVIATION... EXPECT MAINLY VFR CONDITIONS TODAY AND TONIGHT. THE MAIN CULPRIT FOR LOWERED CONDITIONS, POTENTIALLY TO IFR, PRIOR TO 12Z WILL BE ISOLATED SNOW BANDS. ONCE THE LOW LEVEL WINDS SWITCH INTO THE SOUTHWEST, THESE WILL BE GONE. ISENTROPIC LIFT ABOVE THE BOUNDARY LAYER WILL HELP FORM A STRATOCUMULUS DECK (OVC040), HOWEVER SNOW FORMATION WILL BE LIMITED BY THE STABILITY WITHIN THE LIFT ZONE AND LOW LEVEL DRYNESS UNDERNEATH. AS MENTIONED, WIND DIRECTIONS WILL GO FROM WEST PRIOR TO 12Z TO SOUTHWEST 12Z-20Z, TO NEAR SOUTH TONIGHT. SPEEDS WILL BE GENERALLY 5-10 KTS. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ 11/15 md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1030 PM EST FRI JAN 26 2007 .UPDATE... RADAR INDICATED AN BAND OF LIGHT SNOW OR FLURRIES BRUSHING NRN UPR MI ASSOCIATED WITH A LEAD SHRTWV AHEAD OF THE MID LVL LOW OVER WRN ONTARIO. AT THE SFC...THE OCCLUDED FRONT HAD MOVED INTO ERN UPR MI TO NEAR KERY. ISENTROPIC ASCENT AHEAD OF THE FRONT THAT HELPED SUPPORT -FZDZ EARLIER THIS EVENING HAS ALSO DEPARTED TO THE EAST. AS CAA INCREASES LATE 850 MB TEMPS ARE FCST TO DROP TO -12C TO -14C OVER THE WEST. THE COLDER AIR ALONG WITH MODERATE 700-500 MB QVECTOR CONV AHEAD OF THE NEXT SHRTWV...SHOULD BRING AN INCREASE IN SNOW/LES IN LINE WITH THE GOING FCST. THE SHRTWV ALSO WARRANTS KEEPING LIGHT SNOW CHANCES (20-40 POPS) GOING LATE TONIGHT FOR THE REST OF THE CWA WITH MINIMAL IF ANY ACCUMULATION. .SYNOPSIS... WATER VAPOR LOOP SHOWS AN UPSTREAM SHORTWAVE OVER WRN ONTARIO/NRN MN WITH A SECONDARY SHORTWAVE PINWHEELING THROUGH CENTRAL MANITOBA/SASKATCHEWAN. DOWNSTREAM FROM SHORTWAVES...MID-LVL RDG OVER THE UPPER GREAT LAKES HAS RESULTED IN MOSTLY DRY CONDITIONS ACROSS MUCH OF THE FCST AREA...EXCEPT FOR SOME UPSLOPE FLURRIES/PATCHY -FZDZ OVER PORTIONS OF CENTRAL AND ERN COUNTIES. BASED ON LATEST RADAR LOOP AND SFC OBS LOOKS LIKE ANY LINGERING LAKE EFFECT SNOW OVER SCHOOLCRAFT COUNTY IS WANING DESPITE DECENT LOW-LEVEL CONVERGENCE ALONG SFC TROF THERE. SO WILL CANCEL SNOW ADVISORY FOR SRN SCHOOLCRAFT COUNTY. .SHORT TERM (TONIGHT)... SHORTWAVE OVER WRN ONTARIO IS EXPECTED TO DIVE ACROSS LAKE SUPERIOR TONIGHT AS BEST FORCING FROM THIS FEATURE WILL BE NE OF CWFA. SHORTWAVE WILL DRIVE SFC TROF NOW OVER FAR WRN UPR MI ACROSS THE REST OF THE FORECAST AREA LATER THIS EVENING INTO THE EARLY OVERNIGHT. WIND SHIFTING TO A MORE WNW DIRECTION BEHIND THE TROF SHOULD BRING SOME LES FLURRIES INTO WRN AND PERHAPS INTO CENTRAL COUNTIES AS WELL...BUT AGAIN DO NOT EXPECT ANYTHING MORE THAN FLURRIES GIVEN MARGINALLY COLD 850 MB TEMPS (-9/-10C) AND FAIRLY STRONG SUBSIDENCE INTO THIS EVENING. KEPT IN A MENTION OF LIGHT SNOW OR PATCHY -FZDZ OVER THE KEWEENAW AND ERN HALF COUNTIES WHERE UPSLOPE S-SE FLOW WILL BE PRESENT ALONG SFC TROF AND WEAK FORCING IS POSSIBLE AHEAD OF INCOMING SHORTWAVE. AFTER MIDNIGHT...SECONDARY SHORTWAVE APPROACHES WITH BETTER SHOT OF CAA AS 850 MB TEMPS BEGIN TO LOWER TO -14/-16C OVER THE WRN FCST AREA. INCREASINGLY CYCLONIC/CONVERGENT NW FLOW AND MORE FAVORABLE SNOW GROWTH WILL FAVOR NRN GOGEBIC COUNTY THROUGH SRN HOUGHTON COUNTIES FOR BURSTS OF MORE INTENSE SNOW TOWARD MORNING WITH ACCUMULATIONS OF 1 TO 2 INCHES. .LONG TERM (SATURDAY THROUGH FRIDAY)... THE MAIN FORECAST CONCERN WAS THIS WEEKEND AND THE INHERITED LAKE EFFECT SNOW WATCHES...AS SOME DECISIONS NEEDED TO BE MADE ON UPGRADES OR DOWNGRADES. LAKE EFFECT SNOW ADVISORIES WERE ALSO NEEDING TO BE POSTED FOR PORTIONS OF THE CWA. AS ON THE FENCE WITH A FEW OF WSW ISSUES THIS FORECAST ISSUANCE. THE FIRST HAS TO DO WITH PORTIONS OF NORTHWESTERN HOUGHTON COUNTY...WHERE WARNING CRITERIA IS EXPECTED TO BE CLOSE. THE SECOND WAS WITH DELTA COUNTY...WHICH WOULD ALSO BE CLOSE TO THE 12 HOUR ADVISORY CRITERIA OF 3 TO 6 INCHES...PARTICULARLY ACROSS THE EXTREME NORTHERN SLIVER OF THE COUNTY. DECIDED TO GO WITH THE ADVISORY THERE. THE THIRD THING WOULD BE WITH RESPECT TO NORTHERN KEWEENAW COUNTY...AS WINDS INCREASE OUT OF THE NORTH LATE SATURDAY AFTERNOON INTO EARLY SUNDAY MORNING...AND GET CLOSE TO BLOWING SNOW ADVISORY CRITERIA. FOR THIS...HAVE ADDED THE MENTION OF LOCALIZED BLOWING SNOW TO THE WSW. THE SFC LOW (DOUBLE BARREL LOW CONFIGURATION) CURRENTLY STRETCHING FROM SOUTHWEST ONTARIO TO NORTHERN WISCONSIN WILL CONTINUE TO SLOWLY SLIDE SOUTHEASTWARD OVER LAKE SUPERIOR OVERNIGHT TONIGHT...AND THEN STRETCH FROM SOUTHEASTERN LAKE SUPERIOR TO SOUTHERN LAKE HURON BY 12Z SATURDAY. THIS WILL BEGIN TO TURN OUR WINDS TO A MORE FAVORABLE N-NW DIRECTION QUICKEST WEST 09Z AND 18Z CENTRAL...AND 850 TEMPS OF -4C AT 12Z THIS MORNING OFF OF THE INL SOUNDING WILL BE ALLOWED TO FALL A BETTER LAKE EFFECT TEMPERATURE OF -10C BY 06Z SATURDAY ACROSS THE LAKE SUPERIOR SHORELINE...COOLING OFF TO -12 TO -15C BY 12Z SATURDAY...WITH STILL LITTLE IN THE WAY OF AN INVERSION TO SPEAK OF. FOR QPF AMOUNTS...MADE FEW ADJUSTMENTS...STILL LINING UP CLOSER TO THE RUC13 AND REGIONAL CAN. FOR SATURDAY...TEMPS LOOK GOOD FOR SATURDAY AFTERNOON...WITH GUIDANCE CLUSTERED AROUND OUR INHERITED VALUES...SEE NO NEED TO MAKE ANY DRASTIC CHANGES. FOR MONDAY AND MONDAY NIGHT...TEMPERATURES DURING THE DAY MONDAY BECOME TRICKY. PLENTY OF COLD AIR WILL BE OVERHEAD...MODERATING BY A COUPLE OF DEGREES C AT 850MB WHEN COMPARED TO SUNDAY. HIGH CLOUDS WILL ALSO BE SLIDING IN DURING THE DAYTIME HOURS IN OUR NORTHWESTERLY FLOW OUT AHEAD OF OUR NEXT SYSTEM. ENDED UP HEDGING THE TEMPS SLIGHTLY TOWARDS THE GFS...WHICH IS ONE OF THE WARMER MODELS GUIDANCE WISE AT THAT TIME. IN TERMS OF WEATHER AND POPS MONDAY NIGHT INTO TUESDAY...START OUT THE NIGHT WITH NNE WINDS WHICH WOULD FAVOR JUST KEEPING POPS ACROSS THE EASTERN THIRD NEAR LAKE SUPERIOR...WITH A DRYING TREND ELSEWHERE. SHORTWAVE TROUGH SHOULD BE OVER NORTHERN AND CENTRAL NORTH DAKOTA MONDAY MORNING...AND THEN PUSH WELL TO OUR SOUTH AND OVER SOUTHWESTERN WISCONSIN BY 06Z TUESDAY. MUCH OF THE ENERGY ASSOCIATED WITH IT REMAINING TO OUR SOUTH AS WELL...LEAVING THE UPPER PENINSULA TEMPORARILY BETWEEN SYSTEMS. HAVE OPTED TO LOWER POPS ACROSS MUCH OF THE REGION...BUT STILL KEEPING 30-40 POPS FOR THE MORE FAVORED EASTERN THIRD. TAKING A LOOK AT THE GFS ENSEMBLES...THE OPERATIONAL GFS MAY BE ONE OF THE FURTHEST SOUTH OPTIONS FOR THE TROUGH...LEAVING SOME UNCERTAINTY IN PLAY FOR MONDAY NIGHT INTO TUESDAY. EVEN WITH THIS SAID IT SEEMS TO BE BACKED BY SOME OF THE OTHER GLOBAL MODELS INCLUDING THE ECMWF. AS FOR THE EXTENDED (TUESDAY THROUGH FRIDAY... ACTUALLY WARMED UP TEMPERATURES SLIGHTLY FOR DAYS 6 AND NEW 7 (THURSDAY AND FRIDAY)...UTILIZING LATEST HPC GUIDANCE FOR THAT PERIOD. IN FACT WENT ABOUT 5 DEGREES WARMER...PARTICULARLY ACROSS THE EASTERN HALF OF THE CWA FOR WEDNESDAY NIGHT AND THURSDAY AFTERNOON. OTHERWISE THROUGH THIS PERIOD...FEW CHANGES WERE MADE TO THE INHERITED FORECAST...AS EXTENDED GUIDANCE FOR OUR REGION CONTINUES TO BE FAIRLY WELL IN LINE FOR MUCH OF THIS TIME PERIOD. HPC UTILIZED THE 00Z ECMWF FOR THE START OF THE FORECAST PERIOD...AND TRANSITIONED TO THE 00Z NCEP ENSEMBLE MEAN. ZONAL FLOW WEDNESDAY...BUT WITH LINGERING MOISTURE HAVE NOT YET BEEN ABLE TO TAKE POPS OUT OF THE FORECAST. NEXT 500MB TROUGH DIGS IN WEDNESDAY NIGHT INTO THURSDAY. HAVE INCREASED THE POSSIBILITY OF SYNOPTIC SNOW FOR THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FROM 1 PM SATURDAY TO 1 AM EST MONDAY FOR MIZ004>006. LAKE EFFECT SNOW WARNING FROM 7 AM EST /6 AM CST/ SATURDAY TO 7 PM EST /6 PM CST/ SUNDAY FOR MIZ002-009. LAKE EFFECT SNOW ADVISORY FROM 10 AM SATURDAY TO 10 PM EST SUNDAY FOR MIZ001-003. LAKE EFFECT SNOW ADVISORY FROM 1 PM SATURDAY TO 1 AM EST MONDAY FOR MIZ013-085. && $$ .SHORT TERM...KF .LONG TERM...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1005 PM EST FRI JAN 26 2007 .UPDATE...1000MB SURFACE LOW NEAR TVC...WITH WIDESPREAD LOW CLOUDS TO THE EAST...NORTH...AND WEST. MOISTURE WAS DEEPER TO THE NE AND SHALLOWER TO THE SE. THE COLLISION/COALESCENCE WAS ACTIVE ENOUGH OVER THE NE 2/3DS OF THE FORECAST AREA TO PRODUCE LIGHT PRECIP. THIS WAS STILL SNOW OVER PARTS OF WESTERN CHIP/MACK COUNTIES...BUT OTHERWISE PRECIP WAS FALLING AS FZDZ. SAULT MI JUST WENT OVER FROM SNOW TO FZDZ IN THE PAST HOUR. KAPX 00Z SOUNDING WAS A CLASSIC DRIZZLE SOUNDING...ENTIRELY AT OR WARMER THAN -10C AND WITH A NICE MOISTURE SPIKE JUST ABOVE THE 825MB INVERSION. PRECIP AND HEADLINE TRENDS ARE THE MAIN CONCERNS FOR OVERNIGHT. IN EASTERN UPPER...GIVEN CURRENT REPORTS/OBS AN ADVISORY IS IN ORDER. FZDZ WILL END 1ST UP HERE...AS COOLER AIR GETS ADVECTED IN ON NW FLOW AS INITIAL SURFACE LOW MOVES OUT ACROSS HURON...JUST AHEAD OF SECONDARY CLIPPER NEARING EASTERN SUPERIOR. SUSPECT THAT FZDZ WILL WRAP UP BY 5-6AM...BUT TO BE SAFE WILL RUN THRU 8 AM (LIKE NORTHERN LOWER...SEE BELOW). IN NORTHERN LOWER...FZDZ HAS MADE AN UNFORTUNATE PUSH TO THE WEST/SW AS SURFACE LOW PASSES...PROBABLY A RESPONSE TO THE ADDED LOW LEVEL CONVERGENCE NEAR THE LOW DEEPENING THE MOIST LAYER. WILL ADD A HANDFUL OF COUNTIES...INCLUDING TVC/HTL...BACK INTO THE WINTER WX ADVISORY...AND EXTEND THRU 8 AM. AGAIN...THE ARRIVAL OF COOLER AIR SHOULD TRANSITION PRECIP TO SNOW VERY LATE TONIGHT. && .PREV DISCUSSION ISSUED 639 PM FRI JAN 26... UPDATE...OBS/RADAR TRENDS/CALLS TO LAW ENFORCEMENT INDICATE DZ/FZDZ IS VERY LIGHT TO NONEXISTENT IN THE SW AND FAR SOUTHERN ZONES. LOW LEVEL MOISTURE IS SHALLOWER AS YOU HEAD SW...LARGELY BELOW 800MB THERE VS UP TO 750MB OR SO IN APN AND THE STRAITS. WILL TAKE A STAB AT LOWERING THE WINTER WX ADVISORY FOR LEELANAU/TVC/HTL/STANDISH. WILL OBVIOUSLY MAINTAIN FURTHER NORTH...WHERE WIDESPREAD AND SUBSTANTIAL FZDZ HAS REDEVELOPED. ZOLTOWSKI DISCUSSION...MID AFTERNOON SATELLITE/SURFACE/RADAR/AND RUC ANALYSIS SHOW BASIC MID LEVEL CONFIGURATION OF THE LAST SEVERAL DAYS (AND FOR MANY MORE DAYS TO COME...SEE EXTENDED DISCUSSION BELOW) REMAINING IN PLACE WITH WESTERN NOAM LONG WAVE RIDGE AND SUBSEQUENT DOWNSTREAM CENTRAL AND EASTERN CONUS TROUGH. EASTERN CONUS TROUGH ABOUT TO BE REINFORCED AS VIGOROUS NORTHERN STREAM SHORTWAVE...AND ASSOCIATED HEIGHT FALLS...IS DIVING SOUTHEAST ACROSS CENTRAL MANITOBA. AT THE SURFACE...ELONGATED 999MB LOW PRESSURE EXTENDS FROM WESTERN ONTARIO TO NORTHERN WISCONSIN. SURFACE WARM FRONT EXTENDING EAST FROM THE LOW OVER NORTHERN MICHIGAN RACING OFF TO THE NORTHEAST AS LOW AND MID LEVEL WAA ADVECTION CONTINUES TO STRENGTHEN AHEAD OF SYSTEM. FARTHER WEST...FIRST IN A SERIES OF COLD FRONTS USHERING IN PROGRESSIVELY COLDER AIR EXTENDS FROM EASTERN PLAINS SOUTHWEST THROUGH THE CENTRAL PLAINS. REGIONAL RADAR PLOTS SHOW WHAT REMAINS OF THIS MORNINGS FRONTOGENETICALLY FORCED SNOWFALL SLIDING EAST OVER EASTERN LAKE HURON. WITH BEST DYNAMICS AND MID LEVEL MOISTURE PULLING OFF TO THE EAST...NORTHERN LOWER MICHIGAN SEEING WIDESPREAD AREAS OF LIGHT FREEZING DRIZZLE AND FINE SNOWFLAKES WITH BULK OF REMAINING MOISTURE REMAINING BELOW -10C...PER 12Z MODEL POINT SOUNDINGS. FORECAST CONCERNS TONIGHT CENTER ON FREEZING DRIZZLE POTENTIAL THIS EVENING WITH SNOWFALL POTENTIAL TAKING CENTER STAGE LATER TONIGHT. TONIGHT...12 MODEL SUITE IN EXCELLENT AGREEMENT SHOWING MANITOBA SHORTWAVE CONTINUE TO SLIDE SOUTHEAST...TO A POSITION AT THE NORTHEAST END OF LAKE SUPERIOR BY MORNING. ASSOCIATED SURFACE LOW TRACKS RIGHT ACROSS NORTHERN MICHIGAN OVERNIGHT...WITH TRAILING COLD FRONT CLEARING THE AREA TOWARDS MORNING. ALTHOUGH SURFACE SYSTEM SLIDES THROUGH THE HEART OF THE AREA...BEST MID AND UPPER LEVEL SUPPORT FOR SYNOPTIC PRECIPITATION REMAINS NORTH OF THE REGION...CLOSER TO THE SHORTWAVE. MODEL POINT SOUNDINGS FOR THE NORTHERN LOWER CONTINUE TO SUPPORT FREEZING DRIZZLE THROUGH THIS EVENING WITH LIMITED MID LEVEL MOISTURE...SATURATED CONDITIONS BELOW -10C...AND SOME WEAK SHEAR AT TOP OF INVERSION. FARTHER NORTH...EASTERN UPPER MORE MARGINAL ACCORDING TO SOUNDINGS AND WILL MENTION SNOW SHOWER/FREEZING DRIZZLE MIX WITH LESS ICE ACCUMULATION EXPECTED. ALSO SOME CONCERN ALONG THE SAINT MARYS RIVER OF SOME SOUTHEAST FLOW LAKE HURON ENHANCEMENT WITH EVENING DELTA T/S IN THE LOW TEENS. SOME EVIDENCE OF THIS ALREADY OCCURING WITH THE SOO REPORTING LIGHT SNOW FOR SEVERAL HOURS DESPITE DYNAMICAL FORCING NOW WELL OFF TO THEIR NORTHEAST. LAST FEW SCANS OF MONTREAL RIVER CANADA RADAR SHOWS EXPANDING AREA OF LIGHT SNOW AT THE NORTHWEST END OF THE NORTH CHANNEL...WHICH ALSO MIGHT BE A SIGN OF SOME LAKE ENHANCEMENT KICKING IN. HAVE LEFT LIKELY POPS THIS EVENING TO ACCOUNT FOR THIS WITH ACCUMULATIONS UP TO AN INCH RIGHT ALONG THE RIVER SYSTEM. AFTER MIDNIGHT...WEST TO WEST NORTHWEST FLOW CAA KICKS IN WITH 850MB TEMPERATURES DROPPING TO -11C TO -12C OVER NORTHERN LAKE MICHIGAN AND EASTERN LAKE SUPERIOR. MID LEVEL COOLING COMBINED WITH SOME SCOURING OUT OF LOW LEVEL MOISTURE SHOULD PUT AN END TO THE FREEZING DRIZZLE THREAT. FOCUS THEN SHIFTS TO LAKE EFFECT/ENHANCED SNOW POTENTIAL AS DELTA T/S DROP TO RIGHT AROUND 13C. BUFKIT AND POINT SOUNDING ANALYSIS SHOWS INVERSION LEVELS OF ONLY ABOUT 3.5KFT AND 850MB-700MB MOISTURE <50 PERCENT OVER NORTHERN LAKE MICHIGAN AND >70 PERCENT OVER EASTERN LAKE SUPERIOR. DID TRIM POPS SOME IN FAVORED WEST NORTHWEST FLOW AREAS OF THE NORTHERN LOWER. KEPT POPS IN HIGH CHANCE CATEGORY NEAR WHITEFISH POINT WITH LONGER FETCH LENGTH AND BETTER MID LEVEL MOISTURE. MARINE...COMPLICATED MARINE FORECAST OVERNIGHT AS WINDS VEER AROUND NORTHWESTERLY. WILL LEAVE CURRENT SCA FOR SELECTED NEARSHORE WATERS OF LAKE HURON AND MICHIGAN THROUGH THIS EVENING TO ACCOUNT PRIMARILY FOR GUST SOUTH TO SOUTHEAST WINDS. AFTER A LULL LATER THIS EVENING...WINDS WEST NORTHWEST WINDS PICK UP OVER NORTHERN LAKE MICHIGAN. HAVE GONE AHEAD AND ADDED NORWOOD MICHIGAN TO THE BRIDGE NEARSHORE ZONE TO THE LAKE MICHIGAN GROUP TO ACCOUNT PRIMARILY FOR WAVES. WILL LET LAKE HURON NEARSHORE WATERS EXPIRE AS WIND FIELDS TAKE LONGER TO ORGANIZE. MSB LATER PERIODS...ACTIVE PERIOD SHAPING UP AS A SERIES OF CLIPPERS WILL TRAVERSE ACROSS THE NORTHERN GREAT LAKES. FIRST OF THESE SYSTEMS WILL ARRIVE ON SATURDAY AFTERNOON WITH A SECOND CLOSE BEHIND IT MOVING IN ON SUNDAY. THIS WILL SET THE STAGE FOR A PERIOD OF ACCUMULATING LAKE EFFECT SNOWS FOR EASTERN UPPER AND NORTHWEST LOWER MICHIGAN. THIS LATTER SYSTEM WILL ALSO BRING A SURGE OF BELOW NORMAL TEMPERATURES...WHICH LOOKS ONLY TO BE A PRECURSOR OF WHAT IS TO COME LATER NEXT WEEK. OTHER CLIPPERS TAKE AIM ON THE GREAT LAKES ON TUESDAY AND THURSDAY. THE LAST IN THE SERIES OF WAVES COULD POTENTIALLY BRING SOME OF THE COLDEST AIR IN YEARS TO THE GREAT LAKES FOR NEXT WEEKEND AS AIR ORIGINATING DIRECTLY OUT OF THE NORTH POLE DIVES SOUTH. MODELS IN GENERAL HAVE A PRETTY GOOD HANDLE ON THE OVERALL FLOW PATTERN OVER THE NEXT 7 DAYS. HAVE MOSTLY USED A BLEND OF THE GFS AND ECMWF...AND HAVE MIXED IN A LITTLE OF THE NAM THROUGH ABOUT 48 TO 60 HOURS OUT. TOMORROW...STRONG SHORTWAVE AS SEEN ON WV IMAGERY OVER MANITOBA WILL PASS ACROSS THE CWA WITH THE BEST FORCING ARRIVING ACROSS LOWER MICHIGAN DURING THE AFTERNOON. AS THE SHORTWAVE APPROACHES...850-700MB RH VALUES BECOME NEARLY SATURATED AND INVERSION HEIGHTS INCREASE FROM 4KFT AT 12Z TO 7KFT BY 00Z SUN. 850MB TEMPERATURES START OUT MARGINAL FOR LAKE EFFECT BETWEEN -10C AND -12C CREATING DELTA T`S AROUND 13C TO 15C...BUT COLD ADVECTION OVER THE COURSE OF THE MORNING WILL CREATE A MORE FAVORABLE THERMODYNAMIC PROFILE FOR LAKE EFFECT (DELTA T`S INCREASE BY A COUPLE DEGREES BY 18Z AND A COUPLE DEGREES MORE BY 00Z). SECONDARY COLD FRONT APPROACHES THE SOUTH SHORE OF LAKE SUPERIOR BY 00Z...WHOSE ADDED CONVERGENCE WILL HELP BOOST ONGOING LAKE EFFECT SNOW. BECAUSE OF THE INCREASINGLY FAVORABLE CONDITIONS FOR SNOW DURING THE AFTERNOON...WILL KEEP CHANCEY TO LIKELY ACROSS LAKE EFFECT PRONE AREAS DURING THE MORNING HOURS...AND CATEGORICAL OVER THESE SAME AREAS FOR THE AFTERNOON. SNOW AMOUNTS WILL PROBABLY IN THE 1-3 INCH RANGE FOR THE LAKE EFFECT AREAS NEAR WHITEFISH POINT AND THE TYPICAL CORRIDOR ACROSS NORTHWEST LOWER. SATURDAY NIGHT INTO SUNDAY... LEADING SHORTWAVE WILL MOVE SOUTHEAST AND CLEAR THE CWA DURING THE EVENING HOURS. HOWEVER...SECONDARY SHORTWAVE WILL MAINTAIN THE CYCLONIC FLOW OVER THIS PERIOD AND DRIVE AN ARCTIC FRONT SOUTH OVERNIGHT. GFS HAS BEEN TRENDING SLOWER WITH THE FRONTAL PASSAGE...MORE IN LINE WITH THE NAM OVER THE PAST COUPLE DAYS. STRONG COLD ADVECTION ENSUES BEHIND THIS FRONT AS WNW WINDS SHIFT TO THE NNW OR DUE NORTH DIRECTION AND WILL USHER IN 850MB TEMPS BELOW -20C. IN ADDITION...MODEL 850-700MB RH FIELDS KEEP PLENTY OF MOISTURE WITHIN THIS CYCLONIC FLOW...WHILE INVERSION HEIGHTS REMAIN HIGH ACROSS NORTHWEST LOWER (ABOVE 6KFT) BUT DECREASE ACROSS EASTERN UPPER ON SUNDAY SINCE UPPER LEVEL TROUGHING WILL BE EXITING HERE FIRST. THIS APPEARS TO BE A PRETTY GOOD SETUP FROM A LAKE EFFECT STANDPOINT WITH SHARP LOW LEVEL CYCLONIC FLOW ACROSS THE REGION TO ENHANCE CONVERGENCE. WITH THE LOW LEVEL FLOW OUT OF THE NORTHEAST FOR A GOOD PORTION OF THE NIGHT ACROSS EASTERN UPPER...AND ONSHORE NW TO N FLOW ACROSS NORTHWEST LOWER (WITH THE STRONGEST FORCING)...EXPECT THE HIGHEST ACCUMULATIONS TO OCCUR ACROSS NORTHWEST LOWER AND WILL REFLECT THIS IN THE GRIDS. HAVE THOUGHT ABOUT A PUTTING UP A LAKE EFFECT SNOW WATCH...BUT UNCERTAINTY WITH THE FRONTAL PASSAGE TIMING AND THE CORRESPONDING VEERING OF WINDS HAS MADE IT QUITE DIFFICULT TO PINPOINT AN AREA WHICH CAN CONFIDENTLY SAY WILL GET THE MOST SNOW. WILL ALSO HAVE TO WATCH FOR ACCUMULATING SNOW ACROSS NE LOWER OVERNIGHT INTO SUNDAY MORNING WITH THE SHARP NE FLOW IN PLACE. SUNDAY NIGHT INTO MONDAY...UPPER LEVEL TROUGH REMAINS IN PLACE OVERNIGHT WITH DRIER AIR MOVING IN AS THE NIGHT WEARS ON. WITH THE UPPER TROUGH EXITING...1000-850MB WINDS BACK FROM THE NNW TO WNW WITH 850MB TEMPERATURES (-20C) HARDLY WARMING WHATSOEVER...AND INVERSION HEIGHTS WILL FALL THROUGH THE DAY. THEREFORE...BELIEVE THE ONGOING LAKE EFFECT SNOW SHOWERS WILL DIMINISH THROUGH THE PERIOD SO WILL KEEP HIGHER POPS (LIKELY) GOING FOR SUNDAY NIGHT AND LOWER POPS (CHANCE) FOR WNW FLOW AREAS ON MONDAY. NEXT CLIPPER SYSTEM DIVES SE OVER THE NORTHERN PLAINS ON MONDAY. TIMING OF THIS SYSTEM STILL A LITTLE SUSPECT WITH THE ECMWF SLIGHTLY SPEEDIER WITH THE ASSOCIATED SURFACE LOW (REACHES SOUTHERN LAKE MICHIGAN) THAN THE GFS (NORTHERN MISSISSIPPI RIVER VALLEY) BY 00Z TUES. A LOOK AT THE GFS/GEM ENSEMBLES SUGGESTS A COMPROMISE IS IN ORDER (NORTHERN ILL) AND THEREFORE WE SHOULD SEE INCREASING MID-UPPER LEVEL CLOUDS THROUGH THE DAY...BUT ENOUGH DRY AIR WILL BE IN PLACE TO PREVENT SNOW TO REACH THE SURFACE OUTSIDE OF THE LAKE EFFECT AREAS. HIGH TEMPERATURES WILL BE COLD ONCE AGAIN...WITH HIGHS IN THE LOWER TO MIDDLE TEENS. TUESDAY THROUGH FRIDAY...MODELS CONTINUE TO REMAIN IN VERY GOOD AGREEMENT WITH THE UPCOMING PATTERN FOR NEXT WEEK...AND ITS A PATTERN THAT LOOKS BITTERLY COLD FOR THE EASTERN HALF OF NORTH AMERICA BY THE END OF THIS PERIOD. STRONG WESTERN NOAM RIDGE STRENGTHENS AS IT RETROGRADES SLIGHTLY FROM THE YUKON TO EASTERN ALASKA PRODUCING 500MB HEIGHT ANOMALIES 360 METERS ABOVE NORMAL BY 00Z TUESDAY. THIS WILL HELP TO CREATE UPPER LEVEL FLOW ORIGINATING DIRECTLY OUT OF THE ARCTIC AND PRODUCE 500MB HEIGHT ANOMALIES IN EXCESS OF 280 METERS BELOW NORMAL BY 00Z FRI DOWNSTREAM OVER THE WESTERN GREAT LAKES. GFS ENSEMBLE MEMBERS ARE IN REMARKABLE AGREEMENT WITH THE STRENGTH OF THE RIDGE AS SHOWN BY THE LOW STANDARD DEVIATIONS WITHIN THE RIDGE AXIS WITH THE LARGEST SPREAD ON THE PERIPHERY WHICH INDICATES UNCERTAINTY IN THE LOCATION OF THE RIDGE. OVER THE LAST TWO DAYS...GFS ENSEMBLES HAVE BEEN TRENDING WEST WITH THE CORE OF THE COLD AIR...NOW PLACING IT OVER THE NORTHERN PLAINS WITH ONSET COMING NEXT THURSDAY. MAIN FORECAST CONCERNS INCLUDE TIMING OF THESE CLIPPERS AS THEY SLIDE DOWN THE EASTERN SIDE OF THE RIDGE...WITH EACH BRINGING A SLIGHT WARM UP AHEAD OF THEM...AND BITTERLY COLD AIR BEHIND THEM. ONE OF THESE WAVES IS EXPECTED TO APPROACH NORTHERN MICHIGAN ON TUESDAY...WITH THE NEXT ONE ARRIVING ON THURSDAY. THE LATTER OF THESE WAVES COULD POTENTIALLY BRING THE COLDEST AIR WE HAVE SEEN THUS FAR THIS WINTER FOR NEXT WEEKEND. OUTSIDE OF THESE WAVES...LAKE EFFECT SNOW POTENTIAL WILL KEEP A CHANCE OF SNOW SHOWERS POSSIBLE EACH DAY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY...THRU 8 AM...MIZ008-015>024-026>030-033>036. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 639 PM EST FRI JAN 26 2007 .UPDATE...OBS/RADAR TRENDS/CALLS TO LAW ENFORCEMENT INDICATE DZ/FZDZ IS VERY LIGHT TO NONEXISTENT IN THE SW AND FAR SOUTHERN ZONES. LOW LEVEL MOISTURE IS SHALLOWER AS YOU HEAD SW...LARGELY BELOW 800MB THERE VS UP TO 750MB OR SO IN APN AND THE STRAITS. WILL TAKE A STAB AT LOWERING THE WINTER WX ADVISORY FOR LEELANAU/TVC/HTL/STANDISH. WILL OBVIOUSLY MAINTAIN FURTHER NORTH...WHERE WIDESPREAD AND SUBSTANTIAL FZDZ HAS REDEVELOPED. ZOLTOWSKI && .PREV DISCUSSION ISSUED 400 PM FRI JAN 26... MID AFTERNOON SATELLITE/SURFACE/RADAR/AND RUC ANALYSIS SHOW BASIC MID LEVEL CONFIGURATION OF THE LAST SEVERAL DAYS (AND FOR MANY MORE DAYS TO COME...SEE EXTENDED DISCUSSION BELOW) REMAINING IN PLACE WITH WESTERN NOAM LONG WAVE RIDGE AND SUBSEQUENT DOWNSTREAM CENTRAL AND EASTERN CONUS TROUGH. EASTERN CONUS TROUGH ABOUT TO BE REINFORCED AS VIGOROUS NORTHERN STREAM SHORTWAVE...AND ASSOCIATED HEIGHT FALLS...IS DIVING SOUTHEAST ACROSS CENTRAL MANITOBA. AT THE SURFACE...ELONGATED 999MB LOW PRESSURE EXTENDS FROM WESTERN ONTARIO TO NORTHERN WISCONSIN. SURFACE WARM FRONT EXTENDING EAST FROM THE LOW OVER NORTHERN MICHIGAN RACING OFF TO THE NORTHEAST AS LOW AND MID LEVEL WAA ADVECTION CONTINUES TO STRENGTHEN AHEAD OF SYSTEM. FARTHER WEST...FIRST IN A SERIES OF COLD FRONTS USHERING IN PROGRESSIVELY COLDER AIR EXTENDS FROM EASTERN PLAINS SOUTHWEST THROUGH THE CENTRAL PLAINS. REGIONAL RADAR PLOTS SHOW WHAT REMAINS OF THIS MORNINGS FRONTOGENETICALLY FORCED SNOWFALL SLIDING EAST OVER EASTERN LAKE HURON. WITH BEST DYNAMICS AND MID LEVEL MOISTURE PULLING OFF TO THE EAST...NORTHERN LOWER MICHIGAN SEEING WIDESPREAD AREAS OF LIGHT FREEZING DRIZZLE AND FINE SNOWFLAKES WITH BULK OF REMAINING MOISTURE REMAINING BELOW -10C...PER 12Z MODEL POINT SOUNDINGS. FORECAST CONCERNS TONIGHT CENTER ON FREEZING DRIZZLE POTENTIAL THIS EVENING WITH SNOWFALL POTENTIAL TAKING CENTER STAGE LATER TONIGHT. TONIGHT...12 MODEL SUITE IN EXCELLENT AGREEMENT SHOWING MANITOBA SHORTWAVE CONTINUE TO SLIDE SOUTHEAST...TO A POSITION AT THE NORTHEAST END OF LAKE SUPERIOR BY MORNING. ASSOCIATED SURFACE LOW TRACKS RIGHT ACROSS NORTHERN MICHIGAN OVERNIGHT...WITH TRAILING COLD FRONT CLEARING THE AREA TOWARDS MORNING. ALTHOUGH SURFACE SYSTEM SLIDES THROUGH THE HEART OF THE AREA...BEST MID AND UPPER LEVEL SUPPORT FOR SYNOPTIC PRECIPITATION REMAINS NORTH OF THE REGION...CLOSER TO THE SHORTWAVE. MODEL POINT SOUNDINGS FOR THE NORTHERN LOWER CONTINUE TO SUPPORT FREEZING DRIZZLE THROUGH THIS EVENING WITH LIMITED MID LEVEL MOISTURE...SATURATED CONDITIONS BELOW -10C...AND SOME WEAK SHEAR AT TOP OF INVERSION. FARTHER NORTH...EASTERN UPPER MORE MARGINAL ACCORDING TO SOUNDINGS AND WILL MENTION SNOW SHOWER/FREEZING DRIZZLE MIX WITH LESS ICE ACCUMULATION EXPECTED. ALSO SOME CONCERN ALONG THE SAINT MARYS RIVER OF SOME SOUTHEAST FLOW LAKE HURON ENHANCEMENT WITH EVENING DELTA T/S IN THE LOW TEENS. SOME EVIDENCE OF THIS ALREADY OCCURING WITH THE SOO REPORTING LIGHT SNOW FOR SEVERAL HOURS DESPITE DYNAMICAL FORCING NOW WELL OFF TO THEIR NORTHEAST. LAST FEW SCANS OF MONTREAL RIVER CANADA RADAR SHOWS EXPANDING AREA OF LIGHT SNOW AT THE NORTHWEST END OF THE NORTH CHANNEL...WHICH ALSO MIGHT BE A SIGN OF SOME LAKE ENHANCEMENT KICKING IN. HAVE LEFT LIKELY POPS THIS EVENING TO ACCOUNT FOR THIS WITH ACCUMULATIONS UP TO AN INCH RIGHT ALONG THE RIVER SYSTEM. AFTER MIDNIGHT...WEST TO WEST NORTHWEST FLOW CAA KICKS IN WITH 850MB TEMPERATURES DROPPING TO -11C TO -12C OVER NORTHERN LAKE MICHIGAN AND EASTERN LAKE SUPERIOR. MID LEVEL COOLING COMBINED WITH SOME SCOURING OUT OF LOW LEVEL MOISTURE SHOULD PUT AN END TO THE FREEZING DRIZZLE THREAT. FOCUS THEN SHIFTS TO LAKE EFFECT/ENHANCED SNOW POTENTIAL AS DELTA T/S DROP TO RIGHT AROUND 13C. BUFKIT AND POINT SOUNDING ANALYSIS SHOWS INVERSION LEVELS OF ONLY ABOUT 3.5KFT AND 850MB-700MB MOISTURE <50 PERCENT OVER NORTHERN LAKE MICHIGAN AND >70 PERCENT OVER EASTERN LAKE SUPERIOR. DID TRIM POPS SOME IN FAVORED WEST NORTHWEST FLOW AREAS OF THE NORTHERN LOWER. KEPT POPS IN HIGH CHANCE CATEGORY NEAR WHITEFISH POINT WITH LONGER FETCH LENGTH AND BETTER MID LEVEL MOISTURE. MARINE...COMPLICATED MARINE FORECAST OVERNIGHT AS WINDS VEER AROUND NORTHWESTERLY. WILL LEAVE CURRENT SCA FOR SELECTED NEARSHORE WATERS OF LAKE HURON AND MICHIGAN THROUGH THIS EVENING TO ACCOUNT PRIMARILY FOR GUST SOUTH TO SOUTHEAST WINDS. AFTER A LULL LATER THIS EVENING...WINDS WEST NORTHWEST WINDS PICK UP OVER NORTHERN LAKE MICHIGAN. HAVE GONE AHEAD AND ADDED NORWOOD MICHIGAN TO THE BRIDGE NEARSHORE ZONE TO THE LAKE MICHIGAN GROUP TO ACCOUNT PRIMARILY FOR WAVES. WILL LET LAKE HURON NEARSHORE WATERS EXPIRE AS WIND FIELDS TAKE LONGER TO ORGANIZE. MSB LATER PERIODS...ACTIVE PERIOD SHAPING UP AS A SERIES OF CLIPPERS WILL TRAVERSE ACROSS THE NORTHERN GREAT LAKES. FIRST OF THESE SYSTEMS WILL ARRIVE ON SATURDAY AFTERNOON WITH A SECOND CLOSE BEHIND IT MOVING IN ON SUNDAY. THIS WILL SET THE STAGE FOR A PERIOD OF ACCUMULATING LAKE EFFECT SNOWS FOR EASTERN UPPER AND NORTHWEST LOWER MICHIGAN. THIS LATTER SYSTEM WILL ALSO BRING A SURGE OF BELOW NORMAL TEMPERATURES...WHICH LOOKS ONLY TO BE A PRECURSOR OF WHAT IS TO COME LATER NEXT WEEK. OTHER CLIPPERS TAKE AIM ON THE GREAT LAKES ON TUESDAY AND THURSDAY. THE LAST IN THE SERIES OF WAVES COULD POTENTIALLY BRING SOME OF THE COLDEST AIR IN YEARS TO THE GREAT LAKES FOR NEXT WEEKEND AS AIR ORIGINATING DIRECTLY OUT OF THE NORTH POLE DIVES SOUTH. MODELS IN GENERAL HAVE A PRETTY GOOD HANDLE ON THE OVERALL FLOW PATTERN OVER THE NEXT 7 DAYS. HAVE MOSTLY USED A BLEND OF THE GFS AND ECMWF...AND HAVE MIXED IN A LITTLE OF THE NAM THROUGH ABOUT 48 TO 60 HOURS OUT. TOMORROW...STRONG SHORTWAVE AS SEEN ON WV IMAGERY OVER MANITOBA WILL PASS ACROSS THE CWA WITH THE BEST FORCING ARRIVING ACROSS LOWER MICHIGAN DURING THE AFTERNOON. AS THE SHORTWAVE APPROACHES...850-700MB RH VALUES BECOME NEARLY SATURATED AND INVERSION HEIGHTS INCREASE FROM 4KFT AT 12Z TO 7KFT BY 00Z SUN. 850MB TEMPERATURES START OUT MARGINAL FOR LAKE EFFECT BETWEEN -10C AND -12C CREATING DELTA T`S AROUND 13C TO 15C...BUT COLD ADVECTION OVER THE COURSE OF THE MORNING WILL CREATE A MORE FAVORABLE THERMODYNAMIC PROFILE FOR LAKE EFFECT (DELTA T`S INCREASE BY A COUPLE DEGREES BY 18Z AND A COUPLE DEGREES MORE BY 00Z). SECONDARY COLD FRONT APPROACHES THE SOUTH SHORE OF LAKE SUPERIOR BY 00Z...WHOSE ADDED CONVERGENCE WILL HELP BOOST ONGOING LAKE EFFECT SNOW. BECAUSE OF THE INCREASINGLY FAVORABLE CONDITIONS FOR SNOW DURING THE AFTERNOON...WILL KEEP CHANCEY TO LIKELY ACROSS LAKE EFFECT PRONE AREAS DURING THE MORNING HOURS...AND CATEGORICAL OVER THESE SAME AREAS FOR THE AFTERNOON. SNOW AMOUNTS WILL PROBABLY IN THE 1-3 INCH RANGE FOR THE LAKE EFFECT AREAS NEAR WHITEFISH POINT AND THE TYPICAL CORRIDOR ACROSS NORTHWEST LOWER. SATURDAY NIGHT INTO SUNDAY... LEADING SHORTWAVE WILL MOVE SOUTHEAST AND CLEAR THE CWA DURING THE EVENING HOURS. HOWEVER...SECONDARY SHORTWAVE WILL MAINTAIN THE CYCLONIC FLOW OVER THIS PERIOD AND DRIVE AN ARCTIC FRONT SOUTH OVERNIGHT. GFS HAS BEEN TRENDING SLOWER WITH THE FRONTAL PASSAGE...MORE IN LINE WITH THE NAM OVER THE PAST COUPLE DAYS. STRONG COLD ADVECTION ENSUES BEHIND THIS FRONT AS WNW WINDS SHIFT TO THE NNW OR DUE NORTH DIRECTION AND WILL USHER IN 850MB TEMPS BELOW -20C. IN ADDITION...MODEL 850-700MB RH FIELDS KEEP PLENTY OF MOISTURE WITHIN THIS CYCLONIC FLOW...WHILE INVERSION HEIGHTS REMAIN HIGH ACROSS NORTHWEST LOWER (ABOVE 6KFT) BUT DECREASE ACROSS EASTERN UPPER ON SUNDAY SINCE UPPER LEVEL TROUGHING WILL BE EXITING HERE FIRST. THIS APPEARS TO BE A PRETTY GOOD SETUP FROM A LAKE EFFECT STANDPOINT WITH SHARP LOW LEVEL CYCLONIC FLOW ACROSS THE REGION TO ENHANCE CONVERGENCE. WITH THE LOW LEVEL FLOW OUT OF THE NORTHEAST FOR A GOOD PORTION OF THE NIGHT ACROSS EASTERN UPPER...AND ONSHORE NW TO N FLOW ACROSS NORTHWEST LOWER (WITH THE STRONGEST FORCING)...EXPECT THE HIGHEST ACCUMULATIONS TO OCCUR ACROSS NORTHWEST LOWER AND WILL REFLECT THIS IN THE GRIDS. HAVE THOUGHT ABOUT A PUTTING UP A LAKE EFFECT SNOW WATCH...BUT UNCERTAINTY WITH THE FRONTAL PASSAGE TIMING AND THE CORRESPONDING VEERING OF WINDS HAS MADE IT QUITE DIFFICULT TO PINPOINT AN AREA WHICH CAN CONFIDENTLY SAY WILL GET THE MOST SNOW. WILL ALSO HAVE TO WATCH FOR ACCUMULATING SNOW ACROSS NE LOWER OVERNIGHT INTO SUNDAY MORNING WITH THE SHARP NE FLOW IN PLACE. SUNDAY NIGHT INTO MONDAY...UPPER LEVEL TROUGH REMAINS IN PLACE OVERNIGHT WITH DRIER AIR MOVING IN AS THE NIGHT WEARS ON. WITH THE UPPER TROUGH EXITING...1000-850MB WINDS BACK FROM THE NNW TO WNW WITH 850MB TEMPERATURES (-20C) HARDLY WARMING WHATSOEVER...AND INVERSION HEIGHTS WILL FALL THROUGH THE DAY. THEREFORE...BELIEVE THE ONGOING LAKE EFFECT SNOW SHOWERS WILL DIMINISH THROUGH THE PERIOD SO WILL KEEP HIGHER POPS (LIKELY) GOING FOR SUNDAY NIGHT AND LOWER POPS (CHANCE) FOR WNW FLOW AREAS ON MONDAY. NEXT CLIPPER SYSTEM DIVES SE OVER THE NORTHERN PLAINS ON MONDAY. TIMING OF THIS SYSTEM STILL A LITTLE SUSPECT WITH THE ECMWF SLIGHTLY SPEEDIER WITH THE ASSOCIATED SURFACE LOW (REACHES SOUTHERN LAKE MICHIGAN) THAN THE GFS (NORTHERN MISSISSIPPI RIVER VALLEY) BY 00Z TUES. A LOOK AT THE GFS/GEM ENSEMBLES SUGGESTS A COMPROMISE IS IN ORDER (NORTHERN ILL) AND THEREFORE WE SHOULD SEE INCREASING MID-UPPER LEVEL CLOUDS THROUGH THE DAY...BUT ENOUGH DRY AIR WILL BE IN PLACE TO PREVENT SNOW TO REACH THE SURFACE OUTSIDE OF THE LAKE EFFECT AREAS. HIGH TEMPERATURES WILL BE COLD ONCE AGAIN...WITH HIGHS IN THE LOWER TO MIDDLE TEENS. TUESDAY THROUGH FRIDAY...MODELS CONTINUE TO REMAIN IN VERY GOOD AGREEMENT WITH THE UPCOMING PATTERN FOR NEXT WEEK...AND ITS A PATTERN THAT LOOKS BITTERLY COLD FOR THE EASTERN HALF OF NORTH AMERICA BY THE END OF THIS PERIOD. STRONG WESTERN NOAM RIDGE STRENGTHENS AS IT RETROGRADES SLIGHTLY FROM THE YUKON TO EASTERN ALASKA PRODUCING 500MB HEIGHT ANOMALIES 360 METERS ABOVE NORMAL BY 00Z TUESDAY. THIS WILL HELP TO CREATE UPPER LEVEL FLOW ORIGINATING DIRECTLY OUT OF THE ARCTIC AND PRODUCE 500MB HEIGHT ANOMALIES IN EXCESS OF 280 METERS BELOW NORMAL BY 00Z FRI DOWNSTREAM OVER THE WESTERN GREAT LAKES. GFS ENSEMBLE MEMBERS ARE IN REMARKABLE AGREEMENT WITH THE STRENGTH OF THE RIDGE AS SHOWN BY THE LOW STANDARD DEVIATIONS WITHIN THE RIDGE AXIS WITH THE LARGEST SPREAD ON THE PERIPHERY WHICH INDICATES UNCERTAINTY IN THE LOCATION OF THE RIDGE. OVER THE LAST TWO DAYS...GFS ENSEMBLES HAVE BEEN TRENDING WEST WITH THE CORE OF THE COLD AIR...NOW PLACING IT OVER THE NORTHERN PLAINS WITH ONSET COMING NEXT THURSDAY. MAIN FORECAST CONCERNS INCLUDE TIMING OF THESE CLIPPERS AS THEY SLIDE DOWN THE EASTERN SIDE OF THE RIDGE...WITH EACH BRINGING A SLIGHT WARM UP AHEAD OF THEM...AND BITTERLY COLD AIR BEHIND THEM. ONE OF THESE WAVES IS EXPECTED TO APPROACH NORTHERN MICHIGAN ON TUESDAY...WITH THE NEXT ONE ARRIVING ON THURSDAY. THE LATTER OF THESE WAVES COULD POTENTIALLY BRING THE COLDEST AIR WE HAVE SEEN THUS FAR THIS WINTER FOR NEXT WEEKEND. OUTSIDE OF THESE WAVES...LAKE EFFECT SNOW POTENTIAL WILL KEEP A CHANCE OF SNOW SHOWERS POSSIBLE EACH DAY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY...THIS EVENING...MIZ016>019-021>024-027>030-035-036. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 403 PM EST FRI JAN 26 2007 .SYNOPSIS... WATER VAPOR LOOP SHOWS AN UPSTREAM SHORTWAVE OVER WRN ONTARIO/NRN MN WITH A SECONDARY SHORTWAVE PINWHEELING THROUGH CENTRAL MANITOBA/SASKATCHEWAN. DOWNSTREAM FROM SHORTWAVES...MID-LVL RDGG OVER THE UPPER GREAT LAKES HAS RESULTED IN MOSTLY DRY CONDITIONS ACROSS MUCH OF THE FCST AREA...EXCEPT FOR SOME UPSLOPE FLURRIES/PATCHY -FZDZ OVER PORTIONS OF CENTRAL AND ERN COUNTIES. BASED ON LATEST RADAR LOOP AND SFC OBS LOOKS LIKE ANY LINGERING LAKE EFFECT SNOW OVER SCHOOLCRAFT COUNTY IS WANING DESPITE DECENT LOW-LEVEL CONVERGENCE ALONG SFC TROF THERE. SO WILL CANCEL SNOW ADVISORY FOR SRN SCHOOLCRAFT COUNTY. .SHORT TERM (TONIGHT)... SHORTWAVE OVER WRN ONTARIO IS EXPECTED TO DIVE ACROSS LAKE SUPERIOR TONIGHT AS BEST FORCING FROM THIS FEATURE WILL BE NE OF CWFA. SHORTWAVE WILL DRIVE SFC TROF NOW OVER FAR WRN UPR MI ACROSS THE REST OF THE FORECAST AREA LATER THIS EVENING INTO THE EARLY OVERNIGHT. WIND SHIFTING TO A MORE WNW DIRECTION BEHIND THE TROF SHOULD BRING SOME LES FLURRIES INTO WRN AND PERHAPS INTO CENTRAL COUNTIES AS WELL...BUT AGAIN DO NOT EXPECT ANYTHING MORE THAN FLURRIES GIVEN MARGINALLY COLD 850 MB TEMPS (-9/-10C) AND FAIRLY STRONG SUBSIDENCE INTO THIS EVENING. KEPT IN A MENTION OF LIGHT SNOW OR PATCHY -FZDZ OVER THE KEWEENAW AND ERN HALF COUNTIES WHERE UPSLOPE S-SE FLOW WILL BE PRESENT ALONG SFC TROF AND WEAK FORCING IS POSSIBLE AHEAD OF INCOMING SHORTWAVE. AFTER MIDNIGHT...SECONDARY SHORTWAVE APPROACHES WITH BETTER SHOT OF CAA AS 850 MB TEMPS BEGIN TO LOWER TO -14/-16C OVER THE WRN FCST AREA. INCREASINGLY CYCLONIC/CONVERGENT NW FLOW AND MORE FAVORABLE SNOW GROWTH WILL FAVOR NRN GOGEBIC COUNTY THROUGH SRN HOUGHTON COUNTIES FOR BURSTS OF MORE INTENSE SNOW TOWARD MORNING WITH ACCUMULATIONS OF 1 TO 2 INCHES. .LONG TERM (SATURDAY THROUGH FRIDAY)... THE MAIN FORECAST CONCERN WAS THIS WEEKEND AND THE INHERITED LAKE EFFECT SNOW WATCHES...AS SOME DECISIONS NEEDED TO BE MADE ON UPGRADES OR DOWNGRADES. LAKE EFFECT SNOW ADVISORIES WERE ALSO NEEDING TO BE POSTED FOR PORTIONS OF THE CWA. AS ON THE FENCE WITH A FEW OF WSW ISSUES THIS FORECAST ISSUANCE. THE FIRST HAS TO DO WITH PORTIONS OF NORTHWESTERN HOUGHTON COUNTY...WHERE WARNING CRITERIA IS EXPECTED TO BE CLOSE. THE SECOND WAS WITH DELTA COUNTY...WHICH WOULD ALSO BE CLOSE TO THE 12 HOUR ADVISORY CRITERIA OF 3 TO 6 INCHES...PARTICULARLY ACROSS THE EXTREME NORTHERN SLIVER OF THE COUNTY. DECIDED TO GO WITH THE ADVISORY THERE. THE THIRD THING WOULD BE WITH RESPECT TO NORTHERN KEWEENAW COUNTY...AS WINDS INCREASE OUT OF THE NORTH LATE SATURDAY AFTERNOON INTO EARLY SUNDAY MORNING...AND GET CLOSE TO BLOWING SNOW ADVISORY CRITERIA. FOR THIS...HAVE ADDED THE MENTION OF LOCALIZED BLOWING SNOW TO THE WSW. THE SFC LOW (DOUBLE BARREL LOW CONFIGURATION) CURRENTLY STRETCHING FROM SOUTHWEST ONTARIO TO NORTHERN WISCONSIN WILL CONTINUE TO SLOWLY SLIDE SOUTHEASTWARD OVER LAKE SUPERIOR OVERNIGHT TONIGHT...AND THEN STRETCH FROM SOUTHEASTERN LAKE SUPERIOR TO SOUTHERN LAKE HURON BY 12Z SATURDAY. THIS WILL BEGIN TO TURN OUR WINDS TO A MORE FAVORABLE N-NW DIRECTION QUICKEST WEST 09Z AND 18Z CENTRAL...AND 850 TEMPS OF -4C AT 12Z THIS MORNING OFF OF THE INL SOUNDING WILL BE ALLOWED TO FALL A BETTER LAKE EFFECT TEMPERATURE OF -10C BY 06Z SATURDAY ACROSS THE LAKE SUPERIOR SHORELINE...COOLING OFF TO -12 TO -15C BY 12Z SATURDAY...WITH STILL LITTLE IN THE WAY OF AN INVERSION TO SPEAK OF. FOR QPF AMOUNTS...MADE FEW ADJUSTMENTS...STILL LINING UP CLOSER TO THE RUC13 AND REGIONAL CAN. FOR SATURDAY...TEMPS LOOK GOOD FOR SATURDAY AFTERNOON...WITH GUIDANCE CLUSTERED AROUND OUR INHERITED VALUES...SEE NO NEED TO MAKE ANY DRASTIC CHANGES. FOR MONDAY AND MONDAY NIGHT...TEMPERATURES DURING THE DAY MONDAY BECOME TRICKY. PLENTY OF COLD AIR WILL BE OVERHEAD...MODERATING BY A COUPLE OF DEGREES C AT 850MB WHEN COMPARED TO SUNDAY. HIGH CLOUDS WILL ALSO BE SLIDING IN DURING THE DAYTIME HOURS IN OUR NORTHWESTERLY FLOW OUT AHEAD OF OUR NEXT SYSTEM. ENDED UP HEDGING THE TEMPS SLIGHTLY TOWARDS THE GFS...WHICH IS ONE OF THE WARMER MODELS GUIDANCE WISE AT THAT TIME. IN TERMS OF WEATHER AND POPS MONDAY NIGHT INTO TUESDAY...START OUT THE NIGHT WITH NNE WINDS WHICH WOULD FAVOR JUST KEEPING POPS ACROSS THE EASTERN THIRD NEAR LAKE SUPERIOR...WITH A DRYING TREND ELSEWHERE. SHORTWAVE TROUGH SHOULD BE OVER NORTHERN AND CENTRAL NORTH DAKOTA MONDAY MORNING...AND THEN PUSH WELL TO OUR SOUTH AND OVER SOUTHWESTERN WISCONSIN BY 06Z TUESDAY. MUCH OF THE ENERGY ASSOCIATED WITH IT REMAINING TO OUR SOUTH AS WELL...LEAVING THE UPPER PENINSULA TEMPORARILY BETWEEN SYSTEMS. HAVE OPTED TO LOWER POPS ACROSS MUCH OF THE REGION...BUT STILL KEEPING 30-40 POPS FOR THE MORE FAVORED EASTERN THIRD. TAKING A LOOK AT THE GFS ENSEMBLES...THE OPERATIONAL GFS MAY BE ONE OF THE FURTHEST SOUTH OPTIONS FOR THE TROUGH...LEAVING SOME UNCERTAINTY IN PLAY FOR MONDAY NIGHT INTO TUESDAY. EVEN WITH THIS SAID IT SEEMS TO BE BACKED BY SOME OF THE OTHER GLOBAL MODELS INCLUDING THE ECMWF. AS FOR THE EXTENDED (TUESDAY THROUGH FRIDAY... ACTUALLY WARMED UP TEMPERATURES SLIGHTLY FOR DAYS 6 AND NEW 7 (THURSDAY AND FRIDAY)...UTILIZING LATEST HPC GUIDANCE FOR THAT PERIOD. IN FACT WENT ABOUT 5 DEGREES WARMER...PARTICULARLY ACROSS THE EASTERN HALF OF THE CWA FOR WEDNESDAY NIGHT AND THURSDAY AFTERNOON. OTHERWISE THROUGH THIS PERIOD...FEW CHANGES WERE MADE TO THE INHERITED FORECAST...AS EXTENDED GUIDANCE FOR OUR REGION CONTINUES TO BE FAIRLY WELL IN LINE FOR MUCH OF THIS TIME PERIOD. HPC UTILIZED THE 00Z ECMWF FOR THE START OF THE FORECAST PERIOD...AND TRANSITIONED TO THE 00Z NCEP ENSEMBLE MEAN. ZONAL FLOW WEDNESDAY...BUT WITH LINGERING MOISTURE HAVE NOT YET BEEN ABLE TO TAKE POPS OUT OF THE FORECAST. NEXT 500MB TROUGH DIGS IN WEDNESDAY NIGHT INTO THURSDAY. HAVE INCREASED THE POSSIBILITY OF SYNOPTIC SNOW FOR THURSDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FROM 1 PM SATURDAY TO 1 AM EST MONDAY FOR MIZ004>006. LAKE EFFECT SNOW WARNING FROM 7 AM EST /6 AM CST/ SATURDAY TO 7 PM EST /6 PM CST/ SUNDAY FOR MIZ002-009. LAKE EFFECT SNOW ADVISORY FROM 10 AM SATURDAY TO 10 PM EST SUNDAY FOR MIZ001-003. LAKE EFFECT SNOW ADVISORY FROM 1 PM SATURDAY TO 1 AM EST MONDAY FOR MIZ013-085. && $$ .SHORT TERM...KF .LONG TERM...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 400 PM EST FRI JAN 26 2007 .DISCUSSION...MID AFTERNOON SATELLITE/SURFACE/RADAR/AND RUC ANALYSIS SHOW BASIC MID LEVEL CONFIGURATION OF THE LAST SEVERAL DAYS (AND FOR MANY MORE DAYS TO COME...SEE EXTENDED DISCUSSION BELOW) REMAINING IN PLACE WITH WESTERN NOAM LONG WAVE RIDGE AND SUBSEQUENT DOWNSTREAM CENTRAL AND EASTERN CONUS TROUGH. EASTERN CONUS TROUGH ABOUT TO BE REINFORCED AS VIGOROUS NORTHERN STREAM SHORTWAVE...AND ASSOCIATED HEIGHT FALLS...IS DIVING SOUTHEAST ACROSS CENTRAL MANITOBA. AT THE SURFACE...ELONGATED 999MB LOW PRESSURE EXTENDS FROM WESTERN ONTARIO TO NORTHERN WISCONSIN. SURFACE WARM FRONT EXTENDING EAST FROM THE LOW OVER NORTHERN MICHIGAN RACING OFF TO THE NORTHEAST AS LOW AND MID LEVEL WAA ADVECTION CONTINUES TO STRENGTHEN AHEAD OF SYSTEM. FARTHER WEST...FIRST IN A SERIES OF COLD FRONTS USHERING IN PROGRESSIVELY COLDER AIR EXTENDS FROM EASTERN PLAINS SOUTHWEST THROUGH THE CENTRAL PLAINS. REGIONAL RADAR PLOTS SHOW WHAT REMAINS OF THIS MORNINGS FRONTOGENETICALLY FORCED SNOWFALL SLIDING EAST OVER EASTERN LAKE HURON. WITH BEST DYNAMICS AND MID LEVEL MOISTURE PULLING OFF TO THE EAST...NORTHERN LOWER MICHIGAN SEEING WIDESPREAD AREAS OF LIGHT FREEZING DRIZZLE AND FINE SNOWFLAKES WITH BULK OF REMAINING MOISTURE REMAINING BELOW -10C...PER 12Z MODEL POINT SOUNDINGS. FORECAST CONCERNS TONIGHT CENTER ON FREEZING DRIZZLE POTENTIAL THIS EVENING WITH SNOWFALL POTENTIAL TAKING CENTER STAGE LATER TONIGHT. TONIGHT...12 MODEL SUITE IN EXCELLENT AGREEMENT SHOWING MANITOBA SHORTWAVE CONTINUE TO SLIDE SOUTHEAST...TO A POSITION AT THE NORTHEAST END OF LAKE SUPERIOR BY MORNING. ASSOCIATED SURFACE LOW TRACKS RIGHT ACROSS NORTHERN MICHIGAN OVERNIGHT...WITH TRAILING COLD FRONT CLEARING THE AREA TOWARDS MORNING. ALTHOUGH SURFACE SYSTEM SLIDES THROUGH THE HEART OF THE AREA...BEST MID AND UPPER LEVEL SUPPORT FOR SYNOPTIC PRECIPITATION REMAINS NORTH OF THE REGION...CLOSER TO THE SHORTWAVE. MODEL POINT SOUNDINGS FOR THE NORTHERN LOWER CONTINUE TO SUPPORT FREEZING DRIZZLE THROUGH THIS EVENING WITH LIMITED MID LEVEL MOISTURE...SATURATED CONDITIONS BELOW -10C...AND SOME WEAK SHEAR AT TOP OF INVERSION. FARTHER NORTH...EASTERN UPPER MORE MARGINAL ACCORDING TO SOUNDINGS AND WILL MENTION SNOW SHOWER/FREEZING DRIZZLE MIX WITH LESS ICE ACCUMULATION EXPECTED. ALSO SOME CONCERN ALONG THE SAINT MARYS RIVER OF SOME SOUTHEAST FLOW LAKE HURON ENHANCEMENT WITH EVENING DELTA T/S IN THE LOW TEENS. SOME EVIDENCE OF THIS ALREADY OCCURING WITH THE SOO REPORTING LIGHT SNOW FOR SEVERAL HOURS DESPITE DYNAMICAL FORCING NOW WELL OFF TO THEIR NORTHEAST. LAST FEW SCANS OF MONTREAL RIVER CANADA RADAR SHOWS EXPANDING AREA OF LIGHT SNOW AT THE NORTHWEST END OF THE NORTH CHANNEL...WHICH ALSO MIGHT BE A SIGN OF SOME LAKE ENHANCEMENT KICKING IN. HAVE LEFT LIKELY POPS THIS EVENING TO ACCOUNT FOR THIS WITH ACCUMULATIONS UP TO AN INCH RIGHT ALONG THE RIVER SYSTEM. AFTER MIDNIGHT...WEST TO WEST NORTHWEST FLOW CAA KICKS IN WITH 850MB TEMPERATURES DROPPING TO -11C TO -12C OVER NORTHERN LAKE MICHIGAN AND EASTERN LAKE SUPERIOR. MID LEVEL COOLING COMBINED WITH SOME SCOURING OUT OF LOW LEVEL MOISTURE SHOULD PUT AN END TO THE FREEZING DRIZZLE THREAT. FOCUS THEN SHIFTS TO LAKE EFFECT/ENHANCED SNOW POTENTIAL AS DELTA T/S DROP TO RIGHT AROUND 13C. BUFKIT AND POINT SOUNDING ANALYSIS SHOWS INVERSION LEVELS OF ONLY ABOUT 3.5KFT AND 850MB-700MB MOISTURE <50 PERCENT OVER NORTHERN LAKE MICHIGAN AND >70 PERCENT OVER EASTERN LAKE SUPERIOR. DID TRIM POPS SOME IN FAVORED WEST NORTHWEST FLOW AREAS OF THE NORTHERN LOWER. KEPT POPS IN HIGH CHANCE CATEGORY NEAR WHITEFISH POINT WITH LONGER FETCH LENGTH AND BETTER MID LEVEL MOISTURE. MARINE...COMPLICATED MARINE FORECAST OVERNIGHT AS WINDS VEER AROUND NORTHWESTERLY. WILL LEAVE CURRENT SCA FOR SELECTED NEARSHORE WATERS OF LAKE HURON AND MICHIGAN THROUGH THIS EVENING TO ACCOUNT PRIMARILY FOR GUST SOUTH TO SOUTHEAST WINDS. AFTER A LULL LATER THIS EVENING...WINDS WEST NORTHWEST WINDS PICK UP OVER NORTHERN LAKE MICHIGAN. HAVE GONE AHEAD AND ADDED NORWOOD MICHIGAN TO THE BRIDGE NEARSHORE ZONE TO THE LAKE MICHIGAN GROUP TO ACCOUNT PRIMARILY FOR WAVES. WILL LET LAKE HURON NEARSHORE WATERS EXPIRE AS WIND FIELDS TAKE LONGER TO ORGANIZE. MSB LATER PERIODS...ACTIVE PERIOD SHAPING UP AS A SERIES OF CLIPPERS WILL TRAVERSE ACROSS THE NORTHERN GREAT LAKES. FIRST OF THESE SYSTEMS WILL ARRIVE ON SATURDAY AFTERNOON WITH A SECOND CLOSE BEHIND IT MOVING IN ON SUNDAY. THIS WILL SET THE STAGE FOR A PERIOD OF ACCUMULATING LAKE EFFECT SNOWS FOR EASTERN UPPER AND NORTHWEST LOWER MICHIGAN. THIS LATTER SYSTEM WILL ALSO BRING A SURGE OF BELOW NORMAL TEMPERATURES...WHICH LOOKS ONLY TO BE A PRECURSOR OF WHAT IS TO COME LATER NEXT WEEK. OTHER CLIPPERS TAKE AIM ON THE GREAT LAKES ON TUESDAY AND THURSDAY. THE LAST IN THE SERIES OF WAVES COULD POTENTIALLY BRING SOME OF THE COLDEST AIR IN YEARS TO THE GREAT LAKES FOR NEXT WEEKEND AS AIR ORIGINATING DIRECTLY OUT OF THE NORTH POLE DIVES SOUTH. MODELS IN GENERAL HAVE A PRETTY GOOD HANDLE ON THE OVERALL FLOW PATTERN OVER THE NEXT 7 DAYS. HAVE MOSTLY USED A BLEND OF THE GFS AND ECMWF...AND HAVE MIXED IN A LITTLE OF THE NAM THROUGH ABOUT 48 TO 60 HOURS OUT. TOMORROW...STRONG SHORTWAVE AS SEEN ON WV IMAGERY OVER MANITOBA WILL PASS ACROSS THE CWA WITH THE BEST FORCING ARRIVING ACROSS LOWER MICHIGAN DURING THE AFTERNOON. AS THE SHORTWAVE APPROACHES...850-700MB RH VALUES BECOME NEARLY SATURATED AND INVERSION HEIGHTS INCREASE FROM 4KFT AT 12Z TO 7KFT BY 00Z SUN. 850MB TEMPERATURES START OUT MARGINAL FOR LAKE EFFECT BETWEEN -10C AND -12C CREATING DELTA T`S AROUND 13C TO 15C...BUT COLD ADVECTION OVER THE COURSE OF THE MORNING WILL CREATE A MORE FAVORABLE THERMODYNAMIC PROFILE FOR LAKE EFFECT (DELTA T`S INCREASE BY A COUPLE DEGREES BY 18Z AND A COUPLE DEGREES MORE BY 00Z). SECONDARY COLD FRONT APPROACHES THE SOUTH SHORE OF LAKE SUPERIOR BY 00Z...WHOSE ADDED CONVERGENCE WILL HELP BOOST ONGOING LAKE EFFECT SNOW. BECAUSE OF THE INCREASINGLY FAVORABLE CONDITIONS FOR SNOW DURING THE AFTERNOON...WILL KEEP CHANCEY TO LIKELY ACROSS LAKE EFFECT PRONE AREAS DURING THE MORNING HOURS...AND CATEGORICAL OVER THESE SAME AREAS FOR THE AFTERNOON. SNOW AMOUNTS WILL PROBABLY IN THE 1-3 INCH RANGE FOR THE LAKE EFFECT AREAS NEAR WHITEFISH POINT AND THE TYPICAL CORRIDOR ACROSS NORTHWEST LOWER. SATURDAY NIGHT INTO SUNDAY... LEADING SHORTWAVE WILL MOVE SOUTHEAST AND CLEAR THE CWA DURING THE EVENING HOURS. HOWEVER...SECONDARY SHORTWAVE WILL MAINTAIN THE CYCLONIC FLOW OVER THIS PERIOD AND DRIVE AN ARCTIC FRONT SOUTH OVERNIGHT. GFS HAS BEEN TRENDING SLOWER WITH THE FRONTAL PASSAGE...MORE IN LINE WITH THE NAM OVER THE PAST COUPLE DAYS. STRONG COLD ADVECTION ENSUES BEHIND THIS FRONT AS WNW WINDS SHIFT TO THE NNW OR DUE NORTH DIRECTION AND WILL USHER IN 850MB TEMPS BELOW -20C. IN ADDITION...MODEL 850-700MB RH FIELDS KEEP PLENTY OF MOISTURE WITHIN THIS CYCLONIC FLOW...WHILE INVERSION HEIGHTS REMAIN HIGH ACROSS NORTHWEST LOWER (ABOVE 6KFT) BUT DECREASE ACROSS EASTERN UPPER ON SUNDAY SINCE UPPER LEVEL TROUGHING WILL BE EXITING HERE FIRST. THIS APPEARS TO BE A PRETTY GOOD SETUP FROM A LAKE EFFECT STANDPOINT WITH SHARP LOW LEVEL CYCLONIC FLOW ACROSS THE REGION TO ENHANCE CONVERGENCE. WITH THE LOW LEVEL FLOW OUT OF THE NORTHEAST FOR A GOOD PORTION OF THE NIGHT ACROSS EASTERN UPPER...AND ONSHORE NW TO N FLOW ACROSS NORTHWEST LOWER (WITH THE STRONGEST FORCING)...EXPECT THE HIGHEST ACCUMULATIONS TO OCCUR ACROSS NORTHWEST LOWER AND WILL REFLECT THIS IN THE GRIDS. HAVE THOUGHT ABOUT A PUTTING UP A LAKE EFFECT SNOW WATCH...BUT UNCERTAINTY WITH THE FRONTAL PASSAGE TIMING AND THE CORRESPONDING VEERING OF WINDS HAS MADE IT QUITE DIFFICULT TO PINPOINT AN AREA WHICH CAN CONFIDENTLY SAY WILL GET THE MOST SNOW. WILL ALSO HAVE TO WATCH FOR ACCUMULATING SNOW ACROSS NE LOWER OVERNIGHT INTO SUNDAY MORNING WITH THE SHARP NE FLOW IN PLACE. SUNDAY NIGHT INTO MONDAY...UPPER LEVEL TROUGH REMAINS IN PLACE OVERNIGHT WITH DRIER AIR MOVING IN AS THE NIGHT WEARS ON. WITH THE UPPER TROUGH EXITING...1000-850MB WINDS BACK FROM THE NNW TO WNW WITH 850MB TEMPERATURES (-20C) HARDLY WARMING WHATSOEVER...AND INVERSION HEIGHTS WILL FALL THROUGH THE DAY. THEREFORE...BELIEVE THE ONGOING LAKE EFFECT SNOW SHOWERS WILL DIMINISH THROUGH THE PERIOD SO WILL KEEP HIGHER POPS (LIKELY) GOING FOR SUNDAY NIGHT AND LOWER POPS (CHANCE) FOR WNW FLOW AREAS ON MONDAY. NEXT CLIPPER SYSTEM DIVES SE OVER THE NORTHERN PLAINS ON MONDAY. TIMING OF THIS SYSTEM STILL A LITTLE SUSPECT WITH THE ECMWF SLIGHTLY SPEEDIER WITH THE ASSOCIATED SURFACE LOW (REACHES SOUTHERN LAKE MICHIGAN) THAN THE GFS (NORTHERN MISSISSIPPI RIVER VALLEY) BY 00Z TUES. A LOOK AT THE GFS/GEM ENSEMBLES SUGGESTS A COMPROMISE IS IN ORDER (NORTHERN ILL) AND THEREFORE WE SHOULD SEE INCREASING MID-UPPER LEVEL CLOUDS THROUGH THE DAY...BUT ENOUGH DRY AIR WILL BE IN PLACE TO PREVENT SNOW TO REACH THE SURFACE OUTSIDE OF THE LAKE EFFECT AREAS. HIGH TEMPERATURES WILL BE COLD ONCE AGAIN...WITH HIGHS IN THE LOWER TO MIDDLE TEENS. TUESDAY THROUGH FRIDAY...MODELS CONTINUE TO REMAIN IN VERY GOOD AGREEMENT WITH THE UPCOMING PATTERN FOR NEXT WEEK...AND ITS A PATTERN THAT LOOKS BITTERLY COLD FOR THE EASTERN HALF OF NORTH AMERICA BY THE END OF THIS PERIOD. STRONG WESTERN NOAM RIDGE STRENGTHENS AS IT RETROGRADES SLIGHTLY FROM THE YUKON TO EASTERN ALASKA PRODUCING 500MB HEIGHT ANOMALIES 360 METERS ABOVE NORMAL BY 00Z TUESDAY. THIS WILL HELP TO CREATE UPPER LEVEL FLOW ORIGINATING DIRECTLY OUT OF THE ARCTIC AND PRODUCE 500MB HEIGHT ANOMALIES IN EXCESS OF 280 METERS BELOW NORMAL BY 00Z FRI DOWNSTREAM OVER THE WESTERN GREAT LAKES. GFS ENSEMBLE MEMBERS ARE IN REMARKABLE AGREEMENT WITH THE STRENGTH OF THE RIDGE AS SHOWN BY THE LOW STANDARD DEVIATIONS WITHIN THE RIDGE AXIS WITH THE LARGEST SPREAD ON THE PERIPHERY WHICH INDICATES UNCERTAINTY IN THE LOCATION OF THE RIDGE. OVER THE LAST TWO DAYS...GFS ENSEMBLES HAVE BEEN TRENDING WEST WITH THE CORE OF THE COLD AIR...NOW PLACING IT OVER THE NORTHERN PLAINS WITH ONSET COMING NEXT THURSDAY. MAIN FORECAST CONCERNS INCLUDE TIMING OF THESE CLIPPERS AS THEY SLIDE DOWN THE EASTERN SIDE OF THE RIDGE...WITH EACH BRINGING A SLIGHT WARM UP AHEAD OF THEM...AND BITTERLY COLD AIR BEHIND THEM. ONE OF THESE WAVES IS EXPECTED TO APPROACH NORTHERN MICHIGAN ON TUESDAY...WITH THE NEXT ONE ARRIVING ON THURSDAY. THE LATTER OF THESE WAVES COULD POTENTIALLY BRING THE COLDEST AIR WE HAVE SEEN THUS FAR THIS WINTER FOR NEXT WEEKEND. OUTSIDE OF THESE WAVES...LAKE EFFECT SNOW POTENTIAL WILL KEEP A CHANCE OF SNOW SHOWERS POSSIBLE EACH DAY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY... THIS EVENING...MIZ016-036>041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 103 PM EST FRI JAN 26 2007 .AVIATION... THE LARGE AREA OF SNOW THAT WAS AFFECTING THE REGION THIS MORNING CONTINUES TO PUSH OFF TO THE EAST AND WANE VERY QUICKLY...ALTHOUGH THERE IS ENOUGH LOW LEVEL MOISTURE THIS AFTERNOON TO SUPPORT A BRIEF PERIOD OF LIGHT FREEZING DRIZZLE. IN FAR SOUTHWESTERN LOWER MICHIGAN THERE IS CLEARING AND THAT IS PUSHING TOWARDS THE DETROIT AREA. THERE IS ENOUGH FORECAST UNCERTAINTY TO PRECLUDE THE CLEARING OF SKIES COMPLETELY FOR KDTW AND KDET. WINDS THIS AFTERNOON WILL START SOUTHEASTERLY AND VEER TOWARDS THE SOUTHWEST THIS EVENING AND OVERNIGHT. && .PREV DISCUSSION...ISSUED 1036 AM EST FRI JAN 26 2007 UPDATE... SNOW HAS INCREASED IN INTENSITY THIS MORNING WITH VISIBILITIES DOWN TO LESS THAN 1 MILE. NICE FGEN FORCING PER THE 12Z RUC ON THE 750MB SURFACE WHICH SLIDES NORTHEAST OF THE CWA BETWEEN 17Z-18Z. FURTHERMORE...ADDITIONAL LIFT FROM THE ENTRANCE REGION OF 130KT JET CENTERED OVER BUFFALO NY IS AIDING IN ADDITIONAL LIFT. IMPRESSIVE WARM ADVECTION AND MID LEVEL DRY SLOT IS STILL EXPECTED TO MOVE ACROSS THE REGION THIS AFTERNOON. BASED ON SOUNDINGS FROM THE RUC AND THE ARRIVAL OF THE NEW NAM...FREEZING DRIZZLE LOOKS GOOD AS WE LOSE MOISTURE AT THE DENDRITIC ICE GROWTH REGION. TEMPERATURES WILL CONTINUE TO CLIMB THROUGH THE 20S AND MIGHT CONTINUE TO RISE THROUGH THE NIGHT... PREV DISCUSSION...ISSUED AT 341 AM SHORT TERM...TODAY AND TONIGHT TRICKY FORECAST TODAY AS A BAND OF LIGHT SNOW SPREADS INTO THE AREA THIS MORNING IN WARM AIR ADVECTION REGIME. THIS SNOW WILL AMOUNT TO AN INCH OR TWO...WITH THE BEST ACCUMULATION POTENTIAL ALONG AND TO THE NORTHEAST OF I-75 OR SO. THERE WILL BE A SHARP CUTOFF IN LIGHT SNOW ACCUMULATION TO THE SOUTHWEST AS DRY AIR WORKS QUICKLY INTO THE AREA WITHIN INCREASING SOUTHWEST FLOW REGIME. THIS INTRUSION OF DRY AIR WILL FIRST STRIP AWAY MID AND UPPER LEVEL MOISTURE...LEADING TO PRECIPITATION CHANGING OVER FROM LIGHT SNOW TO FREEZING DRIZZLE AS SEMI-SATURATED PORTION OF THE ATMOSPHERE BECOMES LIMITED TO AREAS BELOW 800 MB...AND BELOW -10C...THUS LIMITING THE POTENTIAL FOR ICE NUCLEATION AND SNOWFLAKE PRODUCTION. WITHIN THIS PROCESS...THE DRY SLOT MAY EVEN ELIMINATE ENOUGH OF THE LOW LEVEL MOISTURE TO END OR AT LEAST LIMIT THE AMOUNT OF DRIZZLE OVER THE SOUTHERN CWA...ESPECIALLY BY AFTERNOON. WITH THIS MIXTURE OF PRECIPITATION...AND AFTER COORDINATION WITH SURROUNDING OFFICES...WILL BE GOING WITH A WINTER WEATHER ADVISORY TODAY FOR ALL BUT THE SOUTHERNMOST TWO COUNTIES IN THE CWA. THE SOUTHERN EDGE OF THIS ADVISORY WILL HAVE THE LIGHTEST PRECIPITATION BUT MOST FREEZING DRIZZLE POTENTIAL -VS- LIGHT SNOW...AND THE NORTHEAST THUMB REGION WILL HAVE BETTER SNOW ACCUMULATION...BUT LIMITED FREEZING DRIZZLE THROUGH THIS AFTERNOON. ALL IN ALL...THE PRECIPITATION WILL BE LIGHT...BUT WITH SURFACE TEMPERATURES IN THE SINGLE DIGITS TO TEENS AT THE START OF THE EVENT...THE DRIZZLE BY LATE MORNING/EARLY AFTERNOON WILL HAVE LITTLE PROBLEM FREEZING TO SURFACES. WILL LIMIT THE ADVISORY TO THE FIRST PERIOD AND ALLOW THE DAYSHIFT TO EVALUATE JUST HOW MUCH PRECIPITATION WILL CONTINUE INTO THIS EVENING. AT THIS TIME...IT APPEARS THE MOST WIDESPREAD FREEZING DRIZZLE AND/OR LIGHT SNOW BY THIS EVENING WILL BE LIMITED TO AREAS ALONG/NORTH OF I-69 OR PERHAPS THE M-59 CORRIDOR. THE ADVISORY MAY VERY WELL NEED TO BE EXTENDED INTO TONIGHT IN SOME AREAS. LONG TERM... NEXT SURGE OF ARCTIC AIR TO IMPACT SOUTHEAST MICHIGAN THIS WEEKEND...LIKELY LEADING TO ANOTHER ROUND OF ACCUMULATING SNOW...ESPECIALLY ACROSS THE THUMB REGION. TOO FAR OUT TO PIN DOWN THE DETAILS OF ANY LAKE HURON BANDS...AS TIMING AND STRENGTH OF UPPER WAVES AS SEEN ON DYNAMIC TROPOPAUSE VARY BETWEEN 00Z UKMET/NAM AND GFS. HOWEVER...WITH ALL MODELS SHOWING A WELL DEFINED SURFACE TROUGH LINGERING ACROSS SOUTHERN LOWER MICHIGAN AND 850 MB TEMPS FALLING TO AT LEAST -18 C...SNOW SHOWERS APPEAR TO BE A GOOD BET AND HAVE RAISED POPS TO 50 PERCENT SATURDAY NIGHT AND SUNDAY ACROSS MOST OF SOUTHEAST MICHIGAN...WITH LIKELY POPS ACROSS THE THUMB REGION BY SUNDAY. POPS FOR ONE OR BOTH OF THOSE PERIODS WILL PROBABLY HAVE TO BE BUMPED UP AS TIMING OF THE UPPER WAVES BECOME CLEARER. WATER VAPOR IMAGERY SHOW A LARGE UPPER LEVEL CIRCULATION OVER CENTRAL CANADA (ALBERTA/SASKATCHEWAN/MANITOBA) WITH MULTIPLE VORTS ROTATING ABOUT. 00Z UKMET/CANADIAN GLOBAL SHOW ONE SHORTWAVE TROUGH MOVING THROUGH BY 00Z SUNDAY...WHILE NAM/GFS ARE GOOD 6+ HOURS SLOWER. THOSE MODELS ARE IN BETTER AGREEMENT WITH AMPLIFYING UPPER WAVE DIVING SOUTH FROM THE NORTHWEST TERRITORIES...LEADING TO POTENTIAL CLOSED LOW AT 500 MB MOVING THROUGH LOWER MICHIGAN ON SUNDAY. AS FAR AS TEMPS GO FOR THE WEEKEND...GFS MOS MAXES ON SATURDAY LOOK A LITTLE TOO WARM WITH WEAK LOW LEVEL COLD ADVECTION DURING THE DAY AND 925 MB TEMPS FORECASTED TO DROP BELOW -3 C BY 12Z SATURDAY (BLENDING GFS/NAM). WITH CLOUDS AND SNOW SHOWERS SATURDAY NIGHT...WOULD EXPECT MINS TO HOLD IN THE TEENS TO AROUND 20. GFS MOS GUIDANCE TEMP LOOK GOOD FOR SUNDAY...UPPER TEENS TO LOWER 20S...A COUPLE DEGREES WARMER THAN YESTERDAY`S AIRMASS. YESTERDAY`S DTX SOUNDING CAME IN WITH -20 C AT 850MB...WHILE A BLEND OF THE UKMET/GFS/NAM PUTS THE 850 MB TEMP AT -18 C BY 00Z MONDAY. BROAD CYCLONIC FLOW AND LINGERING MOISTURE UP TO 700 MB STILL SUPPORTS A LOW CHANCE OF SNOW SHOWERS SUNDAY NIGHT BEFORE SHORTWAVE RIDGING MOVES THROUGH THE CENTRAL GREAT LAKES ON MONDAY. WITH THE LINGERING CLOUDS AND GRADIENT SUNDAY NIGHT...WITH LEAVE THE MINS IN THE SINGLE DIGITS. 00Z EUROPEAN/GFS/CANADIAN GLOBAL ALL SHOWING AN UPPER WAVE/TROUGH SWINGING THROUGH MONDAY NIGHT/TUESDAY...WORTHY OF A CHANCE OF LIGHT SNOW AS A SURFACE REFLECTION IS ALSO FORECASTED TO MOVE THROUGH. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054- MIZ055-MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070- MIZ075-MIZ076 UNTIL 7 PM FRIDAY. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT H SATURDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...BGM LONG TERM....SF AVIATION...CB YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1250 PM EST FRI JAN 26 2007 .UPDATE...FREEZING DRIZZLE RAPIDLY EXPANDING NORTH OVER NORTHERN LOWER MICHIGAN AS MID LEVEL MOISTURE QUICKLY PULLS OFF TO THE EAST. HERE AT THE OFFICE STEADY FREEZING DRIZZLE HAS OCCURRED OVER THE PAST HOUR WITH A GENERAL SURFACE COATING. SOUNDINGS SHOW GOOD POTENTIAL FOR AREAS OF FREEZING DRIZZLE TO SPREAD AS FAR NORTH AS THE BRIDGE...WITH MORE OF A SNOW/FREEZING DRIZZLE POTENTIAL OVER EASTERN UPPER MICHIGAN. CONDITIONS LOOK TO REMAIN UNCHANGED THROUGH THIS EVENING UNTIL LOW LEVEL MOISTURE DECREASES. THEREFORE...HAVE GONE AHEAD AND EXPANDED WINTER WEATHER ADVISORY FOR ALL OF NORTHERN MICHIGAN AND EXTENDED THE ADVISORY THROUGH MIDNIGHT...FOR A COMBINATION OF THE 1 TO 2 INCHES OF LIGHT SNOW THIS MORNING AND LIGHT FREEZING DRIZZLE THIS AFTERNOON AND EVENING. WILL LEAVE EASTERN UPPER MICHIGAN OUT OF THE ADVISORY AS SOUNDINGS REMAIN MARGINAL FOR WIDESPREAD FREEZING DRIZZLE. WILL CONTINUE TO MONITOR. MSB && .PREV DISCUSSION...ISSUED AT 1123 AM EST FRI JAN 26 2007 UPDATE...IMPRESSIVE NORTH/SOUTH 850MB-650MB THERMAL GRADIENT ESTABLISHED RIGHT OVER THE HEART OF THE FORECAST AREA THIS MORNING. WEST WINDS OF 40 TO 60 KNOTS THROUGH THIS LAYER (PER BLUE RIVER WISCONSIN PROFILER AND 12Z GREEN BAY SOUNDING) PERPENDICULARLY BISECTING TEMPERATURE GRADIENT...LEADING TO IMPRESSIVE ISENTROPIC UPGLIDE AND FRONTOGENETICAL RESPONSE. AS A RESULT...LARGE AREA OF SNOW RAPIDLY BROKE OUT THIS MORNING...WITH GENERAL ACCUMULATION OF 1 TO 2 INCHES SO FAR. LATEST RADAR/SATELLITE/RUC ANALYSIS SHOWS THIS AREA RAPIDLY ADVANCING EAST. MID LEVEL MOISTURE QUICKLY SCOURING OUT BEHIND THIS SNOWFALL WHILE LOW LEVELS (BELOW -10C) REMAIN SATURATED. FREEZING DRIZZLE ALREADY BREAKING OUT OVER PARTS OF SOUTHWEST AND SOUTH CENTRAL LOWER MICHIGAN WITH A RECENT REPORT FROM THE GRAND RAPIDS OFFICE OF LIGHT FREEZING DRIZZLE OCCURING AT BIG RAPIDS...WITH A LIGHT COATING ALREADY OBSERVED ON CARS. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER ON TIMING EXIT OF STEADY SNOW WITH PRIMARY FOCUS ON EXPANDING AREA OF LIGHT FREEZING DRIZZLE AND ASSOCIATED WINTER WEATHER HEADLINES. RADAR EXTRAPOLATION INDICATES CATEGORICAL SNOW SHOULD EXIT OFF TO THE EAST BY MID AFTERNOON...WITH PERHAPS AN ADDITIONAL INCH OF ACCUMULATION OVER EASTERN AREAS. LATEST 12Z NAM-WRF GUIDANCE CONTINUES PREVIOUS IDEA OF MID LEVEL MOISTURE RAPIDLY SCOURING OUT...LEAVING A SATURATED SOUNDING BELOW -10C. THUS...THE THREAT OF FREEZING DRIZZLE CONTINUES THIS AFTERNOON WITH SOME WIND SHEAR NOTED IN THIS LAYER ALONG WITH SOME WEAK LIFT. BIGGEST CHANGE FROM OVERNIGHT THINKING WAS TO EXPAND THIS AREA NORTH THROUGH THE ENTIRE CWA. STILL THINKING BIGGEST IMPACT AND MOST WIDESPREAD ACTIVITY WILL REMAIN OVER SOUTHERN AND SOUTHWESTERN SECTION OF THE AREA. WILL THEREFORE CONTINUE WINTER WEATHER ADVISORY THROUGH 5 PM FOR THIS AREA. WILL CONTINUE TO MONITOR TRENDS DURING THE AFTERNOON FOR ANY NEED FOR EXPANSION OF ADVISORY NORTHWARD. MARINE...SEVERAL REPORTS OF WIND GUSTS TO 25 TO 30 KNOTS OVER SOUTHERN WISCONSIN. EXPECT THIS AREA TO EXPAND NORTHWARD AS PRESSURE GRADIENT STRENGTHENS AHEAD OF ALBERTA CLIPPER DROPPING INTO WESTERN UPPER MICHIGAN. WILL ISSUE SCA FOR SOUTHERN TWO NEARSHORE ZONES OF LAKE MICHIGAN AND FOR ALL BUT SOUTHERN NEARSHORE ZONE ON LAKE HURON. MSB PREV DISCUSSION...ISSUED AT 446 AM EST FRI JAN 26 2007 WATER VAPOR IMAGERY/UPPER AIR PLOTS REVEALING DEEP LONG WAVE TROUGH AND DEPARTING CORE OF COLD AIR CENTERED ACROSS EASTERN CANADA...AND LONG WAVE RIDGE SITTING OVER WESTERN NOAM. SHORT WAVE NOTED DROPPING SE THROUGH SOUTH CENTRAL CANADA INTO THE LONG WAVE TROUGH IN THE EAST...AND THE NEXT WEATHER MAKER FOR US OVER THE NEXT 1-2 DAYS. AT THE SFC...HIGH PRESSURE EXTENDS FROM THE WESTERN GREAT LAKES TO THE SOUTHERN PLAINS THIS MORNING...WHILE LOW PRESSURE (ASSOCIATED WITH THE AFOREMENTIONED WAVE) ANALYZED NEAR LAKE WINNIPEG. WARM FRONT EXTENDS SSE FROM THE LOW INTO THE UPPER MIDWEST WHILE A COLD FRONT TRAILS BACK ACROSS THE NRN ROCKIES. REGIONAL RADAR PLOT SHOWING SOME LIGHT SNOWFALL ALONG THE TIGHTENING THERMAL GRADIENT ACROSS THE WESTERN GREAT LAKES...AHEAD OF THE WARM FRONT...TRYING TO WORK INTO THE REGION THIS MORNING...BUT LITTLE MORE THAN FLURRIES REPORTED IN OBS AT THIS POINT. FINALLY...KAPX RADAR SHOWING SOME RESIDUAL LIGHT LAKE EFFECT FLURRY ACTIVITY OVER NW LOWER MICHIGAN ON THE BACKING WEST FLOW. IMMEDIATE FORECAST CONCERN REVOLVES AROUND SNOW ACCUMULATIONS TODAY WITH A QUICK SHOT OF STRONG F-GENT/ISENTROPIC ASCENT ROLLING THROUGH THE REGION AHEAD OF THE WAVE...BOLSTERED BY ANY LAKE CONTRIBUTION. TODAY...SFC HIGH PRESSURE NOW IN CONTROL FORECAST TO QUICKLY RETREAT SOUTHWARD EARLY THIS MORNING AS UPSTREAM SFC LOW/ASSOCIATED MID LEVEL WAVE DROP INTO THE REGION. THERMAL GRADIENT ACROSS THE WESTERN GREAT LAKES FORECAST TO RAPIDLY TIGHTEN THIS MORNING WITH A NICE SHOT OF LOW-MID LEVEL ISENTROPIC ASCENT/NET ADIABATIC OMEGA SLIDING W-E THROUGH THE REGION...FOCUSED ACROSS THE WESTERN HALF OF LOWER MICHIGAN. MODEL CROSS SECTIONS TAKEN PERPENDICULAR TO THE THERMAL GRADIENT SHOWING A FOCUSED REGION OF W-E SLOPED 2-D FGEN DEVELOPING OVER NRN MICHIGAN EARLY THIS MORNING. BEST RESPONSE/MODEL OMEGA AGAIN INDICATED ACROSS THE WESTERN HALF OF LOWER MICHIGAN WITH THE MODEL OMEGA MAX INTERSECTING THE IDEAL -12C TO -18C THERMAL REGIME OVER THE W/WSW QUARTER OF THE CWA (PERHAPS AROUND HTL TO CAD IF THE MODEL IS DEAD ON). FORTUNATELY...IT DOES NOT LAST LONG...ON THE ORDER OF 3 HOURS OR SO. BUT WITHIN THAT TIMEFRAME POTENTIAL IS THERE FOR A NICE AREA OF BANDED MOD-HEAVY SNOWFALL TO DEVELOP OVER THE AREA MENTIONED AND TO GET A QUICK 1-3 INCHES OF ACCUMULATION. MEANWHILE FLOW BACKING INTO THE SW MAY ALSO GET A FEW HOURS OF LAKE ENHANCEMENT OFF LAKE MICHIGAN FROM MANISTEE UP TO LEELANAU COUNTY BEFORE THE FLOW CONTINUES ON AROUND TO THE SOUTH BY LATE MORNING. ALL TOLD...WILL UP POPS TO CATEGORICAL THIS MORNING FOR THE ENTIRE CWA BUT FOCUS BEST ACCUMULATIONS FROM HTL/GOV OVER TO MBL/FRANKFORT AND LEELANAU COUNTY. THEN...BY LATE MORNING AND INTO THE AFTERNOON FGEN/WARM ADVECTION FORCING DIMINISHES WHILE LOW-MID LEVEL MOISTURE STRIPS OUT W-E. EARLIER CONCERNS OVER FREEZING DRIZZLE IN THE AFTERNOON CERTAINLY LOOK JUSTIFIED ACROSS THE S/SW PORTION OF THE CWA AS REMAINING SATURATED LOW LEVELS ENTIRELY WARMER THAN -6C TO -8C WITH MOISTURE POKING UP ABOVE THE INVERSION (A TELLTALE DRIZZLE SOUNDING). THERMAL PROFILES REMAIN JUST COLD ENOUGH FOR -FZDZ/-SN THE FURTHER NORTH YOU GO AND JUST SNOW IN EASTERN UPPER. SO...WITH MORNING SNOWFALL OF 1-3 INCHES (POSSIBLY BETTER) COMBINED WITH AFTERNOON FREEZING DRIZZLE...PROBABLY ENOUGH TO WARRANT A WINTER WEATHER ADVISORY TODAY ACROSS THE S/SW PART OF THE CWA. TONIGHT...SFC LOW EXPECTED TO DROP DOWN ACROSS THE EASTERN HALF OF THE STATE...WITH WINDS TURNING NW AND COLDER AIR ONCE AGAIN OOZING INTO THE REGION. STILL FAIRLY DRY ALOFT AND SHALLOW SATURATED LOWER LAYERS WARMER THAN -10C REMAIN A CONCERN OVER THE SRN HALF OF THE CWA DURING THE EVENING HOURS WITH PATCHY FREEZING DRIZZLE POSSIBLE...ALTHOUGH SHRINKING INVERSION HEIGHTS AND MOISTURE DEPTH MAY DIMINISH THE THREAT. WILL NOT CARRY THE ADVISORY INTO THE EVENING HOURS WITH THAT THOUGHT IN MIND BUT DAY SHIFT WILL WANT TO CONSIDER EXTENDING ADVISORIES IF NEED BE. WILL KEEP LIGHT SNOW CHANCES GOING ACROSS EASTERN UPPER MICHIGAN WHERE COLDEST THERMAL PROFILE RESIDES. MAY ACTUALLY SEE SOME DECENT SNOW SHOWERS OFF LAKE HURON UP THROUGH THE SAINT MARYS SYSTEM THIS EVENING WITH SE LOW LEVEL FLOW. EVENING SHIFT WILL WANT TO WATCH FOR THAT. THEN...WITH WINDS TURNING NW...COLDER AIR FILTERING DOWN INTO THE REGION OVERNIGHT...FREEZING DRIZZLE SHOULD FINALLY COME TO AN END FOR MOST AREAS WITH LAKE EFFECT SNOW SHOWERS BECOMING MORE PROMINENT OFF LAKES MICHIGAN AND SUPERIOR. SATURDAY AND SATURDAY NIGHT...LOW PRESSURE SYSTEM CONTINUES TO SLOWLY PULL AWAY EAST OF THE STATE WHILE SHARP LOW LEVEL TROUGHING LINGERS BACK ACROSS THE UPPER PENINSULA. MODELS INSIST ON DRAGGING THE TROUGH/COLD FRONT DOWN THROUGH LOWER MICHIGAN SATURDAY NIGHT WITH SUBSTANTIALLY COLDER AIR THEN ARRIVING FOR THE LATTER HALF OF THE WEEKEND. WILL SEE HOW THAT PLAYS OUT AS THE MODELS OFTEN ARE TOO FAST WITH THIS SCENARIO (I.E. SFC TROUGH HOLDS ACROSS THE NORTH MUCH LONGER THAN FORECAST). AT ANY RATE...WILL KEEP SCT-NUMEROUS SNOW SHOWERS GOING FOR SATURDAY WITH HIGHEST POPS OVER THE NW FLOW AREAS AHEAD OF THE TROUGH. BEST ACCUMULATIONS ON SATURDAY MAY BE FOUND ACROSS THE U.P. AND EASTERN UPPER MICHIGAN WITH THE SHARP TROUGH/STRONG LOW LEVEL CONVERGENCE ACROSS THIS AREA. THEN FOR SATURDAY NIGHT...IF TROUGH MANAGES TO DROP SOUTH FOLLOWED BY MUCH COLDER AIR AND WINDS TURNING INTO THE NORTH...POSSIBILITIES FOR ANOTHER GOOD LAKE EFFECT EVENT AROUND THE GRAND TRAVERSE BAY REGION OVERNIGHT INTO SUNDAY. SUNDAY THROUGH TUESDAY...NO SIGNIFICANT CHANCES MADE TO THE FORECAST. OVERALL...COLD WEATHER PATTERN REMAINS LOCKED IN PLACE INTO EARLY NEXT WEEK. MAIN FORECAST ISSUES WILL BE TIMING ADDITIONAL WAVES THROUGH THE REGION AND PINPOINTING SYNOPTIC/LAKE EFFECT THROUGH TUESDAY. PERHAPS A BRIEF BREAK ON MONDAY AS HIGH PRESSURE SCOOTS THROUGH THE REGION...ALREADY REFLECTED IN THE FORECAST WITH JUST LOW CHANCY POPS. ANOTHER CLIPPER TYPE SYSTEM CURRENTLY SLATED FOR TUESDAY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY... TODAY AND THIS EVENING...MIZ016-036>041-042. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1200 PM EST FRI JAN 26 2007 .UPDATE... MID-LVL DRYING IN ADVANCE OF CLIPPER SHORTWAVE MOVING DOWN FROM MANITOBA HAS EXTENDED A BIT FARTHER E OVER THE FCST AREA AS NOTED ON 12Z NAM AND RUC SNDGS AND CONFIRMED BY LOCAL TAMDAR SNDGS. THUS...HAVE TRIMMED BACK POPS TO LOW CHC OVER MUCH OF THE ERN FCST AREA AND ALSO SPREAD POTENTIAL FOR FLURRIES/FZDZ MIX INTO THESE COUNTIES AS WELL. SNDG PROFILE SUGGEST POTENTIAL FOR POSSIBLE FZDZ GIVEN MID-LVL DRYING AND LOW-LVL MOISTURE BARELY REACHING TOWARD -10C ISOTHERM. WRESTLED A BIT WITH IDEA OF TAKING SNOW ADVISORY DOWN FOR SRN SCHOOLCRAFT COUNTY GIVEN DEGREE OF MID-LVL DRYING AND MARGINALLY COLD TEMPS FOR DECENT LAKE ENHANCEMENT. HOWEVER...RUC AND NAM MODELS STILL INDICATE GOOD LOW-LVL CONVERGENCE FOCUSED OVER SRN SCHOOLCRAFT COUNTY THIS AFTERNOON SO IN THE END DECIDED TO KEEP THE ADVISORY HEADLINE GOING AND MENTIONED ADDITIONAL SNOW ACCUMS OF 1-3". && .PREV DISCUSSION... THERE ARE TWO BIG FCST CONCERNS EARLY THIS MORNING. FIRST IS LAKE ENHANCEMENT POTENTIAL IN SRLY FLOW OFF LAKE MICHIGAN. SECOND CONCERN REVOLVES AROUND UPCOMING HEADLINE LAKE EFFECT EVENT SAT/SUN. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP VORTEX DESCENDING OVER NEW ENGLAND. NW FLOW AROUND THE WRN SIDE OF THIS VORTEX IS DOMINATING THE GREAT LAKES REGION EARLY THIS MORNING. MEANWHILE... UPSTREAM A FAIRLY IMPRESSIVE LOOKING SHORTWAVE IS HEADING SE THRU SASKATCHEWAN. 00Z SOUNDING FROM CWEG IN ALBERTA SHOWED A RESPECTABLE 12HR 500MB HEIGHT FALL OF 140M WITH THIS SYSTEM. AHEAD OF THE SHORTWAVE...POOL OF VERY WARM AIR DUE MOSTLY TO DOWNSLOPING OFF THE ROCKIES HAS PUSHED OUT OVER THE NRN PLAINS. 00Z RAOBS SHOWED 850MB TEMPS ALL THE WAY UP TO 11C AT KBIS AND 14C AT KUNR. THIS WAA HAS LED TO A BAND OF MID CLOUDS ACROSS THE UPPER MIDWEST/WRN GREAT LAKES REGION...AND SATELLITE AND REGIONAL RADAR IMAGERY SHOW CONVECTIVE ELEMENTS IN THE CLOUD BAND. 00Z KINL SOUNDING DID SHOW DRY-ADIABATIC LAPSE RATE BTWN 650 AND 550MB. SO FAR...ONLY SPOTTY -SN/FLURRIES HAVE BEEN NOTED. LACK OF PCPN IS DUE TO DRY AIRMASS PER 00Z KINL/KGRB SOUNDINGS. DRY AIR IS NOT TOO SUBSTANTIAL THOUGH AND WOULD EXPECT PCPN COVERAGE TO GRADUALLY INCREASE WITH TIME. MODELS ARE IN GOOD AGREEMENT TAKING SHORTWAVE OVER SASKATCHEWAN TO JUST NW OF LAKE SUPERIOR BY 00Z SAT. ON THIS TRACK...IMPRESSIVE DEEP LAYER FORCING INDICATED BY NAM/GFS 850/500MB QVECTOR CONVERGENCE WILL PASS JUST NE OF UPPER MI THIS EVENING. EVEN SO...NW-SE ORIENTED MODEST DEEP LAYER FORCING WILL CONTINUE ALL DAY ACROSS MOST OF THE FCST AREA. AS THE SHORTWAVE APPROACHES...BROAD/ELONGATED SFC LOW PRES CURRENTLY OVER MANITOBA WILL SLIDE ESE TO CNTRL UPPER MI/NW LAKE SUPERIOR. GIVEN FORCING AND LOCATION OF STRENGTHENING LOW-LEVEL CONVERGENCE ACROSS CNTRL UPPER MI ALONG SFC TROF/WARM FRONT EXTENDING SE FROM APPROACHING LOW PRES...EXPECT MORE PERSISTENT -SN TO TAKE SHAPE OVER ROUGHLY THE E HALF OF FCST AREA TODAY. STRONG ISENTROPIC ASCENT (290K SFC OR ROUGHLY 700-750MB) IS SET FOR THE MORNING HRS THOUGH...SO HEAVIER SNOW SHOULD OCCUR THIS MORNING. THIS BRINGS UP THE PROSPECT FOR LAKE ENHANCEMENT OVER THE SE FCST AREA AS 850MB TEMPS WILL STILL BE ON THE ORDER OF -9 TO -12C OVER NRN LAKE MICHIGAN THIS MORNING AT THE TIME OF BEST FORCING. AT FIRST GLANCE...THERE WOULD APPEAR TO BE SOME CONCERN THAT THE STRONG WAA WOULD CUT OFF LAKE ENHANCEMENT POTENTIAL (00Z KMPX SOUNDING SHOWED 850MB TEMP OF ONLY -2C). HOWEVER...COOLING THRU UPWARD MOTION IN INTIAL DRY AIRMASS AND EVAPORATIVE COOLING SHOULD TEND TO SLOW THE ACTUAL WARMING AS MODELS INDICATE. AT THE LOW-LEVELS SRLY FLOW BECOMES CONVERGENT INTO SCHOOLCRAFT COUNTY AS SFC TROF DEVELOPS TOWARD NRN LAKE MICHIGAN. HAVE THUS OPTED TO ISSUE A SNOW ADVY (2-4 INCHES) FOR SRN SCHOOLCRAFT COUNTY WHERE BEST FETCH ACROSS THE LAKE TAKES AIM. CONSIDERED DELTA COUNTY...BUT WITH SHARP CONVERGENCE TO SET UP JUST E OF THERE...EXPECT LIGHTER SNOW ACCUMULATIONS. NONETHELESS...WILL NEED TO KEEP AN EYE ON THE FAR ERN PART OF DELTA COUNTY IN CASE SRLY FLOW BACKS MORE THAN EXPECTED BEFORE BEST FORCING DEPARTS. WILL BUFFER THE ADVY AREA WITH ROUGHLY 1-3 INCHES OF SNOW FROM ERN DELTA INTO ALGER/LUCE. GIVEN THE CONVECTIVE LOOK TO CLOUDS UPSTREAM...WILL NEED TO WATCH FOR SOME BURSTS OF HEAVIER SNOW AS STEEP MIDLEVEL LAPSE RATES SPREAD OVER THE AREA THIS MORNING. AFTER SOME MORNING -SN/FLURRIES WEST...POTENTIAL FOR FZDZ DEVELOPS AS MIDLEVEL MOISTURE EXITS LEAVING MOIST LAYER EXTENDING TO NEAR THE -10C ISOTHERM. SW HALF OF FCST AREA APPEARS MOST AT THREAT FOR SPOTTY -FZDZ WITH WARMER MOIST LAYER TEMPS...AND WILL INCLUDE MENTION THERE. SHORTWAVE TRACKS ACROSS LAKE SUPERIOR TONIGHT...KEEPING BEST FORCING TO THE NE OF HERE. IN FACT...MODELS ACTUALLY SHOW STRONG SUBSIDENCE OVER MUCH OF THE FCST AREA FOR A GOOD PORTION OF TONIGHT. SO...AFTER SOME EVENING -SN OVER THE FAR E...THERE MAY NOT BE MUCH IF ANY PCPN AGAIN UNTIL LATE. THIS BRING US TO THE UPCOMING LAKE EFFECT EVENT. BROAD SFC LOW PRES OVER CNTRL UPPER MI/NW LAKE SUPERIOR THIS EVENING WILL SHIFT TO LAKE HURON/ERN LAKE SUPERIOR BY 12Z SAT. ANOTHER SHORTWAVE DROPPING SE WILL THEN SEND SFC LOW/TROF S ACROSS UPPER MI SAT. THE EXACT DETAILS OF HOW THIS WILL PLAY OUT IS UNCERTAIN. GFS INDICATES SHARP SFC TROF REACHING THE KEWEENAW AROUND 12Z...THEN CLEARING NRN UPPER MI BY 18Z SAT. NAM IS ABOUT 6HRS SLOWER. RUC13 AND REGIONAL CANADIAN MODEL ARE NEARLY IDENTICAL IN SHOWING EVEN SHARPER SFC TROFFING AND HINT AT MESOLOW OVER CNTRL LAKE SUPERIOR AT 12Z N OF STANNARD ROCK. MESOLOW THEN DROPS TO NEAR MUNISING BY 18Z. SO...TIMING IS ESSENTIALLY BTWN THE GFS AND NAM. SINCE THE REGIONAL CANADIAN OFTEN DID A MUCH BETTER JOB HANDLING WIND FIELDS OVER THE LAKE IN PAST EVENTS THIS SEASON WHEN THERE WERE SHARP CONVERGENCE ZONES OVER LAKE SUPERIOR (SEVERAL IN EARLY DEC)...WILL FAVOR ITS SOLUTION WITH REGARD TO DETAILS OF WIND FIELDS. OF COURSE...PAST PERFORMANCE IS NO GUARANTEE OF FUTURE PERFORMANCE...BUT IT DOES HAVE STRONG SUPPORT FROM THE RUC13. THIS SOLUTION RESULTS IN NW FLOW INTO WRN UPPER MI OVERNIGHT AS CAA GETS UNDERWAY...BUT IT WILL PROBABLY BE AFTER 12Z BEFORE LAKE ENHANCEMENT BEGINS IN ASSOCIATION WITH NEXT APPROACHING SHORTWAVE. WILL BRING IN -SHSN OVER THE W AND N OVERNIGHT AS 850MB TEMPS DROP TO -14C OR SO BY 12Z. AS MESOLOW/SFC TROF DROP S INTO NRN UPPER MI DURING THE LATE MORNING INTO AFTN...EXPECT WIND SHIFT TO BE ACCOMPANIED BY A BAND OF HVY SNOW AS FCST SOUNDINGS INDICATING DEEP MOISTURE TO 10KFT OR MORE AND NO INVERSION. SNOW COULD BE QUITE INTENSE OVER NCNTRL UPPER MI IF MESOLOW DOES FORM ON SFC TROF. IN THE WAKE OF WIND SHIFT... CONDITIONS LOOK FAVORABLE FOR MDT/HVY LAKE ENHANCED SNOW TRANSITIONING TO PURE LES FOR N WIND FAVORED SNOWBELTS SAT AFTN THRU SAT NIGHT BEFORE SHARP DRYING AND CRASHING OF INVERSION TO 4-5KFT OCCURS EARLY SUN. WILL LEAVE GOING WATCHES AS IS (GOGEBIC/ONTONAGON/MARQUETTE/ALGER) GIVEN UNCERTAINTY ON INITIAL WIND FIELDS AND ON START TIME OF HVY SNOW...BUT IT DOES LOOK LIKE WATCHES WILL BE ABLE TO TRANSITION TO WARNINGS BASED ON VERY FAVORABLE LOOK OF FCST SOUNDINGS. ONE CHANGE WILL BE TO ADD BARAGA COUNTY TO WATCH AS N WIND DURING LAKE ENHANCEMENT PERIOD WILL FAVOR THAT AREA FOR HVY SNOW AS WELL. HOUGHTON/KEWEENAW/LUCE WILL LIKELY NEED ADVYS FOR THIS EVENT. ADVY TYPE SNOW MAY ALSO SPREAD AS FAR S AS DELTA COUNTY SAT NIGHT UNDER NRLY FLOW. && .MQT WATCHES/WARNINGS/ADVISORIES... SNOW ADVY TODAY MIZ014. LAKE EFFECT SNOW WATCH LATE TONIGHT THRU SUN MORNING MIZ002-009. LAKE EFFECT SNOW WATCH SAT MORNING THRU SUN MORNING MIZ004. LAKE EFFECT SNOW WATCH SAT MORNING THRU SUN AFTN MIZ005-006. && $$ VOSS (UPDATE) ROLFSON (PREV DISCUSSION) mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1123 AM EST FRI JAN 26 2007 .UPDATE...IMPRESSIVE NORTH/SOUTH 850MB-650MB THERMAL GRADIENT ESTABLISHED RIGHT OVER THE HEART OF THE FORECAST AREA THIS MORNING. WEST WINDS OF 40 TO 60 KNOTS THROUGH THIS LAYER (PER BLUE RIVER WISCONSIN PROFILER AND 12Z GREEN BAY SOUNDING) PERPENDICULARLY BISECTING TEMPERATURE GRADIENT...LEADING TO IMPRESSIVE ISENTROPIC UPGLIDE AND FRONTOGENETICAL RESPONSE. AS A RESULT...LARGE AREA OF SNOW RAPIDLY BROKE OUT THIS MORNING...WITH GENERAL ACCUMULATION OF 1 TO 2 INCHES SO FAR. LATEST RADAR/SATELLITE/RUC ANALYSIS SHOWS THIS AREA RAPIDLY ADVANCING EAST. MID LEVEL MOISTURE QUICKLY SCOURING OUT BEHIND THIS SNOWFALL WHILE LOW LEVELS (BELOW -10C) REMAIN SATURATED. FREEZING DRIZZLE ALREADY BREAKING OUT OVER PARTS OF SOUTHWEST AND SOUTH CENTRAL LOWER MICHIGAN WITH A RECENT REPORT FROM THE GRAND RAPIDS OFFICE OF LIGHT FREEZING DRIZZLE OCCURING AT BIG RAPIDS...WITH A LIGHT COATING ALREADY OBSERVED ON CARS. FORECAST CONCERNS FOR THE REMAINDER OF THE DAY CENTER ON TIMING EXIT OF STEADY SNOW WITH PRIMARY FOCUS ON EXPANDING AREA OF LIGHT FREEZING DRIZZLE AND ASSOCIATED WINTER WEATHER HEADLINES. RADAR EXTRAPOLATION INDICATES CATEGORICAL SNOW SHOULD EXIT OFF TO THE EAST BY MID AFTERNOON...WITH PERHAPS AN ADDITIONAL INCH OF ACCUMULATION OVER EASTERN AREAS. LATEST 12Z NAM-WRF GUIDANCE CONTINUES PREVIOUS IDEA OF MID LEVEL MOISTURE RAPIDLY SCOURING OUT...LEAVING A SATURATED SOUNDING BELOW -10C. THUS...THE THREAT OF FREEZING DRIZZLE CONTINUES THIS AFTERNOON WITH SOME WIND SHEAR NOTED IN THIS LAYER ALONG WITH SOME WEAK LIFT. BIGGEST CHANGE FROM OVERNIGHT THINKING WAS TO EXPAND THIS AREA NORTH THROUGH THE ENTIRE CWA. STILL THINKING BIGGEST IMPACT AND MOST WIDESPREAD ACTIVITY WILL REMAIN OVER SOUTHERN AND SOUTHWESTERN SECTION OF THE AREA. WILL THEREFORE CONTINUE WINTER WEATHER ADVISORY THROUGH 5 PM FOR THIS AREA. WILL CONTINUE TO MONITOR TRENDS DURING THE AFTERNOON FOR ANY NEED FOR EXPANSION OF ADVISORY NORTHWARD. MARINE...SEVERAL REPORTS OF WIND GUSTS TO 25 TO 30 KNOTS OVER SOUTHERN WISCONSIN. EXPECT THIS AREA TO EXPAND NORTHWARD AS PRESSURE GRADIENT STRENGTHENS AHEAD OF ALBERTA CLIPPER DROPPING INTO WESTERN UPPER MICHIGAN. WILL ISSUE SCA FOR SOUTHERN TWO NEARSHORE ZONES OF LAKE MICHIGAN AND FOR ALL BUT SOUTHERN NEARSHORE ZONE ON LAKE HURON. MSB && .PREV DISCUSSION...ISSUED AT 446 AM EST FRI JAN 26 2007 WATER VAPOR IMAGERY/UPPER AIR PLOTS REVEALING DEEP LONG WAVE TROUGH AND DEPARTING CORE OF COLD AIR CENTERED ACROSS EASTERN CANADA...AND LONG WAVE RIDGE SITTING OVER WESTERN NOAM. SHORT WAVE NOTED DROPPING SE THROUGH SOUTH CENTRAL CANADA INTO THE LONG WAVE TROUGH IN THE EAST...AND THE NEXT WEATHER MAKER FOR US OVER THE NEXT 1-2 DAYS. AT THE SFC...HIGH PRESSURE EXTENDS FROM THE WESTERN GREAT LAKES TO THE SOUTHERN PLAINS THIS MORNING...WHILE LOW PRESSURE (ASSOCIATED WITH THE AFOREMENTIONED WAVE) ANALYZED NEAR LAKE WINNIPEG. WARM FRONT EXTENDS SSE FROM THE LOW INTO THE UPPER MIDWEST WHILE A COLD FRONT TRAILS BACK ACROSS THE NRN ROCKIES. REGIONAL RADAR PLOT SHOWING SOME LIGHT SNOWFALL ALONG THE TIGHTENING THERMAL GRADIENT ACROSS THE WESTERN GREAT LAKES...AHEAD OF THE WARM FRONT...TRYING TO WORK INTO THE REGION THIS MORNING...BUT LITTLE MORE THAN FLURRIES REPORTED IN OBS AT THIS POINT. FINALLY...KAPX RADAR SHOWING SOME RESIDUAL LIGHT LAKE EFFECT FLURRY ACTIVITY OVER NW LOWER MICHIGAN ON THE BACKING WEST FLOW. IMMEDIATE FORECAST CONCERN REVOLVES AROUND SNOW ACCUMULATIONS TODAY WITH A QUICK SHOT OF STRONG F-GENT/ISENTROPIC ASCENT ROLLING THROUGH THE REGION AHEAD OF THE WAVE...BOLSTERED BY ANY LAKE CONTRIBUTION. TODAY...SFC HIGH PRESSURE NOW IN CONTROL FORECAST TO QUICKLY RETREAT SOUTHWARD EARLY THIS MORNING AS UPSTREAM SFC LOW/ASSOCIATED MID LEVEL WAVE DROP INTO THE REGION. THERMAL GRADIENT ACROSS THE WESTERN GREAT LAKES FORECAST TO RAPIDLY TIGHTEN THIS MORNING WITH A NICE SHOT OF LOW-MID LEVEL ISENTROPIC ASCENT/NET ADIABATIC OMEGA SLIDING W-E THROUGH THE REGION...FOCUSED ACROSS THE WESTERN HALF OF LOWER MICHIGAN. MODEL CROSS SECTIONS TAKEN PERPENDICULAR TO THE THERMAL GRADIENT SHOWING A FOCUSED REGION OF W-E SLOPED 2-D FGEN DEVELOPING OVER NRN MICHIGAN EARLY THIS MORNING. BEST RESPONSE/MODEL OMEGA AGAIN INDICATED ACROSS THE WESTERN HALF OF LOWER MICHIGAN WITH THE MODEL OMEGA MAX INTERSECTING THE IDEAL -12C TO -18C THERMAL REGIME OVER THE W/WSW QUARTER OF THE CWA (PERHAPS AROUND HTL TO CAD IF THE MODEL IS DEAD ON). FORTUNATELY...IT DOES NOT LAST LONG...ON THE ORDER OF 3 HOURS OR SO. BUT WITHIN THAT TIMEFRAME POTENTIAL IS THERE FOR A NICE AREA OF BANDED MOD-HEAVY SNOWFALL TO DEVELOP OVER THE AREA MENTIONED AND TO GET A QUICK 1-3 INCHES OF ACCUMULATION. MEANWHILE FLOW BACKING INTO THE SW MAY ALSO GET A FEW HOURS OF LAKE ENHANCEMENT OFF LAKE MICHIGAN FROM MANISTEE UP TO LEELANAU COUNTY BEFORE THE FLOW CONTINUES ON AROUND TO THE SOUTH BY LATE MORNING. ALL TOLD...WILL UP POPS TO CATEGORICAL THIS MORNING FOR THE ENTIRE CWA BUT FOCUS BEST ACCUMULATIONS FROM HTL/GOV OVER TO MBL/FRANKFORT AND LEELANAU COUNTY. THEN...BY LATE MORNING AND INTO THE AFTERNOON FGEN/WARM ADVECTION FORCING DIMINISHES WHILE LOW-MID LEVEL MOISTURE STRIPS OUT W-E. EARLIER CONCERNS OVER FREEZING DRIZZLE IN THE AFTERNOON CERTAINLY LOOK JUSTIFIED ACROSS THE S/SW PORTION OF THE CWA AS REMAINING SATURATED LOW LEVELS ENTIRELY WARMER THAN -6C TO -8C WITH MOISTURE POKING UP ABOVE THE INVERSION (A TELLTALE DRIZZLE SOUNDING). THERMAL PROFILES REMAIN JUST COLD ENOUGH FOR -FZDZ/-SN THE FURTHER NORTH YOU GO AND JUST SNOW IN EASTERN UPPER. SO...WITH MORNING SNOWFALL OF 1-3 INCHES (POSSIBLY BETTER) COMBINED WITH AFTERNOON FREEZING DRIZZLE...PROBABLY ENOUGH TO WARRANT A WINTER WEATHER ADVISORY TODAY ACROSS THE S/SW PART OF THE CWA. TONIGHT...SFC LOW EXPECTED TO DROP DOWN ACROSS THE EASTERN HALF OF THE STATE...WITH WINDS TURNING NW AND COLDER AIR ONCE AGAIN OOZING INTO THE REGION. STILL FAIRLY DRY ALOFT AND SHALLOW SATURATED LOWER LAYERS WARMER THAN -10C REMAIN A CONCERN OVER THE SRN HALF OF THE CWA DURING THE EVENING HOURS WITH PATCHY FREEZING DRIZZLE POSSIBLE...ALTHOUGH SHRINKING INVERSION HEIGHTS AND MOISTURE DEPTH MAY DIMINISH THE THREAT. WILL NOT CARRY THE ADVISORY INTO THE EVENING HOURS WITH THAT THOUGHT IN MIND BUT DAY SHIFT WILL WANT TO CONSIDER EXTENDING ADVISORIES IF NEED BE. WILL KEEP LIGHT SNOW CHANCES GOING ACROSS EASTERN UPPER MICHIGAN WHERE COLDEST THERMAL PROFILE RESIDES. MAY ACTUALLY SEE SOME DECENT SNOW SHOWERS OFF LAKE HURON UP THROUGH THE SAINT MARYS SYSTEM THIS EVENING WITH SE LOW LEVEL FLOW. EVENING SHIFT WILL WANT TO WATCH FOR THAT. THEN...WITH WINDS TURNING NW...COLDER AIR FILTERING DOWN INTO THE REGION OVERNIGHT...FREEZING DRIZZLE SHOULD FINALLY COME TO AN END FOR MOST AREAS WITH LAKE EFFECT SNOW SHOWERS BECOMING MORE PROMINENT OFF LAKES MICHIGAN AND SUPERIOR. SATURDAY AND SATURDAY NIGHT...LOW PRESSURE SYSTEM CONTINUES TO SLOWLY PULL AWAY EAST OF THE STATE WHILE SHARP LOW LEVEL TROUGHING LINGERS BACK ACROSS THE UPPER PENINSULA. MODELS INSIST ON DRAGGING THE TROUGH/COLD FRONT DOWN THROUGH LOWER MICHIGAN SATURDAY NIGHT WITH SUBSTANTIALLY COLDER AIR THEN ARRIVING FOR THE LATTER HALF OF THE WEEKEND. WILL SEE HOW THAT PLAYS OUT AS THE MODELS OFTEN ARE TOO FAST WITH THIS SCENARIO (I.E. SFC TROUGH HOLDS ACROSS THE NORTH MUCH LONGER THAN FORECAST). AT ANY RATE...WILL KEEP SCT-NUMEROUS SNOW SHOWERS GOING FOR SATURDAY WITH HIGHEST POPS OVER THE NW FLOW AREAS AHEAD OF THE TROUGH. BEST ACCUMULATIONS ON SATURDAY MAY BE FOUND ACROSS THE U.P. AND EASTERN UPPER MICHIGAN WITH THE SHARP TROUGH/STRONG LOW LEVEL CONVERGENCE ACROSS THIS AREA. THEN FOR SATURDAY NIGHT...IF TROUGH MANAGES TO DROP SOUTH FOLLOWED BY MUCH COLDER AIR AND WINDS TURNING INTO THE NORTH...POSSIBILITIES FOR ANOTHER GOOD LAKE EFFECT EVENT AROUND THE GRAND TRAVERSE BAY REGION OVERNIGHT INTO SUNDAY. SUNDAY THROUGH TUESDAY...NO SIGNIFICANT CHANCES MADE TO THE FORECAST. OVERALL...COLD WEATHER PATTERN REMAINS LOCKED IN PLACE INTO EARLY NEXT WEEK. MAIN FORECAST ISSUES WILL BE TIMING ADDITIONAL WAVES THROUGH THE REGION AND PINPOINTING SYNOPTIC/LAKE EFFECT THROUGH TUESDAY. PERHAPS A BRIEF BREAK ON MONDAY AS HIGH PRESSURE SCOOTS THROUGH THE REGION...ALREADY REFLECTED IN THE FORECAST WITH JUST LOW CHANCY POPS. ANOTHER CLIPPER TYPE SYSTEM CURRENTLY SLATED FOR TUESDAY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES...WINTER WEATHER ADVISORY... TODAY...MIZ020-025>028-031>035-041-042. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1036 AM EST FRI JAN 26 2007 .UPDATE... SNOW HAS INCREASED IN INTENSITY THIS MORNING WITH VISIBILITIES DOWN TO LESS THAN 1 MILE. NICE FGEN FORCING PER THE 12Z RUC ON THE 750MB SURFACE WHICH SLIDES NORTHEAST OF THE CWA BETWEEN 17Z-18Z. FURTHERMORE...ADDITIONAL LIFT FROM THE ENTRANCE REGION OF 130KT JET CENTERED OVER BUFFALO NY IS AIDING IN ADDITIONAL LIFT. IMPRESSIVE WARM ADVECTION AND MID LEVEL DRY SLOT IS STILL EXPECTED TO MOVE ACROSS THE REGION THIS AFTERNOON. BASED ON SOUNDINGS FROM THE RUC AND THE ARRIVAL OF THE NEW NAM...FREEZING DRIZZLE LOOKS GOOD AS WE LOSE MOISTURE AT THE DENDRITIC ICE GROWTH REGION. TEMPERATURES WILL CONTINUE TO CLIMB THROUGH THE 20S AND MIGHT CONTINUE TO RISE THROUGH THE NIGHT... && .PREV DISCUSSION...ISSUED 600 AM EST FRI JAN 26 2007 AVIATION... CONDITIONS WILL GENERALLY DETERIORATE DURING THE FIRST PART OF THE FORECAST AS AN AREA OF LIGHT SNOW ASSOCIATED WITH MODERATE/STRONG WARM AIR ADVECTION EVENTUALLY OVERCOMES DRY LOW LEVELS AND REACHES THE GROUND EARLY THIS MORNING. THIS WILL BRING LOWERING VISIBILITIES AND CEILINGS IN THE MVFR RANGE BY AND LARGE. AFTER THE INITIAL SURGE OF MOISTURE AND SNOW...DRY AIR WORKS INTO THE MID LEVELS AND LEADS TO A TRANSITION OF LIGHT SNOW/FREEZING DRIZZLE AND THEN ALL FREEZING DRIZZLE DURING THE AFTERNOON. WOULD EXPECT CEILINGS TO CONTINUE TO LOWER AND WOULD NOT BE AT ALL SURPRISED IF THE IFR CONDITIONS OVER WISCONSIN MADE IT THIS FAR EAST LATE TODAY. THIS WHOLE SCENARIO IS BEING DRIVEN BY LOW PRESSURE TRACKING THROUGH THE NORTHERN GREAT LAKES. AS THIS LOW MOVES INTO LAKE HURON LATE TONIGHT...COLD AIR WILL SURGE BACK SOUTH INTO THE AREA...BRINGING ANY LEFTOVER DRIZZLE OR FREEZING DRIZZLE BACK TO LIGHT SNOW SHOWERS AFTER BY 06Z OR SO. PREV DISCUSSION...ISSUED AT 341 AM SHORT TERM...TODAY AND TONIGHT TRICKY FORECAST TODAY AS A BAND OF LIGHT SNOW SPREADS INTO THE AREA THIS MORNING IN WARM AIR ADVECTION REGIME. THIS SNOW WILL AMOUNT TO AN INCH OR TWO...WITH THE BEST ACCUMULATION POTENTIAL ALONG AND TO THE NORTHEAST OF I-75 OR SO. THERE WILL BE A SHARP CUTOFF IN LIGHT SNOW ACCUMULATION TO THE SOUTHWEST AS DRY AIR WORKS QUICKLY INTO THE AREA WITHIN INCREASING SOUTHWEST FLOW REGIME. THIS INTRUSION OF DRY AIR WILL FIRST STRIP AWAY MID AND UPPER LEVEL MOISTURE...LEADING TO PRECIPITATION CHANGING OVER FROM LIGHT SNOW TO FREEZING DRIZZLE AS SEMI-SATURATED PORTION OF THE ATMOSPHERE BECOMES LIMITED TO AREAS BELOW 800 MB...AND BELOW -10C...THUS LIMITING THE POTENTIAL FOR ICE NUCLEATION AND SNOWFLAKE PRODUCTION. WITHIN THIS PROCESS...THE DRY SLOT MAY EVEN ELIMINATE ENOUGH OF THE LOW LEVEL MOISTURE TO END OR AT LEAST LIMIT THE AMOUNT OF DRIZZLE OVER THE SOUTHERN CWA...ESPECIALLY BY AFTERNOON. WITH THIS MIXTURE OF PRECIPITATION...AND AFTER COORDINATION WITH SURROUNDING OFFICES...WILL BE GOING WITH A WINTER WEATHER ADVISORY TODAY FOR ALL BUT THE SOUTHERNMOST TWO COUNTIES IN THE CWA. THE SOUTHERN EDGE OF THIS ADVISORY WILL HAVE THE LIGHTEST PRECIPITATION BUT MOST FREEZING DRIZZLE POTENTIAL -VS- LIGHT SNOW...AND THE NORTHEAST THUMB REGION WILL HAVE BETTER SNOW ACCUMULATION...BUT LIMITED FREEZING DRIZZLE THROUGH THIS AFTERNOON. ALL IN ALL...THE PRECIPITATION WILL BE LIGHT...BUT WITH SURFACE TEMPERATURES IN THE SINGLE DIGITS TO TEENS AT THE START OF THE EVENT...THE DRIZZLE BY LATE MORNING/EARLY AFTERNOON WILL HAVE LITTLE PROBLEM FREEZING TO SURFACES. WILL LIMIT THE ADVISORY TO THE FIRST PERIOD AND ALLOW THE DAYSHIFT TO EVALUATE JUST HOW MUCH PRECIPITATION WILL CONTINUE INTO THIS EVENING. AT THIS TIME...IT APPEARS THE MOST WIDESPREAD FREEZING DRIZZLE AND/OR LIGHT SNOW BY THIS EVENING WILL BE LIMITED TO AREAS ALONG/NORTH OF I-69 OR PERHAPS THE M-59 CORRIDOR. THE ADVISORY MAY VERY WELL NEED TO BE EXTENDED INTO TONIGHT IN SOME AREAS. LONG TERM... NEXT SURGE OF ARCTIC AIR TO IMPACT SOUTHEAST MICHIGAN THIS WEEKEND...LIKELY LEADING TO ANOTHER ROUND OF ACCUMULATING SNOW...ESPECIALLY ACROSS THE THUMB REGION. TOO FAR OUT TO PIN DOWN THE DETAILS OF ANY LAKE HURON BANDS...AS TIMING AND STRENGTH OF UPPER WAVES AS SEEN ON DYNAMIC TROPOPAUSE VARY BETWEEN 00Z UKMET/NAM AND GFS. HOWEVER...WITH ALL MODELS SHOWING A WELL DEFINED SURFACE TROUGH LINGERING ACROSS SOUTHERN LOWER MICHIGAN AND 850 MB TEMPS FALLING TO AT LEAST -18 C...SNOW SHOWERS APPEAR TO BE A GOOD BET AND HAVE RAISED POPS TO 50 PERCENT SATURDAY NIGHT AND SUNDAY ACROSS MOST OF SOUTHEAST MICHIGAN...WITH LIKELY POPS ACROSS THE THUMB REGION BY SUNDAY. POPS FOR ONE OR BOTH OF THOSE PERIODS WILL PROBABLY HAVE TO BE BUMPED UP AS TIMING OF THE UPPER WAVES BECOME CLEARER. WATER VAPOR IMAGERY SHOW A LARGE UPPER LEVEL CIRCULATION OVER CENTRAL CANADA (ALBERTA/SASKATCHEWAN/MANITOBA) WITH MULTIPLE VORTS ROTATING ABOUT. 00Z UKMET/CANADIAN GLOBAL SHOW ONE SHORTWAVE TROUGH MOVING THROUGH BY 00Z SUNDAY...WHILE NAM/GFS ARE GOOD 6+ HOURS SLOWER. THOSE MODELS ARE IN BETTER AGREEMENT WITH AMPLIFYING UPPER WAVE DIVING SOUTH FROM THE NORTHWEST TERRITORIES...LEADING TO POTENTIAL CLOSED LOW AT 500 MB MOVING THROUGH LOWER MICHIGAN ON SUNDAY. AS FAR AS TEMPS GO FOR THE WEEKEND...GFS MOS MAXES ON SATURDAY LOOK A LITTLE TOO WARM WITH WEAK LOW LEVEL COLD ADVECTION DURING THE DAY AND 925 MB TEMPS FORECASTED TO DROP BELOW -3 C BY 12Z SATURDAY (BLENDING GFS/NAM). WITH CLOUDS AND SNOW SHOWERS SATURDAY NIGHT...WOULD EXPECT MINS TO HOLD IN THE TEENS TO AROUND 20. GFS MOS GUIDANCE TEMP LOOK GOOD FOR SUNDAY...UPPER TEENS TO LOWER 20S...A COUPLE DEGREES WARMER THAN YESTERDAY`S AIRMASS. YESTERDAY`S DTX SOUNDING CAME IN WITH -20 C AT 850MB...WHILE A BLEND OF THE UKMET/GFS/NAM PUTS THE 850 MB TEMP AT -18 C BY 00Z MONDAY. BROAD CYCLONIC FLOW AND LINGERING MOISTURE UP TO 700 MB STILL SUPPORTS A LOW CHANCE OF SNOW SHOWERS SUNDAY NIGHT BEFORE SHORTWAVE RIDGING MOVES THROUGH THE CENTRAL GREAT LAKES ON MONDAY. WITH THE LINGERING CLOUDS AND GRADIENT SUNDAY NIGHT...WITH LEAVE THE MINS IN THE SINGLE DIGITS. 00Z EUROPEAN/GFS/CANADIAN GLOBAL ALL SHOWING AN UPPER WAVE/TROUGH SWINGING THROUGH MONDAY NIGHT/TUESDAY...WORTHY OF A CHANCE OF LIGHT SNOW AS A SURFACE REFLECTION IS ALSO FORECASTED TO MOVE THROUGH. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...WINTER WEATHER ADVISORY...MIZ047-MIZ048-MIZ049-MIZ053-MIZ054- MIZ055-MIZ060-MIZ061-MIZ062-MIZ063-MIZ068-MIZ069-MIZ070- MIZ075-MIZ076 UNTIL 7 PM FRIDAY. LAKE HURON...SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...3 PM FRIDAY TO MIDNIGHT SATURDAY. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......BGM SHORT TERM...BGM LONG TERM....SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 450 AM EST FRI JAN 26 2007 .DISCUSSION... THERE ARE TWO BIG FCST CONCERNS EARLY THIS MORNING. FIRST IS LAKE ENHANCEMENT POTENTIAL IN SRLY FLOW OFF LAKE MICHIGAN. SECOND CONCERN REVOLVES AROUND UPCOMING HEADLINE LAKE EFFECT EVENT SAT/SUN. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A DEEP VORTEX DESCENDING OVER NEW ENGLAND. NW FLOW AROUND THE WRN SIDE OF THIS VORTEX IS DOMINATING THE GREAT LAKES REGION EARLY THIS MORNING. MEANWHILE... UPSTREAM A FAIRLY IMPRESSIVE LOOKING SHORTWAVE IS HEADING SE THRU SASKATCHEWAN. 00Z SOUNDING FROM CWEG IN ALBERTA SHOWED A RESPECTABLE 12HR 500MB HEIGHT FALL OF 140M WITH THIS SYSTEM. AHEAD OF THE SHORTWAVE...POOL OF VERY WARM AIR DUE MOSTLY TO DOWNSLOPING OFF THE ROCKIES HAS PUSHED OUT OVER THE NRN PLAINS. 00Z RAOBS SHOWED 850MB TEMPS ALL THE WAY UP TO 11C AT KBIS AND 14C AT KUNR. THIS WAA HAS LED TO A BAND OF MID CLOUDS ACROSS THE UPPER MIDWEST/WRN GREAT LAKES REGION...AND SATELLITE AND REGIONAL RADAR IMAGERY SHOW CONVECTIVE ELEMENTS IN THE CLOUD BAND. 00Z KINL SOUNDING DID SHOW DRY-ADIABATIC LAPSE RATE BTWN 650 AND 550MB. SO FAR...ONLY SPOTTY -SN/FLURRIES HAVE BEEN NOTED. LACK OF PCPN IS DUE TO DRY AIRMASS PER 00Z KINL/KGRB SOUNDINGS. DRY AIR IS NOT TOO SUBSTANTIAL THOUGH AND WOULD EXPECT PCPN COVERAGE TO GRADUALLY INCREASE WITH TIME. MODELS ARE IN GOOD AGREEMENT TAKING SHORTWAVE OVER SASKATCHEWAN TO JUST NW OF LAKE SUPERIOR BY 00Z SAT. ON THIS TRACK...IMPRESSIVE DEEP LAYER FORCING INDICATED BY NAM/GFS 850/500MB QVECTOR CONVERGENCE WILL PASS JUST NE OF UPPER MI THIS EVENING. EVEN SO...NW-SE ORIENTED MODEST DEEP LAYER FORCING WILL CONTINUE ALL DAY ACROSS MOST OF THE FCST AREA. AS THE SHORTWAVE APPROACHES...BROAD/ELONGATED SFC LOW PRES CURRENTLY OVER MANITOBA WILL SLIDE ESE TO CNTRL UPPER MI/NW LAKE SUPERIOR. GIVEN FORCING AND LOCATION OF STRENGTHENING LOW-LEVEL CONVERGENCE ACROSS CNTRL UPPER MI ALONG SFC TROF/WARM FRONT EXTENDING SE FROM APPROACHING LOW PRES...EXPECT MORE PERSISTENT -SN TO TAKE SHAPE OVER ROUGHLY THE E HALF OF FCST AREA TODAY. STRONG ISENTROPIC ASCENT (290K SFC OR ROUGHLY 700-750MB) IS SET FOR THE MORNING HRS THOUGH...SO HEAVIER SNOW SHOULD OCCUR THIS MORNING. THIS BRINGS UP THE PROSPECT FOR LAKE ENHANCEMENT OVER THE SE FCST AREA AS 850MB TEMPS WILL STILL BE ON THE ORDER OF -9 TO -12C OVER NRN LAKE MICHIGAN THIS MORNING AT THE TIME OF BEST FORCING. AT FIRST GLANCE...THERE WOULD APPEAR TO BE SOME CONCERN THAT THE STRONG WAA WOULD CUT OFF LAKE ENHANCEMENT POTENTIAL (00Z KMPX SOUNDING SHOWED 850MB TEMP OF ONLY -2C). HOWEVER...COOLING THRU UPWARD MOTION IN INTIAL DRY AIRMASS AND EVAPORATIVE COOLING SHOULD TEND TO SLOW THE ACTUAL WARMING AS MODELS INDICATE. AT THE LOW-LEVELS SRLY FLOW BECOMES CONVERGENT INTO SCHOOLCRAFT COUNTY AS SFC TROF DEVELOPS TOWARD NRN LAKE MICHIGAN. HAVE THUS OPTED TO ISSUE A SNOW ADVY (2-4 INCHES) FOR SRN SCHOOLCRAFT COUNTY WHERE BEST FETCH ACROSS THE LAKE TAKES AIM. CONSIDERED DELTA COUNTY...BUT WITH SHARP CONVERGENCE TO SET UP JUST E OF THERE...EXPECT LIGHTER SNOW ACCUMULATIONS. NONETHELESS...WILL NEED TO KEEP AN EYE ON THE FAR ERN PART OF DELTA COUNTY IN CASE SRLY FLOW BACKS MORE THAN EXPECTED BEFORE BEST FORCING DEPARTS. WILL BUFFER THE ADVY AREA WITH ROUGHLY 1-3 INCHES OF SNOW FROM ERN DELTA INTO ALGER/LUCE. GIVEN THE CONVECTIVE LOOK TO CLOUDS UPSTREAM...WILL NEED TO WATCH FOR SOME BURSTS OF HEAVIER SNOW AS STEEP MIDLEVEL LAPSE RATES SPREAD OVER THE AREA THIS MORNING. AFTER SOME MORNING -SN/FLURRIES WEST...POTENTIAL FOR FZDZ DEVELOPS AS MIDLEVEL MOISTURE EXITS LEAVING MOIST LAYER EXTENDING TO NEAR THE -10C ISOTHERM. SW HALF OF FCST AREA APPEARS MOST AT THREAT FOR SPOTTY -FZDZ WITH WARMER MOIST LAYER TEMPS...AND WILL INCLUDE MENTION THERE. SHORTWAVE TRACKS ACROSS LAKE SUPERIOR TONIGHT...KEEPING BEST FORCING TO THE NE OF HERE. IN FACT...MODELS ACTUALLY SHOW STRONG SUBSIDENCE OVER MUCH OF THE FCST AREA FOR A GOOD PORTION OF TONIGHT. SO...AFTER SOME EVENING -SN OVER THE FAR E...THERE MAY NOT BE MUCH IF ANY PCPN AGAIN UNTIL LATE. THIS BRING US TO THE UPCOMING LAKE EFFECT EVENT. BROAD SFC LOW PRES OVER CNTRL UPPER MI/NW LAKE SUPERIOR THIS EVENING WILL SHIFT TO LAKE HURON/ERN LAKE SUPERIOR BY 12Z SAT. ANOTHER SHORTWAVE DROPPING SE WILL THEN SEND SFC LOW/TROF S ACROSS UPPER MI SAT. THE EXACT DETAILS OF HOW THIS WILL PLAY OUT IS UNCERTAIN. GFS INDICATES SHARP SFC TROF REACHING THE KEWEENAW AROUND 12Z...THEN CLEARING NRN UPPER MI BY 18Z SAT. NAM IS ABOUT 6HRS SLOWER. RUC13 AND REGIONAL CANADIAN MODEL ARE NEARLY IDENTICAL IN SHOWING EVEN SHARPER SFC TROFFING AND HINT AT MESOLOW OVER CNTRL LAKE SUPERIOR AT 12Z N OF STANNARD ROCK. MESOLOW THEN DROPS TO NEAR MUNISING BY 18Z. SO...TIMING IS ESSENTIALLY BTWN THE GFS AND NAM. SINCE THE REGIONAL CANADIAN OFTEN DID A MUCH BETTER JOB HANDLING WIND FIELDS OVER THE LAKE IN PAST EVENTS THIS SEASON WHEN THERE WERE SHARP CONVERGENCE ZONES OVER LAKE SUPERIOR (SEVERAL IN EARLY DEC)...WILL FAVOR ITS SOLUTION WITH REGARD TO DETAILS OF WIND FIELDS. OF COURSE...PAST PERFORMANCE IS NO GUARANTEE OF FUTURE PERFORMANCE...BUT IT DOES HAVE STRONG SUPPORT FROM THE RUC13. THIS SOLUTION RESULTS IN NW FLOW INTO WRN UPPER MI OVERNIGHT AS CAA GETS UNDERWAY...BUT IT WILL PROBABLY BE AFTER 12Z BEFORE LAKE ENHANCEMENT BEGINS IN ASSOCIATION WITH NEXT APPROACHING SHORTWAVE. WILL BRING IN -SHSN OVER THE W AND N OVERNIGHT AS 850MB TEMPS DROP TO -14C OR SO BY 12Z. AS MESOLOW/SFC TROF DROP S INTO NRN UPPER MI DURING THE LATE MORNING INTO AFTN...EXPECT WIND SHIFT TO BE ACCOMPANIED BY A BAND OF HVY SNOW AS FCST SOUNDINGS INDICATING DEEP MOISTURE TO 10KFT OR MORE AND NO INVERSION. SNOW COULD BE QUITE INTENSE OVER NCNTRL UPPER MI IF MESOLOW DOES FORM ON SFC TROF. IN THE WAKE OF WIND SHIFT... CONDITIONS LOOK FAVORABLE FOR MDT/HVY LAKE ENHANCED SNOW TRANSITIONING TO PURE LES FOR N WIND FAVORED SNOWBELTS SAT AFTN THRU SAT NIGHT BEFORE SHARP DRYING AND CRASHING OF INVERSION TO 4-5KFT OCCURS EARLY SUN. WILL LEAVE GOING WATCHES AS IS (GOGEBIC/ONTONAGON/MARQUETTE/ALGER) GIVEN UNCERTAINTY ON INITIAL WIND FIELDS AND ON START TIME OF HVY SNOW...BUT IT DOES LOOK LIKE WATCHES WILL BE ABLE TO TRANSITION TO WARNINGS BASED ON VERY FAVORABLE LOOK OF FCST SOUNDINGS. ONE CHANGE WILL BE TO ADD BARAGA COUNTY TO WATCH AS N WIND DURING LAKE ENHANCEMENT PERIOD WILL FAVOR THAT AREA FOR HVY SNOW AS WELL. HOUGHTON/KEWEENAW/LUCE WILL LIKELY NEED ADVYS FOR THIS EVENT. ADVY TYPE SNOW MAY ALSO SPREAD AS FAR S AS DELTA COUNTY SAT NIGHT UNDER NRLY FLOW. && .MQT WATCHES/WARNINGS/ADVISORIES... SNOW ADVY TODAY MIZ014. LAKE EFFECT SNOW WATCH LATE TONIGHT THRU SUN MORNING MIZ002-009. LAKE EFFECT SNOW WATCH SAT MORNING THRU SUN MORNING MIZ004. LAKE EFFECT SNOW WATCH SAT MORNING THRU SUN AFTN MIZ005-006. && $$ ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1015 PM EST THU JAN 25 2007 .UPDATE... KMQT RADAR INDICATED INITIAL BAND OF MID/HIGH CLOUDS ALONG WITH A FEW FLURRIES MOVING THROUGH W UPR MI. UPSTREAM...ADDITIONAL RETURNS WERE DEVELOPING OVER NW MN. THE 00Z NAM AND 18Z GFS WERE IN GOOD AGREEMENT IN DEPICTING A TIGHT BAND OF MODERATE TO STRONG 280K-290K ASCENT FROM W INTO CNTRL UPR MI BY 12Z. THE NAM HAS TRENDED TOWARD THE GFS WITH GREATER LOW LVL SATURATION WITHOUT AS MUCH LAG BEHIND THE MID LVL MOISTURE. HOWEVER...GIVEN THE VERY DRY ANTECEDENT AIRMASS...PER 00 KSAW TAMDAR SNDGS...WILL KEEP ONLY CHANCE POPS THROUGH THE OVERNIGHT. OVER THE WEST...ENOUGH MOISTURE FCST NEAR THE -10C ISOTHERM...PER NAM SNDGS...FOR MAINLY SNOW CHANCES RATHER THAN FREEZING DRIZZLE. && .PREV DISCUSSION...ISSUED 313 PM EST THU JAN 25 2007 SHORT TERMTONIGHT)... 12Z RAOBS/WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE TROF IN ERN NAMERICA DOWNSTREAM OF RDG OVER THE ROCKIES. LES OVER THE FA DOWNWIND OF LK SUP IN COLD NW FLOW BTWN ARCTIC HI PRES OVER ONTARIO AND LO PRES IN THE LOWER GREAT LKS IS ON THE DIMINISHING TREND AS VERY DRY/STABLE AIR SHOWN ON UPSTREAM 12Z RAOBS/TAMDAR SDNG FM CYQT (INVRN BASE H925-95 AND PWAT AS LO AS 0.05 INCH) MOVES OVER THE UPR LKS UNDER BLDG H5 HGTS/ INCRSG LARGER SCALE ACYC FLOW DESPITE SOME LINGERING CNVGC ALG LK INDUCED TROFFING EXTENDING FM LO TO THE SE NW ACRS LK HURON INTO ALGER COUNTY/CNTRL LK SUP. UPSTREAM...A SHRTWV MOVING INTO NRN ALBERTA/SASKATCHEWAN IS TOPPING THE ROCKIES RDG. QUITE A BIT OF MID CLD AND EVEN SOME PTCHY -SN NOTED FM SCNTRL CAN INTO NE ND/NW MN IN THE SW FLOW/WAD PATTERN BTWN LO PRES ASSOCIATED WITH THIS SHRTWV AND THE HI PRES SYS OVER ONTARIO AND THE UPR MS RIVER VALLEY. PWAT 0.44 INCH AT YQD...SO THERE IS MORE MSTR AVBL TO THIS SHRTWV. MAIN FCST CONCERNS IN THE SHORT TERM ARE LINGERING LES TRENDS AND -SN CHCS ASSOCIATED WITH SHRTWV NOW TOPPING ROCKIES RDG. FOR TNGT...GUIDANCE SHOWS RISING HGTS OVER THE UPR GRT LKS IN ADVANCE OF SHRTWV NOW OVER NRN ALBERTA/SASKATCHEWAN...WHICH IS FCST TO REACH NR LK WINNIPEG BY 12Z FRI. AS HGTS RISE AND SFC RDG AXIS/ LOWER INVRN BASE/DEEPER DRY AIR PASSES ACRS THE CWA THIS EVNG UNDER THE RISING HGTS...EXPECT LES TO DIMINISH AND THEN END WITH LTL ADDITIONAL ACCUMULATION. WL LET ANY GOING HEADLINES EXPIRE AS SCHEDULED. ALTHOUGH SKIES WL BE PCLDY FOR A TIME WITH ARRIVAL OF RDG AXIS (EXCEPT OVER THE KEWEENAW WITH BKN-OVC SC LINGERING IN W-SW FLOW EVEN ON BACK SIDE OF RDG)...NAM/GFS SHOW ISENTROPIC LIFT ON THE 280-290K SFCS OVERSPREADING THE FA QUICKLY AS SW RETURN FLOW DVLPS IN THE WAKE OF DEPARTING SFC RDG. GFS IS MOST AGGRESSIVE AT PUSHING HIER MID LVL MSTR TO THE E...AND USED ITS 280K SFC RH AOA 70 PCT TO TIME ARRIVAL OF MID CLD AS THIS PROG APPEARS TO CORRELATE WELL WITH OBSVD HI SC/LO AC CLD UPSTREAM. NAM FCSTS LLVLS BLO THE MID CLD DECK REMAINING SO DRY THAT MODEL QPF IS ZERO...BUT GFS GENERATES SOME LGT PCPN UNDER THE STRONGER ISENTROPIC LIFT AFT ABOUT 03Z OR SO OVER THE W AND ACRS THE ENTIRE CWA AFT 06Z WITH ARRIVAL OF UPR DVGC IN RRQ OF H3 JET MAX FCST TO MOVE OVER SE ONTARIO BY 12Z FRI. GFS FCST SDNGS ARE QUITE A BIT MORE MOIST THRU MOST OF THE TROP IN LINE WITH OBSVD 12Z YQD SDNG...BUT MODEL FCST SDNGS DO SHOW LINGERING DRY LYR BTWN H75-55...WHICH WOULD ALSO BE THE PRIME DENDRITIC SN GROWTH LYR. CONSIDERING THIS DRY LYR AS WELL AS ANTECEDENT DRY AIR...LIMITED COVG OF OBSVD SN UPSTREAM...AND NAM FCST...HAVE OPTED TO RETAIN POPS BUT CUT VALUES FM HI CHC TO LWR CHC IN LINE WITH GFS MOS GUIDANCE. AS FOR TEMPS...EXPECT MIN TEMPS RELATIVELY EARLY BEFORE THICKER MID CLD/A BIT STRONGER SW FLOW DVLPS W-E AFT EARLY THIS EVNG. KC .LONG TERM (FRIDAY THROUGH THURSDAY)... THE MAIN FORECAST CONCERN FOR THIS PORTION OF THE FORECAST REMAINS THE LAKE EFFECT SNOW EVENT FOR LATE FRIDAY NIGHT THROUGH MUCH OF THE WEEKEND. ONCE AGAIN FOR THIS PERIOD...AM GENERALLY DISCOUNTING THE NAM...AS IT IS OUT OF BOUNDS WHEN COMPARED TO THE GLOBAL MODELS. AS A RESULT...HAVE LEANED THIS FORECAST CLOSER TO THE GFS SOLUTION. GFS OFF OF BUFKIT IS PUTTING OUT OVER HALF AN INCH OF QFP OVER IWD DURING THE NEXT 5 DAYS. CONTINUE TO MONITOR THE TRACK OF THE SURFACE LOW...CURRENTLY CENTERED OVER THE SOUTHERN NORTHWEST TERRITORIES SLIDING INTO NORTHERN SASKATCHEWAN. THIS LOW WILL SLIDE SOUTHEASTWARD...AND OVER THE WESTERN HALF OF LAKE SUPERIOR BY FRIDAY AFTERNOON AND THEN SOUTHEASTWARD OVER LAKE HURON BY 12Z SATURDAY. THIS WILL FIRST ALLOW FOR A LONG SOUTHERLY FETCH ACROSS LAKE MICHIGAN LATE FRIDAY MORNING THROUGH EARLY AFTERNOON (GENERALLY 2 TO 4 INCHES OF SNOW EXPECTED ACROSS THIS AREA FRIDAY)...AND THEN SWING THE WINDS OUT OF A GENERALLY NORTH TO NORTHWESTERLY DIRECTION FRIDAY NIGHT (AND KEEP THEM BETWEEN 300 AND 030 THROUGH TUESDAY). 850MB TEMPERATURES...AFTER WARMING TO -7C OR SO FRIDAY WILL COOL DOWN TO -12C ACROSS THE AREA BY 12Z SATURDAY...ALLOWING FOR A BETTER CHANCE OF LAKE EFFECT OR LAKE ENHANCED SNOW. 850MB TEMPERATURES WILL THEN SLOWLY COOL TO -20 TO -22C BY 06Z SUNDAY. GIVEN THIS...HAVE HOISTED LAKE EFFECT SNOW WATCHES FOR GOGEBIC...ONTONAGON...MARQUETTE...AND ALGER COUNTIES FOR SATURDAY MORNING THROUGH MID DAY SUNDAY. FOR FRIDAY NIGHT HAVE ADJUSTED TEMPS DOWN A COUPLE OF DEGREES ACROSS OUR CLIMATOLOGICALLY COOLER SOUTH CENTRAL CWA...WITH THE IDEA THAT THE DRY SLOT MAY COME IN EARLY AND ALLOW TEMPS TO DROP. FIRST COLD FRONT IS EXPECTED TO CROSS THE CWA LATE FRIDAY AFTERNOON THROUGH 06Z SATURDAY. COOLER TEMPS ALOFT WILL TAKE A BIT LONGER TO SLIDE IN. EXPECT THE SINGLE DIGITS TO LOW TEENS FOR HIGH TEMPERATURES SUNDAY...AS THE COLDEST AIR SINKS OVERHEAD. WINDS BACK SLIGHTLY SUNDAY...ADDING TO THE CONVERGENCE OVER THE EASTERN THIRD OF THE LAKE SUPERIOR SHORELINE FROM MUNISING EAST. AS HAS BEEN THE TREND OVER THE LAST COUPLE OF SHIFTS...HAVE INCREASED POPS HERE TO DEFINITE. AS FOR RIGHT NOW...DO NOT HAVE ANY WATCHES/WARNINGS OR ADVISORIES POSTED FOR THE EASTERN PORTIONS OF THE CWA (EXCEPT ALGER COUNTY)...BUT AS THE TIME NEARS HEADLINES WILL LIKELY BE NEEDED. MONDAY THROUGH THURSDAY (DAYS 4-7)...WITH THE RELATIVE CONSISTENCY IN THE EXTENDED RANGE...WITH LESS MODEL FLIP FLOPPING THAN USUAL...FEW CHANGES WERE MADE...PARTICULARLY TO TEMPERATURES. STILL...DID COOL DOWN TEMPERATURES ROUGHLY 4 DEGREES ACROSS THE BOARD MONDAY AFTERNOON. SO THE OVERALL PATTERN INCLUDES A SERIES OF SHORTWAVES IN THE POLAR/ARCTIC JET CONTINUALLY RE-ENFORCING OUR ALREADY COLD AIRMASS. MONDAY 12Z...LOOKING AT THE MID LEVELS...THE GFS AND ECMWF BEGIN TO BECOME A LITTLE MORE NOTICEABLE IN THERE DIFFERENCES. THE 500MB DEPICTED BY THE GFS...ALTHOUGH SIMILAR IN STRENGTH IS ABLE TO SLIDE FURTHER SOUTHWARD...MAKING IT INTO EASTERN LAKE HURON BY THIS TIME...WHILE THE ECMWF HAS IT REMAINING OVER EASTERN HUDSON BAY. AS PREVIOUSLY STATED...GENERALLY DISREGARDED THIS DISCREPANCY...AND SIDED CLOSER TO THE GFS SOLUTION. UPDATED AND INCREASED CLOUD COVER FOR MONDAY INTO MONDAY NIGHT...AS SHORTWAVE SLIDES IN FROM THE NORTHWEST...ACCORDING TO THE 06Z GFS. ALTHOUGH IT SEEMS THAT THE SHORTWAVE HAS DROPPED FURTHER SOUTH FOR THE 12Z GFS RUN...STILL BELIEVE THAT WE WILL HAVE MORE THAN 40 PERCENT CLOUD COVER FOR THIS PERIOD...SO HAVE KEPT THE ADJUSTED MORE PESSIMISTIC CLOUD FOR MONDAY INTO MONDAY NIGHT. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR MIZ005-006. LAKE EFFECT SNOW WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING FOR MIZ002-009. && $$ .UPDATE...JLB .SHORT TERM...KC .LONG TERM...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1006 PM EST THU JAN 25 2007 .UPDATE...LAKE STRATOCU GRADUALLY SPREADING INLAND FROM LAKE MI AS 1000-850MB WINDS BACK WESTERLY. A FEW FLURRIES ARE BEING CARRIED INTO PARTS OF NW LOWER MI...WHERE THE FETCH IS LONGEST. STILL ENOUGH OF A NORTHERLY COMPONENT TO ALLOW SNOW SHOWERS TO GRAZE BY WHITEFISH PT IN EASTERN UPPER MI...THOUGH EXPECT THAT TO COME TO END AS BACKING CONTINUES. THE INCOMING CLOUDS HAVE STALLED THE TEMPERATURE FREE-FALL IN EASTERN UPPER...AND NW AND N CENTRAL LOWER MI. PARTS OF NE LOWER MI ARE STILL TUMBLING THOUGH...WITH OSCODA BRIEFLY DOWN TO -11F. BRRRR. TEMPS/SNOW TRENDS ARE THE MAIN CONCERN. LOW CLOUDS SHOULD CONTINUE TO SLOWLY EXPAND INTO NE LOWER MI. ELSEWHERE...MID CLOUDS ARE ARRIVING FROM THE NW OVER TOP OF THE STRATOCU...SO CONDITIONS WILL REMAIN MAINLY CLOUDY. TEMPS WILL THUS BE STEADY TO SLOWLY RISING...AS IS CURRENTLY PORTRAYED IN THE GRIDDED FORECASTS. WILL MAKE A FEW TWEAKS...BUT EARLIER UPDATE APPEARS TO BE HOLDING UP FAIRLY WELL (OUTSIDE OF OSCODA). AS 1000-850MB WINDS GRADUALLY BACK WSW...RISK FOR LAKE EFFECT SNOW/FLURRIES WILL END IN NW CHIPPEWA...AND SHIFT NORTHWARD IN NORTHERN LOWER TOWARD EMMET CO...THE STRAITS...AND MACKINAC CO. LATE TONIGHT...A MORE EMPHATIC BAND OF MID LEVEL MOISTURE AND INSTABILITY (PER BUMPY-LOOKING CLOUDS IN NORTHERN MN) WILL ARRIVE FROM THE NW. EVEN WITH SHARP WARM ADVECTION...THERE IS ENOUGH INSTABILITY LEFT TO KICK LAKE EFFECT PRECIP UP A COUPLE OF NOTCHES. EXPECT NOTHING MORE THAN ONGOING FLURRIES FOR MOST OF THE NIGHT...BUT AFTER 4/5AM MORE SUBSTANTIAL SNOW SHOWERS ARE LIKELY. IN FACT...MODEL SOUNDINGS ARE KIND OF OMINOUS BY 12Z...WITH DELTA T/S IN THE LOW/MID TEENS AND A DEEP ISOTHERMAL LAYER AT -10C FROM THE SURFACE TO 650MB/12K FEET. HOWEVER...THE BEST MID LEVEL MOISTURE STILL STAYS WEST OF I-75 THRU 12Z...NOT IMPACTING THE LONGEST LAKE MI FETCH INTO THE STRAITS. SO INSTEAD...WILL BOOST POPS TO LIKELY ONLY ALONG THE LEELANAU COUNTY SHORE OF LAKE MI...WHERE A QUICK INCH OF SNOW IS POSSIBLE VERY LATE TONIGHT. && .PREV DISCUSSION ISSUED 732 PM THU JAN 25... UPDATE...WILL LOWER MIN TEMPS AT LEAST A LITTLE IN MUCH OF THE FORECAST AREA. LAKE CLOUDS ARE SLOWLY ADVECTING EASTWARD AS LOW LEVEL WINDS BACK...AND A BAND OF MID CLOUDS WERE FURTHER UPSTREAM IN WESTERN UPPER MI AND WI. THE INCREASING CLOUDS WILL KEEP THINGS FROM GETTING RIDICULOUS. HOWEVER...A FEW SITES ARE ALREADY BELOW FORECAST MINS (OSCODA AT -4F BEING THE MOST DRASTIC EXAMPLE). ZOLTOWSKI DISCUSSION...20Z SATELLITE/SURFACE/AND RUC ANALYSIS SHOWS SURFACE RIDGE AXIS OVER THE WESTERN LAKES REGION SLOWLY BUILDING EAST INTO THE AREA. AT THE MID LEVELS...EASTERN CONUS LONG WAVE TROUGH BEGINNING TO GET BOOTED EAST AS POTENT SHORTWAVE OVER CENTRAL ALBERTA BEGINNING TO MAKE THE TURN SOUTHEAST ON DOWNSTREAM SIDE OF AMPLIFIED INTERMOUNTAIN RIDGE. NORTH FLOW LAKE EFFECT SNOWS...ALBEIT RATHER WEAK AND DISORGANIZED...STARTING TO TRANSITION TO MORE NORTHWESTERLY AS SURFACE RIDGE MOVES IN. CLASSIC VISIBLE SATELLITE SHOT THIS AFTERNOON SHOWING LAKE CLOUD STREAMERS IMPINGING ON THE IMMEDIATE SHORELINES OF THE LAKES WITH MOST INLAND AREAS CLOUD FREE. DESPITE THE SUN...TEMPERATURES HAVE BEEN SLOW TO RECOVER WITH CONTINUING COLD AIR ADVECTION THROUGH THE DAY AND HIGH ALBEDO WITH FRESH SNOW COVER. FORECAST CONCERNS INITIALLY CENTER ON LAKE SNOW CHANCES AND TEMPERATURES THIS EVENING WITH FOCUS THEN SHIFTING TO RAPIDLY APPROACHING AFOREMENTIONED ALBERTA SHORTWAVE. TONIGHT...DESPITE EXTREME OVER WATER INSTABILITY THIS EVENING WITH 850MB TEMPERATURES AROUND -20C (WITH CORRESPONDING DELTA T VALUES IN THE LOWER 20S CELSIUS)...OTHER FACTORS NOT SUPPORTIVE OF SIGNIFICANT LES THIS EVENING WITH ANTICYCLONIC FLOW...INVERSION HEIGHTS AT ABOUT 3.5KFT AND 850MB-700MB MOISTURE <40 PERCENT. AS WINDS CONTINUE TO BACK AROUND NORTHWESTERLY EXPECT SNOW SHOWERS TO SPREAD A LITTLE FARTHER INLAND THIS EVENING AND WILL CONTINUE SCATTERED WORDING. GIVEN ABOVE PARAMETERS NOT EXPECTING MUCH MORE THAN A COUPLE TENTHS OF AN INCH OF NEW ACCUMULATION. THEREFORE...WILL LET LAKE SNOW ADVISORIES AND WARNINGS EXPIRE AT 4 PM. AWAY FROM THE LAKE...EVENING CLEAR TO PARTLY CLOUDY SKIES WILL ALLOW TEMPERATURES TO QUICKLY DROP OFF...REACHING THE MID SINGLE DIGITS BELOW ZERO. OTHERWISE...SOME MODERATION FROM THE LAKES WILL KEEP LOWS THIS EVENING IN THE SINGLE DIGITS TO LOW TEENS. BY LATER TONIGHT...280K-290K ISENTROPIC ASCENT RAMPS UP WELL OUT AHEAD OF DEVELOPING CENTRAL PLAINS WARM FRONT. MODEL DISCREPANCIES CONTINUE WITH REGARDS TO MID LEVEL MOISTURE WITH 12Z GFS/UKMET/AND ECMWF STILL MUCH MORE AGGRESSIVE THAN NAM-WRF. GIVEN CONSISTENTLY WITH REGARDS TO FORMER SOLUTIONS AND LATEST ANALYSIS SUPPORTING MORE MOIST SCENARIO...WILL SIDE WITH THESE SOLUTIONS. THUS...WILL KEEP CHANCE POPS AFTER MIDNIGHT. ALTHOUGH RAPID WAA HELPS BOOST 850MB TEMPERATURE TO A COUPLE DEGREES EITHER SIDE OF -10C...ENOUGH INSTABILITY REMAINS FOR SOME SOUTHWEST FLOW LAKE ENHANCEMENT LATE TONIGHT AS WINDS CONTINUE TO BACK AROUND. HOWEVER...RAPIDLY BACKING WINDS BY MORNING MAY PREVENT ANY SIGNIFICANT LAKE CONTRIBUTION. GIVEN SHORT WINDOW OF EVENT DID NOT INCLUDE IN FORECAST AT THIS TIME. WILL PASS CONCERNS ALONG TO EVENING CREW. AFTER QUICK FALL OFF THIS EVENING...TEMPERATURES WILL STABILIZE AND START TO WARM SOME LATER TONIGHT WITH ONSET OF INCREASING CLOUD COVER AND SOUTHWEST RETURN FLOW AS RIDGE AXIS PASSES OFF TO THE EAST.. FRIDAY...SIDING WITH THE MORE MOIST SOLUTIONS...HAVE MAINTAINED LIKELY LIGHT SNOW WORDING DURING THE MORNING AS ISENTROPIC UPGLIDE IN CONJUNCTION WITH 850MB-650MB FRONTOGENETICAL FORCING SWINGS THROUGH. SPEED AND LIMITED MOISTURE (MIXING RATIOS ONLY ON THE ORDER OF 2 G/KG WITH PWAT VALUES OF AROUND 0.40 INCHES) SHOULD KEEP ACCUMULATIONS ON THE ORDER OF 1 TO 3 INCHES. GROWING CONCERN FOR SOME FREEZING DRIZZLE FOR THE AFTERNOON AS MODEL POINT SOUNDINGS SHOW MID LEVEL MOISTURE RAPIDLY STRIPPING AWAY ABOVE SATURATED LOW LEVELS...WHICH REMAINS BELOW -10C. GIVEN SOME CONSISTENCY IN THIS REGARDS DID BRING IN CHANCE OF FREEZING DRIZZLE IN COMBINATION WITH THE LIGHT SNOW DURING THE AFTERNOON. TEMPERATURES WILL BE SEVERAL DEGREES WARMER THAN TODAYS READINGS...REACHING HIGHS IN THE MID 20S TO NEAR 30. MARINE...EXTENDED SCA FOR LAKE HURON NEARSHORE WATERS BORDERING NORTHERN LOWER MICHIGAN THROUGH 04Z TO ACCOUNT FOR LINGERING WIND GUSTS AND SOME CONVERGENCE WITH FAVORED NORTHWEST FLOW. MSB LATER PERIODS...MEDIUM RANGE MODELS/ENSEMBLES CONTINUE TO BE IN VERY GOOD AGREEMENT WITH THE UPCOMING COLD PATTERN. MAIN FORECAST CONCERNS THROUGH NEXT WEEK WILL CONTINUE TO REVOLVE AROUND A SERIES OF NORTHERN STREAM SYSTEMS THAT WILL DROP SOUTHEAST TOWARDS THE GREAT LAKES...EACH SEPARATED BY COUPLE DAYS OR SO. MODELS INDICATE A STRONG RIDGE DEVELOPING BY EARLY NEXT WEEK...WITH THE FLOW ACROSS THE GREAT LAKES ORIGINATING OUT OF THE ARCTIC. IN THE SHORT TERM...HOWEVER...GFS AND THE EUROPEAN MODELS HAVE BEEN SHOWING DECENT CONTINUITY OVER THE LAST DAY OR SO...UNLIKE THE NAM WHICH SEEMS TO BE TRYING TO CATCH UP WITH THE PREVIOUSLY MENTIONED MODELS. THEREFORE...THIS FORECAST CONSISTS OF A BLEND BETWEEN THE GFS/ECMWF/UKMET MODELS. FRIDAY NIGHT INTO SATURDAY...GFS ENSEMBLE/GFS/UKMET/ECMWF AGREE WELL WITH THE TRACK OF THE CLIPPER SYSTEM AND TRACK OF ITS ASSOCIATED SURFACE LOW ACROSS THE STRAITS. THIS SURFACE LOW AND LEADING COLD FRONT WILL PASS ACROSS NORTHERN MICHIGAN FRIDAY NIGHT. MOISTURE DEPTH IS A CONCERN DURING THE EVENING HOURS...ESPECIALLY ACROSS NORTHERN LOWER WHERE THE MOISTURE STRUGGLES TO REACH -10C. THIS IS NOT SO MUCH OF A PROBLEM ACROSS EASTERN UPPER...CLOSER TO THE SHORTWAVE. WILL THEREFORE HAVE TO MENTION A CHANCE OF FREEZING DRIZZLE ACROSS NORTHERN LOWER DURING THE EVENING BEFORE COLD ADVECTION AND DEEPER MOISTURE ARRIVES OVERNIGHT. 1000-850MB WINDS SHIFT TO WNW BEHIND THE COLD FRONT...BRINGING LAKES MICHIGAN AND SUPERIOR BACK INTO PLAY (ALBEIT MARGINALLY) AS 850MB TEMPERATURES COOL TO AROUND BY -10C TO -12C BY 12Z AND -12C TO -16C BY 18Z. WITH THE STRONGEST FORCING AND COLDER THERMODYNAMIC PROFILE LYING ACROSS EASTERN UPPER...HAVE DECIDED TO UP POPS TO LIKELY ACROSS WESTERN CHIPPEWA COUNTY. SHORTWAVE AND SECONDARY COLD FRONT THEN SWINGS SOUTH AND CLEARS ALL BUT THE SOUTHERN FRINGES OF THE CWA BY 00Z SATURDAY. 1000-850MB WINDS THEN SHIFT TO NNW BEHIND THIS SECOND FRONT BRINGING IN MUCH COLDER AIR ONCE AGAIN. HAVE THROWN UP A LIKELY POP OVER PORTIONS OF NW LOWER MICHIGAN WHERE THE COMBINATION OF WNW AND NNW FLOW SEEM TO CONVERGE TO PRODUCE THE BEST CHANCE OF PRECIP. SATURDAY NIGHT INTO SUNDAY... SHORTWAVE AND SECONDARY COLD FRONT MOVE SOUTH AND CLEAR THE CWA DURING THE EVENING HOURS. STRONG COLD ADVECTION ENSUES BEHIND THIS FRONT AS WNW WINDS SHIFT TO THE NNW OR DUE NORTH DIRECTION AND WILL USHER IN 850MB TEMPS BELOW -20C. ADDITIONALLY...A WEAKER SHORTWAVE WILL DROP SE AND REACH THE NORTHERN GREAT LAKES BY 12Z SUN. THIS SECOND WAVE WILL HELP MAINTAIN CYCLONIC FLOW ALOFT AND REINFORCE THE GREAT LAKES TROUGH WHILE KEEPING 850-700MB RH LEVELS NEARLY SATURATED. THIS APPEARS TO BE A PRETTY GOOD SETUP FROM A LAKE EFFECT STANDPOINT WITH MODEL SOUNDINGS SHOWING MAXIMUM UPWARD MOTION IN THE FAVORED DENDRITIC GROWTH AREA AND HIGH INVERSION HEIGHTS (UP TO 700 MB). HOWEVER...TIMING ISSUES STILL EXIST SINCE THE NAM BRINGS THE SECONDARY COLD FRONT ACROSS THE CWA SLOWER THAN THE GFS. UPPER LEVEL CYCLONIC FLOW CONTINUES ON SUNDAY AS THE POLAR VORTEX PASSES JUST NORTH OF THE GREAT LAKES WHILE COLD AIR ADVECTION CONTINUES. HAVE LOWERED HIGH TEMPERATURES A FEW DEGREES WITH 850MB TEMPERATURES BETWEEN -20C AND -22C. MONDAY THROUGH THURSDAY...LONG RANGE MODELS ARE IN EXCELLENT AGREEMENT WITH THE UPCOMING PATTERN FOR NEXT WEEK...AND PATTERN THAT LOOKS BITTERLY COLD FOR THE EASTERN HALF OF NORTH AMERICA. STRONG WESTERN NOAM RIDGE STRENGTHENS AS IT RETROGRADES SLIGHTLY FROM THE YUKON TO EASTERN ALASKA PRODUCING 500MB HEIGHT ANOMALIES 360 METERS ABOVE NORMAL BY 00Z WEDNESDAY. THIS WILL HELP TO CREATE UPPER LEVEL FLOW ORIGINATING DIRECTLY OUT OF THE ARCTIC AND PRODUCE 500MB HEIGHT ANOMALIES IN EXCESS OF 320 METERS BELOW NORMAL BY 00Z FRI DOWNSTREAM OVER THE GREAT LAKES. GFS ENSEMBLE MEMBERS ARE IN REMARKABLE AGREEMENT WITH THE STRENGTH OF THE RIDGE AS SHOWN BY THE LOW STANDARD DEVIATIONS WITHIN THE RIDGE AXIS WITH THE HIGHEST PERTURBATIONS ON THE PERIPHERY WHERE THE STORM TRACK WILL RESIDE. MAIN FORECAST CONCERNS INCLUDE TIMING OF THESE CLIPPERS AS THEY SLIDE DOWN THE EASTERN SIDES OF THE RIDGE...WITH EACH BRINGING A SLIGHT WARM UP AHEAD OF THEM...AND BITTERLY COLD AIR BEHIND THEM. ONE OF THESE WAVES IS EXPECTED TO APPROACH NORTHERN MICHIGAN ON TUESDAY...WITH THE NEXT ONE ARRIVING ON THURSDAY. THE LATTER OF THESE WAVES COULD POTENTIALLY BRING THE COLDEST AIR WE HAVE SEEN THUS FAR THIS WINTER. OUTSIDE OF THESE WAVES...LAKE EFFECT SNOW POTENTIAL WILL KEEP A CHANCE OF SNOW SHOWERS POSSIBLE EACH DAY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...NONE && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 732 PM EST THU JAN 25 2007 .UPDATE...WILL LOWER MIN TEMPS AT LEAST A LITTLE IN MUCH OF THE FORECAST AREA. LAKE CLOUDS ARE SLOWLY ADVECTING EASTWARD AS LOW LEVEL WINDS BACK...AND A BAND OF MID CLOUDS WERE FURTHER UPSTREAM IN WESTERN UPPER MI AND WI. THE INCREASING CLOUDS WILL KEEP THINGS FROM GETTING RIDICULOUS. HOWEVER...A FEW SITES ARE ALREADY BELOW FORECAST MINS (OSCODA AT -4F BEING THE MOST DRASTIC EXAMPLE). ZOLTOWSKI && .PREV DISCUSSION ISSUED 355 PM THU JAN 25... 20Z SATELLITE/SURFACE/AND RUC ANALYSIS SHOWS SURFACE RIDGE AXIS OVER THE WESTERN LAKES REGION SLOWLY BUILDING EAST INTO THE AREA. AT THE MID LEVELS...EASTERN CONUS LONG WAVE TROUGH BEGINNING TO GET BOOTED EAST AS POTENT SHORTWAVE OVER CENTRAL ALBERTA BEGINNING TO MAKE THE TURN SOUTHEAST ON DOWNSTREAM SIDE OF AMPLIFIED INTERMOUNTAIN RIDGE. NORTH FLOW LAKE EFFECT SNOWS...ALBEIT RATHER WEAK AND DISORGANIZED...STARTING TO TRANSITION TO MORE NORTHWESTERLY AS SURFACE RIDGE MOVES IN. CLASSIC VISIBLE SATELLITE SHOT THIS AFTERNOON SHOWING LAKE CLOUD STREAMERS IMPINGING ON THE IMMEDIATE SHORELINES OF THE LAKES WITH MOST INLAND AREAS CLOUD FREE. DESPITE THE SUN...TEMPERATURES HAVE BEEN SLOW TO RECOVER WITH CONTINUING COLD AIR ADVECTION THROUGH THE DAY AND HIGH ALBEDO WITH FRESH SNOW COVER. FORECAST CONCERNS INITIALLY CENTER ON LAKE SNOW CHANCES AND TEMPERATURES THIS EVENING WITH FOCUS THEN SHIFTING TO RAPIDLY APPROACHING AFOREMENTIONED ALBERTA SHORTWAVE. TONIGHT...DESPITE EXTREME OVER WATER INSTABILITY THIS EVENING WITH 850MB TEMPERATURES AROUND -20C (WITH CORRESPONDING DELTA T VALUES IN THE LOWER 20S CELSIUS)...OTHER FACTORS NOT SUPPORTIVE OF SIGNIFICANT LES THIS EVENING WITH ANTICYCLONIC FLOW...INVERSION HEIGHTS AT ABOUT 3.5KFT AND 850MB-700MB MOISTURE <40 PERCENT. AS WINDS CONTINUE TO BACK AROUND NORTHWESTERLY EXPECT SNOW SHOWERS TO SPREAD A LITTLE FARTHER INLAND THIS EVENING AND WILL CONTINUE SCATTERED WORDING. GIVEN ABOVE PARAMETERS NOT EXPECTING MUCH MORE THAN A COUPLE TENTHS OF AN INCH OF NEW ACCUMULATION. THEREFORE...WILL LET LAKE SNOW ADVISORIES AND WARNINGS EXPIRE AT 4 PM. AWAY FROM THE LAKE...EVENING CLEAR TO PARTLY CLOUDY SKIES WILL ALLOW TEMPERATURES TO QUICKLY DROP OFF...REACHING THE MID SINGLE DIGITS BELOW ZERO. OTHERWISE...SOME MODERATION FROM THE LAKES WILL KEEP LOWS THIS EVENING IN THE SINGLE DIGITS TO LOW TEENS. BY LATER TONIGHT...280K-290K ISENTROPIC ASCENT RAMPS UP WELL OUT AHEAD OF DEVELOPING CENTRAL PLAINS WARM FRONT. MODEL DISCREPANCIES CONTINUE WITH REGARDS TO MID LEVEL MOISTURE WITH 12Z GFS/UKMET/AND ECMWF STILL MUCH MORE AGGRESSIVE THAN NAM-WRF. GIVEN CONSISTENTLY WITH REGARDS TO FORMER SOLUTIONS AND LATEST ANALYSIS SUPPORTING MORE MOIST SCENARIO...WILL SIDE WITH THESE SOLUTIONS. THUS...WILL KEEP CHANCE POPS AFTER MIDNIGHT. ALTHOUGH RAPID WAA HELPS BOOST 850MB TEMPERATURE TO A COUPLE DEGREES EITHER SIDE OF -10C...ENOUGH INSTABILITY REMAINS FOR SOME SOUTHWEST FLOW LAKE ENHANCEMENT LATE TONIGHT AS WINDS CONTINUE TO BACK AROUND. HOWEVER...RAPIDLY BACKING WINDS BY MORNING MAY PREVENT ANY SIGNIFICANT LAKE CONTRIBUTION. GIVEN SHORT WINDOW OF EVENT DID NOT INCLUDE IN FORECAST AT THIS TIME. WILL PASS CONCERNS ALONG TO EVENING CREW. AFTER QUICK FALL OFF THIS EVENING...TEMPERATURES WILL STABILIZE AND START TO WARM SOME LATER TONIGHT WITH ONSET OF INCREASING CLOUD COVER AND SOUTHWEST RETURN FLOW AS RIDGE AXIS PASSES OFF TO THE EAST.. FRIDAY...SIDING WITH THE MORE MOIST SOLUTIONS...HAVE MAINTAINED LIKELY LIGHT SNOW WORDING DURING THE MORNING AS ISENTROPIC UPGLIDE IN CONJUNCTION WITH 850MB-650MB FRONTOGENETICAL FORCING SWINGS THROUGH. SPEED AND LIMITED MOISTURE (MIXING RATIOS ONLY ON THE ORDER OF 2 G/KG WITH PWAT VALUES OF AROUND 0.40 INCHES) SHOULD KEEP ACCUMULATIONS ON THE ORDER OF 1 TO 3 INCHES. GROWING CONCERN FOR SOME FREEZING DRIZZLE FOR THE AFTERNOON AS MODEL POINT SOUNDINGS SHOW MID LEVEL MOISTURE RAPIDLY STRIPPING AWAY ABOVE SATURATED LOW LEVELS...WHICH REMAINS BELOW -10C. GIVEN SOME CONSISTENCY IN THIS REGARDS DID BRING IN CHANCE OF FREEZING DRIZZLE IN COMBINATION WITH THE LIGHT SNOW DURING THE AFTERNOON. TEMPERATURES WILL BE SEVERAL DEGREES WARMER THAN TODAYS READINGS...REACHING HIGHS IN THE MID 20S TO NEAR 30. MARINE...EXTENDED SCA FOR LAKE HURON NEARSHORE WATERS BORDERING NORTHERN LOWER MICHIGAN THROUGH 04Z TO ACCOUNT FOR LINGERING WIND GUSTS AND SOME CONVERGENCE WITH FAVORED NORTHWEST FLOW. MSB LATER PERIODS...MEDIUM RANGE MODELS/ENSEMBLES CONTINUE TO BE IN VERY GOOD AGREEMENT WITH THE UPCOMING COLD PATTERN. MAIN FORECAST CONCERNS THROUGH NEXT WEEK WILL CONTINUE TO REVOLVE AROUND A SERIES OF NORTHERN STREAM SYSTEMS THAT WILL DROP SOUTHEAST TOWARDS THE GREAT LAKES...EACH SEPARATED BY COUPLE DAYS OR SO. MODELS INDICATE A STRONG RIDGE DEVELOPING BY EARLY NEXT WEEK...WITH THE FLOW ACROSS THE GREAT LAKES ORIGINATING OUT OF THE ARCTIC. IN THE SHORT TERM...HOWEVER...GFS AND THE EUROPEAN MODELS HAVE BEEN SHOWING DECENT CONTINUITY OVER THE LAST DAY OR SO...UNLIKE THE NAM WHICH SEEMS TO BE TRYING TO CATCH UP WITH THE PREVIOUSLY MENTIONED MODELS. THEREFORE...THIS FORECAST CONSISTS OF A BLEND BETWEEN THE GFS/ECMWF/UKMET MODELS. FRIDAY NIGHT INTO SATURDAY...GFS ENSEMBLE/GFS/UKMET/ECMWF AGREE WELL WITH THE TRACK OF THE CLIPPER SYSTEM AND TRACK OF ITS ASSOCIATED SURFACE LOW ACROSS THE STRAITS. THIS SURFACE LOW AND LEADING COLD FRONT WILL PASS ACROSS NORTHERN MICHIGAN FRIDAY NIGHT. MOISTURE DEPTH IS A CONCERN DURING THE EVENING HOURS...ESPECIALLY ACROSS NORTHERN LOWER WHERE THE MOISTURE STRUGGLES TO REACH -10C. THIS IS NOT SO MUCH OF A PROBLEM ACROSS EASTERN UPPER...CLOSER TO THE SHORTWAVE. WILL THEREFORE HAVE TO MENTION A CHANCE OF FREEZING DRIZZLE ACROSS NORTHERN LOWER DURING THE EVENING BEFORE COLD ADVECTION AND DEEPER MOISTURE ARRIVES OVERNIGHT. 1000-850MB WINDS SHIFT TO WNW BEHIND THE COLD FRONT...BRINGING LAKES MICHIGAN AND SUPERIOR BACK INTO PLAY (ALBEIT MARGINALLY) AS 850MB TEMPERATURES COOL TO AROUND BY -10C TO -12C BY 12Z AND -12C TO -16C BY 18Z. WITH THE STRONGEST FORCING AND COLDER THERMODYNAMIC PROFILE LYING ACROSS EASTERN UPPER...HAVE DECIDED TO UP POPS TO LIKELY ACROSS WESTERN CHIPPEWA COUNTY. SHORTWAVE AND SECONDARY COLD FRONT THEN SWINGS SOUTH AND CLEARS ALL BUT THE SOUTHERN FRINGES OF THE CWA BY 00Z SATURDAY. 1000-850MB WINDS THEN SHIFT TO NNW BEHIND THIS SECOND FRONT BRINGING IN MUCH COLDER AIR ONCE AGAIN. HAVE THROWN UP A LIKELY POP OVER PORTIONS OF NW LOWER MICHIGAN WHERE THE COMBINATION OF WNW AND NNW FLOW SEEM TO CONVERGE TO PRODUCE THE BEST CHANCE OF PRECIP. SATURDAY NIGHT INTO SUNDAY... SHORTWAVE AND SECONDARY COLD FRONT MOVE SOUTH AND CLEAR THE CWA DURING THE EVENING HOURS. STRONG COLD ADVECTION ENSUES BEHIND THIS FRONT AS WNW WINDS SHIFT TO THE NNW OR DUE NORTH DIRECTION AND WILL USHER IN 850MB TEMPS BELOW -20C. ADDITIONALLY...A WEAKER SHORTWAVE WILL DROP SE AND REACH THE NORTHERN GREAT LAKES BY 12Z SUN. THIS SECOND WAVE WILL HELP MAINTAIN CYCLONIC FLOW ALOFT AND REINFORCE THE GREAT LAKES TROUGH WHILE KEEPING 850-700MB RH LEVELS NEARLY SATURATED. THIS APPEARS TO BE A PRETTY GOOD SETUP FROM A LAKE EFFECT STANDPOINT WITH MODEL SOUNDINGS SHOWING MAXIMUM UPWARD MOTION IN THE FAVORED DENDRITIC GROWTH AREA AND HIGH INVERSION HEIGHTS (UP TO 700 MB). HOWEVER...TIMING ISSUES STILL EXIST SINCE THE NAM BRINGS THE SECONDARY COLD FRONT ACROSS THE CWA SLOWER THAN THE GFS. UPPER LEVEL CYCLONIC FLOW CONTINUES ON SUNDAY AS THE POLAR VORTEX PASSES JUST NORTH OF THE GREAT LAKES WHILE COLD AIR ADVECTION CONTINUES. HAVE LOWERED HIGH TEMPERATURES A FEW DEGREES WITH 850MB TEMPERATURES BETWEEN -20C AND -22C. MONDAY THROUGH THURSDAY...LONG RANGE MODELS ARE IN EXCELLENT AGREEMENT WITH THE UPCOMING PATTERN FOR NEXT WEEK...AND PATTERN THAT LOOKS BITTERLY COLD FOR THE EASTERN HALF OF NORTH AMERICA. STRONG WESTERN NOAM RIDGE STRENGTHENS AS IT RETROGRADES SLIGHTLY FROM THE YUKON TO EASTERN ALASKA PRODUCING 500MB HEIGHT ANOMALIES 360 METERS ABOVE NORMAL BY 00Z WEDNESDAY. THIS WILL HELP TO CREATE UPPER LEVEL FLOW ORIGINATING DIRECTLY OUT OF THE ARCTIC AND PRODUCE 500MB HEIGHT ANOMALIES IN EXCESS OF 320 METERS BELOW NORMAL BY 00Z FRI DOWNSTREAM OVER THE GREAT LAKES. GFS ENSEMBLE MEMBERS ARE IN REMARKABLE AGREEMENT WITH THE STRENGTH OF THE RIDGE AS SHOWN BY THE LOW STANDARD DEVIATIONS WITHIN THE RIDGE AXIS WITH THE HIGHEST PERTURBATIONS ON THE PERIPHERY WHERE THE STORM TRACK WILL RESIDE. MAIN FORECAST CONCERNS INCLUDE TIMING OF THESE CLIPPERS AS THEY SLIDE DOWN THE EASTERN SIDES OF THE RIDGE...WITH EACH BRINGING A SLIGHT WARM UP AHEAD OF THEM...AND BITTERLY COLD AIR BEHIND THEM. ONE OF THESE WAVES IS EXPECTED TO APPROACH NORTHERN MICHIGAN ON TUESDAY...WITH THE NEXT ONE ARRIVING ON THURSDAY. THE LATTER OF THESE WAVES COULD POTENTIALLY BRING THE COLDEST AIR WE HAVE SEEN THUS FAR THIS WINTER. OUTSIDE OF THESE WAVES...LAKE EFFECT SNOW POTENTIAL WILL KEEP A CHANCE OF SNOW SHOWERS POSSIBLE EACH DAY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...NONE && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 355 PM EST THU JAN 25 2007 .DISCUSSION...20Z SATELLITE/SURFACE/AND RUC ANALYSIS SHOWS SURFACE RIDGE AXIS OVER THE WESTERN LAKES REGION SLOWLY BUILDING EAST INTO THE AREA. AT THE MID LEVELS...EASTERN CONUS LONG WAVE TROUGH BEGINNING TO GET BOOTED EAST AS POTENT SHORTWAVE OVER CENTRAL ALBERTA BEGINNING TO MAKE THE TURN SOUTHEAST ON DOWNSTREAM SIDE OF AMPLIFIED INTERMOUNTAIN RIDGE. NORTH FLOW LAKE EFFECT SNOWS...ALBEIT RATHER WEAK AND DISORGANIZED...STARTING TO TRANSITION TO MORE NORTHWESTERLY AS SURFACE RIDGE MOVES IN. CLASSIC VISIBLE SATELLITE SHOT THIS AFTERNOON SHOWING LAKE CLOUD STREAMERS IMPINGING ON THE IMMEDIATE SHORELINES OF THE LAKES WITH MOST INLAND AREAS CLOUD FREE. DESPITE THE SUN...TEMPERATURES HAVE BEEN SLOW TO RECOVER WITH CONTINUING COLD AIR ADVECTION THROUGH THE DAY AND HIGH ALBEDO WITH FRESH SNOW COVER. FORECAST CONCERNS INITIALLY CENTER ON LAKE SNOW CHANCES AND TEMPERATURES THIS EVENING WITH FOCUS THEN SHIFTING TO RAPIDLY APPROACHING AFOREMENTIONED ALBERTA SHORTWAVE. TONIGHT...DESPITE EXTREME OVER WATER INSTABILITY THIS EVENING WITH 850MB TEMPERATURES AROUND -20C (WITH CORRESPONDING DELTA T VALUES IN THE LOWER 20S CELSIUS)...OTHER FACTORS NOT SUPPORTIVE OF SIGNIFICANT LES THIS EVENING WITH ANTICYCLONIC FLOW...INVERSION HEIGHTS AT ABOUT 3.5KFT AND 850MB-700MB MOISTURE <40 PERCENT. AS WINDS CONTINUE TO BACK AROUND NORTHWESTERLY EXPECT SNOW SHOWERS TO SPREAD A LITTLE FARTHER INLAND THIS EVENING AND WILL CONTINUE SCATTERED WORDING. GIVEN ABOVE PARAMETERS NOT EXPECTING MUCH MORE THAN A COUPLE TENTHS OF AN INCH OF NEW ACCUMULATION. THEREFORE...WILL LET LAKE SNOW ADVISORIES AND WARNINGS EXPIRE AT 4 PM. AWAY FROM THE LAKE...EVENING CLEAR TO PARTLY CLOUDY SKIES WILL ALLOW TEMPERATURES TO QUICKLY DROP OFF...REACHING THE MID SINGLE DIGITS BELOW ZERO. OTHERWISE...SOME MODERATION FROM THE LAKES WILL KEEP LOWS THIS EVENING IN THE SINGLE DIGITS TO LOW TEENS. BY LATER TONIGHT...280K-290K ISENTROPIC ASCENT RAMPS UP WELL OUT AHEAD OF DEVELOPING CENTRAL PLAINS WARM FRONT. MODEL DISCREPANCIES CONTINUE WITH REGARDS TO MID LEVEL MOISTURE WITH 12Z GFS/UKMET/AND ECMWF STILL MUCH MORE AGGRESSIVE THAN NAM-WRF. GIVEN CONSISTENTLY WITH REGARDS TO FORMER SOLUTIONS AND LATEST ANALYSIS SUPPORTING MORE MOIST SCENARIO...WILL SIDE WITH THESE SOLUTIONS. THUS...WILL KEEP CHANCE POPS AFTER MIDNIGHT. ALTHOUGH RAPID WAA HELPS BOOST 850MB TEMPERATURE TO A COUPLE DEGREES EITHER SIDE OF -10C...ENOUGH INSTABILITY REMAINS FOR SOME SOUTHWEST FLOW LAKE ENHANCEMENT LATE TONIGHT AS WINDS CONTINUE TO BACK AROUND. HOWEVER...RAPIDLY BACKING WINDS BY MORNING MAY PREVENT ANY SIGNIFICANT LAKE CONTRIBUTION. GIVEN SHORT WINDOW OF EVENT DID NOT INCLUDE IN FORECAST AT THIS TIME. WILL PASS CONCERNS ALONG TO EVENING CREW. AFTER QUICK FALL OFF THIS EVENING...TEMPERATURES WILL STABILIZE AND START TO WARM SOME LATER TONIGHT WITH ONSET OF INCREASING CLOUD COVER AND SOUTHWEST RETURN FLOW AS RIDGE AXIS PASSES OFF TO THE EAST.. FRIDAY...SIDING WITH THE MORE MOIST SOLUTIONS...HAVE MAINTAINED LIKELY LIGHT SNOW WORDING DURING THE MORNING AS ISENTROPIC UPGLIDE IN CONJUNCTION WITH 850MB-650MB FRONTOGENETICAL FORCING SWINGS THROUGH. SPEED AND LIMITED MOISTURE (MIXING RATIOS ONLY ON THE ORDER OF 2 G/KG WITH PWAT VALUES OF AROUND 0.40 INCHES) SHOULD KEEP ACCUMULATIONS ON THE ORDER OF 1 TO 3 INCHES. GROWING CONCERN FOR SOME FREEZING DRIZZLE FOR THE AFTERNOON AS MODEL POINT SOUNDINGS SHOW MID LEVEL MOISTURE RAPIDLY STRIPPING AWAY ABOVE SATURATED LOW LEVELS...WHICH REMAINS BELOW -10C. GIVEN SOME CONSISTENCY IN THIS REGARDS DID BRING IN CHANCE OF FREEZING DRIZZLE IN COMBINATION WITH THE LIGHT SNOW DURING THE AFTERNOON. TEMPERATURES WILL BE SEVERAL DEGREES WARMER THAN TODAYS READINGS...REACHING HIGHS IN THE MID 20S TO NEAR 30. MARINE...EXTENDED SCA FOR LAKE HURON NEARSHORE WATERS BORDERING NORTHERN LOWER MICHIGAN THROUGH 04Z TO ACCOUNT FOR LINGERING WIND GUSTS AND SOME CONVERGENCE WITH FAVORED NORTHWEST FLOW. MSB LATER PERIODS...MEDIUM RANGE MODELS/ENSEMBLES CONTINUE TO BE IN VERY GOOD AGREEMENT WITH THE UPCOMING COLD PATTERN. MAIN FORECAST CONCERNS THROUGH NEXT WEEK WILL CONTINUE TO REVOLVE AROUND A SERIES OF NORTHERN STREAM SYSTEMS THAT WILL DROP SOUTHEAST TOWARDS THE GREAT LAKES...EACH SEPARATED BY COUPLE DAYS OR SO. MODELS INDICATE A STRONG RIDGE DEVELOPING BY EARLY NEXT WEEK...WITH THE FLOW ACROSS THE GREAT LAKES ORIGINATING OUT OF THE ARCTIC. IN THE SHORT TERM...HOWEVER...GFS AND THE EUROPEAN MODELS HAVE BEEN SHOWING DECENT CONTINUITY OVER THE LAST DAY OR SO...UNLIKE THE NAM WHICH SEEMS TO BE TRYING TO CATCH UP WITH THE PREVIOUSLY MENTIONED MODELS. THEREFORE...THIS FORECAST CONSISTS OF A BLEND BETWEEN THE GFS/ECMWF/UKMET MODELS. FRIDAY NIGHT INTO SATURDAY...GFS ENSEMBLE/GFS/UKMET/ECMWF AGREE WELL WITH THE TRACK OF THE CLIPPER SYSTEM AND TRACK OF ITS ASSOCIATED SURFACE LOW ACROSS THE STRAITS. THIS SURFACE LOW AND LEADING COLD FRONT WILL PASS ACROSS NORTHERN MICHIGAN FRIDAY NIGHT. MOISTURE DEPTH IS A CONCERN DURING THE EVENING HOURS...ESPECIALLY ACROSS NORTHERN LOWER WHERE THE MOISTURE STRUGGLES TO REACH -10C. THIS IS NOT SO MUCH OF A PROBLEM ACROSS EASTERN UPPER...CLOSER TO THE SHORTWAVE. WILL THEREFORE HAVE TO MENTION A CHANCE OF FREEZING DRIZZLE ACROSS NORTHERN LOWER DURING THE EVENING BEFORE COLD ADVECTION AND DEEPER MOISTURE ARRIVES OVERNIGHT. 1000-850MB WINDS SHIFT TO WNW BEHIND THE COLD FRONT...BRINGING LAKES MICHIGAN AND SUPERIOR BACK INTO PLAY (ALBEIT MARGINALLY) AS 850MB TEMPERATURES COOL TO AROUND BY -10C TO -12C BY 12Z AND -12C TO -16C BY 18Z. WITH THE STRONGEST FORCING AND COLDER THERMODYNAMIC PROFILE LYING ACROSS EASTERN UPPER...HAVE DECIDED TO UP POPS TO LIKELY ACROSS WESTERN CHIPPEWA COUNTY. SHORTWAVE AND SECONDARY COLD FRONT THEN SWINGS SOUTH AND CLEARS ALL BUT THE SOUTHERN FRINGES OF THE CWA BY 00Z SATURDAY. 1000-850MB WINDS THEN SHIFT TO NNW BEHIND THIS SECOND FRONT BRINGING IN MUCH COLDER AIR ONCE AGAIN. HAVE THROWN UP A LIKELY POP OVER PORTIONS OF NW LOWER MICHIGAN WHERE THE COMBINATION OF WNW AND NNW FLOW SEEM TO CONVERGE TO PRODUCE THE BEST CHANCE OF PRECIP. SATURDAY NIGHT INTO SUNDAY... SHORTWAVE AND SECONDARY COLD FRONT MOVE SOUTH AND CLEAR THE CWA DURING THE EVENING HOURS. STRONG COLD ADVECTION ENSUES BEHIND THIS FRONT AS WNW WINDS SHIFT TO THE NNW OR DUE NORTH DIRECTION AND WILL USHER IN 850MB TEMPS BELOW -20C. ADDITIONALLY...A WEAKER SHORTWAVE WILL DROP SE AND REACH THE NORTHERN GREAT LAKES BY 12Z SUN. THIS SECOND WAVE WILL HELP MAINTAIN CYCLONIC FLOW ALOFT AND REINFORCE THE GREAT LAKES TROUGH WHILE KEEPING 850-700MB RH LEVELS NEARLY SATURATED. THIS APPEARS TO BE A PRETTY GOOD SETUP FROM A LAKE EFFECT STANDPOINT WITH MODEL SOUNDINGS SHOWING MAXIMUM UPWARD MOTION IN THE FAVORED DENDRITIC GROWTH AREA AND HIGH INVERSION HEIGHTS (UP TO 700 MB). HOWEVER...TIMING ISSUES STILL EXIST SINCE THE NAM BRINGS THE SECONDARY COLD FRONT ACROSS THE CWA SLOWER THAN THE GFS. UPPER LEVEL CYCLONIC FLOW CONTINUES ON SUNDAY AS THE POLAR VORTEX PASSES JUST NORTH OF THE GREAT LAKES WHILE COLD AIR ADVECTION CONTINUES. HAVE LOWERED HIGH TEMPERATURES A FEW DEGREES WITH 850MB TEMPERATURES BETWEEN -20C AND -22C. MONDAY THROUGH THURSDAY...LONG RANGE MODELS ARE IN EXCELLENT AGREEMENT WITH THE UPCOMING PATTERN FOR NEXT WEEK...AND PATTERN THAT LOOKS BITTERLY COLD FOR THE EASTERN HALF OF NORTH AMERICA. STRONG WESTERN NOAM RIDGE STRENGTHENS AS IT RETROGRADES SLIGHTLY FROM THE YUKON TO EASTERN ALASKA PRODUCING 500MB HEIGHT ANOMALIES 360 METERS ABOVE NORMAL BY 00Z WEDNESDAY. THIS WILL HELP TO CREATE UPPER LEVEL FLOW ORIGINATING DIRECTLY OUT OF THE ARCTIC AND PRODUCE 500MB HEIGHT ANOMALIES IN EXCESS OF 320 METERS BELOW NORMAL BY 00Z FRI DOWNSTREAM OVER THE GREAT LAKES. GFS ENSEMBLE MEMBERS ARE IN REMARKABLE AGREEMENT WITH THE STRENGTH OF THE RIDGE AS SHOWN BY THE LOW STANDARD DEVIATIONS WITHIN THE RIDGE AXIS WITH THE HIGHEST PERTURBATIONS ON THE PERIPHERY WHERE THE STORM TRACK WILL RESIDE. MAIN FORECAST CONCERNS INCLUDE TIMING OF THESE CLIPPERS AS THEY SLIDE DOWN THE EASTERN SIDES OF THE RIDGE...WITH EACH BRINGING A SLIGHT WARM UP AHEAD OF THEM...AND BITTERLY COLD AIR BEHIND THEM. ONE OF THESE WAVES IS EXPECTED TO APPROACH NORTHERN MICHIGAN ON TUESDAY...WITH THE NEXT ONE ARRIVING ON THURSDAY. THE LATTER OF THESE WAVES COULD POTENTIALLY BRING THE COLDEST AIR WE HAVE SEEN THUS FAR THIS WINTER. OUTSIDE OF THESE WAVES...LAKE EFFECT SNOW POTENTIAL WILL KEEP A CHANCE OF SNOW SHOWERS POSSIBLE EACH DAY. MPC && .APX WATCHES/WARNINGS/ADVISORIES...NONE && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 313 PM EST THU JAN 25 2007 .SHORT TERM DISCUSSION (TONIGHT)... 12Z RAOBS/WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE TROF IN ERN NAMERICA DOWNSTREAM OF RDG OVER THE ROCKIES. LES OVER THE FA DOWNWIND OF LK SUP IN COLD NW FLOW BTWN ARCTIC HI PRES OVER ONTARIO AND LO PRES IN THE LOWER GREAT LKS IS ON THE DIMINISHING TREND AS VERY DRY/STABLE AIR SHOWN ON UPSTREAM 12Z RAOBS/TAMDAR SDNG FM CYQT (INVRN BASE H925-95 AND PWAT AS LO AS 0.05 INCH) MOVES OVER THE UPR LKS UNDER BLDG H5 HGTS/ INCRSG LARGER SCALE ACYC FLOW DESPITE SOME LINGERING CNVGC ALG LK INDUCED TROFFING EXTENDING FM LO TO THE SE NW ACRS LK HURON INTO ALGER COUNTY/CNTRL LK SUP. UPSTREAM...A SHRTWV MOVING INTO NRN ALBERTA/SASKATCHEWAN IS TOPPING THE ROCKIES RDG. QUITE A BIT OF MID CLD AND EVEN SOME PTCHY -SN NOTED FM SCNTRL CAN INTO NE ND/NW MN IN THE SW FLOW/WAD PATTERN BTWN LO PRES ASSOCIATED WITH THIS SHRTWV AND THE HI PRES SYS OVER ONTARIO AND THE UPR MS RIVER VALLEY. PWAT 0.44 INCH AT YQD...SO THERE IS MORE MSTR AVBL TO THIS SHRTWV. MAIN FCST CONCERNS IN THE SHORT TERM ARE LINGERING LES TRENDS AND -SN CHCS ASSOCIATED WITH SHRTWV NOW TOPPING ROCKIES RDG. FOR TNGT...GUIDANCE SHOWS RISING HGTS OVER THE UPR GRT LKS IN ADVANCE OF SHRTWV NOW OVER NRN ALBERTA/SASKATCHEWAN...WHICH IS FCST TO REACH NR LK WINNIPEG BY 12Z FRI. AS HGTS RISE AND SFC RDG AXIS/ LOWER INVRN BASE/DEEPER DRY AIR PASSES ACRS THE CWA THIS EVNG UNDER THE RISING HGTS...EXPECT LES TO DIMINISH AND THEN END WITH LTL ADDITIONAL ACCUMULATION. WL LET ANY GOING HEADLINES EXPIRE AS SCHEDULED. ALTHOUGH SKIES WL BE PCLDY FOR A TIME WITH ARRIVAL OF RDG AXIS (EXCEPT OVER THE KEWEENAW WITH BKN-OVC SC LINGERING IN W-SW FLOW EVEN ON BACK SIDE OF RDG)...NAM/GFS SHOW ISENTROPIC LIFT ON THE 280-290K SFCS OVERSPREADING THE FA QUICKLY AS SW RETURN FLOW DVLPS IN THE WAKE OF DEPARTING SFC RDG. GFS IS MOST AGGRESSIVE AT PUSHING HIER MID LVL MSTR TO THE E...AND USED ITS 280K SFC RH AOA 70 PCT TO TIME ARRIVAL OF MID CLD AS THIS PROG APPEARS TO CORRELATE WELL WITH OBSVD HI SC/LO AC CLD UPSTREAM. NAM FCSTS LLVLS BLO THE MID CLD DECK REMAINING SO DRY THAT MODEL QPF IS ZERO...BUT GFS GENERATES SOME LGT PCPN UNDER THE STRONGER ISENTROPIC LIFT AFT ABOUT 03Z OR SO OVER THE W AND ACRS THE ENTIRE CWA AFT 06Z WITH ARRIVAL OF UPR DVGC IN RRQ OF H3 JET MAX FCST TO MOVE OVER SE ONTARIO BY 12Z FRI. GFS FCST SDNGS ARE QUITE A BIT MORE MOIST THRU MOST OF THE TROP IN LINE WITH OBSVD 12Z YQD SDNG...BUT MODEL FCST SDNGS DO SHOW LINGERING DRY LYR BTWN H75-55...WHICH WOULD ALSO BE THE PRIME DENDRITIC SN GROWTH LYR. CONSIDERING THIS DRY LYR AS WELL AS ANTECEDENT DRY AIR...LIMITED COVG OF OBSVD SN UPSTREAM...AND NAM FCST...HAVE OPTED TO RETAIN POPS BUT CUT VALUES FM HI CHC TO LWR CHC IN LINE WITH GFS MOS GUIDANCE. AS FOR TEMPS...EXPECT MIN TEMPS RELATIVELY EARLY BEFORE THICKER MID CLD/A BIT STRONGER SW FLOW DVLPS W-E AFT EARLY THIS EVNG. KC .LONG TERM (FRIDAY THROUGH THURSDAY)... THE MAIN FORECAST CONCERN FOR THIS PORTION OF THE FORECAST REMAINS THE LAKE EFFECT SNOW EVENT FOR LATE FRIDAY NIGHT THROUGH MUCH OF THE WEEKEND. ONCE AGAIN FOR THIS PERIOD...AM GENERALLY DISCOUNTING THE NAM...AS IT IS OUT OF BOUNDS WHEN COMPARED TO THE GLOBAL MODELS. AS A RESULT...HAVE LEANED THIS FORECAST CLOSER TO THE GFS SOLUTION. GFS OFF OF BUFKIT IS PUTTING OUT OVER HALF AN INCH OF QFP OVER IWD DURING THE NEXT 5 DAYS. CONTINUE TO MONITOR THE TRACK OF THE SURFACE LOW...CURRENTLY CENTERED OVER THE SOUTHERN NORTHWEST TERRITORIES SLIDING INTO NORTHERN SASKATCHEWAN. THIS LOW WILL SLIDE SOUTHEASTWARD...AND OVER THE WESTERN HALF OF LAKE SUPERIOR BY FRIDAY AFTERNOON AND THEN SOUTHEASTWARD OVER LAKE HURON BY 12Z SATURDAY. THIS WILL FIRST ALLOW FOR A LONG SOUTHERLY FETCH ACROSS LAKE MICHIGAN LATE FRIDAY MORNING THROUGH EARLY AFTERNOON (GENERALLY 2 TO 4 INCHES OF SNOW EXPECTED ACROSS THIS AREA FRIDAY)...AND THEN SWING THE WINDS OUT OF A GENERALLY NORTH TO NORTHWESTERLY DIRECTION FRIDAY NIGHT (AND KEEP THEM BETWEEN 300 AND 030 THROUGH TUESDAY). 850MB TEMPERATURES...AFTER WARMING TO -7C OR SO FRIDAY WILL COOL DOWN TO -12C ACROSS THE AREA BY 12Z SATURDAY...ALLOWING FOR A BETTER CHANCE OF LAKE EFFECT OR LAKE ENHANCED SNOW. 850MB TEMPERATURES WILL THEN SLOWLY COOL TO -20 TO -22C BY 06Z SUNDAY. GIVEN THIS...HAVE HOISTED LAKE EFFECT SNOW WATCHES FOR GOGEBIC...ONTONAGON...MARQUETTE...AND ALGER COUNTIES FOR SATURDAY MORNING THROUGH MID DAY SUNDAY. FOR FRIDAY NIGHT HAVE ADJUSTED TEMPS DOWN A COUPLE OF DEGREES ACROSS OUR CLIMATOLOGICALLY COOLER SOUTH CENTRAL CWA...WITH THE IDEA THAT THE DRY SLOT MAY COME IN EARLY AND ALLOW TEMPS TO DROP. FIRST COLD FRONT IS EXPECTED TO CROSS THE CWA LATE FRIDAY AFTERNOON THROUGH 06Z SATURDAY. COOLER TEMPS ALOFT WILL TAKE A BIT LONGER TO SLIDE IN. EXPECT THE SINGLE DIGITS TO LOW TEENS FOR HIGH TEMPERATURES SUNDAY...AS THE COLDEST AIR SINKS OVERHEAD. WINDS BACK SLIGHTLY SUNDAY...ADDING TO THE CONVERGENCE OVER THE EASTERN THIRD OF THE LAKE SUPERIOR SHORELINE FROM MUNISING EAST. AS HAS BEEN THE TREND OVER THE LAST COUPLE OF SHIFTS...HAVE INCREASED POPS HERE TO DEFINITE. AS FOR RIGHT NOW...DO NOT HAVE ANY WATCHES/WARNINGS OR ADVISORIES POSTED FOR THE EASTERN PORTIONS OF THE CWA (EXCEPT ALGER COUNTY)...BUT AS THE TIME NEARS HEADLINES WILL LIKELY BE NEEDED. MONDAY THROUGH THURSDAY (DAYS 4-7)...WITH THE RELATIVE CONSISTENCY IN THE EXTENDED RANGE...WITH LESS MODEL FLIP FLOPPING THAN USUAL...FEW CHANGES WERE MADE...PARTICULARLY TO TEMPERATURES. STILL...DID COOL DOWN TEMPERATURES ROUGHLY 4 DEGREES ACROSS THE BOARD MONDAY AFTERNOON. SO THE OVERALL PATTERN INCLUDES A SERIES OF SHORTWAVES IN THE POLAR/ARCTIC JET CONTINUALLY RE-ENFORCING OUR ALREADY COLD AIRMASS. MONDAY 12Z...LOOKING AT THE MID LEVELS...THE GFS AND ECMWF BEGIN TO BECOME A LITTLE MORE NOTICEABLE IN THERE DIFFERENCES. THE 500MB DEPICTED BY THE GFS...ALTHOUGH SIMILAR IN STRENGTH IS ABLE TO SLIDE FURTHER SOUTHWARD...MAKING IT INTO EASTERN LAKE HURON BY THIS TIME...WHILE THE ECMWF HAS IT REMAINING OVER EASTERN HUDSON BAY. AS PREVIOUSLY STATED...GENERALLY DISREGARDED THIS DISCREPANCY...AND SIDED CLOSER TO THE GFS SOLUTION. UPDATED AND INCREASED CLOUD COVER FOR MONDAY INTO MONDAY NIGHT...AS SHORTWAVE SLIDES IN FROM THE NORTHWEST...ACCORDING TO THE 06Z GFS. ALTHOUGH IT SEEMS THAT THE SHORTWAVE HAS DROPPED FURTHER SOUTH FOR THE 12Z GFS RUN...STILL BELIEVE THAT WE WILL HAVE MORE THAN 40 PERCENT CLOUD COVER FOR THIS PERIOD...SO HAVE KEPT THE ADJUSTED MORE PESSIMISTIC CLOUD FOR MONDAY INTO MONDAY NIGHT. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WATCH FROM SATURDAY MORNING THROUGH SUNDAY AFTERNOON FOR MIZ005-006. LAKE EFFECT SNOW WATCH FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING FOR MIZ002-009. && $$ .SHORT TERM...KC .LONG TERM...KF mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 1000 AM EST THU JAN 25 2007 .UPDATE... 12Z RAOBS/WV IMAGERY AND RUC ANALYSIS SHOW HI AMPLITUDE TROF IN ERN NAMERICA DOWNSTREAM OF RDG OVER THE ROCKIES. LES CONTINUES OVER THE FA DOWNSTREAM OF LK SUP IN COLD N FLOW BTWN HI PRES IN NW ONTARIO AND LO PRES TROF EXTENDING FM LK HURON INTO CNTRL LK SUP. 12Z TAMDAR SDNG FM SAW SHOWS INVRN AT H825 WITH BASE TEMP A CHILLY -25C. RUC ANALYSIS SHOWS H85 THERMAL TROF OVER LK SUP ATTM. SPOTTER REPORT FM EBEN JUNCTION IN WRN ALGER COUNTY INDICATES 8 INCHES FELL THERE DURING THE NGT WHERE HEAVIER LES BAND LINGERED LONGER. REPORTS IN GOGEBIC COUNTY/ERN MQT COUNTY SHOW 4-6 INCHES ACCUMULATION. HOWEVER... THE OVERALL SHSN INTENSITY/COVG HAS BEEN DIMINISHED SOMEWHAT BY VERY DRY/STABLE AIR UPSTREAM OVER ONTARIO ASSOCIATED WITH THE ARCTIC HI PRES. SFC DWPTS -30F TO -40F WDSPRD OVER ONTARIO N OF LK SUP...AND 12Z TAMDAR SDNG FM YQT AS WELL AS RAOBS FM INL/YPL SHOW INVRN BASE H925-95 AND PWAT 0.05-0.10 INCH. IN FACT DESPITE LLVL CNVGC ALG TROF IN ALGER COUNTY BTWN NW LAND BREEZE FM THE W AND MORE NNE FLOW OVER THE E OFF ONTARIO...MQT 88D SHOWS LES BANDS HAVE BECOME RATHER DISORGANIZED WITH IMPACT OF DRY/STABLE ADVCTN AS WELL AS SOME DIRECTIONAL SHEAR IN THE SUB INVRN LYR DEPICTED ON MQT VWP. FEW REFLECTIVITIES ABV 20DBZ REMAIN. SHORTER FETCH/LAND BREEZE FLOW OFF ONTARIO HAVE PRETTY MUCH ENDED THE LES OVER THE FAR ERN CWA. SFC TEMP IN CHIPPEWA COUNTY HAS FALLEN TO ARND -10F WITH DRIER FLOW. MAIN FCST CONCERNS TDAY INVOLVE LES TRENDS/ADDITIONAL AMTS/GOING HEADLINES. FOR TDAY...GUIDANCE SHOWS HGT RISES BLDG HI PRES INTO THE UPR GRT LKS. ARRIVAL OF MORE ACYC FLOW/LOWER INVRN HGT WL DIMINISH THE LES W-E. IN FACT...EXPECT THE SHSN TO END OVER THE W AT IWD THIS AFTN AS LLVL FLOW BACKS TO THE SW. GOING FCST HAS THESE LARGE SCALE TRENDS WELL IN HAND...SO NEED TO MAKE ONLY MINOR ADJUSTMENTS TO FCST WX AND SN AMTS. WL ALLOW GOING HEADLINES TO CONT/EXPIRE AS FCST. EXCEPT TO BUMP UP FCST HI TEMPS AT A FEW PLACES MAINLY NR LK SUP BASED ON CURRENT TEMPS...ONLY A FEW TWEAKS NECESSARY TO GOING MAX TEMPS FCST. KC .PREVIOUS DISCUSSION (ISSUED AT 404 AM)... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING FROM SOUTHERN CALIFORNIA INTO NORTHERN ALBERTA WHILE UPPER TROUGHING DOMINATED SE CANADA INTO THE GREAT LAKES. WITHIN THIS TROUGH...A SHRTWV CAN BE SEEN DIVING SOUTHWARD THROUGH NORTHERN ONTARIO...NOW NEAR WAWA. 850MB TEMPS ASSOCIATED WITH THIS SHRTWV APPEAR TO BE AROUND -25C BASED ON 00Z RAOBS FROM MOOSONEE AND PICKLE LAKE. ALTHOUGH THE AIR IS QUITE COLD WITH THE SHRTWV...VERY LITTLE IS OCCURRING ON IR IMAGERY WITH IT DUE TO THE PRESENCE OF VERY DRY AIR (PRECIPITABLE WATER OF 0.04 INCHES ON THE PICKLE LAKE SOUNDING). SURFACE TEMPERATURES AND DEWPOINTS ALSO DEPICT THE SAME STORY OVER NORTHERN ONTARIO...WITH READINGS WELL BELOW ZERO F. THE COLD AND DRY AIR CONTINUES TO FLOW ACROSS LAKE SUPERIOR ON NORTHERLY WINDS BETWEEN A 1032MB HIGH OVER NW ONTARIO AND A LOW PRESSURE TROUGH THAT EXTENDS FROM LAKE ERIE TO SOUTHERN WISCONSIN. A LAKE INDUCED TROUGH ALSO EXTENDS FROM LAKE ERIE NW TO NEAR ONTONAGON. PLENTY OF LAKE EFFECT SNOW SHOWERS EXIST DUE TO THE COLD AIR FLOWING OVER 2-3C WATER TEMPS. CURRENT RADAR IMAGERY SHOWS A FEW DISORGANIZED BANDS IN ALGER AND EASTERN MARQUETTE COUNTIES...THOUGH THERE ARE A FEW 28DBZ PIXELS WITHIN THEM. THERE WERE ALSO SOME INTENSE BANDS OCCURRING IN THE FAR WESTERN U.P. OVERNIGHT...WITH THE BESSEMER AREA PICKING UP AROUND 6 INCHES SINCE 7 PM CST PER THE COUNTY SHERIFF. HOWEVER... OVER THE PAST FEW HOURS...THE SATELLITE APPEARANCE HAS GREATLY DIMINISHED FOR THE LAKE EFFECT BANDS ON WESTERN LAKE SUPERIOR. TO OUR NW...A 130 KT JET STREAK IS MOVING THROUGH WESTERN ONTARIO. UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION IS HELPING SUPPORT MID/HIGH CLOUDS OVER NORTHERN MANITOBA. THESE CLOUDS ARE ALSO ASSOCIATED WITH A STRONG SHRTWV TROUGH WHICH CAN BE SEEN MOVING ACROSS NORTHERN BRITISH COLUMBIA. && .DISCUSSION... MAIN FORECAST CONCERNS ARE WARM ADVECTION SNOW TONIGHT/FRI AND LES EVENT FOR FRI NIGHT/SAT. TODAY...SHRTWV NEAR WAWA WILL CONTINUE TO MAKE ITS WAY SOUTHWARD IN THE MAINLY NORTHERLY FLOW ALOFT...REACHING SOUTHERN LAKE HURON BY 18Z. AS THIS SHRTWV PASSES...IT WILL CAUSE THE HIGH PRESSURE AREA OVER NW ONTARIO TO BE PULLED DOWN INTO THE CWA BY 00Z. THEREFORE... LES SHOULD BE ON A DIMINISHING TREND. IN FACT...THE LES IS EXPECTED TO END IN THE WESTERN U.P. DUE TO A COMBINATION OF A CRASHING INVERSION AND STRONG DRY AIR ADVECTION...DESPITE LAKE SURFACE TO 850MB DELTA-TS REMAINING AT OR ABOVE 16C. CURRENT LES TRENDS ON WESTERN LAKE SUPERIOR SUPPORT THIS ASSESSMENT TOO. FOR THE NORTH CENTRAL U.P....THE ENDING TREND WILL BE DOMINATED BY THE WIND DIRECTION SINCE DELTA-TS ARE PROGGED AT OR ABOVE 20C AND THE LONGER FETCH OF EASTERN LAKE SUPERIOR WILL MITIGATE THE MOISTURE. HOWEVER...THE LAKE EFFECT WILL NOT BE AS GREAT AS IT WAS YESTERDAY OR LAST NIGHT. WITH 850MB TEMPS REMAINING CHILLY...ONLY WARMING TO -14C WEST OT -20C EAST...WILL CONTINUE TO STAY ON THE LOW END OF GUIDANCE FOR TEMPS. AS FAR AS HEADLINE CHANGES...DROPPED ADVISORY FOR SOUTHERN SCHOOLCRAFT AS LITTLE IN THE WAY OF SNOWFALL APPEARS TO HAVE OCCURRED THERE OVERNIGHT PER RADAR IMAGERY. ALL OTHER HEADLINES WILL CONTINUE TO THEIR EXPIRATION TIMES. TONIGHT...SHRTWV TROUGH CURRENTLY OVER NORTHERN BRITISH COLUMBIA IS PROGGED TO DROP SE TO LAKE WINNIPEG BY 12Z FRI...WITH A 997MB LOW OR SO LOCATED NEAR THE NE END. AS THIS OCCURS...A PORTION OF THE WESTERN RIDGE WILL COME DOWN AHEAD OF THE TROUGH...CAUSING THE HIGH PRESSURE AREA OVER UPPER MICHIGAN TO SLIDE EASTWARD. WARM ADVECTION ON THE BACK SIDE OF THE HIGH/AHEAD OF THE SHRTWV TROUGH...COMBINED WITH UPPER DIVERGENCE ASSOCIATED WITH THE 130KT JET STREAK CURRENTLY IN MANITOBA MOVING TO LAKE HURON...WILL CAUSE A BAND OF MID CLOUDS TO MOVE INTO THE CWA. INITIALLY...DRY LOW LEVELS SHOULD PREVENT PCPN. HOWEVER...CONTINUED ISENTROPIC LIFTING/FRONTOGENETICAL FORCING WILL CAUSE BASES TO LOWER AFTER MIDNIGHT...AND SOME LIGHT SNOW IS EXPECTED TO DEVELOP. THERE STILL REMAINS SOME DISAGREEMENT ON THE DEVELOPMENT OF THIS SNOW...THOUGH...AS NOTED BY NAM SOUNDINGS WHICH SUGGEST THE DRIER LOW LEVELS WILL STAY FIRMLY IN PLACE. GIVEN THIS DISAGREEMENT...AM HESITANT TO GO LIKELY YET...THOUGH WITH THE CONSISTENCY OF THE GFS AND A LOCAL WRF-ARW RUN SHOWING A SIMILAR SCENARIO TO THE GFS...FEEL AN UPGRADE TO 50 POPS IS WARRANTED. TEMPERATURES ARE STILL TRICKY GIVEN THAT THERE WILL BE A FEW HOURS IN THE EVENING WITH ONLY SOME HIGH CLOUDS AROUND. GOING FORECAST MINS LOOK REASONABLE. READINGS SHOULD CLIMB AFTER MIDNIGHT WITH RETURN FLOW AND INCOMING WARM ADVECTION PCPN. FRI...SHRTWV TROUGH WILL CONTINUE MOVING SE...REACHING MINNESOTAS INTERNATIONAL BORDER AROUND 00Z. THE SURFACE LOW ASSOCIATED WITH THE TROUGH IS PROGGED TO MOVE INTO THE WESTERN U.P.. BAND OF WARM ADVECTION SNOW WHICH IS EXPECTED OVER THE WEST HALF OF THE U.P. IN THE MORNING WILL PUSH EAST THROUGH THE DAY...PERHAPS GETTING ENHANCED BY A LAKE MICHIGAN LAKE EFFECT BAND. BEHIND THE WARM ADVECTION SNOW...A DRY SLOT IS PROGGED TO COME IN ALOFT. SOME CONCERN EXISTS THAT THE SNOW MAY TAPER OFF TO FREEZING DRIZZLE...BUT RIGHT NOW THE -10C LAYER STILL REMAIN SATURATED...SO THE SNOW MAY JUST TO TAPER OFF TO FLURRIES OR NOTHING AT ALL. FOR NOW WILL MAINTAIN A CHANCE OF SNOW INTO THE AFTERNOON...BUT HAVE MUCH LOWER QPF VALUES THEN. HAVE RAISED TEMPERATURES SLIGHTLY IN THE WESTERN U.P. GIVEN THAT GUIDANCE HAS WARMED UP IN THIS AREA. OTHERWISE...THE REST OF THE HIGH TEMP FORECAST LOOKS REASONABLE. FRI NIGHT AND SAT...DURING THIS PERIOD...THE SHRTWV TROUGH IS PROGGED BY ALL MODELS TO SWING THROUGH THE CWA. COLD AIR ADVECTION AT 850MB SHOULD ALREADY BE GOING ON FRI EVENING...WITH 850MB TEMPS FALLING TO -12 TO -14C BY 06Z...WHICH SHOULD BE ENOUGH TO GET LAKE EFFECT GOING...ESPECIALLY IN THE WESTERN U.P. GIVEN THE PROGGED WNW LOW LEVEL WIND FLOW. LAKE EFFECT WILL ALSO GET SOME SYNOPTIC SUPPORT DUE TO DPVA AHEAD OF THE SHRTWV TROUGH. HAVE INCLUDED A FEW INCHES OF SNOWFALL...HOWEVER IF THE TROUGH COMES IN FASTER...AT LEAST ADVISORY LEVEL SNOWFALL SHOULD BE MET FOR FRI NIGHT. SINCE IT LOOKS CERTAIN THAT SOME LAKE EFFECT WILL OCCUR IN THE WESTERN U.P....HAVE RAISED POPS TO CATEGORICAL. THINGS GET A LITTLE MORE INTERESTING ON SAT. ON SAT...AS THE SHRTWV TROUGH AND ITS ACCOMPANYING MID-LEVEL MOISTURE MOVES ACROSS...A SECONDARY SURFACE COLD FRONT ASSOCIATED WITH THE SHRTWVS SURFACE LOW IS PROGGED TO DROP SOUTH ACROSS LAKE SUPERIOR. GIVEN THAT 850MB TEMPS COOL A FEW MORE DEGREES C... RESULTING IN PLENTY OF OVER-WATER INSTABILITY...THERE WILL LIKELY BE A SIGNIFICANT CONVERGENT LAKE EFFECT BAND ALONG THE FRONT. WOULD NOT BE SURPRISED TO SEE A COUPLE OF INCHES OF SNOW FALL OUT OF THIS BAND ACROSS ALL OF THE NORTHERN U.P.. GFS FORECAST SOUNDINGS ARE PRETTY IMPRESSIVE WHEN THE BAND COMES THROUGH...INDICATING SATURATED CONDITIONS UP TO 15000 FT AND THE ONLY INVERSION BEING THAT OF THE TROPOPAUSE. IN ADDITION...NORTHERLY WINDS BEHIND THE FRONT...ALONG WITH PLENTY OF LOW TO MID LEVEL MOISTURE AROUND SHOULD SUPPORT MORE INTENSE MULTI-PARALLEL BANDS THAN THOSE TODAY. GIVEN THE CONSISTENCY FROM THE MODELS PREDICTING THIS EVENT...HAVE INCREASED POPS TO CATEGORICAL. IN FACT...HAVE EVEN INCLUDED THE WORDING OF HEAVY AT TIMES FOR THE FAR WESTERN U.P. AS THIS AREA WILL SEE STRONG LOW LEVEL CONVERGENCE ALL DAY. HAVE ADJUSTED QPF/SNOW AMOUNTS UPWARD TO NEAR WARNING CRITERIA FOR THE FAR WESTERN U.P. WITH THE REST OF THE NORTHERN U.P. AT ADVISORY LEVEL. FOR NOW...THE EVENT WILL CONTINUE TO BE HIGHLIGHTED IN THE HWO...BUT FUTURE SHIFTS WILL LIKELY NEED TO ISSUE WATCHES...WARNINGS AND/OR ADVISORIES. SAT NIGHT AND SUN...GFS/UKMET/ECMWF INDICATE THAT AFTER THE PASSAGE OF SATURDAYS SHRTWV TROUGH...ANOTHER SHRTWV WILL DIVE SOUTHWARD THROUGH MINNESOTA AND INTO ILLINOIS. MOISTURE ASSOCIATED WITH THIS SHRTWV LOOKS TO STAY TO THE WEST OF HERE...THEREFORE WITH 850MB TEMPS COOLING INTO THE LOW -20S C...DRY AIR ADVECTION AND LOWERING INVERSIONS...THE LAKE EFFECT SNOW WILL BE ON A DIMINISHING TREND THROUGH THIS PERIOD. OTHERWISE...WITH THE COOLER 850MB TEMPS...READINGS WHICH WILL BE CLOSE TO NORMAL FOR FRI AND SAT WILL GO BACK TO BELOW NORMAL. BEYOND SUN...LOOKS LIKE THE PATTERN WILL REMAIN COLD WITH PERIODS OF LAKE EFFECT SNOW. LOOKING FARTHER OUT TOWARDS THE BEGINNING OF FEBRUARY...THERE HAS BEEN A LOT OF CONSISTENCY WITH PAST GFS AND ECMWF RUNS...INCLUDING THOSE TODAY...SUGGESTING A COLDER ARCTIC AIRMASS TO MOVE INTO THE CWA WITH 850MB TEMPS AROUND THE -30C MARK. WILL WAIT AND SEE IF THIS OCCURS...BUT GIVEN THE CONSISTENCY...IT BEARS WATCHING. COORD WITH GRB AND HPC...THANKS. AJ && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FOR MIZ006 UNTIL 22Z. LAKE EFFECT SNOW ADVISORY FOR MIZ005-013 UNTIL 18Z. LAKE EFFECT SNOW ADVISORY FOR MIZ002-009 UNTIL 12Z. LAKE EFFECT SNOW ADVISORY FOR MIZ085 UNTIL 22Z. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 404 AM EST THU JAN 25 2007 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED RIDGING FROM SOUTHERN CALIFORNIA INTO NORTHERN ALBERTA WHILE UPPER TROUGHING DOMINATED SE CANADA INTO THE GREAT LAKES. WITHIN THIS TROUGH...A SHRTWV CAN BE SEEN DIVING SOUTHWARD THROUGH NORTHERN ONTARIO...NOW NEAR WAWA. 850MB TEMPS ASSOCIATED WITH THIS SHRTWV APPEAR TO BE AROUND -25C BASED ON 00Z RAOBS FROM MOOSONEE AND PICKLE LAKE. ALTHOUGH THE AIR IS QUITE COLD WITH THE SHRTWV...VERY LITTLE IS OCCURRING ON IR IMAGERY WITH IT DUE TO THE PRESENCE OF VERY DRY AIR (PRECIPITABLE WATER OF 0.04 INCHES ON THE PICKLE LAKE SOUNDING). SURFACE TEMPERATURES AND DEWPOINTS ALSO DEPICT THE SAME STORY OVER NORTHERN ONTARIO...WITH READINGS WELL BELOW ZERO F. THE COLD AND DRY AIR CONTINUES TO FLOW ACROSS LAKE SUPERIOR ON NORTHERLY WINDS BETWEEN A 1032MB HIGH OVER NW ONTARIO AND A LOW PRESSURE TROUGH THAT EXTENDS FROM LAKE ERIE TO SOUTHERN WISCONSIN. A LAKE INDUCED TROUGH ALSO EXTENDS FROM LAKE ERIE NW TO NEAR ONTONAGON. PLENTY OF LAKE EFFECT SNOW SHOWERS EXIST DUE TO THE COLD AIR FLOWING OVER 2-3C WATER TEMPS. CURRENT RADAR IMAGERY SHOWS A FEW DISORGANIZED BANDS IN ALGER AND EASTERN MARQUETTE COUNTIES...THOUGH THERE ARE A FEW 28DBZ PIXELS WITHIN THEM. THERE WERE ALSO SOME INTENSE BANDS OCCURRING IN THE FAR WESTERN U.P. OVERNIGHT...WITH THE BESSEMER AREA PICKING UP AROUND 6 INCHES SINCE 7 PM CST PER THE COUNTY SHERIFF. HOWEVER... OVER THE PAST FEW HOURS...THE SATELLITE APPEARANCE HAS GREATLY DIMINISHED FOR THE LAKE EFFECT BANDS ON WESTERN LAKE SUPERIOR. TO OUR NW...A 130 KT JET STREAK IS MOVING THROUGH WESTERN ONTARIO. UPPER DIVERGENCE IN THE RIGHT ENTRANCE REGION IS HELPING SUPPORT MID/HIGH CLOUDS OVER NORTHERN MANITOBA. THESE CLOUDS ARE ALSO ASSOCIATED WITH A STRONG SHRTWV TROUGH WHICH CAN BE SEEN MOVING ACROSS NORTHERN BRITISH COLUMBIA. && .DISCUSSION... MAIN FORECAST CONCERNS ARE WARM ADVECTION SNOW TONIGHT/FRI AND LES EVENT FOR FRI NIGHT/SAT. TODAY...SHRTWV NEAR WAWA WILL CONTINUE TO MAKE ITS WAY SOUTHWARD IN THE MAINLY NORTHERLY FLOW ALOFT...REACHING SOUTHERN LAKE HURON BY 18Z. AS THIS SHRTWV PASSES...IT WILL CAUSE THE HIGH PRESSURE AREA OVER NW ONTARIO TO BE PULLED DOWN INTO THE CWA BY 00Z. THEREFORE... LES SHOULD BE ON A DIMINISHING TREND. IN FACT...THE LES IS EXPECTED TO END IN THE WESTERN U.P. DUE TO A COMBINATION OF A CRASHING INVERSION AND STRONG DRY AIR ADVECTION...DESPITE LAKE SURFACE TO 850MB DELTA-TS REMAINING AT OR ABOVE 16C. CURRENT LES TRENDS ON WESTERN LAKE SUPERIOR SUPPORT THIS ASSESSMENT TOO. FOR THE NORTH CENTRAL U.P....THE ENDING TREND WILL BE DOMINATED BY THE WIND DIRECTION SINCE DELTA-TS ARE PROGGED AT OR ABOVE 20C AND THE LONGER FETCH OF EASTERN LAKE SUPERIOR WILL MITIGATE THE MOISTURE. HOWEVER...THE LAKE EFFECT WILL NOT BE AS GREAT AS IT WAS YESTERDAY OR LAST NIGHT. WITH 850MB TEMPS REMAINING CHILLY...ONLY WARMING TO -14C WEST OT -20C EAST...WILL CONTINUE TO STAY ON THE LOW END OF GUIDANCE FOR TEMPS. AS FAR AS HEADLINE CHANGES...DROPPED ADVISORY FOR SOUTHERN SCHOOLCRAFT AS LITTLE IN THE WAY OF SNOWFALL APPEARS TO HAVE OCCURRED THERE OVERNIGHT PER RADAR IMAGERY. ALL OTHER HEADLINES WILL CONTINUE TO THEIR EXPIRATION TIMES. TONIGHT...SHRTWV TROUGH CURRENTLY OVER NORTHERN BRITISH COLUMBIA IS PROGGED TO DROP SE TO LAKE WINNIPEG BY 12Z FRI...WITH A 997MB LOW OR SO LOCATED NEAR THE NE END. AS THIS OCCURS...A PORTION OF THE WESTERN RIDGE WILL COME DOWN AHEAD OF THE TROUGH...CAUSING THE HIGH PRESSURE AREA OVER UPPER MICHIGAN TO SLIDE EASTWARD. WARM ADVECTION ON THE BACK SIDE OF THE HIGH/AHEAD OF THE SHRTWV TROUGH...COMBINED WITH UPPER DIVERGENCE ASSOCIATED WITH THE 130KT JET STREAK CURRENTLY IN MANITOBA MOVING TO LAKE HURON...WILL CAUSE A BAND OF MID CLOUDS TO MOVE INTO THE CWA. INITIALLY...DRY LOW LEVELS SHOULD PREVENT PCPN. HOWEVER...CONTINUED ISENTROPIC LIFTING/FRONTOGENETICAL FORCING WILL CAUSE BASES TO LOWER AFTER MIDNIGHT...AND SOME LIGHT SNOW IS EXPECTED TO DEVELOP. THERE STILL REMAINS SOME DISAGREEMENT ON THE DEVELOPMENT OF THIS SNOW...THOUGH...AS NOTED BY NAM SOUNDINGS WHICH SUGGEST THE DRIER LOW LEVELS WILL STAY FIRMLY IN PLACE. GIVEN THIS DISAGREEMENT...AM HESITANT TO GO LIKELY YET...THOUGH WITH THE CONSISTENCY OF THE GFS AND A LOCAL WRF-ARW RUN SHOWING A SIMILAR SCENARIO TO THE GFS...FEEL AN UPGRADE TO 50 POPS IS WARRANTED. TEMPERATURES ARE STILL TRICKY GIVEN THAT THERE WILL BE A FEW HOURS IN THE EVENING WITH ONLY SOME HIGH CLOUDS AROUND. GOING FORECAST MINS LOOK REASONABLE. READINGS SHOULD CLIMB AFTER MIDNIGHT WITH RETURN FLOW AND INCOMING WARM ADVECTION PCPN. FRI...SHRTWV TROUGH WILL CONTINUE MOVING SE...REACHING MINNESOTAS INTERNATIONAL BORDER AROUND 00Z. THE SURFACE LOW ASSOCIATED WITH THE TROUGH IS PROGGED TO MOVE INTO THE WESTERN U.P.. BAND OF WARM ADVECTION SNOW WHICH IS EXPECTED OVER THE WEST HALF OF THE U.P. IN THE MORNING WILL PUSH EAST THROUGH THE DAY...PERHAPS GETTING ENHANCED BY A LAKE MICHIGAN LAKE EFFECT BAND. BEHIND THE WARM ADVECTION SNOW...A DRY SLOT IS PROGGED TO COME IN ALOFT. SOME CONCERN EXISTS THAT THE SNOW MAY TAPER OFF TO FREEZING DRIZZLE...BUT RIGHT NOW THE -10C LAYER STILL REMAIN SATURATED...SO THE SNOW MAY JUST TO TAPER OFF TO FLURRIES OR NOTHING AT ALL. FOR NOW WILL MAINTAIN A CHANCE OF SNOW INTO THE AFTERNOON...BUT HAVE MUCH LOWER QPF VALUES THEN. HAVE RAISED TEMPERATURES SLIGHTLY IN THE WESTERN U.P. GIVEN THAT GUIDANCE HAS WARMED UP IN THIS AREA. OTHERWISE...THE REST OF THE HIGH TEMP FORECAST LOOKS REASONABLE. FRI NIGHT AND SAT...DURING THIS PERIOD...THE SHRTWV TROUGH IS PROGGED BY ALL MODELS TO SWING THROUGH THE CWA. COLD AIR ADVECTION AT 850MB SHOULD ALREADY BE GOING ON FRI EVENING...WITH 850MB TEMPS FALLING TO -12 TO -14C BY 06Z...WHICH SHOULD BE ENOUGH TO GET LAKE EFFECT GOING...ESPECIALLY IN THE WESTERN U.P. GIVEN THE PROGGED WNW LOW LEVEL WIND FLOW. LAKE EFFECT WILL ALSO GET SOME SYNOPTIC SUPPORT DUE TO DPVA AHEAD OF THE SHRTWV TROUGH. HAVE INCLUDED A FEW INCHES OF SNOWFALL...HOWEVER IF THE TROUGH COMES IN FASTER...AT LEAST ADVISORY LEVEL SNOWFALL SHOULD BE MET FOR FRI NIGHT. SINCE IT LOOKS CERTAIN THAT SOME LAKE EFFECT WILL OCCUR IN THE WESTERN U.P....HAVE RAISED POPS TO CATEGORICAL. THINGS GET A LITTLE MORE INTERESTING ON SAT. ON SAT...AS THE SHRTWV TROUGH AND ITS ACCOMPANYING MID-LEVEL MOISTURE MOVES ACROSS...A SECONDARY SURFACE COLD FRONT ASSOCIATED WITH THE SHRTWVS SURFACE LOW IS PROGGED TO DROP SOUTH ACROSS LAKE SUPERIOR. GIVEN THAT 850MB TEMPS COOL A FEW MORE DEGREES C... RESULTING IN PLENTY OF OVER-WATER INSTABILITY...THERE WILL LIKELY BE A SIGNIFICANT CONVERGENT LAKE EFFECT BAND ALONG THE FRONT. WOULD NOT BE SURPRISED TO SEE A COUPLE OF INCHES OF SNOW FALL OUT OF THIS BAND ACROSS ALL OF THE NORTHERN U.P.. GFS FORECAST SOUNDINGS ARE PRETTY IMPRESSIVE WHEN THE BAND COMES THROUGH...INDICATING SATURATED CONDITIONS UP TO 15000 FT AND THE ONLY INVERSION BEING THAT OF THE TROPOPAUSE. IN ADDITION...NORTHERLY WINDS BEHIND THE FRONT...ALONG WITH PLENTY OF LOW TO MID LEVEL MOISTURE AROUND SHOULD SUPPORT MORE INTENSE MULTI-PARALLEL BANDS THAN THOSE TODAY. GIVEN THE CONSISTENCY FROM THE MODELS PREDICTING THIS EVENT...HAVE INCREASED POPS TO CATEGORICAL. IN FACT...HAVE EVEN INCLUDED THE WORDING OF HEAVY AT TIMES FOR THE FAR WESTERN U.P. AS THIS AREA WILL SEE STRONG LOW LEVEL CONVERGENCE ALL DAY. HAVE ADJUSTED QPF/SNOW AMOUNTS UPWARD TO NEAR WARNING CRITERIA FOR THE FAR WESTERN U.P. WITH THE REST OF THE NORTHERN U.P. AT ADVISORY LEVEL. FOR NOW...THE EVENT WILL CONTINUE TO BE HIGHLIGHTED IN THE HWO...BUT FUTURE SHIFTS WILL LIKELY NEED TO ISSUE WATCHES...WARNINGS AND/OR ADVISORIES. SAT NIGHT AND SUN...GFS/UKMET/ECMWF INDICATE THAT AFTER THE PASSAGE OF SATURDAYS SHRTWV TROUGH...ANOTHER SHRTWV WILL DIVE SOUTHWARD THROUGH MINNESOTA AND INTO ILLINOIS. MOISTURE ASSOCIATED WITH THIS SHRTWV LOOKS TO STAY TO THE WEST OF HERE...THEREFORE WITH 850MB TEMPS COOLING INTO THE LOW -20S C...DRY AIR ADVECTION AND LOWERING INVERSIONS...THE LAKE EFFECT SNOW WILL BE ON A DIMINISHING TREND THROUGH THIS PERIOD. OTHERWISE...WITH THE COOLER 850MB TEMPS...READINGS WHICH WILL BE CLOSE TO NORMAL FOR FRI AND SAT WILL GO BACK TO BELOW NORMAL. BEYOND SUN...LOOKS LIKE THE PATTERN WILL REMAIN COLD WITH PERIODS OF LAKE EFFECT SNOW. LOOKING FARTHER OUT TOWARDS THE BEGINNING OF FEBRUARY...THERE HAS BEEN A LOT OF CONSISTENCY WITH PAST GFS AND ECMWF RUNS...INCLUDING THOSE TODAY...SUGGESTING A COLDER ARCTIC AIRMASS TO MOVE INTO THE CWA WITH 850MB TEMPS AROUND THE -30C MARK. WILL WAIT AND SEE IF THIS OCCURS...BUT GIVEN THE CONSISTENCY...IT BEARS WATCHING. COORD WITH GRB AND HPC...THANKS. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING FOR MIZ006 UNTIL 22Z. LAKE EFFECT SNOW ADVISORY FOR MIZ005-013 UNTIL 18Z. LAKE EFFECT SNOW ADVISORY FOR MIZ002-009 UNTIL 12Z. LAKE EFFECT SNOW ADVISORY FOR MIZ085 UNTIL 22Z. && $$ AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 936 PM CST FRI JAN 26 2007 .UPDATE... MADE SOME FAIRLY MAJOR ADJUSTMENTS TO THE SKY GRIDS TONIGHT AND INTO ERY SAT...PRIMARILY DUE TO THE LACK OF CLOUD DVLPMNT DURG THE EVE ALG OR BHND THE FNT. ALTHO SM LWR CLD DVLPMT MAY STILL OCR OVRNGT ACR THE N... MAIN CLOUD EMPHASIS SHOULD COME FROM MOISTURE STREAMING NE FROM SYS OVER THE SW U.S...WITH CLDS OVERSPREADING S HALF OF FA DURG THE PREDAWN HRS. ALTHO WE ARE STILL QUITE MILD AT 03Z DIDN`T CHANGE MIN TEMPS TOO MUCH...AS WE EXPECT THAT THE LO TEMP WL OCR IN THE 13-15Z TIME FRAME. FOR SAT...CLDS ASSOC WITH SYS IN S BRANCH OF WESTERLIES SHUD CONT TO AFFECT S PARTS OF FA...WHILE CU/SC SHUD BE ON THE INCR OVR N AREAS AS SCNDRY CDFNT AND ASSOC LO LVL MOISTURE DROPS INTO AREA. TRUETT && .DISCUSSION... RIDGE OF HIGH PRESSURE HAS MOVED OFF TO OUR SE ALLOWING SOUTHWESTERLY WINDS TO RETURN TO THE REGION TODAY. AS A RESULT... TEMPS HAVE WARMED UP INTO THE UPPER 40S TO UPPER 50S AS OF 20Z. IN THE MEANTIME...A COLD FRONT EXTENDED FROM SFC LOW OVER NRN WI THRU IA THEN INTO SWRN KS. THIS WILL BE OUR NEXT WEATHER MAKER...WITH MAIN AFFECT BEING CLOUDS...MUCH COLDER TEMPS AND SOME FLURRIES/SPRINKLES. FOR TONIGHT...FRONT WILL MOVE INTO NORTHERN PTNS OF AREA BY 05Z... THEN SLIDE SE EXITING CWA BY 14Z. AS FRONT APPROACHES AREA...LOW LEVEL MOISTURE WILL BE ON THE INCREASE. THAT IN CONJUNCTION WITH SOME LIFT ALONG BOUNDARY...WILL SEE CLOUDS DEVELOP AS THE EVENING PROGRESSES. BECAUSE OF THE SWRLY WINDS AHEAD OF FRONT AND INCREASING CLOUDS...ONLY EXPECT LOW TEMPS IN THE MID 20S N TO MID 30S S. ON SATURDAY...AS COLDER AIR MAKES ITS WAY INTO AREA ALONG WITH THICKENING AND LOWERING CLOUDS...EXPECT SOME FLURRY/SPRINKLE ACTIVITY TO DEVELOP. HIGH TEMPS WILL ONLY BE ABOUT 5 DEGREES WARMER THAN TONIGHT/S LOWS...FROM AROUND 30 N TO AROUND 40 FAR S. THE ARCTIC AIR REALLY SINKS SOUTH OVER REGION LATE SATURDAY AFTERNOON AND INTO THE OVERNIGHT HOURS...POSSIBLY GIVING US SOME OF OUR COLDEST WEATHER YET. HOWEVER...THE LINGERING CLOUDS WILL KEEP TEMPS FROM FALLING TOO MUCH. WILL SEE LOWS AROUND 10 N TO UPPER TEENS FAR S WITH SOME FLURRIES. ON SUNDAY...WILL BEGIN TO SEE SOME CLEARING AS SFC RIDGE BUILDS IN...BUT TEMPS WILL STRUGGLE TO REACH THE UPPER TEENS TO MID 20S. BEYOND THAT...EXTENDED FORECAST CONTINUES SEE SAW PATTERN WITH SYSTEMS AFFECTING REGION ABOUT EVERY OTHER DAY. NEXT CHANCE FOR SOME FLURRIES ON MONDAY...THEN AGAIN ON WED AFTERNOON THRU THU NIGHT. BYRD && .AVIATION... FOR THE 00Z TAFS...CDFNT EXTDG FM SFC LOW OVR WI SW THRU NWRN MO OK PNHDL WL MOV SEWD THRU THE CWA TGT. CDFNT SHOULD MOVR THRU UIN ARND 03Z...COU 05-06Z...AND STL AND SUS FM 07-08Z. SFC WNDS WILL VEER ARND TO A NWLY DIRECTION BHND CDFNT. RUC AND GFS MDLS FCST AT LEAST A BAND OF POST FRONTAL STRATUS OR STRATOCUMULUS CLOUDS DVLPG AND MOVG SEWD THRU THE CWA LTR TGT INTO SAT. GFS MDL TIME HGT SECTION OF RH FOR STL SHOW INCRSG MOISTURE BLW 850 MB THIS EVNG. CLOUD CEILING SHOULD SLOWLY RISE ON SAT BASED ON GFS MOS CIG HEIGHT GUIDANCE AND RH TIME HGT PROFILE. NWLY SFC WNDS SHOULD BCM RELATIVELY STG AND GUSTY BY SAT AFTN. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 611 PM CST FRI JAN 26 2007 .DISCUSSION... RIDGE OF HIGH PRESSURE HAS MOVED OFF TO OUR SE ALLOWING SOUTHWESTERLY WINDS TO RETURN TO THE REGION TODAY. AS A RESULT... TEMPS HAVE WARMED UP INTO THE UPPER 40S TO UPPER 50S AS OF 20Z. IN THE MEANTIME...A COLD FRONT EXTENDED FROM SFC LOW OVER NRN WI THRU IA THEN INTO SWRN KS. THIS WILL BE OUR NEXT WEATHER MAKER...WITH MAIN AFFECT BEING CLOUDS...MUCH COLDER TEMPS AND SOME FLURRIES/SPRINKLES. FOR TONIGHT...FRONT WILL MOVE INTO NORTHERN PTNS OF AREA BY 05Z... THEN SLIDE SE EXITING CWA BY 14Z. AS FRONT APPROACHES AREA...LOW LEVEL MOISTURE WILL BE ON THE INCREASE. THAT IN CONJUNCTION WITH SOME LIFT ALONG BOUNDARY...WILL SEE CLOUDS DEVELOP AS THE EVENING PROGRESSES. BECAUSE OF THE SWRLY WINDS AHEAD OF FRONT AND INCREASING CLOUDS...ONLY EXPECT LOW TEMPS IN THE MID 20S N TO MID 30S S. ON SATURDAY...AS COLDER AIR MAKES ITS WAY INTO AREA ALONG WITH THICKENING AND LOWERING CLOUDS...EXPECT SOME FLURRY/SPRINKLE ACTIVITY TO DEVELOP. HIGH TEMPS WILL ONLY BE ABOUT 5 DEGREES WARMER THAN TONIGHT/S LOWS...FROM AROUND 30 N TO AROUND 40 FAR S. THE ARCTIC AIR REALLY SINKS SOUTH OVER REGION LATE SATURDAY AFTERNOON AND INTO THE OVERNIGHT HOURS...POSSIBLY GIVING US SOME OF OUR COLDEST WEATHER YET. HOWEVER...THE LINGERING CLOUDS WILL KEEP TEMPS FROM FALLING TOO MUCH. WILL SEE LOWS AROUND 10 N TO UPPER TEENS FAR S WITH SOME FLURRIES. ON SUNDAY...WILL BEGIN TO SEE SOME CLEARING AS SFC RIDGE BUILDS IN...BUT TEMPS WILL STRUGGLE TO REACH THE UPPER TEENS TO MID 20S. BEYOND THAT...EXTENDED FORECAST CONTINUES SEE SAW PATTERN WITH SYSTEMS AFFECTING REGION ABOUT EVERY OTHER DAY. NEXT CHANCE FOR SOME FLURRIES ON MONDAY...THEN AGAIN ON WED AFTERNOON THRU THU NIGHT. BYRD && .AVIATION... FOR THE 00Z TAFS...CDFNT EXTDG FM SFC LOW OVR WI SW THRU NWRN MO OK PNHDL WL MOV SEWD THRU THE CWA TGT. CDFNT SHOULD MOVR THRU UIN ARND 03Z...COU 05-06Z...AND STL AND SUS FM 07-08Z. SFC WNDS WILL VEER ARND TO A NWLY DIRECTION BHND CDFNT. RUC AND GFS MDLS FCST AT LEAST A BAND OF POST FRONTAL STRATUS OR STRATOCUMULUS CLOUDS DVLPG AND MOVG SEWD THRU THE CWA LTR TGT INTO SAT. GFS MDL TIME HGT SECTION OF RH FOR STL SHOW INCRSG MOISTURE BLW 850 MB THIS EVNG. CLOUD CEILING SHOULD SLOWLY RISE ON SAT BASED ON GFS MOS CIG HEIGHT GUIDANCE AND RH TIME HGT PROFILE. NWLY SFC WNDS SHOULD BCM RELATIVELY STG AND GUSTY BY SAT AFTN. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ST LOUIS MO 615 AM CST THU JAN 25 2007 .DISCUSSION... STRATUS CLOUDINESS ACRS THE CWA ATTM ALTHOUGH THERE IS A LARGE AREA OF CLEARING OVR ERN IA AND NRN IL WHERE LOW SFC DWPTS HAVE ADVCTD SWD INTO THE AREA BHND A WK CDFNT/SFC TROF. RUC RH FCSTS INDICATE THIS MAY BRING SOME CLEARING TO THE ERN PTN OF THE CWA THIS MRNG. MUCH OF WRN MO HAS ALSO CLEARED OUT FM THE STRATUS DECK...ALTHOUGH THERE IS STILL MOVE STRATUS CLOUD CVR OVR IA POISED TO DROP SEWD INTO THE CWA PLUS SOME MID LVL CLOUDINESS OVR ERN NEBRASKA AND WRN IA WHICH SHOULD MOVE SEWD THRU WRN MO THIS MRNG. ALTHOUGH THERE IS PLENTY OF UNCERTAINTY AND COMPLEXITY IN THE CLOUD FCST TDA WILL LIKELY FOLLOW MDL GUIDANCE WHICH INDICATES DCRSG LOW LVL RH TDA AND DCRSG CLOUDINESS WITH AT LEAST PARTIAL SUNSHINE EXPECTED THIS AFTN. SHOULD BE PRETTY GOOD SUBSIDENCE THIS AFTN WITH RELATIVELY STG SFC RDG BLDG SEWD INTO THE CWA. EVEN WITH SOME SUNSHINE LTR TDA DO NOT SEE MUCH OF A DIURNAL RISE IN TEMPS WITH NAM MDL INDICATING STG 850 MB CAA DURING THE MRNG. MDLS SHOWING A RELATIVELY STG 850 MB TEMP GRADIENT ACRS THE CWA WITH -8 TO -10 DGRS C OVR THE NERN PTN OF THE CWA TO -2 TO -4 DGRS C OVR THE SWRN PTN OF THE CWA AT 18Z THU. MAY GO A TAD ABV MOS GUIDANCE TEMPS TDA THOUGH AS INITIAL MOS GUIDANCE TEMPS ARE ALREADY TOO COOL. SHOULD HAVE GOOD RADIATIONAL COOLING OVR THE SERN PTN OF THE CWA TGT UNDERNEATH SFC RDG AXIS. SFC TEMPS MAY ACTUALLY BCM NRLY STEADY OVR THE NRN AND WRN PTN OF THE CWA LT TGT AS MDLS...ESPECIALLY THE NAM INDICATES STG LOW LVL WAA OVR THE NRN PTN OF THE CWA LT TGT. SFC WNDS WILL ALSO BCM SWLY OVR THE NRN AND WRN PTN OF THE CWA LT TGT ON THE BACKSIDE OF THE SFC RDG. FRI LOOKS TO BE QUITE WRM AS WLY 850 MB WNDS BRING WRM AIR INTO THE CWA WITH MDL 850 MB TEMPS RANGING FM 3-4 DGRS C OVR THE SERN PTN OF THE CWA TO ARND 7 DGRS C OVR THE NWRN PTN OF THE CWA AT 18Z FRI. THERE SHOULD ALSO BE PLENTY OF SOLAR INSOLATION. THIS WRM WX WILL BE SHORT LIVED THOUGH AS MDLS BRING A STG CDFNT SEWD THRU THE CWA FRI NGT. DO NOT SEE MUCH UPR LVL FRCG FOR PCPN FRI NGT AND MOISTURE APRS SHALLOW BLW 850 MB. MAY INCLUDE A LOW POP FOR LGT RAIN/SNOW FRI NGT WITH THE GFS MDL DEPICTING A VRY LGT BAND OF PCPN ALNG AND JUST BHND CDFNT. LOOKING AT MDL FCST SOUNDINGS MAY BE JUST NON MEASUREABLE DRIZZLE/FREEZING FRIZZLE OR FLURRIES JUST BHND CDFNT. A STG SRN STREAM VORT MAX MAY KEEP POST FRONTAL PCPN GOING OVR THE SRN PTN OF THE CWA THRU SAT...ALTHOUGH IT APRS THAT MOST OF THE PCPN ASSOCIATED WITH THIS FEATURE WILL REMAIN S OF THE CWA. MAY ALSO BE FLURRIES OR SNOW SHOWERS OVR THE NRN PTN OF THE CWA ON SAT AFTN INTO SAT NGT AS NRN STREAM VORT MAX...SHEAR AXIS MOVES SEWD INTO THE CWA. MORE SIGNIFICANT MAY BE MUCH COLDER AIR DROPPING SWD THRU THE CWA SAT AND SAT NGT WITH THE GFS MDL BRINGING THE -16 DGR C 850 MB ISOTHERM DOWN TO STL BY 12Z SUN. GKS && .AVIATION... FOR THE 12Z TAFS...MVFR CLOUD COVERAGE IS GOING TO BOUNCE AROUND A BIT TODAY. THERE IS A 70 MILE WIDE BAND OF CLOUDS ALONG AND WEST OF THE MISSISSIPPI RIVER. WINDS AT CLOUD LEVELS ARE FROM AROUND 340 DEGREES SO THERE IS A SLIGHT SOUTHWARD DRIFT OF THE CLEARING LINE. THIS PASSED QUINCY ABOUT 11Z AND SHOULD CLEAR AT KSTL BY SUNRISE AND AT KSUS BY 14Z. COLUMBIA IS IN A SUCKER HOLE FOR ABOUT 3 HOURS BUT ANOTHER BATCH OF LOW CLOUDS IN NORTHERN MISSOURI WILL PROBABLY SLIDE SOUTHEAST BACK INTO COLUMBIA. THE MODELS DO NOT BRING THIS BACK...THEY CLEAR SKIES AND MOVE ANY CLOUDS TO THE EAST OF THE AREA. THIS REMAINS TO BE SEEN. THINGS SHOULD EVENTUALLY BE FINE THOUGH AND LOOKING FOR CLEAR SKIES TONIGHT. PEDIGO && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 330 PM CST THU JAN 25 2007 .SHORT TERM...TONIGHT THROUGH 12Z SUNDAY. MAIN CHALLENGES INVOLVE TIMING OF COLD FRONT TOMORROW AND ASSOCIATED EFFECT ON TEMPERATURES...AND POSSIBILITY OF A FEW FLURRIES ON SATURDAY. AFTERNOON WATER VAPOR IMAGERY IN COMBINATION WITH RUC UPPER AIR ANALYSIS DATA SHOWS STRONG UPPER RIDGING CENTERED OVER THE ROCKIES...WITH A NORTHWEST FLOW DOWNSTREAM OVER THE PLAINS. MEANWHILE OBJECTIVE SURFACE ANALYSIS SHOWS A WEAK TROUGH EXTENDING THROUGH THE CWA...RESULTING IN LIGHT WINDS. FOG ACROSS THE FAR NORTHEAST HAS BEEN SLOW TO ERODE THROUGH THE DAY...BUT THE WESTERN EDGE HAS FINALLY PUSHED OUT OF THE CWA. SUNSHINE ACROSS THE AREA HAS HELPED TEMPS WARM GENERALLY INTO THE UPPER 30S TO LOWER 40S DESPITE LIMITED MIXING. THE MAIN QUESTION FOR TONIGHT IS WHETHER ANY FOG WILL BE ABLE TO REDEVELOP. MODELS CONTINUE TO PUSH THE ENHANCED LOW-LEVEL RH VALUES EAST AWAY FROM THE CWA...SUGGESTING IT WILL NOT. DESPITE THIS...BELIEVE WE MAY SEE AT LEAST SOME PATCHY DEVELOPMENT ACROSS THE EAST. SURFACE WINDS TURN INCREASINGLY SOUTHWEST THROUGH THE NIGHT. HOWEVER...WINDS ARE SLOW TO TAKE ON THE WESTERLY COMPONENT ACROSS THE EAST AND WITH LINGERING FOG JUST TO OUR EAST/NORTHEAST...BELIEVE IT COULD SNEAK BACK INTO EASTERN AREAS THIS EVENING. IF FOG DOES INDEED FORM...IT MAY VERY WELL DISSIPATE/PUSH EAST ONCE THE SOUTHWEST WINDS TAKE HOLD LATER TONIGHT. WARM AIR ADVECTION ON SOUTHWEST WINDS WILL KEEP MIN TEMPS TONIGHT ON THE MILD SIDE FOR THIS TIME OF THE YEAR. AN UPPER LOW DIVING THROUGH SOUTH CENTRAL CANADA STARTS TO KNOCK THE UPPER RIDGE DOWN TONIGHT INTO TOMORROW...AND SENDS A COLD FRONT SOUTH THROUGH THE PLAINS. IT LOOKS LIKE THE FRONT WILL MAKE IT INTO THE NORTHWEST CWA BY 18Z AND THEN PUSH SOUTH ACROSS THE REST OF THE AREA DURING THE AFTERNOON. THE FRONT IS ON PACE TO ARRIVE LATE ENOUGH THAT WE SHOULD SEE ONE MORE MILD DAY WITH HIGHS IN THE 40S. A FAIRLY WARM START TO THE DAY...ENHANCED MIXING...AND PLENTY OF INSOLATION WILL ALL ACT IN FAVOR OF THE WARMING. THE FRONT WILL BE SEVERELY MOISTURE STARVED...AND HENCE NO PRECIPITATION IS EXPECTED WITH ITS PASSAGE. COLD AIR ADVECTION BEHIND THE FRONT WILL KNOCK TEMPS BACK INTO THE TEENS FRIDAY NIGHT. STRONG COLD AIR ADVECTION CONTINUES ON SATURDAY WITH H85 TEMPS FALLING TO AROUND -15C. THIS WILL RESULT IN MAX TEMPS ROUGHLY 15 TO 20 DEGREES COLDER THAN THOSE EXPECTED TOMORROW. PRECIP CHANCES LOOK VERY MINIMAL WITH THIS SYSTEM...BUT DID INCLUDE FLURRIES ACROSS THE EAST/NORTHEAST SATURDAY AFTERNOON AND EVENING. FORECAST SOUNDINGS AND CROSS SECTIONS SHOW A LITTLE THICKER STRATUS DECK ACROSS THE EAST...AND THIS DECK WILL BE IN THE DENDRITIC LAYER GIVEN THE COLD AIRMASS IN PLACE. AS THE TAIL END OF THE UPPER WAVE SWINGS ACROSS THIS PART OF THE CWA...IT MAY PROVIDE ENOUGH FORCING TO SQUEEZE OUT A FEW FLURRIES. SATURDAY NIGHT WILL BE QUITE COLD AS A 1030+ MB SURFACE HIGH SLIPS SOUTH INTO THE REGION...WITH LOWS FALLING INTO THE SINGLE DIGITS ACROSS MOST LOCATIONS. .LONG TERM...12Z SUNDAY THROUGH THURSDAY. MAIN PROBLEM SURROUNDS ARCTIC AIR SURGES. MEDIUM RANGE MODELS ARE IN GENERAL AGREEMENT THAT MUCH OF THE EXTENDED PERIOD WILL BE DOMINATED WITH ARCTIC AIR. THE PERIOD STARTS OFF WITH ARCTIC AIR IN PLACE ALREADY ON SUNDAY. SOME MODIFICATION TO THE LOW LEVEL COLD AIR TRIES TO TAKE PLACE SUNDAY NIGHT...HOWEVER THE NEXT REINFORCING SHOT OF COLD AIR ARRIVES AGAIN ON MONDAY AS A WAVE DIVES SOUTH IN THE UPPER FLOW. THIS GENERAL SCENARIO OCCURS AGAIN TUESDAY NIGHT INTO WEDNESDAY. THE BOTTOM LINE IS MUCH OF NEXT WEEK SHOULD BE BELOW NORMAL WITH RESPECT TO TEMPERATURES. HAVE CUT NUMERICAL GUIDANCE VALUES THROUGH MOST OF THE EXTENDED FORECAST PERIOD. PRECIPITATION CHANCES THROUGH THE PERIOD LOOK RATHER MEAGER WITH LIMITED MOISTURE ASSOCIATED WITH THE FRONTAL/UPPER WAVE PASSAGES. THE ONLY PERIOD THAT IS MORE QUESTIONABLE APPEARS TO BE WEDNESDAY SINCE SLIGHTLY BETTER MOISTURE IS AVAILABLE...AND THE UPPER LEVEL SUPPORT IS A BIT STRONGER TOO. HPC GUIDANCE POPS ARE NEAR 30 PERCENT...AND AFTER COLLABORATION WITH SURROUNDING OFFICES...DECIDED TO CUT THOSE BY 10 PERCENT INTO THE SLIGHT CHANCE CATEGORY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ KB/CK ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ELKO NV 217 AM PST THU JAN 25 2007 .SYNOPSIS...HIGH PRESSURE WILL SLOWLY SHIFT EAST OVER THE NEXT COUPLE DAYS...ALLOWING WARMER TEMPERATURES TO CREEP NORTHWARD THROUGH THE STATE. BY THE WEEKEND...COLDER AIR WILL SPILL IN FROM THE NORTH PUTTING AN END TO THE SHORT-LIVED WARMING TREND. CONDITIONS WILL REMAIN DRY THROUGH THROUGH EARLY NEXT WEEK. && .SHORT TERM...THURSDAY THROUGH SATURDAY. CLEAR SKIES THIS MORNING WITH IR IMAGERY SHOWING STRONG RIDGING OVER WEST...CENTERED OVER NV. MOST MODELS IN AGREEMENT WITH LOCATION AND INITIAL JOG EAST OF UPPER LOW CIRCULATING OFF CA COAST THIS MORNING. ECMWF AND RUC MODELS SEEM TO NUDGE THE LOW TOO FAR EAST INITIALLY BASED ON CURRENT POSITION. GENERAL PATTERN AGREEMENT BETWEEN NAM/GFS ONLY HOLDS THROUGH FRIDAY. STRONG SOUTHERLY FLOW ALOFT OVER CWA TODAY WILL INDUCE ELEVATED TEMPERATURES OVER HIGHER TERRAIN BUT WITH LITTLE MIXING...SOME OF THE LOWER ELEVATION COLD SPOTS WILL REMAIN NEAR THE FREEZING MARK IN THE AFTERNOON. PORTIONS OF CENTRAL NEVADA WILL APPROACH 60 DEGREES THIS AFTERNOON. SLOWLY DE-AMPLIFYING RIDGE WILL KEEP A SOUTHERLY COMPONENT TO THE FLOW ALOFT OVER CENTRAL NV ON FRIDAY BUT COOLER AIR WILL BEGIN INTRUSION OVER NORTHERN NV. FOR VALLEYS OF NORTHEAST NEVADA WITH STRONG SURFACE INVERSION AND SNOW COVER...DAYTIME TEMPERATURES ARE EXPECTED TO REMAIN IN THE 30S. MODELS HAVE BEEN HAVING DIFFICULT TIME BALANCING ENERGY OF UPPER LOW PRESENTLY OFF WEST COAST. MODEL TO MODEL RUN DIFFERS SIGNIFICANTLY BUT IT IS MOST CERTAIN THAT SATURDAY WILL BE CONTINUED DRY AS TEMPS ALOFT CONTINUE TO COOL AND NORTHWEST FLOW ENSUES. LW .LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY...MODELS ALL MAINTAIN A REX BLOCK PATTERN ALONG THE WEST COAST THROUGH MONDAY BUT DIFFER SOMEWHAT ON THE EVOLUTION OF A HIGH AMPLITUDE RIDGE OR OMEGA BLOCK THAT DEVELOPS AROUND 130W BY THE MIDDLE OF NEXT WEEK. BOTH THE CANADIAN AND ECMWF OPEN UP THE UPPER LOW...CURRENTLY DEVELOPING WEST OF NOCAL...AND TAKE IT INTO THE SOUTHWEST U.S. BY TUESDAY WHILE THE GFS HAS THE LOW RETROGRADING NORTHWESTWARD AND DISSIPATING WEST OF BRITISH COLUMBIA TUESDAY. BOTH SOLUTIONS STILL RESULT IN AN OMEGA BLOCK/HIGH AMPLITUDE RIDGE DEVELOPING ALONG 130W BY THE MIDDLE OF NEXT WEEK WHICH WILL OPEN THE DOOR FOR SHORTWAVE ENERGY...SPILLING SOUTHWARD OUT OF WESTERN CANADA...TO BRING A STRONG NORTHERLY FLOW BACK TO THE CWA. WITH UPPER LOW EXPECTED TO REMAIN IN THE VICINITY OF THE NOCAL COAST THROUGH AT LEAST MONDAY....SHOULD HAVE ENOUGH COOL AIR ALOFT TO HELP MAINTAIN WEAKER VALLEY INVERSIONS ALLOWING FOR MID-30S IN THE SNOW COVERED AREAS WITH MOSTLY 40S ELSEWHERE. MODELS SHOWING GOOD CAA PUSHING INTO NORTHERN AND CENTRAL NV LATE NEXT WEDNESDAY...SO STARTED TRENDING TEMPS DOWN AGAIN. GFS SHOWING SOME LIGHT QPF ENTERING THE CWA AS WELL BUT NOT QUITE READY TO JUMP ON BOARD WITH THAT JUST YET. MCGEE && .AVIATION...TAFS AND TWEBS ADEQUATELY DESCRIBE EXPECTED VFR CONDITIONS. && .LKN WATCHES/WARNINGS/ADVISORIES...NONE. && $$ nv AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 746 PM EST FRI JAN 26 2007 .SHORT TERM /REST OF TONIGHT/... MAY DO ANOTHER UPDATE PRIOR TO SHIFT CHANGE. FOR NOW WE HAVE A BIG UPDATE TO TEMPS FOR EASTERN PORTIONS OF REGION, AS AREA FROM NORTHERN ONEIDA SOUTH TOWARD OTSEGO IS AT OR BELOW ZERO. WE USED RUC TEMPS, MODIFIED BY CURRENT MESO OBS, AS A BEST GUESS AT TREND. ALSO TWEAKED TIMING OF PRECIP WHICH HAS ARRIVED SOONER THAN ANTICIPATED IN THE FINGER LAKES. DJP && .PREV DISCUSSION... /ISSUED 655 PM EST FRI JAN 26 2007/ AVIATION /00Z-24Z/... A BAND OF LIGHT SNOW AHEAD OF A WARM FRONT WILL MOVE THROUGH MOST OF THE TERMINALS WITH A PERIOD OF IFR VSBYS AND MVFR CIGS TONIGHT. SHORT RANGE COMPUTER MODELS APPEAR TO BE SLOW WITH THE ONSET OF PRECIP SO HAVE MADE THE APPROPRIATE ADJUSTMENTS...AND EXPECT IFR CONDITIONS TO REACH ELM-ITH 02Z-04Z. THERE IS SOME DRIER AIR TO THE EAST HALF OF NY...SO THE SPREAD NE THRU BGM-SYR- RME WILL BE A LITTLE SLOWER FROM 05Z-08Z. AVP ON THE FRINGE...BUT SHOULD SEE A FEW HOURS OF MVFR CONDITIONS IN SNOW AFT 06Z. LOOKING AHEAD...LOW PRESSURE MOVES EAST FROM THE UPPER LAKES LATE TONIGHT AND SATURDAY. THIS SHOULD KEEP MVFR CIGS/VSBYS IN THE AREA. MODEL SOLUTIONS HAVE PRECIP CONTINUING WITHIN THE CONVERGENCE AHEAD OF THE LOW...WHICH COULD BE -SN OR -FZDZ. CONFIDENCE RIGHT NOW IS LOW TO INCLUDE EITHER OF THESE IN THIS FCST. FEEL CIGS/VSBYS WILL BE IN MVFR CATEGORY ANYWAY REGARDLESS OF PCPN...SO WILL JUST MONITOR THE POSSIBILITIES AND INCLUDE WITH LATER FCSTS IF NEEDED. WARM FRONT PASSES AREA TOMORROW AFTERNOON...BUT LLVL MOISTURE REMAINS...SO WILL CONTINUE AS MVFR. PREV DISCUSSION... /ISSUED 331 PM EST FRI JAN 26 2007/ SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... VIS IMAGERY SHOWS SHALLOW LAKE EFFECT SNOW SHWRS AND CLDS FROM NW-SE ACRS CWA AS MID-HI CLDS FROM NEXT WAVE OVERSPREAD WRN NY/AND MUCH OF WRN AND SRN PA. THIS NEXT WAVE WAS LEADG TO A WAA SUPPORTED SHIELD OF SNOWS WHICH ARE PROJECTED TO DRY UP SOME AS IT TRACKS E TONIGHT. ACC/S WILL BE LESS THAN ONE INCH AS THE SYSTEM REALLY LACKS MOISTURE. AFTER THE DEEPER WAA PASSES E...THERE IS STILL SHALLOW MOISTURE LEFT OVER AFTER MAIN SNOWS AND WAA PASS E AND DIMINISH LATER TONIGHT. SEE POTENTIAL FOR A LITTLE PATCHY FZDZ FOR A FEW HOURS AFTER MAIN SHIELD OF LIGHT SNOWS DRY UP AS IT WORKS E LATER TONIGHT. FOR SAT...SKIES WILL REMAIN CLDY WITH A LL MOISTURE FEED ACRS MOST OF CWA AND LEAD TO LIGHT SNOWS AND FLURRIES MUCH OF THE DAY. NOT MUCH IN THE WAY OF ACC/S EXPECTED. CLIPPER DROPS THRU FA SAT EVENING WITH FRONT DRAPED ACROSS UPSTATE NY BACK THRU LK MI. FRONT WILL MOVE THROUGH SUN NIGHT/MON MORNING. BOTH GFS AND WRF ADVERTISE WAVE DEVELOPING ALONG THE FRONT SUN NIGHT TO HELP PULL IT THRU. THIS PORTION OF SHORT TERM STILL UP IN THE AIR IN REGARD TO WHEN BEST PCPN CHCS WILL BE. ONCE FNT PASSES...LAKE EFFECT POSSIBLE THRU END OF THE SHORT TERM...ESPECIALLY MONDAY AND MONDAY NIGHT ACROSS FAVORED AREAS AFTER DEEP H5 TROF PASSES EAST. TEMPS WILL CONTINUE TO RUN SLIGHTLY BLO NORMAL AS TROF REMAINS OVER NORTHEAST AND HIGH AMPLITUDE RIDGE BUILDS OVER WEST COAST. LONG TERM /TUESDAY THROUGH FRIDAY/... COLD PATTERN WILL CONTINUE WITH CLOUDS AND SNOW SHOWERS OFF THE LAKES AND AN OCCASIONAL WEAK DISTURBANCE OR REINFORCING COLD WAVE MOVING THROUGH. ON TUESDAY...WEAK LOW PRES AREA WILL MOVE ACROSS THE LAKES AND NEW YORK BRINGING A CHANCE OF SNOW SHOWERS AND FLURRIES. HIGH PRES CENTER WILL PASS ACROSS PA ON WED WITH WLY WINDS OFF THE LAKES. ANOTHER LOW PRES AREA MOVES ACROSS THE LAKES INTO SE CANADA THU BRINGING ANOTHER COLD FRONT THROUGH NY AND PA THU NIGHT WITH SNOW SHOWERS POSSIBLE. AVIATION /18Z-18Z/... SMALL LES BANDS STILL AFFECTG BGM AND ITH. THE ACVTY WAS VERY SHALLOW AND NOT SHOWG UP WELL ON RADARS EXCEPT IN REAL CLOSE. CLDS WERE ALSO THIN AND NOT SHWG UP WELL ON SATL. TEMPS IN THE SFC LYR WERE CLOSE TO -12C SO NOT TAKING MUCH TO PRODUCE IFR/LIFR SHSN. THIS ACVTY WILL WIND DOWN SOON AS INV DROPS FROM SUBSDC AND WINDS BACK MORE W-SW AS NEXT WAVE APPRCHES. NEXT WAVE WAS TRACKING EWRD INTO THE ERN LAKES AND WILL SPREAD MID-HI CLDS OVHD TONIGHT BUT STILL VFR UNTIL LATE...BTWN 6 AND 9Z WHEN SOME LIGHT PRECIP ARRIVES FROM WAA SHIELD. SEE MAINLY MVFR IN LIGHT SNOWS AND CIGS UNTIL THE WAA SHIELD LIFTS TO THE NE BY ARND 15Z. THEN A MOIST SWRLY FLOW ON THE WARM SIDE OF THE WARM FRNT WILL INCREASE LL DWPTS AND WITH REALLY COLD TEMPS HANGING ON NR THE SFC...SEE IFR CONDITIONS DVLPG 15-18Z MOST TAF SITES IN CIGS AND VSBYS. NY/NE PA WILL BASICALLY BE SIMILAR TO WHAT IS HAPPENING IN WI PRESENTLY 24 HOURS FROM NOW. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. && $$ SHORT TERM...DJP ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 915 PM CST FRI JAN 26 2007 .UPDATE...VERY LIGHT BUT MOSTLY MEASURABLE SNOW HAS TARGETED THE NORTHERN RED RIVER VALLEY THIS EVENING AS A LITTLE SHORTWAVE MOVED SOUTHEAST. BUT A BIT OF A BREAK APPEARS TO BE IN ORDER BEFORE THE NEXT SHORTWAVE AND ARCTIC FRONT ENTERS THE U.S...WHICH CURRENTLY IS JUST NORTH OF THE BORDER. MODELS SHOW IMPRESSIVE COLD ADVECTION AT 900 MB NEAR AND JUST BEHIND THIS FRONT AND OBSERVATIONS SHOW TEMPERATURES IN THE SINGLE DIGITS FOLLOWING. ACCEPTED THE RUC DEPICTION OF SURFACE TEMPERATURES TONIGHT WHICH INCREASED THE TEMPERATURE GRADIENT MOVING SOUTH...BUT END RESULT IS NEARLY THE SAME BY MORNING. ANOTHER ROUND OF LIGHT SNOW IS FOLLOWING THE FRONT IN SOUTHERN MANITOBA AND WILL KEEP CHANCE PROBABILITY IN GRIDS SINCE MANY LOCATIONS RECEIVING SNOW WILL NOT MEASURE MORE THAN A TRACE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GV nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE EASTERN ND/GRAND FORKS ND 930 AM CST FRI JAN 26 2007 SURFACE PREFRONTAL TROUGH AND INTITIAL SHOT OF COLD ADVECTION ABOUT THROUGH FORECAST AREA. TEMPERATURES ACROSS REGION AND UPSTREAM REMAIN MILD WITH SECONDARY COLD FRONT STILL ACROSS CENTRAL/NORTHERN CANADIAN PRAIRIE PROVINCES. SO WHILE COLD ADVECTION CONTINUES TODAY STRONGER BAROCLINIC ZONE DOES NOT ARRIVE UNTIL LATE AFTERNOON/EVENING. DEEPER LAYERED RH AND ASSOCIATED LOWER CIGS/-SN TIMED TO ARRIVE AT INTERNATIONAL BORDER AREA AROUND 18Z SPREADING ACROSS NORTHERN FA REMAINDER OF AFTERNOON. OVERALL LACK OF DEEP SNOW PACK AND SOLAR SHOULD PARTIALLY OFFSET COLD ADVECTION ALLOWING SOUTHERN AREAS TO SEE MODEST TEMPERATURE RECOVERY. FARTHER NORTH EXPECT TEMPERATURES TO HOLD FAIRLY STEADY. CURRENT TEMPERATURE SCHEME REFLECTS ABOVE SO ONLY PLANNING MINOR ADJUSTMENTS. WILL ALSO MAKE ADJUSTMENTS TO ANTICIPATED AFTERNOON ARRIVAL OF CIGS AND PCPN POTENTIAL BASED ON CURRENT SATELLITE AND RADAR TRENDS. INCREASING WIND STILL LOOKS ON TRACK HOWEVER STRONGEST PRESSURE RISES TO OUR WEST AND BASED ON RUC MODEL SOUNDINGS NOT CONFIDENT ENOUGH TO HOIST ANY WIND HEADLINES AT THIS TIME. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 748 PM CST FRI JAN 26 2007 .UPDATE... ONLY MADE MINOR ADJUSTMENTS TO THE PACKAGE THIS EVENING TO DELAY ONSET OF PRECIPITATION. CUT DOWN THE COVERAGE OF POPS BEFORE MIDNIGHT AS THE RADAR ECHOES CLOSE TO THE AREA ARE MAINLY VIRGA AND THERE IS A BIT OF LOW LEVEL DRY AIR TO MOISTEN BEFORE PRECIP CHANCES INCREASE TOO MUCH. OTHERWISE FORECAST LOOKS TO BE ON TRACK WITH THE COLD FRONT IN KANSAS AND THE OKLAHOMA PANHANDLE READY TO MOVE INTO THE NORTHWEST CORNER OF THE AREA IN A FEW HOURS. .26. && .PREV DISCUSSION... /ISSUED 1252 PM CST FRI JAN 26 2007/ DISCUSSION... TWO POINTS OF EMPHASIS WITH THIS PARTICULAR FORECAST PACKAGE. THE FIRST POINT IS WITH THE SMALL BUT VIGOROUS UPPER LOW NEAR EL PASO. RUC/GFS MODEL INITIALIZATIONS ARE BEST WITH THE NAM TOO FAR SOUTHWEST. THIS APPROACH HAS THE LOW REACHING THE CENTRAL TEXAS PANHANDLE BY 06 SAT...HOBART BY 12Z...THEN MCALESTER BY 18Z. THE LOW IS EXPECTED TO SLOWLY WEAKEN AS IT MOVES ACROSS THE REGION...BUT STILL EXPECT RATHER STRONG DYNAMICS NEAR AND JUST AHEAD OF ITS PATH. MOISTURE IS RATHER BLEAK AT THE MOMENT BUT VISIBILE SATELLITE IMAGERY ALREADY SHOWS LOW/MID LEVEL MOISTURE INCREASING OVER SOUTH TEXAS WHICH THE MODELS PICK UP ON AND BRING TO NEAR THE RED RIVER OVERNIGHT. HAVE RAISED POPS ACROSS THE SOUTHEASTERN HALF OF THE AREA LATE TONIGHT/EARLY SATURDAY AND INTRODUCED ISOLATED THUNDER DUE TO STEEPENING 700-500 MB LAPSE RATES. SNOW CHANCES SEEM LOW AT BEST AS HIGHS IN THE 50S AND 60S THIS AFTERNOON WILL BE REPLACED WITH NEAR FREEZING TEMPERATURES JUST AS THE LOW EXITS THE REGION. CAN NOT COMPLETELY RULE OUT SNOW...BUT HAVE LIMITED ITS EXTENT TO NORTHEN AND WESTERN PERIPHERIES OF THE LOW`S INFLUENCE. AFTER THE LOW LEAVES THE REGION MIDDAY SATURDAY...A COLD FRONT ASSOCIATED WITH A NORTHERN LATITUDES SHORTWAVE TROUGH PASSES WITH THE FIRST OF MANY SURGES OF COLDER AIR THAT ARE FORECAST THROUGH NEXT WEEK. OTHER THAN ADJUSTING TEMPERATURES DOWN A FEW DEGREES SOME DAYS NEXT WEEK...CONSISTENT WITH DEPARTURES FROM NORMAL AVERAGING ABOUT 10 DEGREES...IT IS DIFFICULT TO ARGUE FOR MAJOR CHANGES. MODEL CONSENSUS CONTINUES TO SUPPORT PERIODIC INTRUSIONS OF CANADIAN AIRMASSES WITH THE POTENTIAL FOR SOUTHERN STREAM DISTURBANCES TO UNDERCUT A WEST COAST RIDGE AND AFFECT THE AREA. THE MAIN CONCERN HOWEVER IS THAT THE DEEPEST MOISTURE WILL LIKELY BE INCORPORATED INTO NORTHERN GULF OF MEXICO AND EAST COAST STORMS WITH OUR AIRMASS LIKELY REMAINING QUITE DRY. BELIEVE THE GFS IS HAS OVERDONE QPF/SNOW AMOUNTS FOR OUR AREA NEXT WEEK...BUT CAN NOT RULE OUT LIGHTER AMOUNTS WITH ONE OR MORE OF THESE DISTURBANCES. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 34 40 23 39 / 40 30 10 10 HOBART OK 32 40 22 41 / 30 20 10 10 WICHITA FALLS TX 39 43 26 41 / 40 30 10 10 GAGE OK 28 37 19 38 / 20 10 10 10 PONCA CITY OK 30 38 18 36 / 30 20 10 0 DURANT OK 44 48 27 40 / 50 50 10 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1252 PM CST FRI JAN 26 2007 .DISCUSSION... TWO POINTS OF EMPHASIS WITH THIS PARTICULAR FORECAST PACKAGE. THE FIRST POINT IS WITH THE SMALL BUT VIGOROUS UPPER LOW NEAR EL PASO. RUC/GFS MODEL INITIALIZATIONS ARE BEST WITH THE NAM TOO FAR SOUTHWEST. THIS APPROACH HAS THE LOW REACHING THE CENTRAL TEXAS PANHANDLE BY 06 SAT...HOBART BY 12Z...THEN MCALESTER BY 18Z. THE LOW IS EXPECTED TO SLOWLY WEAKEN AS IT MOVES ACROSS THE REGION...BUT STILL EXPECT RATHER STRONG DYNAMICS NEAR AND JUST AHEAD OF ITS PATH. MOISTURE IS RATHER BLEAK AT THE MOMENT BUT VISIBILE SATELLITE IMAGERY ALREADY SHOWS LOW/MID LEVEL MOISTURE INCREASING OVER SOUTH TEXAS WHICH THE MODELS PICK UP ON AND BRING TO NEAR THE RED RIVER OVERNIGHT. HAVE RAISED POPS ACROSS THE SOUTHEASTERN HALF OF THE AREA LATE TONIGHT/EARLY SATURDAY AND INTRODUCED ISOLATED THUNDER DUE TO STEEPENING 700-500 MB LAPSE RATES. SNOW CHANCES SEEM LOW AT BEST AS HIGHS IN THE 50S AND 60S THIS AFTERNOON WILL BE REPLACED WITH NEAR FREEZING TEMPERATURES JUST AS THE LOW EXITS THE REGION. CAN NOT COMPLETELY RULE OUT SNOW...BUT HAVE LIMITED ITS EXTENT TO NORTHEN AND WESTERN PERIPHERIES OF THE LOW`S INFLUENCE. AFTER THE LOW LEAVES THE REGION MIDDAY SATURDAY...A COLD FRONT ASSOCIATED WITH A NORTHERN LATITUDES SHORTWAVE TROUGH PASSES WITH THE FIRST OF MANY SURGES OF COLDER AIR THAT ARE FORECAST THROUGH NEXT WEEK. OTHER THAN ADJUSTING TEMPERATURES DOWN A FEW DEGREES SOME DAYS NEXT WEEK...CONSISTENT WITH DEPARTURES FROM NORMAL AVERAGING ABOUT 10 DEGREES...IT IS DIFFICULT TO ARGUE FOR MAJOR CHANGES. MODEL CONSENSUS CONTINUES TO SUPPORT PERIODIC INTRUSIONS OF CANADIAN AIRMASSES WITH THE POTENTIAL FOR SOUTHERN STREAM DISTURBANCES TO UNDERCUT A WEST COAST RIDGE AND AFFECT THE AREA. THE MAIN CONCERN HOWEVER IS THAT THE DEEPEST MOISTURE WILL LIKELY BE INCORPORATED INTO NORTHERN GULF OF MEXICO AND EAST COAST STORMS WITH OUR AIRMASS LIKELY REMAINING QUITE DRY. BELIEVE THE GFS IS HAS OVERDONE QPF/SNOW AMOUNTS FOR OUR AREA NEXT WEEK...BUT CAN NOT RULE OUT LIGHTER AMOUNTS WITH ONE OR MORE OF THESE DISTURBANCES. .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 34 40 23 39 / 40 30 10 10 HOBART OK 32 40 22 41 / 30 20 10 10 WICHITA FALLS TX 39 43 26 41 / 40 30 10 10 GAGE OK 28 37 19 38 / 20 10 10 10 PONCA CITY OK 30 38 18 36 / 30 20 10 0 DURANT OK 44 48 27 40 / 50 50 10 0 .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. $$ JAMES ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1035 AM EST THU JAN 25 2007 .SHORT TERM /REST OF TODAY/... AS UPPER SHORTWAVE MOVES INTO MTNS SNOW IS INCREASING OVER THE TN BORDER COUNTIES...MAINLY IN THE WARNED AREA...FROM MADISON UP TO AVERY COUNTY...WHERE THE BEST MOISTURE IS EXPECTED. WINDS ARE ALSO INCREASING FROM THE NW AND BECOMING GUSTY ACROSS THE MTNS. HAVE TWEAKED THE HOURLY TEMPS/DEW POINTS/RH AND WINDS WITH LATEST GUIDANCE. NO CHANGE TO WARNING/ADVISORY AREAS FOR THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 448 AM EST THU JAN 25 2007/ ..CORRECTED TO ADD LAKE WIND ADVISORY... SHORT TERM /TODAY THROUGH TONIGHT/... LATEST IR SATELLITE IMAGES SHOW UPSLOPE CLOUDS INCREASING ACROSS THE NC MOUNTAINS THIS MORNING. INCREASING NW FLOW...PASSING VORT MAX...AND IDEAL CRYSTAL GROWTH TEMPERATURES SHOULD SUPPORT ISO TO SCT SHSN THIS MORNING ACROSS THE TN BORDER AREAS. A WEB CAM NEAR BANNER ELK SHOWS A FEW FLURRIES CURRENTLY FALLING. SNOW FALL RATES SHOULD GRADUALLY INCREASE THIS MORNING AS CAA CONTINUES AND WIND SPEEDS INCREASE. RUC40 AND W/V IMAGES INDICATES A W/V NEAR LAKE MICHIGAN AT THIS TIME...WHICH IS A LITTLE WEST OF THE 0Z GFS. THE VORT SHOULD PASS JUST NORTH OF THE NORTHERN MOUNTAINS THIS AFTERNOON. AS THE VORT PASSES...CAA WILL MAKE THE GREATEST SURGE AND LLVL EPV BECOMES MORE DEFINED. THIS SHOULD RESULT IN SEVERAL BANDS OF SHSN TO PASS ACROSS WESTERN NORTH CAROLINA BETWEEN 18-0Z. AREA FORECAST SOUNDINGS INDICATE THAT A 3-6 HR WINDOW DEVELOPS THIS AFTERNOON WHERE MOISTURE PROFILES AND DENDRITIC GROWTH ZONES LOOK FAVORABLE FOR ACCUMULATING SNOWFALL. AFTER 0Z...NW FLOW WILL GRADUALLY STRENGTHEN...APPROACHING 50 KTS AT H85 AFTER 3Z. THESE WINDS SHOULD COMBINE WITH THE REMAINING SHALLOW MOISTURE TO PROVIDE ADDITIONAL LIGHT ACCUMULATIONS FOR THE REST OF THE NIGHT. BY FRIDAY MORNING...THE AREA FROM AVERY TO MADISON COUNTIES SHOULD SEE SEVERAL INCHES OF SNOWFALL...AVERAGING 3 INCHES AND UP TO 5 INCHES POSSIBLE IN SPOTS. BLOWING SNOW AND WIND CHILLS AT OR BELOW ZERO SHOULD ALSO DEVELOP ACROSS THE MOUNTAINS AFTER 6Z FRI. THE LATEST FORECAST AGREES WELL WITH THE CURRENT WINTER STORM WARNING AND ADVISORIES. IN ADDITION...AREAS ADJACENT TO THE CURRENT HIGHLIGHTED AREA MAY SEE WIND ADVISORY LEVEL WINDS THIS AFTERNOON AND TONIGHT. EAST OF THE MTNS...TODAY AND TONIGHT WILL REMAIN DRY AND GUSTY. CIRRUS SHOULD PUSH EAST OF THE FORECAST AREA THIS AFTERNOON...RESULTING IN A PARTLY SUNNY SKY. TEMPERATURES WILL REMAIN BELOW NORMAL AS STRONG CAA ARRIVES THIS AFTERNOON AND SLIDES OVER THE ENTIRE CWA TONIGHT. LOWS TONIGHT WILL BE COLD...WITH TEENS NORTH AND L20S SOUTH. LONG TERM /FRIDAY THROUGH WEDNESDAY/... COULD BE SOME BLOWING SNOW REMAINING FRIDAY MORNING WITH BREEZY CONDITIONS ACROSS THE MOUNTAINS...BUT SNOW SHOWERS END AS LOW LEVEL MOISTURE DRIES UP. WINDS DIMINISH THROUGH THE DAY AS PRESSURE GRADIENT RELAXES AS HIGH PRESSURE BUILDS INTO THE AREA. DRY WEATHER WITH BELOW NORMAL TEMPS FRIDAY AND FRIDAY NIGHT. HEIGHTS AND THICKNESSES RISE DRAMATICALLY SATURDAY AS POLAR VORTEX PULLS EAST AND FLAT RIDGING DEVELOPS AHEAD OF APPROACHING UPPER LOW EJECTING EASTWARD FROM THE SOUTHWEST. THIS SHOULD PRODUCE ABOVE NORMAL HIGHS...BUT DID TREND TOWARD THE COOLER GUIDANCE. MODELS COMING INTO BETTER AGREEMENT WITH TRACK OF THE EJECTING SW LOW... BUT NAM SIGNIFICANTLY SLOWER THAN OTHERS. THAT SAID...21Z SREF IS LENDING SOME CREDENCE TO THE SLOWER SOLUTION. THE SREF ALSO INDICATES LIGHT PRECIP LIKELY FOR THE CWFA SATURDAY NIGHT. FOR NOW BROUGHT SOME CHC POP INTO THE NC MOUNTAINS AND NE GA...AND SLIGHT CHC EAST OF THERE. GFS IS COLDER THAN THE NAM INDICATING P-TYPE WOULD BE ALL SNOW FOR THE NC MTNS. USING A MODEL BLEND...PRODUCES A RAIN CHANGING TO SNOW P-TYPE. THEREFORE HAVE RAIN OR SNOW MENTIONED THERE WITH RAIN TO THE SOUTH. ANY PRECIP PRODUCED BY THE GULF LOW ENDS SUNDAY MORNING WITH A SIMILAR P-TYPE BREAK UP. NW FLOW SNOW SHOWERS POSSIBLE SUNDAY AND SUNDAY NIGHT. A BREAK IN THE PRECIP MONDAY...THEN A CLIPPER SYSTEM AND NORTHWEST FLOW BRING THE POSSIBILITY OF SNOW SHOWERS TO THE MOUNTAINS AGAIN MONDAY NIGHT THROUGH TUESDAY NIGHT. FOR NOW ONLY HAVE SLIGHT CHC POP. DRY FORECAST AS HIGH PRESSURE RETURNS WEDNESDAY. TEMPERATURES A LITTLE BELOW NORMAL SUNDAY RETURNING TO BELOW NORMAL MONDAY THROUGH WEDNESDAY. AVIATION /10Z-06Z/... THE PERSISTENT BKN TO OVC CIRRUS THAT AS REMAINED OVER THE WESTERN CAROLINAS OVER THE PAST SEVERAL DAYS WILL COME TO AN END THIS AFTERNOON. THE THINNING CIRRUS WILL RESULT IN FEW TO SCT SKY COVER EAST OF THE MTNS THIS AFTERNOON AND EVENING. HOWEVER...THE MTNS WILL SEE WIDESPREAD CAA AND NW FLOW CLOUDS DEVELOPING THIS MORNING...AND PEAKING THIS AFTERNOON AND EVENING. THE ARRIVAL OF THE CAA WILL RESULT A 5 TO 6 KFT THICK MIXING LAYER AFTER NOON. MOMENTUM TRANSFER WITHIN THE MIXING LAYER WILL LIKELY RESULT IN GUSTY CONDITIONS AFTER 15-18Z. THE WIND GUSTS WILL BE THE GREATEST AT KAVL...WITH FREQUENT GUSTS TO 25-30 KTS EXPECTED DURING THE AFTERNOON AND OVERNIGHT. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...LAKE WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR GAZ010-017. NC...WINTER STORM WARNING UNTIL 6 AM EST FRIDAY FOR NCZ033-048>050. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ051>053- 058-059-062. WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ063>065-501-503-505- 507-509. SC...LAKE WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR SCZ001>003. && $$ SHORT TERM...RB sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 448 AM EST THU JAN 25 2007 ...CORRECTED TO ADD LAKE WIND ADVISORY... .SHORT TERM /TODAY THROUGH TONIGHT/... LATEST IR SATELLITE IMAGES SHOW UPSLOPE CLOUDS INCREASING ACROSS THE NC MOUNTAINS THIS MORNING. INCREASING NW FLOW...PASSING VORT MAX...AND IDEAL CRYSTAL GROWTH TEMPERATURES SHOULD SUPPORT ISO TO SCT SHSN THIS MORNING ACROSS THE TN BORDER AREAS. A WEB CAM NEAR BANNER ELK SHOWS A FEW FLURRIES CURRENTLY FALLING. SNOW FALL RATES SHOULD GRADUALLY INCREASE THIS MORNING AS CAA CONTINUES AND WIND SPEEDS INCREASE. RUC40 AND W/V IMAGES INDICATES A W/V NEAR LAKE MICHIGAN AT THIS TIME...WHICH IS A LITTLE WEST OF THE 0Z GFS. THE VORT SHOULD PASS JUST NORTH OF THE NORTHERN MOUNTAINS THIS AFTERNOON. AS THE VORT PASSES...CAA WILL MAKE THE GREATEST SURGE AND LLVL EPV BECOMES MORE DEFINED. THIS SHOULD RESULT IN SEVERAL BANDS OF SHSN TO PASS ACROSS WESTERN NORTH CAROLINA BETWEEN 18-0Z. AREA FORECAST SOUNDINGS INDICATE THAT A 3-6 HR WINDOW DEVELOPS THIS AFTERNOON WHERE MOISTURE PROFILES AND DENDRITIC GROWTH ZONES LOOK FAVORABLE FOR ACCUMULATING SNOWFALL. AFTER 0Z...NW FLOW WILL GRADUALLY STRENGTHEN...APPROACHING 50 KTS AT H85 AFTER 3Z. THESE WINDS SHOULD COMBINE WITH THE REMAINING SHALLOW MOISTURE TO PROVIDE ADDITIONAL LIGHT ACCUMULATIONS FOR THE REST OF THE NIGHT. BY FRIDAY MORNING...THE AREA FROM AVERY TO MADISON COUNTIES SHOULD SEE SEVERAL INCHES OF SNOWFALL...AVERAGING 3 INCHES AND UP TO 5 INCHES POSSIBLE IN SPOTS. BLOWING SNOW AND WIND CHILLS AT OR BELOW ZERO SHOULD ALSO DEVELOP ACROSS THE MOUNTAINS AFTER 6Z FRI. THE LATEST FORECAST AGREES WELL WITH THE CURRENT WINTER STORM WARNING AND ADVISORIES. IN ADDITION...AREAS ADJACENT TO THE CURRENT HIGHLIGHTED AREA MAY SEE WIND ADVISORY LEVEL WINDS THIS AFTERNOON AND TONIGHT. EAST OF THE MTNS...TODAY AND TONIGHT WILL REMAIN DRY AND GUSTY. CIRRUS SHOULD PUSH EAST OF THE FORECAST AREA THIS AFTERNOON...RESULTING IN A PARTLY SUNNY SKY. TEMPERATURES WILL REMAIN BELOW NORMAL AS STRONG CAA ARRIVES THIS AFTERNOON AND SLIDES OVER THE ENTIRE CWA TONIGHT. LOWS TONIGHT WILL BE COLD...WITH TEENS NORTH AND L20S SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... COULD BE SOME BLOWING SNOW REMAINING FRIDAY MORNING WITH BREEZY CONDITIONS ACROSS THE MOUNTAINS...BUT SNOW SHOWERS END AS LOW LEVEL MOISTURE DRIES UP. WINDS DIMINISH THROUGH THE DAY AS PRESSURE GRADIENT RELAXES AS HIGH PRESSURE BUILDS INTO THE AREA. DRY WEATHER WITH BELOW NORMAL TEMPS FRIDAY AND FRIDAY NIGHT. HEIGHTS AND THICKNESSES RISE DRAMATICALLY SATURDAY AS POLAR VORTEX PULLS EAST AND FLAT RIDGING DEVELOPS AHEAD OF APPROACHING UPPER LOW EJECTING EASTWARD FROM THE SOUTHWEST. THIS SHOULD PRODUCE ABOVE NORMAL HIGHS...BUT DID TREND TOWARD THE COOLER GUIDANCE. MODELS COMING INTO BETTER AGREEMENT WITH TRACK OF THE EJECTING SW LOW... BUT NAM SIGNIFICANTLY SLOWER THAN OTHERS. THAT SAID...21Z SREF IS LENDING SOME CREDENCE TO THE SLOWER SOLUTION. THE SREF ALSO INDICATES LIGHT PRECIP LIKELY FOR THE CWFA SATURDAY NIGHT. FOR NOW BROUGHT SOME CHC POP INTO THE NC MOUNTAINS AND NE GA...AND SLIGHT CHC EAST OF THERE. GFS IS COLDER THAN THE NAM INDICATING P-TYPE WOULD BE ALL SNOW FOR THE NC MTNS. USING A MODEL BLEND...PRODUCES A RAIN CHANGING TO SNOW P-TYPE. THEREFORE HAVE RAIN OR SNOW MENTIONED THERE WITH RAIN TO THE SOUTH. ANY PRECIP PRODUCED BY THE GULF LOW ENDS SUNDAY MORNING WITH A SIMILAR P-TYPE BREAK UP. NW FLOW SNOW SHOWERS POSSIBLE SUNDAY AND SUNDAY NIGHT. A BREAK IN THE PRECIP MONDAY...THEN A CLIPPER SYSTEM AND NORTHWEST FLOW BRING THE POSSIBILITY OF SNOW SHOWERS TO THE MOUNTAINS AGAIN MONDAY NIGHT THROUGH TUESDAY NIGHT. FOR NOW ONLY HAVE SLIGHT CHC POP. DRY FORECAST AS HIGH PRESSURE RETURNS WEDNESDAY. TEMPERATURES A LITTLE BELOW NORMAL SUNDAY RETURNING TO BELOW NORMAL MONDAY THROUGH WEDNESDAY. && .AVIATION /10Z-06Z/... THE PERSISTENT BKN TO OVC CIRRUS THAT AS REMAINED OVER THE WESTERN CAROLINAS OVER THE PAST SEVERAL DAYS WILL COME TO AN END THIS AFTERNOON. THE THINNING CIRRUS WILL RESULT IN FEW TO SCT SKY COVER EAST OF THE MTNS THIS AFTERNOON AND EVENING. HOWEVER...THE MTNS WILL SEE WIDESPREAD CAA AND NW FLOW CLOUDS DEVELOPING THIS MORNING...AND PEAKING THIS AFTERNOON AND EVENING. THE ARRIVAL OF THE CAA WILL RESULT A 5 TO 6 KFT THICK MIXING LAYER AFTER NOON. MOMENTUM TRANSFER WITHIN THE MIXING LAYER WILL LIKELY RESULT IN GUSTY CONDITIONS AFTER 15-18Z. THE WIND GUSTS WILL BE THE GREATEST AT KAVL...WITH FREQUENT GUSTS TO 25-30 KTS EXPECTED DURING THE AFTERNOON AND OVERNIGHT. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM EST FRIDAY FOR GAZ010-017. NC...WINTER STORM WARNING UNTIL 6 AM EST FRIDAY FOR NCZ033-048>050. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ051>053- 058-059-062. WIND ADVISORY FROM NOON TODAY TO 6 AM EST FRIDAY FOR NCZ063>065-501-503-505-507-509. SC...LAKE WIND ADVISORY FROM NOON TODAY TO 6 AM EST FRIDAY FOR SCZ001>003. && $$ SHORT TERM...NED LONG TERM...RWH AVIATION...NED sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 410 AM EST THU JAN 25 2007 .SHORT TERM /TODAY THROUGH TONIGHT/... LATEST IR SATELLITE IMAGES SHOW UPSLOPE CLOUDS INCREASING ACROSS THE NC MOUNTAINS THIS MORNING. INCREASING NW FLOW...PASSING VORT MAX...AND IDEAL CRYSTAL GROWTH TEMPERATURES SHOULD SUPPORT ISO TO SCT SHSN THIS MORNING ACROSS THE TN BORDER AREAS. A WEB CAM NEAR BANNER ELK SHOWS A FEW FLURRIES CURRENTLY FALLING. SNOW FALL RATES SHOULD GRADUALLY INCREASE THIS MORNING AS CAA CONTINUES AND WIND SPEEDS INCREASE. RUC40 AND W/V IMAGES INDICATES A W/V NEAR LAKE MICHIGAN AT THIS TIME...WHICH IS A LITTLE WEST OF THE 0Z GFS. THE VORT SHOULD PASS JUST NORTH OF THE NORTHERN MOUNTAINS THIS AFTERNOON. AS THE VORT PASSES...CAA WILL MAKE THE GREATEST SURGE AND LLVL EPV BECOMES MORE DEFINED. THIS SHOULD RESULT IN SEVERAL BANDS OF SHSN TO PASS ACROSS WESTERN NORTH CAROLINA BETWEEN 18-0Z. AREA FORECAST SOUNDINGS INDICATE THAT A 3-6 HR WINDOW DEVELOPS THIS AFTERNOON WHERE MOISTURE PROFILES AND DENDRITIC GROWTH ZONES LOOK FAVORABLE FOR ACCUMULATING SNOWFALL. AFTER 0Z...NW FLOW WILL GRADUALLY STRENGTHEN...APPROACHING 50 KTS AT H85 AFTER 3Z. THESE WINDS SHOULD COMBINE WITH THE REMAINING SHALLOW MOISTURE TO PROVIDE ADDITIONAL LIGHT ACCUMULATIONS FOR THE REST OF THE NIGHT. BY FRIDAY MORNING...THE AREA FROM AVERY TO MADISON COUNTIES SHOULD SEE SEVERAL INCHES OF SNOWFALL...AVERAGING 3 INCHES AND UP TO 5 INCHES POSSIBLE IN SPOTS. BLOWING SNOW AND WIND CHILLS AT OR BELOW ZERO SHOULD ALSO DEVELOP ACROSS THE MOUNTAINS AFTER 6Z FRI. THE LATEST FORECAST AGREES WELL WITH THE CURRENT WINTER STORM WARNING AND ADVISORIES. IN ADDITION...AREAS ADJACENT TO THE CURRENT HIGHLIGHTED AREA MAY SEE WIND ADVISORY LEVEL WINDS THIS AFTERNOON AND TONIGHT. EAST OF THE MTNS...TODAY AND TONIGHT WILL REMAIN DRY AND GUSTY. CIRRUS SHOULD PUSH EAST OF THE FORECAST AREA THIS AFTERNOON...RESULTING IN A PARTLY SUNNY SKY. TEMPERATURES WILL REMAIN BELOW NORMAL AS STRONG CAA ARRIVES THIS AFTERNOON AND SLIDES OVER THE ENTIRE CWA TONIGHT. LOWS TONIGHT WILL BE COLD...WITH TEENS NORTH AND L20S SOUTH. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... COULD BE SOME BLOWING SNOW REMAINING FRIDAY MORNING WITH BREEZY CONDITIONS ACROSS THE MOUNTAINS...BUT SNOW SHOWERS END AS LOW LEVEL MOISTURE DRIES UP. WINDS DIMINISH THROUGH THE DAY AS PRESSURE GRADIENT RELAXES AS HIGH PRESSURE BUILDS INTO THE AREA. DRY WEATHER WITH BELOW NORMAL TEMPS FRIDAY AND FRIDAY NIGHT. HEIGHTS AND THICKNESSES RISE DRAMATICALLY SATURDAY AS POLAR VORTEX PULLS EAST AND FLAT RIDGING DEVELOPS AHEAD OF APPROACHING UPPER LOW EJECTING EASTWARD FROM THE SOUTHWEST. THIS SHOULD PRODUCE ABOVE NORMAL HIGHS...BUT DID TREND TOWARD THE COOLER GUIDANCE. MODELS COMING INTO BETTER AGREEMENT WITH TRACK OF THE EJECTING SW LOW... BUT NAM SIGNIFICANTLY SLOWER THAN OTHERS. THAT SAID...21Z SREF IS LENDING SOME CREDENCE TO THE SLOWER SOLUTION. THE SREF ALSO INDICATES LIGHT PRECIP LIKELY FOR THE CWFA SATURDAY NIGHT. FOR NOW BROUGHT SOME CHC POP INTO THE NC MOUNTAINS AND NE GA...AND SLIGHT CHC EAST OF THERE. GFS IS COLDER THAN THE NAM INDICATING P-TYPE WOULD BE ALL SNOW FOR THE NC MTNS. USING A MODEL BLEND...PRODUCES A RAIN CHANGING TO SNOW P-TYPE. THEREFORE HAVE RAIN OR SNOW MENTIONED THERE WITH RAIN TO THE SOUTH. ANY PRECIP PRODUCED BY THE GULF LOW ENDS SUNDAY MORNING WITH A SIMILAR P-TYPE BREAK UP. NW FLOW SNOW SHOWERS POSSIBLE SUNDAY AND SUNDAY NIGHT. A BREAK IN THE PRECIP MONDAY...THEN A CLIPPER SYSTEM AND NORTHWEST FLOW BRING THE POSSIBILITY OF SNOW SHOWERS TO THE MOUNTAINS AGAIN MONDAY NIGHT THROUGH TUESDAY NIGHT. FOR NOW ONLY HAVE SLIGHT CHC POP. DRY FORECAST AS HIGH PRESSURE RETURNS WEDNESDAY. TEMPERATURES A LITTLE BELOW NORMAL SUNDAY RETURNING TO BELOW NORMAL MONDAY THROUGH WEDNESDAY. && .AVIATION /09Z-06Z/... THE PERSISTENT BKN TO OVC CIRRUS THAT AS REMAINED OVER THE WESTERN CAROLINAS OVER THE PAST SEVERAL DAYS WILL COME TO AN END THIS AFTERNOON. THE THINNING CIRRUS WILL RESULT IN FEW TO SCT SKY COVER EAST OF THE MTNS THIS AFTERNOON AND EVENING. HOWEVER...THE MTNS WILL SEE WIDESPREAD CAA AND NW FLOW CLOUDS DEVELOPING THIS MORNING...AND PEAKING THIS AFTERNOON AND EVENING. THE ARRIVAL OF THE CAA WILL RESULT A 5 TO 6 KFT THICK MIXING LAYER AFTER NOON. MOMENTUM TRANSFER WITHIN THE MIXING LAYER WILL LIKELY RESULT IN GUSTY CONDITIONS AFTER 15-18Z. THE WIND GUSTS WILL BE THE GREATEST AT KAVL...WITH FREQUENT GUSTS TO 25-30 KTS EXPECTED DURING THE AFTERNOON AND OVERNIGHT. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...WINTER STORM WARNING UNTIL 6 AM EST FRIDAY FOR NCZ033-048>050. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ051>053- 058-059-062. WIND ADVISORY FROM NOON TODAY TO 6 AM EST FRIDAY FOR NCZ063>065-501-503-505-507-509. SC...NONE. && $$ SHORT TERM...NED LONG TERM...RWH AVIATION...NED sc AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 855 PM CST THU JAN 25 2007 .DISCUSSION... WIDESPREAD DENSE/FREEZING FOG PERSISTING FROM THE JAMES VALLEY EAST INTO NORTHWEST IOWA AND SOUTHWEST MINNESOTA...THOUGH FOG HAVING A HARD TIME PUSHING EAST OF THE BUFFALO RIDGE WITH GREATER MIXING AND SLIGHT DOWNSLOPE DRYING OUT BOUNDARY LAYER EAST OF THE RIDGE AXIS. SCATTERED SFC OBSERVATIONS STILL REPORTING SOME -SN AND HAVE BEEN SEEING A LIGHT RIME ACCRETION ON UNTREATED SURFACES WITH THE LOWEST VISIBILITIES AS WELL. 00Z RUNS OF BOTH NAM AND RUC ATTEMPTING TO SCOUR OUT THE HIGHEST BOUNDARY LAYER MOISTURE FROM THE WEST AFTER 06Z. AFTER A COUPLE OF NIGHTS OF WISHFUL THINKING REGARDING CLEARING OF THE LOW CLOUDS...WILL REMAIN ON THE PESSIMISTIC SIDE FOR NOW AND KEEP OUR FREEZING FOG ADVISORY AS IS UNTIL 10Z FOR NOW. REMAINDER OF THE FORECAST IN DECENT SHAPE. AS EARLIER SHIFT ANTICIPATED...STARTING TO SEE TEMPS EDGE UPWARD A BIT WITH INFLUX OF MOISTURE FROM THE SOUTH. HAVE LIKELY SEEN OUR LOWS IN MANY PLACES ALREADY...AND MADE ADJUSTMENT TO THE GRIDS ACCORDINGLY. ADDITIONAL UPDATES TO THE ZFP NOT PLANNED AT THIS TIME. && .AVIATION... LIFR CIGS AND VSBYS IN FZFG COVERING MUCH OF THE FORECAST AREA FROM THE JAMES RIVER TO THE BUFFALO RIDGE...AS WELL AS INTO NORTHWEST IOWA. CLEARING LINE AS OF 03Z RUNNING FROM WESTERN EDGE OF BEADLE COUNTY...TO JUST WEST OF KMHE AND KYKN. DOES NOT APPEAR TO BE MAKING MUCH EASTWARD PROGRESS...HOWEVER LATEST MODELS SHOW RAPID DECREASE IN BOUNDARY LAYER MOISTURE FROM WEST TO EAST ACROSS THE FORECAST AREA IN 06Z-09Z TIME FRAME. COULD SEE QUICK IMPROVEMENT IN VSBYS/CIGS...ESPECIALLY AT KHON AROUND 06Z. && .PREV DISCUSSION... ON FRI...SFC FNT WL DROP THRU CWA IN THE MORN...WITH CAA AT H85. THIS SHUD CREATE CONDITIONS FOR GOOD MIXING AND THIS WARMER TEMPS...MAIN ALONG AND E OF JAMES RVR. ALSO BUMPED UP WNDS AS CUD SEE GUSTS TO 35 MPH. MAY NEED TO WATCH FOR POT WND ADVY. ARCTIC AIR WL MOVE INTO CWA LATE FRI NIGHT INTO SAT MORN BEHIND S/W. HIGH TEMPS WL LIKELY OCCUR IN MORN...FOLLOWED BY FALLING TEMPS. STRATUS ALSO EXPECTED TO SPREAD S ACRS CWA ON SAT AND THERE CUD BE SOME LIGHT SNOW OR FLURRIES. COLD DAY ON TAP FOR SUN...BUT SHUD SEE A LTL MORE SUN THAN ON SAT. LOW TEMPS SUN NITE WL PBLY OCCUR IN EVE...WITH SLOWLY RISING TEMPS AS LOW LEVEL FLOW BECOMES SLY AHEAD OF NEXT FNT. IN THE EXTENDED MON THRU THU...THE MAIN STORY WL BE COLD WX CONTINUING WITH REALLY NO BREAKS. THE MEDR MODELS CONT TO BE IN PRETTY GOOD AGREEMENT ON SHOWING FROPA WITH MODIFIED ARCTIC AIR IN THIS AREA EARLY MONDAY...AND AGAIN LATE TUE NIGHT AND EARLY WED. THEREFORE KEPT SMALL POPS GOING FOR THE DAY PD ON MON...AND INTRODUCED SMALL POPS ON WED. BOTH DAYS ARE POST FRONTAL AND SHOW SOME CLOUD COVER...WITH SUPPORT ON BOTH THE GFS AND ECMWF ON THIS. I MAY BE TOO LOW WITH THE CLOUD COVER ON WED. WOULD NOT BE SURPRISED WHEN THE TIME COMES TO SEE SOME NON DIURNAL READINGS ON MON AND WED...POSSIBLY WITH MORNING HIGHS THEN FALLING TEMPS. TUE STILL SHOWS AS THE DAY WITH THE OVERALL WARMEST AIRMASS. BUT OF COURSE WARMING WL BE TEMPERED WITH SNOW COVER OVR MUCH OF THE FA. AND IF AND WHEN THE WINDS SHIFT AROUND TO THE SOUTH...THE INVERSION MAY FORCE THE WINDS TO A SELY DIRECTION WHICH IS NEVER GOOD FOR WARMING. LIKE TODAY...ONCE THE WINDS GO AROUND TO A S OR SE DIRECTION AHEAD OF WEDNESDAYS FRONT...WE COULD EVEN GET STRATUS. CANNOT RULE THAT OUT. ON THU..LOOKS COLD BEHIND WEDNESDAYS FRONT. BUT THE MOST BRUTAL AIR CONTS TO BE SHOWN BY BOTH THE ECMWF AND GFS ADVECTING INTO OUR FA BY NEXT FRI AND THRU THE WEEKEND. COLDER THAN -30C AT H85 ON THE LATEST GFS IN OUR FA BY 12Z SAT. CLOUDS OR NOT...THAT WOULD BE COLD. FOR LOW TEMPS...THEY COULD BE TEMPERED BY SOME CLOUD COVER IN THE MORNINGS AND ALSO WITH SOME CONTINUOUS CAA MIXING WIND THAT WL LIKELY OCCUR AFTER THE FROPAS. SO EVEN THOUGH THE DAYTIME MAY BE SEASONABLY CHILLY...THE NIGHTS TEMP WISE MAY NOT BE FRIGID. ANY CLEARING EARLY IN THE MORNING WITH ANY DROP OFF OF WIND THOUGH...AND TEMPS WL PLUMMET. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...FREEZING FOG ADVISORY UNTIL 4 AM FOR SDZ038>040-052>056- 060>062-066-067. MN...FREEZING FOG ADVISORY UNTIL 4 AM FOR MNZ089-097-098. IA...FREEZING FOG ADVISORY UNTIL 4 AM FOR IAZ001>003-012>014- 020>022-032. NE...NONE. && $$ JH sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 1240 AM EST FRI JAN 26 2007 .UPDATE...AVIATION. && .AVIATION /05Z-24Z/... BANDS OF MVFR CLOUDS AND SNOW SHOWERS EXPECTED IN THE WEST. LOCALIZED BRIEF PERIODS OF IFR CONDITIONS IN HEAVIER SNOW SHOWER EARLY THIS MORNING. SNOW SHOWERS AND SNOW FLURRIES WILL END THIS MORNING...CONDITIONS WILL IMPROVE TO VFR THIS AFTERNOON IN THE WEST. IN THE EAST...VFR CONDITIONS EXPECTED DURING THE PERIOD. MOUNTAIN OBSCURATIONS ARE POSSIBLE IN THE WEST THIS MORNING. && .PREV DISCUSSION... /ISSUED 1152 PM EST THU JAN 25 2007/ UPDATE... SHORT TERM /REST OF TONIGHT/... RADAR CONTINUES TO SHOW FAIRLY STRONG SNOW BANDS EXTENDING ACROSS WV AND INTO SE OHIO. THESE BANDS WILL KEEP BRINGING AT LEAST MODERATE SNOW TO WESTERN GREENBRIER...AND LIGHTER SNOW FURTHER EAST. I HAVE MADE SOME QUICK ADJUSTMENTS TO THE SNOW AND WEATHER GRIDS TO SHOW MORE SNOW FOR THE NEXT 4 HOURS...AND MINOR ADJUSTMENTS TO WINDS AND TEMPERATURES. EXPECTING AN ADDITIONAL 2 TO 4 INCHES IN THAT SMALL PORTION OF THE COUNTY...SO WILL JUST KEEP THE ADVISORY GOING. HAVE HAD REPORTS OF 6 TO 9 INCHES OF SNOW ON THE WESTERN SLOPES IN WESTERN GREENBRIER. AN UPDATED WSW WILL BE ISSUED SOON. PREV DISCUSSION... /ISSUED 851 PM EST THU JAN 25 2007/ SHORT TERM /REST OF TONIGHT/... UPPER TROF PIVOTING ACROSS THE AREA PER VAPOR LOOP WILL CONTINUE TO PASS EAST OVERNIGHT. THIS SHOULD ALLOW MOISTURE TO SLOWLY DECREASE ESPCLY AFTER MIDNIGHT WITH LINGERING -SHSN FINALLY FADING LATE ACROSS THE NW PER LATEST WRF/RUC OUTPUT. HOWEVER APPEARS NARROW BANDED SHSN WILL LINGER A WHILE LONGER SW VA/SE WVA GIVEN STRONG/DEEP UNIDIRECTIONAL NW FLOW SEEN IN 00Z RNK RAOB. THUS PLAN TO LEAVE WINTER WX ADVISORY IN PLACE AT LEAST A FEW MORE HOURS TO ALLOW ANY ACCUMULATING -SHSN TO DIMINISH TO FLURRIES. OTRW WILL CONTINUE WITH OVERALL LIKELY POPS FAR NW AND CUT TO CHANCE OR JUST FLURRIES ELSEWHERE OVER THE RIDGES...AND MAINLY PC/CLEAR OUT EAST IN DOWNSLOPE FLOW. AS RH DECREASES BEHIND DEPARTING VORT ALSO EXPECT SOME SURGE IN WINDS ESPCLY SW VA GIVEN COLD ADVECTION...BUT MAY BE MARGINAL ADVISORY GIVEN RATHER WEAK PRES RISES. THIS MAY ALSO MAKE REACHING WIND CHILL VALUES IFFY (OUTSIDE OF THE MOUNTAIN TOP AT HSP) AS TEMPS RATHER SLOW TO FALL AND EXPECT MAY NOT REACH GOING LOWS UNDER CLOUDS/MIXING AS BEST COLD AIR PASSES NORTH. THEREFORE RAISING LOWS A LITTLE...BUT MAINTAINING WIND/CHILL ADVISORIES FOR NOW SINCE COLDER AIR ALOFT/STRONGEST WINDS DONT ARRIVE UNTIL ABOUT 06Z. PREV DISCUSSION... /ISSUED 724 PM EST THU JAN 25 2007/ UPDATE... WITH SNOW SHOWERS HAVING DIMINISHED ACROSS NW NC AND GRAYSON CTY VA WILL SEND A QUICK UPDATE TO DROP THESE AREAS FROM THE WINTER WX ADVISORY OVERNIGHT. OTRW HOLDING ADVISORY IN PLACE ELSEWHERE GIVEN CONTINUING BANDS OF SNOW SHOWERS. ALSO FEW OTHER CHANGES OTHER THAN TO LOWER POPS AS WELL ACROSS THE SW ZONES. PREV DISCUSSION... /ISSUED 654 PM EST THU JAN 25 2007/ AVIATION /00Z-24Z/... BANDED HEAVIER SNOW SHOWERS CONTINE ALONG AND WEST OF THE BLUE RIDGE...AND EXPECT THESE WILL CONTINUE FOR THE NEXT FEW HOURS AS LOW LEVEL LAPSE RATES REMAIN STEEP WITH CONTINUED INFLUX OF COLD AIR. MVFR CONDITONS EXPECTED ACRS THE FAR WEST...WITH LOCALIZED BRIEF PERIODS OF IFR IN HEAVIER SNOW...TRANSITIONING TO VFR STRATOCU CLOUD DECK ACRS MOST OF THE MOUNTAINS AND CLEAR CONDITIONS OUT EAST. THINGS SHOULD BEGIN TO WIND DOWN OVERNIGHT AS COLD ADVECTION WANES AND SFC RIDGING ATTEMPS TO POKE INTO THE REGION. WINDS WILL REMAIN QUITE GUSTY FOR MOST AREAS AS SECONDARY PUSH OF COLD ADVECTION ARRIVES PRIOR TO 06Z...LIKELY DECREASING EAST OF THE MOUNTAINS LATE TONIGHT AS SFC RIDGING WINS OUT. A RETURN TO VFR ALL AREAS TOMORROW MORNING...THOUGH STRATOCU DECK MAY LINGER ACRS THE FAR WEST INTO EARLY AFTN. PREV DISCUSSION... /ISSUED 231 PM EST THU JAN 25 2007/ SHORT TERM /TONIGHT THROUGH SUNDAY/... KEEPING THE CURRENT ADVISORIES GOING...AS SNOW SHOWERS WILL PERIST SEEING UPSTREAM BANDS INTO OH/IN. WINDS WILL ALSO BE A FACTOR...AND AS TEMPS DROP INTO THE TEENS TONIGHT...WIND CHILLS WILL DROP BELOW ZERO. SNOW SHOWERS SHOULD START TAPERING OFF TOWARD MORNING...AS LOW LVL MOISTURE SHRINKS...AND RIDGING BUILDS IN FROM THE SOUTHWEST. HIGH PRESSURE WILL CONTINUE WORKING IN FROM THE SOUTHWEST FRIDAY WITH WINDS DIMINISHING. BUMPED HIGHS UP SOME AS SKIES SHOULD CLEAR ENOUGH WITH WAA. STILL A CHILLY DAY. A NORTHERN STREAM SYSTEM WILL BRING RETURN OF CLOUDS TO THE NRN PORTION OF THE AREA SATURDAY...WITH A SMALL CHANCE OF RW/SW. WITH A WESTERLY FLOW BETWEEN THIS LOW MOVING ACROSS THE NORTHEAST AND HIGH PRESSURE OFF THE SOUTHEAST COAST WILL WARM TEMPS UP INTO THE 50S OUT EAST. SOUTHERN STREAM LOW WILL HANG ALONG THE GULF COAST AND NOT PHASE WITH THIS NRN STREAM WAVE. FRONT COMING THROUGH LOOKS TO PRODUCE A WEAK WAVE OF LOW PRESSURE OVER VA SAT NIGHT. LOOKING AT MAINLY CHANCES OF SNOW IN THE WESTERN FORECAST...AS THE WEST FLOW DRIES THINGS OUT A BIT. FLOW GOES NW BEHIND THIS SYSTEM SUNDAY AND WE GET INTO THE SNOW SHOWER REGIME THAT LASTS INTO SUNDAY NIGHT. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... OUR AREA WILL CONTINUE TO BE DOMINATED BY A TROUGH IN THE EAST...WITH SHOT OF COLD AIR BEHIND 2-3 CLIPPER SYSTEMS. THE FIRST SYSTEM WILL BE MOVING PAST BY THE BEGINNING OF THIS PERIOD WITH SNOW SHOWERS IN THE MOUNTAINS. THE NEXT CLIPPER ARRIVES TUESDAY AND ANOTHER THURSDAY. EACH ONE WILL BRING A CHANCE OF SNOW TO THE WESTERN FORECAST AREA...BUT THE MAIN ENERGY WITH THESE SYSTEMS WILL STAY WELL NORTH...SO NOT EXPECTING TO GET MUCH INFLUX OF MOISTURE TO BRING SIGNIFICANT PRECIP. AVIATION /18Z-18Z/... SNOW SQUALLS IN THE WEST WILL CONTINUE TO RESULT IN HIGHLY VARYING VSBYS THRU THE AFTN AND EARLY EVENING...WHILE CIGS REMAIN MOSTLY IN THE MVFR CATEGORY. IN THE EAST SCTD FLURRIES SHUD NOT PRODUCE LOWER THAN BRIEF 5SM VSBYS...NOT WORTH MENTIONING IN THE TAFS. NORTHWEST WINDS WILL BE QUITE STRONG...GUSTING BETWEEN 20 AND 30 KTS AT TIMES THRU THE EARLY EVENING. MVFR CIGS WILL BE SLOW TO LIFT AT BLF/LWB UNTIL MIDDAY TMRW. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND CHILL ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR VAZ007-009>011-015-018>020. WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR VAZ015. WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR VAZ007-009-010. NC...WIND CHILL ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NCZ001-018. WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR NCZ001-018. WV...WIND CHILL ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR WVZ042>045. WINTER WEATHER ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR WVZ042-043-045. && $$ UPDATE... AVIATION...07 va AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BLACKSBURG VA 1152 PM EST THU JAN 25 2007 .UPDATE... && .SHORT TERM /REST OF TONIGHT/... RADAR CONTINUES TO SHOW FAIRLY STRONG SNOW BANDS EXTENDING ACROSS WV AND INTO SE OHIO. THESE BANDS WILL KEEP BRINGING AT LEAST MODERATE SNOW TO WESTERN GREENBRIER...AND LIGHTER SNOW FURTHER EAST. I HAVE MADE SOME QUICK ADJUSTMENTS TO THE SNOW AND WEATHER GRIDS TO SHOW MORE SNOW FOR THE NEXT 4 HOURS...AND MINOR ADJUSTMENTS TO WINDS AND TEMPERATURES. EXPECTING AN ADDITIONAL 2 TO 4 INCHES IN THAT SMALL PORTION OF THE COUNTY...SO WILL JUST KEEP THE ADVISORY GOING. HAVE HAD REPORTS OF 6 TO 9 INCHES OF SNOW ON THE WESTERN SLOPES IN WESTERN GREENBRIER. AN UPDATED WSW WILL BE ISSUED SOON. && .PREV DISCUSSION... /ISSUED 851 PM EST THU JAN 25 2007/ SHORT TERM /REST OF TONIGHT/... UPPER TROF PIVOTING ACROSS THE AREA PER VAPOR LOOP WILL CONTINUE TO PASS EAST OVERNIGHT. THIS SHOULD ALLOW MOISTURE TO SLOWLY DECREASE ESPCLY AFTER MIDNIGHT WITH LINGERING -SHSN FINALLY FADING LATE ACROSS THE NW PER LATEST WRF/RUC OUTPUT. HOWEVER APPEARS NARROW BANDED SHSN WILL LINGER A WHILE LONGER SW VA/SE WVA GIVEN STRONG/DEEP UNIDIRECTIONAL NW FLOW SEEN IN 00Z RNK RAOB. THUS PLAN TO LEAVE WINTER WX ADVISORY IN PLACE AT LEAST A FEW MORE HOURS TO ALLOW ANY ACCUMULATING -SHSN TO DIMINISH TO FLURRIES. OTRW WILL CONTINUE WITH OVERALL LIKELY POPS FAR NW AND CUT TO CHANCE OR JUST FLURRIES ELSEWHERE OVER THE RIDGES...AND MAINLY PC/CLEAR OUT EAST IN DOWNSLOPE FLOW. AS RH DECREASES BEHIND DEPARTING VORT ALSO EXPECT SOME SURGE IN WINDS ESPCLY SW VA GIVEN COLD ADVECTION...BUT MAY BE MARGINAL ADVISORY GIVEN RATHER WEAK PRES RISES. THIS MAY ALSO MAKE REACHING WIND CHILL VALUES IFFY (OUTSIDE OF THE MOUNTAIN TOP AT HSP) AS TEMPS RATHER SLOW TO FALL AND EXPECT MAY NOT REACH GOING LOWS UNDER CLOUDS/MIXING AS BEST COLD AIR PASSES NORTH. THEREFORE RAISING LOWS A LITTLE...BUT MAINTAINING WIND/CHILL ADVISORIES FOR NOW SINCE COLDER AIR ALOFT/STRONGEST WINDS DONT ARRIVE UNTIL ABOUT 06Z. PREV DISCUSSION... /ISSUED 724 PM EST THU JAN 25 2007/ UPDATE... WITH SNOW SHOWERS HAVING DIMINISHED ACROSS NW NC AND GRAYSON CTY VA WILL SEND A QUICK UPDATE TO DROP THESE AREAS FROM THE WINTER WX ADVISORY OVERNIGHT. OTRW HOLDING ADVISORY IN PLACE ELSEWHERE GIVEN CONTINUING BANDS OF SNOW SHOWERS. ALSO FEW OTHER CHANGES OTHER THAN TO LOWER POPS AS WELL ACROSS THE SW ZONES. PREV DISCUSSION... /ISSUED 654 PM EST THU JAN 25 2007/ AVIATION /00Z-24Z/... BANDED HEAVIER SNOW SHOWERS CONTINE ALONG AND WEST OF THE BLUE RIDGE...AND EXPECT THESE WILL CONTINUE FOR THE NEXT FEW HOURS AS LOW LEVEL LAPSE RATES REMAIN STEEP WITH CONTINUED INFLUX OF COLD AIR. MVFR CONDITONS EXPECTED ACRS THE FAR WEST...WITH LOCALIZED BRIEF PERIODS OF IFR IN HEAVIER SNOW...TRANSITIONING TO VFR STRATOCU CLOUD DECK ACRS MOST OF THE MOUNTAINS AND CLEAR CONDITIONS OUT EAST. THINGS SHOULD BEGIN TO WIND DOWN OVERNIGHT AS COLD ADVECTION WANES AND SFC RIDGING ATTEMPS TO POKE INTO THE REGION. WINDS WILL REMAIN QUITE GUSTY FOR MOST AREAS AS SECONDARY PUSH OF COLD ADVECTION ARRIVES PRIOR TO 06Z...LIKELY DECREASING EAST OF THE MOUNTAINS LATE TONIGHT AS SFC RIDGING WINS OUT. A RETURN TO VFR ALL AREAS TOMORROW MORNING...THOUGH STRATOCU DECK MAY LINGER ACRS THE FAR WEST INTO EARLY AFTN. PREV DISCUSSION... /ISSUED 231 PM EST THU JAN 25 2007/ SHORT TERM /TONIGHT THROUGH SUNDAY/... KEEPING THE CURRENT ADVISORIES GOING...AS SNOW SHOWERS WILL PERIST SEEING UPSTREAM BANDS INTO OH/IN. WINDS WILL ALSO BE A FACTOR...AND AS TEMPS DROP INTO THE TEENS TONIGHT...WIND CHILLS WILL DROP BELOW ZERO. SNOW SHOWERS SHOULD START TAPERING OFF TOWARD MORNING...AS LOW LVL MOISTURE SHRINKS...AND RIDGING BUILDS IN FROM THE SOUTHWEST. HIGH PRESSURE WILL CONTINUE WORKING IN FROM THE SOUTHWEST FRIDAY WITH WINDS DIMINISHING. BUMPED HIGHS UP SOME AS SKIES SHOULD CLEAR ENOUGH WITH WAA. STILL A CHILLY DAY. A NORTHERN STREAM SYSTEM WILL BRING RETURN OF CLOUDS TO THE NRN PORTION OF THE AREA SATURDAY...WITH A SMALL CHANCE OF RW/SW. WITH A WESTERLY FLOW BETWEEN THIS LOW MOVING ACROSS THE NORTHEAST AND HIGH PRESSURE OFF THE SOUTHEAST COAST WILL WARM TEMPS UP INTO THE 50S OUT EAST. SOUTHERN STREAM LOW WILL HANG ALONG THE GULF COAST AND NOT PHASE WITH THIS NRN STREAM WAVE. FRONT COMING THROUGH LOOKS TO PRODUCE A WEAK WAVE OF LOW PRESSURE OVER VA SAT NIGHT. LOOKING AT MAINLY CHANCES OF SNOW IN THE WESTERN FORECAST...AS THE WEST FLOW DRIES THINGS OUT A BIT. FLOW GOES NW BEHIND THIS SYSTEM SUNDAY AND WE GET INTO THE SNOW SHOWER REGIME THAT LASTS INTO SUNDAY NIGHT. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... OUR AREA WILL CONTINUE TO BE DOMINATED BY A TROUGH IN THE EAST...WITH SHOT OF COLD AIR BEHIND 2-3 CLIPPER SYSTEMS. THE FIRST SYSTEM WILL BE MOVING PAST BY THE BEGINNING OF THIS PERIOD WITH SNOW SHOWERS IN THE MOUNTAINS. THE NEXT CLIPPER ARRIVES TUESDAY AND ANOTHER THURSDAY. EACH ONE WILL BRING A CHANCE OF SNOW TO THE WESTERN FORECAST AREA...BUT THE MAIN ENERGY WITH THESE SYSTEMS WILL STAY WELL NORTH...SO NOT EXPECTING TO GET MUCH INFLUX OF MOISTURE TO BRING SIGNIFICANT PRECIP. AVIATION /18Z-18Z/... SNOW SQUALLS IN THE WEST WILL CONTINUE TO RESULT IN HIGHLY VARYING VSBYS THRU THE AFTN AND EARLY EVENING...WHILE CIGS REMAIN MOSTLY IN THE MVFR CATEGORY. IN THE EAST SCTD FLURRIES SHUD NOT PRODUCE LOWER THAN BRIEF 5SM VSBYS...NOT WORTH MENTIONING IN THE TAFS. NORTHWEST WINDS WILL BE QUITE STRONG...GUSTING BETWEEN 20 AND 30 KTS AT TIMES THRU THE EARLY EVENING. MVFR CIGS WILL BE SLOW TO LIFT AT BLF/LWB UNTIL MIDDAY TMRW. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND CHILL ADVISORY UNTIL 6 AM EST FRIDAY FOR VAZ007-009>011- 015-018>020. WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR VAZ015. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR VAZ007-009- 010. NC...WIND CHILL ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ001-018. WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ001-018. WV...WIND CHILL ADVISORY UNTIL 6 AM EST FRIDAY FOR WVZ042>045. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR WVZ042-043- 045. && $$ UPDATE... SHORT TERM...JJ va AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BLACKSBURG VA 851 PM EST THU JAN 25 2007 .SHORT TERM /REST OF TONIGHT/... UPPER TROF PIVOTING ACROSS THE AREA PER VAPOR LOOP WILL CONTINUE TO PASS EAST OVERNIGHT. THIS SHOULD ALLOW MOISTURE TO SLOWLY DECREASE ESPCLY AFTER MIDNIGHT WITH LINGERING -SHSN FINALLY FADING LATE ACROSS THE NW PER LATEST WRF/RUC OUTPUT. HOWEVER APPEARS NARROW BANDED SHSN WILL LINGER A WHILE LONGER SW VA/SE WVA GIVEN STRONG/DEEP UNIDIRECTIONAL NW FLOW SEEN IN 00Z RNK RAOB. THUS PLAN TO LEAVE WINTER WX ADVISORY IN PLACE AT LEAST A FEW MORE HOURS TO ALLOW ANY ACCUMULATING -SHSN TO DIMINISH TO FLURRIES. OTRW WILL CONTINUE WITH OVERALL LIKELY POPS FAR NW AND CUT TO CHANCE OR JUST FLURRIES ELSEWHERE OVER THE RIDGES...AND MAINLY PC/CLEAR OUT EAST IN DOWNSLOPE FLOW. AS RH DECREASES BEHIND DEPARTING VORT ALSO EXPECT SOME SURGE IN WINDS ESPCLY SW VA GIVEN COLD ADVECTION...BUT MAY BE MARGINAL ADVISORY GIVEN RATHER WEAK PRES RISES. THIS MAY ALSO MAKE REACHING WIND CHILL VALUES IFFY (OUTSIDE OF THE MOUNTAIN TOP AT HSP) AS TEMPS RATHER SLOW TO FALL AND EXPECT MAY NOT REACH GOING LOWS UNDER CLOUDS/MIXING AS BEST COLD AIR PASSES NORTH. THEREFORE RAISING LOWS A LITTLE...BUT MAINTAINING WIND/CHILL ADVISORIES FOR NOW SINCE COLDER AIR ALOFT/STRONGEST WINDS DONT ARRIVE UNTIL ABOUT 06Z. && .PREV DISCUSSION... /ISSUED 724 PM EST THU JAN 25 2007/ UPDATE... WITH SNOW SHOWERS HAVING DIMINISHED ACROSS NW NC AND GRAYSON CTY VA WILL SEND A QUICK UPDATE TO DROP THESE AREAS FROM THE WINTER WX ADVISORY OVERNIGHT. OTRW HOLDING ADVISORY IN PLACE ELSEWHERE GIVEN CONTINUING BANDS OF SNOW SHOWERS. ALSO FEW OTHER CHANGES OTHER THAN TO LOWER POPS AS WELL ACROSS THE SW ZONES. PREV DISCUSSION... /ISSUED 654 PM EST THU JAN 25 2007/ AVIATION /00Z-24Z/... BANDED HEAVIER SNOW SHOWERS CONTINE ALONG AND WEST OF THE BLUE RIDGE...AND EXPECT THESE WILL CONTINUE FOR THE NEXT FEW HOURS AS LOW LEVEL LAPSE RATES REMAIN STEEP WITH CONTINUED INFLUX OF COLD AIR. MVFR CONDITONS EXPECTED ACRS THE FAR WEST...WITH LOCALIZED BRIEF PERIODS OF IFR IN HEAVIER SNOW...TRANSITIONING TO VFR STRATOCU CLOUD DECK ACRS MOST OF THE MOUNTAINS AND CLEAR CONDITIONS OUT EAST. THINGS SHOULD BEGIN TO WIND DOWN OVERNIGHT AS COLD ADVECTION WANES AND SFC RIDGING ATTEMPS TO POKE INTO THE REGION. WINDS WILL REMAIN QUITE GUSTY FOR MOST AREAS AS SECONDARY PUSH OF COLD ADVECTION ARRIVES PRIOR TO 06Z...LIKELY DECREASING EAST OF THE MOUNTAINS LATE TONIGHT AS SFC RIDGING WINS OUT. A RETURN TO VFR ALL AREAS TOMORROW MORNING...THOUGH STRATOCU DECK MAY LINGER ACRS THE FAR WEST INTO EARLY AFTN. PREV DISCUSSION... /ISSUED 231 PM EST THU JAN 25 2007/ SHORT TERM /TONIGHT THROUGH SUNDAY/... KEEPING THE CURRENT ADVISORIES GOING...AS SNOW SHOWERS WILL PERIST SEEING UPSTREAM BANDS INTO OH/IN. WINDS WILL ALSO BE A FACTOR...AND AS TEMPS DROP INTO THE TEENS TONIGHT...WIND CHILLS WILL DROP BELOW ZERO. SNOW SHOWERS SHOULD START TAPERING OFF TOWARD MORNING...AS LOW LVL MOISTURE SHRINKS...AND RIDGING BUILDS IN FROM THE SOUTHWEST. HIGH PRESSURE WILL CONTINUE WORKING IN FROM THE SOUTHWEST FRIDAY WITH WINDS DIMINISHING. BUMPED HIGHS UP SOME AS SKIES SHOULD CLEAR ENOUGH WITH WAA. STILL A CHILLY DAY. A NORTHERN STREAM SYSTEM WILL BRING RETURN OF CLOUDS TO THE NRN PORTION OF THE AREA SATURDAY...WITH A SMALL CHANCE OF RW/SW. WITH A WESTERLY FLOW BETWEEN THIS LOW MOVING ACROSS THE NORTHEAST AND HIGH PRESSURE OFF THE SOUTHEAST COAST WILL WARM TEMPS UP INTO THE 50S OUT EAST. SOUTHERN STREAM LOW WILL HANG ALONG THE GULF COAST AND NOT PHASE WITH THIS NRN STREAM WAVE. FRONT COMING THROUGH LOOKS TO PRODUCE A WEAK WAVE OF LOW PRESSURE OVER VA SAT NIGHT. LOOKING AT MAINLY CHANCES OF SNOW IN THE WESTERN FORECAST...AS THE WEST FLOW DRIES THINGS OUT A BIT. FLOW GOES NW BEHIND THIS SYSTEM SUNDAY AND WE GET INTO THE SNOW SHOWER REGIME THAT LASTS INTO SUNDAY NIGHT. LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... OUR AREA WILL CONTINUE TO BE DOMINATED BY A TROUGH IN THE EAST...WITH SHOT OF COLD AIR BEHIND 2-3 CLIPPER SYSTEMS. THE FIRST SYSTEM WILL BE MOVING PAST BY THE BEGINNING OF THIS PERIOD WITH SNOW SHOWERS IN THE MOUNTAINS. THE NEXT CLIPPER ARRIVES TUESDAY AND ANOTHER THURSDAY. EACH ONE WILL BRING A CHANCE OF SNOW TO THE WESTERN FORECAST AREA...BUT THE MAIN ENERGY WITH THESE SYSTEMS WILL STAY WELL NORTH...SO NOT EXPECTING TO GET MUCH INFLUX OF MOISTURE TO BRING SIGNIFICANT PRECIP. AVIATION /18Z-18Z/... SNOW SQUALLS IN THE WEST WILL CONTINUE TO RESULT IN HIGHLY VARYING VSBYS THRU THE AFTN AND EARLY EVENING...WHILE CIGS REMAIN MOSTLY IN THE MVFR CATEGORY. IN THE EAST SCTD FLURRIES SHUD NOT PRODUCE LOWER THAN BRIEF 5SM VSBYS...NOT WORTH MENTIONING IN THE TAFS. NORTHWEST WINDS WILL BE QUITE STRONG...GUSTING BETWEEN 20 AND 30 KTS AT TIMES THRU THE EARLY EVENING. MVFR CIGS WILL BE SLOW TO LIFT AT BLF/LWB UNTIL MIDDAY TMRW. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...WIND CHILL ADVISORY FROM 1 AM TO 6 AM EST FRIDAY FOR VAZ007- 009>011-015-018>020. WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR VAZ015. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR VAZ007-009- 010. NC...WIND CHILL ADVISORY FROM 1 AM TO 6 AM EST FRIDAY FOR NCZ001- 018. WIND ADVISORY UNTIL 6 AM EST FRIDAY FOR NCZ001-018. WV...WIND CHILL ADVISORY FROM 1 AM TO 6 AM EST FRIDAY FOR WVZ042>045. WINTER WEATHER ADVISORY UNTIL 6 AM EST FRIDAY FOR WVZ042-043- 045. && $$ UPDATE... SHORT TERM...10 va AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 132 AM EST SAT JAN 27 2007 .AVIATION /06Z-06Z/... A WEAK SURFACE LOW CURRENTLY OVER SOUTHERN MICHIGAN WILL MOVE ACROSS THE AREA THIS AFTERNOON. WITH ONLY WEAK LIFT ASSOCIATED WITH THIS FEATURE PRECIP WILL BE LIMITED AND COULD EITHER BE SPOTTY FREEZING DRIZZLE OR LIGHT SNOW. IN GENERAL CONDITIONS THROUGH THE PERIOD WILL BE MVFR DUE TO CIGS, EXCEPT AT KAVP WHERE VFR MAY PREVAIL. CIGS WILL LOWER OVERNIGHT WITH VSBY RESTRICTIONS TO IFR AT KSYR BTW 14Z-18Z DUE TO LIGHT SNOW AND FOG. THIS MAY NEED TO BE ADJUSTED TO INCLUDE FREEZING DRIZZLE, IF CONDITIONS BECOME MORE WIDESPREAD UPSTREAM. MODEL SOUNDINGS DUE SHOW THE POTENTIAL FOR THIS PRECIP TYPE. MVFR VSBY RESTRICTIONS DUE TO FOG ARE ALSO EXPECTED AT KTIH/KBGM BTW 14Z-18Z. WINDS WILL REMAIN BTW 5-10 KNOTS, PRIMARILY SOUTHEAST EARLY THIS MORNING THEN SOUTHERLY BY MID MORNING SHIFTING TO SOUTHWEST EARLY THIS AFTERNOON TO WESTERLY TOWARD EVENING. RRM && .PREV DISCUSSION... /ISSUED 746 PM EST FRI JAN 26 2007/ SHORT TERM /REST OF TONIGHT/... MAY DO ANOTHER UPDATE PRIOR TO SHIFT CHANGE. FOR NOW WE HAVE A BIG UPDATE TO TEMPS FOR EASTERN PORTIONS OF REGION, AS AREA FROM NORTHERN ONEIDA SOUTH TOWARD OTSEGO IS AT OR BELOW ZERO. WE USED RUC TEMPS, MODIFIED BY CURRENT MESO OBS, AS A BEST GUESS AT TREND. ALSO TWEAKED TIMING OF PRECIP WHICH HAS ARRIVED SOONER THAN ANTICIPATED IN THE FINGER LAKES. DJP PREV DISCUSSION... /ISSUED 331 PM EST FRI JAN 26 2007/ SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... VIS IMAGERY SHOWS SHALLOW LAKE EFFECT SNOW SHWRS AND CLDS FROM NW-SE ACRS CWA AS MID-HI CLDS FROM NEXT WAVE OVERSPREAD WRN NY/AND MUCH OF WRN AND SRN PA. THIS NEXT WAVE WAS LEADG TO A WAA SUPPORTED SHIELD OF SNOWS WHICH ARE PROJECTED TO DRY UP SOME AS IT TRACKS E TONIGHT. ACC/S WILL BE LESS THAN ONE INCH AS THE SYSTEM REALLY LACKS MOISTURE. AFTER THE DEEPER WAA PASSES E...THERE IS STILL SHALLOW MOISTURE LEFT OVER AFTER MAIN SNOWS AND WAA PASS E AND DIMINISH LATER TONIGHT. SEE POTENTIAL FOR A LITTLE PATCHY FZDZ FOR A FEW HOURS AFTER MAIN SHIELD OF LIGHT SNOWS DRY UP AS IT WORKS E LATER TONIGHT. FOR SAT...SKIES WILL REMAIN CLDY WITH A LL MOISTURE FEED ACRS MOST OF CWA AND LEAD TO LIGHT SNOWS AND FLURRIES MUCH OF THE DAY. NOT MUCH IN THE WAY OF ACC/S EXPECTED. CLIPPER DROPS THRU FA SAT EVENING WITH FRONT DRAPED ACROSS UPSTATE NY BACK THRU LK MI. FRONT WILL MOVE THROUGH SUN NIGHT/MON MORNING. BOTH GFS AND WRF ADVERTISE WAVE DEVELOPING ALONG THE FRONT SUN NIGHT TO HELP PULL IT THRU. THIS PORTION OF SHORT TERM STILL UP IN THE AIR IN REGARD TO WHEN BEST PCPN CHCS WILL BE. ONCE FNT PASSES...LAKE EFFECT POSSIBLE THRU END OF THE SHORT TERM...ESPECIALLY MONDAY AND MONDAY NIGHT ACROSS FAVORED AREAS AFTER DEEP H5 TROF PASSES EAST. TEMPS WILL CONTINUE TO RUN SLIGHTLY BLO NORMAL AS TROF REMAINS OVER NORTHEAST AND HIGH AMPLITUDE RIDGE BUILDS OVER WEST COAST. LONG TERM /TUESDAY THROUGH FRIDAY/... COLD PATTERN WILL CONTINUE WITH CLOUDS AND SNOW SHOWERS OFF THE LAKES AND AN OCCASIONAL WEAK DISTURBANCE OR REINFORCING COLD WAVE MOVING THROUGH. ON TUESDAY...WEAK LOW PRES AREA WILL MOVE ACROSS THE LAKES AND NEW YORK BRINGING A CHANCE OF SNOW SHOWERS AND FLURRIES. HIGH PRES CENTER WILL PASS ACROSS PA ON WED WITH WLY WINDS OFF THE LAKES. ANOTHER LOW PRES AREA MOVES ACROSS THE LAKES INTO SE CANADA THU BRINGING ANOTHER COLD FRONT THROUGH NY AND PA THU NIGHT WITH SNOW SHOWERS POSSIBLE. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. && $$ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 1018 PM PST FRI JAN 26 2007 .SYNOPSIS...HIGH PRESSURE WILL PERSIST THROUGH EARLY NEXT WEEK RESULTING IN A DRY AND STABLE WEATHER PATTERN. AREAS OF LOW CLOUDS AND FOG WILL PERSIST TONIGHT...BUT DRIER AIR MOVING IN FROM THE NORTH WILL BEGIN TO DECREASE THIS COVERAGE THROUGH THE WEEKEND. && .DISCUSSION... UPDATED THE FORECAST TO ADJUST FOR OVERNIGHT LOWS AND CLOUD/FOG COVER OVERNIGHT. REX BLOCK HOLDING STRONG ALOFT WHILE A WEAK SHORTWAVE TROUGH DROPPED EAST OF THE CONTINENTAL DIVIDE. HIGH PRESSURE RESIDES NORTH OF THE BC BORDER...ENHANCING NORTHERLY FLOW ESPECIALLY DOWN THE OKANOGAN VALLEY. THIS HAS CLEARED THE STRATUS AND FOG AND ALLOWED DEWPOINTS TO DROP ACROSS MUCH OF OKANOGAN... FERRY...DOUGLAS AND MUCH OF CHELAN COUNTIES. MEANWHILE...STRATUS AND FOG CONTINUES TO PLAGUE ELEVATIONS BELOW 3500 FEET. THE HIGH PRESSURE CELL WILL SHIFT EAST AND HELP GENERATE A NORTHEAST FLOW ACROSS NORTH IDAHO. THIS CAN BE SEEN DEVELOPING WITH SPOTTY CLEARING TAKING PLACE FROM SANDPOINT TO COEUR D`ALENE. THE NAM...RUC AND GFS SHOW THIS TREND CONTINUING THROUGH THE NIGHT AS THE DRIER AIR SEEPS INTO THE REGION. THE PROBLEM IS THE TIME OF THE NIGHT AS IT BATTLES THE DIURNALLY FAVORED TIME FOR FOG DEVELOPMENT. WILL ANTICIPATE GRADUAL IMPROVEMENT IN THE NE VALLEYS...WHILE THE STRATUS AND LCL FOG WILL HOLD TIGHT ACROSS MUCH OF THE BASIN...PALOUSE...LEWISTON AND WENATCHEE AREAS. ADJUSTED LOWS WITH SIMILAR IF NOT SLIGHTLY LOWER READINGS THAN SEEN LAST NIGHT IN THE CLEARED OUT NRN VALLEYS. RFOX. && .AVIATION...AGAIN...THE BIG CONCERN WILL BE THE STRATUS AND FOG ACROSS MANY LOWER ELEVATIONS SITES. THESE LOW CLOUDS WILL GRADUAL ERODE OR IMPROVE TONIGHT INTO SAT MORNING AS DRIER AIR CONTINUES TO FILTER SOUTH THROUGH THE OKANOGAN VALLEY AND THE PURCELL TRENCH. COMPLICATING MATTERS IS THE CONTINUED VERY MOIST LOW LEVELS IN THESE AREAS. THUS...IF THE STRATUS LAYER DOES BREAK UP OR SHIFT SOUTH...GROUND FOG COULD DEVELOP QUICKLY RESULTING IN IFR CIGS AND VSBYS IN THIS AREA FOR A BRIEF PERIOD BEFORE 14Z. DRIER AIR FILTERING THROUGH THE PURCELL TRENCH SHOULD CLEAR OUT KGEG/KSFF/KCOE BTWN 10-14Z. DOWNSLOPING EASTERLY FLOW WILL HELP ERODE THE STRATUS/FOG FROM KPUW AND KLWS BEFORE 18Z...MEANWHILE KMWH AND FINALLY KEAT WILL SHOW SOME CLEARING FROM THE NORTH- NORTHEAST FLOW BY 18Z AS WELL. ONCE CONDS BECOME VFR BY EARLY AFTERNOON...THERE IS FAIR CONFIDENCE THEY SHOULD HOLD THROUGH 06Z SUN. RFOX. && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 22 33 17 34 18 31 / 0 0 0 0 0 0 COEUR D`ALENE 24 35 19 33 20 32 / 0 0 0 0 0 0 PULLMAN 22 33 19 33 20 34 / 0 0 0 0 0 0 LEWISTON 27 36 23 36 23 38 / 0 0 0 10 0 0 COLVILLE 20 38 17 35 17 29 / 0 0 0 0 0 0 SANDPOINT 20 35 16 33 18 31 / 0 0 0 0 0 0 KELLOGG 20 33 17 32 18 30 / 0 0 0 0 0 0 MOSES LAKE 24 33 21 33 21 37 / 10 10 10 10 0 0 WENATCHEE 26 34 23 34 24 35 / 10 10 10 0 0 0 OMAK 23 38 20 36 18 33 / 0 0 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 702 AM MST SAT JAN 27 2007 .UPDATE...HAVE UPDATED FCST TO BOOST POPS SLIGHTLY OVER NRN PORTION OF CWA THIS MORN...AS BAND OF LIGHT SNOW HAS MOVED INTO THE AREA. SNOWFALL APPEARS TO BE RATHER LIGHT IN THIS FIRST BAND...AND MAY NOT EVEN ACCUMULATE IN THE SHORT TERM. HI-RES RUC AND LATEST NAM CONFINE MOST OF THE SNOWFALL TO EL PASO AND TELLER COUNTIES UNTIL AROUND 18Z. MAY SEE SOME MORE ISOLD SNOWFALL TO THE SOUTH THRU THIS MORNING. STILL LOOKS ON TARGET FOR A BETTER SHOT OF ACCUMULATIONS LATER THIS AFTERNOON AND EVE. ROSE && .PREV DISCUSSION... /ISSUED 333 AM MST SAT JAN 27 2007/ SHORT TERM... TODAY AND TONIGHT ..TIMING OF SNOW AND ACCUMULATIONS ARE MAIN SHORT TERM CHALLENGES... WV IMAGERY SHOWS SHRTWAV MOVING THRU NRN WY ATTM. LIGHT RADAR RETURNS HAVE BEEN SHOWING IN NERN PART OF CO...BUT OBS ARE INDICATING ONLY BKN-OVC DECKS AROUND 5K FT OR SO. SOME LOCAL LOWER CIGS APPEARING OVER THE PALMER. OBS MATCH UP PRETTY WELL WITH NAM FCST...SO HAVE GENERALLY FOLLOWED THE NAM FOR LATER TIMING BUT WENT WITH A NAM-GFS BLEND FOR AMTS. THIS PUTS BEST CHANCE OF PRECIP LATER THIS AFTERNOON THRU EVENING. HAVE THEREFORE CUT POPS BACK THIS MORN TO FALL IN LINE WITH MOS...WHICH IS ONLY ABOUT 10 PERCENT FOR MORNING POPS AT KCOS AND KMNH. MODELS HAVE BEEN PRETTY CONSISTENT WITH AMTS FROM THIS DISTURBANCE...AND SO HAVE ONLY TWEAKED ACCUMS THRU TONIGHT. AIR IS PRETTY COLD TO THE NORTH...MT SNDGS FROM 00Z SHOW AROUND MINUS 20 AT H7...SO WILL SEE HIGH SNOW RATIOS FROM WHATEVER FALLS. THE 1 TO 3 INCH RANGE STILL LOOKS REASONABLE...WITH SOME HIGHER AMTS OVER THE UPSLOPE REGIONS AND OVER THE SRN SANGRES/CULEBRA RANGE. WITH SLIGHTLY LATER TIMING...DEEP ENOUGH SATURATED LAYER SHOULD BE FAR ENOUGH BELOW FREEZING THAT IT DOES NOT LOOK LIKE FZNG PRECIP IS AN ISSUE...SHOULD BE ALL LIGHT SNOW. SYSTEM MOVES THRU FAIRLY QUICKLY AND SHOULD SEE PRECIP END FROM N TO S TONIGHT. 44 LONG TERM... SUNDAY THROUGH FRIDAY ..COLD WX WILL BE WITH US FOR AWHILE... NOT MUCH CHANGE IN THE FCST PATTERN THIS PERIOD. ALL LONG RANGE GUIDANCE INDICATES THE ARCTIC EXPRESS WILL BE RUNNING AT FULL FORCE THROUGH THIS FCST PERIOD. GUIDANCE CONTINUES TO INDICATE WAVE AFTER WAVE OF COLD WX WILL DIVE SOUTH OUT OF CANADA...WITH THE COLDEST WX MOVING INTO OUR REGION LATE IN THE WEEK INTO NEXT WEEKEND. WITH EACH WAVE...WE WILL HAVE A CHANCE OF LIGHT TO MODERATE FLUFFY SNOW. ALTHOUGH IT IS STIL A WEEK OFF...IT MUST BE EMPHASIZED THAT IF THE LONG RANGE GUIDANCE LATE NEXT WEEK VERIFIES...WE MAY SEE BRUTALLY COLD WX IN OUR REGION. CURRENTLY...OUR FCST FOR LATE WEEK HAS HIGHS IN THE 20S AND 30S...BUT THESE VALUES MAY LIKELY BE DROPPED DOWN DRAMATICALLY AS WE GET CLOSER TO THE EVENT. ATTM...IT DOES NOT APPEAR ANY BIG SNOW FALL EVENTS WILL OCCUR...BUT GIVEN GOOD DENDRITIC GROWTH POTENTIAL...WE MAY SEE LOTS OF FLUFFY SNOW WHICH MAY ACCUMULATE THROUGH THE WEEK. /34 PUB WATCHES/WARNINGS/ADVISORIES... NONE. $$ && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 44/34 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1110 AM EST SAT JAN 27 2007 .UPDATE...WEST NORTHWEST FLOW LAKE ENHANCED SNOWS RAPIDLY INCREASING IN COVERAGE AND INTENSITY OVER THE AREA AS MID LEVEL SHORTWAVE...AND ASSOCIATED POCKET OF MODERATE -DIVQ...APPROACH THE AREA. AT THE SURFACE...ELONGATED AREA OF LOW PRESSURE EXTENDS FROM NEAR BUFFALO NEW YORK UP THROUGH EASTERN LAKE SUPERIOR. MONTREAL RIVER CANADA RADAR SHOWING BEST CONVERGENCE ASSOCIATED WITH THIS LOW/SURFACE TROUGH REMAINING NORTH OF EASTERN UPPER AT THIS TIME. FORECAST CONCERNS REMAIN LAKE SNOW CHANCES AND AMOUNTS FOR THIS AFTERNOON. OVERALL LAKE EFFECT PARAMETERS PRETTY DECENT WITH 12Z GREEN BAY SOUNDING SHOWING NEARLY 7KFT INVERSION LEVEL AND MODEL GUIDANCE SHOWING 850MB-700MB MOISTURE VALUES OF >80 PERCENT. ONE LIMITING FACTOR...AT LEAST EARLY ON...REMAINS OVER WATER INSTABILITY WITH GREEN BAY SOUNDING SHOWING 850MB TEMPERATURES OF ONLY -8C...PRODUCING A CORRESPONDING DELTA T VALUE OF 10C. HOWEVER...CAA CONTINUES WITH APPROACH OF SHORTWAVE WITH LATEST RUC GUIDANCE SUGGESTING 16Z 850MB TEMPERATURES OF -11C OVER NORTHERN LAKE MICHIGAN AND -11C TO -13C OVER EASTERN LAKE SUPERIOR. THIS MATCHES NICELY WITH RECENT RADAR RETURNS SEEN ON LOCAL RADARS. SYNOPTIC SUPPORT ONLY INCREASES DURING THE AFTERNOON AS AFOREMENTIONED SHORTWAVE ROTATES OVER NORTHERN MICHIGAN. INVERSION LEVELS BECOME NEARLY NON EXISTENT (ACTUALLY AT TROPOPAUSE LEVEL OF 18KT) AND MID LEVEL MOISTURE REMAINS ABUNDANT. STILL...INSTABILITY LEVELS REMAIN MARGINAL WITH 850MB TEMPERATURES ONLY SLOWLY FALLING TO AROUND -12C TO -14C BY AFTERNOON. THIS SHOULD HELP LIMIT INTENSITY OF SNOW SHOWERS. EARLY FORECAST OF UP TO 3 INCHES NEAR THE LAKE SUPERIOR SHORELINE AND AN INCH OR TWO OVER FAVORED WEST NORTHWEST FLOW AREAS OF THE NORTHERN LOWER APPEARS ON TARGET. HOWEVER...WILL CLOSELY MONITOR ENHANCED CONVERGENT ZONE THAT IS EXPECTED TO DROP INTO THE EASTERN U.P. AS SURFACE TROUGH ROTATES DOWN WITH PASSAGE OF SHORTWAVE. IF BANDS CAN STAY FOCUSED LONG ENOUGH ALONG THIS FEATURE SNOWFALL AMOUNTS WILL LIKELY NEED TO BE INCREASED FOR PORTIONS OF CHIPPEWA COUNTY. OTHERWISE...ONLY SIGNIFICANT CHANGE FROM MORNING FORECAST WAS TO BUMP UP COVERAGE TO SCATTERED AND NUMEROUS OVER EASTERN SECTIONS OF THE FORECAST AREA BASED OFF RADAR RETURNS. WILL CONTINUE TO ANALYZE INCOMING DATA THIS AFTERNOON FOR A POSSIBLE UPGRADE TO AN ADVISORY OR WARNING FOR THOSE AREAS UNDER THE LAKE EFFECT SNOW WATCH TONIGHT AND SUNDAY. MSB && .PREV DISCUSSION...ISSUED AT 437 AM EST SAT JAN 27 2007 SFC WAVE SLOWLY SLIDING THROUGH THE WESTERN GREAT LAKES THIS MORNING...WITH A SECONDARY COLD FRONT AND THE LEADING EDGE OF SUBSTANTIALLY COLDER AIR TRAILING THROUGH THE UPPER MIDWEST/NRN PLAINS. WATER VAPOR IMAGERY REVEALING SHORT WAVE COMING RIGHT BEHIND PUSHING ACROSS LAKE SUPERIOR ATTM. 00Z UPPER AIR PLOTS REVEALING UPPER JET STREAK OVER BUFFALO LAST EVENING WHILE SECOND JET CORE ACROSS CENTRAL MN. CAN INFER WEAK JET COUPLING/UPPER DIVERGENCE ACROSS NRN MICHIGAN LAST EVENING...WHICH WITH COMBINED WITH LOW LEVEL CONVERGENCE ALONG THE SFC WAVE...MAY HAVE HELPED SPAWN OUR LITTLE FREEZING DRIZZLE STORM DURING MID-LATE EVENING HOURS. FZDZ HAD DIMINISHED AROUND MIDNIGHT ACROSS THE REGION...BUT HAVE SEEN ANOTHER FLARE UP ON KAPX RADAR AND HERE AT THE OFFICE OVERNIGHT (ALBEIT NOT NEARLY AS WIDESPREAD AND HEAVY AS LAST EVENING). INITIAL FORECAST CONCERN REVOLVES AROUND ONGOING WINTER WEATHER ADVISORY GOOD THROUGH 8 AM (COVERING FZDZ). THEN...ATTENTION TURNS TO A LAKE EFFECT EVENT LATER TODAY THROUGH SUNDAY AND HEADLINE POSSIBILITIES. TODAY...FIRST OFF WILL NEED TO ADDRESS ONGOING WSW. AS MENTIONED ABOVE...ANOTHER LIGHT FLARE UP OF -FZDZ MATERIALIZED OVERNIGHT PRIMARILY ACROSS THE HIGHER TERRAIN (AS USUAL) PER RADAR DATA AND SFC OBS. BUT LATEST RADAR TREND SUGGESTING -FZDZ AGAIN DWINDLING AND THINK WE CAN GET AWAY WITH CANCELLING THE WSW WITH MORNING ZONE ISSUANCE. ATTENTION THEN TURNS TO PRECIP AND LAKE EFFECT POTENTIAL FOR THE REST OF TODAY. DECENT MID LEVEL SHORT WAVE AND SHOT OF QG UPWARD FORCING FORECAST TO SLIDE THROUGH NRN MICHIGAN DURING THE AFTERNOON HOURS. MEANWHILE...SFC LOW SLIDES OFF TO THE EAST BUT WITH A VERY SHARP LOW LEVEL TROUGH HANGING BACK ACROSS LAKE HURON AND INTO EASTERN LAKE SUPERIOR. STRONG LOW LEVEL CONVERGENCE ALONG THIS TROUGH COUPLED WITH QG UPWARD FORCING MOVING THROUGH/GRADUALLY INCREASING OVER LAKE INSTABILITY (DELTA T/S INCREASING THROUGH THE TEENS)/AND ERODING INVERSION HEIGHTS WILL FOCUS BEST LAKE EFFECT SNOW SHOWERS ALONG THE NORTH SHORE OF THE UPPER PENINSULA FROM WHITEFISH POINT WESTWARD THIS AFTERNOON. BUT WITH THE MODEST LAKE-850 MB DELTA T/S WILL KEEP ACCUMULATIONS UNDER 3 INCHES FOR THE DAY GREATEST AMOUNTS FOCUSED AROUND WHITEFISH POINT. ACROSS NRN LOWER MICHIGAN...LOW LEVEL FLOW NOW TURNING INTO THE NW AND WILL PERSIST THROUGH THE DAY. WITH ARRIVAL OF UPSTREAM WAVE/ ASSOCIATED DEEPER MOISTURE/AND ERODING INVERSION HEIGHTS...EXPECT SNOW SHOWERS TO INCREASE ACROSS THE REGION DURING THE AFTERNOON (CATEGORICAL POPS IN NW LOWER AND ALONG THE PRESQUE ISLE SHORELINE. BUT AGAIN...WITH ONLY MODEST LAKE INSTABILITY WILL KEEP ACCUMULATIONS IN THE 1 TO 2 INCH RANGE IN THE FAVORED AREAS. TONIGHT THROUGH SUNDAY...GETS EVEN MORE INTERESTING AS SECONDARY STRONG MID LEVEL WAVE (KICKER) DROPS THROUGH THE SOUTHERN HALF OF THE STATE HELPING TO DRAG SFC TROUGH/COLD FRONT DOWN THROUGH NRN MICHIGAN OVERNIGHT...FOLLOWED BY SUBSTANTIALLY COLDER AIR (850 MB TEMPS DROPPING TO -16C TO -18C BY SUNDAY) OVERSPREADING THE STATE. ALTHOUGH STRONGEST FORCING WITH THE WAVE SLIDES ACROSS THE SRN PART OF THE STATE...CAN ENVISION AN AREA OF SNOWFALL SLIDING SOUTHWARD WITH THE TROUGH OVERNIGHT...WITH INTENSITIES ENHANCED BY THE LAKES AS IT PASSES THROUGH...AND PRODUCING A QUICK 1 TO 2 INCHES FOR MUCH OF THE AREA. LAKE ENHANCEMENT MAY ACTUALLY IMPACT BOTH THE LAKE MICHIGAN AND LAKE HURON SHORELINES...TACKING ON ADDITIONAL AMOUNTS. TRANSITION TO A NORTH FLOW LAKE EFFECT EVENT FOLLOWS LATE OVERNIGHT AND THROUGH SUNDAY MORNING BEFORE SOME DRYING COMMENCES IN THE AFTERNOON. LAKE EFFECT PARAMETERS LATE TONIGHT THROUGH SUNDAY MORNING LOOKING GOOD FOR MOD-HEAVY LAKE EFFECT SNOW POSSIBILITIES AS DELTA T/S INCREASE TO AROUND 20C COUPLED WITH WEAK OR NON EXISTANT INVERSION HEIGHTS AND PLENTY OF LOW LEVEL MOISTURE AROUND. RIGHT NOW...AREAS AROUND LEELANAU COUNTY AND GRAND TRAVERSE BAY SOUTH TO MANISTEE LOOKING MOST FAVORED ASSUMING MODELS HAVE A GOOD HANDLE ON THE FLOW REGIME BEHIND THE FRONT. AND COUPLED WITH THE OVERNIGHT SNOWFALL...ACCUMULATIONS APPROACHING WARNING CRITERIA A GOOD BET BY SUNDAY AFTERNOON IN THOSE AREAS. PROBABLY CLOSE ENOUGH TO WARRANT ISSUING A LAKE EFFECT SNOW WATCH FOR TONIGHT THROUGH SUNDAY ALTHOUGH LATER SHIFTS MAY OPT TO TRANSITION WATCH INTO ADVISORIES IF SHIFTING LOW LEVEL WINDS DO NOT COOPERATE. MONDAY THROUGH WEDNESDAY...NO CHANGE IN THE ONGOING PATTERN THROUGH MIDWEEK AND BEYOND. BLOCKING RIDGE PATTERN IN THE EASTERN PACIFIC ONLY STRENGTHENS FURTHER...WHILE DOWNSTREAM LONG WAVE TROUGHING ACROSS CENTRAL AND EASTERN NAOM DEEPENS. WITHIN THE LONG WAVE TROUGH PATTERN...SERIES OF SHORT WAVES EXPECTED TO SLIDE THROUGH THE REGION DURING THE UPCOMING WEEK EACH SERVING TO REINFORCE THE COLD AIR OVER THE GREAT LAKES. IN BETWEEN SYSTEMS WITH SFC HIGH PRESSURE NOSING INTO THE REGION...MAY GET A BIT OF A BREAK (AT LEAST FROM HEADLINES) ON MONDAY WITH JUST CHANCY POPS FOR THE SNOW BELTS. NEXT SHORT WAVE CURRENTLY FORECAST TO DROP THROUGH THE REGION ON TUESDAY BRINGING MORE WIDESPREAD SNOW. POSSIBLY ANOTHER BREAK FOR WEDNESDAY BEHIND THIS SYSTEM...BEFORE YET ANOTHER WAVE ARRIVES LATE WEDNESDAY. ADAM && .APX WATCHES/WARNINGS/ADVISORIES...LAKE EFFECT SNOW WATCH...TONIGHT THROUGH SUNDAY...MIZ020-025-026-031. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 615 AM EST SAT JAN 27 2007 .DISCUSSION... MAIN FCST CONCERN IS LAKE EFFECT EVENT TODAY THRU SUN. WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A SHORTWAVE TROF EXTENDING FROM JUST N OF LAKE SUPERIOR TO ND/MT. 00Z SOUNDINGS AT CYQD/CWPL SHOWED NEAR SATURATION TO AROUND 600MB IN THE VCNTY OF THIS TROF...AND IMPRESSIVE 12HR 500MB HEIGHT FALLS OF 200M/130M WERE NOTED AT KINL/CWPL RESPECTIVELY. ANOTHER SHORTWAVE WAS DIVING S THRU CNTRL MANITOBA. IT IS THIS FEATURE THAT WILL BRING A PERIOD OF LAKE ENHANCEMENT LATE THIS AFTN AND EVENING. AT THE SFC...LOW PRES TROF ASSOCIATED WITH FIRST SHORTWAVE EXTENDS FROM LAKE HURON ACROSS ERN LAKE SUPERIOR TO VCNTY OF LAKE NIPIGON. WITH MOST OF THE FCST AREA TO THE W OF SFC LOW PRES TROF...NW WINDS ARE THE RULE EARLY THIS MORNING. LAKE ENHANCMENT HAS TAKEN OFF IN A ZONE OF LOW-LEVEL CONVERGENCE FROM NRN ONTONAGON COUNTY/CNTRL HOUGHTON COUNTY INTO BARAGA COUNTY. REFLECTIVITIES HAVE BEEN ABOVE 30DBZ AT TIMES. HOWEVER...RECENT SFC OBS SHOW THE CONVERGENCE WEAKENING WHICH SHOULD RESULT IN SOME DIMINISHING OF THIS SNOW AREA. ALTHOUGH 850MB TEMP ON 00Z KINL SOUNDING WAS ONLY -10C...-15C/-18C WERE NOTED AT CWPL/CYQD. 00Z MODEL RUNS INDICATE THAT THE 00Z/26JAN NAM WAS ACTUALLY ON THE RIGHT TRACK YESTERDAY WITH ITS SLOWER MOVEMENT OF SFC TROF S ACROSS LAKE SUPERIOR TODAY. TIMING ON THE LATEST RUNS IS VERY SIMILAR...BUT THERE ARE SOME DIFFERENCES IN THE DETAILS OF WIND STRUCTURE AROUND SFC TROF/COLD FRONT. WILL LEAN STRONGLY TOWARD RUC13 AND IN PARTICULAR THE LOCAL HIGH RESOLUTION WRF-ARW AS THEY INDICATE A MUCH SHARPER WIND SHIFT WHICH IS TYPICALLY THE CASE WITH TROFS PASSING ACROSS LAKE SUPERIOR. LOCAL WRF-ARW TIMING BRINGS TROF TO THE KEWEENAW LATE MORNING AND TO THE REMAINING COUNTIES BORDERING LAKE SUPERIOR IN THE 18Z-21Z TIME FRAME. WOULD LIKE TO SEE A SOMEWHAT COLDER AIRMASS WITH LES ALREADY OCCURING ON THE LAKE FOR MORE CERTAINTY ON A BAND OF HVY SNOW TO ACCOMPANY WIND SHIFT. HOWEVER...MODELS DROP 850MB TEMPS TO -13C E AND -18C W ACROSS THE LAKE BY LATE MORNING WHICH IS CERTAINLY SUFFICIENT FOR LAKE ENHANCEMENT WITH INITIAL MIDLEVEL TROF PASSAGE. W END SHOULD SEE HEAVIEST SNOW WITH NOTABLY COLDER AIR ACCOMPANYING SFC TROF PASSAGE. WOULDN`T BE SURPRISED TO SEE A BRIEF PERIOD OF 1-3IN/HR SNOW RATES THERE AS WIND SHIFT PASSES. DEEP MOISTURE PROFILE NOTED ON CWPL/CYQD SOUNDINGS WILL THEN SET THE STAGE FOR QUICK DEVELOPMENT OF HEALTHY N-S ORIENTED LES BANDS IN THE WAKE OF SFC TROF/COLD FRONT. AS THAT SETS UP...ATTENTION IS ON MANITOBA SHORTWAVE. WITH SHORTWAVE ON ALMOST A DUE S TRACK...POCKET OF DECENT DEEP LAYER FORCING PER 850-500MB QVECTOR CONVERGENCE WILL IMPACT MAINLY WRN LAKE SUPERIOR FROM LATE AFTN UNTIL 06-09Z. THUS...EXPECT VERY HVY SNOW TO OCCUR OVER GOGEBIC/ONTONAGON COUNTIES LATE AFTN/EVENING UNDER FAVORABLE NRLY LOW-LEVEL FLOW. CONFIDENCE IS HIGH THAT THE AREA FROM IRONWOOD TO WAKEFIELD...BERGLAND AND THE PORCUPINE MOUNTAINS WILL EASILY SEE A FOOT OF SNOW BY DAYBREAK SUN. WOULD NOT BE SURPRISED TO SEE A FEW SPOTS IN THAT AREA REACH 18 INCHES. THE NCNTL FCST AREA WILL ONLY GET BRUSHED BY THE FORCING FROM SHORTWAVE...BUT DEEP MOISTURE UPWARDS OF 10KFT AND BRIEF LACK OF INVERSION MID/LATE EVENING STILL ARGUES FOR 10 OR MORE INCHES OVER THE HIGHER TERRAIN BY SUNRISE SUN. BASED ON SLIGHTLY E OF DUE N LOW-LEVEL WIND FLOW DURING PERIOD OF DEEP MOISTURE/ENHANCEMENT FROM SHORTWAVE...EXPECT GREATEST ACCUMULATIONS FROM THE HIGHER TERRAIN OF ERN BARAGA COUNTY TO ISHPEMING/NEGAUNEE AND SKANDIA. WILL NEED TO WATCH THE TIP OF THE KEWEENAW AS N WIND WILL FAVOR THE HIGHER TERRAIN FROM AROUND PHOENIX TOWARD COPPER HARBOR. ACCUMULATIONS SHOULD NEAR 10 INCHES THERE. EXPECT SOMEWHAT LIGHER TOTALS ACROSS THE REST OF THE KEWEENAW PENINSULA AS N WIND IS NOT AS FAVORABLE S OF PHOENIX. FOR THE ADVY AREA OF DELTA/NRN SCHOOLCRAFT...HAVE CONCERN ACCUMULATIONS MAY FALL A BIT SHORT OF CRITERIA SINCE 010-020 WIND DIRECTION DURING ENHANCEMENT PERIOD IS NOT IDEAL FOR THAT AREA. STILL...POTENTIAL IS SUFFICIENT TO LET ADVYS RIDE. BTWN 09-12Z...DEEP MOISTURE PULLS OUT QUICKLY AND INVERSION CRASHES DOWN TO 4-5KFT PER NAM/GFS FCST SOUNDINGS. SO MDT/HVY LES SHOULD RAPIDLY DIMINISH WITH MORE SEPARATION DEVELOPING BTWN BANDS. WINDS WILL ALSO BECOME MORE ANTICYLONIC AS THEY BACK THRU THE DAY SUN TO A NW DIRECTION. SO...ACCUMULATIONS SUN SHOULD BE LIGHT ON THE ORDER OF 1 TO 4 INCHES WITH THE GREATEST AMOUNTS OVER THE E DUE TO LONGER FETCH PARTIALLY COUNTERACTING THE INCOMING DRY ARCTIC AIRMASS. WOULD NOT BE SURPRISED TO SEE HEADLINES CANCELLED OR DOWNGRADED SUN BEFORE EXPIRATION TIMES ARE REACHED. LIGHT LES WILL PERSIST SUN NIGHT THRU TUE UNDER A MOSTLY NW LOW-LEVEL WIND FLOW REGIME WITH 850MB TEMPS HOVERING GENERALLY AROUND -20C. LOW INVERSION/DRY ARCTIC AIRMASS WILL LEAD TO ONLY LIGHT ACCUMULATIONS. THERE MAY BE SOME PERIODS WHERE WINDS WILL BE LIGHT ENOUGH PER NAM/GFS TO ALLOW FOR LOCALIZED CONVERGENCE ZONES TO DEVELOP. THIS WOULD GIVE LES A BOOST...BUT THE OVERALL DRY ENVIRONMENT WITH LOW INVERSIONS WILL STILL BE A SIGNIFICANT LIMITING FACTOR. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SUN MIZ002-009. LAKE EFFECT SNOW WARNING 1 PM TODAY TO 1 AM EST MON MIZ004>006. LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST SUN MIZ001-003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUN MIZ084. LAKE EFFECT SNOW ADVISORY 1 PM TODAY UNTIL 1 AM EST MON MIZ013-085. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 915 AM CST SAT JAN 27 2007 .DISCUSSION... DYNAMICALLY THERE IS A COUPLE OF INTERESTING FEATURES THAT ARE CONTROLLING THE SENSIBLE CONDITIONS ACROSS THE EASTERN PLAINS AND MISSOURI OZARKS REGION. A WELL DEVELOPED UPPER LOW IS CURRENTLY 1515Z TRACKING ACROSS OKLAHOMA. A BAND OF MODERATE PRECIPITATION FROM CENTRAL OKLAHOMA TO NORTHEAST OKLAHOMA...IS BEING DRIVEN BY BOTH PRESSURE ADVECTIVE PROCESSES AND RISING POTENTIAL TEMPERATURE SURFACES WITH RESPECT TO TIME. OVERLAYING THE RUC 295 POTENTIAL TEMPERATURE SURFACE ANALYSIS WITH RADAR SUGGESTS THAT THIS ENHANCED AREA OF FORCING IS BASICALLY AN ESTABLISHED TROWAL POSITIONED NORTH/NORTHEAST OF THE LOW CENTER. NORTHERN STREAM SHORTWAVE ENERGY SLAMMING DOWN FROM THE NORTHERN PLAINS WILL CAUSE THE OKLAHOMA LOW TO WEAKEN WITH TIME AS IT SHIFTS INTO A CONFLUENT PATTERN OVER THE ARKANSAS AND MISSOURI OZARKS. THEREFORE THIS BAND OF MODERATE PRECIP OVER OKLAHOMA SHOULD EXPERIENCE WEAKENING THIS MORNING AND AFTERNOON AS IT SHIFTS INTO ARKANSAS AND POSSIBLY SOUTHERN MISSOURI. WILL KEEP A CLOSE ON RADAR TRENDS...BUT FOR NOW SIGNIFICANT CHANGES TO WEATHER AND POP GRIDS ARE NOT ANTICIPATED. OTHERWISE SOME FLURRIES AND VERY LIGHT SNOW ARE OCCURRING OVER SEVERAL AREAS LATE THIS MORNING. THIS WILL NOT AMOUNT TO MUCH...AND WILL LIKELY TAPER OFF BY THIS EVENING. CRAMER && .AVIATION... VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD AT THE SPRINGFIELD AND JOPLIN TERMINALS. BROKEN TO OVERCAST CEILINGS WILL PERSIST WITH CLOUD DECKS AROUND 6-8 KFT. SOME VERY LIGHT PRECIPITATION MAY CREATE SOME MVFR CONDITIONS BUT THESE WILL AFFECT AREAS MAINLY TO THE SOUTH OF THE SPRINGFIELD AND JOPLIN TERMINALS. THE CLOUDINESS WILL DECREASE AFTER 00Z. GAEDE && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ WFO SGF mo AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BINGHAMTON NY 1059 AM EST SAT JAN 27 2007 .SHORT TERM /REST OF TODAY/... WM FNT DEFINITELY MAKING ITS PRESENCE FELT ACROSS WNY. SFC LOW SITS NR LK HURON WITH WEAKER LOW CENTERED NR KBUF. ASSOC FNT STRETCHED FROM APPROX KBUF-KDSV-KELM. TIGHT TEMP GRADIENT WITH 28F AT PENN-YAN TO 15F AT SYRACUSE. GREATEST PRESSURE FALLS CENTERED OFF THE JERSEY SHORE INDICATES THE SYSTEM WILL LIKELY MOVE SOUTH AND EAST...SOUTH OF SYRACUSE. THIS WOULD KEEP NRN ZONES IN COLD AIR ALL DAY AND HAVE CUT BACK ON TEMPS TO SHOW VERY LITTLE DIURNAL CHANGE. AM NOT EXTREMELY IMPRESSED WITH MUCH WARMUP TODAY AND HAVE TRIMMED BACK TEMPS NEARLY EVERYWHERE. AS FOR FZRA ADVISORY...STILL RECEIVING NUMEROUS REPORTS OF SLICK ROADS ASSOC WITH GLAZE. WILL KEEP ADVISORY UP THRU AT LEAST 18Z AND RE-EVALUATE AT THAT TIME. SNDGS INDICATE LITTLE CHANGE BEFORE THEN WITH CLD TOP TEMPS REMAINING WARM. ECHOES ON RADAR HAVE WEAKENED CONSIDERABLY IN THE PAST HOUR AND OBS HAVE GENERALLY CHANGED OVER TO ALL SNOW. EXPECT FZDZ TO BECOME LESS LIKELY BY AFTERNOON BUT WILL NOT MAKE ANY CHGS TO POPS AT THIS TIME. && .PREV DISCUSSION... /ISSUED 842 AM EST SAT JAN 27 2007/ SHORT TERM /REST OF TODAY/... HAVE HOISTED FREEZING RAIN ADVISORY FOR EASTERN SECTIONS OF THE AREA...MAINLY EAST OF A SYRACUSE TO CORTLAND TO WALTON LINE. HAVE RECEIVED SEVERAL REPORTS THIS MORNING OF SLICK ROADS IN THESE AREAS DUE TO LIGHT FZDZ/FZRA. PATCHY FZDZ EXPECTED ELSEWHERE BUT MEASURABLE PCPN LIKELY TO BE CONFINED TO I-81 CORRIDOR AND EAST. RADAR SHOWING WK RETURNS INDICATIVE OF VERY FINE PARTICLES. LIGHT SNOW MIXING IN AT TIMES BUT MAIN PROBLEM WILL BE GLAZING AND NOT RELATED TO SNOW ACCUMS. THUS...HAVE OPTED FOR FZRA ADVISORY UNTIL 1 PM. WILL CONTINUE TO MONITOR AND ADJUST ADVISORY AREA IF NEEDED. PREV DISCUSSION... /ISSUED 642 AM EST SAT JAN 27 2007/ AVIATION /12Z-12Z/... A WEAK SURFACE LOW CURRENTLY OVER SOUTHERN LAKE HURON WILL MOVE ACROSS THE AREA THIS AFTERNOON. WITH ONLY WEAK LIFT ASSOCIATED WITH THIS FEATURE PRECIP WILL BE LIMITED AND COULD EITHER BE SPOTTY FREEZING DRIZZLE OR LIGHT SNOW. IN GENERAL CONDITIONS THROUGH THE PERIOD WILL BE MVFR DUE TO CIGS. CIGS WILL LOWER BY MID MORNING WITH VSBY RESTRICTIONS TO MVFR AT KSYR THRU 18Z, DUE TO FREEZING DRIZZLE AND LIGHT SNOW. MVFR VSBY RESTRICTIONS DUE TO FOG ARE ALSO EXPECTED AT KITH/KBGM BTW 14Z-18Z. WINDS WILL REMAIN BTW 5-10 KNOTS, PRIMARILY SOUTHEAST EARLY THIS MORNING THEN SOUTHERLY BY MID MORNING SHIFTING TO SOUTHWEST EARLY THIS AFTERNOON TO WESTERLY TOWARD EVENING. LATE IN THE PERIOD RESTRICTIONS IN VSBY DUE TO SNOW SHOWERS ARE LIKELY AT KSYR/KITH/KBGM. RRM PREV DISCUSSION... /ISSUED 418 AM EST SAT JAN 27 2007/ SHORT TERM /TODAY THROUGH TUESDAY/... QUIET WEATHER WEEKEND WITH WARMER TEMPS AND LIGHT PRECIP. ATTM UNDER A WEAK UL RIDGE. WAA AHEAD OF A SFC LOW MOVG ESE FROM MICHIGAN. IN WEAK OVERRUNNING WITH SOME LIGHT LAKE ENHANCED RADAR ECHOES MOSTLY ALONG THE SOUTH SHORE OF LAKE ONTARIO. OBS IN SRN ONTARIO AND RUC SHOW SOME LIGHT FREEZING DRIZZLE. NO MEASURABLE. DENDRITE ZONE ABOVE SATURATED LOW LEVELS. MOISTURE AND DYNAMICS LACKING SO WILL NOT ISSUE ANYTHING ON THIS AND CONT THE CHC FZDZ IN GRIDS AND ZONES THIS MORNING. THIS LOW WILL CROSS THE CWA THIS AFTN LEAVING BEHIND A WEAK TROF FOR TONIGHT. SOME LIGHT SNOW NEAR THE LOW TRACK BUT SNOW ACCUMS WILL BE AN INCH OR LESS WITH TEMPS IN THE 30S. ALSO BEHIND THE LOW WEAK CAA STARTS. QPF AGAIN LIGHT TONIGHT. ON SUNDAY A SHORT WAVE DIVES SE INTO THE OHIO VALLEY THEN THE MID ATLANTIC. THIS WILL SET OFF SOME SNOW SHOWERS WITH DEEPER MOISTURE. AMOUNTS AGAIN LIGHT WITH BEST DYNAMICS S AND E. SUNDAY NIGHT FLOW GOES AGAIN TO NW WHILE 850 TEMPS GO TO -20C. LAKE INSTABILITY GOES EXTREME. FLOW STARTS OUT NW SO MULTIBANDS. ON MONDAY A SHORT WAVE MOVES THROUGH AND SHIFTS THE FLOW AROUND TO A MORE FAVORABLE 290 TO 300 FLOW SENDING IT INTO SYR. SNOW AMOUNTS COULD BE ENOUGH FOR A LES ADVISORY MONDAY INTO TUESDAY. TAC PREV DISCUSSION... /ISSUED 331 PM EST FRI JAN 26 2007/ LONG TERM /TUESDAY THROUGH FRIDAY/... COLD PATTERN WILL CONTINUE WITH CLOUDS AND SNOW SHOWERS OFF THE LAKES AND AN OCCASIONAL WEAK DISTURBANCE OR REINFORCING COLD WAVE MOVING THROUGH. ON TUESDAY...WEAK LOW PRES AREA WILL MOVE ACROSS THE LAKES AND NEW YORK BRINGING A CHANCE OF SNOW SHOWERS AND FLURRIES. HIGH PRES CENTER WILL PASS ACROSS PA ON WED WITH WLY WINDS OFF THE LAKES. ANOTHER LOW PRES AREA MOVES ACROSS THE LAKES INTO SE CANADA THU BRINGING ANOTHER COLD FRONT THROUGH NY AND PA THU NIGHT WITH SNOW SHOWERS POSSIBLE. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ009-018-036-037-044>046-057-062. PA...NONE. && $$ SHORT TERM...PB ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BINGHAMTON NY 842 AM EST SAT JAN 27 2007 .SHORT TERM /REST OF TODAY/... HAVE HOISTED FREEZING RAIN ADVISORY FOR EASTERN SECTIONS OF THE AREA...MAINLY EAST OF A SYRACUSE TO CORTLAND TO WALTON LINE. HAVE RECEIVED SEVERAL REPORTS THIS MORNING OF SLICK ROADS IN THESE AREAS DUE TO LIGHT FZDZ/FZRA. PATCHY FZDZ EXPECTED ELSEWHERE BUT MEASURABLE PCPN LIKELY TO BE CONFINED TO I-81 CORRIDOR AND EAST. RADAR SHOWING WK RETURNS INDICATIVE OF VERY FINE PARTICLES. LIGHT SNOW MIXING IN AT TIMES BUT MAIN PROBLEM WILL BE GLAZING AND NOT RELATED TO SNOW ACCUMS. THUS...HAVE OPTED FOR FZRA ADVISORY UNTIL 1 PM. WILL CONTINUE TO MONITOR AND ADJUST ADVISORY AREA IF NEEDED. && .PREV DISCUSSION... /ISSUED 642 AM EST SAT JAN 27 2007/ AVIATION /12Z-12Z/... A WEAK SURFACE LOW CURRENTLY OVER SOUTHERN LAKE HURON WILL MOVE ACROSS THE AREA THIS AFTERNOON. WITH ONLY WEAK LIFT ASSOCIATED WITH THIS FEATURE PRECIP WILL BE LIMITED AND COULD EITHER BE SPOTTY FREEZING DRIZZLE OR LIGHT SNOW. IN GENERAL CONDITIONS THROUGH THE PERIOD WILL BE MVFR DUE TO CIGS. CIGS WILL LOWER BY MID MORNING WITH VSBY RESTRICTIONS TO MVFR AT KSYR THRU 18Z, DUE TO FREEZING DRIZZLE AND LIGHT SNOW. MVFR VSBY RESTRICTIONS DUE TO FOG ARE ALSO EXPECTED AT KITH/KBGM BTW 14Z-18Z. WINDS WILL REMAIN BTW 5-10 KNOTS, PRIMARILY SOUTHEAST EARLY THIS MORNING THEN SOUTHERLY BY MID MORNING SHIFTING TO SOUTHWEST EARLY THIS AFTERNOON TO WESTERLY TOWARD EVENING. LATE IN THE PERIOD RESTRICTIONS IN VSBY DUE TO SNOW SHOWERS ARE LIKELY AT KSYR/KITH/KBGM. RRM PREV DISCUSSION... /ISSUED 418 AM EST SAT JAN 27 2007/ SHORT TERM /TODAY THROUGH TUESDAY/... QUIET WEATHER WEEKEND WITH WARMER TEMPS AND LIGHT PRECIP. ATTM UNDER A WEAK UL RIDGE. WAA AHEAD OF A SFC LOW MOVG ESE FROM MICHIGAN. IN WEAK OVERRUNNING WITH SOME LIGHT LAKE ENHANCED RADAR ECHOES MOSTLY ALONG THE SOUTH SHORE OF LAKE ONTARIO. OBS IN SRN ONTARIO AND RUC SHOW SOME LIGHT FREEZING DRIZZLE. NO MEASURABLE. DENDRITE ZONE ABOVE SATURATED LOW LEVELS. MOISTURE AND DYNAMICS LACKING SO WILL NOT ISSUE ANYTHING ON THIS AND CONT THE CHC FZDZ IN GRIDS AND ZONES THIS MORNING. THIS LOW WILL CROSS THE CWA THIS AFTN LEAVING BEHIND A WEAK TROF FOR TONIGHT. SOME LIGHT SNOW NEAR THE LOW TRACK BUT SNOW ACCUMS WILL BE AN INCH OR LESS WITH TEMPS IN THE 30S. ALSO BEHIND THE LOW WEAK CAA STARTS. QPF AGAIN LIGHT TONIGHT. ON SUNDAY A SHORT WAVE DIVES SE INTO THE OHIO VALLEY THEN THE MID ATLANTIC. THIS WILL SET OFF SOME SNOW SHOWERS WITH DEEPER MOISTURE. AMOUNTS AGAIN LIGHT WITH BEST DYNAMICS S AND E. SUNDAY NIGHT FLOW GOES AGAIN TO NW WHILE 850 TEMPS GO TO -20C. LAKE INSTABILITY GOES EXTREME. FLOW STARTS OUT NW SO MULTIBANDS. ON MONDAY A SHORT WAVE MOVES THROUGH AND SHIFTS THE FLOW AROUND TO A MORE FAVORABLE 290 TO 300 FLOW SENDING IT INTO SYR. SNOW AMOUNTS COULD BE ENOUGH FOR A LES ADVISORY MONDAY INTO TUESDAY. TAC PREV DISCUSSION... /ISSUED 331 PM EST FRI JAN 26 2007/ LONG TERM /TUESDAY THROUGH FRIDAY/... COLD PATTERN WILL CONTINUE WITH CLOUDS AND SNOW SHOWERS OFF THE LAKES AND AN OCCASIONAL WEAK DISTURBANCE OR REINFORCING COLD WAVE MOVING THROUGH. ON TUESDAY...WEAK LOW PRES AREA WILL MOVE ACROSS THE LAKES AND NEW YORK BRINGING A CHANCE OF SNOW SHOWERS AND FLURRIES. HIGH PRES CENTER WILL PASS ACROSS PA ON WED WITH WLY WINDS OFF THE LAKES. ANOTHER LOW PRES AREA MOVES ACROSS THE LAKES INTO SE CANADA THU BRINGING ANOTHER COLD FRONT THROUGH NY AND PA THU NIGHT WITH SNOW SHOWERS POSSIBLE. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...FREEZING RAIN ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ009-018-036-037-044>046-057-062. PA...NONE. && $$ SHORT TERM...PB ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RENO NV 909 AM PST SAT JAN 27 2007 .UPDATE... ADDED ISOLATED SHOWERS FOR THE SIERRA FROM TAHOE SOUTH AND MODIFIED THE SKY COVER FORECAST FOR TODAY. RUC SHOWS INCREASING INSTABILITY WITH A LOW LEVEL CONVERGENCE...UPPER LEVEL DIVERGENCE COUPLET ALONG THE SIERRA THIS AFTERNOON AS THE LOW AND A WAVE ROUNDING THE BASE OF THE LOW MOVES INLAND. MAY NEED TO INCREASE SNOW SHOWER CHANCES TONIGHT AS MOISTURE INCREASES AND TEMPERATURES ALOFT DECREASE. ANY SNOW ACCUMULATIONS WOULD BE LIGHT. BRONG && .PREV DISCUSSION...ISSUED 335 AM PST SAT JAN 27 2007 .SHORT TERM... ADDED SLIGHT CHANCE POPS TO SATURDAY NIGHT FOR THE SIERRA AND NUDGED DOWN HIGHS TOWARDS MOS THE NEXT FEW DAYS (REASONABLE CONSENSUS AMONG MOS GUIDANCE). OTHERWISE...FEW CHANGES TO THE GRIDS. A STABLE REX BLOCK PATTERN WILL KEEP AN UPPER LOW WEST OF MONTEREY BAY WOBBLING AROUND NEAR THE CENTRAL CALIFORNIA COAST THROUGH SUNDAY NIGHT BEFORE DRIFTING SOUTH MONDAY NIGHT AND TUESDAY. A DEFORMATION AXIS TO THE NORTHEAST OF THE UPPER LOW WEST OF MONTEREY BAY IS SLIDING INTO NEVADA THIS MORNING. AT THIS POINT... THE AXIS IS PRODUCING ONLY MID LEVEL CLOUDS OVER NORTHERN NEVADA. AS THE DEFORMATION BAND EDGES SOUTH TO AROUND HIGHWAY 50 THIS EVENING WITH THE UPPER LOW WOBBLING CLOSER TO THE COAST (WITH -25C AT 500 MB)...SOME SHOWERS WILL BE POSSIBLE IN THE SIERRA. THE GFS INDICATES LIFTED INDEXES OF AROUND 0.5C LATE THIS AFTERNOON...FOR A WEAKLY CONVECTIVE ELEMENT TO THE SHOWERS (THERE WERE A FEW TINY CUMULUS ON FRIDAY WITH -23C AT 500 MB). THE SIERRA SHOWER THREAT CONTINUES SUNDAY WITH THE LOW PARKED NEAR THE CENTRAL CALIFORNIA COAST. SUNDAY NIGHT AND MONDAY...THE UPPER LOW IS PROGGED TO RETROGRADE UNDER THE AMPLIFIED WESTERN RIDGE FOR STABILIZING CONDITIONS AND A VERY LOW CHANCE OF SHOWERS IN THE SIERRA. MONDAY NIGHT...THE GFS THINKS WRAP AROUND MOISTURE WILL AFFECT PERHAPS MONO AND MINERAL COUNTIES. AS THIS IS QUITE SKETCHY AT THIS POINT...I LEFT THE RUNNING GHOST POPS. SNYDER .LONG TERM...TUESDAY THROUGH FRIDAY... WEAK UPPER LOW OFF CENTRAL CA CST DRIFTS FURTHER S ON TUESDAY NUDGED BY UPSTREAM S/WV DROPPING S ACROSS IDAHO. MODELS INDICATE SUFFICIENT RH/QPF AND INSTABILITY IN NE QUAD OF UPPER LOW TO MENTION SLGT CHANCE OF SNOW SHOWERS OVER MONO COUNTY TUES AFTN. UPPER LOW TRACKS FURTHER S INTO SRN CA BY WED WITH DRIER NELY FLOW ACROSS WRN NV AND SIERRA. CONTINUED DRY AND A LITTLE WARMER THURSDAY AND FRIDAY AS HIGH PRESSURE ALOFT REMAINS ALONG W COAST. LITTLE CHANGE IN TEMPS WITH ARCTIC AIR FORECAST TO STAY E OF CONTINENTAL DIVIDE. STRONG SFC BASED INVERSIONS EXPECTED UNDER HIGH PRESSURE DURING PERIOD FOR COLD MORNINGS AND POOR MIXING IN AFTERNOON. TEMPS REMAINING NEAR SEASONAL NORMAL FOR LATE JANUARY. CYLKE && .AVIATION... VFR CONDITIONS WILL CONTINUE THROUGH SUNDAY EXCEPT FOR ISOLATED SNOW SHOWERS WITH HIGHER MTNS OBSCURED ALONG SIERRA SOUTH OF LAKE TAHOE IN THE AFTN. CYLKE && && .REV WATCHES/WARNINGS/ADVISORIES... NV...NONE. CA...NONE. && $$ HTTP://WEATHER.GOV/RENO ca AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE GAYLORD MI 417 PM EST SAT JAN 27 2007 .DISCUSSION...MID LEVEL SHORTWAVES...COMBINED WITH LAKE ENHANCED SURFACE TROUGH...CREATING A VERY CHALLENGING FORECAST FOR THE NEAR TERM. MID AFTERNOON SURFACE/SATELLITE/RUC/AND REGIONAL RADAR ANALYSIS SHOWS SHOWS FIRST OF TWO SHORTWAVES TO INFLUENCE NORTHERN MICHIGAN WEATHER RACING SOUTHEAST ACROSS NORTHERN LAKE MICHIGAN WITH THE SECOND DROPPING INTO NORTHERN MINNESOTA. AT THE SURFACE...ELONGATED SURFACE TROUGH EXTENDS NORTHWEST FROM LOW PRESSURE OVER SOUTHERN GEORGIAN BAY TO SOUTH CENTRAL LAKE SUPERIOR. LAKE INDUCED MESOLOW LOCATED OVER CHIPPEWA COUNTY MOVING SLOWLY SOUTHEAST ALONG SURFACE TROUGH IN RESPONSE TO FIRST SHORTWAVE. OVER WATER INSTABILITY ON THE INCREASE ACROSS THE NORTHERN LAKES AS CAA CONTINUES TO DROP 850MB TEMPERATURES...WITH 20Z RUC40 ANALYSIS SHOWING TEMPERATURES OF -13C OVER NORTHERN LAKE MICHIGAN AND EASTERN LAKE SUPERIOR. WEST NORTHWEST FLOW LAKE ENHANCED SNOW SHOWERS...SOME VERY INTENSE WITH SNOWFALL RATES AT AN INCH PER HOUR (EVEN HAD THUNDERSNOW REPORTED WITH THE 20Z HOUGHTON LAKE OBSERVATION) CONTINUE TO CUT ACROSS MUCH OF NORTHERN LOWER MICHIGAN. FARTHER NORTH...KMQT AND MONTREAL RIVER RADARS SHOWING INTENSE BANDS OVER CENTRAL AND EASTERN LAKE SUPERIOR BECOMING INCREASINGLY INFLUENCED BY MESOLOW CIRCULATION WITH NORTHWEST TO SOUTHEAST ORIENTED BANDS ON BACKSIDE OF CIRCULATION INTERSECTING THE LAKE SUPERIOR SHORELINE WILL WEST OF CHIPPEWA COUNTY. FORECAST CONCERN TONIGHT AND SUNDAY CENTERS ON AMOUNT AND LOCATION OF LAKE EFFECT SNOWS. TONIGHT...SHORTWAVE OVER NORTHERN LAKE MICHIGAN CLEARS THE FORECAST AREA BY EARLY THIS EVENING AS EASTERN UPPER MICHIGAN SURFACE TROUGH SAGS SOUTH...REACHING A POSITION FROM NEAR ALPENA TO THE TIP OF THE LEELANAU COUNTY BY 06Z. SIDING WITH THE SLOWER NAM-WRF AND LATEST RUC IN THIS REGARD WITH MUCH BETTER INITIALIZATION OF SURFACE FEATURES. FLOW OVER NORTHERN LOWER SLOWLY VEERS FROM WEST NORTHWEST EARLY THIS EVENING TO MORE NORTHWESTERLY BY MIDNIGHT. THERMODYNAMICALLY SPEAKING...LAKE EFFECT PARAMETERS OVER NORTHERN LAKE MICHIGAN REMAIN IMPRESSIVE THIS EVENING WITH NAM-WRF AND BUFKIT ANALYSIS SHOWING 850MB-700MB >80 PERCENT...DELTA T/S INCREASING TO 17C...LAKE INDUCED CAPE OF 370J/KG AND A LAKE INDUCED EQUILIBRIUM LEVEL OF 8.5KFT. GOOD CYCLONIC LOW LEVEL FLOW ALSO REMAINS OVER NORTHERN LOWER MICHIGAN THIS EVENING WITH ADDITIONAL ENHANCED CONVERGENCE AS TROUGH APPROACHES. HOWEVER...SOME KEY NEGATIVES TO MENTION. BANDS WILL BE SOMEWHAT TRANSITORY AS WINDS SLOWLY VEER AND LARGE SCALE SUBSIDENCE SETS IN BEHIND DEPARTING SHORTWAVE. THUS...NOT EXPECTING THINGS TO GET TOO OUT OF HAND THIS EVENING OVER NORTHWEST MICHIGAN WITH A GENERAL 2 TO 5 INCHES OF ACCUMULATION EXPECTED OVER FAVORED AREAS...WITH MOST OF THAT FALLING LATE THIS AFTERNOON THROUGH EARLY EVENING. HAVE GONE AHEAD AND ISSUED A LAKE SNOW ADVISORY TARGETING WHAT IS TYPICALLY KNOW AS THE BIG FIVE COUNTIES IN NORTHWEST MICHIGAN. OVER THE EASTERN UPPER...WINDS QUICKLY COME AROUND TO NORTH AND EVENTUALLY NORTHEAST...PUTTING THEM OUT OF PLAY FOR ANY SIGNIFICANT LAKE EFFECT. THINGS GET MORE INTERESTING LATER TONIGHT AS WINDS VEER TO NORTHERLY AND INSTABILITY INCREASES OVER NORTHERN LAKE MICHIGAN. AREA ALSO GETS CLIPPED BY NORTHERN FRINGES OF LARGE SCALE SYNOPTIC SUPPORT AS MINNESOTA SHORTWAVE DIVES INTO NORTHERN ILLINOIS. LAKE SNOW PARAMETERS REMAIN IMPRESSIVE WITH LAKE INDUCED CAPE AT NEARLY 500J/KG...EQUILIBRIUM LEVELS TO 10KFT...UNIDIRECTIONAL FLOW THROUGH THE CBL...AND OMEGA CENTERED IN THE PRIMARY DENDRITIC GROWTH ZONE FOR SEVERAL HOURS AFTER 06Z. PRIMARY CONCERN IS WINDS AS THEY LOOK TO SWING AROUND TO SLIGHTLY NORTHEAST LATE TONIGHT. IF THIS OCCURS..SNOW BANDS MAY REMAIN OFFSHORE. ALSO...BEST SYNOPTIC SUPPORT DOES PASS WELL SOUTH...REDUCING ENHANCEMENT POTENTIAL. STILL...COULD SEE A COUPLE HOURS OF INCH PER HOUR RATES OVER LEELANAU...BENZIE...GRAND TRAVERSE COUNTIES. OVER LAND TRAJECTORY SHOULD LIMIT RATES SOMEWHAT FOR MANISTEE COUNTY. NOT FORGETTING THE NORTHEAST LOWER...AS WINDS COME AROUND NORTHEAST COULD SEE A COUPLE INCHES ALONG THE LAKE HURON SHORELINE. SUNDAY...SYNOPTIC SUPPORT PASSES OFF TO THE EAST DURING THE MORNING WITH RAPID MID LEVEL DRYING OVERSPREADING NORTHERN MICHIGAN DURING THE AFTERNOON. HOWEVER...IMPRESSIVE NORTH FLOW LAKE EFFECT LOOKS TO CONTINUE FOR SEVERAL HOURS UNTIL THIS OCCURS WITH LAKE INDUCED CAPE INCREASING TO 550J/KG AND EQUILIBRIUM LEVELS INCREASING TO 11KFT. EXPECT SEVERAL MORE INCHES OVER AFOREMENTIONED AREAS CENTERED NEAR AND WEST OF GRAND TRAVERSE BAY. THUS...FEEL WARNINGS ARE WARRANTED FOR BENZIE...LEELANAU...AND GRAND TRAVERSE COUNTIES WITH 24 HOUR AMOUNTS EXPECTED TO APPROACH LOW END WARNING CRITERIA WITH ADVISORY CRITERIA BEING MET IN MANISTEE COUNTY. LATER IN THE DAY...WINDS BACK AROUND NORTHWEST AND FLOW GOES ANTICYCLONIC AS SURFACE RIDGE BEGINS TO BUILD IN. SNOW SHOWERS WILL ONCE AGAIN BEGIN TO SPREAD FARTHER INLAND...ALBEIT SIGNIFICANTLY WEAKER. MSB LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)...COLD WEATHER WILL PREVAIL THROUGH THE ENTIRE PERIOD...AS BLOCKING WEST RIDGE PATTERN UP THE WESTERN NORTH AMERICA COAST WILL KEEP LONGWAVE TROUGHING ACROSS THE EASTERN TWO-THIRDS OF THE COUNTRY. THIS WILL RESULT IN A SERIES OF SHORTWAVE TROUGHS THAT WILL MOVE THROUGH THE GREAT LAKES REGION...AND PERIODS/BOUTS OF LAKE EFFECT AND LAKE ENHANCED SNOW SHOWERS. TIMING OF THESE DIFFERENT SNOW EVENTS WILL BE DEFINED WITH MORE PRECISION AS EACH EVENT NEARS. THIS TYPE OF PATTERN COULD LEAD TO BETTER/GROWING SNOWPACK FOR NRN MICHIGAN. SUNDAY NIGHT...MAIN SHORTWAVE TROUGH AND SFC LOW WILL BE SE OF THE REGION SUNDAY NIGHT...WHICH WILL HAVE DRUG SFC TROUGHING THROUGH THE AREA.. LEFT BEHIND WILL BE A DRIER NW 1000-850MB WIND REGIME...WHICH WILL CONTINUE TO BACK WEST AS SFC HIGH PRESSURE AND MORE ANTI- CYCLONIC FLOW MOVES IN. LAKE INDUCED TROUGHING IS SUGGESTED BY BOTH GFS/NAM TO REDEVELOP FROM EASTERN LAKE SUPERIOR TO NRN LAKE HURON FOR THE OVERNIGHT HOURS. THIS SEEMS REASONABLE SEEING THAT THE LAND/WATER TEMPERATURE CONTRAST WILL BE INCREASING...AS H8 TEMPS DROP TO -20C. NOT A WHOLE LOT OF SNOW EXPECTED. UNDER THIS SYNOPTIC PATTERN EVOLUTION...SNOWFLAKES WILL BE GETTING PROGRESSIVELY SMALLER WITH COOLING TEMPS ALOFT...PLUS THE LOW LEVEL MOISTURE PROFILES ARE UNIMPRESSIVE...AND WE WILL BE LOSING THE ADDITIONAL CRYSTAL GROWTH IN THE LOWER LEVELS DUE TO THE COLDER TEMPERATURES. THIS EXPECTED EVEN THOUGH INVERSION HEIGHTS WILL BE DECENT FOR A PORTION OF THE EVENING AT 5500 FEET. MAY BE A BIT TRICKY ACROSS CHIPPEWA IF THE LAKE INDUCED TROUGHING ENHANCES LOW LEVEL CONVERGENCE OVER ANY ONE AREA...BUT THESE DETAILS ARE BEST DISCERNED CLOSER TO THE EVENT. WILL GO WITH A 1-1.5 INCH FORECAST. WINDS WILL BE SHIFTING MORE SO IN NRN LOWER AND WIND SPEEDS WILL BE DECREASING FROM 10-15 KNOTS TO AROUND 10KTS LATE. BEST SNOWS COULD BE FROM THE IMMEDIATE HIGHER TERRAIN TO ALONG THE COASTS. MONDAY AND MONDAY NIGHT...NEXT CLIPPER ARRIVES FROM THE NC PLAINS...BUT TRAVERSES TO OUR SW ACROSS NRN IL...SPREADING BEST ISENTROPIC/WAA SNOWS ACROSS SW LOWER MICHIGAN. REALLY TOUGH TO SAY HOW MUCH SYNOPTIC SNOWS WILL AFFECT OUR SRN MOST AREAS...BUT AT LEAST SOME LIGHT SNOWS SHOULD SPREAD INTO AREAS SOUTH OF GRAND TRAVERSE BAY. ALL OTHER AREAS SHOW A PROMINENT DRY LAYER BETWEEN 650-850MB. ALSO...LIGHT LAKE EFFECT SNOWS WILL LIKELY BE ONGOING IN NW FLOW REGIMES...BUT WINDS WILL BE LIGHT (AROUND 10KTS OR EVEN LESS)...SO INLAND PENETRATION MAY BE MINIMAL. ALL-IN-ALL...WILL KEEP 40% CHANCE OF SNOW SHOWERS WILL REMAIN THE BEST WAY TO GO...UNTIL THIS SYSTEMS DETAILS CAN COME TOGETHER. BEST CHANCES AREA SOUTH OF M-72 AND WEST OF I-75. WILL TENTATIVELY PUT IN AROUND AN INCH FOR MONDAY. LOTS OF UNCERTAINTY REVOLVES AROUND THE 1000-850MB WIND DIRECTION FOR MONDAY AFTERNOON AND NIGHT...WHERE PREVIOUS THOUGHTS WERE FOR A SHIFT TO WSW/SW. THIS NOT SO THE CASE WITH LATEST DEVELOPMENTS...BUT FEEL AS THOSE THESE DETAILS ARE LIKE MOST OTHERS AT THIS TIME PERIOD OUT...BEST LEFT FOR WHEN THE EVENT COMES CLOSER TO CURRENT TIME. WILL KEEP 40% CHANCES IN SAME AREAS ALL OF MONDAY NIGHT. TUESDAY...A GENERAL WNW/WEST FLOW TO BE AROUND AS SHORTWAVE TROUGH AXIS AND PERIOD OF SYNOPTIC SNOW LOOKS TO ROLL THROUGH THE REGION. THIS FEATURE DOES NOT LOOK ALL THAT IMPRESSIVE...WITH THE TEMP PROFILES DO SUGGEST THAT SLIGHT WARMING AND H8 TEMPS RISING INTO THE -16C RANGE MAY POSSIBLY LEAD TO BETTER FLAKES. NO WAY TO DETERMINE THESE SORT OF DETAILS...AND CHANCE OF SNOW SHOWER WILL SUFFICE. THE WINDS WILL AGAIN BE HARD TO DETERMINE...BUT AT LEAST SOME BACKING SHOULD LEAD TO BETTER SNOWS FOR AREAS WEST OF I-75 AND SOUTH OF M-68. TUESDAY NIGHT THROUGH FRIDAY...AS RIDGING BUILDS ACROSS THE WESTERN NORTH AMERICAN COAST...BETTER AND BETTER POSSIBILITIES RESIDE WITH SEEING COLDER TEMPERATURES...ALTHOUGH THE COLDEST AIR WILL BE ENTRENCHED ACROSS THE NC PLAINS. A SERIES OF SHORTWAVES (SAME PATTERN) WILL IMPACT THE AREA...POSSIBLY RESULTING IN MORE SW FLOW EVENTS AS UPPER LEVEL WINDS GO FROM NW TO SW BY LATE IN THE WORK WEEK. THIS WOULD IMPACT THE LAKE MICHIGAN SHORELINE...AS WELL AS FAR NRN LAKE HURON. MODELS SEEM RATHER AGREEABLE ON THIS EVOLUTION ATTM. RIGHT NOW...TIMING IS FOR A COLD FRONT TO ARRIVE TUESDAY...AND AGAIN FRIDAY NIGHT WITH ASSOCIATED SYNOPTIC SUPPORT FOR LAKE ENHANCED SNOW. TEMPS ARE COLD ENOUGH...TO WHERE SUFFICIENT WIND SPEEDS IN THE 10-15MPH RANGE WOULD RESULT IN LAKE EFFECT SNOWS TO CONTINUE IN PORTIONS OF THE SW TO NW FLOW REGIMES OF NRN MICHIGAN THROUGH THIS ENTIRE TIME. SMD && .APX WATCHES/WARNINGS/ADVISORIES...LAKE EFFECT SNOW WARNING...TONIGHT THROUGH SUNDAY...MIZ020-025-026. LAKE EFFECT SNOW ADVISORY...TONIGHT THROUGH SUNDAY...MIZ031. LAKE EFFECT SNOW ADVISORY...THROUGH TONIGHT...MIZ019>021-022>027-028. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 355 PM EST SAT JAN 27 2007 .SYNOPSIS... LATEST WATER VAPOR IMGRY ALONG WITH 400MB RUC HEIGHT ANALYSIS SHOWS A LOW PRESSURE TROUGH EXTENDING FROM JAMES BAY ACROSS THE UPPER GREAT LAKES AND INTO THE CENTRAL PLAINS. AT THE SFC THIS FEATURE IS REFLECTED AS A LOW PRESSURE TROUGH SITUATED OVER THE GREAT LAKES. ELSEWHERE ACROSS THE CONUS...UPPER LEVEL RIDGING IS NOTED IN THE NW UNITED STATES...FURTHER SOUTH...AN UPPER LEVEL LOW SITS JUST OFF THE COAST OF CALIFORNIA AND ZONAL FLOW DOMINATES THE EASTERN CONUS. BEHIND THE GREAT LAKES TROUGH...TEMPERATURES ARE COLD. AFTN TEMPERATURES ACROSS THE NORTHERN PLAINS ARE HOVERING JUST ABOVE ZERO WITH BELOW ZERO READINGS AT A FEW SPOTS...-3 AT GFK...6 AT 8D3...0 AT FAR. THESE TEMPS ALONG WITH MODEST NWRLY SFC WINDS HAS YIELDED WIND CHILL ADVISORIES FOR MUCH OF THIS AREA. CLOSER TO HOME TEMPS ARE MUCH WARMER WITH READINGS GETTING TO NEAR NORMAL TODAY OR SLIGHTLY ABOVE...25 AT ERY...19 AT NWS MQT...21 AT P59 AND 27 AT ISQ. LATEST RADAR TRENDS/SURFACE OBS SHOW LAKE EFFECT GOING STRONG ACROSS THE LAKE SUPERIOR/LAKE MICHIGAN NORTHERLY WIND SNOW BELTS. 12Z NAM BUFKIT SHOWS INVERSION HEIGHTS ON THE RISE...7000FT AT MQT...8000FT AT CMX THIS ALONG WITH 850MB TEMPS ARE AROUND -16 TO -20 GOOD LAKE EFFECT CONDITIONS. RADAR TRENDS SHOW THAT SNOW BANDS HAVE BEEN MAINLY MULTI-PARALLEL OFF OF THE WESTERN LAKE WITH SOUTHWARD PROPIGATING DOMINATE BANDING OCCURRING ACROSS THE EASTERN LAKE. CYCLONIC FLOW OVER THE EASTERN LAKE ASSOCIATED WITH THE DEPARTING TROUGH HAVE ALLOWED DOMINATE LES BANDS TO PROPAGATE SOUTHWESTLY AT ABOUT 10 KNOTS. .SHORT TERM (TONIGHT AND SUNDAY)... THE MAIN FORECAST CONCERN FOR THIS TIME PERIOD CONTINUES TO BE THE LAKE EFFECT SNOW THROUGH SUNDAY. WILL NOT ADJUST THE END TIMES OF THE WARNINGS OR ADVISORIES AT THIS TIME...SIDING TO WAIT UNTIL LATER THIS EVENING OR TOMORROW TO MAKE THIS DECISION. THERE SEEMS TO CONTINUE TO BE EVIDENCE TO DO SO...AS WINDS BECOME MORE WESTERLY (310 TO 270) AFTER 18Z SUNDAY ACROSS THE WESTERN THIRD OF LAKE SUPERIOR. INVERSION HEIGHTS SHOULD ALSO BEGINS TO SLOWLY CRASH TO 5KFT BY 12Z SUNDAY...AND THEN CLOSER TO 2.5KFT BY 21Z...PUTTING AN END TO HEAVY SNOW. THE CENTRAL AND EASTERN GROUP OF WARNINGS AND ADVISORIES STILL MAY WORK TIME WISE...AS THE FOCUS JUST CONTINUES TO SHIFT SLOWLY EASTWARD...WITH SLIGHTLY MORE MOISTURE TO WORK WITH AND A LONGER FETCH ACROSS LAKE SUPERIOR. THIS WOULD CUT OFF BARAGA COUNTY FROM RECEIVING MUCH MORE SNOW...BUT ALGER AND NORTHERN SCHOOLCRAFT SHOULD STILL BE RECEIVING SOME ADDITIONAL SNOW ACCUMULATIONS THROUGH SUNDAY AFTERNOON. WILL ALSO NEED TO KEEP AN EYE ON HOW STRONG AND HOW FAST THE QUICK MOVING SURFACE HIGH PRESSURE SYSTEM...SLIDES SOUTH-SOUTHEASTWARD FROM NORTH DAKOTA LATE TODAY AND INTO THE SOUTHERN PLAINS SUNDAY AFTERNOON...DRYING OUT OUR AIRMASS. OVERALL...WINDS HAVE BEEN SLOWER TO BECOME NORTHERLY THIS AFTERNOON...BUT ARE NOW STARTING TO COME AROUND...LEADING TO CONVERGENT SNOW BANDS ACROSS EASTERN MARQUETTE INTO ALGER COUNTY LATE THIS AFTERNOON. IN GENERAL...STUCK FAIRLY CLOSE TO THE RUC13 FOR WINDS...WHICH WAS FAIRLY CLOSE TO THE LOCAL WRF AND NAM. FOR COMPARISON THE GFS WAS TOO QUICK TO BRING DOWN THE NORTHERLY WINDS...SO HAVE RELIED HEAVILY ON NON-GFS MODELS FOR THIS FORECAST ISSUANCE FOR TONIGHT AND SUNDAY. HESITATE TO RAISE FORECAST TEMPS MUCH OVERNIGHT...EVEN WITH OUR CURRENT FORECAST BRING A COUPLE OF DEGREES BELOW GUIDANCE VALUES. GIVEN PLENTY OF COLD AIR UPSTREAM...WITH SINGLE DIGIT READINGS BELOW AND ABOVE ZERO ACROSS MUCH OF NORTHERN MINNESOTA...WE SHOULD BE ABLE TO MAKE IT INTO THE SINGLE DIGITS ABOVE ZERO. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... .SUNDAY NIGHT...LES SHOULD BE GREATLY DIMINISHED AS RDGG/SUBSIDENCE BUILDS IN FROM THE W AND FLOW BECOMES INCREASING ANTICYCLONIC. DEVELOPING LAND BREEZES COULD HELP LOW-LVL CONVERGENCE AND FOCUS SOME BETTER LES BANDS OVER ALGER-LUCE-NRN SCHOOLCRAFT COUNTIES WHERE I HAVE MAINTAINED LIKELY POPS. ELSEWHERE ALONG LAKE SUPERIOR RDGG AND DRY AIR SHOULD DIMINISH LES TO LIGHT SNOW SHOWERS OR FLURRIES. CLEARING OVER THE WESTERN INTERIOR WILL ALLOW TEMPS TO PLUMMET TO AROUND -10F OVER SOME FAVORED COLD DRAINAGE LOCATIONS. MONDAY AND MONDAY NIGHT...MODELS HAVE ANOTHER WEAK SHORTWAVE MOVING THROUGH BY AFTERNOON WHICH WILL SHIFT WEAK WIND FLOW BACK TO N AND BRING SOME LIGHT LES ONSHORE AGAIN SO KEPT CHC POPS OF 30/40 ALONG LAKE SUPERIOR ZONES. TUE INTO WED...MODELS INDICATE FLOW WILL BACK MORE WNW IN ADVANCE OF NEXT CLIPPER SYSTEM AS 850 MB TEMPS REMAIN IN -16 TO -18C RANGE OVER LAKE SUPERIOR. THIS WNW FLOW WILL TEND TO SHIFT LES BANDS BACK ALONG THE LAKE SUPERIOR SHORELINE SO HAVE CONFINED CHC POPS FOR SNOW OVER THESE LOCATIONS WITH SLIGHT CHC POPS OR DRY CONDITIONS FARTHER INLAND. FOLLOWED MORE CONSISTENT ECMWF WHICH SHOWS NEXT SIGNIFICANT CLIPPER SYSTEM TO MOVE IN ON THU SO INCLUDED CHC POPS FOR ENTIRE CWA AT THIS TIME. ECMWF INDICATES VERY COLD ARCTIC AIR (850 MB TEMPS OF AROUND -25C) WILL FOLLOW IN THE WAKE OF THIS CLIPPER SYSTEM. FORECAST BECOMES A BIT MORE UNCERTAIN BY NEXT FRI INTO SAT AS MODELS VARY ON TIMING OF CLIPPERS. THE GFS SHOWS ONE CLIPPER SYSTEM MOVING THROUGH ON FRI WITH ANOTHER TO FOLLOW ON SAT BRINGING REINFORCING SHOTS OF BITTER COLD ARCTIC AIR. THE 12Z ECMWF SHOWS A POLAR VORTEX DESCENDING FM HUDSON BAY WITH ANOTHER CLIPPER MOVING THROUGH THE AREA ON SAT WITH -30C AIR IN ITS WAKE. ECMWF SOLN SEEMS TO AGREE BETTER WITH GFS ENSEMBLE MEAN SO WOULD TEND TO FAVOR ECMWF SOLN MORE THAN OPERATIONAL GFS AT THIS POINT. ANYWAY...DESPITE TIMING DIFFERENCES...MODELS ARE IN AGREEMENT THAT NEXT WEEKEND WILL LIKELY BE BITTERLY COLD. && .MQT WATCHES/WARNINGS/ADVISORIES... LAKE EFFECT SNOW WARNING UNTIL 7 PM EST SUN MIZ002-009. LAKE EFFECT SNOW WARNING 1 PM TODAY TO 1 AM EST MON MIZ004>006. LAKE EFFECT SNOW ADVISORY UNTIL 10 PM EST SUN MIZ001-003. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST SUN MIZ084. LAKE EFFECT SNOW ADVISORY 1 PM TODAY UNTIL 1 AM EST MON MIZ013-085. HEAVY FREEZING SPRAY WARNING LAKE SUPERIOR. && $$ .SYNOPSIS...DJP .SHORT TERM...KF .LONG TERM...JV mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 221 PM EST SAT JAN 27 2007 .LONG TERM /SUNDAY THROUGH SATURDAY/... LONG RANGE PATTERN WILL BE CONTROLLED BY THE DEVELOPMENT OF A STRONG HUDSON BAY VORTEX AT 500 MB NEXT WEEK. TUESDAY THROUGH THURSDAY WILL BE UNSEASONABLY COLD WITH PRECIPITATION CHANCES MAINLY DUE TO LAKE EFFECT SNOW AND POSSIBLY ONE OR TWO WEAK CLIPPERS. BASED ON THIS WENT WITH HIGH CHANCE POPS CLOSEST TO LAKE ONTARIO... AND LOWER POPS FARTHER SOUTH ACROSS NORTHEAST PA. KEY TO THE FORECAST FOR LATE NEXT WEEK WILL BE WHETHER ENERGY DROPPING SOUTH ACROSS WESTERN CANADA CAN TURN THE UPPER FLOW INTO THE SOUTHWEST OVER THE EASTERN U.S... WHICH WOULD ALLOW FOR ONE OF THE CLIPPERS TO BRING SOME GULF MOISTURE NORTHWARD. THE ECMWF HAS BEEN ADVERTISING THIS SCENARIO FOR AWHILE NOW... WHILE THE GFS HAS GONE BACK AND FORTH. THIS SCENARIO WOULD ALLOW FOR A BRIEF PERIOD OF WARMER WEATHER LATE NEXT WEEK... ALONG WITH THE POSSIBILITY FOR A SIGNIFICANT SNOWFALL. ALL MODELS INDICATE THAT ANY MODERATION WOULD BE FOLLOWED BY A RAPID COOL-DOWN AGAIN NEXT WEEKEND. && .AVIATION /19Z-18Z/... EXPECT OVC MVFR TO VFR CIGS AND P6SM VSBYS INTO THIS EVENING. AREAS OF LIGHT SNOW WILL DEVELOP ACROSS CENTRAL NY THIS EVENING AND CONTINUE OVERNIGHT LOWERING VSBYS AND CIGS TO MVFR. && .PREV DISCUSSION... /ISSUED 1059 AM EST SAT JAN 27 2007/ SHORT TERM /REST OF TODAY/... WM FNT DEFINITELY MAKING ITS PRESENCE FELT ACROSS WNY. SFC LOW SITS NR LK HURON WITH WEAKER LOW CENTERED NR KBUF. ASSOC FNT STRETCHED FROM APPROX KBUF-KDSV-KELM. TIGHT TEMP GRADIENT WITH 28F AT PENN-YAN TO 15F AT SYRACUSE. GREATEST PRESSURE FALLS CENTERED OFF THE JERSEY SHORE INDICATES THE SYSTEM WILL LIKELY MOVE SOUTH AND EAST...SOUTH OF SYRACUSE. THIS WOULD KEEP NRN ZONES IN COLD AIR ALL DAY AND HAVE CUT BACK ON TEMPS TO SHOW VERY LITTLE DIURNAL CHANGE. AM NOT EXTREMELY IMPRESSED WITH MUCH WARMUP TODAY AND HAVE TRIMMED BACK TEMPS NEARLY EVERYWHERE. AS FOR FZRA ADVISORY...STILL RECEIVING NUMEROUS REPORTS OF SLICK ROADS ASSOC WITH GLAZE. WILL KEEP ADVISORY UP THRU AT LEAST 18Z AND RE-EVALUATE AT THAT TIME. SNDGS INDICATE LITTLE CHANGE BEFORE THEN WITH CLD TOP TEMPS REMAINING WARM. ECHOES ON RADAR HAVE WEAKENED CONSIDERABLY IN THE PAST HOUR AND OBS HAVE GENERALLY CHANGED OVER TO ALL SNOW. EXPECT FZDZ TO BECOME LESS LIKELY BY AFTERNOON BUT WILL NOT MAKE ANY CHGS TO POPS AT THIS TIME. PREV DISCUSSION... /ISSUED 842 AM EST SAT JAN 27 2007/ SHORT TERM /REST OF TODAY/... HAVE HOISTED FREEZING RAIN ADVISORY FOR EASTERN SECTIONS OF THE AREA...MAINLY EAST OF A SYRACUSE TO CORTLAND TO WALTON LINE. HAVE RECEIVED SEVERAL REPORTS THIS MORNING OF SLICK ROADS IN THESE AREAS DUE TO LIGHT FZDZ/FZRA. PATCHY FZDZ EXPECTED ELSEWHERE BUT MEASURABLE PCPN LIKELY TO BE CONFINED TO I-81 CORRIDOR AND EAST. RADAR SHOWING WK RETURNS INDICATIVE OF VERY FINE PARTICLES. LIGHT SNOW MIXING IN AT TIMES BUT MAIN PROBLEM WILL BE GLAZING AND NOT RELATED TO SNOW ACCUMS. THUS...HAVE OPTED FOR FZRA ADVISORY UNTIL 1 PM. WILL CONTINUE TO MONITOR AND ADJUST ADVISORY AREA IF NEEDED. PREV DISCUSSION... /ISSUED 642 AM EST SAT JAN 27 2007/ AVIATION /12Z-12Z/... A WEAK SURFACE LOW CURRENTLY OVER SOUTHERN LAKE HURON WILL MOVE ACROSS THE AREA THIS AFTERNOON. WITH ONLY WEAK LIFT ASSOCIATED WITH THIS FEATURE PRECIP WILL BE LIMITED AND COULD EITHER BE SPOTTY FREEZING DRIZZLE OR LIGHT SNOW. IN GENERAL CONDITIONS THROUGH THE PERIOD WILL BE MVFR DUE TO CIGS. CIGS WILL LOWER BY MID MORNING WITH VSBY RESTRICTIONS TO MVFR AT KSYR THRU 18Z, DUE TO FREEZING DRIZZLE AND LIGHT SNOW. MVFR VSBY RESTRICTIONS DUE TO FOG ARE ALSO EXPECTED AT KITH/KBGM BTW 14Z-18Z. WINDS WILL REMAIN BTW 5-10 KNOTS, PRIMARILY SOUTHEAST EARLY THIS MORNING THEN SOUTHERLY BY MID MORNING SHIFTING TO SOUTHWEST EARLY THIS AFTERNOON TO WESTERLY TOWARD EVENING. LATE IN THE PERIOD RESTRICTIONS IN VSBY DUE TO SNOW SHOWERS ARE LIKELY AT KSYR/KITH/KBGM. RRM PREV DISCUSSION... /ISSUED 418 AM EST SAT JAN 27 2007/ SHORT TERM /TODAY THROUGH TUESDAY/... QUIET WEATHER WEEKEND WITH WARMER TEMPS AND LIGHT PRECIP. ATTM UNDER A WEAK UL RIDGE. WAA AHEAD OF A SFC LOW MOVG ESE FROM MICHIGAN. IN WEAK OVERRUNNING WITH SOME LIGHT LAKE ENHANCED RADAR ECHOES MOSTLY ALONG THE SOUTH SHORE OF LAKE ONTARIO. OBS IN SRN ONTARIO AND RUC SHOW SOME LIGHT FREEZING DRIZZLE. NO MEASURABLE. DENDRITE ZONE ABOVE SATURATED LOW LEVELS. MOISTURE AND DYNAMICS LACKING SO WILL NOT ISSUE ANYTHING ON THIS AND CONT THE CHC FZDZ IN GRIDS AND ZONES THIS MORNING. THIS LOW WILL CROSS THE CWA THIS AFTN LEAVING BEHIND A WEAK TROF FOR TONIGHT. SOME LIGHT SNOW NEAR THE LOW TRACK BUT SNOW ACCUMS WILL BE AN INCH OR LESS WITH TEMPS IN THE 30S. ALSO BEHIND THE LOW WEAK CAA STARTS. QPF AGAIN LIGHT TONIGHT. ON SUNDAY A SHORT WAVE DIVES SE INTO THE OHIO VALLEY THEN THE MID ATLANTIC. THIS WILL SET OFF SOME SNOW SHOWERS WITH DEEPER MOISTURE. AMOUNTS AGAIN LIGHT WITH BEST DYNAMICS S AND E. SUNDAY NIGHT FLOW GOES AGAIN TO NW WHILE 850 TEMPS GO TO -20C. LAKE INSTABILITY GOES EXTREME. FLOW STARTS OUT NW SO MULTIBANDS. ON MONDAY A SHORT WAVE MOVES THROUGH AND SHIFTS THE FLOW AROUND TO A MORE FAVORABLE 290 TO 300 FLOW SENDING IT INTO SYR. SNOW AMOUNTS COULD BE ENOUGH FOR A LES ADVISORY MONDAY INTO TUESDAY. TAC PREV DISCUSSION... /ISSUED 331 PM EST FRI JAN 26 2007/ LONG TERM /TUESDAY THROUGH FRIDAY/... COLD PATTERN WILL CONTINUE WITH CLOUDS AND SNOW SHOWERS OFF THE LAKES AND AN OCCASIONAL WEAK DISTURBANCE OR REINFORCING COLD WAVE MOVING THROUGH. ON TUESDAY...WEAK LOW PRES AREA WILL MOVE ACROSS THE LAKES AND NEW YORK BRINGING A CHANCE OF SNOW SHOWERS AND FLURRIES. HIGH PRES CENTER WILL PASS ACROSS PA ON WED WITH WLY WINDS OFF THE LAKES. ANOTHER LOW PRES AREA MOVES ACROSS THE LAKES INTO SE CANADA THU BRINGING ANOTHER COLD FRONT THROUGH NY AND PA THU NIGHT WITH SNOW SHOWERS POSSIBLE. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. && $$ LONG TERM...MSE AVIATION...MSE ny AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1203 PM CST SAT JAN 27 2007 .UPDATE...AVIATION DISC ADDED TO UPDATE FOR 18Z TAFS. SEE BELOW. HAVE MADE SOME CONSIDERABLE REVISIONS TO THE FORECAST PACKAGE WITH ADVISORY CRITERIA WINDS AGAIN BUFFETING THE FORECAST AREA TODAY. THE DIFFERENCE BETWEEN YESTERDAY AND TODAY IS THE ADDITIONAL LIGHT SNOWFALL AND BLOWING SNOW COMBINED WITH MUCH COLDER AIR IN PLACE TODAY THAN YESTERDAY...WHICH IS YIELDING WIND CHILLS RIGHT AT OR JUST ABOVE WIND CHILL ADVISORY CRITERIA. REPORTS FROM AROUND THE AREA INDICATE THAT BLOWING SNOW OVER ROADS IS MAKING AN IMPACT ON TRAVEL...SO HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE REST OF TODAY /VALID TAIL 4 PM CST/ FOR ALL OF THE FORECAST AREA THAT HAS SNOW COVER OVER IT...FOR THE COMBINATION OF 25 TO 35 MPH SUSTAINED NW WINDS...BLOWING SNOW CONTINUING A HAZARDOUS TRAVEL SITUATION...AND WIND CHILLS THAT WILL DROP DOWN TO 20 BELOW TO 30 BELOW ZERO DURING THE AFTERNOON HOURS. ZONES WITHOUT ANY SUBSTANTIVE SNOW-COVER GET ANOTHER WIND ADVISORY FOR TODAY FOR 25 TO 35 MPH SUSTAINED WINDS WITH HIGHER GUSTS. ALSO...CLEANED UP SKY-COVER/WX/POP/SNW GRIDS AS RADAR/SAT TRENDS OVER THE PAST 2 TO 4 HOURS SUGGESTS THE BULK OF LIGHT SNOW FLURRY/SHOWER ACTIVITY IS PRETTY MUCH PASSED. LARGE AREA OF CLEARING OVER NORTH DAKOTA IS MOVING INTO NORTHEAST SOUTH DAKOTA. HOWEVER...LOW CLOUDS REMAIN ACROSS CENTRAL AND NORTH CENTRAL SODAK...SO CONTINUED SCATTERED FLURRY MENTION THROUGH THE REMAINDER OF THE TODAY PERIOD. LOW LEVEL THERMAL ADVECTION PATTERN FOR THE REMAINDER OF TODAY PERIOD IN THE RUC AND 12Z NAM-WRF SUGGEST 925HPA TEMPS DOWN TO -17C TO -20C ACROSS NE SODAK AND WC MN BY 00Z THIS EVENING...WHILE CENTRAL/NC SODAK APPEARS A LITTLE WARMER WITH 925HPA TEMPS RANGING FROM AROUND -10C TO -16C. THIS WILL PLAY A ROLE IN COMBINATION WITH WIND SPEEDS DURING THE TONIGHT PERIOD WHEN DETERMINING THE AREAL COVERAGE OF A WIND CHILL ADVISORY THAT WILL LIKELY BE POSTED FOR TONIGHT...LATER THIS AFTERNOON WITH THE AFTERNOON PACKAGE. STAY TUNED. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY NIGHT SHORT RANGE MODELS IN GOOD AGREEMENT. PROBLEM AREAS THIS CYCLE SEEM TO BE TEMPERATURES AND CHANCE OF PRECIPITATION. TEMPERATURES ACROSS THE AREA THIS MORNING ARE RUNNING IN THE UPPER TEENS TO LOW TWENTIES. TEMPERATURES IN NORTHERN NORTH DAKOTA ARE NEARLY TWENTY DEGREES COOLER. EXPECT THAT TODAY`S HIGH TEMPERATURE WILL OCCUR BEFORE 8 AM CST. GUSTY NORTH WINDS ARE ALSO NOTED ALTHOUGH THEY SHOULD STAY BELOW ADVISORY CRITERIA TODAY. WSR-88D SHOWING A LARGE AREA OF SPOTTY LIGHT RETURNS. EXPECT THIS WILL BE THE CASE MOST OF THE DAY. MODEL TIME HEIGHT CROSS SECTIONS SHOW AROUND 10C COOLER TEMPERATURES AT H85 THAN YESTERDAY EVENING. WIND CHILL VALUES WILL HOVER NEAR ADVISORY NUMBERS LATE TONIGHT AND TOMORROW BUT THE WIND IS JUST A LITTLE TOO LIGHT AT THIS TIME. THIS WILL NEED TO BE WATCHED. PRECIPITATION WILL BE HIT OR MISS TODAY AND MORE ALONG THE LINES OF FLURRIES. THE INCOMING AIR IS SO COLD THAT IT CAN NOT CARRY A GREAT AMOUNT OF MOISTURE. MONDAY WILL SEE ANOTHER WAVE APPROACH IN THE NORTHWEST FLOW. THE SURFACE LOW ASSOCIATED WITH THIS WAVE WILL ARRIVE SUNDAY. IT APPEARS THIS SYSTEM WILL HAVE MORE MOISTURE TO WORK WITH ALTHOUGH STILL NOT A GREAT AMOUNT. HELD OFF PRECIPITATION TIMING UNTIL THE UPPER WAVE WAS CLOSER TO THE AREA. EXPECT DURING THE DAY MONDAY WILL SEE SOME SNOW ALTHOUGH IT DOES NOT APPEAR TO BE A MAJOR EVENT BUT LIGHT FLUFFY SNOW WITH A LOW WATER EQUIVALENT AND 15 TO 20 MPH WIND MAY BE ENOUGH TO BE INCONVENIENT. .LONG TERM...TUESDAY THROUGH FRIDAY NOT MANY CHANGES MADE TO THE EXTENDED PERIOD AS THE COLD AND BREEZY WEATHER PATTERN WILL PERSIST THROUGH THE ENTIRE PERIOD. A COUPLE WAVES MOVE SOUTH THROUGH THE AREA IN NORTHERLY FLOW WITH THE BEST LOOKING SYSTEM TUESDAY NIGHT AND WEDNESDAY. SLIGHT CHANCE POPS STILL APPEAR OK ON WEDNESDAY...ALTHOUGH GFS IS SUGGESTING BEST LIFT MOVING THROUGH TUESDAY NIGHT. DECIDED TO KEEP TUESDAY NIGHT DRY FOR NOW TO SEE IF MODELS CONTINUE TO BRING BEST LIFT THROUGH DURING THIS TIME. IN FAST NORTHERLY FLOW DON`T HAVE VERY HIGH CONFIDENCE IN TIMING THE ONE OF MANY WAVES THAT MOVE SOUTH THROUGH THE AREA. MODELS STILL SUGGESTING EVEN COLDER AIR FOR LATE NEXT WEEK AS 850 MB TEMPS APPROACHING -30 C SURGE SOUTH INTO THE DAKOTAS. THIS WILL ALL DEPEND ON EXACT LOCATION OF HUDSON BAY LOW BUT DECENT AGREEMENT EXISTS IN BRINGING THIS SHOT OF COLDER AIR AT THIS TIME. COULD POTENTIALLY BE LOOKING AT LOWS WELL INTO THE TEENS AND 20S BELOW ZERO BY THE END OF NEXT WEEK AND INTO NEXT WEEKEND. && .AVIATION... 18Z TAFS ARE OUT...WITH THE PRIMARY FOCUS/CONCERN BEING THE STRONG NORTHWEST WINDS PREVALENT AGAIN TODAY ACROSS ALL FOUR TERMINALS. NORTHWEST WINDS SUSTAINED AROUND 30 MPH WITH HIGHER GUSTS WILL PERSIST THROUGH LATE THIS AFTERNOON. THEN...AS SURFACE HIGH PRESSURE CONTINUES TO REPOSITION ITSELF OVER THE NORTHERN AND CENTRAL PLAINS...WINDS DURING THE OVERNIGHT WILL GRADUALLY DROP OFF TO 10 TO 15 MPH AND SHIFT AROUND TO THE SOUTHWEST BY SUNDAY MORNING. SOME SCATTERED TO BROKEN MAINLY VFR CIGS /SCT-BKN045 AGL/ PERSIST ACROSS THE KMBG AND KPIR TERMINALS AND SUSPECT THEY WILL GRADUALLY DIMINISH THROUGH THE COURSE OF THIS AFTERNOON AND THIS EVENING. KABR AND KATY HAVE SCATTERED OUT...WITH THE EXPECTATION THAT SKC- SCT035 AGL CONDITIONS WILL PERSIST THROUGH TONIGHT. HOWEVER...ISOLATED INSTANCES OF MVFR CIG OR VIS CONDITIONS IN SNOW FLURRIES AND/OR BLSN ARE NOT OUT OF THE REALM OF POSSIBILITY THIS AFTERNOON...UNTIL THE CLOUDS CLEAR OUT AND THE WIND SPEEDS DIMINISH. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BROWN- CAMPBELL-CLARK-CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-GRANT- HAMLIN-HAND-HYDE-MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK- SULLY-WALWORTH. WIND ADVISORY UNTIL 4 PM CST /3 PM MST/ THIS AFTERNOON FOR BUFFALO-CORSON-DEWEY-HUGHES-JONES-LYMAN-STANLEY. MN...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BIG STONE-TRAVERSE. && $$ UPDATE...DORN SHORT TERM...KEEFE LONG TERM...TARVER AVIATION...DORN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1132 AM CST SAT JAN 27 2007 .UPDATE...TODAY HAVE MADE SOME CONSIDERABLE REVISIONS TO THE FORECAST PACKAGE WITH ADVISORY CRITERIA WINDS AGAIN BUFFETING THE FORECAST AREA TODAY. THE DIFFERENCE BETWEEN YESTERDAY AND TODAY IS THE ADDITIONAL LIGHT SNOWFALL AND BLOWING SNOW COMBINED WITH MUCH COLDER AIR IN PLACE TODAY THAN YESTERDAY...WHICH IS YIELDING WIND CHILLS RIGHT AT OR JUST ABOVE WIND CHILL ADVISORY CRITERIA. REPORTS FROM AROUND THE AREA INDICATE THAT BLOWING SNOW OVER ROADS IS MAKING AN IMPACT ON TRAVEL...SO HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE REST OF TODAY /VALID TAIL 4 PM CST/ FOR ALL OF THE FORECAST AREA THAT HAS SNOW COVER OVER IT...FOR THE COMBINATION OF 25 TO 35 MPH SUSTAINED NW WINDS...BLOWING SNOW CONTINUING A HAZARDOUS TRAVEL SITUATION...AND WIND CHILLS THAT WILL DROP DOWN TO 20 BELOW TO 30 BELOW ZERO DURING THE AFTERNOON HOURS. ZONES WITHOUT ANY SUBSTANTIVE SNOW-COVER GET ANOTHER WIND ADVISORY FOR TODAY FOR 25 TO 35 MPH SUSTAINED WINDS WITH HIGHER GUSTS. ALSO...CLEANED UP SKY-COVER/WX/POP/SNW GRIDS AS RADAR/SAT TRENDS OVER THE PAST 2 TO 4 HOURS SUGGESTS THE BULK OF LIGHT SNOW FLURRY/SHOWER ACTIVITY IS PRETTY MUCH PASSED. LARGE AREA OF CLEARING OVER NORTH DAKOTA IS MOVING INTO NORTHEAST SOUTH DAKOTA. HOWEVER...LOW CLOUDS REMAIN ACROSS CENTRAL AND NORTH CENTRAL SODAK...SO CONTINUED SCATTERED FLURRY MENTION THROUGH THE REMAINDER OF THE TODAY PERIOD. LOW LEVEL THERMAL ADVECTION PATTERN FOR THE REMAINDER OF TODAY PERIOD IN THE RUC AND 12Z NAM-WRF SUGGEST 925HPA TEMPS DOWN TO -17C TO -20C ACROSS NE SODAK AND WC MN BY 00Z THIS EVENING...WHILE CENTRAL/NC SODAK APPEARS A LITTLE WARMER WITH 925HPA TEMPS RANGING FROM AROUND -10C TO -16C. THIS WILL PLAY A ROLE IN COMBINATION WITH WIND SPEEDS DURING THE TONIGHT PERIOD WHEN DETERMINING THE AREAL COVERAGE OF A WIND CHILL ADVISORY THAT WILL LIKELY BE POSTED FOR TONIGHT...LATER THIS AFTERNOON WITH THE AFTERNOON PACKAGE. STAY TUNED. && .PREV DISCUSSION... .SHORT TERM...TODAY THROUGH MONDAY NIGHT SHORT RANGE MODELS IN GOOD AGREEMENT. PROBLEM AREAS THIS CYCLE SEEM TO BE TEMPERATURES AND CHANCE OF PRECIPITATION. TEMPERATURES ACROSS THE AREA THIS MORNING ARE RUNNING IN THE UPPER TEENS TO LOW TWENTIES. TEMPERATURES IN NORTHERN NORTH DAKOTA ARE NEARLY TWENTY DEGREES COOLER. EXPECT THAT TODAY`S HIGH TEMPERATURE WILL OCCUR BEFORE 8 AM CST. GUSTY NORTH WINDS ARE ALSO NOTED ALTHOUGH THEY SHOULD STAY BELOW ADVISORY CRITERIA TODAY. WSR-88D SHOWING A LARGE AREA OF SPOTTY LIGHT RETURNS. EXPECT THIS WILL BE THE CASE MOST OF THE DAY. MODEL TIME HEIGHT CROSS SECTIONS SHOW AROUND 10C COOLER TEMPERATURES AT H85 THAN YESTERDAY EVENING. WIND CHILL VALUES WILL HOVER NEAR ADVISORY NUMBERS LATE TONIGHT AND TOMORROW BUT THE WIND IS JUST A LITTLE TOO LIGHT AT THIS TIME. THIS WILL NEED TO BE WATCHED. PRECIPITATION WILL BE HIT OR MISS TODAY AND MORE ALONG THE LINES OF FLURRIES. THE INCOMING AIR IS SO COLD THAT IT CAN NOT CARRY A GREAT AMOUNT OF MOISTURE. MONDAY WILL SEE ANOTHER WAVE APPROACH IN THE NORTHWEST FLOW. THE SURFACE LOW ASSOCIATED WITH THIS WAVE WILL ARRIVE SUNDAY. IT APPEARS THIS SYSTEM WILL HAVE MORE MOISTURE TO WORK WITH ALTHOUGH STILL NOT A GREAT AMOUNT. HELD OFF PRECIPITATION TIMING UNTIL THE UPPER WAVE WAS CLOSER TO THE AREA. EXPECT DURING THE DAY MONDAY WILL SEE SOME SNOW ALTHOUGH IT DOES NOT APPEAR TO BE A MAJOR EVENT BUT LIGHT FLUFFY SNOW WITH A LOW WATER EQUIVALENT AND 15 TO 20 MPH WIND MAY BE ENOUGH TO BE INCONVENIENT. .LONG TERM...TUESDAY THROUGH FRIDAY NOT MANY CHANGES MADE TO THE EXTENDED PERIOD AS THE COLD AND BREEZY WEATHER PATTERN WILL PERSIST THROUGH THE ENTIRE PERIOD. A COUPLE WAVES MOVE SOUTH THROUGH THE AREA IN NORTHERLY FLOW WITH THE BEST LOOKING SYSTEM TUESDAY NIGHT AND WEDNESDAY. SLIGHT CHANCE POPS STILL APPEAR OK ON WEDNESDAY...ALTHOUGH GFS IS SUGGESTING BEST LIFT MOVING THROUGH TUESDAY NIGHT. DECIDED TO KEEP TUESDAY NIGHT DRY FOR NOW TO SEE IF MODELS CONTINUE TO BRING BEST LIFT THROUGH DURING THIS TIME. IN FAST NORTHERLY FLOW DON`T HAVE VERY HIGH CONFIDENCE IN TIMING THE ONE OF MANY WAVES THAT MOVE SOUTH THROUGH THE AREA. MODELS STILL SUGGESTING EVEN COLDER AIR FOR LATE NEXT WEEK AS 850 MB TEMPS APPROACHING -30 C SURGE SOUTH INTO THE DAKOTAS. THIS WILL ALL DEPEND ON EXACT LOCATION OF HUDSON BAY LOW BUT DECENT AGREEMENT EXISTS IN BRINGING THIS SHOT OF COLDER AIR AT THIS TIME. COULD POTENTIALLY BE LOOKING AT LOWS WELL INTO THE TEENS AND 20S BELOW ZERO BY THE END OF NEXT WEEK AND INTO NEXT WEEKEND. && .AVIATION... BKN CLOUD DECK CONTINUES TO MOVE SOUTH OVER NORTH DAKOTA AND SOUTH DAKOTA THIS MORNING. SCT -SHSN AND AREAS OF BLSN ALSO EXPECTED ACROSS PORTIONS OF CENTRAL AND EASTERN SOUTH DAKOTA...AS WELL AS SOUTHERN NORTH DAKOTA. CEILINGS GENERALLY RANGE FROM 2000-6000 FT BUT WILL BE LOW END MVFR AROUND 1000 FT IN -SHSN. VISIBILITIES WILL BE REDUCED TO AROUND 1SM AT TIMES IN -SHSN. SURFACE WINDS FROM THE NORTHWEST 20 TO 30 MPH DURING THE MORNING AND EARLY AFTERNOON. THESE CONDITIONS WILL PERSIST THROUGHOUT THE MORNING WITH AN IMPROVEMENT THIS AFTERNOON. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BROWN- CAMPBELL-CLARK-CODINGTON-DAY-DEUEL-EDMUNDS-FAULK-GRANT- HAMLIN-HAND-HYDE-MARSHALL-MCPHERSON-POTTER-ROBERTS-SPINK- SULLY-WALWORTH. WIND ADVISORY UNTIL 4 PM CST /3 PM MST/ THIS AFTERNOON FOR BUFFALO-CORSON-DEWEY-HUGHES-JONES-LYMAN-STANLEY. MN...WINTER WEATHER ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR BIG STONE-TRAVERSE. && $$ UPDATE...DORN SHORT TERM...KEEFE LONG TERM...TARVER AVIATION...TARVER sd