Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 03/08/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1103 AM MST WED MAR 6 2013 .UPDATE...AMENDED THE ZONES FOR SLIGHTLY COOLER TEMPERATURES ON PLAINS TODAY...AND STRONGER SOUTHEAST WINDS FAR NORTHEAST PLAINS. && .AVIATION...SOUTHEAST TO NORTHEAST WINDS TODAY WILL GIVE WAY TO DRAINAGE WINDS TONIGHT. && .PREV DISCUSSION... /ISSUED 1000 AM MST WED MAR 6 2013/ UPDATE...WILL CLOSELY WATCH MIXING TODAY...MID SHIFT DID DELINIATE FOR SNOW ON GROUND WITH COOLER MAXES FROM SOUTHERN WELD TO NORTHEASTERN ELBERT COUNTIES. THERE IS ALSO SOME CLOUDS TO ACCOUNT FOR IN THESE AREAS. OTHERWISE NO CHANGES EXPECTED. AVIATION...A BIT OF HAZE AT KDIA WILL DISSIPATE WITH MIXING TODAY...SO LOOKING FOR DRY VFR CONDITIONS WITH LIGHT WINDS. PREV DISCUSSION... /ISSUED 408 AM MST WED MAR 6 2013/ SHORT TERM...SWLY FLOW ALOFT WILL DEVELOP OVER THE AREA AS THE UPPER LEVEL RIDGE SHIFTS EAST. SOME HIGHER LEVEL CLOUDS WILL BE POSSIBLE OTHERWISE IT WILL REMAIN DRY THRU TONIGHT. ONCE AGAIN HIGH TEMPS THIS AFTN WILL BE THE MAIN ISSUE. SOME DEEPER SNOW COVER STILL RESIDES OVER SRN WELD...CNTRL AND ERN PORTIONS OF ADAMS AND ARAPAHOE ALONG WITH ELBERT COUNTIES WHICH WILL AFFECT AFTN HIGHS IN THESE AREAS AS READINGS MAY NOT GET OUT OF THE 40S. MEANWHILE NR THE FOOTHILLS LIGHT WLY DOWNSLOPE FLOW WILL DVLP WHICH MAY ALLOW FOR HIGHS TO REACH THE LOWER 60S OVER THE WRN AND SRN SUBURBS OF DENVER. THUS WILL SEE QUITE A TEMP DIFFERENCE ALONG THE FRONT RANGE THIS AFTN. OVER THE PLAINS WHERE NO SNOW COVER EXISTS WINDS WILL BE MAINLY SELY SO WILL KEEP AFTN HIGHS IN THE LOWER TO MID 50S EXCEPT OVER SRN LINCOLN COUNTY WHERE LOWER 60S WILL BE POSSIBLE DUE TO SWLY LOW LVL WINDS. FOR TONIGHT MAY SEE SOME PATCHY FOG DVLP OVER THE FAR NERN PLAINS AFTER MIDNIGHT. LONG TERM...THURSDAY WILL BE DRY AND WARM AS SOUTHWESTERLY FLOW ALOFT COVERS THE STATE. FRIDAY WILL BE A TRANSITIONAL DAY AS SOUTHWEST FLOW ALOFT CONTINUES BUT MOISTURE BEGINS INCREASING AHEAD OF A POTENT UPPER LOW MOVING OVER THE DESERT SOUTHWEST. AND SATURDAY LOOKS LIKE IT WILL BE THE MOST CRITICAL DAY OF THIS FORECAST PACKAGE. EACH OF THE SYNOPTIC MODELS SHOW THE STRONG UPPER LEVEL LOW PRESSURE SYSTEM MOVING ACROSS OR NEAR THE FOUR CORNERS AREA ON SATURDAY...SETTING UP A SNOW PATTERN FOR NORTHEAST COLORADO. HOWEVER...AGREEMENT BETWEEN THE MODELS IS FAR FROM UNANIMOUS. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF AND THE NAM ONLY GOES OUT TO MIDDAY SATURDAY BUT SHOWS AGREEMENT WITH THE GFS. PRECIPITATION AMOUNTS ALSO VARY BETWEEN THE DIFFERENT MODELS. THE NAM SHOWS AN INITIALLY DRY SWATH OF AIR MOVING ACROSS THE EASTERN PLAINS WITH THE EJECTING UPPER LOW...WHILE THE GFS GENERATES COPIOUS AMOUNTS OF SNOWFALL. THE ECMWF SHOWS ONLY LIGHT TO MODERATE SNOW AMOUNTS THROUGH SATURDAY NIGHT. NEEDLESS TO SAY...MANY QUESTIONS STILL REMAIN ON HOW BIG THIS STORM IS GOING TO BE. THE STORM SYSTEM...WHICH IS CURRENTLY DEVELOPING OFF THE COAST OF OREGON IS GOING TO CONTAIN A LOT OF COLD AIR ALOFT AND WILL ALSO ENCOUNTER A GOOD SHOT OF LOW LEVEL MOISTURE FROM THE GULF OF MEXICO WHEN IT MOVES ACROSS COLORADO. MODEL SOUNDINGS SHOW LAPSE RATES SATURDAY AFTERNOON WILL BE NEARLY MOIST ADIABATIC DUE TO THE COLD TEMPERATURES ALOFT. IF THE SYSTEM TAKES ITS TIME MOVING ACROSS COLORADO...SIMILAR TO THE ECMWF SOLUTION...THEN IT WILL BE ABLE TO PRODUCE SNOW AMOUNTS HEAVIER THAN WHAT THE ECMWF CONTAINS. THE TIMING OF THE GFS AND NAM SOLUTIONS MAY WELL END UP BEING TOO FAST AS THE SYSTEM ALREADY LOOKS LIKE IT IS READY TO CUTOFF FROM THE NORTHERN STREAM IN THE NEXT 24 TO 36 HOURS. GIVEN ALL THE UNCERATINTY...IT IS TOO EARLY TO ISSUE ANY HIGHLIGHTS... BUT THAT MAY CHANGE LATER TODAY OR TONIGHT. ALONG WITH THE UPPER DYNAMICS OF THE PASSING UPPER LOW ON SATURDAY...IT LOOKS LIKE A STRONG SURGE OF NORTHERLY SURFACE WINDS WILL DEVELOP SATURDAY AFTERNOON ON THE BACK SIDE OF THE STORM. HAVE ADDED AREAS OF BLOWING SNOW TO THE SATURDAY AFTERNOON AND EVENING FORECAST. FOR SUNDAY THROUGH TUESDAY...MODELS SHOW COLORADO UNDER NORTHWEST FLOW WITH WARMER TEMPERATURES AND DRIER CONDITIONS. TEMPERATURE FORECASTS FOR THESE DAYS IS GOING TO BE VERY DEPENDENT ON HOW MUCH SNOW FALLS DURING THE SATURDAY THROUGH SUNDAY PERIOD. FOR THE TIME BEING...WILL KEEP THIS PART OF THE FORECAST VERY GENERAL. AVIATION...VFR THRU TONIGHT. WK SFC LOW PRES WILL LIKELY REMAIN WEST OF THE AIRPORT THRU THIS AFTN. OVERALL THE HRRR AND RAP KEEP WINDS LIGHT SSW THRU LATE MORNING AND THEN GRADUALLY SHIFTTHEN MORE ELY BY EARLY AFTN. THE ELY WINDS ARE FCST TO STAY IN PLACE AT LEAST THRU 23Z BEFORE BECOMING MORE SELY BY 01Z. WINDS WILL THEN GRADUALLY BECOME DRAINAGE BY 03Z AND CONTINUE THAT WAY OVERNIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RTG LONG TERM....99 AVIATION...RTG
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1000 AM MST WED MAR 6 2013 .UPDATE...WILL CLOSELY WATCH MIXING TODAY...MID SHIFT DID DELINIATE FOR SNOW ON GROUND WITH COOLER MAXES FROM SOUTHERN WELD TO NORTHEASTERN ELBERT COUNTIES. THERE IS ALSO SOME CLOUDS TO ACCOUNT FOR IN THESE AREAS. OTHERWISE NO CHANGES EXPECTED. && .AVIATION...A BIT OF HAZE AT KDIA WILL DISSIPATE WITH MIXING TODAY...SO LOOKING FOR DRY VFR CONDITIONS WITH LIGHT WINDS. && .PREV DISCUSSION... /ISSUED 408 AM MST WED MAR 6 2013/ SHORT TERM...SWLY FLOW ALOFT WILL DEVELOP OVER THE AREA AS THE UPPER LEVEL RIDGE SHIFTS EAST. SOME HIGHER LEVEL CLOUDS WILL BE POSSIBLE OTHERWISE IT WILL REMAIN DRY THRU TONIGHT. ONCE AGAIN HIGH TEMPS THIS AFTN WILL BE THE MAIN ISSUE. SOME DEEPER SNOW COVER STILL RESIDES OVER SRN WELD...CNTRL AND ERN PORTIONS OF ADAMS AND ARAPAHOE ALONG WITH ELBERT COUNTIES WHICH WILL AFFECT AFTN HIGHS IN THESE AREAS AS READINGS MAY NOT GET OUT OF THE 40S. MEANWHILE NR THE FOOTHILLS LIGHT WLY DOWNSLOPE FLOW WILL DVLP WHICH MAY ALLOW FOR HIGHS TO REACH THE LOWER 60S OVER THE WRN AND SRN SUBURBS OF DENVER. THUS WILL SEE QUITE A TEMP DIFFERENCE ALONG THE FRONT RANGE THIS AFTN. OVER THE PLAINS WHERE NO SNOW COVER EXISTS WINDS WILL BE MAINLY SELY SO WILL KEEP AFTN HIGHS IN THE LOWER TO MID 50S EXCEPT OVER SRN LINCOLN COUNTY WHERE LOWER 60S WILL BE POSSIBLE DUE TO SWLY LOW LVL WINDS. FOR TONIGHT MAY SEE SOME PATCHY FOG DVLP OVER THE FAR NERN PLAINS AFTER MIDNIGHT. LONG TERM...THURSDAY WILL BE DRY AND WARM AS SOUTHWESTERLY FLOW ALOFT COVERS THE STATE. FRIDAY WILL BE A TRANSITIONAL DAY AS SOUTHWEST FLOW ALOFT CONTINUES BUT MOISTURE BEGINS INCREASING AHEAD OF A POTENT UPPER LOW MOVING OVER THE DESERT SOUTHWEST. AND SATURDAY LOOKS LIKE IT WILL BE THE MOST CRITICAL DAY OF THIS FORECAST PACKAGE. EACH OF THE SYNOPTIC MODELS SHOW THE STRONG UPPER LEVEL LOW PRESSURE SYSTEM MOVING ACROSS OR NEAR THE FOUR CORNERS AREA ON SATURDAY...SETTING UP A SNOW PATTERN FOR NORTHEAST COLORADO. HOWEVER...AGREEMENT BETWEEN THE MODELS IS FAR FROM UNANIMOUS. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF AND THE NAM ONLY GOES OUT TO MIDDAY SATURDAY BUT SHOWS AGREEMENT WITH THE GFS. PRECIPITATION AMOUNTS ALSO VARY BETWEEN THE DIFFERENT MODELS. THE NAM SHOWS AN INITIALLY DRY SWATH OF AIR MOVING ACROSS THE EASTERN PLAINS WITH THE EJECTING UPPER LOW...WHILE THE GFS GENERATES COPIOUS AMOUNTS OF SNOWFALL. THE ECMWF SHOWS ONLY LIGHT TO MODERATE SNOW AMOUNTS THROUGH SATURDAY NIGHT. NEEDLESS TO SAY...MANY QUESTIONS STILL REMAIN ON HOW BIG THIS STORM IS GOING TO BE. THE STORM SYSTEM...WHICH IS CURRENTLY DEVELOPING OFF THE COAST OF OREGON IS GOING TO CONTAIN A LOT OF COLD AIR ALOFT AND WILL ALSO ENCOUNTER A GOOD SHOT OF LOW LEVEL MOISTURE FROM THE GULF OF MEXICO WHEN IT MOVES ACROSS COLORADO. MODEL SOUNDINGS SHOW LAPSE RATES SATURDAY AFTERNOON WILL BE NEARLY MOIST ADIABATIC DUE TO THE COLD TEMPERATURES ALOFT. IF THE SYSTEM TAKES ITS TIME MOVING ACROSS COLORADO...SIMILAR TO THE ECMWF SOLUTION...THEN IT WILL BE ABLE TO PRODUCE SNOW AMOUNTS HEAVIER THAN WHAT THE ECMWF CONTAINS. THE TIMING OF THE GFS AND NAM SOLUTIONS MAY WELL END UP BEING TOO FAST AS THE SYSTEM ALREADY LOOKS LIKE IT IS READY TO CUTOFF FROM THE NORTHERN STREAM IN THE NEXT 24 TO 36 HOURS. GIVEN ALL THE UNCERATINTY...IT IS TOO EARLY TO ISSUE ANY HIGHLIGHTS... BUT THAT MAY CHANGE LATER TODAY OR TONIGHT. ALONG WITH THE UPPER DYNAMICS OF THE PASSING UPPER LOW ON SATURDAY...IT LOOKS LIKE A STRONG SURGE OF NORTHERLY SURFACE WINDS WILL DEVELOP SATURDAY AFTERNOON ON THE BACK SIDE OF THE STORM. HAVE ADDED AREAS OF BLOWING SNOW TO THE SATURDAY AFTERNOON AND EVENING FORECAST. FOR SUNDAY THROUGH TUESDAY...MODELS SHOW COLORADO UNDER NORTHWEST FLOW WITH WARMER TEMPERATURES AND DRIER CONDITIONS. TEMPERATURE FORECASTS FOR THESE DAYS IS GOING TO BE VERY DEPENDENT ON HOW MUCH SNOW FALLS DURING THE SATURDAY THROUGH SUNDAY PERIOD. FOR THE TIME BEING...WILL KEEP THIS PART OF THE FORECAST VERY GENERAL. AVIATION...VFR THRU TONIGHT. WK SFC LOW PRES WILL LIKELY REMAIN WEST OF THE AIRPORT THRU THIS AFTN. OVERALL THE HRRR AND RAP KEEP WINDS LIGHT SSW THRU LATE MORNING AND THEN GRADUALLY SHIFTTHEN MORE ELY BY EARLY AFTN. THE ELY WINDS ARE FCST TO STAY IN PLACE AT LEAST THRU 23Z BEFORE BECOMING MORE SELY BY 01Z. WINDS WILL THEN GRADUALLY BECOME DRAINAGE BY 03Z AND CONTINUE THAT WAY OVERNIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RTG LONG TERM....99 AVIATION...RTG
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
408 AM MST WED MAR 6 2013 .SHORT TERM...SWLY FLOW ALOFT WILL DEVELOP OVER THE AREA AS THE UPPER LEVEL RIDGE SHIFTS EAST. SOME HIGHER LEVEL CLOUDS WILL BE POSSIBLE OTHERWISE IT WILL REMAIN DRY THRU TONIGHT. ONCE AGAIN HIGH TEMPS THIS AFTN WILL BE THE MAIN ISSUE. SOME DEEPER SNOW COVER STILL RESIDES OVER SRN WELD...CNTRL AND ERN PORTIONS OF ADAMS AND ARAPAHOE ALONG WITH ELBERT COUNTIES WHICH WILL AFFECT AFTN HIGHS IN THESE AREAS AS READINGS MAY NOT GET OUT OF THE 40S. MEANWHILE NR THE FOOTHILLS LIGHT WLY DOWNSLOPE FLOW WILL DVLP WHICH MAY ALLOW FOR HIGHS TO REACH THE LOWER 60S OVER THE WRN AND SRN SUBURBS OF DENVER. THUS WILL SEE QUITE A TEMP DIFFERENCE ALONG THE FRONT RANGE THIS AFTN. OVER THE PLAINS WHERE NO SNOW COVER EXISTS WINDS WILL BE MAINLY SELY SO WILL KEEP AFTN HIGHS IN THE LOWER TO MID 50S EXCEPT OVER SRN LINCOLN COUNTY WHERE LOWER 60S WILL BE POSSIBLE DUE TO SWLY LOW LVL WINDS. FOR TONIGHT MAY SEE SOME PATCHY FOG DVLP OVER THE FAR NERN PLAINS AFTER MIDNIGHT. .LONG TERM...THURSDAY WILL BE DRY AND WARM AS SOUTHWESTERLY FLOW ALOFT COVERS THE STATE. FRIDAY WILL BE A TRANSITIONAL DAY AS SOUTHWEST FLOW ALOFT CONTINUES BUT MOISTURE BEGINS INCREASING AHEAD OF A POTENT UPPER LOW MOVING OVER THE DESERT SOUTHWEST. AND SATURDAY LOOKS LIKE IT WILL BE THE MOST CRITICAL DAY OF THIS FORECAST PACKAGE. EACH OF THE SYNOPTIC MODELS SHOW THE STRONG UPPER LEVEL LOW PRESSURE SYSTEM MOVING ACROSS OR NEAR THE FOUR CORNERS AREA ON SATURDAY...SETTING UP A SNOW PATTERN FOR NORTHEAST COLORADO. HOWEVER...AGREEMENT BETWEEN THE MODELS IS FAR FROM UNANIMOUS. THE GFS IS MORE PROGRESSIVE THAN THE ECMWF AND THE NAM ONLY GOES OUT TO MIDDAY SATURDAY BUT SHOWS AGREEMENT WITH THE GFS. PRECIPITATION AMOUNTS ALSO VARY BETWEEN THE DIFFERENT MODELS. THE NAM SHOWS AN INITIALLY DRY SWATH OF AIR MOVING ACROSS THE EASTERN PLAINS WITH THE EJECTING UPPER LOW...WHILE THE GFS GENERATES COPIOUS AMOUNTS OF SNOWFALL. THE ECMWF SHOWS ONLY LIGHT TO MODERATE SNOW AMOUNTS THROUGH SATURDAY NIGHT. NEEDLESS TO SAY...MANY QUESTIONS STILL REMAIN ON HOW BIG THIS STORM IS GOING TO BE. THE STORM SYSTEM...WHICH IS CURRENTLY DEVELOPING OFF THE COAST OF OREGON IS GOING TO CONTAIN A LOT OF COLD AIR ALOFT AND WILL ALSO ENCOUNTER A GOOD SHOT OF LOW LEVEL MOISTURE FROM THE GULF OF MEXICO WHEN IT MOVES ACROSS COLORADO. MODEL SOUNDINGS SHOW LAPSE RATES SATURDAY AFTERNOON WILL BE NEARLY MOIST ADIABATIC DUE TO THE COLD TEMPERATURES ALOFT. IF THE SYSTEM TAKES ITS TIME MOVING ACROSS COLORADO...SIMILAR TO THE ECMWF SOLUTION...THEN IT WILL BE ABLE TO PRODUCE SNOW AMOUNTS HEAVIER THAN WHAT THE ECMWF CONTAINS. THE TIMING OF THE GFS AND NAM SOLUTIONS MAY WELL END UP BEING TOO FAST AS THE SYSTEM ALREADY LOOKS LIKE IT IS READY TO CUTOFF FROM THE NORTHERN STREAM IN THE NEXT 24 TO 36 HOURS. GIVEN ALL THE UNCERATINTY...IT IS TOO EARLY TO ISSUE ANY HIGHLIGHTS... BUT THAT MAY CHANGE LATER TODAY OR TONIGHT. ALONG WITH THE UPPER DYNAMICS OF THE PASSING UPPER LOW ON SATURDAY...IT LOOKS LIKE A STRONG SURGE OF NORTHERLY SURFACE WINDS WILL DEVELOP SATURDAY AFTERNOON ON THE BACK SIDE OF THE STORM. HAVE ADDED AREAS OF BLOWING SNOW TO THE SATURDAY AFTERNOON AND EVENING FORECAST. FOR SUNDAY THROUGH TUESDAY...MODELS SHOW COLORADO UNDER NORTHWEST FLOW WITH WARMER TEMPERATURES AND DRIER CONDITIONS. TEMPERATURE FORECASTS FOR THESE DAYS IS GOING TO BE VERY DEPENDENT ON HOW MUCH SNOW FALLS DURING THE SATURDAY THROUGH SUNDAY PERIOD. FOR THE TIME BEING...WILL KEEP THIS PART OF THE FORECAST VERY GENERAL. && .AVIATION...VFR THRU TONIGHT. WK SFC LOW PRES WILL LIKELY REMAIN WEST OF THE AIRPORT THRU THIS AFTN. OVERALL THE HRRR AND RAP KEEP WINDS LIGHT SSW THRU LATE MORNING AND THEN GRADUALLY SHIFTTHEN MORE ELY BY EARLY AFTN. THE ELY WINDS ARE FCST TO STAY IN PLACE AT LEAST THRU 23Z BEFORE BECOMING MORE SELY BY 01Z. WINDS WILL THEN GRADUALLY BECOME DRAINAGE BY 03Z AND CONTINUE THAT WAY OVERNIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...RPK LONG TERM....DANKERS AVIATION...RPK
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
958 PM EST THU MAR 7 2013 .SYNOPSIS... AN UPPER LEVEL DISTURBANCE WILL SLIDE ACROSS THE AREA OVERNIGHT INTO FRIDAY MORNING. HIGH PRESSURE WILL GRADUALLY BUILD INTO THE REGION ON SATURDAY, SETTLE OVER THE AREA ON SUNDAY AND THEN SLIDE OFFSHORE. A LOW PRESSURE SYSTEM WILL MOVE IN FROM THE WEST EARLY IN THE WEEK, DRAGGING A COLD FRONT ACROSS THE AREA ON TUESDAY. A SECONDARY FRONT MAY CROSS THE REGION WEDNESDAY NIGHT INTO EARLY THURSDAY. HIGH PRESSURE WILL THEN BUILD IN FROM THE WEST FOR THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... WHILE NONE OF THE MODELS HAD THE BANDED PRECIPITATION SPOT ON, THE GFS OVERALL LOOKED CLOSER IN THE 6 HR PERIOD ENDING AT 00Z. HARD TO SAY COMPLETELY BUT THE GFS LOOKED BEST OVERALL WITH THE AREAL EXTENT AND AMOUNTS EXCEPT FOR CAPE COD WHERE THE WRF-NMMB WAS BETTER. THE 500MB INITIALIZATION OF THE 00Z WRF-NMMB WAS A BIT TOO STRONG WITH THE 500MB FEATURES. THE LATEST RUN STARTS ENHANCING PRECIPITATION EAST OF BOSTON AND THEN PIVOTS IT INTO NEW JERSEY LATE TONIGHT AND ON FRIDAY MORNING. RIGHT NOW THE IR CLOUDS ARE WARMING APPROACHING MASSACHUSETTS AND THEIR SFC VSBYS HAVE YET TO DROP. SO NOT CONFIDENT ABOUT THAT ENHANCED PCPN WORKING TO THAT EXTENT TO MAKE ANY SIGNIFICANT CHANGES. OTHERWISE THE 23Z HRRR LOOKED PRETTY GOOD WITH THE OVERALL RADAR DEPICTION AND THEY PIVOT PCPN INTO NEW JERSEY OVERNIGHT. NEAREST BAND HAS NOT DROPPED VSBYS MUCH IN NYC. SO THE POP DISTRIBUTION WAS ANGLED SLIGHTLY MORE NNW TO SSE THAN THE PREVIOUS PACKAGE. ACCUMS BASED ON SPOTTER REPORTS AND TRAFFIC CAMS SEEM TO BE MAINLY IN NORTHWEST NEW JERSEY. FARTHER SOUTH, WHILE SNOW HAS STARTED TO FALL, TEMPERATURES ARE STILL ABOVE FREEZING. DEW POINTS THOUGH ARE DROPPING AND WOULD EXPECT THE COATINGS AND ACCUMULATIONS TO START SPREADING SOUTH. THE GFS MID LEVEL QVEC CONVERGENCE WHICH ALSO WAS ALIGNING WELL WITH THE MORE ENHANCED ECHOES HAVE THE CORE MOVE THROUGH OUR CWA AROUND 12Z. SO IF THERE IS AN AREA OF CONCERN ABOUT GETTING TO ADVISORY LEVELS WOULD THINK MIDDLESEX, MONMOUTH AND OCEAN. FOR NOW WE ISSUED AN SPS ABOUT THE SNOW COMING IN TOWARD MORNING AND WILL SEE WHAT THE REST OF GUIDANCE SUITE SHOWS. WE REALLY DID NOT CHANGE TEMPERATURES MUCH, THEY LOOKED CLOSE. SOME UPWARD ADJUSTMENTS ON DEW POINTS WERE MADE. THE SECOND MID LEVEL WILL DROP DOWN FROM WRN NY THIS EVENING TO NEAR DOV BY DAYBREAK. THIS TIME, THE NAM HAS A LITTLE BIT OF COMPANY IN THIS PERIOD WITH THE MID LEVEL DYNAMICS, THE LOWER LEVEL FRONTOGENESIS AND THE MODEST TROWAL THAT PASS ACROSS US. WE ALREADY HAD AREAS OF LIGHT PRECIPITATION (MAINLY RAIN) OVER THE NORTHEASTERN HALF OF THE AREA, SO FOR TONIGHT WE BLENDED THE ECMWF, NAM AND GFS TO PRECIPITATION TO ARRIVE AT POPS THAT RANGE FROM SLIGHT CHANCE SOUTHWEST TO CATEGORICAL NORTHEAST. PRECIPITATION SHOULD CHANGE TO SNOW FROM NORTH TO SOUTH ACROSS THE AREA WHERE IT FALLS. THE QPF FORECAST IS NOT TERRIBLY ROBUST, SINCE NOT A LOT OF MOISTURE COMES WITH THIS SYSTEM. SNOWFALL AMOUNTS TONIGHT ARE FORECAST TO RANGE FROM UP TO FIVE INCHES ACROSS SUSSEX AND MORRIS COUNTIES TO LESS THAN AN INCH NEAR AND SOUTH OF THE I195 CORRIDOR OVER NJ, DE AND MD AND NEAR AND SOUTH OF A TTN TO ABE LINE OVER PA. WE WENT A LITTLE ON THE COOLER SIDE OF THE RANGE OF STAT GUIDANCE WITH THE MID LEVEL LOW DROPPING THROUGH THE AREA AND WITH PRECIPITATION EXPECTED OVER MUCH OF THE AREA. THE STEADY NORTHWEST FLOW WILL CONTINUE, AND MAY WELL KICK UP A BIT TOWARD DAYBREAK. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... THE MID LEVEL LOW WILL MOVE SOUTHEAST AND AWAY FROM THE AREA ON FRIDAY, AND PRECIPITATION WILL END FROM WEST TO EAST IN RESPONSE. NORTHEASTERN AND EAST CENTRAL AREAS WILL SEE A LITTLE BIT OF ADDITIONAL SNOW, BUT WE WILL BE DEALING WITH A MARCH SUN ANGLE THAT WILL TAMP DOWN ANY MORNING ACCUMULATIONS. WE END UP MAINTAINING THE ADVISORY OVER SUSSEX AND MORRIS COUNTIES AND NOT EXPANDING IT. THERE DOES NOT APPEAR TO BE ANY WINDEX ISSUE OR ANY LAKE EFFECT ISSUE. WE ARE IN THE MIDDLE TO LOW END OF STAT GUIDANCE ON TEMPERATURES. EXPECT ANOTHER BLUSTERY DAY. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... THE 500MB LOW STARTS TO MOVE OFF TO THE EAST BY LATE FRIDAY. AS THE LOW MOVES EASTWARD, WE WILL START TO SEE RIDGING OCCUR IN THE MID LEVELS, WHICH INDICATES A WARMING TREND INTO THE EXTENDED PERIOD ACROSS OUR REGION. ANOTHER MID LEVEL SYSTEM, DEVELOPS EARLY IN THE WEEK ACROSS THE CENTRAL UNITED STATES AND WE START TO SEE TROUGHING MOVE TOWARD THE EAST COAST ONCE AGAIN. THE MID LEVEL TROUGH DEEPENS AND MOVES ACROSS OUR REGION AROUND MIDWEEK. A MORE ZONAL FLOW IS EXPECTED TO DEVELOP CLOSER TO THE FOLLOWING WEEKEND. AT THE SURFACE, THE STRONG LOW PRESSURE SYSTEM WILL CONTINUE TO PULL OFF TOWARDS THE EAST, ALLOWING HIGH PRESSURE TO BUILD INTO THE MID-ATLANTIC REGION OVER THE WEEKEND. THE HIGH BUILDS IN FROM THE WEST ON SATURDAY BEFORE SLIDING ACROSS THE AREA ON SUNDAY, EVENTUALLY MOVING OFFSHORE BY LATE SUNDAY NIGHT. EXPECT DRY CONDITIONS THROUGH EARLY MONDAY AS THE HIGH AT THE SURFACE DOMINATES THE WEATHER ACROSS THE AREA. AS DRIER AIR MAKES ITS WAY INTO THE AREA, WE SHOULD LESS CLOUDS DEVELOP. THE PREVIOUSLY MENTIONED 500MB RIDGE WILL ALLOW FOR WARMING TO OCCUR. A SOUTHERLY FLOW DEVELOPS AT THE SURFACE ON SUNDAY AS THE SURFACE HIGH MOVES OFFSHORE AND THIS WILL JUST INCREASE THE WARMING ACROSS THE REGION. WE WILL SEE TEMPERATURES RISE WELL ABOVE NORMAL FOR AT LEAST A FEW DAYS. DAYTIME TEMPERATURES WILL BE IN THE UPPER 40S TO LOWER 50S ON SATURDAY BUT WILL RISE INTO THE MID 50S ON SUNDAY. THE HIGH SLIDES OFFSHORE SUNDAY NIGHT AND LOW PRESSURE OVER THE MIDWEST STARTS TO MOVE EASTWARD. CLOUDS WILL BEGIN TO INCREASE LATE SUNDAY AND CONTINUE TO INCREASE THROUGH MONDAY. THE LOW MOVES NORTHEASTWARD AND UP INTO NEW ENGLAND, DRAGGING A COLD FRONT INTO OUR AREA ON MONDAY NIGHT. THE FRONT EXTENDS WELL INTO THE SOUTHERN STATES AND LOOKS TO GATHER SOME OF ITS MOISTURE ALL THE WAY FROM THE GULF. A SECOND LOW DEVELOPS ALONG THE FRONTAL BOUNDARY AND THEN MOVES NORTHEASTWARD. THE MODELS DISAGREE ON JUST HOW FAST THE BOUNDARY MOVES TO THE EAST AND AS A RESULT THE SECOND LOW MAY END UP REMAINING TO THE SOUTH OF THE AREA AS IT MOVES NORTHEASTWARD. THEREFORE, WE OPTED TO MAKE FEW CHANGES TO THE CURRENT TIMING IN THE FORECAST. EITHER WAY, IT DOES APPEARS THAT THERE WILL BE RAIN ACROSS THE REGION MONDAY NIGHT AND TUESDAY AS THE FRONT CROSSES THE AREA. TEMPERATURES ALSO LOOK TO REMAIN WARM ENOUGH TO KEEP THE PRECIPITATION PRIMARILY RAIN ACROSS THE REGION. THE SURFACE LOW MOVES OFF INTO NEW ENGLAND ON TUESDAY AND BEGINS TO INTENSIFY. AS THE LOW DEEPENS, WE WILL START TO GET A PUSH OF COLD AIR INTO THE REGION ON THE CYCLONIC FLOW, BOTH AT THE SURFACE AND ALOFT. SHOULD THE NORTHWEST FLOW BE STRONG ENOUGH, WE CAN NOT RULE OUT THAT SOME LAKE EFFECT SNOW WILL MAKE IT INTO OUR NORTHWEST ZONES WHERE TEMPERATURES WILL REMAIN IN THE UPPER 30S TO LOWER 40S, ESPECIALLY ACROSS THE HIGHER TERRAIN. IF THE FLOW IS STRONG ENOUGH A FEW SPRINKLES OR LIGHT SHOWERS MAY MAKE IT FURTHER SOUTH AND EASTWARD, WHERE TEMPERATURES WILL LIKELY RISE INTO THE UPPER 40S TO LOWER 50S. HIGH PRESSURE WILL THEN BUILD INTO AREA FOR THURSDAY. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE 00Z TAFS ARE FORECASTING MAINLY VFR CONDITIONS AT KILG WITH THE MOST PROLONGED IFR CONDITIONS AT KTTN. GENERICALLY SPEAKING BECAUSE OF THE SNOW NERN CWA AIRPORTS AND TERMINALS WILL BE IMPACTED THE GREATEST AND LONGEST WITH PROBABLY IFR CONDITIONS AND SOUTHWESTERN AIRPORTS AND TERMINALS THE LEAST. FOR TONIGHT EXPECT CONDITIONS TO DROP DOWN TO AT LEAST MVFR (BOTH CIGS AND VSBYS) AS PCPN CONTINUES TO WRAPAROUND. MOST OF THESE LOWER CONDITIONS SHOULD OCCUR AFTER 05Z. THERE COULD BE SOME RAIN MIXED IN WITH THE PRECIPITATION AROUND THE KPHL METRO AIRPORTS, BUT THE TREND WILL BE TOWARD SNOW AND THE CHANCES INCREASE AS THE NIGHT PROGRESSES. WE DID NOT CARRY ANY WIND GUSTS, A STEADY NORTH WIND AT 10 TO 15 KNOTS. ON FRIDAY MORNING SNOW OR SNOW SHOWERS (OR CHANCES) SHOULD BE SLOWLY ENDING FROM KILG AND KRDG EASTWARD. MVFR TO IFR CONDITIONS (MAINLY DUE TO VSBY) SHOULD BE IMPROVING TO VFR AS THE MORNING PROGRESSES. SNOW CHANCES AT KACY MIGHT LIGHTER INTO THE EARLY AFTERNOON. THE NORTH TO NORTHWEST WINDS SHOULD BECOME BLUSTERY AGAIN WITH PEAK GUSTS AT AROUND 30 KNOTS. CIGS WILL BE VFR, BUT WE ARE NOT EXPECTING TO LOSE THEM UNTIL FRIDAY NIGHT. OUTLOOK... FRIDAY NIGHT...MAINLY VFR CONDITIONS EXPECTED. NORTHERLY WINDS AROUND 10 TO 15 KNOTS WITH GUSTS UP TO 20 KNOTS, DIMINISHING SOME OVERNIGHT. SATURDAY AND SUNDAY...VFR CONDITIONS EXPECTED. NORTH TO NORTHEAST WINDS AROUND 10 KNOTS ON SATURDAY, DIMINISHING OVERNIGHT. WINDS BECOME SOUTH TO SOUTHEAST ON SUNDAY, AROUND 5 TO 10 KNOTS. INCREASING CLOUDINESS, ESPECIALLY SUNDAY NIGHT, BUT VFR CONDITIONS EXPECTED TO CONTINUE. MONDAY...MAINLY VFR CONDITIONS EXPECTED. WINDS WILL BE SOUTHERLY AROUND 10 KNOTS. MONDAY NIGHT THROUGH TUESDAY...VFR CONDITIONS WILL DETERIORATE TO MVFR, POSSIBLY IFR, WITH RAIN. SOUTH WINDS WILL LIGHTEN OVERNIGHT BEFORE BECOMING WESTERLY ON TUESDAY. CONDITIONS WILL BEGIN TO IMPROVE THROUGH THE DAY ON TUESDAY. && .MARINE... GALES HAD SUBSIDED OVER THE WATERS EARLY THIS AFTERNOON. ALTHOUGH THE SECONDARY SYSTEM IS EXPECTED TO CAUSE GALES TO DEVELOP AGAIN OVERNIGHT TONIGHT, WE CARVED OUT A PERIOD OF SUB-GALE FORCE WINDS IN THE FORECAST AND RECONFIGURED THE GALE WARNING TO START OVER OUR WATERS AFTER MIDNIGHT. WE RUN IT THROUGH FRIDAY OVER ALL WATERS. OUTLOOK... GALES WILL CONTINUE THROUGH 06Z/SAT (1AM SAT) ON THE OCEAN. LOW PRESSURE WILL CONTINUE TO PUSH EASTWARD FRIDAY NIGHT AS HIGH PRESSURE GRADUALLY BUILDS IN FROM THE WEST. THE GRADIENT BETWEEN THE TWO SYSTEMS WILL KEEP THE WINDS GUSTING TO GALE FORCE FRIDAY NIGHT. THE GRADIENT STARTS TO WEAKEN OVERNIGHT AND THE WINDS SHOULD DROP BELOW GALE FORCE BY AROUND MIDNIGHT OR SO ACROSS THE OCEAN. ONCE THE GALES COME DOWN, SMALL CRAFT ADVISORIES WILL BE NEEDED AS WINDS WILL REMAIN GUSTY THROUGH SATURDAY. THE HIGH PRESSURE SLIDES OVER THE REGION ON SUNDAY AND THEN MOVES OFFSHORE BY SUNDAY NIGHT. SEAS WILL REMAIN ABOVE 5 FEET THROUGH THE WEEKEND AND WILL MAINLY CONTINUE TO REMAIN NEAR OR ABOVE 5 FEET INTO EARLY NEXT WEEK. && .TIDES/COASTAL FLOODING... DECIDED TO CANCEL THE FLOOD WARNING FOR THE LOWER BAY AND OCEANFRONT BASED ON CURRENT AND PROJECTED DEPARTURES. A LOT OF THE GAUGES ON THE OCEANFRONT STRUGGLED TO REACH LOW-END MODERATE WITH THIS MORNINGS HIGH TIDE, WHICH WAS THE HIGHER OF THE TWO TODAY. WITH THIS LATEST HIGH TIDE WE BARELY REACHED MINOR TIDAL AS THE SURFACE WINDS BACKED MORE TOWARDS THE NORTHWEST AS THE CENTER OF THE LOW PRESSURE PULLS FURTHER TO THE NORTHEAST. CURRENTLY RUNNING AROUND A 2 FOOT DEPARTURE IN MOST PLACES AND IF THAT WERE TO REMAIN CONSISTENT THROUGH FRIDAY MORNINGS HIGH TIDE CYCLE WOULD YIELD WIDESPREAD MINOR TIDAL FLOODING. WE SHOULD CONTINUE TO HAVE MORE OF AN OFFSHORE FLOW TONIGHT AND TOMORROW MORNING WHICH WOULD KEEP DEPARTURES STEADY OR SLOWLY FALLING. THAT BEING SAID THE WARNING HAS BEEN REPLACED WITH AN ADVISORY. WE WILL CONTINUE TO MONITOR THE TIDES OVER THE SUBSEQUENT SHIFTS AND MAKE ADJUSTMENTS AS NEEDED. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR NJZ001-008. COASTAL FLOOD ADVISORY UNTIL 9 AM EST FRIDAY FOR NJZ012>014- 020>027. DE...COASTAL FLOOD ADVISORY UNTIL 9 AM EST FRIDAY FOR DEZ002>004. MD...NONE. MARINE...GALE WARNING FROM 1 AM FRIDAY TO 1 AM EST SATURDAY FOR ANZ450>455. GALE WARNING FROM 1 AM TO 6 PM EST FRIDAY FOR ANZ430-431. && $$ SYNOPSIS...MEOLA NEAR TERM...DELISI/GIGI SHORT TERM...DELISI LONG TERM...MEOLA AVIATION...GIGI/MEOLA MARINE...DELISI/MEOLA TIDES/COASTAL FLOODING...HEAVENER
AREA FORECAST DISCUSSION...UPDATE
NWS TAMPA BAY RUSKIN FL
545 AM EST WED MAR 6 2013 .UPDATE... LOW LEVEL FOCUS ALONG A FAST MOVING COLD FRONT HAS RESULTED IN MORE ORGANIZATION TO THE SHOWER ACTIVITY AS IT PROCEEDS SOUTH OF THE TAMPA BAY AREA. THE AREA OF SHOWERS IS STILL RATHER NARROW AND MOVING FAST...SO ANY PERIOD OF RAIN/SHOWERS WILL BE BRIEF EARLY THIS MORNING FOR THE SOUTHERN HALF OF THE AREA. HOWEVER...HAVE RAISED RAIN CHANCES TO LIKELY FOR THESE ZONES TO ACCOUNT FOR THE MORE SOLID BAND NOW SEEN ON REGIONAL RADAR. THIS BAND OF SHOWERS AND THE ASSOCIATED COLD FRONT WILL CONTINUE TO RAPIDLY PUSH SOUTH THE NEXT COUPLE OF HOURS AND BE SOUTH OF FT MYERS...AND OUT OF THE FORECAST AREA BY AROUND 10AM. && .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A FAIRLY AMPLIFIED UPPER LEVEL PATTERN ACROSS THE CONUS EARLY THIS MORNING. LARGE LONGWAVE RIDGING IS NOW IN PLACE ACROSS MUCH OF THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS WITH THE DOWNSTREAM FLOW DROPPING QUICKLY INTO A SHARP TROUGH OVER THE EASTERN STATES. THIS TROUGH IS ANCHORED BY A TIGHT/POTENT UPPER LEVEL LOW EXITING THE TN VALLEY TOWARD THE MID-ATLANTIC COAST. THIS ENERGY AND ASSOCIATED SURFACE FEATURE WILL BRING A SIGNIFICANT SNOWFALL TO PARTS OF THE MID-ATLANTIC THROUGH WEDNESDAY. OUR FORECAST AREA RESIDES AT THE BASE OF THIS TROUGH...FAR REMOVED FROM ANY SIGNIF MID/UPPER LEVEL SYNOPTIC/QG FORCING. WV IMAGERY SHOWS A NARROW BAND OF MOISTURE DROPPING SOUTH ACROSS THE PENINSULA FOLLOWED QUICKLY BY MARKED DRYING/SUBSIDENCE IN THE WAKE OF THE PASSING SHORTWAVE JUST TO OUR NORTH. THIS DRYING WILL OVERSPREAD OUR SKIES THROUGH THE DAY. THERE IS ALSO QUITE A SURGE OF COLD AIR ABOVE THE SURFACE ASSOCIATED WITH THIS SYSTEM TO OUR NORTH...HOWEVER THE MAIN SURGE OF THIS AIRMASS WILL BE TOWARD THE GA/CAROLINA COAST AND PREVENT THE ARRIVAL OF ANOTHER AIRMASS COMPARABLE TO WHAT WAS SEEN THIS PREVIOUS WEEKEND. AT THE SURFACE...WELL DEFINED COLD FRONT IS QUICKLY DROPPING TO THE SOUTHEAST INTO THE NORTH-CENTRAL FL PENINSULA. JUST ENOUGH MOISTURE IN THE LOW LEVELS AND FRONTAL FOCUS THIS MORNING TO SUPPORT A NARROW BAND OF BROKEN (MAINLY LIGHT) SHOWERS. WINDS PICK UP QUICKLY FROM THE NW IN THE WAKE OF THE FRONT...AND IT WILL LIKELY BE FAIRLY EVIDENT BY THIS SURGE OF WIND WHEN THE FRONT PASSES ANY GIVEN LOCATION THROUGH THE MORNING HOURS. && .SHORT TERM (TODAY THROUGH FRIDAY)... TODAY...COLD FRONT WILL QUICKLY DROP SOUTH THROUGH AND OUT OF THE FORECAST AREA THIS MORNING. CURRENT GRIDS SHOW THE FRONT PASSING SOUTH OF FT. MYERS BY LATE MORNING. THERE WILL BE A CHANCE OF A BRIEF SHOWER OR SPRINKLE AHEAD OF THIS FRONT TO THE SOUTH OF TAMPA BAY THROUGH MID MORNING...HOWEVER ANY RAINFALL WILL NOT AMOUNT TO MUCH. BY SUNRISE...THE FRONT LOOKS TO HAVE ALREADY PASSED TAMPA BAY AND POINTS NORTH TAKING ANY SCATTERED SHOWERS SOUTHWARD WITH IT. THEREFORE...FORECAST WILL SHOW SKIES CLEARING FROM NORTH TO SOUTH THROUGH THE DAY WITH MOST OF THE REGION SEEING ABUNDANT SUNSHINE BY EARLY AFTERNOON. EXPECTING A BREEZY/GUSTY DAY WITH NW WINDS BEHIND THE FRONT...AND A LAKE WIND ADVISORY HAS BEEN ISSUED FOR THIS MORNING THROUGH EARLY EVENING. THE MOST EVIDENT CAA WILL BE NORTH OF THE I-4 CORRIDOR WHERE HIGH TEMPS WILL HOLD IN THE LOW/MID 60S. SOUTH OF I-4 TEMPS WILL MAKE A RUN AT 70. COOLEST TEMPS WILL BE ALONG THE COAST FROM MANATEE COUNTY NORTHWARD WITH FLOW OFF THE RELATIVELY COOLER SHELF WATERS. THE STRONG NW WINDS WILL ALSO BRING BUILDING SWELL/SURF FOR AREA BEACHES AND WILL RESULT IN A MODERATE/ELEVATED RISK OF RIP CURRENTS FROM PINELLAS COUNTY SOUTHWARD. THIS ELEVATED RISK SHOULD LINGER INTO THURSDAY MORNING BEFORE THE SWELL AND ONSHORE WIND COMPONENT BEGINS TO DECLINE. TONIGHT...A CHILLY MARCH NIGHT IN STORE IN THE DRY POST-FRONTAL ENVIRONMENT. SOME OF THE STATISTICAL GUIDANCE IS SHOWING READINGS A COUPLE OF DEGREES BELOW FREEZING FOR THE INTERIOR NATURE COAST. HOWEVER...STATISTICAL GUIDANCE IS ALMOST ALWAYS AT LEAST SEVERAL DEGREES TOO COLD WITH ADVECTION SCENARIOS ON THE FIRST NIGHT BEHIND FRONTS. THERE IS NO DOUBT THAT IT WILL BE A COLD (MIDDLE/UPPER 30S COMMON AWAY FROM THE COAST...BUT AT THIS TIME WILL KEEP TEMPERATURES JUST ABOVE FREEZING...EVEN UP TOWARD CITRUS AND LEVY COUNTIES. ALSO SINCE THE GRADIENT WILL STAY UP AND OVERNIGHT DEWPOINT DEPRESSIONS ARE FORECAST TO BE 5-8 DEGREES...THE THREAT OF FROST APPEARS LOW. EACH OF THESE FACTORS WILL NEED TO BE RE-EVALUATED DURING THE DAY. THURSDAY/THURSDAY NIGHT... A BROAD DEEP LAYER NORTHWEST FLOW WILL BE IN PLACE ON THE BACKSIDE OF LONGWAVE TROUGHING OFF THE ATLANTIC SEABOARD. THIS FLOW WILL KEEP A STEADY SUPPLY OF DRY AIR ARRIVING FROM THE NORTH. MAY SEE A BOUT OF HIGHER CIRRUS LATER THURSDAY/THURSDAY EVENING OVER THE NORTHERN HALF OF THE STATE ASSOCIATED WITH A WEAK PASSING SHORTWAVE...BUT OTHERWISE SKIES LOOK TO BE MOSTLY CLEAR. WINDS WILL BE LESS GUSTY FOR THURSDAY AS SURFACE RIDGING CONTINUES TO BUILD IN FROM THE NORTHWEST. HIGH TEMPS WILL GENERALLY REACH THE UPPER 60S TO NEAR 70 NORTH AND THE LOWER/MID 70S SOUTH. BEACH TEMPS WILL LIKELY AGAIN BE HELD IN THE 60S WITH AT LEAST SOME ONSHORE FLOW COMPONENT... ESPECIALLY NORTH OF LEE/CHARLOTTE COUNTIES. WIDESPREAD 40S THURSDAY NIGHT FOR LOW TEMPS...WITH SOME UPPER 30S FOR THE NATURE COAST. FRIDAY... "CHAMBER OF COMMERCE" WEATHER TO END THE WORK WEEK AFTER A COOL EARLY MORNING START. STACKED RIDGING WILL BE BUILDING EASTWARD ACROSS THE GULF TOWARD THE AREA CONTINUING A FORECAST OF ABUNDANT SUNSHINE AND WARMING TEMPERATURES. && .LONG TERM (FRIDAY NIGHT THROUGH NEXT TUESDAY)... THE PERIOD BEGINS WITH DEEP LAYER RIDGING FROM THE GULF TO THE GREAT LAKES. THROUGH THE WEEKEND THIS RIDGING SLOWLY SHIFTS EAST ACROSS THE AREA WITH DRY AND SEASONABLE CONDITIONS AS WINDS VEER FROM NORTH TO SOUTHEAST AND MAY BE ROBUST AT TIMES ON THE GULF. BY MON THE RIDGING WILL BE EAST OF FL AS AN UPPER LOW/TROUGH WITH AN ATTENDANT SURFACE FRONT MOVES INTO THE MID CONUS. THIS SYSTEM CONTINUES EAST TUE...PUSHING THE FRONT DOWN THE STATE WITH INCREASING CLOUDS AND A SLIGHT CHANCE OF SHOWERS SPREADING SOUTHWARD. THE LATEST GFS AND ECMWF GUIDANCE WERE FAIRLY CONSISTENT THROUGH THE PERIOD BUT BEGIN TO DIVERGE TUE WITH THE ECMWF SLOWER THAN THE GFS IN MOVING THE FRONT ACROSS FL. && .AVIATION... APPROACHING FRONT WILL SPREAD SHRA/VCSH UNDER BKN MVFR CIGS SOUTHWARD...BEGINNING AT 09Z IN THE NORTH AND ENDING AROUND 18Z IN THE SOUTH. SOUTH AND SW WINDS SHIFT TO NW AND GUSTY FOR THE LATE MORNING AND AFTERNOON. && .MARINE... A COLD FRONT WILL QUICKLY PASS SOUTH THROUGH THE EASTERN GULF OF MEXICO THIS MORNING. WINDS FROM THE NORTHWEST AND SEAS WILL RAPIDLY INCREASE TO ADVISORY LEVELS BEHIND THE FRONT AND LINGER THROUGH THE DAY AND EVENING. LATER TONIGHT...WINDS AND SEAS WILL BEGIN TO SUBSIDE. WINDS AND SEAS WILL GENERALLY REMAIN BELOW HEADLINE CRITERIA FROM THURSDAY AFTERNOON THROUGH THE DAYLIGHT HOURS FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THIS RIDGE SLIDES EASTWARD FOR THE UPCOMING WEEKEND SETTING UP A GOOD SCENARIO FOR NOCTURNAL AND EARLY MORNING EASTERLY WIND SURGES. THESE SURGES ARE CURRENTLY FORECAST TO REACH CAUTIONARY LEVELS BOTH FRIDAY NIGHT AND SATURDAY NIGHT. && .FIRE WEATHER... DRY AIR ARRIVING BEHIND A COLD FRONT WILL COMBINE WITH GUSTY NW WINDS AND ERC VALUES ABOVE 27 TO RESULT IN RED FLAG CONDITIONS FOR MOST OF THE REGION THIS AFTERNOON. THE ONLY EXCEPTIONS WILL BE NEAR THE COAST WHERE ONSHORE FLOW SHOULD HELP PREVENT CRITICAL RELATIVE HUMIDITY LEVELS. SEVERAL HOURS OF CRITICALLY LOW RELATIVE HUMIDITY APPEAR LIKELY FOR THURSDAY LATE MORNING/AFTERNOON AS WELL. HOWEVER...LIGHTER WINDS AND CURRENT ERC VALUES BELOW 37 DO NOT MATCH RED FLAG CRITERIA FOR ANY ZONES. THIS POTENTIAL FOR RED FLAG CONDITIONS CAN BE RE-EVALUATED THIS AFTERNOON WITH THE ISSUANCE OF THE NEW ERC VALUES. IF ANY ZONES RISE TO 37 OR HIGHER...WARNINGS WILL LIKELY BECOME REQUIRED. && .PRELIMINARY POINT TEMPS/POPS... TPA 64 43 67 47 / 10 0 0 0 FMY 72 44 71 48 / 30 0 0 0 GIF 68 40 72 44 / 10 0 0 0 SRQ 65 44 67 46 / 20 0 0 0 BKV 64 36 68 38 / 10 0 0 0 SPG 63 49 67 53 / 10 0 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE- HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE- PASCO-PINELLAS-POLK-SARASOTA-SUMTER. RED FLAG WARNING FROM NOON TODAY TO 7 PM EST THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS- HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-POLK-SARASOTA- SUMTER. BEACH HAZARDS STATEMENT THROUGH THURSDAY MORNING FOR CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA. GULF WATERS...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR TARPON SPRINGS TO SUWANNEE RIVER OUT 20 NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM. SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR BONITA BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM- TAMPA BAY WATERS. && $$ UPDATE/SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS TAMPA BAY RUSKIN FL
300 AM EST WED MAR 6 2013 .SYNOPSIS... 08Z WATER VAPOR AND H4 RAP ANALYSIS SHOWING A FAIRLY AMPLIFIED UPPER LEVEL PATTERN ACROSS THE CONUS EARLY THIS MORNING. LARGE LONGWAVE RIDGING IS NOW IN PLACE ACROSS MUCH OF THE INTER-MOUNTAIN WEST AND CENTRAL PLAINS WITH THE DOWNSTREAM FLOW DROPPING QUICKLY INTO A SHARP TROUGH OVER THE EASTERN STATES. THIS TROUGH IS ANCHORED BY A TIGHT/POTENT UPPER LEVEL LOW EXITING THE TN VALLEY TOWARD THE MID-ATLANTIC COAST. THIS ENERGY AND ASSOCIATED SURFACE FEATURE WILL BRING A SIGNIFICANT SNOWFALL TO PARTS OF THE MID-ATLANTIC THROUGH WEDNESDAY. OUR FORECAST AREA RESIDES AT THE BASE OF THIS TROUGH...FAR REMOVED FROM ANY SIGNIF MID/UPPER LEVEL SYNOPTIC/QG FORCING. WV IMAGERY SHOWS A NARROW BAND OF MOISTURE DROPPING SOUTH ACROSS THE PENINSULA FOLLOWED QUICKLY BY MARKED DRYING/SUBSIDENCE IN THE WAKE OF THE PASSING SHORTWAVE JUST TO OUR NORTH. THIS DRYING WILL OVERSPREAD OUR SKIES THROUGH THE DAY. THERE IS ALSO QUITE A SURGE OF COLD AIR ABOVE THE SURFACE ASSOCIATED WITH THIS SYSTEM TO OUR NORTH...HOWEVER THE MAIN SURGE OF THIS AIRMASS WILL BE TOWARD THE GA/CAROLINA COAST AND PREVENT THE ARRIVAL OF ANOTHER AIRMASS COMPARABLE TO WHAT WAS SEEN THIS PREVIOUS WEEKEND. AT THE SURFACE...WELL DEFINED COLD FRONT IS QUICKLY DROPPING TO THE SOUTHEAST INTO THE NORTH-CENTRAL FL PENINSULA. JUST ENOUGH MOISTURE IN THE LOW LEVELS AND FRONTAL FOCUS THIS MORNING TO SUPPORT A NARROW BAND OF BROKEN (MAINLY LIGHT) SHOWERS. WINDS PICK UP QUICKLY FROM THE NW IN THE WAKE OF THE FRONT...AND IT WILL LIKELY BE FAIRLY EVIDENT BY THIS SURGE OF WIND WHEN THE FRONT PASSES ANY GIVEN LOCATION THROUGH THE MORNING HOURS. && .SHORT TERM (TODAY THROUGH FRIDAY)... TODAY...COLD FRONT WILL QUICKLY DROP SOUTH THROUGH AND OUT OF THE FORECAST AREA THIS MORNING. CURRENT GRIDS SHOW THE FRONT PASSING SOUTH OF FT. MYERS BY LATE MORNING. THERE WILL BE A CHANCE OF A BRIEF SHOWER OR SPRINKLE AHEAD OF THIS FRONT TO THE SOUTH OF TAMPA BAY THROUGH MID MORNING...HOWEVER ANY RAINFALL WILL NOT AMOUNT TO MUCH. BY SUNRISE...THE FRONT LOOKS TO HAVE ALREADY PASSED TAMPA BAY AND POINTS NORTH TAKING ANY SCATTERED SHOWERS SOUTHWARD WITH IT. THEREFORE...FORECAST WILL SHOW SKIES CLEARING FROM NORTH TO SOUTH THROUGH THE DAY WITH MOST OF THE REGION SEEING ABUNDANT SUNSHINE BY EARLY AFTERNOON. EXPECTING A BREEZY/GUSTY DAY WITH NW WINDS BEHIND THE FRONT...AND A LAKE WIND ADVISORY HAS BEEN ISSUED FOR THIS MORNING THROUGH EARLY EVENING. THE MOST EVIDENT CAA WILL BE NORTH OF THE I-4 CORRIDOR WHERE HIGH TEMPS WILL HOLD IN THE LOW/MID 60S. SOUTH OF I-4 TEMPS WILL MAKE A RUN AT 70. COOLEST TEMPS WILL BE ALONG THE COAST FROM MANATEE COUNTY NORTHWARD WITH FLOW OFF THE RELATIVELY COOLER SHELF WATERS. THE STRONG NW WINDS WILL ALSO BRING BUILDING SWELL/SURF FOR AREA BEACHES AND WILL RESULT IN A MODERATE/ELEVATED RISK OF RIP CURRENTS FROM PINELLAS COUNTY SOUTHWARD. THIS ELEVATED RISK SHOULD LINGER INTO THURSDAY MORNING BEFORE THE SWELL AND ONSHORE WIND COMPONENT BEGINS TO DECLINE. TONIGHT...A CHILLY MARCH NIGHT IN STORE IN THE DRY POST-FRONTAL ENVIRONMENT. SOME OF THE STATISTICAL GUIDANCE IS SHOWING READINGS A COUPLE OF DEGREES BELOW FREEZING FOR THE INTERIOR NATURE COAST. HOWEVER...STATISTICAL GUIDANCE IS ALMOST ALWAYS AT LEAST SEVERAL DEGREES TOO COLD WITH ADVECTION SCENARIOS ON THE FIRST NIGHT BEHIND FRONTS. THERE IS NO DOUBT THAT IT WILL BE A COLD (MIDDLE/UPPER 30S COMMON AWAY FROM THE COAST...BUT AT THIS TIME WILL KEEP TEMPERATURES JUST ABOVE FREEZING...EVEN UP TOWARD CITRUS AND LEVY COUNTIES. ALSO SINCE THE GRADIENT WILL STAY UP AND OVERNIGHT DEWPOINT DEPRESSIONS ARE FORECAST TO BE 5-8 DEGREES...THE THREAT OF FROST APPEARS LOW. EACH OF THESE FACTORS WILL NEED TO BE RE-EVALUATED DURING THE DAY. THURSDAY/THURSDAY NIGHT... A BROAD DEEP LAYER NORTHWEST FLOW WILL BE IN PLACE ON THE BACKSIDE OF LONGWAVE TROUGHING OFF THE ATLANTIC SEABOARD. THIS FLOW WILL KEEP A STEADY SUPPLY OF DRY AIR ARRIVING FROM THE NORTH. MAY SEE A BOUT OF HIGHER CIRRUS LATER THURSDAY/THURSDAY EVENING OVER THE NORTHERN HALF OF THE STATE ASSOCIATED WITH A WEAK PASSING SHORTWAVE...BUT OTHERWISE SKIES LOOK TO BE MOSTLY CLEAR. WINDS WILL BE LESS GUSTY FOR THURSDAY AS SURFACE RIDGING CONTINUES TO BUILD IN FROM THE NORTHWEST. HIGH TEMPS WILL GENERALLY REACH THE UPPER 60S TO NEAR 70 NORTH AND THE LOWER/MID 70S SOUTH. BEACH TEMPS WILL LIKELY AGAIN BE HELD IN THE 60S WITH AT LEAST SOME ONSHORE FLOW COMPONENT... ESPECIALLY NORTH OF LEE/CHARLOTTE COUNTIES. WIDESPREAD 40S THURSDAY NIGHT FOR LOW TEMPS...WITH SOME UPPER 30S FOR THE NATURE COAST. FRIDAY... "CHAMBER OF COMMERCE" WEATHER TO END THE WORK WEEK AFTER A COOL EARLY MORNING START. STACKED RIDGING WILL BE BUILDING EASTWARD ACROSS THE GULF TOWARD THE AREA CONTINUING A FORECAST OF ABUNDANT SUNSHINE AND WARMING TEMPERATURES. && .LONG TERM (FRIDAY NIGHT THROUGH NEXT TUESDAY)... THE PERIOD BEGINS WITH DEEP LAYER RIDGING FROM THE GULF TO THE GREAT LAKES. THROUGH THE WEEKEND THIS RIDGING SLOWLY SHIFTS EAST ACROSS THE AREA WITH DRY AND SEASONABLE CONDITIONS AS WINDS VEER FROM NORTH TO SOUTHEAST AND MAY BE ROBUST AT TIMES ON THE GULF. BY MON THE RIDGING WILL BE EAST OF FL AS AN UPPER LOW/TROUGH WITH AN ATTENDANT SURFACE FRONT MOVES INTO THE MID CONUS. THIS SYSTEM CONTINUES EAST TUE...PUSHING THE FRONT DOWN THE STATE WITH INCREASING CLOUDS AND A SLIGHT CHANCE OF SHOWERS SPREADING SOUTHWARD. THE LATEST GFS AND ECMWF GUIDANCE WERE FAIRLY CONSISTENT THROUGH THE PERIOD BUT BEGIN TO DIVERGE TUE WITH THE ECMWF SLOWER THAN THE GFS IN MOVING THE FRONT ACROSS FL. && .AVIATION... APPROACHING FRONT WILL SPREAD SHRA/VCSH UNDER BKN MVFR CIGS SOUTHWARD...BEGINNING AT 09Z IN THE NORTH AND ENDING AROUND 18Z IN THE SOUTH. SOUTH AND SW WINDS SHIFT TO NW AND GUSTY FOR THE LATE MORNING AND AFTERNOON. && .MARINE... A COLD FRONT WILL QUICKLY PASS SOUTH THROUGH THE EASTERN GULF OF MEXICO THIS MORNING. WINDS FROM THE NORTHWEST AND SEAS WILL RAPIDLY INCREASE TO ADVISORY LEVELS BEHIND THE FRONT AND LINGER THROUGH THE DAY AND EVENING. LATER TONIGHT...WINDS AND SEAS WILL BEGIN TO SUBSIDE. WINDS AND SEAS WILL GENERALLY REMAIN BELOW HEADLINE CRITERIA FROM THURSDAY AFTERNOON THROUGH THE DAYLIGHT HOURS FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE NORTH. THIS RIDGE SLIDES EASTWARD FOR THE UPCOMING WEEKEND SETTING UP A GOOD SCENARIO FOR NOCTURNAL AND EARLY MORNING EASTERLY WIND SURGES. THESE SURGES ARE CURRENTLY FORECAST TO REACH CAUTIONARY LEVELS BOTH FRIDAY NIGHT AND SATURDAY NIGHT. && .FIRE WEATHER... DRY AIR ARRIVING BEHIND A COLD FRONT WILL COMBINE WITH GUSTY NW WINDS AND ERC VALUES ABOVE 27 TO RESULT IN RED FLAG CONDITIONS FOR MOST OF THE REGION THIS AFTERNOON. THE ONLY EXCEPTIONS WILL BE NEAR THE COAST WHERE ONSHORE FLOW SHOULD HELP PREVENT CRITICAL RELATIVE HUMIDITY LEVELS. SEVERAL HOURS OF CRITICALLY LOW RELATIVE HUMIDITY APPEAR LIKELY FOR THURSDAY LATE MORNING/AFTERNOON AS WELL. HOWEVER...LIGHTER WINDS AND CURRENT ERC VALUES BELOW 37 DO NOT MATCH RED FLAG CRITERIA FOR ANY ZONES. THIS POTENTIAL FOR RED FLAG CONDITIONS CAN BE RE-EVALUATED THIS AFTERNOON WITH THE ISSUANCE OF THE NEW ERC VALUES. IF ANY ZONES RISE TO 37 OR HIGHER...WARNINGS WILL LIKELY BECOME REQUIRED. && .PRELIMINARY POINT TEMPS/POPS... TPA 64 43 67 47 / 10 0 0 0 FMY 72 44 71 48 / 30 0 0 0 GIF 68 40 72 44 / 10 0 0 0 SRQ 65 44 67 46 / 20 0 0 0 BKV 64 36 68 38 / 10 0 0 0 SPG 63 49 67 53 / 10 0 0 0 && .TBW WATCHES/WARNINGS/ADVISORIES... FL...LAKE WIND ADVISORY FROM 10 AM THIS MORNING TO 7 PM EST THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE- HERNANDO-HIGHLANDS-HILLSBOROUGH-LEE-LEVY-MANATEE- PASCO-PINELLAS-POLK-SARASOTA-SUMTER. RED FLAG WARNING FROM NOON TODAY TO 7 PM EST THIS EVENING FOR CHARLOTTE-CITRUS-DESOTO-HARDEE-HERNANDO-HIGHLANDS- HILLSBOROUGH-LEE-LEVY-MANATEE-PASCO-POLK-SARASOTA- SUMTER. BEACH HAZARDS STATEMENT THROUGH THURSDAY MORNING FOR CHARLOTTE-HILLSBOROUGH-LEE-MANATEE-PINELLAS-SARASOTA. GULF WATERS...SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR TARPON SPRINGS TO SUWANNEE RIVER OUT 20 NM-TARPON SPRINGS TO SUWANNEE RIVER OUT 20 TO 60 NM. SMALL CRAFT ADVISORY UNTIL 4 AM EST THURSDAY FOR BONITA BEACH TO ENGLEWOOD OUT 20 NM-BONITA BEACH TO ENGLEWOOD OUT 20 TO 60 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 NM-ENGLEWOOD TO TARPON SPRINGS OUT 20 TO 60 NM- TAMPA BAY WATERS. && $$ SYNOPSIS/SHORT TERM/MARINE/FIRE WX...MROCZKA LONG TERM/AVIATION...RUDE
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
249 PM EST WED MAR 6 2013 .UPDATE... THE LONG TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 350 AM EST WED MAR 6 2013 STRONG LOW PRESSURE OVER SOUTHEAST OHIO WILL MOVE ON TO THE EAST COAST AS UPPER DISTURBANCE MOVES SOUTHEAST ACROSS THE GREAT LAKES. OVER THE NEXT FEW DAYS MODELS MOVE AN AREA OF HIGH PRESSURE EAST INTO OUR REGION AND AN UPPER RIDGE OF HIGH PRESSURE OVER THE ROCKIES WILL MOVE OUR WAY BY SATURDAY. IN THE EXTENDED..AN AREA OF LOW PRESSURE WILL MOVE OUR WAY LATE SUNDAY AND MONDAY. TEMPERATURES WILL BE QUITE MILD THIS WEEKEND...BUT WILL COOL OFF SOME MONDAY AND TUESDAY AFTER A COLD FRONT MOVES THROUGH. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1006 AM EST WED MAR 6 2013 RADAR LOOP SHOWED SNOW SHOWERS HAD MOVED OUT OF THE AREA EARLIER THIS MORNING SO WINTER WEATHER ADVISORY WAS ALLOWED TO EXPIRE AT 9 AM. SATELLITE PICTURE SHOWS CLOUDY SKIES ACROSS ALL OF CENTRAL INDIANA AND THIS TREND SHOULD CONTINUE THROUGH THE DAY...WITH PERHAPS MOSTLY CLOUDY BY LATE THIS EVENING. WING GUSTS OF 20 TO 30 MPH CONTINUE ACROSS THE AREA BUT SHOULD LESSEN GRADUALLY THROUGHOUT THE DAY. FORECAST SOUNDINGS IN BOTH THE NAM AND THE RAP FOR THIS AFTERNOON SHOW SOME SHALLOW INSTABILITY AND RECENTLY THIS HAS BEEN A PRETTY GOOD INDICATOR OF LIGHT SNOW SHOWER DEVELOPMENT. WITH LITTLE IN THE WAY OF FORCING ON THE BACK SIDE OF THIS LOW HAVE OPTED AGAINST ADDING ANYTHING MEASURABLE BUT HAVE ADDED A CHANCE FOR FLURRIES FOR THE AFTERNOON. GOING HIGH TEMPERATURES IN THE 30S LOOK GOOD WITH THE CLOUD COVER AND NORTHWEST FLOW. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... ISSUED AT 350 AM EST WED MAR 6 2013 FORECAST FOCUS WILL BE ON SKY COVER AND TEMPERATURES AS MUCH QUIETER WEATHER WILL BE THE RULE. HIGH PRESSURE RIDGE DRIFTS ACROSS THE PLAINS WILL BUILD EAST ACROSS OUR REGION FRIDAY. WITH SUBSIDENCE...CLOUDS WILL GRADUALLY DECREASE LATER TONIGHT AND THURSDAY. MODELS MOVE AN UPPER DISTURBANCE ACROSS SOUTHEAST ACROSS THE EASTERN GREAT LAKES AND EASTERN OHIO LATER TONIGHT AND THURSDAY. WILL KEEP MORE CLOUDS ACROSS OUR NORTH AND EAST THROUGH THURSDAY. OTHERWISE...MOST AREAS WILL BECOME MOSTLY CLEAR THURSDAY NIGHT AND REMAIN THAT WAY UNTIL SATURDAY MORNING. WILL LEAN TOWARDS THE COOLER END OF MOS TEMPERATURES THROUGH THURSDAY NIGHT AS THERE WILL BE SOME SNOW COVER ESPECIALLY EAST. WITH CLEAR SKIES AND LIGHT WINDS WILL UNDERCUT MOS TEMPERATURES 4 TO 6 DEGREES THURSDAY NIGHT. BY FRIDAY THE SNOW COVER SHOULD BE MOSTLY GONE AND WILL WITH THE POSSIBLE EXCEPTION OUR FAR EAST. WILL GO CLOSE TO A MOS BLEND ON TEMPERATURES. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... ISSUED AT 249 PM EST WED MAR 6 2013 ACTIVE PATTERN RETURNS THROUGH THE PERIOD. AN UPPER LEVEL TROUGH WILL EJECT OUT OF THE ROCKIES SATURDAY NIGHT AND INDUCE A SURFACE LOW THAT WILL TRACK ACROSS THE CENTRAL PLAINS ON SUNDAY. EXTENDED MODEL GUIDANCE IN DECENT AGREEMENT ON KEEPING THE UPPER LEVEL WAVE FAIRLY PROGRESSIVE AS RIDGING ALOFT AHEAD OF THE SYSTEM BREAKS DOWN BY EARLY MONDAY. NICE SURGE OF WARM GULF AIR AHEAD OF THE SYSTEM WILL TRANSPORT PLENTY OF MOISTURE INTO THE OHIO VALLEY WITH PRECIP WATER VALUES CLIMBING TO AN INCH OR BETTER BY SUNDAY NIGHT AND MONDAY. ANY LINGERING PILES OF SNOW THAT STILL REMAIN BY THE WEEKEND WILL LIKELY BE WIPED OUT AS EXPECT WIDESPREAD RAINFALL TO ACCOMPANY THE LOW PRESSURE AND FRONTAL BOUNDARY. WILL CARRY LIKELY POPS SUNDAY NIGHT AND MONDAY AS THE LOW PASSES THROUGH THE OHIO VALLEY. HIGHS MAINLY IN THE 50S SUNDAY AND UPPER 40S/LOWER 50S MONDAY WILL FALL BACK INTO THE 40S FOR TUESDAY AND WEDNESDAY AS COLDER AIR RETURNS IN THE WAKE OF THE FRONTAL PASSAGE. COLDEST TEMPERATURES THROUGHOUT THE EXTENDED LIKELY TO BE WEDNESDAY AS AN UPPER LEVEL TROUGH CARVES OUT ACROSS THE GREAT LAKES. MAY SEE LIGHT SNOW MIX IN WITH RAIN AS PRECIP DIMINISHES MONDAY NIGHT INTO TUESDAY...WITH DRIER WEATHER RESUMING FOR MIDWEEK. && .AVIATION /DISCUSSION FOR 061800Z TAF ISSUANCE/... ISSUED AT 1222 PM EST WED MAR 6 2013 MVFR CEILINGS TO PERSIST THROUGHOUT THE FORECAST PERIOD. CENTRAL INDIANA REMAINS IN A COLD CYCLONIC FLOW IN THE WAKE OF THE STORM THAT IMPACTED THE REGION LAST NIGHT AND EARLY THIS MORNING. EXTENSIVE STRATUS DECK ENCOMPASSING THE GREAT LAKES AND OHIO VALLEY...WITH CEILINGS GENERALLY BETWEEN 1000-1500FT. EXPECT THICK STRATUS DECK TO REMAIN FOR THE REST OF THE DAY AND OVERNIGHT... POSSIBLY LIFTING TOWARDS 2000FT THROUGH THIS EVENING BEFORE FALLING BACK TONIGHT WITH THE INVERSION HOLDING. VERY WEAK SHALLOW INSTABILITY PRESENT THROUGH THE AFTERNOON COULD GENERATE A FEW FLURRIES WITH NO IMPACT TO TERMINALS. NORTHWEST WINDS AT 10-15KTS THIS AFTERNOON WILL DIMINISH TO AROUND 5KTS TONIGHT. INCREASINGLY DRIER AIR BUILDING INTO THE REGION THURSDAY WITH HIGH PRESSURE...BUT MODEL SOUNDINGS INDICATING LOWER CLOUDS WILL LIKELY BE SLOW TO BUDGE. WILL RAISE CEILINGS TO 2KFT THURSDAY MORNING WITH MORE SUBSTANTIAL CLEARING LIKELY TO HOLD OFF UNTIL LATER ON THURSDAY. LIGHT NORTHERLY FLOW IS EXPECTED THURSDAY. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...JH NEAR TERM...CP SHORT TERM...JH LONG TERM....RYAN AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1222 PM EST WED MAR 6 2013 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 350 AM EST WED MAR 6 2013 STRONG LOW PRESSURE OVER SOUTHEAST OHIO WILL MOVE ON TO THE EAST COAST AS UPPER DISTURBANCE MOVES SOUTHEAST ACROSS THE GREAT LAKES. OVER THE NEXT FEW DAYS MODELS MOVE AN AREA OF HIGH PRESSURE EAST INTO OUR REGION AND AN UPPER RIDGE OF HIGH PRESSURE OVER THE ROCKIES WILL MOVE OUR WAY BY SATURDAY. IN THE EXTENDED..AN AREA OF LOW PRESSURE WILL MOVE OUR WAY LATE SUNDAY AND MONDAY. TEMPERATURES WILL BE QUITE MILD THIS WEEKEND...BUT WILL COOL OFF SOME MONDAY AND TUESDAY AFTER A COLD FRONT MOVES THROUGH. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1006 AM EST WED MAR 6 2013 RADAR LOOP SHOWED SNOW SHOWERS HAD MOVED OUT OF THE AREA EARLIER THIS MORNING SO WINTER WEATHER ADVISORY WAS ALLOWED TO EXPIRE AT 9 AM. SATELLITE PICTURE SHOWS CLOUDY SKIES ACROSS ALL OF CENTRAL INDIANA AND THIS TREND SHOULD CONTINUE THROUGH THE DAY...WITH PERHAPS MOSTLY CLOUDY BY LATE THIS EVENING. WING GUSTS OF 20 TO 30 MPH CONTINUE ACROSS THE AREA BUT SHOULD LESSEN GRADUALLY THROUGHOUT THE DAY. FORECAST SOUNDINGS IN BOTH THE NAM AND THE RAP FOR THIS AFTERNOON SHOW SOME SHALLOW INSTABILITY AND RECENTLY THIS HAS BEEN A PRETTY GOOD INDICATOR OF LIGHT SNOW SHOWER DEVELOPMENT. WITH LITTLE IN THE WAY OF FORCING ON THE BACK SIDE OF THIS LOW HAVE OPTED AGAINST ADDING ANYTHING MEASURABLE BUT HAVE ADDED A CHANCE FOR FLURRIES FOR THE AFTERNOON. GOING HIGH TEMPERATURES IN THE 30S LOOK GOOD WITH THE CLOUD COVER AND NORTHWEST FLOW. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... ISSUED AT 350 AM EST WED MAR 6 2013 FORECAST FOCUS WILL BE ON SKY COVER AND TEMPERATURES AS MUCH QUIETER WEATHER WILL BE THE RULE. HIGH PRESSURE RIDGE DRIFTS ACROSS THE PLAINS WILL BUILD EAST ACROSS OUR REGION FRIDAY. WITH SUBSIDENCE...CLOUDS WILL GRADUALLY DECREASE LATER TONIGHT AND THURSDAY. MODELS MOVE AN UPPER DISTURBANCE ACROSS SOUTHEAST ACROSS THE EASTERN GREAT LAKES AND EASTERN OHIO LATER TONIGHT AND THURSDAY. WILL KEEP MORE CLOUDS ACROSS OUR NORTH AND EAST THROUGH THURSDAY. OTHERWISE...MOST AREAS WILL BECOME MOSTLY CLEAR THURSDAY NIGHT AND REMAIN THAT WAY UNTIL SATURDAY MORNING. WILL LEAN TOWARDS THE COOLER END OF MOS TEMPERATURES THROUGH THURSDAY NIGHT AS THERE WILL BE SOME SNOW COVER ESPECIALLY EAST. WITH CLEAR SKIES AND LIGHT WINDS WILL UNDERCUT MOS TEMPERATURES 4 TO 6 DEGREES THURSDAY NIGHT. BY FRIDAY THE SNOW COVER SHOULD BE MOSTLY GONE AND WILL WITH THE POSSIBLE EXCEPTION OUR FAR EAST. WILL GO CLOSE TO A MOS BLEND ON TEMPERATURES. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 336 PM EST TUE MAR 5 2013 AN UPPER RIDGE WILL BUILD OVER THE REGION LATE IN THE WORK WEEK AND MOVES EAST CROSS THE REGION THROUGH THE WEEKEND. DRY WEATHER AND WARMER TEMPERATURES WILL ENSUE ACROSS THE AREA. BY SUNDAY A BROAD UPPER TROUGH WILL APPROACH THE REGION. A DISTURBANCE OUT OF AHEAD OF THIS SYSTEM WILL MOVE ACROSS THE AREA SUNDAY...WITH THE STRONG UPPER LOW TO CROSS THE REGION MONDAY AND TUESDAY. SLIGHT CHANCE FOR RAIN WILL BE IN THE FORECAST FOR SUNDAY WITH HIGHER CHANCES FROM MONDAY INTO TUESDAY AS THE CENTER OF THE UPPER LOW MOVES ACROSS THE GREAT LAKES. ALL BLEND TEMPERATURES SEEM REASONABLE GIVEN MODEL CONSENSUS AND DID NOT MAKE ANY SIGNIFICANT CHANGES TO THEIR NUMBERS. && .AVIATION /DISCUSSION FOR 061800Z TAF ISSUANCE/... ISSUED AT 1222 PM EST WED MAR 6 2013 MVFR CEILINGS TO PERSIST THROUGHOUT THE FORECAST PERIOD. CENTRAL INDIANA REMAINS IN A COLD CYCLONIC FLOW IN THE WAKE OF THE STORM THAT IMPACTED THE REGION LAST NIGHT AND EARLY THIS MORNING. EXTENSIVE STRATUS DECK ENCOMPASSING THE GREAT LAKES AND OHIO VALLEY...WITH CEILINGS GENERALLY BETWEEN 1000-1500FT. EXPECT THICK STRATUS DECK TO REMAIN FOR THE REST OF THE DAY AND OVERNIGHT... POSSIBLY LIFTING TOWARDS 2000FT THROUGH THIS EVENING BEFORE FALLING BACK TONIGHT WITH THE INVERSION HOLDING. VERY WEAK SHALLOW INSTABILITY PRESENT THROUGH THE AFTERNOON COULD GENERATE A FEW FLURRIES WITH NO IMPACT TO TERMINALS. NORTHWEST WINDS AT 10-15KTS THIS AFTERNOON WILL DIMINISH TO AROUND 5KTS TONIGHT. INCREASINGLY DRIER AIR BUILDING INTO THE REGION THURSDAY WITH HIGH PRESSURE...BUT MODEL SOUNDINGS INDICATING LOWER CLOUDS WILL LIKELY BE SLOW TO BUDGE. WILL RAISE CEILINGS TO 2KFT THURSDAY MORNING WITH MORE SUBSTANTIAL CLEARING LIKELY TO HOLD OFF UNTIL LATER ON THURSDAY. LIGHT NORTHERLY FLOW IS EXPECTED THURSDAY. && .IND WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS...JH NEAR TERM...CP SHORT TERM...JH LONG TERM....NIELD AVIATION...RYAN
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1006 AM EST WED MAR 6 2013 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS... ISSUED AT 350 AM EST WED MAR 6 2013 STRONG LOW PRESSURE OVER SOUTHEAST OHIO WILL MOVE ON TO THE EAST COAST AS UPPER DISTURBANCE MOVES SOUTHEAST ACROSS THE GREAT LAKES. OVER THE NEXT FEW DAYS MODELS MOVE AN AREA OF HIGH PRESSURE EAST INTO OUR REGION AND AN UPPER RIDGE OF HIGH PRESSURE OVER THE ROCKIES WILL MOVE OUR WAY BY SATURDAY. IN THE EXTENDED..AN AREA OF LOW PRESSURE WILL MOVE OUR WAY LATE SUNDAY AND MONDAY. TEMPERATURES WILL BE QUITE MILD THIS WEEKEND...BUT WILL COOL OFF SOME MONDAY AND TUESDAY AFTER A COLD FRONT MOVES THROUGH. && .NEAR TERM /REST OF TODAY/... ISSUED AT 1006 AM EST WED MAR 6 2013 RADAR LOOP SHOWED SNOW SHOWERS HAD MOVED OUT OF THE AREA EARLIER THIS MORNING SO WINTER WEATHER ADVISORY WAS ALLOWED TO EXPIRE AT 9 AM. SATELLITE PICTURE SHOWS CLOUDY SKIES ACROSS ALL OF CENTRAL INDIANA AND THIS TREND SHOULD CONTINUE THROUGH THE DAY...WITH PERHAPS MOSTLY CLOUDY BY LATE THIS EVENING. WING GUSTS OF 20 TO 30 MPH CONTINUE ACROSS THE AREA BUT SHOULD LESSEN GRADUALLY THROUGHOUT THE DAY. FORECAST SOUNDINGS IN BOTH THE NAM AND THE RAP FOR THIS AFTERNOON SHOW SOME SHALLOW INSTABILITY AND RECENTLY THIS HAS BEEN A PRETTY GOOD INDICATOR OF LIGHT SNOW SHOWER DEVELOPMENT. WITH LITTLE IN THE WAY OF FORCING ON THE BACK SIDE OF THIS LOW HAVE OPTED AGAINST ADDING ANYTHING MEASURABLE BUT HAVE ADDED A CHANCE FOR FLURRIES FOR THE AFTERNOON. GOING HIGH TEMPERATURES IN THE 30S LOOK GOOD WITH THE CLOUD COVER AND NORTHWEST FLOW. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... ISSUED AT 350 AM EST WED MAR 6 2013 FORECAST FOCUS WILL BE ON SKY COVER AND TEMPERATURES AS MUCH QUIETER WEATHER WILL BE THE RULE. HIGH PRESSURE RIDGE DRIFTS ACROSS THE PLAINS WILL BUILD EAST ACROSS OUR REGION FRIDAY. WITH SUBSIDENCE...CLOUDS WILL GRADUALLY DECREASE LATER TONIGHT AND THURSDAY. MODELS MOVE AN UPPER DISTURBANCE ACROSS SOUTHEAST ACROSS THE EASTERN GREAT LAKES AND EASTERN OHIO LATER TONIGHT AND THURSDAY. WILL KEEP MORE CLOUDS ACROSS OUR NORTH AND EAST THROUGH THURSDAY. OTHERWISE...MOST AREAS WILL BECOME MOSTLY CLEAR THURSDAY NIGHT AND REMAIN THAT WAY UNTIL SATURDAY MORNING. WILL LEAN TOWARDS THE COOLER END OF MOS TEMPERATURES THROUGH THURSDAY NIGHT AS THERE WILL BE SOME SNOW COVER ESPECIALLY EAST. WITH CLEAR SKIES AND LIGHT WINDS WILL UNDERCUT MOS TEMPERATURES 4 TO 6 DEGREES THURSDAY NIGHT. BY FRIDAY THE SNOW COVER SHOULD BE MOSTLY GONE AND WILL WITH THE POSSIBLE EXCEPTION OUR FAR EAST. WILL GO CLOSE TO A MOS BLEND ON TEMPERATURES. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ISSUED AT 336 PM EST TUE MAR 5 2013 AN UPPER RIDGE WILL BUILD OVER THE REGION LATE IN THE WORK WEEK AND MOVES EAST CROSS THE REGION THROUGH THE WEEKEND. DRY WEATHER AND WARMER TEMPERATURES WILL ENSUE ACROSS THE AREA. BY SUNDAY A BROAD UPPER TROUGH WILL APPROACH THE REGION. A DISTURBANCE OUT OF AHEAD OF THIS SYSTEM WILL MOVE ACROSS THE AREA SUNDAY...WITH THE STRONG UPPER LOW TO CROSS THE REGION MONDAY AND TUESDAY. SLIGHT CHANCE FOR RAIN WILL BE IN THE FORECAST FOR SUNDAY WITH HIGHER CHANCES FROM MONDAY INTO TUESDAY AS THE CENTER OF THE UPPER LOW MOVES ACROSS THE GREAT LAKES. ALL BLEND TEMPERATURES SEEM REASONABLE GIVEN MODEL CONSENSUS AND DID NOT MAKE ANY SIGNIFICANT CHANGES TO THEIR NUMBERS. && .AVIATION /DISCUSSION FOR THE 061500Z TAF UPDATE/... ISSUED AT 947 AM EST WED MAR 6 2013 THICK MVFR STRATUS REMAINS ACROSS THE REGION THIS MORNING. MADE SOME MINOR ADJUSTMENTS TO CEILINGS BASED ON CURRENT OBS BUT IN GENERAL...12Z FORECAST LOOKS GOOD. GUSTS LIKELY TO CONTINUE AT KBMG...KIND AND POSSIBLY KHUF THROUGH THE REMAINDER OF THE MORNING. CANNOT RULE OUT A FEW FLURRIES INTO THE AFTERNOON...BUT ANY IMPACT TO TERMINALS WILL BE MINIMAL AT BEST AND WILL NOT INTRODUCE INTO FORECASTS AT THIS TIME. 12Z DISCUSSION FOLLOWS. MVFR CONDITIONS LIKELY THROUGH THE PERIOD IN THE WAKE OF DEPARTING LOW PRESSURE. SAVE FOR HUF...ALL SITES ARE NOW MVFR AND SNOW IS RAPIDLY COMING TO AN END...ASIDE FROM A FEW FLURRIES REMAINING. APPEARS LIKELY THAT MOISTURE WILL REMAIN TRAPPED UNDER A LOW LEVEL INVERSION THROUGH MUCH OF THE PERIOD...AND UPSTREAM OBSERVATIONS AND SATELLITE BEAR THIS OUT...SHOWING EXPANSIVE LOW CLOUD TO OUR WEST AND NORTHWEST. WINDS WILL GENERALLY REMAIN NORTHWESTERLY...WITH SOME GUSTS LIKELY EARLY IN THE PERIOD BEFORE THE SURFACE PRESSURE GRADIENT RELAXES. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JH NEAR TERM...CP SHORT TERM...JH LONG TERM....NIELD AVIATION...NIELD/RYAN
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
340 PM CST WED MAR 6 2013 .SYNOPSIS... ISSUED AT 332 PM CST WED MAR 6 2013 12Z UA ANALYSIS HAS A STRONG EXTRATROPICAL CYCLONE OVER THE MID ATLANTIC STATES WITH A RIDGE OVER THE PLAINS. SATELLITE TRENDS THROUGH MID AFTERNOON SHOW GRADUAL CLEARING AS THE STRONGER MARCH ALLOWS BREAKS TO DEVELOP IN THE MOISTURE LAYER TRAPPED UNDER THE INVERSION. 18Z SFC ANALYSIS HAS A RIDGE THROUGH THE PLAINS WITH AN INVERTED TROF RUNNING FROM THE OHIO VALLEY INTO UPPER MICHIGAN. DEW POINTS WERE IN THE TEENS AND 20S ACROSS THE MIDWEST. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 332 PM CST WED MAR 6 2013 NOT ONE MODEL IS HANDLING THE THIN MOISTURE LAYER TRAPPED UNDER THE INVERSION. THE RAP 0.5 KM RH/CONDENSATION PRESSURE/WIND HAS A LOOSE CORRELATION ON WHAT IS CURRENTLY HAPPENING. TAKING INPUTS FROM THE RAP TRENDS AND COMBINING THEM WITH SATELLITE TRENDS INDICATES CLEARING WILL OCCUR ACROSS THE WESTERN THIRD OF THE CWFA LATE THIS AFTERNOON WITH IT PROGRESSING EAST TO THE MISSISSIPPI BY SUNSET. AFTER SUNSET THE QUESTION THEN BECOMES WILL THE CLEARING TREND CONTINUE OR STOP. THE RAP SUGGESTS THE CLEARING WOULD STOP WITH CLOUDS REMAINING TRAPPED UNDER THE INVERSION. OTHER DATA SUGGEST THE CLEARING TREND WOULD CONTINUE BUT SLOW DOWN. SO...HAVE OPTED TO GO WITH THE IDEA OF SLOWING DOWN THE CLEARING TREND THIS EVENING WITH THE FAR EAST CLEARING AFTER MIDNIGHT. MOISTURE IN THE LOW LEVELS IS NOT REALLY BEING SCOURED OUT SO THOSE AREAS THAT CLEAR BY SUNSET WILL HAVE A FOG THREAT AS THE HIGH SETTLES ACROSS THE AREA. GOING ON THE ASSUMPTION THAT FOG WILL DEVELOP IN THE CLEAR SKIES AND LIGHT WINDS OVER THE SNOW PACK...AREAS ROUGHLY ALONG AND WEST OF THE MISSISSIPPI WOULD BE MOST AT RISK STARTING TOWARD MIDNIGHT AND CONTINUING INTO THURSDAY MORNING. THE EASTERN 40 PERCENT OF THE CWFA MAY SEE SOME PATCHY FOG DEVELOP AROUND SUNRISE. VERY LITTLE FOG DEVELOPED UNDER THE SFC RIDGE LAST NIGHT DUE TO CLOUD COVER. SO IT IS NOT KNOWN IF HEADLINES WOULD BE NEEDED FOR ANY FOG THAT DEVELOPS TONIGHT. TRENDS WILL NEED TO BE MONITORED DURING THE EVENING FOR THIS POSSIBLE THREAT. IF FOG DEVELOPS TONIGHT AND BECOMES SUFFICIENTLY THICK...THEN RIME DEPOSITS COULD DEVELOP ON SOME ROADS AND POSSIBLY RESULT IN SLICK SPOTS DEVELOPING. THURSDAY LOOKS TO BE QUIET AND DRY WITH SUNSHINE AS THE HIGH SLOWLY MOVES TOWARD MICHIGAN AND INDIANA. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 332 PM CST WED MAR 6 2013 MAIN FOCUS WITH STORM SYSTEM OVER THE WEEKEND INTO VERY EARLY NEXT WEEK AND PCPN CHCS/TYPE/AMOUNTS. LARGE CUTOFF LOW CHURNING JUST OFF THE PACIFIC NORTHWEST COAST EARLY THIS AFTERNOON IS SHOWN BY MODELS TO DIG INTO THE SOUTHWESTERN CONUS BY LATE WEEK BEFORE EJECTING OUT FROM THE ROCKIES THROUGH THE MID-MISSISSIPPI VALLEY OVER THE WEEKEND INTO EARLY NEXT WEEK. MODELS GENERALLY SHOW THE LOW OPENING UP AND EJECTING OUT AS POSITIVE TILTED TROUGH AS SUGGESTION OF SOME PHASING WITH CANADIAN PLAINS SHORTWAVE ENERGY. THE UNCERTAINTIES MOSTLY PERTAIN TO THE TRACK...AND ALSO STRENGTH/TIMING OF SYSTEM WEAKENING OR OPENING UP BOTH OF WHICH LIKELY IMPACTED BY THE AMOUNT OF INTERACTION WITH CANADIAN ENERGY. THE UNCERTAINTIES WITH TRACK AND STRENGTH OF SYSTEM TO HAVE IMPACT ON TEMPS AND PRECIPITATION TYPE AND AMOUNTS...AND WHETHER OR NOT WILL SEE A DEFORMATION ZONE. THIS WILL PROBABLY TO TAKE AT LEAST ANOTHER 24+ HRS TO RESOLVE AS THE CANADIAN ENERGY MOSTLY IN QUESTION IS STILL WELL OUT IN THE PACIFIC JUST SOUTH OF THE ALEUTIAN ISLANDS. THU NGT-FRIDAY NGT... MAINLY DRY AS HIGH PRESSURE IN CONTROL FOR MUCH OF THE PERIOD. FAVORED NEAR THE COLD SIDE OF GUIDANCE OR JUST BELOW ON TEMPS AS PAST EXPERIENCE WITH DRY LOW LEVEL E/SE FLOW ON BACKSIDE OF DEPARTING HIGH NOT CONDUCIVE FOR A LOT OF WARMING... ESPECIALLY WITH SNOW COVER. LOW LEVEL JET AND ATTENDANT STRONG MOISTURE TRANSPORT TO FUEL DEVELOPMENT OF PCPN TO OUR WEST BY FRIDAY EVENING AND MAY SEE SOME STRATIFYING LIGHT PCPN MOVE INTO WESTERN SECTIONS LATE FRIDAY NGT WITH VEERING/WEAKENING LOW LEVEL JET WELL NORTH OF DEVELOPING SFC WARM FRONT. COLD DRY FETCH FROM DEPARTING HIGH AND EVAPORATIONAL COOLING SUPPORT RISK OF SOME FREEZING RAIN WITH INITIAL ONSET OF PCPN BEFORE SATURATION AND CONTINUED WARM... MOIST ADVECTION ABATES RISK SATURDAY AM. SAT-SUN... RAIN EXPECTED TO EVENTUALLY OVERSPREAD CWA SAT-SAT NGT AND LINGER THROUGH SUNDAY WITH STRONG MOISTURE TRANSPORT AND INCREASINGLY DIFFLUENT FLOW ALOFT. SFC DEWPTS WELL INTO THE 40S AND 850 MB DEWPTS OF 5-7C COMBINED WITH MAGNITUDE OF FORCING SUPPORTIVE OF WIDESPREAD MODERATE TO HEAVY RAIN AMOUNTS 0.25 TO 1 INCH... WITH LOCALLY HIGHER AMOUNTS 1-2 INCHES WITH SOME CONVECTION. THIS RAISES CONCERNS ON FLOODING WITH POTENTIAL FOR RAPID SNOWMELT OCCURRING ALONGSIDE THE MODERATE TO HEAVY RAINS GIVEN AREA STREAMS AND RIVERS NEAR TO ABOVE NORMAL IN MANY LOCATIONS... WHILE FROST DEPTH DOWN TO 8 INCHES ALTHOUGH SOME THAW IN TOP PORTIONS BUT SATURATED... OVERALL SUPPORTIVE OF RUN-OFF INCREASING RISK FOR SOME LOW END FLOODING. CONTINUED TO UNCERCUT GUIDANCE ON TEMPS SAT AND EXPECT READINGS STEADY TO SLOWLY RISING SAT NGT THROUGH SUNDAY IF TRACK REMAINS UNCHANGED NEAR TO OVER THE CWA. WITH DEWPTS WELL IN THE 40S TO POSSIBLY EVEN LOWER 50S SAT NGT INTO SUNDAY WOULD EXPECT SOME GOOD ADVECTION FOG OVER THE COLDER SNOW COVERED GROUND... WHICH COULD BE QUITE DENSE. MON-WED... RISK OF RAIN CHANGING TO SNOW SUNDAY NGT LINGERING MON ESPECIALLY WITH DEFORMATION ZONE IF SYSTEM SLOWER TO WEAKEN... AND WILL HAVE TO WATCH SUN NGT INTO MON ONCE AGAIN FOR SOME ACCUMULATING SNOW POTENTIAL. OTHERWISE... MAINLY BELOW NORMAL TEMPS MON-WED WITH SOME SUGGESTION OF CLIPPER SYSTEM AND CHC OF LIGHT SNOW SOMETIME IN TUE-WED TIMEFRAME... BUT THIS ALL DEPENDENT ON EVOLUTION AND TIMING OF THE WEEKEND SYSTEM AND THUS FOR NOW HAVE NO MENTION. BEYOND FOR 7-10+ DAYS ... STRONG INDICATION OF CONTINUED BELOW NORMAL TEMPS WITH PERIODIC CLIPPER SYSTEMS IN GENERALLY NORTHWEST FLOW ALOFT. 05 && .AVIATION... ISSUED AT 332 PM CST WED MAR 6 2013 SATELLITE TRENDS THROUGH 20Z/06 ARE NOW POINTING TO CLEARING DVLPG AT KCID PRIOR TO SUNSET AND POTENTIALLY AT KDBQ/KMLI/BRL AROUND OR SHORTLY AFT SUNSET. THUS CONDITIONS ARE EXPECTED TO IMPROVE TO VFR. LIGHT WINDS OVER THE SNOW FIELD AND CLEAR SKIES BRINGS THE THREAT OF FG DEVELOPING. IF FG DEVELOPS AFT SUNSET...THE POTENTIAL EXISTS FOR LIFR CONDITIONS DVLPG AFT 06Z/07. 08 && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ SYNOPSIS...08 SHORT TERM...08 LONG TERM...05
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1130 AM CST WED MAR 6 2013 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TODAY/... MAIN FORECAST CONCERN TODAY IS LINGERING STRATUS DECK AND WHETHER IT WILL DISSIPATE DURING THE AFTERNOON. SURFACE HIGH AND UPPER LEVEL RIDGE BUILD INTO THE STATE PAST 18Z TODAY AND BRING LIGHT FLOW TO THE FORECAST AREA. INVERSION STRENGTHENS AS DRIER AIR FILTER WITH THE UPPER RIDGE MOVING INTO THE STATE THIS AFTERNOON. STRATUS DECK EXTENDS UP INTO CANADA AND THE GENERALLY NORTH FLOW CONTINUES THROUGH AT LEAST MIDDAY BEFORE WINDS BECOME LIGHT AND VARIABLE. LOW CONFIDENCE WITH STRATUS DISSIPATING BEFORE 18Z AND EVEN AT ALL THROUGH THE AFTERNOON. VERY MINIMAL MIXING AND IF STRATUS DECK REMAINS IN PLACE WHEN SURFACE HIGH SLIDES OVER CENTRAL IOWA...THINKING IT WILL BECOME TRAPPED UNDERNEATH THE INVERSION INTO THIS EVENING OR POSSIBLY TOMORROW BEFORE THE WAA DEVELOPS ON THE BACKSIDE OF THE SURFACE HIGH. AS A RESULT...INCREASED SKY COVER THROUGH THE AFTERNOON WITH IT SLOWLY DISSIPATING PAST 21Z. THE 05Z HRRR KEEPS THE STRATUS GOING THROUGH THE AFTERNOON EXCEPT THE FAR SOUTHWEST. WRT TO TEMPS TODAY...LEANED TOWARD THE NAM FOR MAX TEMPS TODAY AS IT SEEMS TO HAVE A GOOD HANDLE ON THE STRATUS AS WELL. .LONG TERM /TONIGHT THROUGH TUESDAY/... RIDGE OF HIGH PRESSURE WILL MOVE ACROSS IOWA TONIGHT. STILL UNCERTAIN HOW WIDESPREAD THE STRATUS WILL BE OVERNIGHT. THE STRATUS WILL BE TOUGH TO GET RID OF OVERNIGHT IF IT SURVIVES TODAY WITH VERY LITTLE SUBSIDENCE OR STEERING FLOW IN PLACE. THE UNCERTAINTY WITH THE STRATUS LEAVES A WIDE RANGE IN POSSIBLE LOW TEMPERATURES OVERNIGHT. TEMPERATURES WILL DROP WELL INTO THE SINGLE DIGITS OVERNIGHT ACROSS THE NORTHEAST WITH CLEARING BUT WOULD REMAIN IN THE MID TO UPPER TEENS IF CLOUDS PERSIST. HAVE LEANED TOWARDS CLEARING OR PARTIAL CLEARING AND COLDER TEMPERATURES AT THIS TIME. THE HIGH PRESSURE RIDGE SHIFTS EAST ON THURSDAY WITH RETURN FLOW DEVELOPING IN ADDITION TO A TRANSITION TO MID LEVEL RIDGING. THIS WILL CONTINUE INTO FRIDAY WITH EVEN WARMER TEMPERATURES EXPECTED IN THE UPPER 30S TO UPPER 40S. A POTENT UPPER LEVEL SYSTEM CONSISTING OF SEVERAL STRONG SHORT WAVES ROTATING AROUND THE CORE WILL BEGIN TO MOVE OVER CALIFORNIA ON FRIDAY. ANOTHER SHORT WAVE UNDERCUTTING THE SYSTEM WILL PUSH OUT AHEAD AND ARRIVE OVER NEBRASKA AND IOWA BY FRIDAY NIGHT. AN INCREASING LOW LEVEL JET AND ASSOCIATED STRONG THETA-E ADVECTION ALONG WITH THE QG FORCING FROM THE UPPER WAVE WILL HELP SHOWERS AND A FEW THUNDERSTORMS DEVELOP ACROSS MAINLY CENTRAL AND WESTERN IOWA. OVERNIGHT LOW TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE FREEZING WITH LOW LEVEL MOISTURE SURGE BRINGING DEWPOINTS IN THE 3OS TO THE AREA. THE FORECAST AREA WILL BE IN THE WARM SECTOR THROUGH THE DAY SATURDAY. THE PRIMARY UPPER LEVEL SYSTEM WILL LIFT INTO THE MIDWEST SATURDAY NIGHT INTO SUNDAY. THE ECMWF IS A BIT FASTER WITH THE SFC FEATURES WITH THE COLD FRONT DROPPING THROUGH MUCH OF CENTRAL IOWA BY 12Z SUNDAY WHILE THE GFS IS A BIT SLOWER. ANY PRECIPITATION WILL SWITCH OVER TO SNOW BEHIND THE COLD FRONT AS PROFILES COOL. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE. COLD ADVECTION WILL BE PROMINENT MUCH OF THE DAY SUNDAY WITH HIGH TEMPERATURES EARLY IN THE DAY. 850 MB TEMPERATURES BY 12Z MONDAY WILL BE -8C TO -10C ACROSS MUCH OF THE AREA AND HAVE CONTINUED THE COOLING TREND INTO MONDAY. SOME MODERATION FOR THE END OF THE PERIOD WITH LOW CHANCES FOR PRECIPITATION. && .AVIATION...06/18Z STRATUS WILL PERSIST ACROSS THE AREA THROUGH THE PERIOD. CEILINGS WILL VARY BETWEEN LOW MVFR AND HIGH IFR AT TIMES...AND MAY OCCASIONALLY SCATTER TO VFR AT SITES. HOWEVER...OVERALL TREND WILL BE FOR MVFR CEILINGS. COULD SEE SOME BR/FG DEVELOP AT EASTERN SITES KMCW/KALO/KOTM NEAR 12Z AS INVERSION SETS UP...BUT DO NOT HAVE ENOUGH CONFIDENCE TO INCLUDE MENTION ATTM. NORTHWESTERLY WINDS WILL DECREASE IN THE AFTERNOON BEFORE SHIFTING TO THE SOUTHEAST LATE IN THE PERIOD AND WILL BE STRONG AFTER 12Z. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...AWB
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1050 AM CST WED MAR 6 2013 .UPDATE... BASED ON DATA THROUGH MID MORNING...CLEARING TODAY IS DOUBTFUL AND QUESTIONABLE FOR TONIGHT. SATELLITE DOES SHOW HOLES IN THE CLOUD COVER THAT IS APPROXIMATED BY THE 0.5 KM RH OF THE RAP. THE 12Z UA DATA SHOWED A THIN LAYER OF MOISTURE TRAPPED BELOW THE INVERSION. RAP TRENDS WITH CONDENSATION PRESSURES AND WIND AT THE 0.5 KM LEVEL DO NOT SHOW ANY SUBSTANTIAL FORCING TO HELP BREAK UP THE CLOUDS TODAY IN SPITE OF THE STRONGER MARCH SUNSHINE. THE 0.5 KM CONDENSATION PRESSURE SUGGESTS THE HOLE ALONG THE MISS RIVER IN WESTERN WISCONSIN MAY DRIFT SLOWLY SOUTH DURING THE DAY AND POSSIBLY CLIP THE FAR NORTHWEST PARTS OF THE CWFA. IF THE RAP TRENDS ARE CORRECT...THEN CLOUDS MAY NOT BREAK UP TONIGHT OR ONLY A FEW HOLES MAY DEVELOP. SO...WILL UPDATE THE FCST TO BE MORE PESSIMISTIC ON CLEARING TODAY AND AT LEAST INTO THE EVENING HOURS. ..08.. && .AVIATION... MOISTURE TRAPPED BELOW THE INVERSION IS RAISING QUESTIONS ON THE MVFR CONDITIONS CLEARING LATER TODAY. RAP MODEL TRENDS SUGGESTS THE THIN LAYER OF MOISTURE REMAINS TRAPPED AND MAY REMAIN IN PLACE UNTIL AFTER 12Z/07. THE POTENTIAL DOES EXIST FOR BREAKS IN THE CLOUD COVER THAT COULD ALLOW POCKETS OF VFR CONDITIONS TO DVLP BUT MAY NOT NECESSARILY BE OVER ANY TAF SITE. ..08.. && .PREV DISCUSSION... /ISSUED 541 AM CST WED MAR 6 2013/ SYNOPSIS... ISSUED AT 331 AM CST WED MAR 6 2013 CONDITIONS MUCH QUIETER TONIGHT WITH THE STRONG SURFACE LOW ASSOCIATED WITH THE TUESDAY SNOW NOW EXITING EAST ACROSS OHIO AS OF 3 AM THIS MORNING. NORTHWEST FLOW CONTINUES ACROSS THE AREA WITH WIDESPREAD LOW CLOUDS. A FEW FLURRIES WERE LINGERING OVER THE AREA AROUND MIDNIGHT...BUT THESE HAVE SINCE DISSIPATED. THERE ARE SOME HOLES IN THE STRATUS...BUT THESE ARE RELATIVELY TRANSITORY AND ARE NOT VISIBLY EXPANDING. IT APPEARS TO BE LOOSELY RELATED TO SOME MID LEVEL DIVERGENCE...WHICH IS SLOWLY SHIFTING SOUTH ACROSS THE AREA OVERNIGHT. THIS DIVERGENCE WEAKENS AND SHIFTS OUT OF THE AREA IN THE NEXT SEVERAL HOURS. WILL BE WATCHING TRENDS TO SEE IF THE STRATUS FILLS BACK IN. ..LE.. SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 331 AM CST WED MAR 6 2013 THE MAIN CONCERN BOTH PERIODS IS FOR HOW THE STRATUS EVOLVES OVER THE NEXT 24 HOURS...AND ITS RELATED EFFECT ON TEMPERATURES. TODAY...MODEL GUIDANCE IS PERSISTENT IN BREAKING UP THE LOW STRATUS DURING LATE MORNING OR AFTERNOON HOURS. NONE OF THE MODEL GUIDANCE IS DOING ESPECIALLY WELL WITH THESE LOW CLOUDS...MOST NOT DEPICTING ENOUGH AREAL EXTENT AT INITIALIZATION. HOWEVER...A MORE DETAILED LOOK AT 925MB RH GRIDS AND SOUNDINGS IMPLIES A MORE PESSIMISTIC PICTURE. THIS LOW LEVEL RH IS TRAPPED BENEATH A LOW LEVEL INVERSION...WHICH LIFTS DURING THE DAYTIME...BUT DOES NOT BREAK. EXPECT THAT THE CEILINGS MAY LIFT INTO A MORE MVFR LAYER...BUT WILL STILL BE THERE. ALSO...WE DO NOT HAVE ANY PARTICULARLY DRY AIR OR PARTICULARLY STRONG SUBSIDENCE WORKING INTO THE AREA TODAY. HOWEVER...THIS IS EARLY MARCH AND WE ARE WORKING WITH FAIRLY STRONG SUNSHINE...AND CLOUDS MAY BREAK UP AS DEPICTED. SO...WHILE AM NOT TERRIBLY OPTIMISTIC...HAVE ALLOWED CLOUD COVER TO DECREASE THIS AFTERNOON. THE EFFECT ON TODAYS HIGH TEMPS WILL NOT BE VERY NOTICEABLE...AND WITH THE WEAK COLD AIR ADVECTION STILL ONGOING...EXPECT HIGHS IN THE UPPER 20S TO LOW 30S. TONIGHT THE REAL TROUBLE WITH THE STRATUS KICKS IN...AS IT COULD HAVE A FAIRLY MAJOR EFFECT ON THE MIN TEMPS TONIGHT. AGAIN...NEARLY ALL GUIDANCE IMPLIES THAT WE WILL CLEAR OUT DURING THE AFTERNOON AND BE CLEAR OR NEARLY CLEAR OVERNIGHT. MODEL GUIDANCE FOLLOWS THIS WITH MIN TEMPS IN THE SINGLE DIGITS NORTH AND LOWER TEENS SOUTH. ONCE AGAIN THOUGH...925MB RH VALUES IMPLY A PERSISTENT LAYER OF RH...WITH NO STRONG FEATURES TO DRIVE THE LOW LEVEL RH OUT OF THE AREA. SOUNDINGS ALSO SUPPORT THIS TRAPPED LOW LEVEL MOISTURE. RIGHT NOW THE STRATUS EXTENDS BACK TO THE SURFACE RIDGE AXIS IN NEBRASKA AND THE DAKOTAS...AND SEE NO FEATURES IN THE FORECAST OTHER THAN SUNSHINE THAT COULD POSSIBLY MIX THE STUFF OUT DURING THE DAYTIME OR EARLY EVENING. SO...IF WE CANNOT CLEAR THE STRATUS DURING THE AFTERNOON...WE MAY HAVE CLOUD COVER FOR THE OVERNIGHT TO PUT A BLANKET ON THE RADIATIONAL COOLING. WITH CLOUD COVER...EXPECT ANOTHER NIGHT IN THE UPPER TEENS TO LOW 20S. THUS...WE HAVE A FAIRLY LARGE BUST POTENTIAL FOR TONIGHT WITH THIS SKY COVER DILEMMA. FOR NOW HAVE THE MOSTLY CLEAR SKIES GOING IN THE FORECAST...WITH THE COLDER SCENARIO FOR MIN TEMPERATURES...BUT THE NEXT SHIFT IS GOING TO HAVE TO REEVALUATE THOSE LOW CLOUDS AND WHETHER THEY ARE GOING TO PERSIST INTO THE NIGHTTIME HOURS OR NOT. .LE.. LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 331 AM CST WED MAR 6 2013 PRIMARY FOCUS IS ON A WARMING TREND AND RAIN CHANCES THIS WEEKEND. THIS WILL OCCUR AS THE UPPER LOW CURRENTLY OFF THE PACIFIC NW COAST IS PROGGED TO DIG INTO THE 4 CORNERS REGION FRIDAY NIGHT...THEN LIFT NORTHEAST INTO THE CENTRAL U.S. BY SUNDAY AND MONDAY. AHEAD OF THIS...A SW FLOW WILL FEED GULF MOISTURE INTO THE PLAINS BY FRIDAY...REACHING INTO THE LOCAL FORECAST AREA SATURDAY. AT THE SURFACE...LOW PRESSURE EMERGES TO LEE OF THE CENTRAL ROCKIES INTO THE PLAINS FRIDAY NIGHT...THEN LIFTS NORTHEAST ALONG A SW TO NE ORIENTED FRONTAL AXIS...THROUGH THE MID OR UPPER MS VALLEY OVER THE WEEKEND. WHILE THE LATEST MODELS HAVE COME INTO BETTER AGREEMENT WITH THIS OVERALL SCENARIO THAN LAST NIGHT/S RUNS...THERE REMAIN CONSIDERABLE DIFFERENCES WITH THE TRACK AND TIMING OF THE SURFACE LOW AND THE ASSOCIATED AMOUNT OF PHASING OF UPPER LEVEL WAVES. THE ECMWF REMAINS SLOWER AND DOES NOT DEPICT THE GFS/S PHASING OF THE 500 MB LOW MOVING OUT OF THE SW WITH A NORTHERN STREAM TROUGH MOVING ACROSS SOUTHERN CANADA. THIS RESULTS IN THE GFS BECOMING A MUCH MORE PROGRESSIVE SOLUTION AND TAKING THE SURFACE LOW ON A MORE NORTHERLY TRACK...ESPECIALLY SUNDAY AND BEYOND. FOR NOW...WILL PREFER THE SLOWER ECMWF...BASED ON EXPERIENCE WITH SIMILAR COOL SEASON SYSTEMS LIFTING OUT OF THE SW. THURSDAY AND FRIDAY WILL BE PROGRESSIVELY WARMER AS THE SURFACE RIDGE SHIFTS EAST OVER THE GREAT LAKES AND WARM ADVECTION INCREASES ALOFT. DESPITE THE SNOW COVER...STRONG MARCH SUNSHINE SHOULD WARM MOST AREAS ABOVE FREEZING TO REACH HIGHS IN THE 30S THURSDAY...THEN INTO THE UPPER 30S NORTH TO NEAR 50 SOUTH ON FRIDAY WHEN SOUTHEAST WINDS WILL BE STRONGER. THU NIGHT...LOWS RANGE FROM THE UPPER TEENS NORTHEAST TO MID 20S SOUTHWEST...COUNTING ON AT LEAST SCATTERED MID CLOUDS AND LIGHT WINDS TO PREVENT POSSIBLE COLDER READINGS OVER THE LINGERING SNOW COVER. FRIDAY NIGHT...STRONG WARM ADVECTION ON 850 MB WINDS OF 25 TO 35 KTS WILL REACH INTO THE AREA BY MORNING. MOISTURE RETURN...HOWEVER...IS MAINLY CONFINED TO THE SW OR WESTERN REACHES OF THE FORECAST AREA TOWARD MORNING DEPENDING ON THE MODEL. THIS MAY TRIGGER SOME SHOWERS AND HAVE SLIGHT CHANCES IN PLACE IN THE WEST AFTER MIDNIGHT. THERE IS A POSSIBILITY THAT SURFACE TEMPERATURES COULD BE NEAR OR BELOW FREEZING AT ONSET ESPECIALLY ACROSS THE NORTH FOR A THREAT OF BRIEF FREEZING RAIN...BUT CONFIDENCE IS TOO LOW TO INCLUDE MENTION IN THE FORECAST. SATURDAY AND SATURDAY NIGHT...THE MAIN FEED OF GULF MOISTURE OVERSPREADS THE AREA UNDER AN INCREASINGLY DIFFLUENT FLOW ALOFT AND LIKELY POPS ARE IN PLACE FOR RAIN IN THE WEST DURING THE DAY AND OVER THE ENTIRE AREA SATURDAY NIGHT FOR WHAT COULD BE WIDESPREAD MODERATE AMOUNTS. SUNDAY...THE COLD FRONT PUSHES THROUGH THE AREA IN SOME FASHION...LIKELY CHANGING THE RAIN TO SNOW FROM NW TO SE BY EVENING AND CANNOT RULE OUT SOME SNOW ACCUMULATIONS AS PRECIPITATION CONTINUES SUNDAY NIGHT. HIGHS SATURDAY AND SUNDAY SHOULD BE WELL INTO THE 40S AND POSSIBLY LOWER 50S...FOLLOWED BY 30S AND POSSIBLY LOWER 40S EARLY NEXT WEEK AS THE UPPER FLOW BECOMES NW AND HIGH PRESSURE BUILDS INTO THE UPPER MS VALLEY. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
547 AM CST WED MAR 6 2013 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TODAY /... MAIN FORECAST CONCERN TODAY IS LINGERING STRATUS DECK AND WHETHER IT WILL DISSIPATE DURING THE AFTERNOON. SURFACE HIGH AND UPPER LEVEL RIDGE BUILD INTO THE STATE PAST 18Z TODAY AND BRING LIGHT FLOW TO THE FORECAST AREA. INVERSION STRENGTHENS AS DRIER AIR FILTER WITH THE UPPER RIDGE MOVING INTO THE STATE THIS AFTERNOON. STRATUS DECK EXTENDS UP INTO CANADA AND THE GENERALLY NORTH FLOW CONTINUES THROUGH AT LEAST MIDDAY BEFORE WINDS BECOME LIGHT AND VARIABLE. LOW CONFIDENCE WITH STRATUS DISSIPATING BEFORE 18Z AND EVEN AT ALL THROUGH THE AFTERNOON. VERY MINIMAL MIXING AND IF STRATUS DECK REMAINS IN PLACE WHEN SURFACE HIGH SLIDES OVER CENTRAL IOWA...THINKING IT WILL BECOME TRAPPED UNDERNEATH THE INVERSION INTO THIS EVENING OR POSSIBLY TOMORROW BEFORE THE WAA DEVELOPS ON THE BACKSIDE OF THE SURFACE HIGH. AS A RESULT...INCREASED SKY COVER THROUGH THE AFTERNOON WITH IT SLOWLY DISSIPATING PAST 21Z. THE 05Z HRRR KEEPS THE STRATUS GOING THROUGH THE AFTERNOON EXCEPT THE FAR SOUTHWEST. WRT TO TEMPS TODAY...LEANED TOWARD THE NAM FOR MAX TEMPS TODAY AS IT SEEMS TO HAVE A GOOD HANDLE ON THE STRATUS AS WELL. .LONG TERM /TONIGHT THROUGH TUESDAY/... RIDGE OF HIGH PRESSURE WILL MOVE ACROSS IOWA TONIGHT. STILL UNCERTAIN HOW WIDESPREAD THE STRATUS WILL BE OVERNIGHT. THE STRATUS WILL BE TOUGH TO GET RID OF OVERNIGHT IF IT SURVIVES TODAY WITH VERY LITTLE SUBSIDENCE OR STEERING FLOW IN PLACE. THE UNCERTAINTY WITH THE STRATUS LEAVES A WIDE RANGE IN POSSIBLE LOW TEMPERATURES OVERNIGHT. TEMPERATURES WILL DROP WELL INTO THE SINGLE DIGITS OVERNIGHT ACROSS THE NORTHEAST WITH CLEARING BUT WOULD REMAIN IN THE MID TO UPPER TEENS IF CLOUDS PERSIST. HAVE LEANED TOWARDS CLEARING OR PARTIAL CLEARING AND COLDER TEMPERATURES AT THIS TIME. THE HIGH PRESSURE RIDGE SHIFTS EAST ON THURSDAY WITH RETURN FLOW DEVELOPING IN ADDITION TO A TRANSITION TO MID LEVEL RIDGING. THIS WILL CONTINUE INTO FRIDAY WITH EVEN WARMER TEMPERATURES EXPECTED IN THE UPPER 30S TO UPPER 40S. A POTENT UPPER LEVEL SYSTEM CONSISTING OF SEVERAL STRONG SHORT WAVES ROTATING AROUND THE CORE WILL BEGIN TO MOVE OVER CALIFORNIA ON FRIDAY. ANOTHER SHORT WAVE UNDERCUTTING THE SYSTEM WILL PUSH OUT AHEAD AND ARRIVE OVER NEBRASKA AND IOWA BY FRIDAY NIGHT. AN INCREASING LOW LEVEL JET AND ASSOCIATED STRONG THETA-E ADVECTION ALONG WITH THE QG FORCING FROM THE UPPER WAVE WILL HELP SHOWERS AND A FEW THUNDERSTORMS DEVELOP ACROSS MAINLY CENTRAL AND WESTERN IOWA. OVERNIGHT LOW TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE FREEZING WITH LOW LEVEL MOISTURE SURGE BRINGING DEWPOINTS IN THE 3OS TO THE AREA. THE FORECAST AREA WILL BE IN THE WARM SECTOR THROUGH THE DAY SATURDAY. THE PRIMARY UPPER LEVEL SYSTEM WILL LIFT INTO THE MIDWEST SATURDAY NIGHT INTO SUNDAY. THE ECMWF IS A BIT FASTER WITH THE SFC FEATURES WITH THE COLD FRONT DROPPING THROUGH MUCH OF CENTRAL IOWA BY 12Z SUNDAY WHILE THE GFS IS A BIT SLOWER. ANY PRECIPITATION WILL SWITCH OVER TO SNOW BEHIND THE COLD FRONT AS PROFILES COOL. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE. COLD ADVECTION WILL BE PROMINENT MUCH OF THE DAY SUNDAY WITH HIGH TEMPERATURES EARLY IN THE DAY. 850 MB TEMPERATURES BY 12Z MONDAY WILL BE -8C TO -10C ACROSS MUCH OF THE AREA AND HAVE CONTINUED THE COOLING TREND INTO MONDAY. SOME MODERATION FOR THE END OF THE PERIOD WITH LOW CHANCES FOR PRECIPITATION. && .AVIATION... MVFR STRATUS WILL CONTINUE THROUGH MUCH OF THE DAY AND POSSIBLY INTO TONIGHT. CONFIDENCE IS GROWING WITH THIS STRATUS PERSISTING INTO THURSDAY MORNING AS HIRES MODELS KEEP IT THROUGH LATE THIS AFTERNOON AND WITH THE HIGH BUILDING INTO THE STATE...EXPECTING INVERSION TO HOLD IT IN PLACE THROUGH TONIGHT. MOS GUIDANCE REDEVELOPS MVFR STRATUS BY 03Z THURSDAY. HAVE BRIEF BREAK IN THE MVFR CIGS THIS AFTERNOON...BUT BRING IT BACK IN LATE TONIGHT INTO THE OVERNIGHT HOURS. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...PODRAZIK
AREA FORECAST DISCUSSION
NWS DES MOINES IA
356 AM CST WED MAR 6 2013 .SHORT TERM /TODAY /... MAIN FORECAST CONCERN TODAY IS LINGERING STRATUS DECK AND WHETHER IT WILL DISSIPATE DURING THE AFTERNOON. SURFACE HIGH AND UPPER LEVEL RIDGE BUILD INTO THE STATE PAST 18Z TODAY AND BRING LIGHT FLOW TO THE FORECAST AREA. INVERSION STRENGTHENS AS DRIER AIR FILTER WITH THE UPPER RIDGE MOVING INTO THE STATE THIS AFTERNOON. STRATUS DECK EXTENDS UP INTO CANADA AND THE GENERALLY NORTH FLOW CONTINUES THROUGH AT LEAST MIDDAY BEFORE WINDS BECOME LIGHT AND VARIABLE. LOW CONFIDENCE WITH STRATUS DISSIPATING BEFORE 18Z AND EVEN AT ALL THROUGH THE AFTERNOON. VERY MINIMAL MIXING AND IF STRATUS DECK REMAINS IN PLACE WHEN SURFACE HIGH SLIDES OVER CENTRAL IOWA...THINKING IT WILL BECOME TRAPPED UNDERNEATH THE INVERSION INTO THIS EVENING OR POSSIBLY TOMORROW BEFORE THE WAA DEVELOPS ON THE BACKSIDE OF THE SURFACE HIGH. AS A RESULT...INCREASED SKY COVER THROUGH THE AFTERNOON WITH IT SLOWLY DISSIPATING PAST 21Z. THE 05Z HRRR KEEPS THE STRATUS GOING THROUGH THE AFTERNOON EXCEPT THE FAR SOUTHWEST. WRT TO TEMPS TODAY...LEANED TOWARD THE NAM FOR MAX TEMPS TODAY AS IT SEEMS TO HAVE A GOOD HANDLE ON THE STRATUS AS WELL. .LONG TERM /TONIGHT THROUGH TUESDAY/... RIDGE OF HIGH PRESSURE WILL MOVE ACROSS IOWA TONIGHT. STILL UNCERTAIN HOW WIDESPREAD THE STRATUS WILL BE OVERNIGHT. THE STRATUS WILL BE TOUGH TO GET RID OF OVERNIGHT IF IT SURVIVES TODAY WITH VERY LITTLE SUBSIDENCE OR STEERING FLOW IN PLACE. THE UNCERTAINTY WITH THE STRATUS LEAVES A WIDE RANGE IN POSSIBLE LOW TEMPERATURES OVERNIGHT. TEMPERATURES WILL DROP WELL INTO THE SINGLE DIGITS OVERNIGHT ACROSS THE NORTHEAST WITH CLEARING BUT WOULD REMAIN IN THE MID TO UPPER TEENS IF CLOUDS PERSIST. HAVE LEANED TOWARDS CLEARING OR PARTIAL CLEARING AND COLDER TEMPERATURES AT THIS TIME. THE HIGH PRESSURE RIDGE SHIFTS EAST ON THURSDAY WITH RETURN FLOW DEVELOPING IN ADDITION TO A TRANSITION TO MID LEVEL RIDGING. THIS WILL CONTINUE INTO FRIDAY WITH EVEN WARMER TEMPERATURES EXPECTED IN THE UPPER 30S TO UPPER 40S. A POTENT UPPER LEVEL SYSTEM CONSISTING OF SEVERAL STRONG SHORT WAVES ROTATING AROUND THE CORE WILL BEGIN TO MOVE OVER CALIFORNIA ON FRIDAY. ANOTHER SHORT WAVE UNDERCUTTING THE SYSTEM WILL PUSH OUT AHEAD AND ARRIVE OVER NEBRASKA AND IOWA BY FRIDAY NIGHT. AN INCREASING LOW LEVEL JET AND ASSOCIATED STRONG THETA-E ADVECTION ALONG WITH THE QG FORCING FROM THE UPPER WAVE WILL HELP SHOWERS AND A FEW THUNDERSTORMS DEVELOP ACROSS MAINLY CENTRAL AND WESTERN IOWA. OVERNIGHT LOW TEMPERATURES ARE EXPECTED TO BE AT OR ABOVE FREEZING WITH LOW LEVEL MOISTURE SURGE BRINGING DEWPOINTS IN THE 3OS TO THE AREA. THE FORECAST AREA WILL BE IN THE WARM SECTOR THROUGH THE DAY SATURDAY. THE PRIMARY UPPER LEVEL SYSTEM WILL LIFT INTO THE MIDWEST SATURDAY NIGHT INTO SUNDAY. THE ECMWF IS A BIT FASTER WITH THE SFC FEATURES WITH THE COLD FRONT DROPPING THROUGH MUCH OF CENTRAL IOWA BY 12Z SUNDAY WHILE THE GFS IS A BIT SLOWER. ANY PRECIPITATION WILL SWITCH OVER TO SNOW BEHIND THE COLD FRONT AS PROFILES COOL. SOME SNOW ACCUMULATIONS WILL BE POSSIBLE. COLD ADVECTION WILL BE PROMINENT MUCH OF THE DAY SUNDAY WITH HIGH TEMPERATURES EARLY IN THE DAY. 850 MB TEMPERATURES BY 12Z MONDAY WILL BE -8C TO -10C ACROSS MUCH OF THE AREA AND HAVE CONTINUED THE COOLING TREND INTO MONDAY. SOME MODERATION FOR THE END OF THE PERIOD WITH LOW CHANCES FOR PRECIPITATION. && .AVIATION...06/06Z MVFR STRATUS CONTINUES TO STREAM ACROSS THE STATE FROM THE NNW WITH A FEW PATCHES OF VFR CONDITIONS SCATTERED ABOUT IOWA AND MINNESOTA. THE VFR CEILINGS HAVE BEEN DECREASING IN COVERAGE OVER THE LAST COUPLE OF HOURS SO HAVE NOT MENTIONED ANYTHING HIGHER THAN MVFR IN THE TAF PACKAGE. HIGH IFR CEILINGS ARE POSSIBLE ACROSS THE NORTH TONIGHT AS WELL. HAVE CONTINUED TO PUSH BACK THE CLEARING OF THE STRATUS INTO THE MID MORNING TOMORROW GIVEN THE LARGE SHIELD OF STRATUS EXTENDING UPSTREAM INTO MN AND MANITOBA. && .DMX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...DONAVON AVIATION...KS
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1034 AM EST WED MAR 6 2013 .SYNOPSIS... SNOW WILL DIMINISH AS LOW PRESSURE CONTINUES MOVING EASTWARD. && .NEAR TERM /THROUGH TONIGHT/... THE BAND OF SNOW ASSOCIATED WITH THE DEFORMATION ZONE CONTINUES TO DIMINISH AS IT SHIFTS TO THE SOUTH OVER SW PA THIS MORNING. THUS...HAVE CANCELLED THE ADVISORY FOR BUTLER AND ARMSTRONG COUNTIES. THE HRRR SEEMS TO BE HANDLING THIS BAND WELL SO HAVE ADJUSTED POPS ACCORDINGLY BASED OFF OF CURRENT RADAR AND HRRR MODEL TRENDS. WITH DEFORMATION SNOWS LASTING LONGEST OVER THE RIDGES...THINK THEY WILL EASILY SEE ANOTHER 2-5 INCHES OF SNOW AND WILL KEEP THE WARNING GOING FOR NOW. OTHERWISE...ONLY SMALL ADJUSTMENTS WERE NEEDED TO TEMPS...DEWPOINTS...AND WINDS THROUGH THE AFTERNOON. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... STILL TRYING TO GET A GOOD HANDLE OF SNOW POSSIBILITIES FOR THURSDAY INTO THURSDAY NIGHT. MODELS ARE NOW SHOWING A WEAK UPPER LEVEL WAVE DROPPING ACROSS ONTARIO...WITH THE BEST MOISTURE AND DYNAMICS EXPECTED TO CROSS NEW YORK AND CENTRAL/EASTERN PENNSYLVANIA. HAVE ADDED A SLIGHT CHANCE OF PRECIPITATION INTO THE FORECAST NORTH AND EAST OF PITTSBURGH. WIND DIRECTIONS WILL BE CRITICAL TO WHETHER ANY FLAKES ARE SEEN IN THE UPSLOPE REGIONS OF PA/WV/MD. CURRENTLY HAVE A NORTHWEST WIND WHICH WOULD ALLOW FOR SOME VERY LIGHT UPSLOPE SNOW...BUT IF WIND DIRECTIONS ARE MORE NORTHERLY SUCH AS SHOWN IN THE NAM...WOULD NOT EXPECT TO SEE ANY SNOW TO THE SOUTH. HIGH PRESSURE WILL THEN BUILD IN FOR THURSDAY NIGHT AND FRIDAY...BRINGING DRY CONDITIONS TO ALL LOCATIONS. TEMPERATURES WILL RISE A FEW DEGREES FROM WEDNESDAY READINGS...BUT STILL REMAIN A COUPLE OF DEGREES BELOW NORMAL. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... MODELS ARE IN GOOD AGREEMENT WITH DEPICTIONS OF SATURDAY WEATHER...BUT DIVERGENT SOLNS QUICKLY ERODE LONG TERM FORECAST CONFIDENCE. FAIRLY BROAD AND AMPLIFIED ERN CONUS RIDGE IS EXPECTED TO BE BROKEN DOWN DURING THE PD...ALBEIT WITH QNABLE TIMING. PERSISTENCE/COLLABORATED LONG TERM PROGNOSIS THUS FEATURES TEMPS AT...OR ABOVE THE SEASONAL AVERAGES ACCOMPANIED BY GRADUALLY INCRSG PCPN PROBABILITIES TO NR CLIMO NMBRS THRU EARLY NXT WEEK. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... AREA OF LINGERING SN BTN PIT...LBE AND MGW WL GRADUALLY DIMINISH BY THIS AFTN. VFR CONDITIONS MAY BRIEFLY RTN AS SBSDNC INCRS IN THE WAKE OF THE EXITING LOW...BUT MORE RESTRICTION IN STRATOCU...AND POSSIBLY SOME FOG ARE ANTICIPATED OVRNGT AND INTO EARLY THURSDAY. .OUTLOOK.../THURSDAY THROUGH SATURDAY/... GENL VFR CONDITIONS ARE ANTICIPATED FOR THE END OF THE WEEK AS HIGH PRES BLDS OVR THE REGION. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR MDZ001. OH...NONE. PA...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR PAZ021- 029-031-073-075. WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR PAZ074- 076. WINTER WEATHER ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR PAZ023. WV...WINTER STORM WARNING UNTIL 5 PM EST THIS AFTERNOON FOR WVZ021- 022. WINTER STORM WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ023- 041. && $$
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
942 AM EST WED MAR 6 2013 .SYNOPSIS... STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... STACKED LOW PRESSURE OVER THE HAMPTONS WILL SLOWLY PUSH OFFSHORE THROUGH THIS AFTERNOON. WINDS HAVE SHIFTED TO THE NNE OVER THE I95 CORRIDOR...AND PRECIPITATION HAS CHANGED OVER TO HEAVY SNOW. AREAS TO THE SOUTHEAST OF BALTIMORE/DC SHOULD CHANGE OVER TO SNOW AS WELL OVER THE NEXT SEVERAL HOURS. GIVEN THE DURATION OF RAINFALL OVER THE REGION SO FAR THIS MORNING...HAVE LOWERED SNOW TOTALS ALONG AND EAST OF I-95...BUT MAINTAINING WINTER STORM WARNING FOR THE ENTIRE AREA. ALSO ADDED ISOLATED THUNDER TO AREAS S OF THE DC METRO. CONVECTION CURRENTLY OCCURRING OVER SE VA MAY ROTATE NWD INTO THE PIEDMONT AND SRN MD. ONE STRIKE WAS NOTED EARLIER OVER CULPEPER COUNTY...AND FORECAST SOUNDINGS INDICATE ELEVATED INSTABILITY. PRECIP IS EXPECTED TO CONTINUE THROUGH THE AFTERNOON. BANDS OF HEAVIER PRECIP EXPECTED TO ROTATE AROUND THE NORTH AND WEST SIDE OF THE LOW...AS LIFT CONTINUES TO BE STRONG. HRRR ADVERTISES ONE SUCH BAND ROTATING AROUND THE DC METRO AREA THROUGH LATE AFTERNOON...AND OTHER BANDING ACTIVITY ALONG AND WEST OF THE BLUE RIDGE WHERE SIGNIFICANT SNOWFALL HAS ALREADY FALLEN. A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER INTO THE EARLY MRNG HRS THU. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME. ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS SHOWING CLEAR TO PARTLY CLOUDY SKIES. NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY. CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR I-95. EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE. GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... SNOW CONTINUES THROUGH TODAY. VSBYS WILL FLUCTUATE FROM MVFR TO LIFR AS HEAVIER BANDS OF SNOW MOVE THROUGH THE TERMINALS. INTENSE SNOWFALL RATES...GUSTY WINDS AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND INTO THU. PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH PRESSURE THIS WEEKEND. && .MARINE... GALE FORCE WIND GUSTS CONTINUE TODAY...AS A SFC LOW SLOWLY MOVES EWD OFF THE COAST NEAR NORFOLK. SOLID GALE GUSTS WILL STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE GALE RANGE OVERNIGHT. WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK. && .HYDROLOGY... WILL BE WATCHING SNOWMELT OVER THE NEXT SEVERAL DAYS. ALREADY HAVE NUMEROUS REPORTS OF OVER A FOOT OF SNOW. A GRADUAL MELT SEEMS MOST LIKELY BUT WILL HAVE TO KEEP AN EYE ON IT THROUGH THE END OF THE WEEK. && .TIDES/COASTAL FLOODING... WINDS ARE NOW OUT OF THE NORTHEAST IN THE TIDAL ZONE...BUT OUT OF THE EAST JUST ACROSS THE EASTERN SHORE. LEWISETTA IS OVERACHIEVING THE MODEL FORECAST...NEAR MODERATE FLOOD LEVEL. COASTAL FLOOD ADVISORY IS STILL OUT FOR THE WESTERN SHORE EXCEPT HARFORD...AND THE ST. MARYS PORTION OF THE TIDAL POTOMAC. NEW GUIDANCE FROM MARFC TAKES THE UPPER POTOMAC TO MINOR FLOOD ALSO LATER TODAY. NOT SO SURE ABOUT THAT JUST YET GIVEN THE NORTH WIND...BUT WILL MONITOR FOR THE NEED TO ADD ANYTHING TO THE ADVISORY. AS WINDS TURN NORTHERLY LATE TODAY...GIVEN THEIR EXPECTED STRENGTH...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER IN THE UPPER BAY. FORECAST MODEL STILL SHOWS A LITTLE WATER TRAPPING IN THE LOWERMOST TIDAL POTOMAC...AND WILL HAVE TO WATCH TRENDS TO SEE IF ANOTHER ADVISORY IS NEEDED FOR ST. MARYS COUNTY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001. MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501- 502. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007- 009>011-013-014-016>018. COASTAL FLOOD ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR MDZ014-017-018. COASTAL FLOOD ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MDZ011. VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031- 503-504. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040- 042-050>057-501-502. WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053- 055-501>506. MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535- 536. GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536. && $$ SYNOPSIS...BPP/GMS NEAR TERM...GMS/KCS SHORT TERM...BPP LONG TERM...JRK AVIATION...KCS/BPP/JRK MARINE...JRK/BPP/KCS HYDROLOGY...JE TIDES/COASTAL FLOODING...JE
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
837 AM EST WED MAR 6 2013 .SYNOPSIS... STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AT 0830AM...QUICK UPDATE MADE TO MORNING FCST BASED ON CURRENT RADAR/OBS. RAIN/SNOW LINE IS JUST TO SOUTHEAST OF A LINE FROM BWI/ADW/DCA. SOUTHEAST OF THIS LINE...MOSTLY RAIN IS FALLING WITH SURFACE TEMPS IN UPPER 30S...TO EVEN LOW 40S OVER SRN MD. LOW PRESSURE IS NOW OVER THE NORFOLK METRO AREA...WITH AN EASTERLY WIND ADVECTING MARINE AIR OVER SRN MD. AS THE BOTH THE SURFACE AND UPPER LOW MOVE TOWARDS THE NORTH DURING THE DAY TODAY...WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND DRAW IN COOLER AIR. FOR THIS REASON...STILL EXPECTING A CHANGEOVER TO SNOW ALONG AND EAST OF THE I-95 CORRIDOR. ADJUSTED SNOWFALL TOTALS DOWN S AND E OF BWI/DCA BASED ON LOWER SNOW ACCUM IN THE MORNING. ALSO ADJUSTED TOTALS ALONG AND W OF THE BLUE RIDGE BASED ON REPORTS. ALSO ADDED ISOLATED THUNDER TO AREAS S OF THE DC METRO. CONVECTION CURRENTLY OCCURRING OVER SE VA MAY ROTATE NWD INTO THE PIEDMONT AND SRN MD. ONE STRIKE WAS NOTED EARLIER OVER CULPEPER COUNTY...AND FORECAST SOUNDINGS INDICATE ELEVATED INSTABILITY. PREVIOUS DISCUSSION.... THE TRANSITION BETWEEN PHASES OF THIS INTENSE AND IMPACTFUL INCOMING SNOWSTORM IS FULLY UNDERWAY. THE INITIAL SFC LOW THAT DROPPED DOWN FROM THE NRN PLAINS INTO THE UPPER MIDWEST IS ABOUT TO BE PHASED-OUT. THE NEWER AND STRONGER LOW CURRENTLY OVER THE RALEIGH NC AREA WILL CREATE A SNOWY AND HAZARDOUS WEDNESDAY FOR MUCH OF THE MID-ATLC. THE NEXT SEVERAL HOURS WILL BE THE CRITICAL TRANSITION PERIOD AS THIS LOW INTENSIFIES AND ROTATES DUE NE TOWARD THE LOWER TIP OF THE DELMARVA PENINSULA AND DEVELOPS HEAVY SNOW BAND ACROSS THE NWRN QUADRANT OF THE LOW DURING THE DAYTIME HRS. THROUGH DAYBREAK... A REGIONAL VIEW OF THE RADAR RETURNS SHOWS THAT SNOW STILL AFFECTING MUCH OF THE UPPER MIDWEST...FROM CNTRL IN TO THE APLCNS...BUT THIS AREA OF PRECIP REGION WILL DISSIPATE IN THE NEXT FEW HRS. ONLY POCKETS OF HIGHER ELEVATION UPSLOPE SNOW WILL CONTINUE ALONG THE APLCN CHAIN. THE FIRST PHASE OF THE SYSTEM THAT BROUGHT LIGHT TO MODERATE SNOW OVER THE ENTIRE REGION IN JUST THE PAST FEW HOURS IS JUST THE START. ABOUT A HALF-FOOT OF SNOW HAS ALREADY FALLEN OVER THE HIGHER TERRAIN OF THE CNTRL APLCNS...TOWARD THE BLUE RIDGE. A FEW INCHES HAVE BEEN COMMON OVER THE SWRN QUADRANT OF THE CWA THRU 2-3AM. THE HEAVIER BANDS THAT BROUGHT THIS ACTIVITY ARE NOW SPREADING ACROSS THE DC/BALT AND THE PIEDMONT AREAS. THIS ACTIVITY WILL CREATE THE FIRST LAYER OF SNOW AND ALLOW FOR THE INITIAL BASE FOR ACCUMULATIONS FROM THE SECOND PHASE OF THE STORM. WINDS HAVE BEEN INTERMITTENTLY INCREASED...NORMALLY W/ SOME OF THE HEAVIER BANDS BUT THEN DROP BACK DOWN TO 5-10MPH. THESE LOWER WIND SPEEDS ARE ALLOWING FOR THE RELATIVELY HIGHER VISIBILITIES IN THE 1-2SM RANGE. THIS WILL CHANGE AS WINDS INCREASE AND SNOW INTENSITIES INCREASE. DETERMINISTIC NAM AND GFS RUNS STILL BULLISH ON QPF...SO THE CURRENT FORECAST IS A GOOD MIX OF NEAR TERM HI-RES GUIDANCE...INCLUDING LOCAL VERSION OF THE VARIOUS WRF MEMBERS AND ESPC THE HRRR WHICH HAS DONE WELL W/ INITIALIZING OVER THE FIRST PART OF THIS EVENT. DAYBREAK THROUGH MIDDAY... IF THEY HAVEN`T ALREADY BY DAYBREAK - CONDITIONS WILL DETERIORATE RAPIDLY ACROSS MOST - IF NOT ALL - OF THE CWA. LOCALIZED AREAS WILL RECEIVE BRIEF INTENSE SNOWFALL RATES OF 1-2 INCHES PER HR...POSSIBLY HIGHER. NOW THAT THE LOW IS ON THE DOORSTEP AND NEAR-TERM GUIDANCE HAS BEEN INITIALIZING W/ THIS DATA...SOME OF THE HI-RES MEMBERS HAVE STARTED TO DEPICT ONE LARGE ENCOMPASSING SNOW BAND - ORIENTED ALONG THE I-95 CORRIDOR BUT STRETCHING OVER THE ENTIRETY OF THE PIEDMONT/COASTAL COUNTIES...TAPERING OFF TOWARD THE BLUE RIDGE AND APLCNS. WITHIN THIS LARGER BAND WILL BE THE DYNAMIC HEAVIER BANDS W/ THE HIGHER INTENSITIES AND LOW VISIBILITIES. WINDS AROUND THIS SECTOR OF THE STORM WILL BE STRENGTHENING W/ SUST SPEEDS IN THE 15-25MPH RANGE AND PEAK GUSTS IN THE 30-40MPH RANGE. NEAR-WHITEOUT CONDITIONS ARE STILL IN QUESTION...IN TERMS OF AREA AND DURATION. THERE WILL BE BRIEF PERIODS OF NEAR-WHITEOUT CONDITIONS BUT AS FAR WIDESPREAD AND LONG-LIVED DURATIONS... CONFIDENCE IS LOWER. REGARDLESS...THE HEAVY-WET SNOW AND GUSTY WINDS WILL CREATE DANGEROUS AND NEAR-IMPOSSIBLE TRAVEL AT TIMES. MIDDAY THROUGH LATE TONIGHT... THE HEIGHT OF SNOWFALL RATES AND INTENSITIES ACROSS THE I-95 CORRIDOR...THE METRO AREAS AND THE VA/MD PIEDMONT IS EXPECTED TO BE FROM THE LATE MRNG INTO THE EARLY AFTN HRS. AT THIS TIME...THE LOW WILL BE MOVING AWAY FROM THE OCEAN CITY MD AREA...PULLING AWAY FROM THE COAST AND STARTING TO TAKE THE PRECIP ALONG WITH IT. SEVERAL ADDITIONAL INCHES OF SNOW WILL ACCUMULATE ACROSS THE REGION...BRINGING TOTALS TO LIKELY OVER A FOOT ACROSS MUCH OF THE SHEN VLY AND BETWEEN ONE-TO-TWO FT ALONG THE SURROUNDING RIDGELINES...JUST UNDER A FOOT ACROSS THE VA PIEDMONT AND JUST INTO N CNTRL MD...MORE OF A 6-12 INCH SPREAD ALONG THE I-95 CORRIDOR AND A RAIN/SNOW MIX ALONG THE WRN BAYSHORE COUNTIES AND SRN MD - THOUGH 4-8 INCH TOTAL STILL POSSIBLE AT THE TAIL END OF STORM SYSTEM LATER IN THE AFTN/EVE. A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER INTO THE EARLY MRNG HRS THU. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME. ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS SHOWING CLEAR TO PARTLY CLOUDY SKIES. NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY. CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR I-95. EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE. GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... A SNOWSTORM FOR MUCH OF THE AREA TODAY. THE PAST SEVERAL HRS HAS BEEN THE WARM-UP FOR THE MORE INTENSE VERSION LATER THIS MRNG AND AFTN. SOLID IFR CONDS ALREADY COVERING THE REGION W/ A FEW LIFR OBS SCATTERED ABOUT...UNDER THE HEAVIER SNOW BANDS. THE RESPONSIBLE SFC LOW IS STILL OVER ERN NC BUT WILL MOVE TOWARD THE NORFOLK VA AREA IN THE COMING HRS...INTENSIFY AND CREATE A STRONGER LOW LEVEL WIND FIELD BACK ACROSS MD/NRN VA. INTENSE SNOWFALL RATES...GUSTY WINDS AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND INTO THU. PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH PRESSURE THIS WEEKEND. && .MARINE... GALE FORCE WIND GUSTS WILL BECOME MORE COMMON HEADING INTO THE MRNG HRS TODAY...AS A SFC LOW MOVES FROM NRN NC TOWARD THE DELMARVA REGION. BREEZY E-NELY WINDS WILL BECOME INTENSE NLY WINDS WHILE THE LOW IS MOVING OFF THE COAST LATER THIS MRNG. SOLID GALE GUSTS WILL STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE GALE RANGE OVERNIGHT. WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK. && .HYDROLOGY... MODEL GUIDANCE REMAINS REMARKABLY CONSISTENT WITH A QPF BULLSEYE IN THE RAPPAHANNOCK BASIN. AROUND TWO INCHES OF LIQUID/LIQUID EQUIV PRECIPITATION IS LIKELY THROUGH MUCH OF THAT BASIN. IT LOOKS LIKE THE MAJORITY OF THAT WILL WIND UP BEING FROM SNOW ESPECIALLY IN THE UPPER PART. IN ADDITION...SFC TEMPS AND SOIL TEMPS ARE AND WILL REMAIN ABOVE FREEZING OUTSIDE THE HIGHER ELEVATIONS...SO THERE WILL BE SOME SOIL INFILTRATION INITIALLY FROM RAIN...LIQUID FROM SNOW...OR BOTH. THEN WE HAVE TO LOOK AT HOW QUICKLY THE SNOW MELTS...AND HOW LONG IT TAKES TO START MELTING THE MOUNTAIN SNOWS TO ADD TO THE PICTURE. THE MOST LIKELY SCENARIO IS FOR THERE TO BE A GRADUAL MELT...WHICH WOULD NOT POSE MUCH OF A FLOOD THREAT...BUT THE AFOREMENTIONED UNCERTAINTIES LEND THEMSELVES TO KEEPING AN EYE ON THE SITUATION THROUGH THE END OF THE WEEK. && .TIDES/COASTAL FLOODING... ANOMALIES HAVE TURNED POSITIVE...CLOSE TO 1 FT ABOVE NORMAL AT 3 AM ALONG THE WESTERN SHORE OF THE BAY. WITH EASTERLY FLOW PERSISTING THIS MORNING...ANOMALIES WILL CONTINUE TO CLIMB POSSIBLY ON THE ORDER OF 1.5 TO 2 FT ABOVE NORMAL. THIS WILL PRODUCE MINOR TIDAL FLOODING ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY UP THROUGH AT LEAST ANNE ARUNDEL COUNTY...AND CONFIDENCE IS INCREASING OF THE MINOR THRESHOLD BEING REACHED TOWARD BALTIMORE DURING HIGH TIDE. CONFIDENCE DECREASES NORTH OF HERE WITH AN EAST WIND BECOMING NORTHEAST BY HIGH TIDE TIME. SAME GOES FOR THE UPPER TIDAL POTOMAC...SO WILL REFRAIN FROM ADVISORY IN THESE AREAS DO TO LOWER CONFIDENCE BUT WILL NEED TO BE WATCHED. LATER THIS AFTERNOON AND EVENING WHEN WINDS DO TURN NORTHERLY...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER IN THE UPPER BAY. FORECAST MODEL SHOWS A LITTLE WATER TRAPPING IN THE LOWERMOST TIDAL POTOMAC THAT KEEPS LEVELS ELEVATED FOR THE WEDNESDAY EVENING CYCLE THERE. WILL HAVE TO KEEP AN EYE ON THAT. WINDS TURN OUT OF THE NORTHWEST AFTER THAT...WHICH SHOULD MAKE EVERYTHING DROP SIGNIFICANTLY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001. MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501- 502. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007- 009>011-013-014-016>018. COASTAL FLOOD ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR MDZ014-017-018. COASTAL FLOOD ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MDZ011. VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031- 503-504. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040- 042-050>057-501-502. WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053- 055-501>506. MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535- 536. GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536. && $$ SYNOPSIS...BPP/GMS NEAR TERM...GMS/KCS SHORT TERM...BPP LONG TERM...JRK AVIATION...JRK/BPP/GMS MARINE...JRK/BPP/GMS HYDROLOGY... TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
832 AM EST WED MAR 6 2013 .SYNOPSIS... STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AT 0830AM...QUICK UPDATE MADE TO MORNING FCST BASED ON CURRENT RADAR/OBS. RAIN/SNOW LINE IS JUST TO SOUTHEAST OF A LINE FROM BWI/ADW/DCA. SOUTHEAST OF THIS LINE...MOSTLY RAIN IS FALLING WITH SURFACE TEMPS IN UPPER 30S...TO EVEN LOW 40S OVER SRN MD. LOW PRESSURE IS NOW OVER THE NORFOLK METRO AREA...WITH AN EASTERLY WIND ADVECTING MARINE AIR OVER SRN MD. AS THE BOTH THE SURFACE AND UPPER LOW MOVE TOWARDS THE NORTH DURING THE DAY TODAY...WINDS ARE EXPECTED TO BECOME MORE NORTHERLY AND DRAW IN COOLER AIR. FOR THIS REASON...STILL EXPECTING A CHANGEOVER TO SNOW ALONG AND EAST OF THE I-95 CORRIDOR. ADJUSTED SNOWFALL TOTALS DOWN S AND E OF BWI/DCA BASED ON LOWER SNOW ACCUM IN THE MORNING. ALSO ADJUSTED TOTALS ALONG AND W OF THE BLUE RIDGE BASED ON REPORTS. PREVIOUS DISCUSSION.... THE TRANSITION BETWEEN PHASES OF THIS INTENSE AND IMPACTFUL INCOMING SNOWSTORM IS FULLY UNDERWAY. THE INITIAL SFC LOW THAT DROPPED DOWN FROM THE NRN PLAINS INTO THE UPPER MIDWEST IS ABOUT TO BE PHASED-OUT. THE NEWER AND STRONGER LOW CURRENTLY OVER THE RALEIGH NC AREA WILL CREATE A SNOWY AND HAZARDOUS WEDNESDAY FOR MUCH OF THE MID-ATLC. THE NEXT SEVERAL HOURS WILL BE THE CRITICAL TRANSITION PERIOD AS THIS LOW INTENSIFIES AND ROTATES DUE NE TOWARD THE LOWER TIP OF THE DELMARVA PENINSULA AND DEVELOPS HEAVY SNOW BAND ACROSS THE NWRN QUADRANT OF THE LOW DURING THE DAYTIME HRS. THROUGH DAYBREAK... A REGIONAL VIEW OF THE RADAR RETURNS SHOWS THAT SNOW STILL AFFECTING MUCH OF THE UPPER MIDWEST...FROM CNTRL IN TO THE APLCNS...BUT THIS AREA OF PRECIP REGION WILL DISSIPATE IN THE NEXT FEW HRS. ONLY POCKETS OF HIGHER ELEVATION UPSLOPE SNOW WILL CONTINUE ALONG THE APLCN CHAIN. THE FIRST PHASE OF THE SYSTEM THAT BROUGHT LIGHT TO MODERATE SNOW OVER THE ENTIRE REGION IN JUST THE PAST FEW HOURS IS JUST THE START. ABOUT A HALF-FOOT OF SNOW HAS ALREADY FALLEN OVER THE HIGHER TERRAIN OF THE CNTRL APLCNS...TOWARD THE BLUE RIDGE. A FEW INCHES HAVE BEEN COMMON OVER THE SWRN QUADRANT OF THE CWA THRU 2-3AM. THE HEAVIER BANDS THAT BROUGHT THIS ACTIVITY ARE NOW SPREADING ACROSS THE DC/BALT AND THE PIEDMONT AREAS. THIS ACTIVITY WILL CREATE THE FIRST LAYER OF SNOW AND ALLOW FOR THE INITIAL BASE FOR ACCUMULATIONS FROM THE SECOND PHASE OF THE STORM. WINDS HAVE BEEN INTERMITTENTLY INCREASED...NORMALLY W/ SOME OF THE HEAVIER BANDS BUT THEN DROP BACK DOWN TO 5-10MPH. THESE LOWER WIND SPEEDS ARE ALLOWING FOR THE RELATIVELY HIGHER VISIBILITIES IN THE 1-2SM RANGE. THIS WILL CHANGE AS WINDS INCREASE AND SNOW INTENSITIES INCREASE. DETERMINISTIC NAM AND GFS RUNS STILL BULLISH ON QPF...SO THE CURRENT FORECAST IS A GOOD MIX OF NEAR TERM HI-RES GUIDANCE...INCLUDING LOCAL VERSION OF THE VARIOUS WRF MEMBERS AND ESPC THE HRRR WHICH HAS DONE WELL W/ INITIALIZING OVER THE FIRST PART OF THIS EVENT. DAYBREAK THROUGH MIDDAY... IF THEY HAVEN`T ALREADY BY DAYBREAK - CONDITIONS WILL DETERIORATE RAPIDLY ACROSS MOST - IF NOT ALL - OF THE CWA. LOCALIZED AREAS WILL RECEIVE BRIEF INTENSE SNOWFALL RATES OF 1-2 INCHES PER HR...POSSIBLY HIGHER. NOW THAT THE LOW IS ON THE DOORSTEP AND NEAR-TERM GUIDANCE HAS BEEN INITIALIZING W/ THIS DATA...SOME OF THE HI-RES MEMBERS HAVE STARTED TO DEPICT ONE LARGE ENCOMPASSING SNOW BAND - ORIENTED ALONG THE I-95 CORRIDOR BUT STRETCHING OVER THE ENTIRETY OF THE PIEDMONT/COASTAL COUNTIES...TAPERING OFF TOWARD THE BLUE RIDGE AND APLCNS. WITHIN THIS LARGER BAND WILL BE THE DYNAMIC HEAVIER BANDS W/ THE HIGHER INTENSITIES AND LOW VISIBILITIES. WINDS AROUND THIS SECTOR OF THE STORM WILL BE STRENGTHENING W/ SUST SPEEDS IN THE 15-25MPH RANGE AND PEAK GUSTS IN THE 30-40MPH RANGE. NEAR-WHITEOUT CONDITIONS ARE STILL IN QUESTION...IN TERMS OF AREA AND DURATION. THERE WILL BE BRIEF PERIODS OF NEAR-WHITEOUT CONDITIONS BUT AS FAR WIDESPREAD AND LONG-LIVED DURATIONS... CONFIDENCE IS LOWER. REGARDLESS...THE HEAVY-WET SNOW AND GUSTY WINDS WILL CREATE DANGEROUS AND NEAR-IMPOSSIBLE TRAVEL AT TIMES. MIDDAY THROUGH LATE TONIGHT... THE HEIGHT OF SNOWFALL RATES AND INTENSITIES ACROSS THE I-95 CORRIDOR...THE METRO AREAS AND THE VA/MD PIEDMONT IS EXPECTED TO BE FROM THE LATE MRNG INTO THE EARLY AFTN HRS. AT THIS TIME...THE LOW WILL BE MOVING AWAY FROM THE OCEAN CITY MD AREA...PULLING AWAY FROM THE COAST AND STARTING TO TAKE THE PRECIP ALONG WITH IT. SEVERAL ADDITIONAL INCHES OF SNOW WILL ACCUMULATE ACROSS THE REGION...BRINGING TOTALS TO LIKELY OVER A FOOT ACROSS MUCH OF THE SHEN VLY AND BETWEEN ONE-TO-TWO FT ALONG THE SURROUNDING RIDGELINES...JUST UNDER A FOOT ACROSS THE VA PIEDMONT AND JUST INTO N CNTRL MD...MORE OF A 6-12 INCH SPREAD ALONG THE I-95 CORRIDOR AND A RAIN/SNOW MIX ALONG THE WRN BAYSHORE COUNTIES AND SRN MD - THOUGH 4-8 INCH TOTAL STILL POSSIBLE AT THE TAIL END OF STORM SYSTEM LATER IN THE AFTN/EVE. A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER INTO THE EARLY MRNG HRS THU. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME. ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS SHOWING CLEAR TO PARTLY CLOUDY SKIES. NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY. CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR I-95. EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE. GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE. && .AVIATION /14Z WEDNESDAY THROUGH SUNDAY/... A SNOWSTORM FOR MUCH OF THE AREA TODAY. THE PAST SEVERAL HRS HAS BEEN THE WARM-UP FOR THE MORE INTENSE VERSION LATER THIS MRNG AND AFTN. SOLID IFR CONDS ALREADY COVERING THE REGION W/ A FEW LIFR OBS SCATTERED ABOUT...UNDER THE HEAVIER SNOW BANDS. THE RESPONSIBLE SFC LOW IS STILL OVER ERN NC BUT WILL MOVE TOWARD THE NORFOLK VA AREA IN THE COMING HRS...INTENSIFY AND CREATE A STRONGER LOW LEVEL WIND FIELD BACK ACROSS MD/NRN VA. INTENSE SNOWFALL RATES...GUSTY WINDS AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND INTO THU. PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH PRESSURE THIS WEEKEND. && .MARINE... GALE FORCE WIND GUSTS WILL BECOME MORE COMMON HEADING INTO THE MRNG HRS TODAY...AS A SFC LOW MOVES FROM NRN NC TOWARD THE DELMARVA REGION. BREEZY E-NELY WINDS WILL BECOME INTENSE NLY WINDS WHILE THE LOW IS MOVING OFF THE COAST LATER THIS MRNG. SOLID GALE GUSTS WILL STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE GALE RANGE OVERNIGHT. WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK. && .HYDROLOGY... MODEL GUIDANCE REMAINS REMARKABLY CONSISTENT WITH A QPF BULLSEYE IN THE RAPPAHANNOCK BASIN. AROUND TWO INCHES OF LIQUID/LIQUID EQUIV PRECIPITATION IS LIKELY THROUGH MUCH OF THAT BASIN. IT LOOKS LIKE THE MAJORITY OF THAT WILL WIND UP BEING FROM SNOW ESPECIALLY IN THE UPPER PART. IN ADDITION...SFC TEMPS AND SOIL TEMPS ARE AND WILL REMAIN ABOVE FREEZING OUTSIDE THE HIGHER ELEVATIONS...SO THERE WILL BE SOME SOIL INFILTRATION INITIALLY FROM RAIN...LIQUID FROM SNOW...OR BOTH. THEN WE HAVE TO LOOK AT HOW QUICKLY THE SNOW MELTS...AND HOW LONG IT TAKES TO START MELTING THE MOUNTAIN SNOWS TO ADD TO THE PICTURE. THE MOST LIKELY SCENARIO IS FOR THERE TO BE A GRADUAL MELT...WHICH WOULD NOT POSE MUCH OF A FLOOD THREAT...BUT THE AFOREMENTIONED UNCERTAINTIES LEND THEMSELVES TO KEEPING AN EYE ON THE SITUATION THROUGH THE END OF THE WEEK. && .TIDES/COASTAL FLOODING... ANOMALIES HAVE TURNED POSITIVE...CLOSE TO 1 FT ABOVE NORMAL AT 3 AM ALONG THE WESTERN SHORE OF THE BAY. WITH EASTERLY FLOW PERSISTING THIS MORNING...ANOMALIES WILL CONTINUE TO CLIMB POSSIBLY ON THE ORDER OF 1.5 TO 2 FT ABOVE NORMAL. THIS WILL PRODUCE MINOR TIDAL FLOODING ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY UP THROUGH AT LEAST ANNE ARUNDEL COUNTY...AND CONFIDENCE IS INCREASING OF THE MINOR THRESHOLD BEING REACHED TOWARD BALTIMORE DURING HIGH TIDE. CONFIDENCE DECREASES NORTH OF HERE WITH AN EAST WIND BECOMING NORTHEAST BY HIGH TIDE TIME. SAME GOES FOR THE UPPER TIDAL POTOMAC...SO WILL REFRAIN FROM ADVISORY IN THESE AREAS DO TO LOWER CONFIDENCE BUT WILL NEED TO BE WATCHED. LATER THIS AFTERNOON AND EVENING WHEN WINDS DO TURN NORTHERLY...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER IN THE UPPER BAY. FORECAST MODEL SHOWS A LITTLE WATER TRAPPING IN THE LOWERMOST TIDAL POTOMAC THAT KEEPS LEVELS ELEVATED FOR THE WEDNESDAY EVENING CYCLE THERE. WILL HAVE TO KEEP AN EYE ON THAT. WINDS TURN OUT OF THE NORTHWEST AFTER THAT...WHICH SHOULD MAKE EVERYTHING DROP SIGNIFICANTLY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001. MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501- 502. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007- 009>011-013-014-016>018. COASTAL FLOOD ADVISORY UNTIL 2 PM EST THIS AFTERNOON FOR MDZ014-017-018. COASTAL FLOOD ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR MDZ011. VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031- 503-504. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040- 042-050>057-501-502. WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053- 055-501>506. MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535- 536. GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536. && $$ SYNOPSIS...BPP/GMS NEAR TERM...GMS/KCS SHORT TERM...BPP LONG TERM...JRK AVIATION...JRK/BPP/GMS MARINE...JRK/BPP/GMS HYDROLOGY... TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS BALTIMORE MD/WASHINGTON DC
400 AM EST WED MAR 6 2013 .SYNOPSIS... STRONG LOW PRESSURE WILL IMPACT THE AREA THROUGH TONIGHT. THE LOW WILL MOVE AWAY FROM THE AREA THURSDAY. HIGH PRESSURE WILL BUILD OVERHEAD LATE IN THE WEEK AND PERSIST THROUGH THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... THE TRANSITION BETWEEN PHASES OF THIS INTENSE AND IMPACTFUL INCOMING SNOWSTORM IS FULLY UNDERWAY. THE INITIAL SFC LOW THAT DROPPED DOWN FROM THE NRN PLAINS INTO THE UPPER MIDWEST IS ABOUT TO BE PHASED-OUT. THE NEWER AND STRONGER LOW CURRENTLY OVER THE RALEIGH NC AREA WILL CREATE A SNOWY AND HAZARDOUS WEDNESDAY FOR MUCH OF THE MID-ATLC. THE NEXT SEVERAL HOURS WILL BE THE CRITICAL TRANSITION PERIOD AS THIS LOW INTENSIFIES AND ROTATES DUE NE TOWARD THE LOWER TIP OF THE DELMARVA PENINSULA AND DEVELOPS HEAVY SNOW BAND ACROSS THE NWRN QUADRANT OF THE LOW DURING THE DAYTIME HRS. THROUGH DAYBREAK... A REGIONAL VIEW OF THE RADAR RETURNS SHOWS THAT SNOW STILL AFFECTING MUCH OF THE UPPER MIDWEST...FROM CNTRL IN TO THE APLCNS...BUT THIS AREA OF PRECIP REGION WILL DISSIPATE IN THE NEXT FEW HRS. ONLY POCKETS OF HIGHER ELEVATION UPSLOPE SNOW WILL CONTINUE ALONG THE APLCN CHAIN. THE FIRST PHASE OF THE SYSTEM THAT BROUGHT LIGHT TO MODERATE SNOW OVER THE ENTIRE REGION IN JUST THE PAST FEW HOURS IS JUST THE START. ABOUT A HALF-FOOT OF SNOW HAS ALREADY FALLEN OVER THE HIGHER TERRAIN OF THE CNTRL APLCNS...TOWARD THE BLUE RIDGE. A FEW INCHES HAVE BEEN COMMON OVER THE SWRN QUADRANT OF THE CWA THRU 2-3AM. THE HEAVIER BANDS THAT BROUGHT THIS ACTIVITY ARE NOW SPREADING ACROSS THE DC/BALT AND THE PIEDMONT AREAS. THIS ACTIVITY WILL CREATE THE FIRST LAYER OF SNOW AND ALLOW FOR THE INITIAL BASE FOR ACCUMULATIONS FROM THE SECOND PHASE OF THE STORM. WINDS HAVE BEEN INTERMITTENTLY INCREASED...NORMALLY W/ SOME OF THE HEAVIER BANDS BUT THEN DROP BACK DOWN TO 5-10MPH. THESE LOWER WIND SPEEDS ARE ALLOWING FOR THE RELATIVELY HIGHER VISIBILITIES IN THE 1-2SM RANGE. THIS WILL CHANGE AS WINDS INCREASE AND SNOW INTENSITIES INCREASE. DETERMINISTIC NAM AND GFS RUNS STILL BULLISH ON QPF...SO THE CURRENT FORECAST IS A GOOD MIX OF NEAR TERM HI-RES GUIDANCE...INCLUDING LOCAL VERSION OF THE VARIOUS WRF MEMBERS AND ESPC THE HRRR WHICH HAS DONE WELL W/ INITIALIZING OVER THE FIRST PART OF THIS EVENT. DAYBREAK THROUGH MIDDAY... IF THEY HAVEN`T ALREADY BY DAYBREAK - CONDITIONS WILL DETERIORATE RAPIDLY ACROSS MOST - IF NOT ALL - OF THE CWA. LOCALIZED AREAS WILL RECEIVE BRIEF INTENSE SNOWFALL RATES OF 1-2 INCHES PER HR...POSSIBLY HIGHER. NOW THAT THE LOW IS ON THE DOORSTEP AND NEAR-TERM GUIDANCE HAS BEEN INITIALIZING W/ THIS DATA...SOME OF THE HI-RES MEMBERS HAVE STARTED TO DEPICT ONE LARGE ENCOMPASSING SNOW BAND - ORIENTED ALONG THE I-95 CORRIDOR BUT STRETCHING OVER THE ENTIRETY OF THE PIEDMONT/COASTAL COUNTIES...TAPERING OFF TOWARD THE BLUE RIDGE AND APLCNS. WITHIN THIS LARGER BAND WILL BE THE DYNAMIC HEAVIER BANDS W/ THE HIGHER INTENSITIES AND LOW VISIBILITIES. WINDS AROUND THIS SECTOR OF THE STORM WILL BE STRENGTHENING W/ SUST SPEEDS IN THE 15-25MPH RANGE AND PEAK GUSTS IN THE 30-40MPH RANGE. NEAR-WHITEOUT CONDITIONS ARE STILL IN QUESTION...IN TERMS OF AREA AND DURATION. THERE WILL BE BRIEF PERIODS OF NEAR-WHITEOUT CONDITIONS BUT AS FAR WIDESPREAD AND LONG-LIVED DURATIONS... CONFIDENCE IS LOWER. REGARDLESS...THE HEAVY-WET SNOW AND GUSTY WINDS WILL CREATE DANGEROUS AND NEAR-IMPOSSIBLE TRAVEL AT TIMES. MIDDAY THROUGH LATE TONIGHT... THE HEIGHT OF SNOWFALL RATES AND INTENSITIES ACROSS THE I-95 CORRIDOR...THE METRO AREAS AND THE VA/MD PIEDMONT IS EXPECTED TO BE FROM THE LATE MRNG INTO THE EARLY AFTN HRS. AT THIS TIME...THE LOW WILL BE MOVING AWAY FROM THE OCEAN CITY MD AREA...PULLING AWAY FROM THE COAST AND STARTING TO TAKE THE PRECIP ALONG WITH IT. SEVERAL ADDITIONAL INCHES OF SNOW WILL ACCUMULATE ACROSS THE REGION...BRINGING TOTALS TO LIKELY OVER A FOOT ACROSS MUCH OF THE SHEN VLY AND BETWEEN ONE-TO-TWO FT ALONG THE SURROUNDING RIDGELINES...JUST UNDER A FOOT ACROSS THE VA PIEDMONT AND JUST INTO N CNTRL MD...MORE OF A 6-12 INCH SPREAD ALONG THE I-95 CORRIDOR AND A RAIN/SNOW MIX ALONG THE WRN BAYSHORE COUNTIES AND SRN MD - THOUGH 4-8 INCH TOTAL STILL POSSIBLE AT THE TAIL END OF STORM SYSTEM LATER IN THE AFTN/EVE. A RAPID DECREASE IN SNOW INTENSITIES WILL OCCUR TOWARD THE MIDDLE/LATE EVE HRS FROM WEST-TO-EAST AS THE LOW ACCELERATES OFF THE COAST AND DISSIPATES THE LARGER SNOW BAND OVER THE REGION. ONLY FLURRIES AND RESIDUAL LIGHT POCKETS OF SNOW CONTINUE LATE THIS EVE BUT ALSO DISSIPATE INTO THE OVERNIGHT HRS. AS CONDITIONS DRY OUT...WINDS WILL REMAIN. TEMPS WON`T DROP TOO MUCH FURTHER BELOW FREEZING BUT WILL CHILLS WILL...AS A DRIER BITING NW WIND TAKES OVER INTO THE EARLY MRNG HRS THU. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... COASTAL LOW WILL BE WELL OFFSHORE THURSDAY MORNING...BUT IS FORECAST TO MOVE LITTLE AND MEANDER ACROSS THE WESTERN ATLANTIC THROUGH FRIDAY. THIS WILL KEEP THE CWA IN A NORTHERLY FLOW DURING THIS TIME. ANY LINGERING SNOWFALL ASSOCIATED WITH WRAP AROUND/DEFORMATION SHOULD MOVE EAST OF THE BAY THURSDAY MORNING...LEAVING A DRY FORECAST FOR THE REST OF THE DAY SAVE FOR SOME SNOW SHOWERS ON THE WESTERN SLOPES. IN FACT...PARTIAL SUNSHINE MAY EVEN BE SEEN IN THE AFTERNOON WHICH WILL HELP TO MELT SOME SNOW. BUT WITH SNOWPACK...OPTED REMAIN BELOW MOS GUIDANCE FOR MAXIMA. KEPT THE SAME IDEA FOR MINIMA THURSDAY NIGHT...ESPECIALLY WITH MODELS SHOWING CLEAR TO PARTLY CLOUDY SKIES. NAM IS MORE AGGRESSIVE TRYING TO WRAP AROUND MORE CLOUDS AND EVEN SOME PRECIP ACROSS THE NORTHEAST PORTION OF THE CWA FRIDAY. CONFIDENCE IS LOW ON PRECIP BEING ABLE TO WRAP BACK THIS FAR WEST SO KEPT DRY FORECAST...BUT DID INCLUDE MORE CLOUDS. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE LOW WILL GRADUALLY PULL AWAY FROM THE AREA THIS WEEKEND AS SFC HIPRES/UPPER RIDGE BUILDS ACROSS THE ERN CONUS. A MODERATING TREND CAN BE EXPECTED THROUGH ERY NEXT WEEK. MAX TEMPS WILL BE IN 40S WHERE A DEEPER SNOW PACK PERSISTS AND POSSIBLY 50S FARTHER EAST NEAR I-95. EXTENDED-RANGE GUIDANCE HAS TRENDED SLOWER WITH THE NEXT LOPRES SYSTEM AND COLD FRONT...WHICH NOW LOOKS TO APPROACH LATE MON OR TUE. GIVEN LATEST TRACK OF SFC LOW...DEEP WARM SLY FLOW IN PRE-FRONTAL WARM SECTOR MAY LEAD TO SIGNIFICANT MELTING OF SNOW PACK AS HIGHS COULD POTENTIALLY REACH THE UPPER 40S AND 50S MON/TUE. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... A SNOWSTORM FOR MUCH OF THE AREA TODAY. THE PAST SEVERAL HRS HAS BEEN THE WARM-UP FOR THE MORE INTENSE VERSION LATER THIS MRNG AND AFTN. SOLID IFR CONDS ALREADY COVERING THE REGION W/ A FEW LIFR OBS SCATTERED ABOUT...UNDER THE HEAVIER SNOW BANDS. THE RESPONSIBLE SFC LOW IS STILL OVER ERN NC BUT WILL MOVE TOWARD THE NORFOLK VA AREA IN THE COMING HRS...INTENSIFY AND CREATE A STRONGER LOW LEVEL WIND FIELD BACK ACROSS MD/NRN VA. INTENSE SNOWFALL RATES...GUSTY WINDS AND REDUCED VSBYS WILL BE CENTERED OVER THE I-95 CORRIDOR AND BACK TOWARD THE BLUE RIDGE BETWEEN THROUGH 20Z...TAPERING OFF TOWARD THE END OF THAT PERIOD. SNOW WILL BEGIN TO DISSIPATE DURING THE EVE HRS...BUT WINDS WILL REMAIN BREEZY OUT OF THE NW ALL NIGHT AND INTO THU. PRECIP SHOULD SHUT OFF BY EARLY THURSDAY MORNING...WITH A RETURN TO VFR CONDITIONS FOR THURSDAY. MAIN IMPACT WILL BE FROM GUSTY NORTHWEST WINDS WHICH MAY LINGER INTO FRIDAY. QUIET WITH HIGH PRESSURE THIS WEEKEND. && .MARINE... GALE FORCE WIND GUSTS WILL BECOME MORE COMMON HEADING INTO THE MRNG HRS TODAY...AS A SFC LOW MOVES FROM NRN NC TOWARD THE DELMARVA REGION. BREEZY E-NELY WINDS WILL BECOME INTENSE NLY WINDS WHILE THE LOW IS MOVING OFF THE COAST LATER THIS MRNG. SOLID GALE GUSTS WILL STREAM DOWN THE MAIN CHANNEL OF THE BAY AND TP RVR. THIS WILL CONTINUE INTO THE LATE NIGHT HRS...AND WINDS WILL STILL GUST IN THE GALE RANGE OVERNIGHT. WINDS BECOME NORTHWEST BY THURSDAY...AND WITH FORECAST GRADIENT HAVE EXTEND GALES FOR MUCH OF THE MARINE AREA INTO THURSDAY. SCA CONDITIONS ARE LIKELY TO LINGER THROUGH THE END OF THE WEEK. && .HYDROLOGY... MODEL GUIDANCE REMAINS REMARKABLY CONSISTENT WITH A QPF BULLSEYE IN THE RAPPAHANNOCK BASIN. AROUND TWO INCHES OF LIQUID/LIQUID EQUIV PRECIPITATION IS LIKELY THROUGH MUCH OF THAT BASIN. IT LOOKS LIKE THE MAJORITY OF THAT WILL WIND UP BEING FROM SNOW ESPECIALLY IN THE UPPER PART. IN ADDITION...SFC TEMPS AND SOIL TEMPS ARE AND WILL REMAIN ABOVE FREEZING OUTSIDE THE HIGHER ELEVATIONS...SO THERE WILL BE SOME SOIL INFILTRATION INITIALLY FROM RAIN...LIQUID FROM SNOW...OR BOTH. THEN WE HAVE TO LOOK AT HOW QUICKLY THE SNOW MELTS...AND HOW LONG IT TAKES TO START MELTING THE MOUNTAIN SNOWS TO ADD TO THE PICTURE. THE MOST LIKELY SCENARIO IS FOR THERE TO BE A GRADUAL MELT...WHICH WOULD NOT POSE MUCH OF A FLOOD THREAT...BUT THE AFOREMENTIONED UNCERTAINTIES LEND THEMSELVES TO KEEPING AN EYE ON THE SITUATION THROUGH THE END OF THE WEEK. && .TIDES/COASTAL FLOODING... ANOMALIES HAVE TURNED POSITIVE...CLOSE TO 1 FT ABOVE NORMAL AT 3 AM ALONG THE WESTERN SHORE OF THE BAY. WITH EASTERLY FLOW PERSISTING THIS MORNING...ANOMALIES WILL CONTINUE TO CLIMB POSSIBLY ON THE ORDER OF 1.5 TO 2 FT ABOVE NORMAL. THIS WILL PRODUCE MINOR TIDAL FLOODING ALONG THE WESTERN SHORE OF THE CHESAPEAKE BAY UP THROUGH AT LEAST ANNE ARUNDEL COUNTY...AND CONFIDENCE IS INCREASING OF THE MINOR THRESHOLD BEING REACHED TOWARD BALTIMORE DURING HIGH TIDE. CONFIDENCE DECREASES NORTH OF HERE WITH AN EAST WIND BECOMING NORTHEAST BY HIGH TIDE TIME. SAME GOES FOR THE UPPER TIDAL POTOMAC...SO WILL REFRAIN FROM ADVISORY IN THESE AREAS DO TO LOWER CONFIDENCE BUT WILL NEED TO BE WATCHED. LATER THIS AFTERNOON AND EVENING WHEN WINDS DO TURN NORTHERLY...THERE WILL BE A SHARP BLOWOUT TIDE...PERHAPS COMPLETELY DAMPENING OUT THE WEDNESDAY NIGHT HIGH TIDE ALTOGETHER IN THE UPPER BAY. FORECAST MODEL SHOWS A LITTLE WATER TRAPPING IN THE LOWERMOST TIDAL POTOMAC THAT KEEPS LEVELS ELEVATED FOR THE WEDNESDAY EVENING CYCLE THERE. WILL HAVE TO KEEP AN EYE ON THAT. WINDS TURN OUT OF THE NORTHWEST AFTER THAT...WHICH SHOULD MAKE EVERYTHING DROP SIGNIFICANTLY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR DCZ001. MD...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR MDZ003-501- 502. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR MDZ004>007- 009>011-013-014-016>018. COASTAL FLOOD ADVISORY FROM 7 AM THIS MORNING TO 2 PM EST THIS AFTERNOON FOR MDZ014-017-018. COASTAL FLOOD ADVISORY FROM 11 AM THIS MORNING TO 4 PM EST THIS AFTERNOON FOR MDZ011. VA...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR VAZ025>031- 503-504. WINTER STORM WARNING UNTIL 3 AM EST THURSDAY FOR VAZ036>040- 042-050>057-501-502. WV...WINTER STORM WARNING UNTIL MIDNIGHT EST TONIGHT FOR WVZ050>053- 055-501>506. MARINE...GALE WARNING UNTIL 6 PM EST THURSDAY FOR ANZ530>534-537>543. SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EST THURSDAY FOR ANZ535- 536. GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ535-536. && $$ SYNOPSIS...BPP/GMS NEAR TERM...GMS SHORT TERM...BPP LONG TERM...JRK AVIATION...JRK/BPP/GMS MARINE...JRK/BPP/GMS HYDROLOGY...BPP/JE TIDES/COASTAL FLOODING...BPP/JE
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1242 PM EST WED MAR 6 2013 .UPDATE... ISSUED AT 1151 AM EST WED MAR 6 2013 ONLY MINOR ADJUSTMENTS TO THE GOING FORECAST...MOST OF WHICH WERE DONE EARLIER TO EXPAND THE SOUTHERN EXTENT OF THE SNOWFALL TO SHOW A PERIOD OF SNOW MOVING EAST THROUGH THE AREA. THIS SNOW IS ASSOCIATED WITH THE SHORTWAVE SEEN ON WV IMAGERY MOVING ACROSS WESTERN LAKE SUPERIOR AND INTO WESTERN UPPER MICHIGAN AND AN AREA OF MID LEVEL FGEN AND Q-VECTOR CONVERGENCE. OVER THE LAST HOUR OR TWO...THE SNOW HAS INCREASED IN INTENSITY ON RADAR AND WE HAVE SEEN 1.1 INCHES THUS FAR AT THE OFFICE. THUS...TWEAKED UP SNOWFALL AMOUNTS OVER THE NORTH HALF OF THE EASTERN CWA TO AN ADDITIONAL INCH THROUGH THE AFTERNOON. DRY AIR SURGING IN BEHIND THE SHORTWAVE HAS BROUGHT AN END TO THE SYNOPTIC SNOW OUT WEST AND VISIBLE SATELLITE SHOWS THAT LAKE EFFECT SNOW BANDS HAVE DEVELOPED OVER THE WESTERN LAKE. WILL HOLD ONTO SCATTERED SNOW SHOWERS OVER THE WEST THROUGH THE AFTERNOON AND HAVE MADE AN ADJUSTMENT UP TO POPS /TO HIGH END SCATTERED/ OVER THE KEWEENAW THIS EVENING...AS COLDER AIR ROTATES SOUTHEAST BEHIND THE SHORTWAVE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 534 AM EST WED MAR 6 2013 INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH. TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH. FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS AROUND 600MB. STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH. THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING. MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM GUIDANCE. MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI BORDER. OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN. ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA. TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS DROP BELOW ZERO IN A FEW SPOTS WELL INLAND. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 534 AM EST WED MAR 6 2013 HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS. UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH HIGHS GENERALLY IN THE LOWER TO MID 30S. BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST ...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT NIGHT. HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW. MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1241 PM EST WED MAR 6 2013 SHORTWAVE THAT BROUGHT THE SNOW TO ALL THREE TAF SITES THIS MORNING SHOULD CONTINUE EAST THIS AFTERNOON AND BRING AN END TO THE MODERATE SNOW AT KSAW WITHIN THE NEXT HOUR OR TWO. FOCUS THEN TURNS TO LAKE EFFECT SNOW WITH THE NORTHWEST WINDS...ESPECIALLY FOR KCMX. WITH COLDER AIR MOVING SOUTHEAST THROUGH THIS EVENING...EXPECT LIGHT LAKE EFFECT TO AFFECT KCMX/KIWD THROUGH THE AFTERNOON WITH MVFR CEILINGS. AS A POCKET OF COLDER AIR MOVES OVER THE KEWEENAW THIS EVENING...HAVE TRIED TO SHOW A PERIOD OF STRONGER SNOW SHOWERS BEFORE DRIER AIR FROM AN APPROACHING HIGH PRESSURE MOVES IN OVERNIGHT. THIS SHOULD BRING AN END TO THE SNOW TONIGHT AND THEN EVENTUALLY DIMINISH THE CLOUDS TOMORROW MORNING/AFTERNOON. AT KSAW...HELD ONTO THE MVFR CEILINGS THROUGH MUCH OF THE NIGHT...BUT THERE IS THE POTENTIAL THEY COULD SCATTER OUT OR GO TO VFR WITH THE LIGHT DOWNSLOPING NORTHWEST FLOW. DEFINITELY FOLLOWED THAT TREND FOR TOMORROW MORNING...ALTHOUGH THERE COULD BE DIURNAL CU REDEVELOPING TOWARDS THE END OF THE TAF PERIOD. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 534 AM EST WED MAR 6 2013 A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS. EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY AFTERNOON AND EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...SRF SHORT TERM...TK LONG TERM...VOSS AVIATION...SRF MARINE...TK
AREA FORECAST DISCUSSION...UPDATED
NWS MARQUETTE MI
1152 AM EST WED MAR 6 2013 .UPDATE... ISSUED AT 1151 AM EST WED MAR 6 2013 ONLY MINOR ADJUSTMENTS TO THE GOING FORECAST...MOST OF WHICH WERE DONE EARLIER TO EXPAND THE SOUTHERN EXTENT OF THE SNOWFALL TO SHOW A PERIOD OF SNOW MOVING EAST THROUGH THE AREA. THIS SNOW IS ASSOCIATED WITH THE SHORTWAVE SEEN ON WV IMAGERY MOVING ACROSS WESTERN LAKE SUPERIOR AND INTO WESTERN UPPER MICHIGAN AND AN AREA OF MID LEVEL FGEN AND Q-VECTOR CONVERGENCE. OVER THE LAST HOUR OR TWO...THE SNOW HAS INCREASED IN INTENSITY ON RADAR AND WE HAVE SEEN 1.1 INCHES THUS FAR AT THE OFFICE. THUS...TWEAKED UP SNOWFALL AMOUNTS OVER THE NORTH HALF OF THE EASTERN CWA TO AN ADDITIONAL INCH THROUGH THE AFTERNOON. DRY AIR SURGING IN BEHIND THE SHORTWAVE HAS BROUGHT AN END TO THE SYNOPTIC SNOW OUT WEST AND VISIBLE SATELLITE SHOWS THAT LAKE EFFECT SNOW BANDS HAVE DEVELOPED OVER THE WESTERN LAKE. WILL HOLD ONTO SCATTERED SNOW SHOWERS OVER THE WEST THROUGH THE AFTERNOON AND HAVE MADE AN ADJUSTMENT UP TO POPS /TO HIGH END SCATTERED/ OVER THE KEWEENAW THIS EVENING...AS COLDER AIR ROTATES SOUTHEAST BEHIND THE SHORTWAVE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 534 AM EST WED MAR 6 2013 INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH. TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH. FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS AROUND 600MB. STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH. THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING. MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM GUIDANCE. MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI BORDER. OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN. ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA. TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS DROP BELOW ZERO IN A FEW SPOTS WELL INLAND. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 534 AM EST WED MAR 6 2013 HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS. UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH HIGHS GENERALLY IN THE LOWER TO MID 30S. BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST ...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT NIGHT. HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW. MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 648 AM EST WED MAR 6 2013 A WEAK TROUGH MOVING THROUGH THE AREA WILL BRING LIGHT SNOW TO ALL TAF SITES TODAY...AFFECTING IWD AND CMX THIS MORNING...AND SAW THROUGH THE AFTERNOON. VIS SHOULD REMAIN GENERALLY IN THE IFR RANGE...WITH CIGS IN THE MVFR RANGE. UPSLOPE WINDS AT ALL SITES WILL HELP KEEP CIGS LOWER FOR MUCH OF THE DAY. THE TROUGH WILL MOVE EAST DURING THE DAY...BUT EXPECT LAKE ENHANCED SNOW SHOWERS TO CONTINUE INTO THE EVENING NEAR LAKE SUPERIOR. VIS SHOULD IMPROVE AT ALL SITES BY LATE THIS AFTERNOON WHILE CIGS REMAIN IN THE MVFR RANGE. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 534 AM EST WED MAR 6 2013 A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS. EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY AFTERNOON AND EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...SRF SHORT TERM...TK LONG TERM...VOSS AVIATION...TK MARINE...TK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
649 AM EST WED MAR 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 534 AM EST WED MAR 6 2013 INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH. TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH. FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS AROUND 600MB. STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH. THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING. MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM GUIDANCE. MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI BORDER. OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN. ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA. TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS DROP BELOW ZERO IN A FEW SPOTS WELL INLAND. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 534 AM EST WED MAR 6 2013 HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS. UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH HIGHS GENERALLY IN THE LOWER TO MID 30S. BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST ...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT NIGHT. HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW. MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 648 AM EST WED MAR 6 2013 A WEAK TROUGH MOVING THROUGH THE AREA WILL BRING LIGHT SNOW TO ALL TAF SITES TODAY...AFFECTING IWD AND CMX THIS MORNING...AND SAW THROUGH THE AFTERNOON. VIS SHOULD REMAIN GENERALLY IN THE IFR RANGE...WITH CIGS IN THE MVFR RANGE. UPSLOPE WINDS AT ALL SITES WILL HELP KEEP CIGS LOWER FOR MUCH OF THE DAY. THE TROUGH WILL MOVE EAST DURING THE DAY...BUT EXPECT LAKE ENHANCED SNOW SHOWERS TO CONTINUE INTO THE EVENING NEAR LAKE SUPERIOR. VIS SHOULD IMPROVE AT ALL SITES BY LATE THIS AFTERNOON WHILE CIGS REMAIN IN THE MVFR RANGE. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 534 AM EST WED MAR 6 2013 A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS. EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY AFTERNOON AND EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...TK LONG TERM...VOSS AVIATION...TK MARINE...TK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
535 AM EST WED MAR 6 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 534 AM EST WED MAR 6 2013 INITIAL CONCERNS THIS MORNING COME FROM WIDESPREAD -FZDZ ACROSS THE NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION THROUGH THE MORNING COMMUTE. -FZDZ SHOULD TURN OVER TO SNOW BY SUNRISE AS TEMPS ALOFT COOL IN RESPONSE TO THE TROUGH. TODAY...MAIN FOCUS IS ON SNOW POTENTIAL FOR THE NORTHERN HALF THROUGHOUT THE DAY. A VERY WELL DEFINED SHORTWAVE TROUGH OVER FAR WESTERN ONTARIO IS ROTATING AROUND THE BASE OF A LARGE SCALE TROUGH OVER CENTRAL CANADA. WIDESPREAD LIGHT SNOW IS CURRENTLY MOVING ACROSS FAR NE MN AND WESTERN LAKE SUPERIOR AHEAD OF THIS TROUGH. FORCING APPEARS TO BE TIED TO AN ACTIVE REGION OF FRONTOGENESIS AROUND 600MB. STRONGEST FORCING ALONG THE FRONTOGENESIS BAND IS PUSHING NORTHEASTWARD AS THE SHORTWAVE PIVOTS AROUND THE LARGE SCALE TROUGH. THIS TREND IS QUITE EVIDENT ON WV IMAGERY EARLY THIS MORNING. MEANWHILE...A FAIRLY DEFINED SHORTWAVE TROUGH THAT WAS OBSERVED ON WV IMAGERY AND RAP ANALYSIS OVER SOUTHERN MANITOBA EARLY THIS MORNING IS QUICKLY LOSING ITS DEFINITION. THOUGH MODELS ARE SHOWING THAT THIS SMALL SHORTWAVE WILL REINFORCE THE DECAYING WAVE OVER MN...HAVE A FEELING MODELS ARE NOT HANDLING THE SMALL NATURE OF THE WAVE VERY WELL. THE NAM APPEARS TO BE MOST AGGRESSIVE WITH THIS SYSTEM...SO WILL LOOK MORE TOWARD THE GFS/RAP FOR SHORT TERM GUIDANCE. MAIN PRECIP IS FOLLOWING BEHIND A WEAK SFC TROUGH. WINDS WILL BACK MORE OUT OF THE NORTHWEST BEHIND THE TROUGH...SO BEST PRECIP CHANCES WILL FOCUS IN UPSLOPE REGIONS FAVORED BY NW WINDS. OVERALL...HAVE CUT BACK ON POP/QPF/SNOW AMOUNTS...BUT NOT MUCH AS THE LEFT EXIT OF A STRENGTHENING 100KT UPPER JET WILL MOVE TROUGH NORTHERN WI. NOT GREAT ALIGNMENT WITH BEST MID-LEVEL Q-VECTOR CONV OVER AND NORTH OF LAKE SUPERIOR...BUT ENOUGH TO KEEP SLIGHT CHANCE POPS ALONG THE WI BORDER. OVERALL EXPECTATION IS FOR AROUND AN INCH OF SNOW FOR MOST LOCATIONS ALONG LAKE SUPERIOR...WITH UP TO 2 INCHES FOR THE HIGHER TERRAIN. ONLY A DUSTING IS EXPECTED FOR THE SOUTHERN CWA. TONIGHT...MAIN FOCUS TURNS TO LINGERING CLOUD COVER AND HOW IT WILL AFFECT LOW TEMPS. SUBSIDENCE BEHIND THE SHORTWAVE QUICKLY TAKES HOLD LATE THIS AFTERNOON ACROSS THE WEST HALF...LEADING TO A SHALLOW STRATUS DECK. ONLY A COUPLE MODELS ARE MORE AGGRESSIVE WITH KEEPING CLOUDS AROUND. GIVEN THAT THE MARCH SUN SHOULD BE MORE EFFICIENT IN SOMEWHAT MIXING OUT LOW STRATUS LATE THIS AFTERNOON...FEELING IS THAT LOCATIONS AWAY FROM UPSLOPE INFLUENCE IN THE WEST WILL SEE ENOUGH CLEARING TO ALLOW FOR DECENT COOLING OVERNIGHT. LOWERED TEMPS A FEW DEGREES ALONG THE BORDER...AND WOULD NOT BE SURPRISED IF LOWS DROP BELOW ZERO IN A FEW SPOTS WELL INLAND. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 534 AM EST WED MAR 6 2013 HIGH PRESSURE BUILDING OVER THE AREA WILL WEAKEN NRLY WINDS EVENTUALLY CAUSING THEM TO BECOME VARIABLE OVER THE WEST. WITH THE STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL BE IF CLOUDS SCOUR OUT. PER PREV FCST...WILL HOLD ONTO THE CLOUDS THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY SUNNY SKY AS DIURNAL MIXING SHOULD HELP ERODE CLOUDS. UPPER RIDGE OVER THE AREA THURSDAY NIGHT INTO FRIDAY WILL MAINTAIN DRY WEATHER. WITH LIGHT WINDS AND CLEAR SKIES UNDER SFC RIDGE AXIS...DECIDED TO LOWER MIN TEMPS THU NIGHT INTO THE SINGLE DIGITS ABV ZERO OVER CENTRAL AND ERN INTERIOR. INCREASING CLOUDS AND ONSET OF RETURN FLOW SRLY WINDS...WILL KEEP TEMPS MORE IN THE LOW TO MID TEENS WEST. WARM ADVECTION AHEAD OF SHORTWAVE AND ASSOC JET MAX MOVING ACROSS THE NRN PLAINS AND SCNTRL CANADA SHOULD RESULT IN INCREASING MID AND HIGH CLOUDS ON FRIDAY. WITH INCREASING SRLY FLOW...LOOK FOR TEMPS TO REACH WELL INTO THE 30S OVER WEST HALF...PERHAPS EVEN REACHING 40F FOR DOWNSLOPING LOCATIONS ALONG LAKE SUPERIOR. FLOW OFF LAKE MICHIGAN WILL KEEP THE EAST COOLER WITH HIGHS GENERALLY IN THE LOWER TO MID 30S. BY SATURDAY...AN UPPER TROUGH AND ASSOC CLOSED LOW WILL BE PARKED OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE MOVING THROUGH MANITOBA/SASKATCHEWAN. THE 00Z GFS AND GEM-NH SEEM TO INDICATE MORE PHASING OF THESE FEATURES THAN THE 00Z ECMWF BUT EVEN THE ECMWF SHOWS SOME SHORTWAVE ENERGY EJECTING NE FM TROUGH OVER THE SOUTHWEST CONUS AND MERGING WITH VIGOROUS NRN STREAM SHORTWAVE MOVING ACROSS THE UPPER GREAT LAKES. THE NRN STREAM SHORTWAVE WILL HAVE MORE OF AN IMPACT ON OUR WEATHER AND GIVEN THAT THE BEST FORCING STAYS GENERALLY NW OF THE FCST AREA ALONG TRACK OF SHORTWAVE...THE BEST CHC FOR PCPN SHOULD BE OVER THE FAR WRN FCST AREA. DYNAMICS AND MODEL AVG QPF ARGUE FOR LIKELY POPS WEST ON SATURDAY TAPERING TO LOW CHC POPS EAST. COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN AND HAVE DECIDED TO MENTION POSSIBLE ACCUMULATING SNOW IN THE HWO. WITH 850MB TEMPS ABV 0C OVER THE SOUTH CENTRAL HAVE KEPT IN MENTION OF RAIN/SNOW MIX FOR THESE LOCATIONS. AS FRONTAL BOUNDARY MOVES EAST ...LOOK FOR HIGHER CHC TO LIKELY POPS TO TRANSLATE OVER MAINLY EAST HALF SAT NIGHT WHILE STEADY PCPN TAPERS OFF OVER THE WEST LATE SAT NIGHT. HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES FOR SUNDAY INTO SUNDAY NIGHT PROVIDING FOR DRIER CONDITIONS BEHIND THE FRONT EXCEPT FOR THE LINGERING LIGHT LES POSSIBLE ALONG LAKE SUPERIOR. MORE UNCERTAINTY BY MONDAY AS THE GFS SHOWS PHASING OF SRN STREAM SHORTWAVE WITH NRN STREAM AND DEVELOPING WOUND UP SFC LOW TRACKING OVER LOWER MI INTO LAKE HURON. THE GFS SOLN WOULD DRAW IN COLDER AIR IN A STRONGER CYCLONIC NRLY FLOW FOR POSSIBLE LAKE ENHANCED SNOW. MEANWHILE...THE ECMWF KEEPS THE SRN STREAM WAVE TRACKING FARTHER SE THROUGH THE OHIO VALLEY WITH LTL TO NO IMPACT ON OUR WEATHER. THE ECMWF SHOWS HINT OF ANOTHER WEAK CLIPPER SHORTWAVE MOVING OVER AREA FOR TUESDAY. FOR NOW...UNTIL MODELS COME INTO BETTER AGREEMENT WILL CONTINUE GOING SLIGHT CHC POPS IN FCST FOR MONDAY INTO TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1235 AM EST WED MAR 6 2013 DRY AIR CONTINUES TO DELAY THINGS AND PUSHED THE TIMING BACK A BIT. WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS OVERNIGHT WITH -SHSN DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR BY MORNING UNDER FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR OVERNIGHT BEFORE FALLING TO PREVAILING IFR BY MORNING. AT KSAW...MVFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP LATE TONIGHT. FAVORABLE CONVERGENT UPSLOPE FLOW WED MORNING WILL RESULT IN CIGS FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER WED MORNING INTO THE EARLY AFTERNOON WHERE MVFR CONDITIONS WILL THEN PREVAIL. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 534 AM EST WED MAR 6 2013 A WEAK TROUGH WILL PASS ACROSS LAKE SUPERIOR TODAY AND BRING NW WINDS OF 15 TO 25 KNOTS TO THE EASTERN HALF OF LAKE SUPERIOR LATE THIS AFTERNOON THROUGH TONIGHT. A SURFACE RIDGE WILL THEN MOVE ACROSS THE AREA THURSDAY INTO FRIDAY AND BRING WINDS UNDER 15 KNOTS. EXPECT SOUTH WINDS TO INCREASE TO 15 TO 25 KNOTS BY FRIDAY AFTERNOON FOR CENTRAL AND EASTERN LAKE SUPERIOR. LIGHT WINDS WILL PREVAIL AGAIN SATURDAY INTO SUNDAY BEFORE A COLD FRONT CROSSES LAKE SUPERIOR AND USHERS IN NW WINDS OF 15 TO 25 KNOTS OVER THE ENTIRE LAKE SUNDAY AFTERNOON AND EVENING. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...TK LONG TERM...VOSS AVIATION...07 MARINE...TK
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
341 AM EST WED MAR 6 2013 .UPDATE... ISSUED AT 340 AM EST WED MAR 6 2013 QUICK UPDATE THIS MORNING CONCERNING FREEZING DRIZZLE ACROSS THE NORTHERN CWA. PROFILE TEMPS AT OR ABOVE -10C ARE ALLOWING FOR PRECIP TO STAY GENERALLY IN LIQUID FORM. THERE HAVE BEEN REPORTS OF ROADS BECOMING SLIPPERY...AND A DECENT GLAZE HAS BEEN OBSERVED AT OUR OFFICE. HAVE INCREASED POPS TO WIDESPREAD -FZDZ EARLY THIS MORNING...AND ISSUED A SPECIAL WX STATEMENT TO ADVISE CAUTION THROUGH THE MORNING COMMUTE. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 407 PM EST TUE MAR 5 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS SHORTWAVE DROPPING SE INTO THE MID MISSISSIPPI VALLEY. WAVE IS BEING FORCED SE BY MID LEVEL HIGH OVER QUEBEC. AS A RESULT...SYSTEM SNOW HAS PAST BY TO THE W AND S OF UPPER MI TODAY. SOME VERY LIGHT LES IS OCCURRING IN E TO NE FLOW ACROSS LAKE SUPERIOR INTO THE KEWEENAW AND NCNTRL UPPER MI AS TEMPS AT THE BASE OF A LOW 3KFT INVERSION ARE JUST SUFFICIENT FOR LES AT -11C. UNDER DOWNSLOPING E TO NE LOW-LEVEL WINDS...THE ERN FCST AREA HAS ENJOYED A SUNNY DAY TODAY. VIGOROUS SHORTWAVE/MID LEVEL LOW OVER THE MID MISSISSIPPI VALLEY WILL MOVE TO VCNTY OF NC BY WED MORNING AND WILL HAVE LITTLE IMPACT ON WEATHER HERE. WHAT WILL BE A FACTOR IS A NRN STREAM SHORTWAVE THAT WILL BE DRIFTING INTO THE UPPER LAKES LATE TONIGHT/WED... BRINGING A DECENT AREA OF DEEP LAYER FORCING PER QVECTORS. THE APPROACHING SHORTWAVE WILL HELP SHARPEN LOW-LEVEL CYCLONIC N TO NE FLOW ACROSS LAKE SUPERIOR TONIGHT/WED MORNING BEFORE WINDS SHIFT NW WED AS THE WAVE REACHES THE AREA. WHILE LOW-LEVEL THERMAL PROFILE CHANGES VERY LITTLE...OVERWATER INSTABILITY IS MORE THAN SUFFICIENT FOR LAKE ENHANCEMENT...AND THE FACT THAT SOME VERY LIGHT LES IS ALREADY OCCURRING SUGGESTS THERE SHOULD BE A DECENT UPTICK IN LES TONIGHT/WED MORNING. WITH ALL MODEL GUIDANCE SHOWING A SSE TO NNW ORIENTED SFC TROF DEVELOPING ACROSS ROUGHLY CNTRL LAKE SUPERIOR...IT WOULD APPEAR THAT NW AND NCNTRL UPPER MI SHOULD BE FAVORED FOR MORE PERSISTENT SNOW. SNOW TO WATER RATIOS SHOULD BE ON THE LOW SIDE 10-15 TO 1...EXCEPT IN THE VCNTY/ALONG THE AFORENTIONED SFC TROF WHERE DEEPER VERTICAL MOTION...THOUGH NOT STRONG...SHOULD INTERSECT THE DGZ AND POSSIBLY BOOST RATIOS TOWARD 20 TO 1. AT THIS POINT...IT APPEARS ACCUMULATIONS UPWARDS OF AROUND 3 INCHES ARE POSSIBLE OVER NW/NCNTRL HIGHER TERRAIN TONIGHT/WED MORNING. ACCUMULATIONS SHOULD BE A LITTLE LESS FARTHER W TOWARD KIWD. IT REALLY WON`T BE UNTIL LATER WED MORNING/AFTN WHEN SFC TROF PASSES THAT SNOW REACHES THE NE FCST AREA. AWAY FROM LAKE ENHANCEMENT...EXPECT SOME -SN/-SHSN TIED TO SHORT PERIOD OF STRONGER FORCING ASSOCIATED WITH SHORTWAVE. -SHSN WILL DIMINISH W TO E WED AFTN AND MAY END OVER THE W. TEMPS TONIGHT ARE FAIRLY STRAIGHTFORWARD WITH CLOUD COVER LIMITING TEMP FALL. ONE EXCEPTION IS THE ERN FCST AREA AS IT`S UNCERTAIN WHEN CLOUDS WILL INCREASE SUFFICIENTLY TO SLOW/STOP TEMP FALL THERE TONIGHT. GIVEN THAT IT`S SUNNY IN THAT AREA NOW...AND SATELLITE IMAGERY SHOWS NO TREND TO CLOUD UP SOON...TEMPS COULD PLUMMET QUICKLY THIS EVENING. FCST WILL SHOW MINS IN THE MID TEENS...BUT IT`S QUITE POSSIBLE TEMPS COULD FALL WELL DOWN INTO THE SINGLE DIGITS DURING THE EVENING IF IT REMAINS MOSTLY CLEAR. MID 20S TO LWR 30S SHOULD BE THE RULE WED. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 407 PM EST TUE MAR 5 2013 LINGERING SURFACE TROUGH AND NORTHERN STREAM SHORTWAVE WILL BE SLIDING EAST ACROSS EASTERN LAKE SUPERIOR ON WEDNESDAY EVENING WHILE AN AREA OF HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES. WITH 900MB TEMPS STILL AROUND -12C AND ENOUGH LOW LEVEL MOISTURE BELOW THE 3-4KFT INVERSION...SHOULD STILL SEE LOW CLOUDS ACROSS THE AREA DURING THE EVENING IN THE NORTH-NORTHWEST WIND LOCATIONS. DURING THE EVENING...WOULD EXPECT ISOLATED/SCATTERED SNOW SHOWERS IN THOSE SAME WIND FAVORED LOCATIONS. WITH A LITTLE DEEPER MOISTURE OVER THE EASTERN LOCATIONS...MAINLY FROM MUNISING EASTWARD...WOULD EXPECT ISOLATED LIGHT SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT. OVER THE WEST...THE INFLUENCE OF THE HIGH WILL ALLOW THE FLOW TO BECOME ANTI-CYCLONIC THROUGH THE NIGHT AND INCREASE THE DRY AIR OVER THE WESTERN LAKE...SLOWLY DECREASING THE CLOUDS IN THAT AREA. THIS DECREASE IN CLOUDS LEADS TO UNCERTAINTY IN THE LOWS OVER THE WESTERN CWA. WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF NORMAL...LOCATIONS THAT DO CLEAR OUT WILL LIKELY FALL INTO THE SINGLE DIGITS AND WOULDN/T BE SURPRISED TO SEE A FEW BELOW ZERO READINGS IN THE COLD SPOTS OF EASTERN GOGEBIC AND IRON COUNTY. THE HIGH WILL CONTINUE TO MOVE OVER THE AREA ON THURSDAY...CAUSING WINDS TO BECOME MORE VARIABLE. WITH THE STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL BE WHERE THE CLOUDS WILL BE LOCATED AND IF/WHEN THEY WILL MIX OUT. WILL HOLD ONTO THE CLOUDS THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY SUNNY SKY AS DIURNAL MIXING WILL LIKELY EAT AWAY AT THE CLOUDS. UPPER RIDGE BUILDS OVER THE AREA ON THURSDAY NIGHT INTO FRIDAY...WHICH WILL KEEP THE AREA DRY AND ONLY PRODUCE SOME MID-HIGH CLOUDS STREAMING ACROSS THE AREA. BY FRIDAY NIGHT...AN UPPER TROUGH WILL BE SITTING OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE MOVING THROUGH MANITOBA/SASKATCHEWAN. THE QUESTION BECOMES WHETHER THESE TWO TROUGHS WILL SEPARATE OR STAY TOGETHER...WHICH THEN INFLUENCES THE FORECAST INTO THE FIRST PART OF NEXT WEEK. THE LATEST TRENDS IN THE 12Z MODEL RUNS IS TO KEEP THE WAVES PHASED ENOUGH THROUGH THE WEEKEND DUE TO A STRONGER NORTHERN STREAM WAVE. THIS IN TURN LEADS TO STRONGER FORCING WITH THE SURFACE TROUGH MOVING THROUGH SATURDAY INTO SATURDAY EVENING. WITH THIS STRONGER WAVE AND INCREASED SOUTHERLY FLOW AHEAD OF THE SYSTEM...MODELS HAVE TRENDED UP WITH THE QPF...ESPECIALLY OVER THE WESTERN HALF OF THE CWA. HAVE TRENDED POPS UP FOR THIS PERIOD AND WITH SOME OF THE QPF AMOUNTS SHOWN ON THE 12Z RUNS...COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN. WON/T MENTION THIS IN THE HWO AT THIS POINT WITH THE WAY THE MODELS HAVE BEEN VARYING...BUT WILL BE SOMETHING TO WATCH. FINALLY...LOOKING AT MODEL SOUNDINGS...THEY TRY TO NOSE TEMPS ABOVE 0C AROUND 850MB OVER THE SOUTH CENTRAL WHICH COULD LEAD TO SOME MELTING ALONG THE ISOTHERMAL LAYER TO THE SURFACE. THUS...ADDED A MIX OF RAIN/SNOW TO THAT AREA. HIGH PRESSURE WILL LIKELY BUILD INTO THE UPPER GREAT LAKES FOR SUNDAY AND THE FIRST PART OF MONDAY...BEFORE THE NEARLY CLOSED SOUTHERN STREAM TROUGH DRIFTS OUT OF THE SOUTHWEST CONUS. WHILE THIS SYSTEM WAS LOOKING LIKE IT WAS GOING TO MOVE TOWARDS THE UPPER GREAT LAKES ON THE 12Z RUNS YESTERDAY...THE LATEST TRENDS HAVE IT MOVING MORE THROUGH THE OHIO RIVER VALLEY. THEREFORE...HAVE TRENDED POPS DOWN FOR THE MONDAY PERIOD AND IF THE TREND CONTINUES THEY MAY NEED TO BE REMOVED COMPLETELY. AS FOR TEMPERATURES DURING THE LONG TERM PERIOD...IT LOOKS TO BE FAIRLY NORMAL WITH A FEW DAYS OF SLIGHTLY ABOVE NORMAL HIGHS THROUGH THE WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1235 AM EST WED MAR 6 2013 DRY AIR CONTINUES TO DELAY THINGS AND PUSHED THE TIMING BACK A BIT. WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS OVERNIGHT WITH -SHSN DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR BY MORNING UNDER FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR OVERNIGHT BEFORE FALLING TO PREVAILING IFR BY MORNING. AT KSAW...MVFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP LATE TONIGHT. FAVORABLE CONVERGENT UPSLOPE FLOW WED MORNING WILL RESULT IN CIGS FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER WED MORNING INTO THE EARLY AFTERNOON WHERE MVFR CONDITIONS WILL THEN PREVAIL. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 407 PM EST TUE MAR 5 2013 NE TO N WINDS OF 15-25KT WILL BE THE RULE ACROSS LAKE SUPERIOR TONIGHT...THOUGH 20-30KT WINDS WILL LINGER OVER THE WRN PORTION OF THE LAKE INTO THE EVENING HRS BEFORE PRES GRADIENT BEGINS TO RELAX. WINDS WILL FALL OFF TO UNDER 20KT OVER WRN LAKE SUPERIOR WED. OVER ERN LAKE SUPERIOR...TIGHTER PRES GRADIENT WILL ALLOW 15-25KT WINDS TO PERSIST INTO EARLY THU MORNING. HIGH PRES RIDGE PASSING OVER THE AREA WILL THEN LEAD TO WINDS UNDER 20KT ACROSS THE LAKE THU/FRI. ALTHOUGH A LOW PRES TROF WILL PASS ACROSS LAKE SUPERIOR LATER SAT/EARLY SUN...PRES GRADIENT REMAINS WEAK...KEEPING WINDS MOSTLY UNDER 20KT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...TK SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...07 MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1236 AM EST WED MAR 6 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 407 PM EST TUE MAR 5 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW A VIGOROUS SHORTWAVE DROPPING SE INTO THE MID MISSISSIPPI VALLEY. WAVE IS BEING FORCED SE BY MID LEVEL HIGH OVER QUEBEC. AS A RESULT...SYSTEM SNOW HAS PAST BY TO THE W AND S OF UPPER MI TODAY. SOME VERY LIGHT LES IS OCCURRING IN E TO NE FLOW ACROSS LAKE SUPERIOR INTO THE KEWEENAW AND NCNTRL UPPER MI AS TEMPS AT THE BASE OF A LOW 3KFT INVERSION ARE JUST SUFFICIENT FOR LES AT -11C. UNDER DOWNSLOPING E TO NE LOW-LEVEL WINDS...THE ERN FCST AREA HAS ENJOYED A SUNNY DAY TODAY. VIGOROUS SHORTWAVE/MID LEVEL LOW OVER THE MID MISSISSIPPI VALLEY WILL MOVE TO VCNTY OF NC BY WED MORNING AND WILL HAVE LITTLE IMPACT ON WEATHER HERE. WHAT WILL BE A FACTOR IS A NRN STREAM SHORTWAVE THAT WILL BE DRIFTING INTO THE UPPER LAKES LATE TONIGHT/WED... BRINGING A DECENT AREA OF DEEP LAYER FORCING PER QVECTORS. THE APPROACHING SHORTWAVE WILL HELP SHARPEN LOW-LEVEL CYCLONIC N TO NE FLOW ACROSS LAKE SUPERIOR TONIGHT/WED MORNING BEFORE WINDS SHIFT NW WED AS THE WAVE REACHES THE AREA. WHILE LOW-LEVEL THERMAL PROFILE CHANGES VERY LITTLE...OVERWATER INSTABILITY IS MORE THAN SUFFICIENT FOR LAKE ENHANCEMENT...AND THE FACT THAT SOME VERY LIGHT LES IS ALREADY OCCURRING SUGGESTS THERE SHOULD BE A DECENT UPTICK IN LES TONIGHT/WED MORNING. WITH ALL MODEL GUIDANCE SHOWING A SSE TO NNW ORIENTED SFC TROF DEVELOPING ACROSS ROUGHLY CNTRL LAKE SUPERIOR...IT WOULD APPEAR THAT NW AND NCNTRL UPPER MI SHOULD BE FAVORED FOR MORE PERSISTENT SNOW. SNOW TO WATER RATIOS SHOULD BE ON THE LOW SIDE 10-15 TO 1...EXCEPT IN THE VCNTY/ALONG THE AFORENTIONED SFC TROF WHERE DEEPER VERTICAL MOTION...THOUGH NOT STRONG...SHOULD INTERSECT THE DGZ AND POSSIBLY BOOST RATIOS TOWARD 20 TO 1. AT THIS POINT...IT APPEARS ACCUMULATIONS UPWARDS OF AROUND 3 INCHES ARE POSSIBLE OVER NW/NCNTRL HIGHER TERRAIN TONIGHT/WED MORNING. ACCUMULATIONS SHOULD BE A LITTLE LESS FARTHER W TOWARD KIWD. IT REALLY WON`T BE UNTIL LATER WED MORNING/AFTN WHEN SFC TROF PASSES THAT SNOW REACHES THE NE FCST AREA. AWAY FROM LAKE ENHANCEMENT...EXPECT SOME -SN/-SHSN TIED TO SHORT PERIOD OF STRONGER FORCING ASSOCIATED WITH SHORTWAVE. -SHSN WILL DIMINISH W TO E WED AFTN AND MAY END OVER THE W. TEMPS TONIGHT ARE FAIRLY STRAIGHTFORWARD WITH CLOUD COVER LIMITING TEMP FALL. ONE EXCEPTION IS THE ERN FCST AREA AS IT`S UNCERTAIN WHEN CLOUDS WILL INCREASE SUFFICIENTLY TO SLOW/STOP TEMP FALL THERE TONIGHT. GIVEN THAT IT`S SUNNY IN THAT AREA NOW...AND SATELLITE IMAGERY SHOWS NO TREND TO CLOUD UP SOON...TEMPS COULD PLUMMET QUICKLY THIS EVENING. FCST WILL SHOW MINS IN THE MID TEENS...BUT IT`S QUITE POSSIBLE TEMPS COULD FALL WELL DOWN INTO THE SINGLE DIGITS DURING THE EVENING IF IT REMAINS MOSTLY CLEAR. MID 20S TO LWR 30S SHOULD BE THE RULE WED. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 407 PM EST TUE MAR 5 2013 LINGERING SURFACE TROUGH AND NORTHERN STREAM SHORTWAVE WILL BE SLIDING EAST ACROSS EASTERN LAKE SUPERIOR ON WEDNESDAY EVENING WHILE AN AREA OF HIGH PRESSURE BUILDS INTO THE UPPER GREAT LAKES. WITH 900MB TEMPS STILL AROUND -12C AND ENOUGH LOW LEVEL MOISTURE BELOW THE 3-4KFT INVERSION...SHOULD STILL SEE LOW CLOUDS ACROSS THE AREA DURING THE EVENING IN THE NORTH-NORTHWEST WIND LOCATIONS. DURING THE EVENING...WOULD EXPECT ISOLATED/SCATTERED SNOW SHOWERS IN THOSE SAME WIND FAVORED LOCATIONS. WITH A LITTLE DEEPER MOISTURE OVER THE EASTERN LOCATIONS...MAINLY FROM MUNISING EASTWARD...WOULD EXPECT ISOLATED LIGHT SNOW SHOWERS TO CONTINUE THROUGH THE NIGHT. OVER THE WEST...THE INFLUENCE OF THE HIGH WILL ALLOW THE FLOW TO BECOME ANTI-CYCLONIC THROUGH THE NIGHT AND INCREASE THE DRY AIR OVER THE WESTERN LAKE...SLOWLY DECREASING THE CLOUDS IN THAT AREA. THIS DECREASE IN CLOUDS LEADS TO UNCERTAINTY IN THE LOWS OVER THE WESTERN CWA. WITH LIGHT WINDS AND PWATS AROUND 50 PERCENT OF NORMAL...LOCATIONS THAT DO CLEAR OUT WILL LIKELY FALL INTO THE SINGLE DIGITS AND WOULDN/T BE SURPRISED TO SEE A FEW BELOW ZERO READINGS IN THE COLD SPOTS OF EASTERN GOGEBIC AND IRON COUNTY. THE HIGH WILL CONTINUE TO MOVE OVER THE AREA ON THURSDAY...CAUSING WINDS TO BECOME MORE VARIABLE. WITH THE STRENGTHENING SUBSIDENCE INVERSION...THE QUESTION FOR THURSDAY WILL BE WHERE THE CLOUDS WILL BE LOCATED AND IF/WHEN THEY WILL MIX OUT. WILL HOLD ONTO THE CLOUDS THE LONGEST OVER THE EAST WHERE THE NORTHWEST WINDS WILL BE MOST PERSISTENT. ELSEWHERE...WENT WITH MORE OF A PARTLY CLOUDY TO MOSTLY SUNNY SKY AS DIURNAL MIXING WILL LIKELY EAT AWAY AT THE CLOUDS. UPPER RIDGE BUILDS OVER THE AREA ON THURSDAY NIGHT INTO FRIDAY...WHICH WILL KEEP THE AREA DRY AND ONLY PRODUCE SOME MID-HIGH CLOUDS STREAMING ACROSS THE AREA. BY FRIDAY NIGHT...AN UPPER TROUGH WILL BE SITTING OVER THE SOUTHWEST CONUS AND A NORTHERN STREAM TROUGH WILL BE MOVING THROUGH MANITOBA/SASKATCHEWAN. THE QUESTION BECOMES WHETHER THESE TWO TROUGHS WILL SEPARATE OR STAY TOGETHER...WHICH THEN INFLUENCES THE FORECAST INTO THE FIRST PART OF NEXT WEEK. THE LATEST TRENDS IN THE 12Z MODEL RUNS IS TO KEEP THE WAVES PHASED ENOUGH THROUGH THE WEEKEND DUE TO A STRONGER NORTHERN STREAM WAVE. THIS IN TURN LEADS TO STRONGER FORCING WITH THE SURFACE TROUGH MOVING THROUGH SATURDAY INTO SATURDAY EVENING. WITH THIS STRONGER WAVE AND INCREASED SOUTHERLY FLOW AHEAD OF THE SYSTEM...MODELS HAVE TRENDED UP WITH THE QPF...ESPECIALLY OVER THE WESTERN HALF OF THE CWA. HAVE TRENDED POPS UP FOR THIS PERIOD AND WITH SOME OF THE QPF AMOUNTS SHOWN ON THE 12Z RUNS...COULD SEE NEAR ADVISORY SNOWFALL FOR SOME LOCATIONS OVER WESTERN UPPER MICHIGAN. WON/T MENTION THIS IN THE HWO AT THIS POINT WITH THE WAY THE MODELS HAVE BEEN VARYING...BUT WILL BE SOMETHING TO WATCH. FINALLY...LOOKING AT MODEL SOUNDINGS...THEY TRY TO NOSE TEMPS ABOVE 0C AROUND 850MB OVER THE SOUTH CENTRAL WHICH COULD LEAD TO SOME MELTING ALONG THE ISOTHERMAL LAYER TO THE SURFACE. THUS...ADDED A MIX OF RAIN/SNOW TO THAT AREA. HIGH PRESSURE WILL LIKELY BUILD INTO THE UPPER GREAT LAKES FOR SUNDAY AND THE FIRST PART OF MONDAY...BEFORE THE NEARLY CLOSED SOUTHERN STREAM TROUGH DRIFTS OUT OF THE SOUTHWEST CONUS. WHILE THIS SYSTEM WAS LOOKING LIKE IT WAS GOING TO MOVE TOWARDS THE UPPER GREAT LAKES ON THE 12Z RUNS YESTERDAY...THE LATEST TRENDS HAVE IT MOVING MORE THROUGH THE OHIO RIVER VALLEY. THEREFORE...HAVE TRENDED POPS DOWN FOR THE MONDAY PERIOD AND IF THE TREND CONTINUES THEY MAY NEED TO BE REMOVED COMPLETELY. AS FOR TEMPERATURES DURING THE LONG TERM PERIOD...IT LOOKS TO BE FAIRLY NORMAL WITH A FEW DAYS OF SLIGHTLY ABOVE NORMAL HIGHS THROUGH THE WEEKEND. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1235 AM EST WED MAR 6 2013 DRY AIR CONTINUES TO DELAY THINGS AND PUSHED THE TIMING BACK A BIT. WITH A DISTURBANCE ARRIVING OVER THE UPPER LAKES LATE TONIGHT/WED MORNING...-SHSN WILL INCREASE IN COVERAGE AND INTENSITY DURING THIS FCST PERIOD. AT KIWD...EXPECT MVFR CONDITIONS OVERNIGHT WITH -SHSN DEVELOPING. CONDITIONS SHOULD SETTLE TO IFR BY MORNING UNDER FAVORABLE UPSLOPE FLOW. AT KCMX...CONDITIONS SHOULD STAY MVFR OVERNIGHT BEFORE FALLING TO PREVAILING IFR BY MORNING. AT KSAW...MVFR CONDITIONS WILL CONTINUE AS -SHSN DEVELOP LATE TONIGHT. FAVORABLE CONVERGENT UPSLOPE FLOW WED MORNING WILL RESULT IN CIGS FALLING TO LIFR. IMPROVEMENT SHOULD OCCUR AT ALL SITES LATER WED MORNING INTO THE EARLY AFTERNOON WHERE MVFR CONDITIONS WILL THEN PREVAIL. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 407 PM EST TUE MAR 5 2013 NE TO N WINDS OF 15-25KT WILL BE THE RULE ACROSS LAKE SUPERIOR TONIGHT...THOUGH 20-30KT WINDS WILL LINGER OVER THE WRN PORTION OF THE LAKE INTO THE EVENING HRS BEFORE PRES GRADIENT BEGINS TO RELAX. WINDS WILL FALL OFF TO UNDER 20KT OVER WRN LAKE SUPERIOR WED. OVER ERN LAKE SUPERIOR...TIGHTER PRES GRADIENT WILL ALLOW 15-25KT WINDS TO PERSIST INTO EARLY THU MORNING. HIGH PRES RIDGE PASSING OVER THE AREA WILL THEN LEAD TO WINDS UNDER 20KT ACROSS THE LAKE THU/FRI. ALTHOUGH A LOW PRES TROF WILL PASS ACROSS LAKE SUPERIOR LATER SAT/EARLY SUN...PRES GRADIENT REMAINS WEAK...KEEPING WINDS MOSTLY UNDER 20KT. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...SRF AVIATION...07 MARINE...ROLFSON
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
406 PM CST WED MAR 6 2013 .DISCUSSION... TONIGHT...CLOUDS HAVE BEEN THINNING OUT ALL AFTERNOON...AND ITS CURRENTLY PRETTY CLEAR OVER WRN WI. THE STRATUS DECK IS MORE EXTENSIVE FURTHER WEST...AND WITH HIGH PRESSURE MOVING OVERHEAD TONIGHT...THE CLOUDS MAY BECOME TRAPPED UNDER THE INVERSION. THE FCST HAS TRENDED WARMER FOR OVERNIGHT LOWS /ESPECIALLY ACROSS WC MN/ WHERE CLOUDS ARE ANTICIPATED TO HANG ON THE LONGEST. TEMPS ARE EXPECTED TO RANGE FROM THE LOWER TEENS ALONG AND WEST OF THE MN RIVER...TO NEAR ZERO IN W WI. WHERE CLEARING DOES OCCUR...RADIATIONAL FOG MAY BECOME AN ISSUE. E CENTRAL MN AND W WI HAVE THE BEST SHOT OF SEEING PATCHY FOG WHERE SKIES SHOULD BE CLEAR THE LONGEST. NOT EXPECTING EXTENSIVE DENSE FOG...BUT WOULD NOT BE SURPRISED IF A FEW SITES DIP AS LOW AS 1/2SM FOR A TIME EARLY THU AM. THURSDAY AND FRIDAY...SURFACE HIGH PRES WILL SLIDE E ACRS THE AREA...RESIDING E OF THE AREA BY THU MRNG. IN CONJUNCTION WILL BE A LONGWAVE UPPER LEVEL RIDGE THAT WILL GLIDE ACRS THE REGION. WHILE THE SFC HIGH E OF THE REGION WILL ALLOW FOR A SOUTHERLY WARMER RETURN SFC FLOW...THE UPPER RIDGING WILL BRING HIGHER H7 AND H5 HEIGHTS THAT WILL ALSO PROMOTE WAA FOR THE REGION FOR BOTH THU-FRI. THIS COMBINATION WILL ALSO KEEP ANY SIGNIFICANT WX SYSTEMS FROM IMPACTING THE REGION SO TEMPERATURES WILL RISE TO NEAR NORMAL LEVELS...WHICH WILL ACTUALLY SEEM LIKE A SIGNIFICANT WARMUP FOR THE REGION. HIGHS WILL REACH THE FREEZING MARK ON THU THEN JUMP TO THE MID AND EVEN UPPER 30S ON FRI. THIS WILL ALLOW FOR DECENT MELTING OF THE SNOWPACK AND SHOULD CAUSE AN APPRECIABLE DECREASE IN SNOW DEPTH. CLOUDS WILL BE ON THE INCREASE FRI WHICH MAY HINDER SOME EVAPORATION BUT THE MELTING SHOULD NOT BE IMPACTED AS MUCH SIMPLY WITH TEMPERATURES WELL ABOVE THE FREEZING MARK. OF COURSE...THE MELTING FOLLOWED BY REFREEZING AT NIGHT MAY CAUSE SOME SLIPPERY ROADS BUT IT IS A LITTLE EARLY TO DETERMINE THE EXTENT OF SUCH CONCERNS. FRIDAY NIGHT THROUGH TUESDAY...SEVERAL LOW PRESSURE SYSTEMS LOOK TO IMPACT THE AREA LATE THIS WEEK INTO EARLY NEXT WEEK WITHIN A PROGRESSIVE SW FLOW ON THE BACKSIDE OF THE DEPARTING UPPER LEVEL RIDGE. A LARGE LONGWAVE TROUGH DIGGING INTO THE 4-CORNERS REGION WILL EJECT A LOW PRESSURE SYSTEM FROM THE COLORADO REGION EWD INTO THE MID-MISSISSIPPI RIVER VALLEY. HIGH PRES NUDGING DOWN FROM CENTRAL CANADA WILL KEEP THE BULK OF THIS SYSTEM FROM SHIFTING N...BUT ENOUGH UPPER LEVEL TROFFING COMBINED WITH AN ATTENDANT SFC TROUGH WILL ALLOW PRECIPITATION TO DEVELOP FROM S TO N STARTING FRI NIGHT AND CONTINUING THRU MOST OF THE WEEKEND. THE CONCERN IS THAT THERE IS LITTLE TO NO COLD AIR ADVECTION ACCOMPANYING THIS SYSTEM SO TEMPERATURES WILL STILL RANGE THROUGH THE 30S DURING THE DAYTIME HOURS FRI-SUN AND IN THE 20S TO NEAR 30 FRI NIGHT AND SAT NIGHT. IN ADDITION...MODEL SOUNDINGS CONTINUE TO ADVERTISE VARYING AREAS THAT WILL DEAL WITH A SHALLOW WARM AIR LAYER OF VARYING DEPTHS...MAKING P-TYPE ISSUES HIGHLY COMPLEX. HAVE CONTINUED TO ADVERTISE A VARIETY OF WINTRY PRECIPITATION FOR THE WEEKEND AND LATER FORECASTS WILL NEED TO BE ADVERTISED. IN ADDITION...QPF LOOKS TO BE HIGHLY ELEVATED WITH SOME MODELS SHOWING AT LEAST AN INCH THROUGH THE WEEKEND...WHICH MAY MAKE FOR HYDROLOGIC CONCERNS...ESPECIALLY ANY SIGNIFICANT RAINFALL ON TOP OF A DECENT SNOWPACK. ONCE THIS COMPLEX SYSTEM SHIFTS OFF TO THE SE SUN NIGHT INTO MON...COLDER HIGH PRES WILL DROP DOWN FROM CANADA MAKING FOR A DRYING OUT PERIOD MON-TUE ALONG WITH TEMPERATURES BACK DOWN BELOW NORMAL. && .AVIATION.../18Z TAF ISSUANCE/ MAIN ISSUE THIS TAF PERIOD IS WHAT WILL HAPPEN WITH EXPANSIVE STRATUS DECK IN PLACE. SFC RIDGE AXIS IS CURRENTLY FROM NEAR SIOUX FALLS TO BISMARK...WITH CONDS MAINLY VFR WEST OF THIS AXIS. THE RIDGE WILL SLIDE ACROSS THE MPX AREA TONIGHT...WHICH WOULD IMPLY SKIES SHOULD CLEAR OUT FROM WEST TO EAST...BUT THIS IS LOOKING LIKE A SCENARIO WHERE LOW LEVEL MOISTURE GETS TRAPPED BENEATH THE INVERSION AND IT TAKES A NEW ROUND OF SOLAR MIXING THURSDAY MORNING TO FINALLY BLAST THE LOW CLOUDS OUT. THIS IS THE SCENARIO THE HRRR PLAYS OUT AND IN GENERAL WHAT WAS FOLLOWED FOR THESE TAFS. ONE THING TO WATCH CLOSELY THOUGH THIS AFTERNOON IS WHAT HAPPENS TO THE HOLE IN STRATUS OVER WRN WI...IF THIS CAN EXPAND SOME THIS AFTERNOON...THEN THERE IS A GOOD CHANCE THAT SKIES WILL STAY CLEAR ACROSS ERN TERMINALS. IF THIS HAPPENS...THEN RNH/EAU WILL LIKELY HAVE TO WORRY ABOUT FOG IN THE MORNING. KMSP...CONFIDENCE IN OPTIMISTIC SKY FORECAST THIS EVENING IS LOW. GOING VFR AT 4Z WILL WORK OUT...SO LONG AS THE CLEARING TO THE EAST CAN EXPAND AND SUSTAIN ITSELF. HOWEVER...COULD VERY WELL SEE THIS NOT HAPPENING...WITH CIGS REMAINING BETWEEN 020 AND 025 UNTIL AFTER 12Z THU...WITH THE POTENTIAL FOR GOING BELOW 017 LATE TONIGHT. FOR WIND DIRECTION...THE SWITCH TOWARD THE SE WILL HAPPEN OVERNIGHT. WITH SPEEDS UNDER 7 KTS...SHOULD GIVE SOME LEE WAY IN RUNWAY CONFIG. BY THU MORNING THOUGH...BOTH NAM/GFS SHOW SE WINDS INCREASING IN INTENSITY...SO WILL MOST LIKELY HAVE TO START TOMORROW ON THE 12S. /OUTLOOK FOR KMSP/ FRI...VFR. MVFR CIGS WITH CHANCE OF FZRA/RA LATE FRI NIGHT. SE WIND 5-10 KTS. SAT...IFR OR LOWER WITH CHANCE OF FZRA/RA. WINDS E 5 KTS. SUN...MVFR WITH CHANCE OF -SN EARLY. WINDS N 10-15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JPC/JCA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1235 PM CST WED MAR 6 2013 .UPDATE... 18Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION... /ISSUED 515 AM CST WED MAR 6 2013/ MAIN FORECAST CONCERN IS THE PRECIPITATION TYPE FOR THE UPCOMING WEEKEND...AND WHETHER THERE WILL BE ICE PROBLEMS. THE STORM SYSTEM THAT HAS PLAGUED THE UPPER MIDWEST FOR THE PAST TWO DAYS HAS MOVED SOUTHEAST AND AFFECTING THE MID-ATLANTIC REGION. RESIDUAL CLOUD COVER AND COOL NORTHERLY FLOW WILL KEEP TEMPS FROM RISING ABV FREEZING FOR THE MOST PART TODAY. HOWEVER...THE MARCH SUN ANGLE IS HIGH ENOUGH TO START THE MELTING PROCESS ACROSS THE REGION...BUT IT SHOULD BE LIMITED WITH THE AMT OF CLOUD COVER EXPECTED. AS THE SFC RIDGE MOVES OVERHEAD TONIGHT...SOME FOG WILL DEVELOP...ESPECIALLY ACROSS EASTERN MN...AND WESTERN WI WHERE WINDS WILL BE LIGHTEST. AFTER WEDNESDAY...A LARGE RIDGE WILL DEVELOP ACROSS THE UPPER MIDWEST IN RESPONSE TO A SHARP TROUGH DIGGING INTO THE SW U.S. THIS WILL ALLOW FOR MUCH WARMER AIR TO SURGE NORTHWARD ACROSS THE PLAINS...AND THE UPPER MIDWEST BY THE END OF THE WEEK. BASED ON THE AMT OF MOISTURE EXPECTED AHEAD OF THIS SYSTEM...WHICH TRANSLATES TO PRECIPITABLE WATER VALUES NEAR 0.80 INCHES /THIS IS ALMOST TWO STANDARD DEVIATIONS ABV NORMAL FOR MSP/ PRECIPITATION IS ALMOST CERTAIN BY LATE FRIDAY/SATURDAY. DEPENDING UPON SFC TEMPS INITIALLY...FREEZING RAIN/SLEET/SNOW WILL OCCUR AT THE BEGINNING LATE FRIDAY NIGHT/EARLY SATURDAY...BEFORE CHANGING OVER TO A MIXTURE OF SNOW/RAIN...OR JUST RAIN. DUE TO THE AMT OF WARM AIR ADVECTING NORTHWARD AND HOW 85H DEW PTS RISE ABV 0C...AM THINKING THAT MOST OF THE PRECIPITATION WILL BE IN THE FORM OF LIQUID. ONLY THE FAR NORTH/NW FA MAY SEE A MIXTURE BASED ON THE MAX WET BULB TEMPS IN THE MIX LAYER UP TO 1KM. THERE REMAINS A LOT OF CONCERN WITH THE DEEP SNOW PACK ACROSS OUR REGION...WHICH MAY HOLD DOWN TEMPS INITIALLY...SO A PERIOD OF SLEET/FREEZING RAIN IS BECOMING LIKELY. WILL UPDATE THE MORNING HWO BASED ON THIS SCENARIO. QPF AMTS ARE ALSO VERY HIGH...AND MAY CAUSE SOME FLOODING IF WE GET SOME TYPE OF CONVECTIVE ELEMENT SATURDAY AFTN. THIS IS MAINLY DUE TO THE FROZEN GROUND AND ABUNDANT SNOW COVER. AS DEW PTS ARE EXPECTED TO RISE ABV FREEZING AND THE COMBINATION OF RAIN ON SNOW FALLING...AND POSSIBLY HIGHER PRECIPITATION RATES...SOME MINOR FLOODING IS POSSIBLE. A COLD FRONT IS EXPECTED TO MOVE ACROSS THE REGION LATE SATURDAY AFTN/EVENING...CAUSING THE PRECIPITATION TO SWITCH OVER TO SNOW. HOWEVER...BUT THAT TIME...MOST OF THE DEEP MOISTURE WOULD BE GONE...LEAVING ONLY LIGHT SNOW AT BEST. ALTHOUGH LONG RANGE CLIMATE MODELS ARE HINTING ON A COOLER PATTERN THE MIDDLE OF MARCH...THE LATEST EC/GFS IS CONSIDERING A MORE ZONAL FLOW BY LATE NEXT WEEK. THIS WOULD LEAN TOWARD A MORE MODERATING TREND...AND NOT SO COLD. ..JLT.. && .AVIATION.../18Z TAF ISSUANCE/ MAIN ISSUE THIS TAF PERIOD IS WHAT WILL HAPPEN WITH EXPANSIVE STRATUS DECK IN PLACE. SFC RIDGE AXIS IS CURRENTLY FROM NEAR SIOUX FALLS TO BISMARK...WITH CONDS MAINLY VFR WEST OF THIS AXIS. THE RIDGE WILL SLIDE ACROSS THE MPX AREA TONIGHT...WHICH WOULD IMPLY SKIES SHOULD CLEAR OUT FROM WEST TO EAST...BUT THIS IS LOOKING LIKE A SCENARIO WHERE LOW LEVEL MOISTURE GETS TRAPPED BENEATH THE INVERSION AND IT TAKES A NEW ROUND OF SOLAR MIXING THURSDAY MORNING TO FINALLY BLAST THE LOW CLOUDS OUT. THIS IS THE SCENARIO THE HRRR PLAYS OUT AND IN GENERAL WHAT WAS FOLLOWED FOR THESE TAFS. ONE THING TO WATCH CLOSELY THOUGH THIS AFTERNOON IS WHAT HAPPENS TO THE HOLE IN STRATUS OVER WRN WI...IF THIS CAN EXPAND SOME THIS AFTERNOON...THEN THERE IS A GOOD CHANCE THAT SKIES WILL STAY CLEAR ACROSS ERN TERMINALS. IF THIS HAPPENS...THEN RNH/EAU WILL LIKELY HAVE TO WORRY ABOUT FOG IN THE MORNING. KMSP...CONFIDENCE IN OPTIMISTIC SKY FORECAST THIS EVENING IS LOW. GOING VFR AT 4Z WILL WORK OUT...SO LONG AS THE CLEARING TO THE EAST CAN EXPAND AND SUSTAIN ITSELF. HOWEVER...COULD VERY WELL SEE THIS NOT HAPPENING...WITH CIGS REMAINING BETWEEN 020 AND 025 UNTIL AFTER 12Z THU...WITH THE POTENTIAL FOR GOING BELOW 017 LATE TONIGHT. FOR WIND DIRECTION...THE SWITCH TOWARD THE SE WILL HAPPEN OVERNIGHT. WITH SPEEDS UNDER 7 KTS...SHOULD GIVE SOME LEE WAY IN RUNWAY CONFIG. BY THU MORNING THOUGH...BOTH NAM/GFS SHOW SE WINDS INCREASING IN INTENSITY...SO WILL MOST LIKELY HAVE TO START TOMORROW ON THE 12S. /OUTLOOK FOR KMSP/ FRI...VFR. MVFR CIGS WITH CHANCE OF FZRA/RA LATE FRI NIGHT. SE WIND 5-10 KTS. SAT...IFR OR LOWER WITH CHANCE OF FZRA/RA. WINDS E 5 KTS. SUN...MVFR WITH CHANCE OF -SN EARLY. WINDS N 10-15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ JLT/MPG
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1054 AM CST WED MAR 6 2013 .SHORT TERM...(THROUGH LATE THIS AFTERNOON) ISSUED AT 332 AM CST WED MAR 6 2013 STILL SEEING SOME WEAK BANDING ON RADAR THIS MORNING THAT IS CORRESPONDING WITH THE FLURRIES BEING REPORTED IN THE SURFACE OBSERVATIONS. THIS BANDING LOOKS TO BE SET UP UNDER THE CHANNELED VORT MAX ON THE WESTERN SIDE OF THE VORT. RAP DEPICTS THAT THIS VORT WILL MOVE EAST OF THE AREA BY LATE MORNING...SO WILL MAINTAIN SCT FLURRIES OVER THE EASTERN HALF OF THE CWA THROUGH MID MORNING. SATELLITE STILL SHOWS EXTENSIVE CLOUDINESS OVER MO/IL EARLY THIS MORNING...WITH THE BACK EDGE OF THE CLOUDINESS MOVING A BIT TO THE WEST OVER WESTERN MO/EASTERN KS THE PAST FEW HOURS. THERE HAS BEEN SOME BREAKS SEEN OVER EASTERN IA WHICH IS COMPLICATING THE CLOUD FORECAST...THOUGH THESE BREAKS MAY FILL BACK IN DURING THE DAY AS MOIST LOW LEVEL CYCLONIC FLOW REMAINS OVER THE AREA. IT WILL TAKE MOST OF THE DAY BEFORE THE LOW LEVEL RIDGE CAN MOVE EAST INTO THE AREA...SO INCREASED CLOUD COVER FOR THE DAY. CONSEQUENTLY...DO NOT EXPECT MUCH OF A TEMPERATURE RECOVERY GIVEN THE CLOUDS AND NORTHWESTERLY FLOW OFF THE LINGERING SNOW PACK. BRITT && .LONG TERM...(TONIGHT THROUGH TUESDAY) ISSUED AT 332 AM CST WED MAR 6 2013 UNSEASONABLY COLD WEATHER IS EXPECTED TGT WITH GOOD RADIATIONAL COOLING AS THE SKY SHOULD CLEAR OUT AND THE SFC WIND SHOULD BECOME LIGHT AS THE SFC RIDGE AXIS WILL BE RIGHT OVER THE FORECAST AREA BY 12Z THU. SFC DEW POINTS WILL ALSO BE QUITE LOW IN THE UPPER TEENS TO LOWER 20S...PLUS PARTS OF NERN AND CNTRL MO AND W CNTRL IL WILL STILL HAVE SNOW COVER. A WARMING TREND WILL BEGIN ON THU AS AN UPPER LEVEL RIDGE OVER THE PLAINS MOVES EWD TO OVER MO BY 00Z FRI...AND THE SFC WINDS BECOME SELY OVER A PORTION OF THE AREA AS THE SFC RIDGE MOVES EAST OF THE REGION. TEMPERATURES ON FRI SHOULD BE AT OR ABOVE NORMAL WITH A RELATIVELY STRONG UPPER LEVEL RIDGE OVER MO AND IL...AND SLY LOW LEVEL WINDS BRINGING WARMER 850 MB TEMPERATURES NWD INTO OUR AREA. SHOWERS MAY MOVE INTO PORTIONS OF NERN AND CNTRL MO AS EARLY AS SAT AS A SLY LOW LEVEL JET BRINGS INCREASING LOW LEVEL WAA AND MOISTURE INTO THIS AREA WELL AHEAD OF THE UPPER LEVEL LOW AND ASSOCIATED SFC LOW MOVING EWD FROM THE SRN ROCKIES INTO THE SRN PLAINS. THE GFS MODEL IS A LITTLE QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD MOVE INTO MUCH OF THE FORECAST AREA ON SAT NGT. WILL LEAN TOWARD THE SLOWER SOLUTION OF THE ECMWF MODEL WHICH HAS ABOVE NORMAL TEMPERATURES CONTINUING ON SUN WITH THE COLD FRONT MOVING ONLY SLOWLY SEWD THROUGH OUR AREA AS THE UPPER LEVEL LOW REMAINS CLOSED OFF AND W OF OUR AREA. COLDER AIR SHOULD ADVECT SEWD INTO THE REGION SUN NGT BEHIND THE SFC LOW AND TRAILING COLD FRONT WITH THE RAIN POSSIBLY CHANGING TO SNOW ACROSS PORTIONS OF NERN AND CNTRL MO AS WELL AS W CNTRL IL. COLDER...BELOW NORMAL TEMPERATURES SHOULD OCCUR ON MONDAY WITH LINGERING SNOW POSSIBLE AS THE UPPER LEVEL LOW/TROUGH AND ASSOCIATED SFC LOW SHIFT E OF OUR AREA WITH STRONG CAA LIKELY ON THE BACKSIDE. GKS && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1049 AM CST WED MAR 6 2013 THE MVFR STRATUS WILL CONTINUE TO LIFT AND THIN THIS AFTERNOON AS HIGH PRESSURE EDGES EAST INTO MISSOURI. CLEARING TREND SHOULD CONTINUE INTO THE EVENING WITH MOSTLY CLEAR CONDITIONS OVERNIGHT AND THURSDAY. PRESSURE GRADIENT BEGINNING TO RELAX ACROSS THE REGION WITH NORTHWEST WIND DECREASING AND BECOMING LIGHT TONIGHT. SPECIFICS FOR KSTL... MVFR STRATUS WILL LIFT TO VFR THIS AFTERNOON AND THEN SCT BY EVENING. CLEAR CONDITIONS WITH LIGHT AND VARIABLE WIND OVERNIGHT. CVKING && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
511 AM CST WED MAR 6 2013 .SHORT TERM...(THROUGH LATE THIS AFTERNOON) ISSUED AT 332 AM CST WED MAR 6 2013 STILL SEEING SOME WEAK BANDING ON RADAR THIS MORNING THAT IS CORRESPONDING WITH THE FLURRIES BEING REPORTED IN THE SURFACE OBSERVATIONS. THIS BANDING LOOKS TO BE SET UP UNDER THE CHANNELED VORT MAX ON THE WESTERN SIDE OF THE VORT. RAP DEPICTS THAT THIS VORT WILL MOVE EAST OF THE AREA BY LATE MORNING...SO WILL MAINTAIN SCT FLURRIES OVER THE EASTERN HALF OF THE CWA THROUGH MID MORNING. SATELLITE STILL SHOWS EXTENSIVE CLOUDINESS OVER MO/IL EARLY THIS MORNING...WITH THE BACK EDGE OF THE CLOUDINESS MOVING A BIT TO THE WEST OVER WESTERN MO/EASTERN KS THE PAST FEW HOURS. THERE HAS BEEN SOME BREAKS SEEN OVER EASTERN IA WHICH IS COMPLICATING THE CLOUD FORECAST...THOUGH THESE BREAKS MAY FILL BACK IN DURING THE DAY AS MOIST LOW LEVEL CYCLONIC FLOW REMAINS OVER THE AREA. IT WILL TAKE MOST OF THE DAY BEFORE THE LOW LEVEL RIDGE CAN MOVE EAST INTO THE AREA...SO INCREASED CLOUD COVER FOR THE DAY. CONSEQUENTLY...DO NOT EXPECT MUCH OF A TEMPERATURE RECOVERY GIVEN THE CLOUDS AND NORTHWESTERLY FLOW OFF THE LINGERING SNOW PACK. BRITT && .LONG TERM...(TONIGHT THROUGH TUESDAY) ISSUED AT 332 AM CST WED MAR 6 2013 UNSEASONABLY COLD WEATHER IS EXPECTED TGT WITH GOOD RADIATIONAL COOLING AS THE SKY SHOULD CLEAR OUT AND THE SFC WIND SHOULD BECOME LIGHT AS THE SFC RIDGE AXIS WILL BE RIGHT OVER THE FORECAST AREA BY 12Z THU. SFC DEW POINTS WILL ALSO BE QUITE LOW IN THE UPPER TEENS TO LOWER 20S...PLUS PARTS OF NERN AND CNTRL MO AND W CNTRL IL WILL STILL HAVE SNOW COVER. A WARMING TREND WILL BEGIN ON THU AS AN UPPER LEVEL RIDGE OVER THE PLAINS MOVES EWD TO OVER MO BY 00Z FRI...AND THE SFC WINDS BECOME SELY OVER A PORTION OF THE AREA AS THE SFC RIDGE MOVES EAST OF THE REGION. TEMPERATURES ON FRI SHOULD BE AT OR ABOVE NORMAL WITH A RELATIVELY STRONG UPPER LEVEL RIDGE OVER MO AND IL...AND SLY LOW LEVEL WINDS BRINGING WARMER 850 MB TEMPERATURES NWD INTO OUR AREA. SHOWERS MAY MOVE INTO PORTIONS OF NERN AND CNTRL MO AS EARLY AS SAT AS A SLY LOW LEVEL JET BRINGS INCREASING LOW LEVEL WAA AND MOISTURE INTO THIS AREA WELL AHEAD OF THE UPPER LEVEL LOW AND ASSOCIATED SFC LOW MOVING EWD FROM THE SRN ROCKIES INTO THE SRN PLAINS. THE GFS MODEL IS A LITTLE QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD MOVE INTO MUCH OF THE FORECAST AREA ON SAT NGT. WILL LEAN TOWARD THE SLOWER SOLUTION OF THE ECMWF MODEL WHICH HAS ABOVE NORMAL TEMPERATURES CONTINUING ON SUN WITH THE COLD FRONT MOVING ONLY SLOWLY SEWD THROUGH OUR AREA AS THE UPPER LEVEL LOW REMAINS CLOSED OFF AND W OF OUR AREA. COLDER AIR SHOULD ADVECT SEWD INTO THE REGION SUN NGT BEHIND THE SFC LOW AND TRAILING COLD FRONT WITH THE RAIN POSSIBLY CHANGING TO SNOW ACROSS PORTIONS OF NERN AND CNTRL MO AS WELL AS W CNTRL IL. COLDER...BELOW NORMAL TEMPERATURES SHOULD OCCUR ON MONDAY WITH LINGERING SNOW POSSIBLE AS THE UPPER LEVEL LOW/TROUGH AND ASSOCIATED SFC LOW SHIFT E OF OUR AREA WITH STRONG CAA LIKELY ON THE BACKSIDE. GKS && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z THURSDAY MORNING) ISSUED AT 510 AM CST WED MAR 6 2013 LARGE AREA OF CLOUDS STILL COVERS MOST OF MO/IL...THOUGH THERE IS A LARGE BREAK THAT HAS DEVELOPED THE PAST FEW HOURS OVER SOUTHEAST IA/NORTHERN IL. THIS IS TIMED TO REACH KUIN AROUND 12Z AND THE ST. METRO TAF SITES AROUND 15Z. LOW LEVELS OF THE ATMOSPHERE REMAIN VERY MOIST...SO THINK THAT THIS HOLE WILL LIKELY FILL BACK IN...SO HAVE STAYED WITH PREDOMINANT CEILINGS OF 020-030 WITH TEMPO GROUPS REFLECTING THE VFR CONDITIONS. WHILE IT WILL LIKELY TAKE UNTIL LATE AFTERNOON/EVENING BEFORE THE CLOUDS CLEAR OUT OF THE AREA... SHOULD SEE CIGS CLIMB ABOVE 3000FT BY EARLY AFTERNOON. NORTHWEST WINDS WILL GUST INTO THE 25KT RANGE EARLY THIS MORNING... BUT WILL THEN DECREASE THROUGH THE DAY AS A LOW LEVEL RIDGE MOVES INTO THE AREA FROM THE WEST. THERE IS SOME POTENTIAL THAT SOME FOG MAY DEVELOP WITHIN THE RIDGE AXIS LATE TONIGHT...PARTICULARLY AT KCOU WHERE SOME SNOW REMAINS ON THE GROUND. CONFIDENCE IS NOT HIGH ENOUGH TO INCLUDE IT IN THIS TAF ISSUANCE. SPECIFICS FOR KSTL...AREA OF CLEARING OVER SOUTHEAST IA/WEST CENTRAL IL IS TIMED TO REACH THE TERMINAL AROUND 15Z. STILL THINK THAT LOW LEVELS OF THE ATMOSPHERE ARE MOIST ENOUGH FOR THE AREA OF CLEARING TO FILL BACK IN THIS MORNING...SO ONLY USED A TEMPO GROUP TO REFLECT IT. CEILINGS WILL LIKELY INCREASE TO VFR BY THIS AFTERNOON. WINDS WILL SLOWLY DECREASE TODAY BEFORE BECOMING LIGHT TONIGHT AS A LOW LEVEL RIDGE AXIS MOVES ACROSS THE AREA. BRITT && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS ST LOUIS MO
345 AM CST WED MAR 6 2013 .SHORT TERM...(THROUGH LATE THIS AFTERNOON) ISSUED AT 332 AM CST WED MAR 6 2013 STILL SEEING SOME WEAK BANDING ON RADAR THIS MORNING THAT IS CORRESPONDING WITH THE FLURRIES BEING REPORTED IN THE SURFACE OBSERVATIONS. THIS BANDING LOOKS TO BE SET UP UNDER THE CHANNELED VORT MAX ON THE WESTERN SIDE OF THE VORT. RAP DEPICTS THAT THIS VORT WILL MOVE EAST OF THE AREA BY LATE MORNING...SO WILL MAINTAIN SCT FLURRIES OVER THE EASTERN HALF OF THE CWA THROUGH MID MORNING. SATELLITE STILL SHOWS EXTENSIVE CLOUDINESS OVER MO/IL EARLY THIS MORNING...WITH THE BACK EDGE OF THE CLOUDINESS MOVING A BIT TO THE WEST OVER WESTERN MO/EASTERN KS THE PAST FEW HOURS. THERE HAS BEEN SOME BREAKS SEEN OVER EASTERN IA WHICH IS COMPLICATING THE CLOUD FORECAST...THOUGH THESE BREAKS MAY FILL BACK IN DURING THE DAY AS MOIST LOW LEVEL CYCLONIC FLOW REMAINS OVER THE AREA. IT WILL TAKE MOST OF THE DAY BEFORE THE LOW LEVEL RIDGE CAN MOVE EAST INTO THE AREA...SO INCREASED CLOUD COVER FOR THE DAY. CONSEQUENTLY...DO NOT EXPECT MUCH OF A TEMPERATURE RECOVERY GIVEN THE CLOUDS AND NORTHWESTERLY FLOW OFF THE LINGERING SNOW PACK. BRITT && .LONG TERM...(TONIGHT THROUGH TUESDAY) ISSUED AT 332 AM CST WED MAR 6 2013 UNSEASONABLY COLD WEATHER IS EXPECTED TGT WITH GOOD RADIATIONAL COOLING AS THE SKY SHOULD CLEAR OUT AND THE SFC WIND SHOULD BECOME LIGHT AS THE SFC RIDGE AXIS WILL BE RIGHT OVER THE FORECAST AREA BY 12Z THU. SFC DEW POINTS WILL ALSO BE QUITE LOW IN THE UPPER TEENS TO LOWER 20S...PLUS PARTS OF NERN AND CNTRL MO AND W CNTRL IL WILL STILL HAVE SNOW COVER. A WARMING TREND WILL BEGIN ON THU AS AN UPPER LEVEL RIDGE OVER THE PLAINS MOVES EWD TO OVER MO BY 00Z FRI...AND THE SFC WINDS BECOME SELY OVER A PORTION OF THE AREA AS THE SFC RIDGE MOVES EAST OF THE REGION. TEMPERATURES ON FRI SHOULD BE AT OR ABOVE NORMAL WITH A RELATIVELY STRONG UPPER LEVEL RIDGE OVER MO AND IL...AND SLY LOW LEVEL WINDS BRINGING WARMER 850 MB TEMPERATURES NWD INTO OUR AREA. SHOWERS MAY MOVE INTO PORTIONS OF NERN AND CNTRL MO AS EARLY AS SAT AS A SLY LOW LEVEL JET BRINGS INCREASING LOW LEVEL WAA AND MOISTURE INTO THIS AREA WELL AHEAD OF THE UPPER LEVEL LOW AND ASSOCIATED SFC LOW MOVING EWD FROM THE SRN ROCKIES INTO THE SRN PLAINS. THE GFS MODEL IS A LITTLE QUICKER WITH THIS STORM SYSTEM THAN THE ECMWF MODEL. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD MOVE INTO MUCH OF THE FORECAST AREA ON SAT NGT. WILL LEAN TOWARD THE SLOWER SOLUTION OF THE ECMWF MODEL WHICH HAS ABOVE NORMAL TEMPERATURES CONTINUING ON SUN WITH THE COLD FRONT MOVING ONLY SLOWLY SEWD THROUGH OUR AREA AS THE UPPER LEVEL LOW REMAINS CLOSED OFF AND W OF OUR AREA. COLDER AIR SHOULD ADVECT SEWD INTO THE REGION SUN NGT BEHIND THE SFC LOW AND TRAILING COLD FRONT WITH THE RAIN POSSIBLY CHANGING TO SNOW ACROSS PORTIONS OF NERN AND CNTRL MO AS WELL AS W CNTRL IL. COLDER...BELOW NORMAL TEMPERATURES SHOULD OCCUR ON MONDAY WITH LINGERING SNOW POSSIBLE AS THE UPPER LEVEL LOW/TROUGH AND ASSOCIATED SFC LOW SHIFT E OF OUR AREA WITH STRONG CAA LIKELY ON THE BACKSIDE. GKS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1150 PM CST TUE MAR 5 2013 ABUNDANT HI-END MVFR/LO-END VFR CIGS COVERING THE ENTIRE BI-STATE REGION AND SHOW NO SIGN OF ABATEMENT. SOME BREAKS HAVE DEVELOPED WAY UPSTREAM IN NERN IA AND MN...BUT WILL TAKE QUITE SOME TIME TO WORK DOWN INTO OUR AREA AND CLOUDS HAVE SHOWN SIGNS OF ATTEMPTING TO FILL THESE BREAKS OVER THE PAST COUPLE HOURS...SO FOR NOW WILL KEEP LO CIGS GOING CENTERED AROUND 3KFT. THESE CLOUDS SHOULD STICK WITH US THRU MUCH OF THE DAY ON WEDNESDAY BEFORE FINALLY BREAKING UP OR MOVING OFF TO THE E WITH ADVANCE OF SFC RIDGE WEDNESDAY EVENING. LAST GASP OF SNOW MOVING THRU STL METRO AND APPEARS IT MAY BE WITH US FOR A FEW MORE HOURS SO HAVE EXTENDED MENTION THRU 09Z. OTHERWISE...NW GUSTY SFC WINDS WILL ALSO SLOWLY DIMINISH BUT MAY NOT GET COMPLETELY LOST UNTIL LATE WEDNESDAY MORNING. SPECIFICS FOR KSTL...CIGS CENTERED AROUND 3KFT WILL BE THE RULE THRU WEDNESDAY AFTERNOON BEFORE BREAKING UP OR MOVING OFF TO THE E EARLY WEDNESDAY EVENING...VSBY DROPS FROM SNOW SHOULD BE MINIMAL FROM HERE ON OUT AND ONLY HAVE TO 5SM IN TAF THRU 09Z...NW GUSTY SFC WNDS WILL DIMINISH LATE. TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1150 PM CST TUE MAR 5 2013 .UPDATE... ISSUED AT 640 PM CST TUE MAR 5 2013 THE GOING FORECAST LOOKS TO BE GENERALLY ON TRACK. HAVE MADE A FEW UPDATES TO BUMP POPS UP THIS EVENING AS THE BAND OF SNOW CURRENTLY JUST SOUTH OF THE STL METRO. OTHER THAN THAT...HAVE ADDED IN CHANCE FOR FLURRIES EVERYWHERE FOR THE OVERNIGHT AS THE RUC KEEPS AN ELONGATED BAND OF VORTICITY OVER THE AREA AND LITTLE POCKETS OF FRONTOGENESIS. EXPLICIT MODELS ALSO SHOW SOME LIGHT PRECIPITATION CONTINUING TO ROTATE AROUND THE UPPER SYSTEM AS WELL. CARNEY && .SHORT TERM...(THROUGH LATE TONIGHT) ISSUED AT 322 PM CST TUE MAR 5 2013 WITH LITTLE IN THE WAY OF ADDITIONAL SN EXPECTED THRU TONIGHT...WILL CANCEL THE ADVISORY SOON. AREA OF SN MOVING INTO NWRN PORTIONS OF THE CWA JUST AHEAD OF THE UPPER LOW. THIS SN WILL CONTINUE TO MOVE SEWD INTO THE EVENING HOURS. AN ADDITIONAL HALF INCH...MAYBE UP TO AN INCH...CAN BE EXPECTED. WITH CLOUDS EXPECTED TO PERSIST THRU TONIGHT...HAVE TEMPS LOWER SLIGHTLY OVERNIGHT. WINDS WILL CONTINUE TO BE STRONG WITH GUSTS IN THE 20 TO 30 KT RANGE INTO THE EVE. CAN NOT RULE OUT A COUPLE OF SITES BRIEFLY REACHING WIND ADV CRITERIA...BUT EXPECT WINDS TO STAY BELOW CRITERIA. && .LONG TERM...(WEDNESDAY THROUGH NEXT TUESDAY) ISSUED AT 240 PM CST TUE MAR 5 2013 (WEDNESDAY THROUGH THURSDAY) CYCLONIC FLOW WILL CONTINUE ACROSS THE REGION THROUGH MIDDAY WEDNESDAY IN THE WAKE OF THE DEPARTING SYSTEM. BELIEVE THERE WILL BE QUITE A BIT OF RESIDUAL STRATUS AT DAYBREAK...AND WHILE THIS WILL CLEAR/DECREASE SOUTHEASTWARD DURING THE MORNING/EARLY AFTERNOON...THERE WILL ALSO BE A TENDENCY FOR ADDITIONAL STRATOCU TO DEVELOP WITH HEATING. WITH THIS IN MIND I HAVE SHADED MY TEMPERATURES TOWARDS THE COOLER MET GUIDANCE. IT WILL ALSO REMAIN BREEZY ACROSS FAR EASTERN MO INTO WESTERN ILLINOIS THROUGH THE EARLY AFTERNOON...THEN WINDS SHOULD DIMINISH AS SURFACE HIGH PRESSURE SETTLES INTO THE AREA. THE SURFACE HIGH/RIDGE WILL DOMINATE THE AREA ON WEDNESDAY NIGHT LEADING TO SEASONABLY COLD CONDITIONS. WE BEGIN THE TEMPERATURE MODERATION ON THURSDAY AS THE SURFACE HIGH SLOWLY RETREATS TO THE EAST AND HEIGHTS ALOFT RISE...HOWEVER HIGHS WILL STILL REMAIN BELOW AVERAGE. (FRIDAY INTO TUESDAY) THE WARM-UP SHOULD CONTINUE TO UNFOLD ON FRIDAY AND INTO THE WEEKEND AS THE UPPER AIR PATTERN CONTINUES TO AMPLIFY AND THE UPPER RIDGE BUILDS THROUGH THE MS VALLEY AND SHIFTS EASTWARD. THERE IS BETTER AGREEMENT IN THE EVOLVING PATTERN AND HANDLING OF THE WESTERN UPPER LOW/TROF WITH THE 12Z NWP SUITE THAN THE 00Z GUIDANCE. THE GENERAL CONSENSUS NOW IS THE INCREASINGLY POSITIVELY TILTED UPPER TROF WILL SHIFT INTO THE NATIONS MIDSECTION BY SUNDAY WITH THE UPPER LOW EJECTING NEWD THROUGH THE MID MS VALLEY SUNDAY NIGHT INTO EARLY MONDAY. THIS SHOULD BRING A GOOD RAIN THREAT TO THE REGION LATE SATURDAY NIGHT INTO SUNDAY NIGHT. THERE ARE NOW SOME SUGGESTIONS THAT THERE COULD BE A CHANGEOVER FROM RAIN TO SNOW ACROSS PARTS OF NORTHERN MISSOURI LATE SUNDAY NIGHT AND POSSIBLY POTENTIAL FOR SOME LIGHT ACCUMULATIONS...HOWEVER THE MODELS HAVE BEEN QUITE CHAOTIC WITH THE DETAILS OF THIS SYSTEM AND THUS CONFIDENCE IS LOW ON THIS ASPECT OF THE SYSTEM. GLASS && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1150 PM CST TUE MAR 5 2013 ABUNDANT HI-END MVFR/LO-END VFR CIGS COVERING THE ENTIRE BI-STATE REGION AND SHOW NO SIGN OF ABATEMENT. SOME BREAKS HAVE DEVELOPED WAY UPSTREAM IN NERN IA AND MN...BUT WILL TAKE QUITE SOME TIME TO WORK DOWN INTO OUR AREA AND CLOUDS HAVE SHOWN SIGNS OF ATTEMPTING TO FILL THESE BREAKS OVER THE PAST COUPLE HOURS...SO FOR NOW WILL KEEP LO CIGS GOING CENTERED AROUND 3KFT. THESE CLOUDS SHOULD STICK WITH US THRU MUCH OF THE DAY ON WEDNESDAY BEFORE FINALLY BREAKING UP OR MOVING OFF TO THE E WITH ADVANCE OF SFC RIDGE WEDNESDAY EVENING. LAST GASP OF SNOW MOVING THRU STL METRO AND APPEARS IT MAY BE WITH US FOR A FEW MORE HOURS SO HAVE EXTENDED MENTION THRU 09Z. OTHERWISE...NW GUSTY SFC WINDS WILL ALSO SLOWLY DIMINISH BUT MAY NOT GET COMPLETELY LOST UNTIL LATE WEDNESDAY MORNING. SPECIFICS FOR KSTL...CIGS CENTERED AROUND 3KFT WILL BE THE RULE THRU WEDNESDAY AFTERNOON BEFORE BREAKING UP OR MOVING OFF TO THE E EARLY WEDNESDAY EVENING...VSBY DROPS FROM SNOW SHOULD BE MINIMAL FROM HERE ON OUT AND ONLY HAVE TO 5SM IN TAF THRU 09Z...NW GUSTY SFC WNDS WILL DIMINISH LATE. TES && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS HASTINGS NE
356 PM CST WED MAR 6 2013 .SHORT TERM...(TONIGHT THROUGH THURSDAY) ISSUED AT 353 PM CST WED MAR 6 2013 TONIGHT THROUGH MONDAY. BIGGEST CHALLENGE WILL BE DETERMINING SKY COVER AND VISIBILITY FOR TONIGHT INTO EARLY THURSDAY MORNING. THE STRATUS THAT STUCK AROUND AND RETROGRADED WESTWARD INTO THE EASTERN HALF OF THE CWA HAS LONG MIXED OUT...WITH ONLY SOME CIRRUS MAKING ITS WAY INTO OUR CWA FROM THE SOUTH/SOUTHWEST. SATELLITE AND WATER VAPOR REVEAL SPLIT FLOW IN UPPER LEVELS...PLACING OUR CWA BETWEEN. THE SURFACE RIDGE CONTINUES TO TREK EAST...WHICH WILL EVENTUALLY TURN WIND TO A MORE SE TO S/SE WIND DIRECTION. MODELS ARE STILL KEYING IN ON SOME POSSIBLE STRATUS/FOG IN THE WESTERN CWA OVERNIGHT AND INTO THURSDAY MORNING...AND WITH THIS CONSISTENT SIGNAL...HAVE LEFT IN THE FOG FROM THE PREVIOUS FORECAST AND EXPANDED THIS A LITTLE FARTHER TO THE WEST. THE RAP IS PICKING UP SOME INCREASED STRATUS IN THE WEST AND EVENTUALLY NORTH AS A LOW-LEVEL JET INCREASED DURING THE OVERNIGHT. THE NMM ALSO INDICATES SOME INCREASE STRATUS OVERNIGHT...BUT OVER A LARGER PORTION OF THE CWA. CONFIDENCE REMAINS LOW FOR SKY COVER TONIGHT AS MODELS DO NOT HAVE A GREAT HANDLE ON LOW-LEVEL SKY COVER AND FRANKLY...HAVE NOT DONE THAT GREAT FOR AWHILE. THE NAM ADVERTISES SOME LIGHT QPF IN THE NORTHERN CWA...SOMEWHAT NEAR THE NOSE OF THE MODEST LOW-LEVEL JET DEVELOPING TONIGHT. WITH SUCH A DRY PROFILE...I DOUBT IF THERE IS MUCH CHANCE AT ALL OF MEASURABLE PRECIPITATION...ALTHOUGH THIS COULD BE AN INDICATOR OF SOME DEVELOPING STRATUS...WHICH SEEMS TO BE SUPPORTED BY THE USING RECENT VERIFICATION STATISTICS...I MADE SOME MINOR CHANGES TO TEMPERATURES FOR TONIGHT AND THURSDAY...WITH THE REMAINING SNOWPACK IN THE WESTERN CWA STILL HAVING SOME INFLUENCE WITH HIGH TEMPERATURES THURSDAY. THIS SNOWPACK MAY HAVE LIMITED EFFECT ON THE VISIBILITY FOR OVERNIGHT TONIGHT INTO THURSDAY MORNING AS WELL. .LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY) ISSUED AT 353 PM CST WED MAR 6 2013 THURSDAY NIGHT THROUGH WEDNESDAY. MAIN FORECAST CONCERNS ARE PRECIPITATION FRIDAY NIGHT THROUGH SUNDAY NIGHT AND TEMPERATURES THROUGH THE PERIOD. AN UPPER LEVEL RIDGE WILL MOVE THROUGH THE AREA THURSDAY NIGHT INTO FRIDAY. THERE IS WARM ADVECTION ACROSS THE AREA AND TEMPERATURES SHOULD BE WARMER. IN ADDITION...THE SOUTH WINDS INCREASE THE MOISTURE ACROSS THE AREA AND CLOUDS WILL INCREASE. A COUPLE OF THE MODELS HAVE STARTED SHOWING SOME LIGHT QPF ASSOCIATED WITH THE WARM ADVECTION. HAVE KEPT THE FORECAST DRY FOR NOW AND WILL WAIT FOR FURTHER RUNS. BY FRIDAY NIGHT AN UPPER LEVEL LOW PRESSURE SYSTEM MOVING OUT OF THE ROCKIES WILL START TO AFFECT THE AREA. PRECIPITATION SPREADS ACROSS THE AREA. WARM TEMPERATURES WILL KEEP PRECIPITATION IN THE FORM OF RAIN. THERE IS SOME WEAK INSTABILITY WITH MUCAPE UP TO 500 J/KG ACROSS THE AREA. THERE COULD BE SOME ISOLATED THUNDERSTORMS FRIDAY NIGHT INTO SATURDAY. SATURDAY WILL CONTINUE TO BE WARM AHEAD OF THE SURFACE LOW WITH SOUTHERLY WINDS. THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE TRACK OF THE UPPER LOW AS IT MOVES THROUGH THE PLAINS. AS THE UPPER LOW MOVES THROUGH THE PLAINS THE COLDER AIR MOVES INTO THE AREA FROM THE WEST. SATURDAY NIGHT THE PRECIPITATION CHANGES FROM RAIN TO SNOW IN THE WEST DURING THE EVENING THEN THE SNOW SPREADS ACROSS THE AREA DURING NIGHT. BY MORNING EXPECT SNOW IN THE NORTHWEST WITH RAIN AND SNOW FURTHER SOUTHEAST. ON SUNDAY SNOW WILL BE FOUND ACROSS MUCH OF THE AREA WITH SOME RAIN OR SNOW POSSIBLE IN THE SOUTHEAST. THE UPPER LOW WILL SLIDE TO THE EAST SUNDAY NIGHT AND PRECIPITATION WILL COME TO AN END. PRECIPITATION AMOUNTS ARE NOT VERY HIGH AND EXPECT SOME SNOW ACCUMULATIONS. SUNDAY WILL BE COLDER WITH HIGHS ONLY IN THE 30S BEHIND THE COLD FRONT. THE UPPER LOW WILL BE TO THE EAST AND THERE WILL BE NORTHWEST FLOW ACROSS THE AREA MONDAY THROUGH WEDNESDAY. THERE COULD BE SOME CLOUDS AS A FEW WEAK UPPER LEVEL WAVES MOVE THROUGH THE AREA...BUT THERE IS WARM ADVECTION AND TEMPERATURES SHOULD START TO WARM UP. DEPENDING ON HOW MUCH SNOW THERE IS SATURDAY NIGHT INTO SUNDAY THE TEMPERATURES MAY REMAIN A LITTLE COOLER FOR MONDAY...BUT WARM FOR TUESDAY AND WEDNESDAY. && .AVIATION...(FOR THE 18Z TAF THROUGH 18Z THURSDAY AFTERNOON) ISSUED AT 1159 AM CST WED MAR 6 2013 STRATUS TO THE WEST HAS HALTED THE EASTWARD PROGRESSION AND HAS BEGUN TO ERODE. IT APPEARS THAT CEILINGS SHOULD BE VFR AND THAT ANY ADDITIONAL CEILINGS SHOULD BE LIMITED TO LOCATIONS TO THE WEST FOR THE OVERNIGHT. AS FOR LLWS...IT APPEARS LESS LIKELY THAT THIS WILL BE AN ISSUE. SURFACE WIND SPEEDS SHOULD STAY UP A BIT TONIGHT AS THE LOW-LEVEL JET DEVELOPS...AND WINDS ALOFT DO NOT APPEAR TO BE QUITE AS STRONG AS ONCE SUSPECTED. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ SHORT TERM...HEINLEIN LONG TERM...JCB AVIATION...HEINLEIN
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
1210 PM CST WED MAR 6 2013 .AVIATION... 18Z TAFS FOR KOFK...KOMA AND KLNK. AREA OF LOW CLOUDS ACROSS EASTERN NEBRASKA HAD DECREASED RAPIDLY DURING THE LATE MORNING AND THIS TREND IS EXPECTED TO CONTINUE EARLY IN THE PERIOD THIS AFTERNOON. BIG QUESTION WILL BE WHETHER CLOUDS ROLL BACK IN AGAIN THIS EVENING SIMILAR TO LAST NIGHT. MAY BE SOME POTENTIAL IN EASTERN AREAS ALONG THE MISSOURI RIVER WHERE MORE EXTENSIVE CLOUDS IN PLACE ACROSS WESTERN IOWA BUT WILL KEEP VFR CONDITIONS AT ALL THREE SITES FOR NOW AND SEE HOW THINGS DEVELOP DURING THE AFTERNOON. && .PREV DISCUSSION... /ISSUED 354 AM CST WED MAR 6 2013/ DISCUSSION... MAIN FORECAST CONCERN TODAY WILL BE THE EXTENT OF LOW CLOUDS AND THE RESULTING AFFECT ON TEMPERATURES. THEN FOCUS TURNS TO SYSTEM MOVING INTO THE PLAINS FOR THE WEEKEND. AN EXPANSIVE AREA OF STRATUS CONTINUES TO MOVES SOUTH FROM THE EASTERN DAKOTAS AND CURRENTLY COVERS MOST OF THE CWA EXCEPT THE EXTREME WESTERN COUNTIES. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THESE CLOUDS AND WILL JUMP ON BOARD WITH THIS GUIDANCE...KEEPING CLOUD COVER THROUGH AT LEAST 18Z OVER A MAJORITY OF THE CWA. A SFC HIGH PRESSURE RIDGE CURRENTLY OVER CENTRAL NEBRASKA WILL CONTINUE TO BUILD EAST AND INHIBIT MIXING TO SCOUR OUT CLOUDS. THEREFORE THE RAP IDEA OF HANGING ONTO THE CLOUDS SEEMS FAIR THROUGH MUCH OF THE MORNING HOURS AND POSSIBLY INTO THE AFTERNOON IN OUR EAST. AS SOUTHERLY LOW LEVEL FLOW INCREASES LATE THIS AFTERNOON...EXPECT CLOUDS TO MOVE OUT FROM WEST TO EAST. HAVE REDUCED HIGHS TO A FEW DEGREES BELOW MOS DUE TO CLOUD COVER. QUIET CONDITIONS AND A GRADUAL WARMING TREND ARE EXPECTED TODAY THROUGH FRIDAY AS AN UPPER RIDGE PASSES OVER THE CENTRAL CONUS THROUGH THIS TIME PERIOD. HIGH TEMPS SHOULD BE IN THE UPPER 40S AND LOWER 50S BY FRIDAY. FOCUS TURNS TO LARGE SYSTEM CURRENTLY OFF THE PACIFIC NORTHWEST COAST. THIS IS FORECAST TO ROUND THE FOUR CORNERS REGION BY SATURDAY 12Z. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON PLACEMENT AND TIMING LEADING TO INCREASING FORECASTER CONFIDENCE. A LEAD SHORTWAVE WILL EJECT INTO THE CENTRAL PLAINS BY FRIDAY NIGHT WITH A SFC WARM FRONT EXTENDING NORTHEAST AND BISECTING OUR CWA. THIS BOUNDARY SHOULD BE THE FOCUS FOR PRECIPITATION FRIDAY NIGHT INTO SATURDAY. BETTER UPPER LEVEL DYNAMICS WILL ADVANCE INTO THE AREA SATURDAY NIGHT INTO SUNDAY AS THE UPPER LOW KICKS OUT OF EASTERN COLORADO AND INTO KANSAS. WILL CONTINUE LIKELY POPS FOR THIS TIME PERIOD. TIGHT BAROCLINIC ZONE WILL REMAIN EXTENDED ACROSS THE FORECAST AREA WITH SNOW MOST LIKELY TO THE NORTH OF THE BOUNDARY AND RAIN IN THE SOUTH...WITH A TRANSITION ZONE SOMEWHERE IN THE MIDDLE. MODELS HAVE BEEN CONSISTENT WITH DROPPING COLDER AIR SOUTH OVER THE FORECAST AREA SO SNOW COULD BE PRIMARY PCPN TYPE SAT NIGHT THROUGH SUNDAY NIGHT WHEN DEFORMATION ZONE MOVES OVERHEAD. HAVE INCREASED THE SFC WINDS ON THE BACKSIDE OF THIS SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH UNIDIRECTIONAL NORTHERLY FLOW CREATING QUITE BLUSTERY CONDITIONS. 850MB WIND SPEEDS ARE FORECAST AROUND 50 KTS OFF BOTH THE 00Z GFS AND 00Z ECMWF. THIS SAID...IF ANY SNOW IS FALLING...IT WILL BE BLOWING AROUND. THIS SYSTEM QUICKLY MOVES EAST SUNDAY NIGHT ENDING PCPN FROM WEST TO EAST LEAVING NORTHWESTERLY FLOW ALOFT. FORECAST SUB ZERO C 850 MB TEMPS IN ADDITION TO POTENTIAL SNOW COVER WOULD SUGGEST BELOW NORMAL TEMPS EARLY NEXT WEEK. KERN && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ FOBERT
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
554 AM CST WED MAR 6 2013 .AVIATION... 12Z TAFS FOR KOFK...KOMA AND KLNK. LOW CLOUDS CONTINUED TO HANG TOUGH ACROSS EASTERN NEBRASKA WITH CIGS RANGING FROM JUST BELOW 1K FT AGL ON NW EDGE TO NEAR 2K FT AGL ON SERN END. ALTHOUGH WIND FLOW IS WEAK AND FAVORABLE FOR A CONTINUATION OF CIGS THROUGH MIDDAY AT LEAST...BREAKS IN OVERCAST HAVE BEEN NOTED OVR WRN IA AND NW MO WHICH LEADS TO A LOW CONFIDENCE CLOUD FORECAST. WOULD SUSPECT...HOWEVER...THAT EROSION WILL CONTINUE OR EVEN ACCELERATE AS DAYTIME HEATING COMMENCES LATER THIS MORNING. SOME REDEVELOPMENT POSSIBLE AGAIN LATER TONIGHT...ESPECIALLY AT KOFK...BUT FOR NOW KEPT CIGS OUT OF FORECAST FOR TONIGHT. CHERMOK && .PREV DISCUSSION... /ISSUED 354 AM CST WED MAR 6 2013/ DISCUSSION... MAIN FORECAST CONCERN TODAY WILL BE THE EXTENT OF LOW CLOUDS AND THE RESULTING AFFECT ON TEMPERATURES. THEN FOCUS TURNS TO SYSTEM MOVING INTO THE PLAINS FOR THE WEEKEND. AN EXPANSIVE AREA OF STRATUS CONTINUES TO MOVES SOUTH FROM THE EASTERN DAKOTAS AND CURRENTLY COVERS MOST OF THE CWA EXCEPT THE EXTREME WESTERN COUNTIES. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THESE CLOUDS AND WILL JUMP ON BOARD WITH THIS GUIDANCE...KEEPING CLOUD COVER THROUGH AT LEAST 18Z OVER A MAJORITY OF THE CWA. A SFC HIGH PRESSURE RIDGE CURRENTLY OVER CENTRAL NEBRASKA WILL CONTINUE TO BUILD EAST AND INHIBIT MIXING TO SCOUR OUT CLOUDS. THEREFORE THE RAP IDEA OF HANGING ONTO THE CLOUDS SEEMS FAIR THROUGH MUCH OF THE MORNING HOURS AND POSSIBLY INTO THE AFTERNOON IN OUR EAST. AS SOUTHERLY LOW LEVEL FLOW INCREASES LATE THIS AFTERNOON...EXPECT CLOUDS TO MOVE OUT FROM WEST TO EAST. HAVE REDUCED HIGHS TO A FEW DEGREES BELOW MOS DUE TO CLOUD COVER. QUIET CONDITIONS AND A GRADUAL WARMING TREND ARE EXPECTED TODAY THROUGH FRIDAY AS AN UPPER RIDGE PASSES OVER THE CENTRAL CONUS THROUGH THIS TIME PERIOD. HIGH TEMPS SHOULD BE IN THE UPPER 40S AND LOWER 50S BY FRIDAY. FOCUS TURNS TO LARGE SYSTEM CURRENTLY OFF THE PACIFIC NORTHWEST COAST. THIS IS FORECAST TO ROUND THE FOUR CORNERS REGION BY SATURDAY 12Z. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON PLACEMENT AND TIMING LEADING TO INCREASING FORECASTER CONFIDENCE. A LEAD SHORTWAVE WILL EJECT INTO THE CENTRAL PLAINS BY FRIDAY NIGHT WITH A SFC WARM FRONT EXTENDING NORTHEAST AND BISECTING OUR CWA. THIS BOUNDARY SHOULD BE THE FOCUS FOR PRECIPITATION FRIDAY NIGHT INTO SATURDAY. BETTER UPPER LEVEL DYNAMICS WILL ADVANCE INTO THE AREA SATURDAY NIGHT INTO SUNDAY AS THE UPPER LOW KICKS OUT OF EASTERN COLORADO AND INTO KANSAS. WILL CONTINUE LIKELY POPS FOR THIS TIME PERIOD. TIGHT BAROCLINIC ZONE WILL REMAIN EXTENDED ACROSS THE FORECAST AREA WITH SNOW MOST LIKELY TO THE NORTH OF THE BOUNDARY AND RAIN IN THE SOUTH...WITH A TRANSITION ZONE SOMEWHERE IN THE MIDDLE. MODELS HAVE BEEN CONSISTENT WITH DROPPING COLDER AIR SOUTH OVER THE FORECAST AREA SO SNOW COULD BE PRIMARY PCPN TYPE SAT NIGHT THROUGH SUNDAY NIGHT WHEN DEFORMATION ZONE MOVES OVERHEAD. HAVE INCREASED THE SFC WINDS ON THE BACKSIDE OF THIS SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH UNIDIRECTIONAL NORTHERLY FLOW CREATING QUITE BLUSTERY CONDITIONS. 850MB WIND SPEEDS ARE FORECAST AROUND 50 KTS OFF BOTH THE 00Z GFS AND 00Z ECMWF. THIS SAID...IF ANY SNOW IS FALLING...IT WILL BE BLOWING AROUND. THIS SYSTEM QUICKLY MOVES EAST SUNDAY NIGHT ENDING PCPN FROM WEST TO EAST LEAVING NORTHWESTERLY FLOW ALOFT. FORECAST SUB ZERO C 850 MB TEMPS IN ADDITION TO POTENTIAL SNOW COVER WOULD SUGGEST BELOW NORMAL TEMPS EARLY NEXT WEEK. KERN && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION
NWS OMAHA/VALLEY NE
354 AM CST WED MAR 6 2013 .DISCUSSION... MAIN FORECAST CONCERN TODAY WILL BE THE EXTENT OF LOW CLOUDS AND THE RESULTING AFFECT ON TEMPERATURES. THEN FOCUS TURNS TO SYSTEM MOVING INTO THE PLAINS FOR THE WEEKEND. AN EXPANSIVE AREA OF STRATUS CONTINUES TO MOVES SOUTH FROM THE EASTERN DAKOTAS AND CURRENTLY COVERS MOST OF THE CWA EXCEPT THE EXTREME WESTERN COUNTIES. THE RAP SEEMS TO HAVE THE BEST HANDLE ON THESE CLOUDS AND WILL JUMP ON BOARD WITH THIS GUIDANCE...KEEPING CLOUD COVER THROUGH AT LEAST 18Z OVER A MAJORITY OF THE CWA. A SFC HIGH PRESSURE RIDGE CURRENTLY OVER CENTRAL NEBRASKA WILL CONTINUE TO BUILD EAST AND INHIBIT MIXING TO SCOUR OUT CLOUDS. THEREFORE THE RAP IDEA OF HANGING ONTO THE CLOUDS SEEMS FAIR THROUGH MUCH OF THE MORNING HOURS AND POSSIBLY INTO THE AFTERNOON IN OUR EAST. AS SOUTHERLY LOW LEVEL FLOW INCREASES LATE THIS AFTERNOON...EXPECT CLOUDS TO MOVE OUT FROM WEST TO EAST. HAVE REDUCED HIGHS TO A FEW DEGREES BELOW MOS DUE TO CLOUD COVER. QUIET CONDITIONS AND A GRADUAL WARMING TREND ARE EXPECTED TODAY THROUGH FRIDAY AS AN UPPER RIDGE PASSES OVER THE CENTRAL CONUS THROUGH THIS TIME PERIOD. HIGH TEMPS SHOULD BE IN THE UPPER 40S AND LOWER 50S BY FRIDAY. FOCUS TURNS TO LARGE SYSTEM CURRENTLY OFF THE PACIFIC NORTHWEST COAST. THIS IS FORECAST TO ROUND THE FOUR CORNERS REGION BY SATURDAY 12Z. MODELS CONTINUE TO COME INTO BETTER AGREEMENT ON PLACEMENT AND TIMING LEADING TO INCREASING FORECASTER CONFIDENCE. A LEAD SHORTWAVE WILL EJECT INTO THE CENTRAL PLAINS BY FRIDAY NIGHT WITH A SFC WARM FRONT EXTENDING NORTHEAST AND BISECTING OUR CWA. THIS BOUNDARY SHOULD BE THE FOCUS FOR PRECIPITATION FRIDAY NIGHT INTO SATURDAY. BETTER UPPER LEVEL DYNAMICS WILL ADVANCE INTO THE AREA SATURDAY NIGHT INTO SUNDAY AS THE UPPER LOW KICKS OUT OF EASTERN COLORADO AND INTO KANSAS. WILL CONTINUE LIKELY POPS FOR THIS TIME PERIOD. TIGHT BAROCLINIC ZONE WILL REMAIN EXTENDED ACROSS THE FORECAST AREA WITH SNOW MOST LIKELY TO THE NORTH OF THE BOUNDARY AND RAIN IN THE SOUTH...WITH A TRANSITION ZONE SOMEWHERE IN THE MIDDLE. MODELS HAVE BEEN CONSISTENT WITH DROPPING COLDER AIR SOUTH OVER THE FORECAST AREA SO SNOW COULD BE PRIMARY PCPN TYPE SAT NIGHT THROUGH SUNDAY NIGHT WHEN DEFORMATION ZONE MOVES OVERHEAD. HAVE INCREASED THE SFC WINDS ON THE BACKSIDE OF THIS SYSTEM SATURDAY NIGHT THROUGH SUNDAY NIGHT WITH UNIDIRECTIONAL NORTHERLY FLOW CREATING QUITE BLUSTERY CONDITIONS. 850MB WIND SPEEDS ARE FORECAST AROUND 50 KTS OFF BOTH THE 00Z GFS AND 00Z ECMWF. THIS SAID...IF ANY SNOW IS FALLING...IT WILL BE BLOWING AROUND. THIS SYSTEM QUICKLY MOVES EAST SUNDAY NIGHT ENDING PCPN FROM WEST TO EAST LEAVING NORTHWESTERLY FLOW ALOFT. FORECAST SUB ZERO C 850 MB TEMPS IN ADDITION TO POTENTIAL SNOW COVER WOULD SUGGEST BELOW NORMAL TEMPS EARLY NEXT WEEK. KERN && .AVIATION...06Z TAFS FOR KOMA...KLNK AND KOFK. MVFR CEILINGS WILL LINGER AT KOMA...PERHAPS UNTIL MID TO LATE MORNING...BUT SHOULD BEGIN TO SCATTER OUT BY 1820Z. INITIAL CLOUD LINE WAS SLOWLY RETREATING WEST AND FINALLY HAD REACHED KOFK...AND WILL PROBABLY REACH KLNK BY 07-08Z. BELIEVE CLOUDS COULD SCATTER AT KOFK/KLNK BY 16-18Z. DEWALD && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1117 PM CST TUE MAR 5 2013 .SYNOPSIS... ISSUED AT 320 PM CST TUE MAR 5 2013 H5 HAND ANALYSIS THIS MORNING...INDICATES A CONTINUED ACTIVE PATTERN ACROSS NOAM. A STRONG SHORTWAVE WAS LOCATED ACROSS NWRN MISSOURI WITH DECENT HT FALLS NOTED FROM THE TWIN CITIES SWD INTO SWRN MO. FURTHER WEST...A LOW AMPLITUDE RIDGE EXTENDED FROM SO CALIFORNIA NWD TO THE IDAHO PANHANDLE. WHILE WEST OF THIS FEATURE...A TROUGH EXTENDED FROM ERN BRITISH COLUMBIA...SWD TO A CLOSED LOW OFF THE COAST OF OREGON. ACROSS THE EASTERN CONUS...A CLOSED LOW WAS PRESENT OVER THE CANADIAN MARITIMES WITH HIGH PRESSURE NOTED OVER NRN QUEBEC. AT THE SURFACE...HIGH PRESSURE HAS BUILT INTO WESTERN NEBRASKA THIS AFTERNOON RESULTING IN LIGHT WINDS. FURTHER EAST...BREEZY CONDITIONS CONTINUED. TEMPERATURES AS OF 3 PM CST RANGED FROM 32 AT O`NEILL TO 41 AT OGALLALA. && .UPDATE... ISSUED AT 1005 PM CST TUE MAR 5 2013 THE NEW NAM...GEM AND GFS CONTINUE TO ADVERTISE INCREASING LOW LEVEL MOISTURE WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT LEADING TO EITHER TO THE FORMATION OF FOG OR LOW STRATUS. MEANWHILE THE RAP13 IS DRAGGING THE STRATUS ACROSS THE MISSOURI BASIN WEST TO NEAR HIGHWAY 83 BY MORNING. IT APPEARS THE RAP IS TOO FAST. SATELLITE TIMING TOO INDICATE IT ONLY MOVING WEST AT 5KT AND WOULD MIX OUT DURING THE DAY AND PERHAPS RETURN WEDNESDAY NIGHT. THE FCST FOLLOWS NAM WITH INCREASING CLOUDS AFTER MIDNIGHT AND PATCHY FOG FORMING EAST OF HIGHWAY 61. NO DISCERNIBLE CHANGES IN THE REST OF THE SHORT TERM FORECAST EXCEPT THE MODELS ARE SHOWING HIGHER DEW PTS OVERNIGHT WHICH APPEARS TO BE VERIFYING. UPDATE ISSUED AT 701 PM CST TUE MAR 5 2013 A NEW FORECAST IS OUT. RAISED OVERNIGHT LOW TEMPS A BIT IN THE WEST WHERE A LOW LEVEL JET SHOULD KICK UP IN A FEW HOURS. LOWS AROUND 10 TO SINGLE DIGITS EAST OF HIGHWAY 83 WHERE WINDS WILL REMAIN CALM MOST OF THE NIGHT. SOUTH WINDS INCREASE TO 20 TO 30 MPH WEDNESDAY AND A BLEND OF THE NAM...GEM AND ECM INDICATED HIGHS IN THE 30S AND 40S...NO REAL CHANGE FROM THE PREVIOUS FCST. THE NAM AND GFS SUGGEST SOME CLOUDINESS MAY DEVELOP EAST OF HIGHWAY 83 IN THE AFTN AS RETURN MOISTURE DEVELOPS. EITHER FOG OR LOW CLOUDINESS DEVELOPS WEDNESDAY NIGHT WITH LOWS IN THE 20S. SOUTH WINDS CONTINUE TO RETURN MOISTURE. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 320 PM CST TUE MAR 5 2013 TEMPERATURES THIS EVENING WILL DROP QUICKLY AS A SFC HIGH PRESSURE MOVES ACROSS THE NORTHERN PLAINS. LIGHT WINDS...CLEAR SKIES...AND A RELATIVELY DRY AIRMASS WILL PROVIDE FOR EFFICIENT RADIATIVE COOLING AND LOWS IN THE LOW TO MID TEENS FOR MOST OF THE CWA. HOWEVER...AS THE SFC HIGH SLIDES EAST OF THE AREA WINDS WILL INCREASE OUT OF THE SOUTH FROM WEST TO EAST ACROSS THE CWA. THIS MAY ALLOW FOR WEAK MIXING TO OCCUR LATE IN THE OVERNIGHT TOWARD EARLY TOMORROW MORNING AND LIMIT THE PERIOD OF DIURNAL COOLING. EXPECTING OVERNIGHT LOWS TO OCCUR EARLY BEFORE HOLDING STEADY OR EVEN WARMING A FEW DEGREES BY DAY BREAK WEDNESDAY. WINDS WILL CONTINUE TO INCREASE OUT OF THE SOUTH SOUTHEAST DURING THE DAY WEDNESDAY...WITH 15 TO 25 MPH WINDS LIKELY DURING THE AFTERNOON. CLEAR SKIES WILL CONTINUE WITH DRY AIRMASS STILL IN PLACE. HIGH TEMPERATURES WILL BE LIMITED FOR THE EASTERN TWO-THIRDS OF THE CWA AS 850MB TEMPS STRUGGLE TO RECOVER. EXPECTING HIGHS ONLY IN THE 40S FOR MOST OF THE AREA...WITH 50S POSSIBLE IN THE EAST PANHANDLE AND FAR SOUTHWEST NEBRASKA. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 320 PM CST TUE MAR 5 2013 WEDNESDAY NIGHT THROUGH FRIDAY...MAIN FORECASTING CHALLENGE FOR THE LATTER HALF OF THE WORK WEEK DEALS WITH TEMPERATURES...MAINLY HIGHS ON THURSDAY AND FRIDAY AS A DEEP TROUGH OF LOW PRESSURE ALOFT DEEPENS ACROSS THE SWRN CONUS. ON THURSDAY WARMER AIR WILL PUSH INTO THE PANHANDLE AND WESTERN AREAS WITH SRLY WINDS DEVELOPING IN THE AFTERNOON HOURS. FURTHER EAST HOWEVER...LIGHT SERLY AND VARIABLE WINDS IN THE CENTRAL AND EASTERN CWA WILL LIMIT THE WARMUP TO THE UPPER 40S/LWR 50S VS. THE UPPER 50S TO NEAR 60 OUT WEST. ON THURSDAY NIGHT...A WEAK COOL FRONT WILL PUSH ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...STALLING ACROSS NRN KS AND SERN NEBRASKA. SURFACE LOW PRESSURE WILL DEEPEN FRIDAY ACROSS EASTERN COLORADO...LIFTING THE FRONT NORTH INTO SOUTH CENTRAL AND EASTERN NEBRASKA. HOWEVER...THE FRONT IS EXPECTED TO STAY OFF TO THE SOUTH OF THE FORECAST AREA FRIDAY...LEADING TO EASTERLY UPSLOPE WINDS AND HIGHS IN THE 40S. EVEN HIGHS IN THE 40S...MAY BE OVERLY OPTIMISTIC. FRIDAY NIGHT THROUGH TUESDAY...MAIN FORECASTING CHALLENGE CONTINUES TO BE PRECIPITATION AND PRECIPITATION TYPE IN ASSOCIATION WITH A DEEP TROUGH OF LOW PRESSURE...WHICH TRACKS ACROSS THE CENTRAL CONUS THIS WEEKEND. THE LATEST 12Z GFS THIS MORNING AND THE 00Z ECMWF FROM LAST NIGHT HAVE DECENT AGREEMENT WITH THE H5 LOW POSN SATURDAY AT 12Z. AFTER THIS POINT...DIFFERENCES WITH THE MODEL SOLUTIONS EMERGE...IN PARTICULAR...WHETHER THE LOW PHASES WITH THE NRN STREAM OR NOT. BY 12Z SUNDAY...THE 12Z GFS FROM THIS MORNING...PHASES THE LOW WITH THE NRN STREAM...BECOMES POSITIVELY TILTED...AND MOVES THE SYSTEM INTO THE MID MISSISSIPPI VALLEY BY MONDAY MORNING. THE ECMWF FROM LAST NIGHT...IS DISCONNECTED FROM THE NRN STREAM...NEUTRAL TILTED AND REMAINS JUST OFF TO THE SOUTH OF THE CWA THROUGH 12Z MONDAY. THE DIFFERENCES ARE HUGE IN THE AMOUNT OF QPF GENERATED BY EACH SOLUTION THROUGH TUESDAY. FOR EXAMPLE...FOR NORTH PLATTE ACCUM QPF RANGES ANYWHERE FROM 0.30 WITH THE 12Z GFS SOLN...TO 2.30 INCHES WITH THE 00Z ECMWF. THE CURRENT INHERITED FORECAST...HAS THE BEST PRECIPITATION CHANCES FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING AND WILL LEAVE THIS AS IS FOR NOW GIVEN THE TIMING UNCERTAINTIES IN THE MODELS. AS FOR PRECIPITATION TYPES...MEX AND ECE TEMPERATURES ACROSS THE SRN AND EASTERN CWA...FAVOR ALL RAIN AT THIS JUNCTURE...WITH A MIX AND ALL SNOW IN THE WESTERN PORTION OF THE CWA. IF THE MORE PROGRESSIVE GFS SOLUTION VERIFIES...SNOW AMOUNTS WILL BE MUCH LIGHTER COMPARED TO THE SLOWER 00Z EC SOLUTION. WILL TAKE A CLOSE LOOK AT THE 12Z EC SOLUTION...AND IF IT IS PROGRESSIVE LIKE THE 12Z GFS...SOME ELIMINATION OF POPS ON MONDAY AND TUESDAY MAY BE IN ORDER. IN ADDITION TO ELIMINATING POPS MONDAY AND TUESDAY...IF THE MODEL COMES IN FASTER WITH THE SYSTEM...THE THREAT FOR LARGE ACCUMULATING SNOWS AND LONG DURATION PRECIPITATION WILL BE MINIMIZED. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 1110 PM CST TUE MAR 5 2013 VFR IS EXPECTED ALL AREAS THROUGH 00Z WEDNESDAY EVENING. THEREAFTER THE FORECAST BECOMES VERY UNCERTAIN. THE ISSUE IS RAPIDLY INCREASING BOUNDARY LAYER MOISTURE AND THE DEVELOPMENT OF IFR CIGS ACROSS A GOOD PORTION OF THE FCST AREA. THE MODELS CONTINUE TO DRAG MOISTURE...CURRENTLY ACROSS THE MISSOURI BASIN WEST TOWARD HIGHWAY 83 LATE WEDNESDAY AFTERNOON LEADING TO THE FORMATION OF IFR WEDNESDAY NIGHT. THE RAP MODEL IS THE FASTEST PRODUCING IFR ALONG HIGHWAY 83 BY 12Z-14Z WHILE THE NAM...GEM AND GFS MODELS SHOW THIS FORMING AROUND 03Z WEDNESDAY EVENING. GIVEN THE UNCERTAINTIES OF THIS FEATURE THE BEST APPRAOCH WOULD BE TO WAIT FOR A DEFINITIVE SATELLITE SIGNAL LATE WEDNESDAY AND THEN MAKE THE FORECAST. SO VFR IS EXPECTED THROUGH WEDNESDAY AFTERNOON AND PRESUMABLY...SOME SIGNAL SHOULD DEVELOP AROUND 03Z-06Z WEDNESDAY EVENING. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CDC SYNOPSIS...CLB SHORT TERM...MARTIN LONG TERM...CLB AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1014 PM CST TUE MAR 5 2013 .SYNOPSIS... ISSUED AT 320 PM CST TUE MAR 5 2013 H5 HAND ANALYSIS THIS MORNING...INDICATES A CONTINUED ACTIVE PATTERN ACROSS NOAM. A STRONG SHORTWAVE WAS LOCATED ACROSS NWRN MISSOURI WITH DECENT HT FALLS NOTED FROM THE TWIN CITIES SWD INTO SWRN MO. FURTHER WEST...A LOW AMPLITUDE RIDGE EXTENDED FROM SO CALIFORNIA NWD TO THE IDAHO PANHANDLE. WHILE WEST OF THIS FEATURE...A TROUGH EXTENDED FROM ERN BRITISH COLUMBIA...SWD TO A CLOSED LOW OFF THE COAST OF OREGON. ACROSS THE EASTERN CONUS...A CLOSED LOW WAS PRESENT OVER THE CANADIAN MARITIMES WITH HIGH PRESSURE NOTED OVER NRN QUEBEC. AT THE SURFACE...HIGH PRESSURE HAS BUILT INTO WESTERN NEBRASKA THIS AFTERNOON RESULTING IN LIGHT WINDS. FURTHER EAST...BREEZY CONDITIONS CONTINUED. TEMPERATURES AS OF 3 PM CST RANGED FROM 32 AT O`NEILL TO 41 AT OGALLALA. && .UPDATE... ISSUED AT 1005 PM CST TUE MAR 5 2013 THE NEW NAM...GEM AND GFS CONTINUE TO ADVERTISE INCREASING LOW LEVEL MOISTURE WEDNESDAY AFTERNOON AND WEDNESDAY NIGHT LEADING TO EITHER TO THE FORMATION OF FOG OR LOW STRATUS. MEANWHILE THE RAP13 IS DRAGGING THE STRATUS ACROSS THE MISSOURI BASIN WEST TO NEAR HIGHWAY 83 BY MORNING. IT APPEARS THE RAP IS TOO FAST. SATELLITE TIMING TOO INDICATE IT ONLY MOVING WEST AT 5KT AND WOULD MIX OUT DURING THE DAY AND PERHAPS RETURN WEDNESDAY NIGHT. THE FCST FOLLOWS NAM WITH INCREASING CLOUDS AFTER MIDNIGHT AND PATCHY FOG FORMING EAST OF HIGHWAY 61. NO DISCERNIBLE CHANGES IN THE REST OF THE SHORT TERM FORECAST EXCEPT THE MODELS ARE SHOWING HIGHER DEW PTS OVERNIGHT WHICH APPEARS TO BE VERIFYING. UPDATE ISSUED AT 701 PM CST TUE MAR 5 2013 A NEW FORECAST IS OUT. RAISED OVERNIGHT LOW TEMPS A BIT IN THE WEST WHERE A LOW LEVEL JET SHOULD KICK UP IN A FEW HOURS. LOWS AROUND 10 TO SINGLE DIGITS EAST OF HIGHWAY 83 WHERE WINDS WILL REMAIN CALM MOST OF THE NIGHT. SOUTH WINDS INCREASE TO 20 TO 30 MPH WEDNESDAY AND A BLEND OF THE NAM...GEM AND ECM INDICATED HIGHS IN THE 30S AND 40S...NO REAL CHANGE FROM THE PREVIOUS FCST. THE NAM AND GFS SUGGEST SOME CLOUDINESS MAY DEVELOP EAST OF HIGHWAY 83 IN THE AFTN AS RETURN MOISTURE DEVELOPS. EITHER FOG OR LOW CLOUDINESS DEVELOPS WEDNESDAY NIGHT WITH LOWS IN THE 20S. SOUTH WINDS CONTINUE TO RETURN MOISTURE. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 320 PM CST TUE MAR 5 2013 TEMPERATURES THIS EVENING WILL DROP QUICKLY AS A SFC HIGH PRESSURE MOVES ACROSS THE NORTHERN PLAINS. LIGHT WINDS...CLEAR SKIES...AND A RELATIVELY DRY AIRMASS WILL PROVIDE FOR EFFICIENT RADIATIVE COOLING AND LOWS IN THE LOW TO MID TEENS FOR MOST OF THE CWA. HOWEVER...AS THE SFC HIGH SLIDES EAST OF THE AREA WINDS WILL INCREASE OUT OF THE SOUTH FROM WEST TO EAST ACROSS THE CWA. THIS MAY ALLOW FOR WEAK MIXING TO OCCUR LATE IN THE OVERNIGHT TOWARD EARLY TOMORROW MORNING AND LIMIT THE PERIOD OF DIURNAL COOLING. EXPECTING OVERNIGHT LOWS TO OCCUR EARLY BEFORE HOLDING STEADY OR EVEN WARMING A FEW DEGREES BY DAY BREAK WEDNESDAY. WINDS WILL CONTINUE TO INCREASE OUT OF THE SOUTH SOUTHEAST DURING THE DAY WEDNESDAY...WITH 15 TO 25 MPH WINDS LIKELY DURING THE AFTERNOON. CLEAR SKIES WILL CONTINUE WITH DRY AIRMASS STILL IN PLACE. HIGH TEMPERATURES WILL BE LIMITED FOR THE EASTERN TWO-THIRDS OF THE CWA AS 850MB TEMPS STRUGGLE TO RECOVER. EXPECTING HIGHS ONLY IN THE 40S FOR MOST OF THE AREA...WITH 50S POSSIBLE IN THE EAST PANHANDLE AND FAR SOUTHWEST NEBRASKA. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 320 PM CST TUE MAR 5 2013 WEDNESDAY NIGHT THROUGH FRIDAY...MAIN FORECASTING CHALLENGE FOR THE LATTER HALF OF THE WORK WEEK DEALS WITH TEMPERATURES...MAINLY HIGHS ON THURSDAY AND FRIDAY AS A DEEP TROUGH OF LOW PRESSURE ALOFT DEEPENS ACROSS THE SWRN CONUS. ON THURSDAY WARMER AIR WILL PUSH INTO THE PANHANDLE AND WESTERN AREAS WITH SRLY WINDS DEVELOPING IN THE AFTERNOON HOURS. FURTHER EAST HOWEVER...LIGHT SERLY AND VARIABLE WINDS IN THE CENTRAL AND EASTERN CWA WILL LIMIT THE WARMUP TO THE UPPER 40S/LWR 50S VS. THE UPPER 50S TO NEAR 60 OUT WEST. ON THURSDAY NIGHT...A WEAK COOL FRONT WILL PUSH ACROSS WESTERN AND NORTH CENTRAL NEBRASKA...STALLING ACROSS NRN KS AND SERN NEBRASKA. SURFACE LOW PRESSURE WILL DEEPEN FRIDAY ACROSS EASTERN COLORADO...LIFTING THE FRONT NORTH INTO SOUTH CENTRAL AND EASTERN NEBRASKA. HOWEVER...THE FRONT IS EXPECTED TO STAY OFF TO THE SOUTH OF THE FORECAST AREA FRIDAY...LEADING TO EASTERLY UPSLOPE WINDS AND HIGHS IN THE 40S. EVEN HIGHS IN THE 40S...MAY BE OVERLY OPTIMISTIC. FRIDAY NIGHT THROUGH TUESDAY...MAIN FORECASTING CHALLENGE CONTINUES TO BE PRECIPITATION AND PRECIPITATION TYPE IN ASSOCIATION WITH A DEEP TROUGH OF LOW PRESSURE...WHICH TRACKS ACROSS THE CENTRAL CONUS THIS WEEKEND. THE LATEST 12Z GFS THIS MORNING AND THE 00Z ECMWF FROM LAST NIGHT HAVE DECENT AGREEMENT WITH THE H5 LOW POSN SATURDAY AT 12Z. AFTER THIS POINT...DIFFERENCES WITH THE MODEL SOLUTIONS EMERGE...IN PARTICULAR...WHETHER THE LOW PHASES WITH THE NRN STREAM OR NOT. BY 12Z SUNDAY...THE 12Z GFS FROM THIS MORNING...PHASES THE LOW WITH THE NRN STREAM...BECOMES POSITIVELY TILTED...AND MOVES THE SYSTEM INTO THE MID MISSISSIPPI VALLEY BY MONDAY MORNING. THE ECMWF FROM LAST NIGHT...IS DISCONNECTED FROM THE NRN STREAM...NEUTRAL TILTED AND REMAINS JUST OFF TO THE SOUTH OF THE CWA THROUGH 12Z MONDAY. THE DIFFERENCES ARE HUGE IN THE AMOUNT OF QPF GENERATED BY EACH SOLUTION THROUGH TUESDAY. FOR EXAMPLE...FOR NORTH PLATTE ACCUM QPF RANGES ANYWHERE FROM 0.30 WITH THE 12Z GFS SOLN...TO 2.30 INCHES WITH THE 00Z ECMWF. THE CURRENT INHERITED FORECAST...HAS THE BEST PRECIPITATION CHANCES FROM LATE FRIDAY NIGHT THROUGH SUNDAY MORNING AND WILL LEAVE THIS AS IS FOR NOW GIVEN THE TIMING UNCERTAINTIES IN THE MODELS. AS FOR PRECIPITATION TYPES...MEX AND ECE TEMPERATURES ACROSS THE SRN AND EASTERN CWA...FAVOR ALL RAIN AT THIS JUNCTURE...WITH A MIX AND ALL SNOW IN THE WESTERN PORTION OF THE CWA. IF THE MORE PROGRESSIVE GFS SOLUTION VERIFIES...SNOW AMOUNTS WILL BE MUCH LIGHTER COMPARED TO THE SLOWER 00Z EC SOLUTION. WILL TAKE A CLOSE LOOK AT THE 12Z EC SOLUTION...AND IF IT IS PROGRESSIVE LIKE THE 12Z GFS...SOME ELIMINATION OF POPS ON MONDAY AND TUESDAY MAY BE IN ORDER. IN ADDITION TO ELIMINATING POPS MONDAY AND TUESDAY...IF THE MODEL COMES IN FASTER WITH THE SYSTEM...THE THREAT FOR LARGE ACCUMULATING SNOWS AND LONG DURATION PRECIPITATION WILL BE MINIMIZED. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 524 PM CST TUE MAR 5 2013 VFR IS EXPECTED ALL AREAS TONIGHT THROUGH 21Z WEDNESDAY. THEREAFTER...THERE ARE INDICATIONS IN THE MODELS THAT THE CLOUD DECK ACROSS THE MISSOURI BASIN WILL GET SWEPT WESTWARD AFFECTING AREAS EAST OF HIGHWAY 83. FLIGHT CONDITIONS COULD STILL REMAIN VFR AS CIGS WOULD OPERATE AT BKN035 BUT LOWER CIGS MIGHT DEVELOP. && .LBF WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...CDC SYNOPSIS...CLB SHORT TERM...MARTIN LONG TERM...CLB AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BUFFALO NY
355 AM EST WED MAR 6 2013 .SYNOPSIS... A SNOWSTORM WILL SLIDE SOUTHEAST ACROSS THE VIRGINIAS TODAY...WHILE JUST BRINGING SOME CLOUDS TO OUR AREA. AN UPPER LEVEL DISTURBANCE WILL THEN BRING A CHANCE FOR SOME LIGHT RAIN AND SNOW SHOWERS THURSDAY...WITH SOME STEADIER SNOW THEN EXPECTED FOR AREAS ALONG AND EAST OF THE GENESEE VALLEY THURSDAY NIGHT INTO EARLY FRIDAY. AFTER THAT...A RETURN TO DRY WEATHER AND INCREASING WARMTH WILL FOLLOW FOR THE WEEKEND WITH TEMPERATURES RISING ABOVE NORMAL. && .NEAR TERM /THROUGH TONIGHT/... IN THIS PERIOD...A COMPLEX WINTER STORM DRAPED FROM SOUTHERN OHIO TO NORTH CAROLINA WILL CONSOLIDATE INTO A SINGLE LOW ALONG THE VIRGINIA COASTLINE TODAY...BEFORE SLOWLY DRIFTING OFFSHORE TONIGHT IN RESPONSE TO A STRONG SHORTWAVE TROUGH DROPPING SOUTHEAST INTO THE GREAT LAKES. ON SUCH A TRACK...THIS SYSTEM/S SHIELD OF STEADY PRECIPITATION WILL REMAIN TO OUR SOUTH...WHILE OUR AREA REMAINS MAINLY DRY WITH JUST A GENERAL INCREASE IN CLOUD COVER EXPECTED OVER TIME. THE BEST CHANCES FOR ANY PRECIP MAY ACTUALLY COME LATER TONIGHT AS THE AFOREMENTIONED SHORTWAVE TROUGH APPROACHES FROM THE NORTHWEST...HOWEVER THE MOISTURE AND LIFT ASSOCIATED WITH THIS LOOKS WEAK ENOUGH TO KEEP POPS CONFINED TO THE SLIGHT CHANCE RANGE AND BELOW. WITH REGARD TO TEMPS...925 MB TEMPS SHOULD RECOVER BACK INTO THE -1C TO -3C RANGE TODAY AS WARMER AIR GETS DRAWN WESTWARD AROUND THE NORTH SIDE OF STORM SYSTEM. EVEN WITH AN INCREASE IN CLOUD COVER EXPECTED AND WINDS TURNING MORE NORTHEASTERLY OVER TIME...THIS SHOULD STILL BE ENOUGH FOR HIGHS TO REACH INTO THE MID TO UPPER 30S TODAY...WITH SOME SPOTS IN THE FINGER LAKES LIKELY REACHING 40 DEGREES. UNDER INCREASED AMOUNTS OF CLOUD COVER...LOWS TONIGHT WILL THEN RANGE FROM THE LOWER 20S ACROSS INTERIOR PORTIONS OF THE SOUTHERN TIER AND NORTH COUNTRY...TO THE UPPER 20S ACROSS THE LAKE PLAINS SOUTH OF LAKE ONTARIO. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... UNSETTLED WEATHER WILL RETURN TO WESTERN AND NORTH CENTRAL NEW YORK ON THURSDAY AS AN UPPER LEVEL LOW WILL DIVE SOUTHEAST ACROSS THE AREA FROM THE UPPER GREAT LAKES. LOOK FOR SCATTERED RAIN AND SNOW SHOWERS TO DEVELOP DURING THE DAY ON THURSDAY AND CHANGE OVER TO MAINLY SNOW SHOWERS DURING THE AFTERNOON AND EVENING AS THE COLD CORE OF THE LOW MOVES OVERHEAD. ACTIVITY ACROSS WESTERN NEW YORK SHOULD BE SCATTERED ENOUGH GIVEN THE POSITION DIRECTLY UNDERNEATH THE PASSING LOW AND TEMPERATURES SHOULD BE WARM ENOUGH THAT ANY SNOW ACCUMULATIONS SHOULD BE NEGLIGIBLE...ON THE ORDER OF A TENTH OR TWO ACROSS HIGHER ELEVATIONS OF THE SOUTHERN TIER WITH LITTLE IF ANY ACCUMULATIONS ELSEWHERE. EAST OF THE GENESEE VALLEY AND ACROSS THE NORTH COUNTRY THERE IS A POTENTIAL FOR MORE SIGNIFICANT SNOW ACCUMULATIONS. AS THE SHORTWAVE DIVES ACROSS WESTERN NEW YORK...THERE IS A POSSIBILITY THAT IT MAY INTERACT WITH AN INVERTED SURFACE TROUGH PROGGED TO EXTEND ACROSS THE HUDSON VALLEY AND UPSTATE NEW YORK FROM THE STORM SYSTEM CURRENTLY IMPACTING THE MID-ATLANTIC STATES TO PRODUCE SIGNIFICANT ACCUMULATIONS OF SNOW ACROSS PORTIONS OF UPSTATE NEW YORK INCLUDING THE COUNTIES EAST AND SOUTHEAST OF LAKE ONTARIO. HOWEVER AT THIS POINT THERE IS STILL A FAIR AMOUNT OF UNCERTAINTY AS TO HOW FAR NORTH/WEST THIS POTENTIAL BAND OF SNOW WILL DEVELOP AS THIS DEVELOPMENT WILL HINGE ON THE SPEED OF THE UPPER LEVEL TROUGH AND EXACTLY HOW FAR INLAND THE DEEPEST MOISTURE AND WARM ADVECTION WILL PENETRATE...WHICH IS ITSELF A FUNCTION OF THE EXACT TRACK OF THE DEVELOPING STORM SYSTEM AS IT DEPARTS THE EAST COAST. GIVEN ALL OF THE COMPLEX ISSUES...WILL HOLD OFF ON ANY WATCHES AT THIS POINT AND LOOK FOR GREATER CLARITY IN FUTURE MODEL RUNS. A ROBUST RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE LOWER GREAT LAKES ON FRIDAY IN THE WAKE OF THE DEPARTING LOW BRINGING A RETURN TO DRY WEATHER. NORTHERLY FLOW AHEAD OF THE HIGH WILL LIKELY KEEP A DECENT AMOUNT OF CLOUD COVER IN PLACE ACROSS THE AREA FOR MUCH OF THE DAY AND THIS MAY HOLD TEMPERATURES IN THE MID TO UPPER 30S...HOWEVER CLOUDS SHOULD GRADUALLY THIN OUT AS DRIER AIR WORKS ITS WAY ACROSS THE REGION LATER FRIDAY AFTERNOON AND EVENING. THE CLEARING SKIES AND DIMINISHING WINDS AS THE SURFACE HIGH MOVES OVERHEAD FRIDAY NIGHT WILL ALLOW TEMPERATURES TO DROP INTO THE 20S EVEN AS TEMPERATURES ALOFT RISE ABOVE NORMAL. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE RIDGE WILL SLIDE OFF TO THE EAST EARLY IN THE PERIOD AS BOTH THE GFS AND ECMWF SHOW A WEAK FRONTAL BOUNDARY CROSSING THE LOWER LAKES LATE IN THE WEEKEND. TIMING OF THE FRONTAL BOUNDARY IS HANDLED DIFFERENT BY THE TWO MODELS...AS THE MODELS HAVING DIFFICULTY HANDLING THE SHORT WAVE ENERGY COMING OUT OF THE PLAINS AND DAMPENING THE UPPER RIDGE. IT DOES APPEAR THAT MOISTURE WILL BE LIMITED ENOUGH TO KEEP PRECIPITATION IN THE BROADBRUSH LOW CHANCE CATEGORY...BUT THAT IS AS MUCH DETAIL AS CAN BE AFFORDED AT THIS POINT. USED A CONSENSUS OF GUIDANCE FOR THIS PERIOD GIVEN THE LIMITED CONFIDENCE IN ANY ONE MODEL. EVEN MORE UNCERTAINTY AND LOWER CONFIDENCE DEVELOPS EARLY NEXT WEEK AS MODELS STRUGGLE TO CONSISTENTLY HANDLE THE PHASING OF THE NORTHERN AND SOUTHERN STREAMS OVER THE CONUS. CONTINUED TO USE A CONSENSUS OF GUIDANCE...BUT OVERALL CONFIDENCE IN THIS PORTION OF THE FORECAST IS BELOW AVERAGE. THE OVERALL TEMPERATURE PATTERN SHOULD FEATURE A GENERAL WARMER THAN NORMAL REGIME. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... AS OF 08Z...SKIES REMAIN MAINLY CLEAR NORTH OF THE SOUTHERN TIER...WHILE SOME THICKER CIRRUS AND PATCHY STRATUS PERSIST FROM KJHW OVER TO KELZ. THROUGH SUNRISE...EXPECT A SUBSIDENCE INVERSION TO CONTINUE TO LOWER AND SHARPEN AND LIKELY LEAD TO SOME EXPANSION OF THE LOWER CLOUDS...HOWEVER THESE WILL REMAIN PATCHY IN COVERAGE AND MVFR IN NATURE GIVEN ONLY MARGINAL MOISTURE...WITH CONFIDENCE IN TIMING/LOCATION REMAINING LOW. BASED ON THE LATEST RAP AND THE 18Z NAM...WILL CARRY A PERIOD OF LLWS AT JHW. THROUGH THE REMAINDER OF TODAY AND TONIGHT...LOW PRESSURE WILL REMAIN WELL SOUTH AND EAST OF THE AREA. OVER TIME...INITIAL VFR/ PATCHY MVFR CONDITIONS THIS MORNING WILL GRADUALLY LOWER TO MVFR AS MOISTURE INCREASES IN THE LOWER LEVELS OF THE ATMOSPHERE...WITH SOME IFR CIGS BECOMING POSSIBLE ACROSS THE SOUTHERN TIER TONIGHT. OUTLOOK... THURSDAY...MVFR WITH A CHANCE OF RAIN AND SNOW SHOWERS. THURSDAY NIGHT...MVFR/IFR WITH LIGHT SNOW LIKELY FROM THE GENESEE VALLEY EASTWARD...OTHERWISE MVFR WITH A CHANCE OF SNOW SHOWERS FURTHER WEST. FRIDAY...MVFR WITH A CHANCE OF SNOW SHOWERS IN THE MORNING...THEN BECOMING MAINLY VFR. SATURDAY AND SUNDAY...VFR. && .MARINE... COMPLEX LOW PRESSURE DRAPED FROM SOUTHERN OHIO TO NORTH CAROLINA WILL CONSOLIDATE INTO A SINGLE LOW ALONG THE VIRGINIA COASTLINE TODAY...BEFORE SLOWLY DRIFTING OUT TO SEA TONIGHT AND THURSDAY. AS THIS SYSTEM PUSHES EASTWARD...THE BRISK EASTERLY FLOW CURRENTLY FOUND ACROSS THE LOWER LAKES WILL TURN MORE NORTHEASTERLY TODAY... THEN WILL GRADUALLY WEAKEN TONIGHT AND THURSDAY WHILE ALSO TENDING MORE NORTHERLY. THIS WILL EVENTUALLY LEAD TO WINDS AND WAVES FALLING BELOW ADVISORY CRITERIA OVER TIME...HOWEVER UNTIL THIS HAPPENS SMALL CRAFT ADVISORIES WILL REMAIN IN EFFECT AS OUTLINED BELOW. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EST THIS MORNING FOR LEZ040. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LOZ043. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 10 PM EST THIS EVENING FOR LOZ044. SMALL CRAFT ADVISORY UNTIL 10 PM EST THIS EVENING FOR LOZ042. && $$ SYNOPSIS...JJR NEAR TERM...JJR SHORT TERM...WOOD LONG TERM...TMA AVIATION...APFFEL/JJR MARINE...JJR
AREA FORECAST DISCUSSION
NWS RALEIGH NC
250 PM EST WED MAR 6 2013 .SYNOPSIS... A POWERFUL LOW PRESSURE SYSTEM OVER COASTAL VIRGINIA WILL MOVE OFFSHORE THROUGH TONIGHT. DRY HIGH PRESSURE WILL BUILD OVER THE EASTERN SEABOARD THURSDAY THROUGH THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY NIGHT/... AS OF 235 PM WEDNESDAY... THROUGH TONIGHT: IMPROVING WEATHER EXPECTED TONIGHT. LATEST SURFACE MAP SHOWS THE STRONG SURFACE LOW NEAR THE MOUTH OF CHESAPEAKE BAY. BANDS OF RAIN AND SNOW SHOWERS CONTINUE TO PIVOT AROUND THE LOW INTO NORTHEAST NC... ALTHOUGH THUS FAR THIS AFTERNOON -- IN CONTRAST TO THIS MORNING`S HRRR GUIDANCE -- THE SIGNIFICANT REFLECTIVITIES HAVE HELD LARGELY NORTH AND EAST OF OUR FORECAST AREA. EXTRAPOLATION OF EXISTING UPSTREAM PRECIP AND LOCAL WRF OUTPUT STILL SUPPORT PRECIP WORKING ACROSS THE NORTHEAST CWA... ALONG AND NE OF A LINE FROM OXFORD TO WILSON... FOR THE NEXT FEW HOURS. SURFACE WET BULBS ARE GENERALLY ABOVE FREEZING IN THIS AREA... SO EXPECT A PTYPE OF MOSTLY RAIN... ALTHOUGH HEAVIER BANDS MAY STILL MIX WITH A LITTLE INCONSEQUENTIAL WET SNOW IN THE FAR NORTHEAST. THE LOW SWINGS FARTHER OUT TO SEA THIS EVENING... LEAVING LITTLE MORE THAN PATCHY SPRINKLES BEFORE THE PRECIP THREAT ENDS ENTIRELY BY MIDNIGHT. REGARDING THE WINDS... WE`VE HAD NUMEROUS SITES ATTAIN PEAK GUSTS OF 40-46 MPH SO FAR TODAY WITH NEARLY ALL LOCATIONS SEEING 30 MPH GUSTS OR GREATER. THE DEPARTURE OF THE COASTAL LOW AND SUBSEQUENT SLOW SLACKENING OF THE MSLP GRADIENT AND GRADUAL DECREASE IN NEAR-SURFACE MIXING WILL RESULT IN SLOWLY DECREASING WINDS AS WE GO THROUGH THE EVENING. WILL LEAVE THE WIND ADVISORY IN PLACE UNTIL MIDNIGHT... ALTHOUGH IT MAY NEED TO BE CANCELED A FEW HOURS EARLY. EXPECT GRADUAL CLEARING SKIES FROM SW TO NORTHEAST AS WE DRY OUT IN THE LOWEST FEW THOUSAND FEET. DESPITE DEW POINTS IN THE 20S THROUGH TONIGHT... THE AIR SHOULD STAY JUST STIRRED ENOUGH NEAR THE GROUND TO KEEP LOWS UP A BIT... 29-34. FOR THURSDAY/THURSDAY NIGHT: WITH THE COLUMN DRYING OUT AND SINKING/ STABILIZING ALOFT... EXPECT QUITE A BIT OF SUNSHINE WITH PERHAPS SOME FLAT AFTERNOON CUMULUS. SURFACE HIGH PRESSURE CENTERED OVER ONTARIO AND THE UPPER MIDWEST/UPPER GREAT LAKES WILL EXTEND SOUTHWARD WITH RIDGING BUILDING SLOWLY INTO NC FROM THE NW. WINDS FROM THE NNW WILL NOT BE NEARLY AS STRONG AS THEY HAVE BEEN TODAY BUT THE MSLP GRADIENT REMAINS TIGHT ENOUGH TO TRANSLATE INTO SURFACE WINDS OF 10-15 KTS AND PERIODIC GUSTS TO 15-20 KTS BASED ON PROJECTED WINDS IN THE UPPER PORTIONS OF THE MIXED LAYER. LOW LEVEL THICKNESSES WILL BE AROUND 20-25 METERS BELOW NORMAL... SUGGESTING HIGHS OF 51-58... OR ROUGHLY TWO CATEGORIES BELOW NORMAL. THE MID LEVEL LOW NEAR LAKE SUPERIOR THIS MORNING WILL DROP TOWARD THE SOUTHEAST OVER PA/DEL LATE THURSDAY NIGHT... HOWEVER THE LACK OF MOISTURE AT ANY LEVEL AND NO OPPORTUNITY FOR AN MOISTURE TRANSPORT INTO NC WITH LOW LEVEL FLOW FROM THE NNW WILL ALLOW SKIES TO STAY GENERALLY CLEAR. LOWS 28-33 WITH 4-8 KTS OF WIND FROM THE NORTH. -GIH && .SHORT TERM /FRIDAY AND SUNDAY NIGHT/... AS OF 250 PM WEDNESDAY... AN OMEGA BLOCK WILL DEVELOP BY FRIDAY AS THE UPPER LOW OFF THE MID ATLANTIC COAST CONTINUES TO WOBBLE SLOWLY TOWARD THE NORTH ATLANTIC AND A CUTOFF LOW DEVELOPS OVER THE SOUTHWESTERN US. MEANWHILE...A DISTURBANCE CURRENTLY MOVING INTO THE UPPER GREAT LAKES AREA WILL BE DRAWN SOUTH ACROSS THE MID-ATLANTIC STATES AND CLIP NORTHEASTERN NC EARLY FRIDAY. DEEP MOISTURE IS FORECAST TO BE RATHER LIMITED...BUT ENHANCE CLOUD COVER OVER AT LEAST THE NORTHERN COASTAL PLAIN SEEMS FAIRLY LIKELY WITH THE GLANCING BLOW OF THE VORT MAX. FORECAST SOUNDINGS ALSO SHOW PERSISTENT BACKING OF THE LOW LEVEL FLOW...WITH 10-15KT SURFACE WIND...SUGGESTING ANOTHER SURGE OF COLD ADVECTION BEFORE HIGH PRESSURE BUILDS IN FROM THE GREAT LAKES FRIDAY NIGHT. THUS...WILL KEEP HIGHS A GOOD 4-6 DEGREES BELOW MOST GUIDANCE ON FRIDAY...49-55 NORTHEAST TO SOUTHWEST. LOWS FRIDAY NIGHT IN THE UPPER 20S TO LOWER 30S. RIDGING ALOFT WILL BUILD OVER HEAD SATURDAY THROUGH SUNDAY...WHILE SURFACE HIGH PRESSURE SETTLES ALONG THE EAST COAST. THIS WILL LEAD TO A MODERATING TREND IN TEMPS AS 850MB TEMPS APPROACH 10C AND LOW LEVEL THICKNESSES RISE ABOVE 1350M BY SUNDAY. HOWEVER...NORTHEASTERLY LOW LEVEL FLOW IS FORECAST TO CONTINUE SATURDAY...SO THE WARMING ALOFT MAY NOT BE COMPLETELY REALIZED FOR YET ANOTHER DAY. THE MORE NOTICEABLE WARMUP WILL BE FELT IN THE NORTHEAST CWA ON SATURDAY...WITH HIGHS RANGING FROM THE MID 50S NORTHEAST TO AROUND 60 SOUTHWEST. THE SURFACE HIGH IS FORECAST TO SHIFT OFFSHORE BY SUNDAY...AND IF THIS OCCURS...THEN WEAK RETURN FLOW WOULD DEVELOP AND HELP PUSH HIGHS INTO THE MID 60S. DRY CONDITIONS WILL PERSIST BENEATH THE RIDGE. && .LONG TERM /MONDAY THROUGH WEDNESDAY/... AS OF 250 PM WEDNESDAY... THE OMEGA BLOCK OVER THE CONUS IS FORECAST TO WEAKEN BY MONDAY..ALLOWING AN UPPER LOW OVER THE SOUTHWESTERN US TO EJECT EASTWARD ACROSS THE SOUTHERN PLAINS AND DEAMPLIFY AS IT LIFTS TOWARD THE MIDWEST STATES . SOUTHERLY RETURN FLOW AHEAD OF THE SYSTEM SHOULD PUSH TEMPS WELL ABOVE NORMAL MONDAY WITH LOW LEVEL THICKNESSES PROGGED TO APPROACH 1360M. BASED ON THIS...UPPER 60S SEEM LIKELY AND LOWER 70S POSSIBLE UNLESS CLOUD COVER IS MORE ROBUST THAN FORECAST. AS THE UPPER TROUGH AND PRIMARY SURFACE LOW LIFT ACROSS THE MIDWEST AND OH VALLEY...THE ATTENDANT COLD FRONT IS EXPECTED TO MOVE CROSS THE MOUNTAINS MONDAY NIGHT/TUESDAY. THE GFS AND ECMWF HAVE WAVERED BACK AND FORTH A BIT REGARDING THE EXACT TIMING OF THE FRONTAL PASSAGE AND SENSIBLE WEATHER...BUT THEIR SOLUTIONS ARE GENERALLY WITHIN 12 HOURS OF EACH OTHER. HOWEVER...THERE ARE STILL ENOUGH DIFFERENCES IN THE MASS FIELDS TO KEEP POPS BELOW 50 PERCENT AT THIS TIME. SHOULD ALSO NOTE THAT AS WE MOVE FURTHER INTO MARCH...THIS TYPE OF PATTERN WILL BRING A BETTER CHANCE OF THUNDERSTORMS ACCOMPANYING THE COLD FRONT...BUT WE WILL HOLD OFF ON INCLUDING THUNDER IN THE FORECAST UNTIL TIMING OF THE SYSTEM AND MOISTURE RETURN ARE MORE CERTAIN. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 1230 PM WEDNESDAY... VFR CONDITIONS ARE EXPECTED TO PERSIST AT INT/GSO/FAY WELL INTO WEDNESDAY. RDU/RWI WILL REMAIN CLOSER TO THE LOW CLOUD SHIELD (MVFR TO HIGH-END IFR CIGS) ASSOCIATED WITH THE STRONG STORM CENTERED OVER THE SE COAST OF VA... SO A PERIOD OF MVFR CIGS AND BRIEF MVFR VSBYS WITHIN LIGHT RAIN SHOWERS (POSSIBLY MIXED WITH WET SNOW) ARE POSSIBLE THIS AFTERNOON UNTIL 23Z-01Z. AS THIS STORM SYSTEM HEADS OFF THE COAST THIS EVENING... SKIES WILL CLEAR OUT SW TO NE. STRONG WINDS COMING FROM THE WEST AND NW WILL REMAIN AN AVIATION HAZARD THROUGH EARLY TO MID EVENING... PRESENTING A SIGNIFICANT CROSSWIND PRIMARILY AT GSO/RDU/RWI/FAY. SUSTAINED WINDS OF 15-25 KTS AND GUSTS TO 30-38 KTS ARE EXPECTED THROUGH 22Z... THEN NW WINDS WILL BE DIMINISHING THROUGH THE EVENING AS THEY BECOME NORTHERLY. UNLIMITED SKIES AND NORTH WINDS 7-12 KTS ARE EXPECTED AFTER SUNRISE THURSDAY. LOOKING BEYOND 18Z THURSDAY... VFR CONDITIONS WILL DOMINATE THROUGH EARLY FRIDAY. BRIEF MVFR CIGS ARE POSSIBLE FRIDAY AFTERNOON INTO FRIDAY NIGHT AS LOW PRESSURE MOVES BY TO OUR NORTHEAST. THEN AS A STORM SYSTEM APPROACHES FROM THE WEST... IFR CIGS ARE POSSIBLE EARLY MONDAY MORNING... LIFTING TO VFR BY MONDAY AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...SMITH LONG TERM...SMITH AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
235 PM EST WED MAR 6 2013 .SYNOPSIS... A POWERFUL LOW PRESSURE SYSTEM OVER COASTAL VIRGINIA WILL MOVE OFFSHORE THROUGH TONIGHT. DRY HIGH PRESSURE WILL BUILD OVER THE EASTERN SEABOARD THURSDAY THROUGH THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY NIGHT/... AS OF 235 PM WEDNESDAY... THROUGH TONIGHT: IMPROVING WEATHER EXPECTED TONIGHT. LATEST SURFACE MAP SHOWS THE STRONG SURFACE LOW NEAR THE MOUTH OF CHESAPEAKE BAY. BANDS OF RAIN AND SNOW SHOWERS CONTINUE TO PIVOT AROUND THE LOW INTO NORTHEAST NC... ALTHOUGH THUS FAR THIS AFTERNOON -- IN CONTRAST TO THIS MORNING`S HRRR GUIDANCE -- THE SIGNIFICANT REFLECTIVITIES HAVE HELD LARGELY NORTH AND EAST OF OUR FORECAST AREA. EXTRAPOLATION OF EXISTING UPSTREAM PRECIP AND LOCAL WRF OUTPUT STILL SUPPORT PRECIP WORKING ACROSS THE NORTHEAST CWA... ALONG AND NE OF A LINE FROM OXFORD TO WILSON... FOR THE NEXT FEW HOURS. SURFACE WET BULBS ARE GENERALLY ABOVE FREEZING IN THIS AREA... SO EXPECT A PTYPE OF MOSTLY RAIN... ALTHOUGH HEAVIER BANDS MAY STILL MIX WITH A LITTLE INCONSEQUENTIAL WET SNOW IN THE FAR NORTHEAST. THE LOW SWINGS FARTHER OUT TO SEA THIS EVENING... LEAVING LITTLE MORE THAN PATCHY SPRINKLES BEFORE THE PRECIP THREAT ENDS ENTIRELY BY MIDNIGHT. REGARDING THE WINDS... WE`VE HAD NUMEROUS SITES ATTAIN PEAK GUSTS OF 40-46 MPH SO FAR TODAY WITH NEARLY ALL LOCATIONS SEEING 30 MPH GUSTS OR GREATER. THE DEPARTURE OF THE COASTAL LOW AND SUBSEQUENT SLOW SLACKENING OF THE MSLP GRADIENT AND GRADUAL DECREASE IN NEAR-SURFACE MIXING WILL RESULT IN SLOWLY DECREASING WINDS AS WE GO THROUGH THE EVENING. WILL LEAVE THE WIND ADVISORY IN PLACE UNTIL MIDNIGHT... ALTHOUGH IT MAY NEED TO BE CANCELED A FEW HOURS EARLY. EXPECT GRADUAL CLEARING SKIES FROM SW TO NORTHEAST AS WE DRY OUT IN THE LOWEST FEW THOUSAND FEET. DESPITE DEW POINTS IN THE 20S THROUGH TONIGHT... THE AIR SHOULD STAY JUST STIRRED ENOUGH NEAR THE GROUND TO KEEP LOWS UP A BIT... 29-34. FOR THURSDAY/THURSDAY NIGHT: WITH THE COLUMN DRYING OUT AND SINKING/ STABILIZING ALOFT... EXPECT QUITE A BIT OF SUNSHINE WITH PERHAPS SOME FLAT AFTERNOON CUMULUS. SURFACE HIGH PRESSURE CENTERED OVER ONTARIO AND THE UPPER MIDWEST/UPPER GREAT LAKES WILL EXTEND SOUTHWARD WITH RIDGING BUILDING SLOWLY INTO NC FROM THE NW. WINDS FROM THE NNW WILL NOT BE NEARLY AS STRONG AS THEY HAVE BEEN TODAY BUT THE MSLP GRADIENT REMAINS TIGHT ENOUGH TO TRANSLATE INTO SURFACE WINDS OF 10-15 KTS AND PERIODIC GUSTS TO 15-20 KTS BASED ON PROJECTED WINDS IN THE UPPER PORTIONS OF THE MIXED LAYER. LOW LEVEL THICKNESSES WILL BE AROUND 20-25 METERS BELOW NORMAL... SUGGESTING HIGHS OF 51-58... OR ROUGHLY TWO CATEGORIES BELOW NORMAL. THE MID LEVEL LOW NEAR LAKE SUPERIOR THIS MORNING WILL DROP TOWARD THE SOUTHEAST OVER PA/DEL LATE THURSDAY NIGHT... HOWEVER THE LACK OF MOISTURE AT ANY LEVEL AND NO OPPORTUNITY FOR AN MOISTURE TRANSPORT INTO NC WITH LOW LEVEL FLOW FROM THE NNW WILL ALLOW SKIES TO STAY GENERALLY CLEAR. LOWS 28-33 WITH 4-8 KTS OF WIND FROM THE NORTH. -GIH && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 230 AM WEDNESDAY... FRIDAY AND FRIDAY NIGHT: VERTICALLY STACKED LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO HANG AROUND SEVERAL HUNDRED MILES OFF THE MID ATLANTIC COAST ON FRIDAY... BEFORE PICKING UP SOME EAST/EAST-SOUTHEASTWARD MOMENTUM ON FRIDAY NIGHT AS ADDITIONAL S/W ENERGY IN THE FORM OF A BIT WEAKER CLOSED LOW DIVES SOUTHEASTWARD FROM THE GREAT LAKES REGION THURSDAY NIGHT INTO FRIDAY (BEFORE BEING ABSORBED BY THE DEEP CYCLONIC VORTEX OFF THE MID ATLANTIC COAST LATE FRIDAY INTO FRIDAY NIGHT). THIS ADDITIONAL ENERGY HAS TRENDED A BIT FURTHER WESTWARD WITH ITS TRACK... YET STILL EXPECTED TO ONLY SIDE SWIPE OUR COASTAL PLAIN AND NORTHEASTERN PIEDMONT COUNTIES FRIDAY INTO FRIDAY EVENING. GIVEN THE OVERALL LACK OF MOISTURE EXPECTED ACROSS OUR AREA AND THE CURRENT TRACK OF THE DISTURBANCE EXPECT WE SHOULD REMAIN DRY... WITH ONLY A POSSIBLE INCREASE IN SOME CLOUD COVER ON FRIDAY AFTERNOON INTO THE EVENING ACROSS EASTERN PORTIONS OF CENTRAL NC. HOWEVER... THE CLOUD COVER COULD HAVE AN IMPACT ON HIGH TEMPERATURES FOR FRIDAY ACROSS EASTERN/NORTHEASTERN PORTIONS OF THE RAH CWA. PLAN TO GO ON THE COOLER SIDE OF GUIDANCE FOR MOST OF THE AREA AGAIN GIVEN THIS ALONG WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO RUN SOME 20 TO 30 METERS BELOW NORMAL FOR THIS TIME OF YEAR... PLUS A POSSIBLE SNOW PACK TO THE NORTH OF THE CWA WITH CONTINUED NORTH-NORTHWESTERLY LOW LEVEL FLOW. THIS YIELDS HIGH TEMPS FROM AROUND 50 NE TO THE UPPER 50S SW. IN ADDITION TO THE CHILLY TEMPS... EXPECT WE SHOULD CONTINUE TO HAVE WINDS IN THE 10 TO 15 MPH RANGE... WITH GUSTS AS HIGH AS 25 MPH. ANY CLOUD COVER ASSOCIATED WITH THE AFOREMENTIONED DISTURBANCE SHOULD BEGIN TO SHIFT TO THE EAST OF THE AREA... WITH SUBSIDENCE IN THE WAKE OF THE DISTURBANCE (NAM WOULD SUGGEST A BIT SLOWER TIMING BUT APPEARS TO BE A SLOW OUTLIER WRT THE TIMING OF THE DISTURBANCE). WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA AND CLEARING SKIES EXPECT WE WILL SEE TEMPS FALL INTO THE UPPER 20S TO LOWER 30S FOR LOWS SATURDAY MORNING... WITH A LIGHT NORTH-NORTHWESTERLY BREEZE OVERNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY... S/W RIDGING IS EXPECTED TO BUILD ACROSS THE REGION FOR THE WEEKEND... WHILE SURFACE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE. THIS WILL RESULT IN QUITE WEATHER ACROSS CENTRAL NC THIS WEEKEND... WITH A WARMING TREND. EXPECT HIGH TEMPS ON SATURDAY WILL BE IN THE MID TO UPPER 50S... WITH MAYBE A FEW LOCATIONS TOUCHING 60 ACROSS THE FAR SOUTH OR SOUTHWEST WITH MOSTLY SUNNY SKIES. HIGH SUNDAY ARE EXPECTED TO BE EVEN WARMER... AS AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO FINALLY BE SLIGHTLY ABOVE NORMAL. THUS... EXPECT HIGH TEMPS WILL WARM INTO THE LOWER TO MID 60S BY SUNDAY AFTERNOON WITH INCREASING HIGH LEVEL CLOUD COVER. LOWS SUNDAY MORNING ARE EXPECTED TO BE IN THE LOWER TO MID 30S... WITH EXCELLENT RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT AND VARIABLE TO CALM WINDS AS HIGH PRESSURE ALOFT AND THE SURFACE WILL SETTLE OVER THE AREA. THE NEXT SYSTEM IS EXPECTED TO MOVE INTO THE AREA EARLY NEXT WEEK AS A DEEP TROUGH AND ASSOCIATED COLD FRONT SHIFT EASTWARD AND EVENTUALLY ACROSS THE REGION. THE OPERATIONAL GFS AND ECMWF HAVE COME INTO MUCH BETTER AGREEMENT ON THE TIMING OF THE SYSTEM... AND NOW BOTH SHOW AT LEAST SOME PHASING/INTERACTION OF THIS SYSTEM (WHICH ORIGINATES FROM A CLOSED LOW IN THE SOUTHWESTERN U.S. LATE THIS WEEK) WITH A NORTHERN STREAM TROUGH. BOTH THE 00Z ECMWF AND 00Z GFS SHOW AN AREA OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS MOVING ACROSS THE AREA LATE MONDAY AFTERNOON INTO TUESDAY MORNING... ALONG WITH THE PASSAGE OF A STRONG COLD FRONT BY TUESDAY MORNING. WPC (FORMERLY KNOW AS HPC... NOW THE WEATHER PREDICTION CENTER) PREFERS A BIT SLOWER TIMING... LAGGING THE TIMING OF THE FRONT AND CONTINUED CHANCES FOR SHOWERS AND POSSIBLY STORMS INTO THE DAY TUESDAY... AS THEY PREFER THE EUROPEAN CENTRE ENSEMBLE MEAN AS THEY NOTED IT OUTSTANDING PERFORMANCE WITH THE SYNOPTIC FLOW OF LATE. THUS... WILL TREND THE TIMING A BIT SLOWER THAN THE CURRENT OPERATIONAL MODELS ADVERTISE... WITH A GOOD CHANCE OF RAIN STILL LATE MONDAY INTO TUESDAY MORNING. EXPECT HIGHS TO BE IN THE 60S TO POSSIBLY 70S EAST MONDAY... WITH UPPER 50S TO 60S TUESDAY (HIGHLY DEPENDENT ON THE TIMING OF THE FRONT). LOWS EARLY NEXT WEEK ARE EXPECTED TO BE IN THE 40S TO EVEN AROUND 50 ON TUESDAY MORNING (AGAIN TIED TO THE EVENTUAL TIMING OF THE FRONT). && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 1230 PM WEDNESDAY... VFR CONDITIONS ARE EXPECTED TO PERSIST AT INT/GSO/FAY WELL INTO WEDNESDAY. RDU/RWI WILL REMAIN CLOSER TO THE LOW CLOUD SHIELD (MVFR TO HIGH-END IFR CIGS) ASSOCIATED WITH THE STRONG STORM CENTERED OVER THE SE COAST OF VA... SO A PERIOD OF MVFR CIGS AND BRIEF MVFR VSBYS WITHIN LIGHT RAIN SHOWERS (POSSIBLY MIXED WITH WET SNOW) ARE POSSIBLE THIS AFTERNOON UNTIL 23Z-01Z. AS THIS STORM SYSTEM HEADS OFF THE COAST THIS EVENING... SKIES WILL CLEAR OUT SW TO NE. STRONG WINDS COMING FROM THE WEST AND NW WILL REMAIN AN AVIATION HAZARD THROUGH EARLY TO MID EVENING... PRESENTING A SIGNIFICANT CROSSWIND PRIMARILY AT GSO/RDU/RWI/FAY. SUSTAINED WINDS OF 15-25 KTS AND GUSTS TO 30-38 KTS ARE EXPECTED THROUGH 22Z... THEN NW WINDS WILL BE DIMINISHING THROUGH THE EVENING AS THEY BECOME NORTHERLY. UNLIMITED SKIES AND NORTH WINDS 7-12 KTS ARE EXPECTED AFTER SUNRISE THURSDAY. LOOKING BEYOND 18Z THURSDAY... VFR CONDITIONS WILL DOMINATE THROUGH EARLY FRIDAY. BRIEF MVFR CIGS ARE POSSIBLE FRIDAY AFTERNOON INTO FRIDAY NIGHT AS LOW PRESSURE MOVES BY TO OUR NORTHEAST. THEN AS A STORM SYSTEM APPROACHES FROM THE WEST... IFR CIGS ARE POSSIBLE EARLY MONDAY MORNING... LIFTING TO VFR BY MONDAY AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...BSD LONG TERM...BSD AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
1230 PM EST WED MAR 6 2013 .SYNOPSIS... A POWERFUL LOW PRESSURE SYSTEM OVER SOUTHEAST VIRGINIA WILL MOVE SLOWLY EAST OUT OVER THE ATLANTIC LATER TODAY THROUGH TONIGHT. DRY HIGH PRESSURE WILL SLOWLY BUILD OVER THE EASTERN SEABOARD THURSDAY THROUGH THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY NIGHT/... AS OF 955 AM WEDNESDAY... REST OF TODAY: STRONG GRADIENT WINDS AND THE CHANCE OF SNOW SHOWERS OVER NORTH CENTRAL SECTIONS REMAIN SIGNIFICANT FORECAST CONCERNS. LATEST SURFACE MAP SHOWS THE SURFACE LOW CENTER JUST NORTH OF WILLIAMSBURG VA. MOSTLY LIGHT SNOW SHOWERS... OCCASIONALLY CHANGING BACK TO RAIN WHEN RATES DECREASE... CONTINUE TO PIVOT OVER THE FAR NORTH CENTRAL AND NORTHEAST CWA. WE`VE RECEIVED A FEW REPORTS OF LIGHT ACCUMULATION ON GRASSY AREAS FROM A FEW SPOTS THIS MORNING... AND THIS SEEMS TO HAVE BEEN THE CASE BENEATH THE AREAS OF HEAVIER REFLECTIVITIES... ONE BAND OF WHICH IS PROGRESSING THROUGH FRANKLIN TOWARD NASH COUNTY. WE ARE STILL CANVASSING THE COUNTIES AND TOWNS THERE TO DETERMINE THE DEGREE OF IMPACT OF THE SNOW THAT HAS FALLEN SO FAR... BUT BASED ON THE RADAR TRENDS AND RECENT HRRR RUNS WHICH SUGGEST THAT SOME OF THE HEAVIER SNOW SHOWERS OVER SOUTH CENTRAL VA MAY TRACK SOUTH OF THE BORDER... A SHORT-TERM ADVISORY MAY BE NEEDED HERE. IN ANY CASE... BASED ON THE OBSERVED AND EXPECTED WET BULB TEMPS THAT SHOULD HOLD VERY CLOSE TO FREEZING OR JUST ABOVE... AND WITH FAIRLY MILD ROAD TEMPS... ROADS SHOULD BE JUST WET WITH ANY ACCUMULATION ON THE GRASSY AREAS ONLY. WILL CONTINUE TO MONITOR. THE WIND ADVISORY WILL REMAIN AS IS. SEVERAL GUSTS OVER 30 KTS HAVE ALREADY BEEN REPORTED... PRIMARILY IN LOCATIONS THAT HAVE SEEN SOME SUNSHINE THIS MORNING... IN THE FAR WEST AND ACROSS THE SOUTHERN CWA. OBSERVED 925 MB TEMPS FROM UPPER AIR SOUNDINGS ARE AROUND 30 KTS... AND AROUND 35-40 KT AT 850 MB... SO WITH GOOD MIXING EXPECT FREQUENT GUSTS TO AROUND 35-45 MPH. HIGHS FROM 36-40 NORTH TO AROUND 50 IN THE SOUTH. -GIH TONIGHT...SHOULD SEE PRECIP CHANCES END EARLY IN THE FAR NE AS THE LOW PRESSURE SYSTEM PULLS FARTHER AWAY. CLEARING SKIES WILL TREND EWD DURING THE NIGHT. DUE TOT HE LARGE WIND FIELD ASSOCIATED WITH THE SYSTEM...EXPECT WINDY/BREEZY CONDITIONS TO PERSIST THROUGH MOST OF THE NIGHT. THIS MIXING WILL PREVENT TEMPS FROM REACHING THEIR FULL COOLING POTENTIAL. MIN TEMPS INT HE 30-35 DEGREE RANGE. THURSDAY...WE WILL REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW THOUGH THE ASSOCIATED SUBSIDENCE ON THE BACK SIDE SHOULD MAINTAIN CLEAR SKIES OVER MOST OF THE REGION. NLY WINDS WILL GUSTS TO AROUND 25 KTS...ESPECIALLY IN THE MORNING...AND MAINLY EAST OF HIGHWAY 1. 850MB THERMAL TROUGH AND ASSOCIATED LOW LEVEL CAA WILL PERSIST THROUGH THU. THIS YIELDS LOW LEVEL THICKNESSES ABOUT 25M BELOW NORMAL. THIS WOULD SUGGEST MAX TEMPS ABOUT 6-9 DEGREES BELOW NORMAL. FAVOR MAX TEMPS ABOUT 4 DEGREES BELOW GUIDANCE...RANGING FROM NEAR 50 FAR NE TO THE MID 50S SOUTH. THURSDAY NIGHT...SURFACE HIGH PRESSURE WILL BEGIN TO INFLUENCE OUR SENSIBLE WEATHER. PRESSURE GRADIENT ANALYSIS SUGGEST SOME POTENTIAL FOR A LIGHT WIND THROUGH THE NIGHT. IF SFC WIND ABLE TO DECOUPLE...COULD SEE TEMPS FALL ABOUT 3-4 DEGREES COOLER THAN CURRENTLY FORECAST. FOR NOW...WILL MAINTAIN MIN TEMPS NEAR 30 TO LOWER 30S. -WSS && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 230 AM WEDNESDAY... FRIDAY AND FRIDAY NIGHT: VERTICALLY STACKED LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO HANG AROUND SEVERAL HUNDRED MILES OFF THE MID ATLANTIC COAST ON FRIDAY... BEFORE PICKING UP SOME EAST/EAST-SOUTHEASTWARD MOMENTUM ON FRIDAY NIGHT AS ADDITIONAL S/W ENERGY IN THE FORM OF A BIT WEAKER CLOSED LOW DIVES SOUTHEASTWARD FROM THE GREAT LAKES REGION THURSDAY NIGHT INTO FRIDAY (BEFORE BEING ABSORBED BY THE DEEP CYCLONIC VORTEX OFF THE MID ATLANTIC COAST LATE FRIDAY INTO FRIDAY NIGHT). THIS ADDITIONAL ENERGY HAS TRENDED A BIT FURTHER WESTWARD WITH ITS TRACK... YET STILL EXPECTED TO ONLY SIDE SWIPE OUR COASTAL PLAIN AND NORTHEASTERN PIEDMONT COUNTIES FRIDAY INTO FRIDAY EVENING. GIVEN THE OVERALL LACK OF MOISTURE EXPECTED ACROSS OUR AREA AND THE CURRENT TRACK OF THE DISTURBANCE EXPECT WE SHOULD REMAIN DRY... WITH ONLY A POSSIBLE INCREASE IN SOME CLOUD COVER ON FRIDAY AFTERNOON INTO THE EVENING ACROSS EASTERN PORTIONS OF CENTRAL NC. HOWEVER... THE CLOUD COVER COULD HAVE AN IMPACT ON HIGH TEMPERATURES FOR FRIDAY ACROSS EASTERN/NORTHEASTERN PORTIONS OF THE RAH CWA. PLAN TO GO ON THE COOLER SIDE OF GUIDANCE FOR MOST OF THE AREA AGAIN GIVEN THIS ALONG WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO RUN SOME 20 TO 30 METERS BELOW NORMAL FOR THIS TIME OF YEAR... PLUS A POSSIBLE SNOW PACK TO THE NORTH OF THE CWA WITH CONTINUED NORTH-NORTHWESTERLY LOW LEVEL FLOW. THIS YIELDS HIGH TEMPS FROM AROUND 50 NE TO THE UPPER 50S SW. IN ADDITION TO THE CHILLY TEMPS... EXPECT WE SHOULD CONTINUE TO HAVE WINDS IN THE 10 TO 15 MPH RANGE... WITH GUSTS AS HIGH AS 25 MPH. ANY CLOUD COVER ASSOCIATED WITH THE AFOREMENTIONED DISTURBANCE SHOULD BEGIN TO SHIFT TO THE EAST OF THE AREA... WITH SUBSIDENCE IN THE WAKE OF THE DISTURBANCE (NAM WOULD SUGGEST A BIT SLOWER TIMING BUT APPEARS TO BE A SLOW OUTLIER WRT THE TIMING OF THE DISTURBANCE). WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA AND CLEARING SKIES EXPECT WE WILL SEE TEMPS FALL INTO THE UPPER 20S TO LOWER 30S FOR LOWS SATURDAY MORNING... WITH A LIGHT NORTH-NORTHWESTERLY BREEZE OVERNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY... S/W RIDGING IS EXPECTED TO BUILD ACROSS THE REGION FOR THE WEEKEND... WHILE SURFACE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE. THIS WILL RESULT IN QUITE WEATHER ACROSS CENTRAL NC THIS WEEKEND... WITH A WARMING TREND. EXPECT HIGH TEMPS ON SATURDAY WILL BE IN THE MID TO UPPER 50S... WITH MAYBE A FEW LOCATIONS TOUCHING 60 ACROSS THE FAR SOUTH OR SOUTHWEST WITH MOSTLY SUNNY SKIES. HIGH SUNDAY ARE EXPECTED TO BE EVEN WARMER... AS AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO FINALLY BE SLIGHTLY ABOVE NORMAL. THUS... EXPECT HIGH TEMPS WILL WARM INTO THE LOWER TO MID 60S BY SUNDAY AFTERNOON WITH INCREASING HIGH LEVEL CLOUD COVER. LOWS SUNDAY MORNING ARE EXPECTED TO BE IN THE LOWER TO MID 30S... WITH EXCELLENT RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT AND VARIABLE TO CALM WINDS AS HIGH PRESSURE ALOFT AND THE SURFACE WILL SETTLE OVER THE AREA. THE NEXT SYSTEM IS EXPECTED TO MOVE INTO THE AREA EARLY NEXT WEEK AS A DEEP TROUGH AND ASSOCIATED COLD FRONT SHIFT EASTWARD AND EVENTUALLY ACROSS THE REGION. THE OPERATIONAL GFS AND ECMWF HAVE COME INTO MUCH BETTER AGREEMENT ON THE TIMING OF THE SYSTEM... AND NOW BOTH SHOW AT LEAST SOME PHASING/INTERACTION OF THIS SYSTEM (WHICH ORIGINATES FROM A CLOSED LOW IN THE SOUTHWESTERN U.S. LATE THIS WEEK) WITH A NORTHERN STREAM TROUGH. BOTH THE 00Z ECMWF AND 00Z GFS SHOW AN AREA OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS MOVING ACROSS THE AREA LATE MONDAY AFTERNOON INTO TUESDAY MORNING... ALONG WITH THE PASSAGE OF A STRONG COLD FRONT BY TUESDAY MORNING. WPC (FORMERLY KNOW AS HPC... NOW THE WEATHER PREDICTION CENTER) PREFERS A BIT SLOWER TIMING... LAGGING THE TIMING OF THE FRONT AND CONTINUED CHANCES FOR SHOWERS AND POSSIBLY STORMS INTO THE DAY TUESDAY... AS THEY PREFER THE EUROPEAN CENTRE ENSEMBLE MEAN AS THEY NOTED IT OUTSTANDING PERFORMANCE WITH THE SYNOPTIC FLOW OF LATE. THUS... WILL TREND THE TIMING A BIT SLOWER THAN THE CURRENT OPERATIONAL MODELS ADVERTISE... WITH A GOOD CHANCE OF RAIN STILL LATE MONDAY INTO TUESDAY MORNING. EXPECT HIGHS TO BE IN THE 60S TO POSSIBLY 70S EAST MONDAY... WITH UPPER 50S TO 60S TUESDAY (HIGHLY DEPENDENT ON THE TIMING OF THE FRONT). LOWS EARLY NEXT WEEK ARE EXPECTED TO BE IN THE 40S TO EVEN AROUND 50 ON TUESDAY MORNING (AGAIN TIED TO THE EVENTUAL TIMING OF THE FRONT). && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... AS OF 1230 PM WEDNESDAY... VFR CONDITIONS ARE EXPECTED TO PERSIST AT INT/GSO/FAY WELL INTO WEDNESDAY. RDU/RWI WILL REMAIN CLOSER TO THE LOW CLOUD SHIELD (MVFR TO HIGH-END IFR CIGS) ASSOCIATED WITH THE STRONG STORM CENTERED OVER THE SE COAST OF VA... SO A PERIOD OF MVFR CIGS AND BRIEF MVFR VSBYS WITHIN LIGHT RAIN SHOWERS (POSSIBLY MIXED WITH WET SNOW) ARE POSSIBLE THIS AFTERNOON UNTIL 23Z-01Z. AS THIS STORM SYSTEM HEADS OFF THE COAST THIS EVENING... SKIES WILL CLEAR OUT SW TO NE. STRONG WINDS COMING FROM THE WEST AND NW WILL REMAIN AN AVIATION HAZARD THROUGH EARLY TO MID EVENING... PRESENTING A SIGNIFICANT CROSSWIND PRIMARILY AT GSO/RDU/RWI/FAY. SUSTAINED WINDS OF 15-25 KTS AND GUSTS TO 30-38 KTS ARE EXPECTED THROUGH 22Z... THEN NW WINDS WILL BE DIMINISHING THROUGH THE EVENING AS THEY BECOME NORTHERLY. UNLIMITED SKIES AND NORTH WINDS 7-12 KTS ARE EXPECTED AFTER SUNRISE THURSDAY. LOOKING BEYOND 18Z THURSDAY... VFR CONDITIONS WILL DOMINATE THROUGH EARLY FRIDAY. BRIEF MVFR CIGS ARE POSSIBLE FRIDAY AFTERNOON INTO FRIDAY NIGHT AS LOW PRESSURE MOVES BY TO OUR NORTHEAST. THEN AS A STORM SYSTEM APPROACHES FROM THE WEST... IFR CIGS ARE POSSIBLE EARLY MONDAY MORNING... LIFTING TO VFR BY MONDAY AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...BSD LONG TERM...BSD AVIATION...HARTFIELD
AREA FORECAST DISCUSSION
NWS RALEIGH NC
955 AM EST WED MAR 6 2013 .SYNOPSIS... A POWERFUL LOW PRESSURE SYSTEM OVER SOUTHEAST VIRGINIA WILL MOVE SLOWLY EAST OUT OVER THE ATLANTIC LATER TODAY THROUGH TONIGHT. DRY HIGH PRESSURE WILL SLOWLY BUILD OVER THE EASTERN SEABOARD THURSDAY THROUGH THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY NIGHT/... AS OF 955 AM WEDNESDAY... REST OF TODAY: STRONG GRADIENT WINDS AND THE CHANCE OF SNOW SHOWERS OVER NORTH CENTRAL SECTIONS REMAIN SIGNIFICANT FORECAST CONCERNS. LATEST SURFACE MAP SHOWS THE SURFACE LOW CENTER JUST NORTH OF WILLIAMSBURG VA. MOSTLY LIGHT SNOW SHOWERS... OCCASIONALLY CHANGING BACK TO RAIN WHEN RATES DECREASE... CONTINUE TO PIVOT OVER THE FAR NORTH CENTRAL AND NORTHEAST CWA. WE`VE RECEIVED A FEW REPORTS OF LIGHT ACCUMULATION ON GRASSY AREAS FROM A FEW SPOTS THIS MORNING... AND THIS SEEMS TO HAVE BEEN THE CASE BENEATH THE AREAS OF HEAVIER REFLECTIVITIES... ONE BAND OF WHICH IS PROGRESSING THROUGH FRANKLIN TOWARD NASH COUNTY. WE ARE STILL CANVASSING THE COUNTIES AND TOWNS THERE TO DETERMINE THE DEGREE OF IMPACT OF THE SNOW THAT HAS FALLEN SO FAR... BUT BASED ON THE RADAR TRENDS AND RECENT HRRR RUNS WHICH SUGGEST THAT SOME OF THE HEAVIER SNOW SHOWERS OVER SOUTH CENTRAL VA MAY TRACK SOUTH OF THE BORDER... A SHORT-TERM ADVISORY MAY BE NEEDED HERE. IN ANY CASE... BASED ON THE OBSERVED AND EXPECTED WET BULB TEMPS THAT SHOULD HOLD VERY CLOSE TO FREEZING OR JUST ABOVE... AND WITH FAIRLY MILD ROAD TEMPS... ROADS SHOULD BE JUST WET WITH ANY ACCUMULATION ON THE GRASSY AREAS ONLY. WILL CONTINUE TO MONITOR. THE WIND ADVISORY WILL REMAIN AS IS. SEVERAL GUSTS OVER 30 KTS HAVE ALREADY BEEN REPORTED... PRIMARILY IN LOCATIONS THAT HAVE SEEN SOME SUNSHINE THIS MORNING... IN THE FAR WEST AND ACROSS THE SOUTHERN CWA. OBSERVED 925 MB TEMPS FROM UPPER AIR SOUNDINGS ARE AROUND 30 KTS... AND AROUND 35-40 KT AT 850 MB... SO WITH GOOD MIXING EXPECT FREQUENT GUSTS TO AROUND 35-45 MPH. HIGHS FROM 36-40 NORTH TO AROUND 50 IN THE SOUTH. -GIH TONIGHT...SHOULD SEE PRECIP CHANCES END EARLY IN THE FAR NE AS THE LOW PRESSURE SYSTEM PULLS FARTHER AWAY. CLEARING SKIES WILL TREND EWD DURING THE NIGHT. DUE TOT HE LARGE WIND FIELD ASSOCIATED WITH THE SYSTEM...EXPECT WINDY/BREEZY CONDITIONS TO PERSIST THROUGH MOST OF THE NIGHT. THIS MIXING WILL PREVENT TEMPS FROM REACHING THEIR FULL COOLING POTENTIAL. MIN TEMPS INT HE 30-35 DEGREE RANGE. THURSDAY...WE WILL REMAIN UNDER THE INFLUENCE OF THE UPPER LEVEL LOW THOUGH THE ASSOCIATED SUBSIDENCE ON THE BACK SIDE SHOULD MAINTAIN CLEAR SKIES OVER MOST OF THE REGION. NLY WINDS WILL GUSTS TO AROUND 25 KTS...ESPECIALLY IN THE MORNING...AND MAINLY EAST OF HIGHWAY 1. 850MB THERMAL TROUGH AND ASSOCIATED LOW LEVEL CAA WILL PERSIST THROUGH THU. THIS YIELDS LOW LEVEL THICKNESSES ABOUT 25M BELOW NORMAL. THIS WOULD SUGGEST MAX TEMPS ABOUT 6-9 DEGREES BELOW NORMAL. FAVOR MAX TEMPS ABOUT 4 DEGREES BELOW GUIDANCE...RANGING FROM NEAR 50 FAR NE TO THE MID 50S SOUTH. THURSDAY NIGHT...SURFACE HIGH PRESSURE WILL BEGIN TO INFLUENCE OUR SENSIBLE WEATHER. PRESSURE GRADIENT ANALYSIS SUGGEST SOME POTENTIAL FOR A LIGHT WIND THROUGH THE NIGHT. IF SFC WIND ABLE TO DECOUPLE...COULD SEE TEMPS FALL ABOUT 3-4 DEGREES COOLER THAN CURRENTLY FORECAST. FOR NOW...WILL MAINTAIN MIN TEMPS NEAR 30 TO LOWER 30S. -WSS && .SHORT TERM /FRIDAY AND FRIDAY NIGHT/... AS OF 230 AM WEDNESDAY... FRIDAY AND FRIDAY NIGHT: VERTICALLY STACKED LOW PRESSURE SYSTEM IS EXPECTED TO CONTINUE TO HANG AROUND SEVERAL HUNDRED MILES OFF THE MID ATLANTIC COAST ON FRIDAY... BEFORE PICKING UP SOME EAST/EAST-SOUTHEASTWARD MOMENTUM ON FRIDAY NIGHT AS ADDITIONAL S/W ENERGY IN THE FORM OF A BIT WEAKER CLOSED LOW DIVES SOUTHEASTWARD FROM THE GREAT LAKES REGION THURSDAY NIGHT INTO FRIDAY (BEFORE BEING ABSORBED BY THE DEEP CYCLONIC VORTEX OFF THE MID ATLANTIC COAST LATE FRIDAY INTO FRIDAY NIGHT). THIS ADDITIONAL ENERGY HAS TRENDED A BIT FURTHER WESTWARD WITH ITS TRACK... YET STILL EXPECTED TO ONLY SIDE SWIPE OUR COASTAL PLAIN AND NORTHEASTERN PIEDMONT COUNTIES FRIDAY INTO FRIDAY EVENING. GIVEN THE OVERALL LACK OF MOISTURE EXPECTED ACROSS OUR AREA AND THE CURRENT TRACK OF THE DISTURBANCE EXPECT WE SHOULD REMAIN DRY... WITH ONLY A POSSIBLE INCREASE IN SOME CLOUD COVER ON FRIDAY AFTERNOON INTO THE EVENING ACROSS EASTERN PORTIONS OF CENTRAL NC. HOWEVER... THE CLOUD COVER COULD HAVE AN IMPACT ON HIGH TEMPERATURES FOR FRIDAY ACROSS EASTERN/NORTHEASTERN PORTIONS OF THE RAH CWA. PLAN TO GO ON THE COOLER SIDE OF GUIDANCE FOR MOST OF THE AREA AGAIN GIVEN THIS ALONG WITH AFTERNOON LOW LEVEL THICKNESS VALUES EXPECTED TO RUN SOME 20 TO 30 METERS BELOW NORMAL FOR THIS TIME OF YEAR... PLUS A POSSIBLE SNOW PACK TO THE NORTH OF THE CWA WITH CONTINUED NORTH-NORTHWESTERLY LOW LEVEL FLOW. THIS YIELDS HIGH TEMPS FROM AROUND 50 NE TO THE UPPER 50S SW. IN ADDITION TO THE CHILLY TEMPS... EXPECT WE SHOULD CONTINUE TO HAVE WINDS IN THE 10 TO 15 MPH RANGE... WITH GUSTS AS HIGH AS 25 MPH. ANY CLOUD COVER ASSOCIATED WITH THE AFOREMENTIONED DISTURBANCE SHOULD BEGIN TO SHIFT TO THE EAST OF THE AREA... WITH SUBSIDENCE IN THE WAKE OF THE DISTURBANCE (NAM WOULD SUGGEST A BIT SLOWER TIMING BUT APPEARS TO BE A SLOW OUTLIER WRT THE TIMING OF THE DISTURBANCE). WITH SURFACE HIGH PRESSURE BUILDING INTO THE AREA AND CLEARING SKIES EXPECT WE WILL SEE TEMPS FALL INTO THE UPPER 20S TO LOWER 30S FOR LOWS SATURDAY MORNING... WITH A LIGHT NORTH-NORTHWESTERLY BREEZE OVERNIGHT. && .LONG TERM /SATURDAY THROUGH TUESDAY/... AS OF 3 AM WEDNESDAY... S/W RIDGING IS EXPECTED TO BUILD ACROSS THE REGION FOR THE WEEKEND... WHILE SURFACE HIGH PRESSURE MOVES ACROSS THE AREA AND OFFSHORE. THIS WILL RESULT IN QUITE WEATHER ACROSS CENTRAL NC THIS WEEKEND... WITH A WARMING TREND. EXPECT HIGH TEMPS ON SATURDAY WILL BE IN THE MID TO UPPER 50S... WITH MAYBE A FEW LOCATIONS TOUCHING 60 ACROSS THE FAR SOUTH OR SOUTHWEST WITH MOSTLY SUNNY SKIES. HIGH SUNDAY ARE EXPECTED TO BE EVEN WARMER... AS AFTERNOON LOW LEVEL THICKNESS VALUES ARE EXPECTED TO FINALLY BE SLIGHTLY ABOVE NORMAL. THUS... EXPECT HIGH TEMPS WILL WARM INTO THE LOWER TO MID 60S BY SUNDAY AFTERNOON WITH INCREASING HIGH LEVEL CLOUD COVER. LOWS SUNDAY MORNING ARE EXPECTED TO BE IN THE LOWER TO MID 30S... WITH EXCELLENT RADIATIONAL COOLING CONDITIONS WITH MOSTLY CLEAR SKIES AND LIGHT AND VARIABLE TO CALM WINDS AS HIGH PRESSURE ALOFT AND THE SURFACE WILL SETTLE OVER THE AREA. THE NEXT SYSTEM IS EXPECTED TO MOVE INTO THE AREA EARLY NEXT WEEK AS A DEEP TROUGH AND ASSOCIATED COLD FRONT SHIFT EASTWARD AND EVENTUALLY ACROSS THE REGION. THE OPERATIONAL GFS AND ECMWF HAVE COME INTO MUCH BETTER AGREEMENT ON THE TIMING OF THE SYSTEM... AND NOW BOTH SHOW AT LEAST SOME PHASING/INTERACTION OF THIS SYSTEM (WHICH ORIGINATES FROM A CLOSED LOW IN THE SOUTHWESTERN U.S. LATE THIS WEEK) WITH A NORTHERN STREAM TROUGH. BOTH THE 00Z ECMWF AND 00Z GFS SHOW AN AREA OF SHOWERS AND POSSIBLY SOME THUNDERSTORMS MOVING ACROSS THE AREA LATE MONDAY AFTERNOON INTO TUESDAY MORNING... ALONG WITH THE PASSAGE OF A STRONG COLD FRONT BY TUESDAY MORNING. WPC (FORMERLY KNOW AS HPC... NOW THE WEATHER PREDICTION CENTER) PREFERS A BIT SLOWER TIMING... LAGGING THE TIMING OF THE FRONT AND CONTINUED CHANCES FOR SHOWERS AND POSSIBLY STORMS INTO THE DAY TUESDAY... AS THEY PREFER THE EUROPEAN CENTRE ENSEMBLE MEAN AS THEY NOTED IT OUTSTANDING PERFORMANCE WITH THE SYNOPTIC FLOW OF LATE. THUS... WILL TREND THE TIMING A BIT SLOWER THAN THE CURRENT OPERATIONAL MODELS ADVERTISE... WITH A GOOD CHANCE OF RAIN STILL LATE MONDAY INTO TUESDAY MORNING. EXPECT HIGHS TO BE IN THE 60S TO POSSIBLY 70S EAST MONDAY... WITH UPPER 50S TO 60S TUESDAY (HIGHLY DEPENDENT ON THE TIMING OF THE FRONT). LOWS EARLY NEXT WEEK ARE EXPECTED TO BE IN THE 40S TO EVEN AROUND 50 ON TUESDAY MORNING (AGAIN TIED TO THE EVENTUAL TIMING OF THE FRONT). && .AVIATION /12Z WEDNESDAY THROUGH SUNDAY/... AS OF 655 AM WEDNESDAY... CEILINGS HAVE IMPROVED ACROSS MUCH OF CENTRAL NC SINCE 3 AM WITH MOST LOCALES IN THE WEST INCLUDING KINT AND KGSO REPORTING VFR CEILINGS. ACROSS THE EAST...CEILINGS STILL MVFR BUT SHOULD GRADUALLY LIFT TO HIGH END MVFR/LOW END VFR BY 15-18Z. SCATTERED RAIN AND/OR SNOW SHOWERS WILL ROTATE EWD ACROSS THE REGION THIS MORNING...AND MAINLY ACROSS THE NE PIEDMONT AND NORTHERN COASTAL PLAIN THIS AFTERNOON. VERY WINDY CONDITIONS WILL OCCUR SHORTLY AS A DEEP LOW PRESSURE SYSTEM MOVES EWD AND TAKES A POSITION JUST OFF THE VA-NC COAST. SFC WINDS WILL VEER TO A MORE NW DIRECTION WITH SUSTAINED WINDS NEAR 20KTS AND FREQUENT GUSTS AROUND 40KTS. A SPORADIC GUST NEAR 50KTS CANNOT BE RULED OUT. THESE WINDS MAY CAUSE CROSSWIND ISSUES AT SEVERAL TERMINALS TODAY. THE STRONG UPPER LEVEL LOW WILL SLOWLY TRAVERSE EWD TONIGHT THROUGH THU. SUBSIDENCE BEHIND THE DEPARTING LOW WILL AID TO DIMINISH/DISSIPATE THE CLOUD COVER WEST-TO-EAST. WHILE CLOUDS WILL DEPART LATER TONIGHT...WINDY CONDITIONS WILL LINGER WELL INTO TONIGHT WITH BREEZY CONDITIONS LIKELY ON THURSDAY. THE BREEZY CONDITIONS SHOULD ABATE BY THU NIGHT AS HIGH PRESSURE BEGINS TO EXERT ITS INFLUENCE. VFR CONDITIONS EXPECTED ACROSS THE REGION LATER TONIGHT AND PERSISTING INTO SUNDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR NCZ007>011-021>028-038>043-073>078-083>086-088-089. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD/WSS SHORT TERM...BSD LONG TERM...BSD AVIATION...WSS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1239 AM EST WED MAR 6 2013 .SYNOPSIS... A POTENT STORM SYSTEM WILL CROSS THE AREA TONIGHT...BRINGING SHOWERS AND PERHAPS A RUMBLE OF THUNDER. COLDER AIR RETURNS ALONG WITH STRONG GUSTY WINDS WEDNESDAY INTO THURSDAY AS THIS STORM SYSTEM LIFTS OFF TO THE NORTHEAST. THE LATE WEEK PERIOD WILL FEATURE A RETURN OF SEASONABLE TEMPERATURES. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... AS OF 12:30 AM WEDNESDAY...SHOWERS HAVE ENDED FOR THE NIGHT AS RAIN-SHIELD MOVES OFFSHORE. HAVE UPDATED FORECAST ACCORDINGLY. COLD FRONT WILL BE MOVING OFFSHORE SHORTLY. NO OTHER CHANGES TO THE FORECAST WITH THE LATEST UPDATE. WIND ADVISORY REMAINS IN EFFECT. PREVIOUS DISCUSSION FOLLOWS: A POWERFUL UPPER LEVEL LOW IS STILL STRENGTHENING AS IT MOVES EAST ACROSS SOUTHERN KENTUCKY THIS EVENING AND TOWARD NORTHERN NORTH CAROLINA WEDNESDAY MORNING. SURFACE LOW PRESSURE CENTERED OVER SOUTHERN OHIO IS OCCLUDING AS A NEW CENTER DEVELOPING OVER THE NC WESTERN PIEDMONT BECOMES THE DOMINANT LOW. A COLD FRONT SOUTH OF THIS DEVELOPING LOW EXTENDS FROM NEAR MONROE NC SOUTH THROUGH COLUMBIA AND INTO EASTERN GEORGIA. SHOWERS AND EMBEDDED THUNDERSTORMS HAVE ACCOMPANIED THE COLD FRONT ACROSS GEORGIA AND INTO THE CAROLINAS THIS EVENING. THERMODYNAMIC CONDITIONS WERE MUCH MORE FAVORABLE FOR UPRIGHT CONVECTION ACROSS GEORGIA AND THE WESTERN HALF OF SOUTH CAROLINA EARLIER. AS THE LINE HAS MOVED INTO THE EASTERN CAROLINAS SURFACE CAPE IS ZERO...WHILE PARCELS LIFTED FROM 875 MB CONTAIN MEAGER INSTABILITY ESTIMATED BY THE LATEST RUC AT 100 J/KG OR LESS. BULK SHEAR THROUGH THE 0-6 KM LAYER IS EXTREME (60-70 KT) WHICH IS PROBABLY TOO MUCH GIVEN THE MEAGER INSTABILITY...RESULTING IN ANY UPDRAFTS GETTING DILUTED BY THE ENVIRONMENT. WHILE I AM MAINTAINING HIGH POPS FOR MEASURABLE PRECIP THIS EVENING...ACTUAL GAUGE-MEASURED RAINFALL AMOUNTS SHOULD REMAIN QUITE LOW: 0.05 TO 0.15 INCHES FOR MOST AREAS. AFTER THE FRONT SWEEPS OFFSHORE SHORTLY AFTER MIDNIGHT MUCH COLDER AIR WILL SURGE INTO THE AREA. THE CHANGE IN AIRMASS IS VERY SUDDEN: 850 MB TEMPS SHOULD FALL FROM +7C AT 00Z TO -5C AT 12Z... ACCOMPANIED BY SIMILAR EXTREME CHANGES IN LAYER THICKNESS VALUES AND MID-LEVEL HEIGHTS. AS THE UPPER LOW MAKES ITS CLOSEST APPROACH TO THE AREA WEDNESDAY AFTERNOON THE TROPOPAUSE SHOULD ACTUALLY LOWER TO JUST ABOVE 500 MB OR ABOUT 19000 FT AGL. THIS IS WELL BELOW TYPICAL VALUES AND SHOWS JUST HOW POWERFUL THIS SYSTEM IS. FORECAST SOUNDINGS FROM THE RUC...NAM AND GFS SHOW DRY ADIABATIC LAPSE RATES DEVELOPING THROUGH THE LOWEST SEVERAL THOUSAND FEET OF THE ATMOSPHERE BY 09Z (4 AM WEDNESDAY) AS COLD ADVECTION STRENGTHENS. WIND SPEEDS JUST 1000 FT AGL SHOULD INCREASE TO 30 KNOTS...AND TO NEARLY 40 KNOTS AT 2000 FT AGL. THIS MOMENTUM WILL WORK ITS WAY DOWN IN GUSTS LATE TONIGHT AND ESPECIALLY WEDNESDAY AFTER THE SUN RISES AND LAPSE RATES ARE FORCED TO BECOME DRY ADIABATIC OVER AN EVEN DEEPER LAYER. THE WIND ADVISORY RAISED EARLIER TODAY APPEARS TO BE AN EXCELLENT CALL! LOW TEMPERATURES TONIGHT SHOULD FALL TO AROUND 40 INLAND WITH MID 40S AT THE COAST...ALL WITH A DEEPLY MIXED ATMOSPHERE PREVENTING ANY HINT OF A RADIATIONAL INVERSION. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... AS OF 3 PM TUESDAY...STRONG LOW PRESSURE SYSTEM OVER THE MID ATLANTIC COAST EARLY WED MORNING WILL BE MOVE SLOWLY OFF THE COAST THROUGH THE PERIOD AS STRONG HIGH PRESSURE BUILDS IN BEHIND IT. A VERY TIGHT GRADIENT WILL EXIST BETWEEN THE TWO SYSTEMS THROUGH WED INTO THURS WITH DEEP LAYER W-NW WINDS ADVECTING IN VERY DRY AND COOL AIR ON BACK END OF LOW. EXPECT STRONG AND GUSTY WESTERLY WINDS INITIALLY ON WED BECOMING NORTHWEST ON THURS. WINDS WILL BE STRONGEST OVER COASTAL NORTH CAROLINA WHERE WINDS WILL RUN BETWEEN 20 TO 30 MPH WITH GUSTS UP TO 45 MPH. WILL ISSUE WIND ADVISORY FOR WEDNESDAY. COLD AND DRY ADVECTION WILL CONTINUE THROUGH WED INTO THURS ON THE BACK END OF THE LOW. PCP WATER VALUES DROP DOWN TO LESS THAN A QUARTER OF AN INCH AS DRY SLOT WRAPPING AROUND LOW MOVES INTO AREA. A POTENT VORT MAX ROTATES AROUND THE LOW THROUGH WED AFTN INTO EARLY EVENING OVER THE CAROLINAS. THIS WILL PRODUCE THE POTENTIAL FOR CLOUDS BUT FOR NOW WILL KEEP PCP OUT OF FORECAST WITH WESTERLY DOWNSLOPE FLOW THROUGH WED AFTN. POTENTIAL INCREASES THROUGH WED AFTERNOON. MODELS SHOW PCP WATER VALUES REACHING UP TO A HALF INCH REACHING INTO NORTHERN TIER COUNTIES OF CWA...BUT FOR THE MOST PART THE BEST CHC OF ANY PCP WILL BE NORTH OF AREA. TEMPS WILL BE SOMEWHAT CHALLENGING AS OVERNIGHT LOWS HEADING INTO WED WILL BE ON THE WARM SIDE...UP AROUND 50 AT DAYBREAK. BUT THEN PLENTY OF COOL AIR WILL RUSH IN FIRST FEW HOURS OF DAYBREAK. EXPECT HIGHEST TEMP FOR WED TO OCCUR JUST AROUND MIDNIGHT AND AFTERNOON TEMPS TO BE CLOSER TO 50. 850 TEMPS BOTTOM OUT RIGHT AROUND NOON ON WED WITH -5C. TEMPS WILL DROP INTO THE 30S IN CAA THROUGH WED NIGHT AND THEREFORE EXPECT TEMPS ON THE COOL SIDE AGAIN FOR THURS. WILL UNDERCUT GUIDANCE AND KEEP WITH LOWER 50S MOST PLACES ON THURS. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 300 PM TUESDAY...QUIET WEATHER FOR MUCH OF THE EXTENDED WITH TEMPS WARMING TO...POTENTIALLY...WELL ABOVE NORMAL EARLY NEXT WEEK. A COLD FRONT WILL APPROACH AT THE END OF THE PERIOD...BRINGING THE ONLY CHANCE FOR PRECIP. LARGE LOW PRESSURE OFF THE NEW ENGLAND COAST AND A RIDGE OF HIGH PRESSURE BUILDING DOWN FROM THE NW WILL KEEP COOL NORTHERLY FLOW ACROSS THE CAROLINAS FRIDAY. THE LOW PRESSURE WILL PUSH OFF TO THE EAST BY SATURDAY AS HIGH PRESSURE RIDGES DOWN TO THE GULF COAST THROUGH THE WKND...BECOMING CENTERED OVERHEAD SUNDAY. ALTHOUGH THIS KEEPS LIGHT NORTH WINDS AND WEAK CAA...TEMPS WILL GRADUALLY WARM FROM MID/UPPER 50S FRIDAY...INTO THE MID 60S SUNDAY THANKS TO THE LIGHTER WINDS AND FULL MARCH INSOLATION. AS HIGH PUSHES OFFSHORE MON/TUE...RETURN FLOW PUMPS MUCH WARMER AIR INTO THE REGION WITH TEMPS RISING TO WELL ABOVE NORMAL...APPROACHING 70 BOTH DAYS...ALTHOUGH HIGH LEVEL CLOUD COVER WILL BE ON THE INCREASE NEXT WEEK. MINS THROUGH THE PERIOD WILL GRADUALLY INCREASE AS WELL...FROM MID 30S FRIDAY NIGHT...TO UPPER 40S MON NIGHT. GUIDANCE SUGGESTS A COLD FRONT WILL CROSS EARLY TUESDAY...BUT EXPECT THIS TO BE SLOWED BY THE ANTECEDENT RIDGING AND INCREASINGLY BOUNDARY-PARALLEL MID LEVEL FLOW. DECENT THETA-E RIDGING AHEAD OF THIS FEATURE WILL SUPPORT SHOWERS TUESDAY...BUT BEING D7 AND EXPECTED SLOWING OF BOUNDARY WILL CARRY ONLY SCHC/SILENT FOR NOW ON TUE. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... AS OF 06Z...FRONT PROBABLY THROUGH FLO AND LBT AND WILL PUSH OFFSHORE SHORTLY AFTER TAF ISSUANCE. WINDS WILL SHIFT WESTERLY WITH MODERATE TO STRONG COLD AIR ADVECTION COMMENCING TOWARD MORNING. STRONG MIXING AND GRADIENT WILL KICK WINDS WELL INTO THE 30 KT RANGE BY MIDDAY. MOISTURE ROTATION AROUND THE STRONG LOW NORTH OF HERE...ALONG WITH COLD AIR ALOFT...WILL CREATE A STRATA CU CEILING MAINLY NORTH OF THE REGION...BUT LBT AND ILM MAY GET INTO THE ACT. LOOK FOR WINDS TO DIMINISH AFTER SUNSET...SETTLING DOWN THE MOST AT THE SOUTHERN TERMINALS WHERE THE GRADIENT IS RELATIVELY WEAKER. EXTENDED OUTLOOK...VFR CONDITIONS SHOULD PREVAIL THROUGH SUNDAY. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 12:30 AM WEDNESDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE MARINE FORECAST THIS EVENING. GALE WARNING REMAINS IN EFFECT FOR DANGEROUSLY STRONG WINDS AND HIGH SEAS ASSOCIATED WITH A STRONG FRONTAL SYSTEM THAT WILL SOON MOVE OFFSHORE. PREVIOUS DISCUSSION FOLLOWS: SOUTHWEST WINDS ARE STEADILY INCREASING AHEAD OF A STRONG COLD FRONT NOW PUSHING INTO THE WESTERN CAROLINAS. THIS FRONT WILL RAPIDLY MOVE EAST AND ACROSS THE COASTAL WATERS AFTER MIDNIGHT...ACCOMPANIED BY A LINE OF SHOWERS AND ISOLATED THUNDERSTORMS. BEHIND THE FRONT SURFACE PRESSURES WILL RISE RAPIDLY WHICH SHOULD RESULT IN THE ONSET OF GALE-FORCE WINDS...AT LEAST IN GUSTS...SEVERAL HOURS BEFORE SUNRISE. MODELS ARE IN EXCELLENT AGREEMENT WITH THE TIMING AND ANTICIPATED HIGH IMPACT OF THIS SYSTEM TO MARINERS. NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST WITH THIS EARLY EVENING UPDATE. SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... AS OF 3 PM TUESDAY...POTENT LOW PRESSURE SYSTEM WILL BE MOVING SLOWLY OFF THE MID ATLANTIC COAST THROUGH PERIOD. A VERY TIGHT GRADIENT WILL EXIST BETWEEN THIS LOW AND STRONG HIGH PRESSURE BUILDING IN ON THE BACK END. TIGHTENED GRADIENT FLOW COMBINED WITH COLD SURGE ON BACK END OF LOW WILL PRODUCE STRONG GUSTY WESTERLY WINDS UP TO 35 KTS WITH HIGHER GUSTS THROUGH WED. A GALE WARNING WILL REMAIN IN EFFECT INTO WED EVENING. MAX SEAS WILL BE WED MORNING UP AROUND 7 TO 10 FT WITH HIGHER SEAS JUST OUTSIDE OF LOCAL WATERS. THE OFF SHORE FLOW WILL ALLOW NEAR SHORE SEAS TO SUBSIDE BY THE END OF WED BUT STILL EXPECT 6 TO 8 FT SEAS THROUGH WED EVENING. EXPECT A SLOW DECREASE IN SPEEDS HEADING INTO THURSDAY AS THE LOW PRESSURE SYSTEM MOVES FURTHER OFF THE MID ATLANTIC COAST. SEAS WILL CONTINUE TO SUBSIDE IN SLOWLY WEAKENING OFF SHORE FLOW. EXPECT SEAS DOWN BELOW SCA BY DAYBREAK THURSDAY WITH HEIGHTS AROUND 4 TO 5 FT IN OUTER WATERS AND LESS THAN 3 FT NEAR SHORE. BY THURSDAY EVENING EXPECT SEAS 2-4 FEET ACROSS THE WATERS. LONG TERM /FRIDAY THROUGH SUNDAY/... AS OF 300 PM TUESDAY...VERY LARGE LOW PRESSURE MOVING SLOWLY OFF THE NEW ENGLAND COAST WILL KEEP A PINCHED GRADIENT WITH WINDS VEERING FROM NW TO NORTH THROUGH FRIDAY. WINDS WILL BE 15-20 KTS...WITH GUSTS UP TO 30 KTS DURING THE DAY. ALTHOUGH THIS IS PRIMARILY AN OFFSHORE DIRECTION...SEAS WILL REMAIN ELEVATED AT 2-5 FT. HOWEVER...AS WINDS BECOME SLIGHTLY MORE NORTHERLY LATE FRIDAY...WAVE HEIGHTS NEAR THE 20NM BOUNDARY OF AMZ250 AND AMZ252 MAY APPROACH 6FT...AND A SHORT SMALL CRAFT ADVISORY MAY BE NEEDED FRIDAY NIGHT THROUGH SATURDAY MORNING. SEAS THROUGH SATURDAY WILL BE FORMED VIA A COMBINATION OF NORTHERLY WIND WAVES...AND AN EASTERLY BACK SWELL OF 2-4 FT AT 13 SEC. HIGH PRESSURE BUILDS DOWN ACROSS THE AREA FROM THE NW SAT/SUN CAUSING WINDS TO SHIFT SLOWLY FROM NORTH TO SE BY LATE SUNDAY...WITH SPEEDS DECREASING TO LESS THAN 10 KTS DUE TO THE RELAXED GRADIENT. SEAS RESPOND ONLY SLOWLY WITH A 2-4 FT EASTERLY BACKSWELL PERSISTING WITHIN THE SPECTRUM. STILL...SEAS WILL FALL THROUGH THE WKND...BECOMING 2-4 FT ON SUNDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR SCZ017-023-024- 032-033-039-053>056. NC...WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ087-096-099- 105>110. MARINE...GALE WARNING UNTIL 6 PM EST THIS EVENING FOR AMZ250-252-254- 256. && $$ NEAR TERM...REK/RJD SHORT TERM...RGZ LONG TERM...JDW AVIATION...DL MARINE...REK/RJD/JDW/RGZ
AREA FORECAST DISCUSSION
NWS BISMARCK ND
348 AM CST WED MAR 6 2013 .SHORT TERM...TODAY THROUGH THURSDAY... THE MAIN CHALLENGE FOR THE SHORT TERM IS THE EVOLUTION OF THE STRATUS TODAY WITH DENSE FOG NORTH CENTRAL ALSO HIGHLIGHTING THE PERIOD THIS MORNING. THE 00 UTC GUIDANCE IS IN GOOD AGREEMENT AND FAVORED A BLEND FOR MOST FIELDS WITH BIAS CORRECTION PREFERRED FOR HIGH TEMPERATURES TO CAPTURE THE IMPACT OF THE SNOWPACK. THE MAIN CORRECTION BEING A REDUCTION OF A COUPLE DEGREES NORTH CENTRAL AND AN INCREASE OF A FEW DEGREES SOUTHWEST AND SOUTH CENTRAL. MAINTAINED THE DENSE FOG ADVISORY THROUGH 15 UTC ACROSS NORTH CENTRAL NORTH DAKOTA AS SURFACE OBSERVATIONS AND WEBCAMS CONTINUE TO INDICATE WIDESPREAD DENSE FOG WITH VISIBILITIES OF ONE QUARTER MILE OR LESS IN THE STRATUS FREE AREAS AS OF 0930 UTC. AS MIXING INCREASES IN THE 12-15 UTC TIME FRAME IN RETURN FLOW ON THE WESTERN PERIPHERY OF THE DEPARTING SURFACE HIGH...THE FOG SHOULD QUICKLY LIFT. OTHERWISE FOR TODAY AS IS USUALLY THE CASE WITH STRATUS...THE QUESTION IS HOW LONG IT WILL REMAIN IN PLACE. THE RAP THROUGH THE OVERNIGHT HAS HAD A GOOD HANDLE ON THE DECKS ACROSS WESTERN THROUGH SOUTH CENTRAL NORTH DAKOTA AND ACROSS THE EASTERN PORTIONS OF THE STATE. THUS...WILL FOLLOW ITS LATEST RUNS FOR CLOUD COVER TODAY...WHICH HOLDS THE STRATUS FIELDS THROUGH THE MORNING AND SLOWLY LIFTS THEM THROUGH THE AFTERNOON. DID ADD A MENTION OF ISOLATED FLURRIES UNDER THE STRATUS BASED ON OBSERVED TRENDS UNDER THE DECK THROUGH THE NIGHT. WITH SOUTHEASTERLY WINDS...A LOW LEVEL INVERSION WILL SETUP ACROSS THE AREA...LIMITING MIXING HEIGHTS AND HIGH TEMPERATURES. GIVEN THE COLD START NORTH CENTRAL THIS MORNING AND THE FRESH SNOW...HIGHS ARE ONLY EXPECTED TO CLIMB INTO THE TEENS. ACROSS THE THINNER SNOWPACK OF THE SOUTHWEST...BELIEVE HIGHS IN THE LOWER 30S ARE POSSIBLE ACROSS THE HIGHER TERRAIN AS MORE AND MORE BARE GROUND BECOMES EXPOSED THROUGH THE DAY. FOR TONIGHT...A TIGHT PRESSURE GRADIENT BETWEEN THE AFOREMENTIONED DEPARTING HIGH AND LOW PRESSURE ACROSS NORTHEAST WYOMING WILL MAINTAIN SOUTHEASTERLY WINDS AROUND 15 KTS FOR MUCH OF THE AREA OVERNIGHT. THUS...TEMPERATURES SHOULD NOT FALL TOO FAR...WITH LOWS NEAR 10 NORTHEAST TO THE UPPER 20S SOUTHWEST. ON THURSDAY A WARM FRONT PROPAGATES INTO WESTERN NORTH DAKOTA AND IS FORECAST TO MAKE IT THROUGH THE HIGHWAY 83 CORRIDOR BY LATE AFTERNOON. FAVORING BIAS CORRECTION TO AID IN THE SNOWPACK IMPACTS...HIGHS SHOULD RANGE FROM THE MID 20S ACROSS THE TURTLE MOUNTAINS TO UPPER 30S SOUTH CENTRAL AND POSSIBLY THE LOWER 40S SOUTHWEST AS INSOLATION FROM TODAY...BREEZY CONDITIONS THROUGH THE OVERNIGHT AND MILD TEMPERATURES ON THURSDAY SHOULD ALL ACT TO QUICKLY EVAPORATE/MELT THE SNOW ACROSS THE SOUTHWEST AND SOUTH CENTRAL. THERE IS A SLIGHT CHANCE OF SNOW MAINLY ALONG AND NORTH OF US HIGHWAY 2 ON THURSDAY AS AN UPPER LEVEL WAVE EJECTS OUT OF THE INTERMOUNTAIN WEST. HOWEVER...THE 00 UTC GUIDANCE HAS TRENDED FURTHER NORTH WITH ANY PRECIPITATION COMPARED TO EARLIER RUNS. LONG TERM...THURSDAY NIGHT THROUGH TUESDAY... THE MAIN FOCUS OF THE LONG TERM PERIOD IS THE POTENTIAL FOR ANOTHER ROUND OF SNOW ON FRIDAY...POSSIBLY LINGERING INTO SATURDAY. MODEL CONSENSUS IS STRONGER TODAY WITH THE LATEST SUITE OF MODELS...REGARDING THE EVOLUTION OF A LARGE WESTERN CONUS TROUGH THROUGH THE PLAINS. CONFIDENCE IS INCREASING IN THE POTENTIAL FOR LIGHT SNOW FRIDAY AFTERNOON AND NIGHT...MAINLY OVER SOUTHERN AND CENTRAL PORTIONS OF THE FORECAST AREA. LATEST WPC GUIDANCE AROUND A COUPLE INCHES THROUGH 12Z SATURDAY SEEMS REASONABLE AT THIS POINT. THERE IS STILL UNCERTAINTY AS TO HOW FAST THE TROUGH WILL EXIT ON SATURDAY...AS THE ECMWF/GFS ARE FASTER AND THE GEM/NAM SUGGEST ADDITIONAL SNOW ACROSS THE SOUTHEAST. HAVE OPTED TO STICK WITH THE FASTER SOLUTIONS AND KEEP CHC POPS LIMITED TO THE FAR SE COUNTIES ON SATURDAY. LOOKING AHEAD...DEVELOPING NORTHWEST FLOW LATE IN THE PERIOD WILL LIKELY RESULT IN PERIODS OF SHORTWAVE ENERGY STREAMING INTO THE STATE...BUT TIMING DIFFERENCES MAKE IT DIFFICULT TO FOCUS ON ANY PARTICULAR PERIOD RIGHT NOW. && .AVIATION... MVFR/IFR STRATUS CONTINUES TO EXPAND ACROSS WESTERN AND CENTRAL NORTH DAKOTA EARLY THIS MORNING...AND IS NOW IMPACTING ALL TAF SITES. DENSE FOG HAS ALSO DEVELOPED AT KMOT AND WILL LIKELY PERSIST UNTIL THE LOW CLOUD SHIELD MOVES IN. EXPECT A FEW FLURRIES THROUGH THE MORNING AS WELL. MVFR CIGS SHOULD LINGER AT KJMS/KDIK THROUGH THE AFTERNOON...WITH DECREASING CLOUDS AT KBIS/KISN/KMOT. && .BIS WATCHES/WARNINGS/ADVISORIES... DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR NDZ002>005- 011>013-021>023. && $$ SHORT TERM...AYD LONG TERM/AVIATION...RK
AREA FORECAST DISCUSSION
NWS BISMARCK ND
104 AM CST WED MAR 6 2013 .DISCUSSION... NO SIGNIFICANT CHANGES WERE REQUIRED WITH THIS FORECAST UPDATE AS THE INHERITED FORECAST WAS WELL ON TRACK AND BLENDED TO THE 0630 UTC OBSERVED TRENDS. SURFACE HIGH PRESSURE WAS IN PLACE ACROSS NORTH CENTRAL NORTH DAKOTA AND INTO THE JAMES RIVER VALLEY. WITH FRESH SNOW AND CLEAR SKIES...SUB-ZERO TEMPERATURES ARE BEING OBSERVED WITHIN THE CENTER OF THE SURFACE HIGH. FOLLOWED CLOSELY TO THE LATEST RAP RUNS FOR OVERNIGHT LOWS AS IT HAS A GOOD HANDLE ON THE TEMPERATURE PATTERN THUS FAR THROUGH THE EARLY OVERNIGHT. THE BIGGEST CHALLENGE FOR TONIGHT WILL BE THE EVOLUTION OF THE STRATUS ACROSS WESTERN AND INTO SOUTH CENTRAL NORTH DAKOTA...WITH A BREAK IN THE DECK UNTIL THE DEVILS LAKE BASIN AND EASTERN PORTIONS OF THE JAMES RIVER VALLEY. AS HAS BEEN THE CASE...THE RAP ALSO HAS A GOOD HANDLE ON THE STRATUS AND WILL FOLLOW ITS LOW LEVEL MOISTURE FIELDS FOR CLOUD COVER THE REMAINDER OF THE NIGHT. FINALLY...INCREASED THE WORDING FROM PATCHY FOG TO AREAS OF DENSE FOG ACROSS THE NORTHWEST AND NORTH CENTRAL BASED UPON SURFACE OBSERVATIONS AND WEBCAMS. && .AVIATION...FOR THE 06Z WEDNESDAY TAF ISSUANCE...ONE STRATUS AREA WITH MVFR CIGS STRETCHING FROM KISN TO KDIK...WHILE A SECOND AREA WAS LOCATED OVER KJMS WITH FLURRIES AND OCCASIONAL REDUCTION TO MVFR VSBYS. STRATUS WAS LOCATED JUST WEST OF KBIS...WITH SKC IN KMOT. PATCHY FOG IS POSSIBLE AT KBIS/KMOT OVERNIGHT...WHILE STRATUS IS FORECAST TO CONTINUE ELSEWHERE AND SLOWLY EXPAND THROUGH 12Z. OVERALL...EXPECT MVFR CIGS AND PATCHY FOG TO PERSIST THROUGH MOST OF WEDNESDAY MORNING. THE MVFR CIGS WILL SLOWLY IMPROVE TO LOW VFR WEDNESDAY AFTERNOON. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...AYD AVIATION...KS
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
655 PM EST THU MAR 7 2013 .SYNOPSIS... LOW PRESSURE OFF THE EAST COAST DRIFTS SLOWLY AWAY THROUGH FRIDAY...ALLOWING HIGH PRESSURE TO BUILD IN THIS WEEKEND. A COLD FRONT AND WAVE OF LOW PRESSURE MOVE THROUGH EARLY NEXT WEEK. && .NEAR TERM /THROUGH FRIDAY NIGHT/... STILL COULD SEE A PEAK OF SUN OR TWO INTO THE KANAWHA VALLEY THIS AFTERNOON...BUT CANNOT ELIMINATING THE LOW LEVEL MOISTURE IN PLACE DOWNWIND OF THE GREAT LAKES. RUC HAS THE STRATUS DECK THROUGH 05Z TONIGHT...AND OTHER MODELS DRYING OUT THE WESTERN LOWLANDS AFTER 06Z. THE SUN MAKES AN APPEARANCE FRIDAY WITH HIGH PRESSURE DRIFTING ACROSS THE SOUTHERN GREAT LAKES AND DRYING LOW LEVELS. NAM AT 925MB STILL HAS NORTHERLY FLOW AND SATURATION IN A LINGERING THERMAL TROUGH...SO KEPT THE CLOUDS IN PLACE OVER THE TYGART AND GREENBRIER VALLEYS. WILL SEE A SLOW IMPROVEMENT TO THE 850MB TEMPERATURES...BUT WILL NOT QUITE GET INTO THE EFFICIENT WARM UP WITH A NORTHERLY COMPONENT TO THE WIND AT THE SURFACE AN LOW LEVELS THROUGH 00Z SATURDAY. && .SHORT TERM /SATURDAY THROUGH SUNDAY/... HIGH PRESSURE IS IN CONTROL AT THE SURFACE FOR THE FIRST HALF OF THE WEEKEND...WITH A RIDGE BUILDING IN ALOFT. THIS WILL SPELL ABOVE NORMAL AFTERNOON HIGHS ACROSS MUCH OF THE FORECAST AREA. HIGHS MAY BE TEMPERED A BIT BY LINGERING SNOW COVER IN THE NORTHERN MOUNTAINS OF WEST VIRGINIA SO STAY A BIT BELOW GUIDANCE THERE. MODEL TIMING A LITTLE DIFFERENT ON WHEN THE LEADING PRECIP AHEAD OF THE NEXT SYSTEM MAY ENTER OUR WESTERN ZONES. ONLY MADE LITTLE CHANGES FROM PREVIOUS POP FORECAST...WITH SLIGHT CHANCE POPS ENTERING FROM THE WEST SATURDAY AFTERNOON. DESPITE INCREASING HIGH CLOUDS...SUNDAY SHOULD BE THE WARMER DAY OF THE WEEKEND...WITH LOW TO MID 60S PRETTY WIDESPREAD ACROSS THE LOWER ELEVATIONS...AND UPPER 40S TO 50S IN THE MOUNTAINS AS SNOW PACK CONTINUES TO MELT. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MOISTURE FROM THE LEADING EDGE OF THE NEXT FRONTAL SYSTEM WILL BEGIN TO SPREAD OVER THE WESTERN PORTIONS OF THE FORECAST AREA LATE SUNDAY NIGHT AS THE WEEKENDS UPPER LEVEL RIDGE SLIDES EAST INTO THE ATLANTIC. RAINFALL WILL BECOME MORE WIDESPREAD THROUGH THE DAY MONDAY AS A FRONTAL SYSTEM WITH A GOOD SOUTHERLY FETCH SHIFTS EAST. WITH TEMPERATURES REMAINING WARM DURING THIS TIME PERIOD WILL NEED TO WATCH THE FRONT CLOSELY FOR HYDRO CONCERNS. SO FAR MODELS ARE SHIFTING IT EAST QUICKLY ENOUGH TO KEEP PRECIPITATION AMOUNTS IN THE INCH RANGE BUT IF WAVES END UP FORMING ALONG THE FRONTAL BOUNDARY AND IT STALLS...THE NORTH TO SOUTH ORIENTATION OF THE SYSTEM WOULD BE FAVORABLE FOR PICKING A GOOD BIT MORE RAIN. AGAIN AT MOMENT IT DOES NOT LOOK LIKE THE FRONT WILL STALL BUT RATHER JUST SOMETHING TO WATCH. COOLER AIR WILL SWING DOWN BEHIND THE FRONTAL MIDWEEK BUT LOOKS FAR ENOUGH BEHIND THAT MOST OF THE LINGERING POST FRONTAL SHOWERS WILL BE OVER WITH BY THEN. && .AVIATION /00Z FRIDAY THROUGH TUESDAY/... LOW LEVEL MOISTURE PERSISTENT AND CONTINUES TO CAUSE DIFFICULTIES FIGURING OUT NOCTURNAL TRENDS OVERNIGHT. THERMAL TROF AT 925 TO 850 MB FINALLY BEGINS TO MODERATE AFTER 15Z...FORECASTING CLOUDS BECOMING SCATTERED TO BROKEN BY 18Z. WILL TRY TO LOWER CEILINGS 03Z TO 07Z WITH THE NOCTURNAL COOLING...WITH WIDESPREAD CEILINGS 1 TO 2 THSD FT AFTER 06Z THROUGH 14Z. FLURRIES AND LIGHT SNOW SHOWERS MAY ACTUALLY INCREASE CKB TO EKN AND CENTRAL WV MOUNTAINS BETWEEN 02Z THROUGH 06Z THEN DECREASE AGAIN TOWARD 12Z. VSBY 3 TO 5 MILES IN THE SNOW SHOWERS. HAVE CLOUDS THINNING 09Z TO 12Z...BREAKS IN CLOUDS MAY CAUSE SOME AREAS OF MVFR IN HAZE AND LIGHT FOG THRU 14Z. CONSIDERING BOUNDARY LAYER WINDS SHOULD CONTINUE TO BLOW FROM THE NORTH...WAS NOT FORECASTING ANY THICK FOG. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z SATURDAY... FORECAST CONFIDENCE...MEDIUM. ALTERNATE SCENARIOS: WITH THE SATURATED LOW LEVELS...CEILING HEIGHTS MAY VARY...EITHER HIGHER OR LOWER...FROM FORECAST...WITH 06Z TO 14Z FRIDAY THE MOST VULNERABLE PERIOD. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE FRI UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11 EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06 CRW CONSISTENCY H M M M M H L L L L L L HTS CONSISTENCY H M M M M M M H L L L L BKW CONSISTENCY H H M M L L L L L L L L EKN CONSISTENCY L L L L L L L L L L L L PKB CONSISTENCY H H H H H H H H M M M M CKB CONSISTENCY L L H M M H H H H M L L AFTER 00Z SATURDAY... IFR POSSIBLE IN RAIN SHOWERS MONDAY INTO MONDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...MZ/26/JR NEAR TERM...26 SHORT TERM...MZ LONG TERM...JR AVIATION...KTB
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
108 AM EST WED MAR 6 2013 .SYNOPSIS... LOW PRESSURE PUSHES THROUGH OVERNIGHT...CHANGING RAIN TO SNOW. SNOW ON ITS BACKSIDE WEDNESDAY. UPSLOPE SNOW UNDER NORTHWEST FLOW INTO THE END OF THE WEEK NORTHEAST MOUNTAINS. HIGH PRESSURE BY WEEKEND. && .NEAR TERM /UNTIL 9 AM THIS MORNING/... UPDATED WIND DIRECTION...SPEED AND GUST AFTER EXTRAPOLATING SFC LOW CENTER FROM THE RUC TO MATCH SFC OBS AND RADAR LOOP. REST OF FORECAST REMAINS ON TRACK WITH PCPN CHANGING TO ALL SNOW BY 05Z. PREVIOUS FORECAST BELOW... 930 PM UPDATE... NEAR TERM TRENDS INCLUDING FASTER FALL ON TEMPERATURES WARRANT STARTING THE ADVISORY FOR CENTRAL WV MOUNTAINS AND THE NORTHERN WV LOWLANDS EARLIER. ALSO HAVE SLIGHTLY HIGHER SNOWFALL AMOUNTS FOR THE NORTHERN MOUNTAINS OVERNIGHT GIVEN LOWER TEMPERATURES THERE. ENHANCED WIND GUSTS TUG FORK / COAL FIELDS AREA AND EVEN INTO THE HTS TRI-STATE AREA...ALL S OF THE LOW TRACK. 630 PM UPDATE... COMPLEX FCST BY AND LARGE ON TRACK AS LOW PRESSURE ENTERS THE AREA ALONG THE OHIO RIVER. PREV DISCN... PRECIPITATION SLOW IN PUSHING INTO THE CWA AFTER THE FIRST BATCH DISSOLVED OUT SO...TRIMMED BACK SOME OF THE POPS OVER THE NORTHERN ZONES OVER THE NEXT FEW HOURS UNTIL SHIELD ACCELERATES THROUGH. USED THE LOCAL WRF MODELS TO ACCOUNT FOR THIS TIMING. BIGGEST KEYS TO THE FORECAST TODAY ARE THE TIMING OF THE TEMPERATURE DROPS TO AND BELOW FREEZING TONIGHT AND THE POTENTIAL OF LOW LEVEL SUBSIDENCE OVER THE LOWLANDS NEAR 12Z WEDNESDAY. REGARDING THE FORMER...MODELS WERE VERY SLUGGISH IN BRINGING THE TEMPERATURES DOWN TO FREEZING FOR THE TRANSITION TO FROZEN PRECIPITATION. WEARY OF THIS TEMPERATURE GUIDANCE UNDERDOING THE DYNAMIC COOLING ASPECT...SO NUDGED THE HOURLIES DOWN A COUPLE DEGREES DURING THE TONIGHT TIME PERIOD. THIS DOES NOT INCLUDE THE MOUNTAINS...AS THESE LOCATIONS WERE COOL ENOUGH. AS THE SNOWFALL BEGINS...WILL HAVE THAT LAG PERIOD WHERE RAIN AND SLOWLY COOLING AIR WILL HINDER ACCUMULATIONS. COULD START AS SLUSHY ACCUMULATIONS AT FIRST...ESPECIALLY FOR THE LOWLANDS. TRANSITION FOR THE HIGHER ELEVATIONS AND SUBSEQUENT ACCUMULATIONS LOOKS TO BE MORE EFFICIENT. BUT THERE WILL STILL BE A HEAVY AND WET NATURE TO THE SNOW. GFS AND NAM DEPICT SUBSIDENCE AT THE 700MB...AND VERY LITTLE LIFT AT 850MB OVER THE LOWLANDS...PARTICULARLY THE TRI STATE AREA. THEREFORE...FEEL THE BULK OF THE SNOW...WHICH ARE GENERALLY AN INCH OR LESS OVER THE CHARLESTON TO HUNTINGTON CORRIDOR...WILL FALL PRIOR TO 12Z. POPS COME DOWN TO CHANCE AT THIS TIME. THIS IS NOT THE CASE FOR THE NORTHERN TIER OF COUNTIES AND ALONG AND INCLUDING THE MOUNTAINS...WHERE ACCUMULATIONS WILL CONTINUE WELL INTO THE SHORT TERM. NO ADJUSTMENTS TO THE HEADLINES AT THIS TIME. && .SHORT TERM /9 AM THIS MORNING THROUGH THURSDAY NIGHT/... PRECIPITATION SHOULD MAINLY BE IN THE FORM OF SNOW BY THE START OF THE SHORT TERM PERIOD...AS UPPER LOW MOVES OFF TO THE SOUTH AND EAST OF THE CWA. STILL EXPECTING SOME DECENT ACCUMULATIONS...MAINLY IN THE 12Z TO 18Z TIME FRAME...AS MODELS INDICATING GOOD DENDRITE GROWTH AND DYNAMICS CONTINUING DURING THIS PERIOD. HOWEVER...AS THE DAY PROGRESSES...AND THE LOW PULLS FURTHER AWAY...THIS WILL CHANGE AS MOISTURE DEPTH AND DYNAMICS DECREASE. MAY EVEN SEE A TRANSITION TO DZ OR FZDZ LATER ON WEDNESDAY ACROSS SOME OF THE LOWLANDS IN PARTICULAR AS LAYERS ABOVE 700MB GRADUALLY DRY OUT. FOR NOW THOUGH...WILL JUST TRANSITION TO LIGHT SNOW SHOWERS WITH LITTLE TO NO ACCUMULATIONS ACROSS LOWLANDS...WITH LIGHT ADDITIONAL ACCUMULATIONS ACROSS MOUNTAIN ZONES IN THE NW UPSLOPE FLOW. IN ADDITION TO PRECIPITATION...STILL LOOKING AT DECENT WINDS DEVELOP...PARTICULARLY ACROSS MOUNTAINOUS COUNTIES AS PRESSURE GRADIENT TIGHTENS...AND STRONGER WINDS ALOFT DEVELOP. AS STATED IN PREVIOUS FORECASTS...THIS WILL BE A RATHER HEAVY WET SNOW DURING THE PERIOD. AS THE LOW CONTINUES TO PULL OFF TO THE EAST ON WEDNESDAY...WILL SEE A TRANSITION TO LIGHT UPSLOPE SNOW SHOWERS...WITH ADDITIONAL LIGHT ACCUMULATIONS EXPECTED. GUIDANCE SEEMS TO BE RUNNING A LITTLE HIGH DURING THE PERIOD...PARTICULARLY ON WEDNESDAY MAX T...AND ELECTED TO KEEP TEMPERATURES BELOW GUIDANCE ON THIS DAY AS LOW WILL CONTINUE TO PUSH TO SOUTH AND EAST...BRINGING IN COLDER AIR...AND AS PLENTY OF CLOUD COVER WILL LINGER DURING THE DAY WEDNESDAY. DESPITE REMAINING BELOW GUIDANCE...DO HAVE MUCH OF THE LOWLAND COUNTIES INCHING ABOVE FREEZING ON WEDNESDAY. && .LONG TERM /FRIDAY THROUGH TUESDAY/... MODELS SHOWING UPSLOPE SNOW SHOWERS ENDING IN THE MOUNTAINS ON FRIDAY. HIGH PRESSURE THEN BUILDS IN FOR THE BEGINNING OF THE WEEKEND. MODELS HAVE A LOT OF SPREAD WITH TIMING OF THE NEXT SYSTEM EARLY NEXT WEEK. USED A ECMWF/GEFS ENSEMBLE MEAN BLEND...WHICH PUTS THE TIMING BETWEEN THE GFS AND ECMWF. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... PCPN HAS CHANGED TO ALL SNOW ACROSS THE ENTIRE AREA BY 05Z. PERIODS OF IFR UNDER BURSTS OF SNOW ARE LIKELY TO SPREAD FROM SOUTH TO NORTH AS THE LOW PRESSURE MOVE ROUGHLY NORTHEAST ACROSS PKB THROUGH 12Z. OTHERWISE...MVFR UNDER LIGHT SNOW WILL PREVAIL THROUGH 09Z...DETERIORATING THROUGH 12Z. BIG CHALLENGE TO FORECAST WIND DIRECTION AS WIND WILL CONTINUALLY BACK AS THE LOW MOVES ACROSS. GUSTY WINDS ARE ALSO LIKELY IN THE PERIPHERY OF THE LOW CENTER...BEING WEAKER ALONG THE CENTERS TRACK AND AT PROTECTED MOUNTAIN VALLEYS SUCH AS EKN. THE PRECIPITATION WILL BECOME LIGHTER AND MORE INTERMITTENT WED MORNING...ALLOWING VSBYS TO IMPROVE TO MVFR AT LEAST AT TIMES WED MORNING. CIGS AND VSBYS MAY IMPROVE TO VFR ALONG AND W OF THE OHIO RIVER BY LATE WED AFTERNOON...WHILE MVFR VSBYS AND CIGS REMAIN IN THE MOUNTAINS IN SNOW SHOWERS. SOUTH OF THE LOW...GUSTY SOUTHEAST FLOW WILL BECOME SOUTHWEST OVERNIGHT AND THEN GUSTY NORTHWEST WED MORNING. GUSTY NORTHWEST FLOW THROUGHOUT THE AREA WED AFTERNOON. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 06Z THURSDAY... FORECAST CONFIDENCE...MEDIUM. ALTERNATE SCENARIOS: WIND DIRECTIONS AND SPEEDS WILL BE HIGHLY VARIABLE...AND COULD BE INCONSISTENT FROM HOUR TO HOUR. CEILINGS COULD BOUNCE FROM MVFR TO IFR AS WIND SPEEDS AND INTENSITY OF SNOW CHANGE. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. DATE WED 03/06/13 UTC 1HRLY 06 07 08 09 10 11 12 13 14 15 16 17 EST 1HRLY 01 02 03 04 05 06 07 08 09 10 11 12 CRW CONSISTENCY L L L L L L L L L L H H HTS CONSISTENCY M M M M M M M L H H H H BKW CONSISTENCY L L L L M M M M M M L L EKN CONSISTENCY M M M M M M M M M M M M PKB CONSISTENCY L L M M M M M L L H H H CKB CONSISTENCY M M M M M M M M M M M M AFTER 06Z THURSDAY... IFR VISIBILITIES AND CEILINGS POSSIBLE IN SNOW SHOWERS WED NT INTO THU...ESPECIALLY IN THE WV MOUNTAINS. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR WVZ009>011-019. WINTER WEATHER ADVISORY UNTIL 1 AM EST THURSDAY FOR WVZ020-028- 030>032-035>037-039-040. WINTER STORM WARNING UNTIL 1 AM EST THURSDAY FOR WVZ038-046- 047. OH...WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR OHZ066-067-075-076. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/RPY/SL/26 NEAR TERM...ARJ/TRM/26 SHORT TERM...SL LONG TERM...RPY AVIATION...ARJ
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1220 AM EST WED MAR 6 2013 .SYNOPSIS... A WINTER STORM WILL AFFECT THE AREA TONIGHT AND EARLY WEDNESDAY. HIGH PRESSURE WILL BUILD ACROSS THE REGION LATE THIS WEEK...LASTING INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... MADE SOME MINOR TWEAKS TO STORM TOTAL SNOW AND MADE ADJUSTMENTS TO THE WEATHER GRIDS DURING THIS EVENING UPDATE. ALSO INCREASED WINDS ACROSS THE SOUTH AND WEST AS SURFACE PRESSURE GRADIENT HAS INCREASED ACROSS THE SOUTH...AND WILL LATER TONIGHT ACROSS THE WEST. THIS WILL PRODUCE GUSTS OVER 30 MPH AT TIMES DURING THE OVERNIGHT PERIOD FOR THOSE ZONES. RAIN/SNOW LINE HAS PROGRESSED TO JUST WEST OF THE COLUMBUS AREA. PRECIPITATION WILL CONTINUE TO TRANSITION TO SNOW ACROSS THE FAR EASTERN ZONES TOWARD MIDNIGHT...WITH ALL SNOW FOR THOSE ZONES BY MIDNIGHT. HAVE HAD REPORTS OF ISOLATED THUNDER ASSOCIATED WITH A STRONGER SNOW BAND EXTENDING FROM DARKE COUNTY...SOUTHEASTWARD ACROSS WARREN COUNTY. THESE THUNDER OCCURRENCES ARE ISOLATED IN NATURE. THEREFORE...WILL HOLD OFF ON ADDING THE MENTION OF IT IN THE GRIDS ATTM. THE PEAK SNOW INTENSITY WILL BE FROM NOW UNTIL A COUPLE OF HOURS AFTER MIDNIGHT...AS THE BEST LIFT PRODUCES THE HIGHEST RATES OF ACCUMULATION IN OUR AREA. .PREVIOUS DISCUSSION AT 423 PM EST... AN UPPER LOW IS DIVING SOUTHEASTWARD OUT OF THE NORTHERN PLAINS AND INTO THE TENNESSEE VALLEY THIS EVENING. A SURFACE LOW DEVELOPING OVER KENTUCKY...OUT AHEAD OF THE UPPER LOW WILL DEEPEN AND PIVOT NORTHEASTWARD OVER THE OHIO VALLEY AS THE UPPER LOW SLIDES BY TO THE SOUTH TONIGHT. PRECIPITATION IS ALREADY SPREADING NORTHWARD ACROSS THE FORECAST AREA AHEAD OF THE INTENSIFYING SURFACE LOW. PRECIPITATION WILL FALL AS RAIN ACROSS THE AREA INTO THE EARLY EVENING...AS WARM AIR IS DRAWN NORTH AND WEST INTO THE LOW LEVELS AROUND THE LOW. THE FORECAST FOR LATER THIS EVENING BECOMES COMPLICATED...AS COLD AIR BEGINS TO WORK ITS WAY BACK INTO THE LOW. THIS PROCESS WILL BE TWOFOLD. LOW LEVEL COLD ADVECTION WILL ALLOW FOR COLDER AIR TO WRAP INTO THE SURFACE LOW. AT THE SAME TIME...ABUNDANT VERTICAL MOTION WILL PROVIDE FOR DYNAMIC COOLING FROM THE MIDDLE LEVELS...PROPAGATING TO THE SURFACE. MODELS ARE IN AGREEMENT ON THE STRONG VERTICAL MOTION ASSOCIATED WITH THIS SYSTEM THIS EVENING ACROSS OUR AREA. HOWEVER...THERE ARE CRITICAL DIFFERENCES IN HOW THE MODELS ARE HANDLING THE BATTLE BETWEEN DYNAMIC COOLING...AND WARM AIR BEING PULLED IN AROUND THE LOW. BASED ON HOW STRONG ASCENT IS AS HEAVIER PRECIPITATION MOVES IN THIS EVENING...THIS FORECAST PACKAGE WENT WITH A MODERATELY FAST CHANGEOVER TO SNOW TO BEGIN IN THE WESTERN ZONES AROUND 7 PM...SPREADING EAST THROUGH THE DAYTON/CINCY AREAS BY 9 PM...THEN COLUMBUS BY 10 OR 11 PM. IF THE DYNAMIC COOLING PROCESS IS STRONGER THAN THIS FORECAST IS HINTING AT...THEN THIS CHANGEOVER WILL OCCUR SOONER...WITH THE RESULT BEING HIGHER SNOW TOTALS. OF COURSE...IF ADDITIONAL WARMER AIR IS DRAW INTO THE SYSTEM...LIKE THE RAP SUGGESTS THEN MORE RAIN WILL FALL INITIALLY. THE RAP SOLUTION HAS BEEN ON THE WARM SIDE TODAY...THEREFORE AM LEANING TOWARD THE COLDER SOLUTIONS. ANY SNOW THAT OCCURS JUST AFTER THE CHANGEOVER WILL BE A HEAVY...WET SNOW. THE BOTTOM LINE IS THAT THE MODELS LOOK AS IF THEY ARE PICKING UP ON THE STRONGER LIFT BASED ON QPF AMOUNTS RISING OVER RECENT RUNS. THIS MEANS A POTENTIAL FOR HIGHER STORM TOTALS FOR OUR AREA. TOTAL SNOWFALL NUMBERS WERE THEREFORE TWEAKED SLIGHTLY HIGHER...WITH THE MAXIMUM BEING AROUND 8 INCHES STORM TOTAL ACROSS THE NORTHWESTERN ZONES. SOME OF THE SOUTHWESTERN ZONES...WHERE A TRANSITION WILL OCCUR FIRST...MAY RECEIVE UP TO 4 INCHES OF SNOW. THE TRICKIEST SNOWFALL TOTAL FORECAST LIED WHERE THE CENTER OF THE SURFACE LOW IS EXPECTED TO SPIN FOR A FEW HOURS TONIGHT...ACROSS THE SCIOTO VALLEY. THERE...SNOWFALL AMOUNTS COULD VARY QUITE A BIT...NOT ONLY DUE TO THE DELAYED CHANGEOVER DUE TO SOME WARMER AIR...BUT THE LACK OF HEAVIER QPF UNDERNEATH THE LOW`S CENTER LATE TONIGHT. EXPANDED THE WINTER STORM WARNING TO INCLUDE SOME OUR OUR NORTHERN KENTUCKY ZONES THAT ARE NOW EXPECTED TO REACH OUR 12 HOUR CRITERIA OF 4 INCHES OF SNOW TONIGHT. DID DELAY THE START OF ALL WARNINGS/ADVISORY EXCEPT ACROSS THE EXTREME NORTH...SINCE THAT WARNING WAS ALREADY IN EFFECT AT THE TIME OF THE FORECAST PACKAGE ISSUANCE. SNOW WILL CONTINUE THROUGHOUT THE EARLY PRE-DAWN HOURS AS THE SURFACE LOW SPINS ACROSS SOUTHEASTERN OHIO. && .SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY NIGHT/... THE UPPER LOW WILL QUICKLY SHIFT TOWARD THE MID ATLANTIC STATES WEDNESDAY MORNING AS A SECONDARY SURFACE LOW DEVELOPS CLOSER TO THE EASTERN SEABOARD. THIS ENERGY TRANSFER EASTWARD...AND AWAY FROM OUR AREA WILL BRING A RAPID END TO FORCING SUPPORTING STEADY SNOW IN OUR AREA. SNOW WILL TAPER OFF QUICKLY AROUND SUNRISE WITH ONLY SOME LIGHTER SNOW SHOWERS EXPECTED DURING THE DAY. NORTHERLY FLOW BEHIND THE DEPARTING STORM SYSTEM AND RIDGING ACROSS THE NORTHERN PLAINS WILL KEEP A CHANCE FOR LIGHT SNOW OR FLURRIES IN OUR AREA THROUGH WEDNESDAY NIGHT AND INTO THE DAY THURSDAY. TEMPERATURES DURING THIS TIME PERIOD WILL REMAIN BELOW NORMAL. LOW LEVEL MOISTURE...AND ASSOCIATED CLOUD COVER WILL FINALLY BEGIN TO GIVE WAY TO DRIER CONDITIONS THURSDAY NIGHT...AS THE RIDGE BUILDS ACROSS THE OHIO VALLEY. TEMPERATURES WILL LIKELY BOTTOM OUT THURSDAY NIGHT IN THE UPPER TEENS TO LOW 20S UNDER PARTLY CLOUDY SKIES. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AFTER A PLEASANT AND GENERALLY MILD WEEKEND...WITH GOOD MODEL AGREEMENT...THERE IS CONSIDERABLE UNCERTAINTY ON A WEATHER SYSTEM MOVING INTO THE REGION EARLY NEXT WEEK. THE WEEKEND WILL BEGIN WITH A MID LEVEL TROUGH AXIS EXTENDING FROM THE GULF OF MEXICO TO NORTHERN INDIANA. WARM ADVECTION WILL BE UNDERWAY ALOFT...AND SHOULD BEGIN AT THE SURFACE AS WELL (AS WINDS TAKE A SOUTHERLY COMPONENT). THIS PATTERN WILL GENERALLY CONTINUE INTO SUNDAY...AS THE RIDGE AXIS MOVES EAST. WITH QUITE A BIT OF SUN ON SATURDAY (PERHAPS JUST SOME LOW CLOUDS THAT ARE SLOW TO MOVE OUT OF THE NORTHEASTERN CWA)...TEMPERATURES WILL RISE ABOVE NORMAL BY ABOUT 5 DEGREES. THE RIDGE WILL CONTINUE TO DOMINATE THE WEATHER ON SUNDAY...BUT AS INFLUENCE FROM THE DEVELOPING WEATHER SYSTEM IN THE WESTERN STATES BEGINS TO COMPLICATE THE FORECAST...SOME UNCERTAINTY WILL BEGIN TO SET IN. MOISTURE WILL BEGIN TO ADVECT IN ALOFT...LEADING TO HIGH CLOUDS THICKENING THROUGH THE DAY. DESPITE THIS...SURFACE WARM ADVECTION WILL BE STRENGTHENING...LEADING TO EVEN WARMER TEMPS ON SUNDAY. BEYOND SUNDAY...A VERY HIGH AMOUNT OF UNCERTAINTY EXISTS IN THE FORECAST. IT APPEARS CERTAIN THAT A WESTERN TROUGH WILL EJECT INTO THE EASTERN STATES...AS SURFACE LOW PRESSURE DEVELOPS AND MOVES THROUGH OR NEAR THE OHIO VALLEY. HOWEVER...THERE IS VERY LOW CONFIDENCE IN THE TIMING OF THIS SYSTEM...AS WELL AS IN THE PLACEMENT OF THE SURFACE LOW. DETERMINISTIC MODELS (12Z GFS VS 12Z CMC VS 00Z ECMWF) ARE AS MUCH AS A DAY AND A HALF OFF IN TIMING...WITH THE SURFACE LOW POSSIBLY GOING NORTH OR SOUTH OF THE AREA. SO...AT THIS TIME...THE FORECAST WILL REMAIN VERY GENERAL. ALTHOUGH IT IS FRUSTRATING TO GO NO HIGHER THAN 30 POPS WHEN RAIN APPEARS A VIRTUAL CERTAINTY AT SOME POINT IN THE SUNDAY NIGHT THROUGH TUESDAY TIME FRAME...THE TIMING DIFFERENCES ARE TOO GREAT TO GO HIGHER. && .AVIATION /05Z WEDNESDAY THROUGH SUNDAY/... A DYNAMIC STORM SYSTEM WILL CONTINUE TO AFFECT THE REGION THROUGH 12Z WITH SNOW AND WIND. SURFACE LOW PRESSURE OVER SOUTHEAST OHIO THIS MORNING WILL BEGIN TO WEAKEN OVER SOUTHEAST OHIO BETWEEN 09Z AND 12Z AS PARENT UPPER LEVEL LOW PUSHES EAST TOWARD THE MID ATLANTIC...ALLOWING A STRONGER SURFACE LOW DEVELOP NEAR THE COAST. THIS IS THE TYPICAL ENERGY TRANSFER WE SEE IN THE OHIO VALLEY. SNOW...MODERATE TO LOCALLY HEAVY AT TIMES...SHOULD QUICKLY TAPER OFF FROM NW TO SOUTHEAST BY SUNRISE. CONDITIONS WILL REMAIN CLOSE TO AIRFIELD MINIMUMS UNTIL THE SNOW TAPERS OFF. THEREAFTER...SKIES WILL REMAIN MOSTLY CLOUDY TO CLOUDY WITH VSBYS IMPROVING TO VFR AND CEILINGS REMAINING IN THE MVFR RANGE BETWEEN 1500 AND 2000 FEET. GUSTY NORTH WINDS WILL BEGIN TO TAPER OFF TOWARD 00Z THURSDAY. OUTLOOK...MVFR CEILINGS TO LINGER INTO THURSDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR OHZ026- 034-035-042>046-051>056-060>065-070>072-077>080. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR OHZ073-074-081-082-088. KY...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR KYZ089>093. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR KYZ094>100. IN...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR INZ050- 058-059-066-073>075-080. && $$ SYNOPSIS...LATTO NEAR TERM...LATTO SHORT TERM...LATTO LONG TERM...HATZOS AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
436 AM EST WED MAR 6 2013 .SYNOPSIS... LOW PRESSURE OVER SOUTHERN OHIO WILL WEAKEN AS A SECONDARY LOW DEVELOPS OVER THE SOUTHERN MID-ATLANTIC PIEDMONT EARLY THIS MORNING. THE LOW WILL TRACK SLOWLY NORTHEAST TO THE VIRGINIA TIDEWATER REGION THIS AFTERNOON AND MOVE OFF THE DELMARVA PENINSULA BY THIS EVENING. THIS COMPLEX STORM SYSTEM WILL BRING MODERATE TO HEAVY SNOW TO SOUTH-CENTRAL PENNSYLVANIA. HIGH PRESSURE WILL BUILD IN FROM THE WEST FOR THE WEEKEND WITH FAIR WEATHER AND TEMPERATURES RISING TO NEAR NORMAL. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... RADAR AND SATL LOOP SHOW WELL-DEFINED COMMA HEAD/DEFORMATION PCPN BAND SPREADING NWD INTO SRN PA AS UPPER LOW AND ASSOCD HT FALLS APPROACH THE SPINE OF THE N-CENTRAL APPALACHIANS. 06Z RUC SFC ANALYSIS SHOWS PRIMARY/OCCLUDED LOW OVER SRN OH WITH SECONDARY LOW DEVELOPING OVER THE NC/VA PIEDMONT IN RESPONSE TO 2-4MB 3HR PRES FALLS. AS THE SECONDARY LOW BEGINS TO TRACK SLOWLY TO THE NE EARLY THIS MORNING...EXPECT INCREASING FGEN FORCING TO SUPPORT OCNL 1-1.5 IN/HR SNFL RATES OVR FAR SWRN/S-CENTRAL PA AS THE SNOW BAND CONTINUES TO PUSH NORTH ACRS THE MASON DIXON LINE. ALTHOUGH TEMPS ARE STILL A FEW DEGS ABOVE 32F IN SOME AREAS...EXPECT WET BULB/NOCTURNAL EFFECTS AND ISALLOBARIC FORCING/COLDER NLY FLOW TO RESULT IN ALL SNOW PTYPES. EXTRAPOLATION OF RADAR TRENDS ALONG WITH CONSENSUS OF HI-RES MDLS SHOWS THE NRN EDGE OF THE SNOW CONFINED ALONG AND SOUTH OF IDI-LNS LINE THRU AT LEAST THE NEXT FEW HOURS/09Z WITH A SLIGHT NWD SHIFT LKLY BY 12Z. A VERY SHARP GRADIENT WILL MAKE FOR A DIFFICULT SPATIAL FCST WITH SNOW/NO SNOW OBS OVER A VERY SHORT N-S DISTANCE. EXPECT SEVERAL INCHES OF ACCUM /2-4" IN 6 HRS/ BY DAYBREAK FROM SOMERSET COUNTY EWD TOWARD SOUTH MTN. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM THURSDAY/... GUIDANCE CURRENTLY TRENDING A LITTLE FARTHER TO THE SOUTH AND FURTHER DECREASES PRECIP AMOUNTS OVER THE AREA. BUT THIS COULD JUST BE THE LATEST WAGGLE. HOWEVER...WE ARE FULLY INTO THE REALM OF THE SHORT RANGE MODELS AT THIS MOMENT. SO...CONFIDENCE IS HIGH ON THE AMOUNTS FROM A BLEND OF THE NAM/GFS/SREF. HEAVY SNOW MOST LIKELY IN THE LAURELS AND ALONG THE MD BORDER WHERE THE HIGHEST INFLUX OF MSTR FROM THE EAST IS POINTED. THE TREMENDOUS EASTERLY FLOW WILL CREATE A HIGHLY ANOMALOUS 8H POSITIVE MOISTURE FLUX AREA OVER THE SRN COUNTIES DURING THE MORNING AND EARLY AFTN IN OUR SRN COS. THE EXPECTED MESOSCALE HEAVY BANDS OF SNOW WILL BE CAPABLE OF MAKING INCH OR MORE PER HOUR RATES. SO EVEN A SHORTER TIME IN THE FAVORED SNOWFALL PERIOD - NOW MORE LIKE 12-18HRS RATHER THAN A FULL 24 HRS - KEEPS US JUST AS LIKELY TO GET 6 INCHES OR MORE OF ACCUM ACROSS THE SOUTH. THE STORM CENTER WILL BE ALMOST FULLY TRANSITIONED TO THE SECONDARY CENTER AT THE BEGINNING OF THE PERIOD. THE TRACK MADE BY THE STRONG CONSENSUS OF THE DETERMINISTIC MDLS AND ENSEMBLE MEMBERS TAKES IT OUT TO SEA FAR ENOUGH BY WED NIGHT TO DECREASE THE POPS IN THE WEST WED AFTN...AND IN THE EAST AROUND MIDNIGHT. HOWEVER...A POSSIBLE NORTHWARD CURVE TO THE STORM WEDNESDAY EVENING WHEN IT IS WELL OF THE COAST COULD DELAY THE EXIT OF VERY LIGHT PRECIP FROM THE EASTERN COUNTIES UNTIL LATE WED NIGHT. TEMPS ARE AN INTERESTING PART OF THIS FCST - WITH WIDESPREAD 30-33F TEMPS AS THE PRECIP OCCURS. THIS WILL LIKELY CREATE A SOMEWHAT ELEV-DEPENDENT SNOW FALL. LANCASTER CO AND THE LOWER ELEVS OF YORK/DAUPHIN/LEBANON CO WILL BE MOST AT-RISK TO SEE A LITTLE RAIN MIX IN LATE WED/EARLY WED NIGHT. WILL DRAW SNOW ACCUM MAP MORE BROAD- BRUSHED THOUGH FOR SIMPLICITY/S SAKE. THIS ALSO KEEPS A VERY STRONG CONTINUITY IN THE FORECAST SNOW AMOUNTS. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... LARGE STORM SYSTEM SLIDES OFF EAST COAST BY THURSDAY...WHILE A CHILLY AND RATHER GUSTY NORTHERLY FLOW ARRIVES WITH ISOLATED TO SCATTERED MTN SNOW SHOWERS. AFTER THAT...HEIGHTS BEGIN TO RISE ON FRI...WITH DAYTIME TEMPS MODERATING TO SEASONAL NORMALS THROUGH THE WEEKEND. WARMING TREND CONTINUES INTO EARLY NEXT WEEK...BUT WITH SIGNIFICANT MODEL DIVERGENCE DEVELOPING IN LONGER TERM MODELS. BUT GENERAL PATTERN KEEPS BROAD MILDER WESTERLY FLOW TO EASTERN U.S. WITH A WEAKENING LOW LIFTING ACROSS THE NORTHEAST MON NIGHT INTO TUE INCREASING CHANCES FOR PRIMARILY RAIN SHOWERS. && .AVIATION /09Z WEDNESDAY THROUGH SUNDAY/... SNOW SHOWERS ARE CURRENTLY STREAMING FROM THE SOUTH ENVELOPING PA THIS MORNING. LIFR CONDITIONS AT JST AND AOO WILL CONTINUE THROUGH THE FIRST HALF OF THE DAY...BEFORE SUBSIDING BY 18Z. EXPECT MVFR TO IFR CIGS TO CONTINUE THROUGH MOST OF THE DAY. THE LOW LEVEL MOISTURE COULD ALLOW FOR IFR AND LOWER CIGS TONIGHT. ELSEWHERE THE SNOW IS CURRENTLY BRINGING MVFR CIGS AND VSBYS TO MDT...AND MVFR CIGS OUT AHEAD OF THE SYSTEM AT UNV. IFR CONDITIONS ARE EXPECTED AS THE SNOW INTENSIFIES THROUGH THIS MORNING AT MDT...LNS. DUE TO THE MOVEMENT OF THE LOW...THESE SITES WILL REMAIN BELOW VFR FOR THE LONGEST PERIOD DUE TO THIS STORM. EXPECT IFR CIGS AND VSBYS POSSIBLE THROUGH 00Z. IPT AND UNV WILL HAVE MVFR VSYBS TO IFR CIGS POSSIBLE THROUGH THE FIRST HALF OF THE DAY BEFORE IMPROVING INTO THE EARLY EVENING. BFD WILL BE VFR THROUGH MOST OF THE PERIOD...WITH ONLY SOME MVFR CIGS POSSIBLE OVERNIGHT TONIGHT...AS THE FLOW SHIFTS TO THE NORTH. LOW LEVEL WIND- SHEAR WILL ALSO BE POSSIBLE AS LOW LEVEL NORTHEAST FLOW QUICKLY CHANGES AND INCREASES TO EASTERLY JUST OFF THE SURFACE. EXPECT IMPROVING CONDITIONS FOR THU INTO SAT...AS HIGH PRESSURE BUILDS EASTWARD. OUTLOOK... THU...MVFR/IFR -SHSN EARLY...BECOMING VFR. FRI-SUN...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 2 AM EST THURSDAY FOR PAZ057>059. WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ024>026-033>036-063-064. WINTER WEATHER ADVISORY UNTIL 10 PM EST THIS EVENING FOR PAZ027-028-056. WINTER STORM WARNING UNTIL 2 AM EST THURSDAY FOR PAZ065-066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...DANGELO LONG TERM...RXR/TYBURSKI AVIATION...LA CORTE/CERU
AREA FORECAST DISCUSSION
NWS STATE COLLEGE PA
128 AM EST WED MAR 6 2013 .SYNOPSIS... LOW PRESSURE OVER SOUTHERN OHIO WILL WEAKEN AS A SECONDARY LOW DEVELOPS OVER THE SOUTHERN MID-ATLANTIC PIEDMONT EARLY THIS MORNING. THE LOW WILL TRACK SLOWLY NORTHEAST TO THE VIRGINIA TIDEWATER REGION THIS AFTERNOON AND MOVE OFF THE DELMARVA PENINSULA BY THIS EVENING. THIS COMPLEX STORM SYSTEM WILL BRING MODERATE TO HEAVY SNOW TO SOUTH-CENTRAL PENNSYLVANIA. HIGH PRESSURE WILL BUILD IN FROM THE WEST FOR THE WEEKEND WITH FAIR WEATHER AND TEMPERATURES RISING TO NEAR NORMAL. && .NEAR TERM /UNTIL 7 AM THIS MORNING/... RADAR AND SATL LOOP SHOW WELL-DEFINED COMMA HEAD/DEFORMATION PCPN BAND SPREADING NWD INTO SRN PA AS UPPER LOW AND ASSOCD HT FALLS APPROACH THE SPINE OF THE N-CENTRAL APPALACHIANS. 06Z RUC SFC ANALYSIS SHOWS PRIMARY/OCCLUDED LOW OVER SRN OH WITH SECONDARY LOW DEVELOPING OVER THE NC/VA PIEDMONT IN RESPONSE TO 2-4MB 3HR PRES FALLS. AS THE SECONDARY LOW BEGINS TO TRACK SLOWLY TO THE NE EARLY THIS MORNING...EXPECT INCREASING FGEN FORCING TO SUPPORT OCNL 1-1.5 IN/HR SNFL RATES OVR FAR SWRN/S-CENTRAL PA AS THE SNOW BAND CONTINUES TO PUSH NORTH ACRS THE MASON DIXON LINE. ALTHOUGH TEMPS ARE STILL A FEW DEGS ABOVE 32F IN SOME AREAS...EXPECT WET BULB/NOCTURNAL EFFECTS AND ISALLOBARIC FORCING/COLDER NLY FLOW TO RESULT IN ALL SNOW PTYPES. EXTRAPOLATION OF RADAR TRENDS ALONG WITH CONSENSUS OF HI-RES MDLS SHOWS THE NRN EDGE OF THE SNOW CONFINED ALONG AND SOUTH OF IDI-LNS LINE THRU AT LEAST THE NEXT FEW HOURS/09Z WITH A SLIGHT NWD SHIFT LKLY BY 12Z. A VERY SHARP GRADIENT WILL MAKE FOR A DIFFICULT SPATIAL FCST WITH SNOW/NO SNOW OBS OVER A VERY SHORT N-S DISTANCE. EXPECT SEVERAL INCHES OF ACCUM /2-4" IN 6 HRS/ BY DAYBREAK FROM SOMERSET COUNTY EWD TOWARD SOUTH MTN. && .SHORT TERM /7 AM THIS MORNING THROUGH 6 PM THURSDAY/... GUIDANCE CURRENTLY TRENDING A LITTLE FARTHER TO THE SOUTH AND FURTHER DECREASES PRECIP AMOUNTS OVER THE AREA. BUT THIS COULD JUST BE THE LATEST WAGGLE. HOWEVER...WE ARE FULLY INTO THE REALM OF THE SHORT RANGE MODELS AT THIS MOMENT. SO...CONFIDENCE IS HIGH ON THE AMOUNTS FROM A BLEND OF THE NAM/GFS/SREF. HEAVY SNOW MOST LIKELY IN THE LAURELS AND ALONG THE MD BORDER WHERE THE HIGHEST INFLUX OF MSTR FROM THE EAST IS POINTED. THE TREMENDOUS EASTERLY FLOW WILL CREATE A HIGHLY ANOMALOUS 8H POSITIVE MOISTURE FLUX AREA OVER THE SRN COUNTIES DURING THE MORNING AND EARLY AFTN IN OUR SRN COS. THE EXPECTED MESOSCALE HEAVY BANDS OF SNOW WILL BE CAPABLE OF MAKING INCH OR MORE PER HOUR RATES. SO EVEN A SHORTER TIME IN THE FAVORED SNOWFALL PERIOD - NOW MORE LIKE 12-18HRS RATHER THAN A FULL 24 HRS - KEEPS US JUST AS LIKELY TO GET 6 INCHES OR MORE OF ACCUM ACROSS THE SOUTH. THE STORM CENTER WILL BE ALMOST FULLY TRANSITIONED TO THE SECONDARY CENTER AT THE BEGINNING OF THE PERIOD. THE TRACK MADE BY THE STRONG CONSENSUS OF THE DETERMINISTIC MDLS AND ENSEMBLE MEMBERS TAKES IT OUT TO SEA FAR ENOUGH BY WED NIGHT TO DECREASE THE POPS IN THE WEST WED AFTN...AND IN THE EAST AROUND MIDNIGHT. HOWEVER...A POSSIBLE NORTHWARD CURVE TO THE STORM WEDNESDAY EVENING WHEN IT IS WELL OF THE COAST COULD DELAY THE EXIT OF VERY LIGHT PRECIP FROM THE EASTERN COUNTIES UNTIL LATE WED NIGHT. TEMPS ARE AN INTERESTING PART OF THIS FCST - WITH WIDESPREAD 30-33F TEMPS AS THE PRECIP OCCURS. THIS WILL LIKELY CREATE A SOMEWHAT ELEV-DEPENDENT SNOW FALL. LANCASTER CO AND THE LOWER ELEVS OF YORK/DAUPHIN/LEBANON CO WILL BE MOST AT-RISK TO SEE A LITTLE RAIN MIX IN LATE WED/EARLY WED NIGHT. WILL DRAW SNOW ACCUM MAP MORE BROAD- BRUSHED THOUGH FOR SIMPLICITY/S SAKE. THIS ALSO KEEPS A VERY STRONG CONTINUITY IN THE FORECAST SNOW AMOUNTS. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/... LARGE STORM SYSTEM SLIDES OFF EAST COAST BY THURSDAY...WHILE A CHILLY AND RATHER GUSTY NORTHERLY FLOW ARRIVES WITH ISOLATED TO SCATTERED MTN SNOW SHOWERS. AFTER THAT...HEIGHTS BEGIN TO RISE ON FRI...WITH DAYTIME TEMPS MODERATING TO SEASONAL NORMALS THROUGH THE WEEKEND. WARMING TREND CONTINUES INTO EARLY NEXT WEEK...BUT WITH SIGNIFICANT MODEL DIVERGENCE DEVELOPING IN LONGER TERM MODELS. BUT GENERAL PATTERN KEEPS BROAD MILDER WESTERLY FLOW TO EASTERN U.S. WITH A WEAKENING LOW LIFTING ACROSS THE NORTHEAST MON NIGHT INTO TUE INCREASING CHANCES FOR PRIMARILY RAIN SHOWERS. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... UPCOMING STORM STILL ON TRACK TO HAVE THE HIGHEST IMPACT ALONG THE SOUTHERN TIER OF THE FCST AREA...WITH IMPACTS DECREASING OVER CENTRAL AND NORTHERN PA. SNOW IS INVADING SWRN AREAS AS OF 11 PM...AND WILL SPREAD EASTWARD FOR THE REMAINDER OF THE OVERNIGHT. AS THE LOW MOVES OFF TO OUR SOUTH AND INTENSIFIES LATE TONIGHT AND EARLY WEDNESDAY...SNOW WILL INCREASE IN INTENSITY WITH RAPID DETERIORATION TO IFR/LIFR VISIBILITIES TO BE EXPECTED. BEST CHANCE OF IFR/LIFR WILL BE FROM JST EAST TO MDT/LNS. LOW LEVEL WIND-SHEAR WILL ALSO BE POSSIBLE AS LOW LEVEL NORTHEAST FLOW QUICKLY CHANGES AND INCREASES TO EASTERLY JUST OFF THE SURFACE. ACROSS CENTRAL AND NORTHERN PENNSYLVANIA...SNOWFALL AND FLIGHT CONDITIONS WILL BE LESS AFFECTED. MVFR TO OCCASIONAL IFR AT KUNV POSSIBLY UP TO KIPT. KBFD WILL BE THE LEAST AFFECTED WITH VFR TO OCCASIONAL MVFR AT TIMES IN MAINLY FLURRIES. EXPECT IMPROVING CONDITIONS FOR THU INTO SAT...AS HIGH PRESSURE BUILDS EASTWARD. OUTLOOK... THU...MVFR/IFR -SHSN EARLY...BECOMING VFR. FRI-SUN...NO SIG WX. && .CTP WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 2 AM EST THURSDAY FOR PAZ027-028- 056>059. WINTER STORM WARNING UNTIL 10 PM EST THIS EVENING FOR PAZ024>026-033>036-063-064. WINTER STORM WARNING UNTIL 2 AM EST THURSDAY FOR PAZ065-066. && $$ SYNOPSIS...STEINBUGL NEAR TERM...STEINBUGL SHORT TERM...DANGELO LONG TERM...RXR/TYBURSKI AVIATION...LA CORTE
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1037 PM EST THU MAR 7 2013 .SYNOPSIS... COOL AND DRY CANADIAN HIGH PRESSURE WILL REMAIN OVER THE REGION INTO THE WEEKEND. A COLD FRONT WILL MOVE ACROSS THE REGION LATE MONDAY REACHING THE COAST BY TUESDAY. ANOTHER DRY HIGH WILL MOVE INTO THE AREA FOR MID WEEK. && .NEAR TERM /THROUGH FRIDAY/... AS OF 1035 PM EST THU...BLENDED IN SOME RUC13 WINDS WHICH HAS BUMPED UP THE SPEEDS A LITTLE OVER THE NRN PART OF THE UPSTATE AND THE SRN NC PIEDMONT. WINDS ARE RUNNING AROUND 10 KTS IN THESE AREAS ATTM. OTHERWISE THE SKY GRIDS WERE AGAIN TWEAKED TO CAPTURE THE CURRENT ORIENTATION OF THE STRATO-CU ALONG THE TN LINE. IT/S MADE SOME PROGRESS UP THE FRENCH BROAD AND PIGEON RIVER VALLEYS...THOUGH I DON/T SEE IT GETTING MUCH FURTHER SOUTH. TEMPERATURES WERE LOWERED AGAIN OVER THE NRN NC FOOTHILLS. AS OF 755 PM EST THU...ADDED A LITTLE MORE CLOUD COVER RIGHT ALONG THE TN LINE. ALSO LOWERED HOURLY TEMPS A FEW DEGREES OVER THE NRN MTNS AND NC FOOTHILLS WHERE TEMPS ARE RUNNING LOWER THAN PREDICTED. THE REST OF THE GRIDS LOOK TO BE IN GOOD SHAPE. AS OF 510 PM EST THU...UPDATED SKY GRIDS TO ACCOUNT FOR SHARP CLEARING LINE ALONG THE TN LINE. UPSTREAM STRATUS HAS BEEN VERY PERSISTENT AND I HAVE IT HOLDING ON RIGHT ALONG THE LINE FOR SEVERAL MORE HOURS. THE OTHER 98 PERCENT OF THE FORECAST AREA WILL HAVE A LOVELY EVENING. TEMPERATURES WERE ALSO ADJUSTED DOWN A FEW DEGREES OVER THE CENTRAL AND NRN MTNS...MAINLY AS A RESULT OF SNOW COVER. PREVIOUS DISCUSSION... THE REGION WILL REMAIN UPSTREAM OF A LONG WAVE TROUGH OFF THE EAST COAST...WITH HIGH AMPLITUDE RIDGING TO THE WEST THROUGH THE PERIOD. THIS WILL SUPPORT A RIDGE OF SURFACE HIGH PRESSURE ACROSS THE REGION. SOME DEGREE OF LOW LEVEL MOISTURE WILL CONTINUE TO SUPPORT UPSLOPE STRATOCU ALONG THE IMMEDIATE TENN BORDER...AND THIS MAY EVEN EXPAND A BIT TONIGHT. OTHER THAN THAT...FAIRLY GOOD RADIATIONAL COOLING CONDITIONS ARE EXPECTED TONIGHT...WHICH SHOULD ALLOW MIN TEMPS TO COOL TO ABOUT 10 DEGREES BELOW NORMAL. FRIDAY...THE WESTERN ATLANTIC TROUGH RECEIVES SOME REINFORCEMENT... AS A POTENT SHORT WAVE DIGS OFF THE MID-ATLANTIC COAST. THIS WILL SUPPORT CONTINUED LOW THICKNESS VALUES ACROSS OUR AREA...AND MAX TEMPS WILL BE ONLY MARGINALLY DIFFERENT THAN TODAY/S READINGS. && .SHORT TERM /FRIDAY NIGHT THROUGH SUNDAY/... AS OF 145 PM THURSDAY...AN UPPER LEVEL RIDGE WILL DOMINATE THE WEATHER THROUGH THE UPCOMING WEEKEND PROVIDING VERY PLEASANT AND DRY WEATHER. THE RIDGE AXIS IS FORECAST TO MOVE EAST OF THE APPALACHIANS BY 12Z SUNDAY. AT THE SFC...A NORTH TO SOUTH ORIENTED HIGH PRESSURE SYSTEM WILL MOVE FROM THE MID WEST FRIDAY NIGHT...TO OFF THE EAST COAST ON SUNDAY. THIS WILL RESULT IN MOSTLY CLEAR CONDITIONS THROUGH SAT NIGHT. THE RETURN FLOW ON THE WESTERN PERIPHERY OF THE HIGH WILL TRANSPORT INCREASING ATLANTIC MOISTURE INTO THE AREA BEGINNING SAT NIGHT AND CONTINUING ON SUN. THEREFORE...EXPECT INCREASING AMOUNTS OF CLOUDS FROM LATE SATURDAY NIGHT INTO SUNDAY. RIDGING ALOFT AND WARMING LOW LEVEL THICKNESSES SHOULD RESULT IN ABOVE NORMAL HIGHS BOTH SATURDAY AND SUNDAY. MAX TEMPS SHOULD REACH THE MID 60S OUTSIDE THE MOUTNAINS...WITH EVEN LOW 60S MOUNTAIN VALLEYS. GOOD RADIATIONAL COOLING FRI NIGHT WILL ALLOW MIN TEMPS TO COOL AROUND 5 DEGREES BELOW NORMAL...BUT NEAR TO A LITTLE ABOVE NORMAL TEMPS SHOULD OCCUR SAT NIGHT AS MOISTURE INCREASES. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 145 PM EST THURSDAY...07/12Z GFS AND 07/00Z ECM ARE IN FAIRLY GOOD AGREEMENT IN REGARD TO THE PERTINENT WEATHER FEATURES THROUGH THE MEDIUM RANGE. THE 07/12Z CANADIAN CAME IN AS AN OUTLIER AND WAS DISREGARDED FOR THIS FORECAST. AN UPPER RIDGE WILL BE MOVING EAST OF THE AREA AT THE BEGINNING OF THE PERIOD WITH A SHORT WAVE TROUGH OVER THE MIDWEST. THE UPPER TROUGH IS FORECAST TO MOVE EAST AND TRAVERSE THE REGION MONDAY NIGHT INTO TUE. THE TROUGH WILL DRIVE A SURFACE COLD FRONT THROUGH THE AREA. MODEL TIMING FOR THE COLD FRONTAL PASSAGE IS CONVERGING ON MON NIGHT INTO EARLY TUE. AS SURFACE HIGH PRESSURE MOVES EAST OF THE AREA SUNDAY NIGHT AND MON...THE RETURN FLOW WILL TAP INTO ATLANTIC/GULF MOISTURE OUT AHEAD OF THE COLD FRONT. A FEW SHOWERS COULD DEVELOP OVER WESTERN UPSLOPE AREAS BY EARLY MON. SHOWERS ARE THEN EXPECTED TO SLOWLY EVERSPREAD MOST OF THE AREA ON MONDAY FROM WEST TO EAST. THE COLD FRONT WILL CROSS THE AREA MONDAY NIGHT INTO EARLY TUE. MODERATE AMOUNTS OF RAINFALL ARE EXPECTED ACROSS THE REGION...MOST LIKELY IN THE HALF INCH TO INCH RANGE. WITH THE FRONTAL PASSAGE OCCURRING DURING THE NIGHT...INSTABILITY WILL BE LIMITED SO DO NOT HAVE ANY THUNDER MENTIONED. ALSO...TEMPERATURES SHOULD BE MILD ENOUGH SO THAT NO PTYPE ISSUES AREA EXPECTED. THE ONLY EXECEPTION MAY THE ELEVATIONS ABOVE 3500FT IN THE WAKE OF THE FRONT WHERE THERE COULD BE A BRIEF PERIOD OF SNOW MIXED WITH RAIN. BEHIND THE FRONT...DRYING NW FLOW SHOULD COMMENCE SO CLEARING SHOULD OCCUR WEST TO EAST ACROSS THE AREA ON TUE. HIGH PRESSURE WILL BUILD TOWARD THE AREA ON WED/THU. 12Z GFS TIME/HEIGHTS SUGGEST LOW LEVEL MOISTURE MAY BE SUFFICENT FOR MORE CLOUDS ON WED/THU BUT WILL STAY CLOSER TO THE DRYER ECM SOLUTION AND FORECAST MOSTLY CLEAR/CLEAR SKY CONDITIONS. TEMPS WILL BEGIN THE PERIOD A LITTLE ABOVE AVERAGE AND THEN COOL SLIGHTLY BELOW NORMAL BY THE END OF THE PERIOD. && .AVIATION /04Z FRIDAY THROUGH TUESDAY/... AT KCLT AND ELSEWHERE...CLEAR SKIES THROUGH THE PERIOD. WINDS WILL GENERALLY BE OUT OF THE NORTH AT 6 TO 8 KTS OVERNIGHT. THE DIRECTION WILL REMAIN THE SAME ON FRIDAY...THOUGH SOME GUSTS COULD DEVELOP BY LATE MORNING...ESPECIALLY AT KCLT. I DIDN/T ADD GUSTS TO THIS TAF PACKAGE...BUT IF THE MOMENTUM XFER LOOKS BETTER ON LATER MODEL RUNS...THE MID SHIFT MAY NEED TO DO IT. AT KAVL...GUSTY NW WINDS WILL PERSIST THROUGH AROUND 0300 UTC. AFTER THAT TIME THE GRADIENT SHOULD SLACKEN ENOUGH FOR THE GUSTS TO STOP AN FOR THE SUSTAINED WINDS TO FALL UNDER 10 KTS. OUTLOOK...DRY HIGH PRESSURE WILL PERSIST THROUGH THE WEEKEND. MOISTURE AND RESTRICTIONS SHOULD RETURN BY LATE MONDAY AHEAD OF THE NEXT APPROACHING COLD FRONT. CONFIDENCE TABLE... 03-09Z 09-15Z 15-21Z 21-03Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL HIGH 100% HIGH 100% HIGH 100% HIGH 100% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...JDL/MCAVOY SHORT TERM...LG LONG TERM...LG AVIATION...MCAVOY
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
830 PM CST THU MAR 7 2013 .DISCUSSION.../ISSUED 830 PM CDT/ FORECAST PACKAGE LOOKS ON TRACK FOR THE SHORT TERM WITH ONLY COSMETIC UPDATES MADE. TEMPERATURES ARE COOLING A BIT SLOWER THAN FORECAST THIS EVENING WITH CIRRUS STREAM OVERHEAD AND SOUTHEAST FLOW IN PLACE. STILL A TRICKY FORECAST REGARDING STRATUS DEVELOPMENT LATE TONIGHT BUT CURRENT THINKING IS LOW STRATUS OVER NORTH DAKOTA WILL EXPAND SOUTH AND PERHAPS ENTER THE NORTH-WESTERN FRINGE COUNTIES ALONG AND NORTH OF SURFACE TROUGH LATE TONIGHT. THEN AS THE NEXT SYSTEM APPROACHES TOMORROW...LOW CLOUDS WILL ADVECT NORTHWARD WITH INCREASING SOUTHERLY FLOW AND MID-LVL CLOUDS WILL INCREASE FROM THE SOUTH. /AEB .PREVIOUS DISCUSSION.../ISSUED AT 333 PM CDT/ FAIRLY QUIET NIGHT AHEAD AS CIRRUS STREAM OVERHEAD AND A SOUTHEAST GRADUALLY DECREASE THROUGH THE NIGHT. THE MAIN CHALLENGE WILL BE STRATUS REDEVELOPMENT...MAINLY WHAT TIME. MODELS HAVE NOT BEEN HANDLING THE LOW LEVEL MOISTURE ALL THAT WELL AS OF LATE AND TONIGHT LIKELY TO BE NO DIFFERENT. FOR NOW WILL PLAN ON ADDING SOME REDEVELOPMENT AROUND NORTHWEST IOWA AFTER 6Z AND THEN SPREADING NORTHWEST THE REMAINDER OF THE NIGHT. THIS SHOULD LEAD TOWARDS A MOSTLY CLOUDY DAY ON FRIDAY AS WE AWAIT THE WEEKEND WINTER WEATHER SYSTEM. LOWS TONIGHT WILL BE MILD WITH CLOUDS AND SOUTH WINDS BUT A FEW LOCATIONS COULD SEE WINDS DROP OFF SO WHILE LOWS WILL MAINLY BE IN THE 20S A FEW TEENS WILL BE POSSIBLE IN AREAS WITH THINNER CLOUD COVER AND LIGHT WINDS...LIKELY ALONG HIGHWAY 14. FRIDAY HIGHS WILL WARM NICELY WITH IN THE SOUTH BUT NOT QUITE AS MUCH IN THE NORTH. HIGHS SHOULD RANGE FROM THE MID 30S NORTH TO THE MID 40S SOUTH. UPPER LEVEL SUPPORT AND DEEPER MOISTURE SPREAD NORTH DURING THE DAY AND COULD SEE THE POTENTIAL FOR SOME SHOWERS TO DEVELOP AFTER ABOUT 21Z. /08 CONTINUE TO SEE THE POTENTIAL FOR PRECIPITATION FROM THIS SYSTEM TO KICK OFF WITH A LITERAL BANG FRIDAY EVENING. RAPIDLY INCREASING THERMAL GRADIENT AND INCREASING INSTABILITY FROM THE SOUTH SHOULD RESULT IN DEVELOPING CONVECTION...INCLUDING A FEW THUNDERSTORMS...TO AFFECT THE SOUTHEASTERN PART OF THE AREA. THIS CONVECTION SHOULD SPREAD NORTH/NORTH NORTHEAST FRIDAY NIGHT. THE SHARPENING THERMAL GRADIENT AND DEVELOPMENT OF THE INVERTED TROUGH INTO THE AREA SHOULD EVENTUALLY SPAWN WEAKER CONVECTION OVER THE WESTERN PART OF THE AREA. WITH TEMPERATURES ALOFT TOO WARM FOR SNOW FRIDAY NIGHT...THE WINTER WEATHER THREAT WILL OF COURSE DEPEND ON SURFACE TEMPERATURES. THE GREATEST THREAT FOR FREEZING RAIN SEEMS OVER THE NORTH CENTRAL EDGE OF THE AREA...PERHAPS CENTERED ON BROOKINGS...WHICH THREAT WILL CONTINUE INTO SATURDAY MORNING. THE THREAT MAY EXTEND TO HURON ON THE WEST AND TO MARSHALL MN TO THE EAST...THOUGH MARSHALL MAY BE ON THE FRINGE OF ENOUGH SURFACE WARMING ALONG/EAST OF TROUGH TO SOMEWHAT MITIGATE ICING. AFTER SATURDAY MORNING THE EVOLUTION OF THE SYSTEM AND WINTER WEATHER THREAT WILL DEPEND ON HOW WELL MODELS ARE HANDLING THE SYSTEM. AS WE HAVE GOTTEN CLOSER...THE GFS AND EC HAVE REVERSED THEIR PATTERNS. THE GFS WHICH WAS SHEARING THE SYSTEM SOUTH WITH THE NORTHERN STREAM SHORT WAVE NOW GIVES OUR AREA A DECENT EVENT...AND PERHAPS A POTENTIAL OF A DECENT SNOW ACCUMULATION BAND OVER PART OF OUR SOUTHEAST INCLUDING FSD. THE NAM IS THE SAME WAY THOUGH QUITE A BIT FASTER THAN THE GFS. THE EC HOWEVER IS THE ONE SUPPRESSING THE MAIN SYSTEM NOW. AT THIS TIME OF YEAR WILL GO WITH THE GFS/NAM WITH A COMPROMISE ON SPEED. POTENTIAL SNOW AND ICE ACCUMULATIONS SEEM SIGNIFICANT BUT TOO LOW FOR WINTER STORM CONDITIONS AT THIS TIME SO NO WATCH. THE PRECIPITATION SHOULD SLOWLY BEGIN TO CHANGE TO SNOW FROM THE NORTHWEST BY LATE SATURDAY MORNING...THEN THE CHANGEOVER SHOULD PROGRESS MORE RAPIDLY LATE SATURDAY AND SATURDAY EVENING AS THE MAIN SYSTEM APPROACHES. SNOW SHOULD THEN DECREASE FROM THE NORTHWEST SATURDAY NIGHT AND SUNDAY MORNING. WINDS WILL PICK UP SOME BUT NO GALE...AND WITH LIMITED SNOW AMOUNTS EXPECTED...WILL NOT ADD BLOWING SNOW AT THIS TIME. TEMPERATURES OF COURSE WILL COOL SATURDAY NIGHT AND SPEND SUNDAY BELOW FREEZING EVERYWHERE. MONDAY THROUGH THURSDAY LOOKS DRY AND TURNING MILDER...HAVE DAMPENED THE EXPECTED WARMING SLIGHTLY BY FROM GUIDANCE THURSDAY AS THE DAY MODELS ARE SHOWING A MINOR COOL INTRUSION FOR WEDNESDAY BEHIND A WEAK SYSTEM MOVING EAST NEAR THE CANADIAN BORDER. RIDGING AND PERHAPS SPRINGLIKE WARMING LOOK LIKE A BETTER BET JUST AFTER THIS FORECAST PERIOD...PERHAPS TARGETING THE ST. PATRICKS DAY WEEKEND. IN ANY EVENT...UPPER SUPPORT AND MOISTURE SEEM TOO MEAGER OR NONEXISTENT FOR ANY PRECIPITATION FOR A WHILE AFTER THIS CURRENT SYSTEM MOVES OUT SUNDAY. && .AVIATION.../FOR THE 00Z TAF ISSUANCE/ HAVE SIDED WITH MAINLY VFR FORECAST THROUGH 00Z SATURDAY FOR TAF SITES. EXCEPTION TO THIS IS AT KHON WHERE THERE MAY BE A FEW HOURS OF IFR STRATUS NEAR SUNRISE. HRRR SOUNDINGS ARE NOT NEAR AS MOIST IN THE NEAR SURFACE LAYER AS THE NAM OR GFS WOULD SUGGEST...AND THEREFORE REMOVED STRATUS POTENTIAL FOR KFSD AND KSUX. FAIRLY DENSE SHIELD OF HIGH CLOUDS ACROSS THE AREA WILL ALSO LIMIT RADIATIVE COOLING SOME LIMITING THE POTENTIAL FOR LOW CLOUD DEVELOPMENT. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
540 PM CST THU MAR 7 2013 .DISCUSSION.../ISSUED AT 333 PM CDT/ FAIRLY QUIET NIGHT AHEAD AS CIRRUS STREAM OVERHEAD AND A SOUTHEAST GRADUALLY DECREASE THROUGH THE NIGHT. THE MAIN CHALLENGE WILL BE STRATUS REDEVELOPMENT...MAINLY WHAT TIME. MODELS HAVE NOT BEEN HANDLING THE LOW LEVEL MOISTURE ALL THAT WELL AS OF LATE AND TONIGHT LIKELY TO BE NO DIFFERENT. FOR NOW WILL PLAN ON ADDING SOME REDEVELOPMENT AROUND NORTHWEST IOWA AFTER 6Z AND THEN SPREADING NORTHWEST THE REMAINDER OF THE NIGHT. THIS SHOULD LEAD TOWARDS A MOSTLY CLOUDY DAY ON FRIDAY AS WE AWAIT THE WEEKEND WINTER WEATHER SYSTEM. LOWS TONIGHT WILL BE MILD WITH CLOUDS AND SOUTH WINDS BUT A FEW LOCATIONS COULD SEE WINDS DROP OFF SO WHILE LOWS WILL MAINLY BE IN THE 20S A FEW TEENS WILL BE POSSIBLE IN AREAS WITH THINNER CLOUD COVER AND LIGHT WINDS...LIKELY ALONG HIGHWAY 14. FRIDAY HIGHS WILL WARM NICELY WITH IN THE SOUTH BUT NOT QUITE AS MUCH IN THE NORTH. HIGHS SHOULD RANGE FROM THE MID 30S NORTH TO THE MID 40S SOUTH. UPPER LEVEL SUPPORT AND DEEPER MOISTURE SPREAD NORTH DURING THE DAY AND COULD SEE THE POTENTIAL FOR SOME SHOWERS TO DEVELOP AFTER ABOUT 21Z. /08 CONTINUE TO SEE THE POTENTIAL FOR PRECIPITATION FROM THIS SYSTEM TO KICK OFF WITH A LITERAL BANG FRIDAY EVENING. RAPIDLY INCREASING THERMAL GRADIENT AND INCREASING INSTABILITY FROM THE SOUTH SHOULD RESULT IN DEVELOPING CONVECTION...INCLUDING A FEW THUNDERSTORMS...TO AFFECT THE SOUTHEASTERN PART OF THE AREA. THIS CONVECTION SHOULD SPREAD NORTH/NORTH NORTHEAST FRIDAY NIGHT. THE SHARPENING THERMAL GRADIENT AND DEVELOPMENT OF THE INVERTED TROUGH INTO THE AREA SHOULD EVENTUALLY SPAWN WEAKER CONVECTION OVER THE WESTERN PART OF THE AREA. WITH TEMPERATURES ALOFT TOO WARM FOR SNOW FRIDAY NIGHT...THE WINTER WEATHER THREAT WILL OF COURSE DEPEND ON SURFACE TEMPERATURES. THE GREATEST THREAT FOR FREEZING RAIN SEEMS OVER THE NORTH CENTRAL EDGE OF THE AREA...PERHAPS CENTERED ON BROOKINGS...WHICH THREAT WILL CONTINUE INTO SATURDAY MORNING. THE THREAT MAY EXTEND TO HURON ON THE WEST AND TO MARSHALL MN TO THE EAST...THOUGH MARSHALL MAY BE ON THE FRINGE OF ENOUGH SURFACE WARMING ALONG/EAST OF TROUGH TO SOMEWHAT MITIGATE ICING. AFTER SATURDAY MORNING THE EVOLUTION OF THE SYSTEM AND WINTER WEATHER THREAT WILL DEPEND ON HOW WELL MODELS ARE HANDLING THE SYSTEM. AS WE HAVE GOTTEN CLOSER...THE GFS AND EC HAVE REVERSED THEIR PATTERNS. THE GFS WHICH WAS SHEARING THE SYSTEM SOUTH WITH THE NORTHERN STREAM SHORT WAVE NOW GIVES OUR AREA A DECENT EVENT...AND PERHAPS A POTENTIAL OF A DECENT SNOW ACCUMULATION BAND OVER PART OF OUR SOUTHEAST INCLUDING FSD. THE NAM IS THE SAME WAY THOUGH QUITE A BIT FASTER THAN THE GFS. THE EC HOWEVER IS THE ONE SUPPRESSING THE MAIN SYSTEM NOW. AT THIS TIME OF YEAR WILL GO WITH THE GFS/NAM WITH A COMPROMISE ON SPEED. POTENTIAL SNOW AND ICE ACCUMULATIONS SEEM SIGNIFICANT BUT TOO LOW FOR WINTER STORM CONDITIONS AT THIS TIME SO NO WATCH. THE PRECIPITATION SHOULD SLOWLY BEGIN TO CHANGE TO SNOW FROM THE NORTHWEST BY LATE SATURDAY MORNING...THEN THE CHANGEOVER SHOULD PROGRESS MORE RAPIDLY LATE SATURDAY AND SATURDAY EVENING AS THE MAIN SYSTEM APPROACHES. SNOW SHOULD THEN DECREASE FROM THE NORTHWEST SATURDAY NIGHT AND SUNDAY MORNING. WINDS WILL PICK UP SOME BUT NO GALE...AND WITH LIMITED SNOW AMOUNTS EXPECTED...WILL NOT ADD BLOWING SNOW AT THIS TIME. TEMPERATURES OF COURSE WILL COOL SATURDAY NIGHT AND SPEND SUNDAY BELOW FREEZING EVERYWHERE. MONDAY THROUGH THURSDAY LOOKS DRY AND TURNING MILDER...HAVE DAMPENED THE EXPECTED WARMING SLIGHTLY BY FROM GUIDANCE THURSDAY AS THE DAY MODELS ARE SHOWING A MINOR COOL INTRUSION FOR WEDNESDAY BEHIND A WEAK SYSTEM MOVING EAST NEAR THE CANADIAN BORDER. RIDGING AND PERHAPS SPRINGLIKE WARMING LOOK LIKE A BETTER BET JUST AFTER THIS FORECAST PERIOD...PERHAPS TARGETING THE ST. PATRICKS DAY WEEKEND. IN ANY EVENT...UPPER SUPPORT AND MOISTURE SEEM TOO MEAGER OR NONEXISTENT FOR ANY PRECIPITATION FOR A WHILE AFTER THIS CURRENT SYSTEM MOVES OUT SUNDAY. && .AVIATION.../FOR THE 00Z TAF ISSUANCE/ HAVE SIDED WITH MAINLY VFR FORECAST THROUGH 00Z SATURDAY FOR TAF SITES. EXCEPTION TO THIS IS AT KHON WHERE THERE MAY BE A FEW HOURS OF IFR STRATUS NEAR SUNRISE. HRRR SOUNDINGS ARE NOT NEAR AS MOIST IN THE NEAR SURFACE LAYER AS THE NAM OR GFS WOULD SUGGEST...AND THEREFORE REMOVED STRATUS POTENTIAL FOR KFSD AND KSUX. FAIRLY DENSE SHIELD OF HIGH CLOUDS ACROSS THE AREA WILL ALSO LIMIT RADIATIVE COOLING SOME LIMITING THE POTENTIAL FOR LOW CLOUD DEVELOPMENT. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
350 PM CST WED MAR 6 2013 .DISCUSSION.../ISSUED AT 350 PM CST/ CHALLENGES TONIGHT AND TOMORROW FOCUS ON STRATUS...OR POSSIBLY A LACK THERE OF. THIS IS NOT AN EASY ONE TO ANSWER TONIGHT AS THE STRATUS IS QUICKLY ERODING FROM THE SOUTHWEST TODAY AND WITH AN INCREASED SOUTHERLY GRADIENT OVERNIGHT INDICATIONS ARE THAT IT MAY REMAIN AT BAY IN LOCATIONS WHERE IT ERODES. HOWEVER...IF SOME OF THESE BETTER WINDS ALOFT DO NOT MIX DOWN AN ALREADY STRONG INVERSION MAY GET A LITTLE STRONGER THROUGH THE NIGHT ALLOWING STRATUS TO REDEVELOP FROM THE EAST AND SOUTHEAST. SO REALLY COULD SEE EITHER SOLUTION OCCURRING. SO...BECAUSE OF A LACK OF CONFIDENCE WILL NOT CHANGE LOWS MUCH BUT IF THE FAR EASTERN CWA REMAINS CLOUDY ALL NIGHT THE LOWS WILL PROBABLY BE A LITTLE WARMER THAN FORECAST. A BIT BREEZY ON THURSDAY AS THE WINDS PICK UP FROM THE SOUTHEAST. WILL KEEP TEMPERATURES IN THE LOWER TO MIDDLE 30S OVER EXISTING SNOW COVER WHILE AREAS WITH NO SNOW IN SOUTH CENTRAL SOUTH DAKOTA SHOULD EASILY REACH THE MID 40S. /08 THURSDAY NIGHT AND FRIDAY SHOULD BE RELATIVELY MILD WITH MOST OF THE CLOUD INCREASE AHEAD OF APPROACHING SYSTEM COMING VERY LATE THURSDAY NIGHT AND FRIDAY. AT THIS TIME DO NOT SEE PRECIPITATION DEVELOPING UNTIL EARLY FRIDAY EVENING...BUT IT COULD DEVELOP RAPIDLY AT THAT TIME. THE PRESENCE OF A STRENGTHENING FRONTAL BOUNDARY... MOISTURE ADVECTION...AND DESTABILIZATION IS EXPECTED TO BRING SHOWERY RAINS AND MAYBE EVEN THUNDERSTORMS SOUTHEAST...WITH LESS CONVECTIVE BUT STILL VARIABLY INTENSITY PRECIPITATION NORTHWEST. WARMING AHEAD OF THIS SYSTEM SHOULD PRECLUDE SNOW EVEN NORTHWEST...BUT LOW LEVEL COOLING SEEMS LIKELY NORTH AND NORTHWEST OF THE FRONT AS IT QUICKLY STRENGTHENS...AND THIS ADDS UP TO A SIGNIFICANT FREEZING RAIN THREAT NORTH AND WEST. THIS THREAT SHOULD CONTINUE SATURDAY AND BEGIN SHIFTING SOUTHEAST...WHILE SNOW DEVELOPS GRADUALLY FROM THE NORTHWEST AS DYNAMIC AND EVAPORATIONAL COOLING GAIN SWAY WITH THE APPROACH OF UPPER LOW FROM THE SOUTHWEST AND NORTHERN STREAM UPPER TROUGH. SOME PRECIPITATION...MAINLY SNOW...SHOULD CONTINUE INTO SUNDAY. AT THIS TIME THE FREEZING RAIN SEEMS LIKE THE MAIN WINTER WEATHER THREAT AS THE UPPER LOW WILL START TO BE DRIVEN MORE EAST NORTHEAST WITH TIME. THIS MEANS MOST OF THE PRECIPITATION WILL OCCUR EARLY IN THE EVENT FROM THE GREATLY SHARPENING THERMAL GRADIENT AND INSTABILITY. THE MORE DYNAMICALLY RELATED PRECIPITATION LATER ON...AFTER UPPER COOLING...MAY NOT BE TOO GREAT WITH THIS DIVERTING OF THE UPPER LOW. DESPITE DIFFERENCES FROM YESTERDAYS RUNS...YESTERDAYS ACTION OF CUTTING OFF THE PRECIPITATION FROM EARLY NEXT WEEK LOOKS TO BE TURNING OUT VERY WELL. MONDAY THROUGH WEDNESDAY SHOULD BE DRY AND WITHIN SHOUTING DISTANCE OF SEASONABLE...A BIT BELOW IT AT THE START...AS THE UPPER RIDGING MOVES IN FROM THE WEST. THE KIND OF COLD OUTLOOK FOR THE LONG RANGE AFTER OUR FORECAST PERIOD FROM EARLIER IN THE WEEK SEEMS TO BE TURNING MILDER. && .AVIATION.../FOR THE 18Z TAF ISSUANCE/ QUICKLY LOOPING THROUGH THE VISIBLE SATELLITE SHOWS THAT THE EXISTING STRATUS IS PRETTY THIN AND AT THIS TIME FAIRLY QUICKLY ERODING FROM THE SOUTHWEST. THE RAP HAS US MIRED IN THE GUNK THROUGH LATE TONIGHT WHILE THE OTHER MODELS TEMPORARILY BREAK US OUT OF THE LOW END MVFR CEILINGS...THEN SUGGEST REDEVELOPMENT LATER TONIGHT. NO EASY ANSWER HERE AS SOME QUESTION THAT IF STRATUS IS ABLE TO DISSIPATE THIS AFTERNOON AN INCREASING SOUTHERLY GRADIENT MAY MAKE IT DIFFICULT TO REDEVELOP. HOWEVER...WILL LEAN TOWARDS THE MORE PESSIMISTIC SOLUTION AND PLAN ON THE STRATUS REDEVELOPING UNDER A FAIRLY STRONG INVERSION AND THINKING MVFR TO IFR CEILINGS OVERNIGHT MOST LOCATIONS. /08 && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
130 PM CST WED MAR 6 2013 .DISCUSSION.../ISSUED AT 445 AM CST/ LOOKS LIKE A QUIET COUPLE OF DAYS ACROSS THE REGION...BUT THAT DOES NOT MEAN THE FORECAST IS WITHOUT ITS CHALLENGES. OF PRIMARY CONCERN TODAY IS WIDESPREAD STRATUS WHICH IS NOW STUCK UNDER SURFACE RIDGE ADVANCING SLOWLY EASTWARD TODAY. OTHER THAN HIGH-RESOLUTION SHORT RANGE MODELS...WHICH SEEM TO HAVE BETTER GRASP ON CURRENT REALITY... HAVE LITTLE USEFUL GUIDANCE TO FOLLOW REGARDING PERSISTENCE OF THE LOW LEVEL MOISTURE. THUS FOLLOWED MORE PESSIMISTIC RAP/HRRR VIEW... HOLDING ONTO EXTENSIVE CLOUD COVER MUCH OF THE DAY WITH POSSIBILITY OF SOME HOLES DEVELOPING IN THE LATE AFTERNOON AS MARCH SUN HAS A CHANCE TO ERODE AROUND ANY BREAKS WHICH MAY DEVELOP. GREATER CLOUD COVER WILL LEAD TO COOLER TEMPS...THOUGH PREVIOUS FORECAST ALREADY ON THE COOL SIDE WITH LIGHT FLOW ACROSS THE EAST SO DID NOT LOWER HIGHS TOO MUCH AT THIS POINT. FOR TONIGHT...NAM LOW LEVEL MOISTURE HINTS AT POTENTIAL FOR STRATUS TO REDEVELOP ACROSS CENTRAL SD AS RETURN SOUTHERLY FLOW DRAWS DEEPER MOISTURE NORTHWARD BEHIND THE DEPARTING RIDGE. IF THIS DOES DEVELOP IT COULD LINGER INTO AT LEAST MIDDAY THURSDAY...AGAIN IMPACTING HIGH TEMPERATURES AND COOLED HIGHS IN THE WEST BY A FEW DEGREES...THOUGH WITH 925MB TEMPERATURES ANYWHERE FROM 4-6C...COULD STILL MIX INTO THE MID TO UPPER 40S WEST OF THE JAMES RIVER. ATTENTION THEN TURNS TO WEEKEND SYSTEM...WHICH MODELS HAVE COME INTO SLIGHTLY BETTER AGREEMENT ON WHEN COMPARED TO PAST COUPLE OF NIGHTS. FAVORED SOLUTION DEPICTS STRONGER BUT PROGRESSIVE NORTHERN STREAM TROUGH MOVING EAST ACROSS NORTH DAKOTA/MINNESOTA SATURDAY/SATURDAY NIGHT...WHICH DOES NOT ALLOW SOUTHERN STREAM CUTOFF LOW TO SWING NORTH AND STRENGTHEN AS HAS BEEN SEEN IN PREVIOUS ECMWF RUNS. THIS SOLUTION DOES GIVE THIS AREA A GOOD CHANCE OF SOME DECENT PRECIP... WITH GOOD CONSENSUS POINTING TO LATE FRIDAY NIGHT THROUGH SATURDAY NIGHT AS PERIODS WITH GREATEST POTENTIAL. COULD SEE SOME LIGHT PRECIP BREAK OUT ACROSS THE WEST ALREADY BY FRIDAY AFTERNOON...AS BROAD WARM ADVECTION BEGINS TO KICK IN. THIS BROAD LIFT ACROSS INVERTED TROUGH REMAINS PERSISTENT INTO FRIDAY NIGHT...WITH GROWING CONFIDENCE FOR BUMPING POPS INTO LIKELY RANGE ACROSS MUCH OF THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL CARRY LIKELY POPS INTO SATURDAY NIGHT OVER THE SOUTHEAST HALF OF THE CWA AS BOUNDARY IS PULLED EAST OF THE AREA BY DEPARTING NORTHERN STREAM WAVE. WHILE CONFIDENCE IN PRECIPITATION CHANCE IS GROWING...PRECIPITATION TYPE BECOMES A HUGE QUESTION MARK. GFS/ECMWF BOTH PUMP WARM AIR WELL NORTH ACROSS THE REGION...WITH FREEZING LINE NEAR ND/SD BORDER AT 850MB...AND NEAR THE NORTHERN EDGE OF OUR FORECAST AREA AT 925MB BY FRIDAY EVENING. CONTINUED SOUTHERLY FLOW ACROSS THE AREA FRIDAY NIGHT KEEPS THE WARM LAYER LOCKED IN PLACE AT LEAST INTO SATURDAY MORNING...WITH COOLING ONLY TAKING PLACE IN THE WEST BY SATURDAY AFTERNOON/EVENING AS INVERTED TROUGH BEGINS TO ADVANCE EASTWARD. SURFACE TEMPERATURES THEN BECOME FOCUS AND FOR NOW HAVE SUB-FREEZING TEMPERATURES ACROSS FAR WESTERN AND NORTHERN CWA FRIDAY NIGHT INTO SATURDAY...WITH COLD AIR COLLAPSING SOUTHWARD SATURDAY NIGHT BEHIND DEPARTING TROUGH. FORECAST SOUNDINGS SUGGEST POTENTIAL FOR FREEZING RAIN IN THE FAR NORTHERN/WESTERN SECTIONS GIVEN THE COLDER SURFACE TEMPERATURES TOPPED BY WARM LAYER ABOVE 925MB. HOWEVER...STILL HAVE ENOUGH UNCERTAINTY IN LOW LEVEL TEMPS AT THIS RANGE THAT DECIDED TO HOLD OFF MENTIONING FREEZING RAIN FOR NOW...INSTEAD GOING WITH RAIN OR SNOW WORDING ACROSS OUR NORTH AND WEST...GENERALLY IN THOSE AREAS NORTHWEST OF INVERTED TROUGH. WILL ADD MENTION OF FREEZING RAIN TO THE HWO THIS MORNING THOUGH...TO HEIGHTEN AWARENESS OF POTENTIAL FOR ICING GIVEN TIMING OF THIS EVENT COINCIDING WITH SOUTH DAKOTA GIRLS BASKETBALL TOURNAMENT TAKING PLACE IN VARIOUS LOCATIONS INCLUDING HURON THIS WEEKEND. BY SATURDAY NIGHT/SUNDAY...COOLING BEHIND THE SYSTEM SHOULD CHANGE PRECIP OVER TO SNOW...THOUGH PRECIP SHOULD ALSO BE WANING THROUGH THAT PERIOD SO NOT EXPECTING LARGE AMOUNTS OF SNOWFALL AT THIS TIME. GENERALLY QUIET WEATHER RETURNS FOR EARLY NEXT WEEK. COULD SEE SOME LIGHT PRECIP IN NORTHWEST FLOW PATTERN...BUT GIVEN SOME UNCERTAINTY IN PATTERN AND AVAILABLE MOISTURE...WILL KEEP DRY FOR NOW WITH TEMPERATURES REMAINING ON THE COOL SIDE OF SEASONAL NORMALS. && .AVIATION.../FOR THE 18Z TAF ISSUANCE/ QUICKLY LOOPING THROUGH THE VISIBLE SATELLITE SHOWS THAT THE EXISTING STRATUS IS PRETTY THIN AND AT THIS TIME FAIRLY QUICKLY ERODING FROM THE SOUTHWEST. THE RAP HAS US MIRED IN THE GUNK THROUGH LATE TONIGHT WHILE THE OTHER MODELS TEMPORARILY BREAK US OUT OF THE LOW END MVFR CEILINGS...THEN SUGGEST REDEVELOPMENT LATER TONIGHT. NO EASY ANSWER HERE AS SOME QUESTION THAT IF STRATUS IS ABLE TO DISSIPATE THIS AFTERNOON AN INCREASING SOUTHERLY GRADIENT MAY MAKE IT DIFFICULT TO REDEVELOP. HOWEVER...WILL LEAN TOWARDS THE MORE PESSIMISTIC SOLUTION AND PLAN ON THE STRATUS REDEVELOPING UNDER A FAIRLY STRONG INVERSION AND THINKING MVFR TO IFR CEILINGS OVERNIGHT MOST LOCATIONS. /08 && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
445 AM CST WED MAR 6 2013 .DISCUSSION.../ISSUED AT 445 AM CST/ LOOKS LIKE A QUIET COUPLE OF DAYS ACROSS THE REGION...BUT THAT DOES NOT MEAN THE FORECAST IS WITHOUT ITS CHALLENGES. OF PRIMARY CONCERN TODAY IS WIDESPREAD STRATUS WHICH IS NOW STUCK UNDER SURFACE RIDGE ADVANCING SLOWLY EASTWARD TODAY. OTHER THAN HIGH-RESOLUTION SHORT RANGE MODELS...WHICH SEEM TO HAVE BETTER GRASP ON CURRENT REALITY... HAVE LITTLE USEFUL GUIDANCE TO FOLLOW REGARDING PERSISTENCE OF THE LOW LEVEL MOISTURE. THUS FOLLOWED MORE PESSIMISTIC RAP/HRRR VIEW... HOLDING ONTO EXTENSIVE CLOUD COVER MUCH OF THE DAY WITH POSSIBILITY OF SOME HOLES DEVELOPING IN THE LATE AFTERNOON AS MARCH SUN HAS A CHANCE TO ERODE AROUND ANY BREAKS WHICH MAY DEVELOP. GREATER CLOUD COVER WILL LEAD TO COOLER TEMPS...THOUGH PREVIOUS FORECAST ALREADY ON THE COOL SIDE WITH LIGHT FLOW ACROSS THE EAST SO DID NOT LOWER HIGHS TOO MUCH AT THIS POINT. FOR TONIGHT...NAM LOW LEVEL MOISTURE HINTS AT POTENTIAL FOR STRATUS TO REDEVELOP ACROSS CENTRAL SD AS RETURN SOUTHERLY FLOW DRAWS DEEPER MOISTURE NORTHWARD BEHIND THE DEPARTING RIDGE. IF THIS DOES DEVELOP IT COULD LINGER INTO AT LEAST MIDDAY THURSDAY...AGAIN IMPACTING HIGH TEMPERATURES AND COOLED HIGHS IN THE WEST BY A FEW DEGREES...THOUGH WITH 925MB TEMPERATURES ANYWHERE FROM 4-6C...COULD STILL MIX INTO THE MID TO UPPER 40S WEST OF THE JAMES RIVER. ATTENTION THEN TURNS TO WEEKEND SYSTEM...WHICH MODELS HAVE COME INTO SLIGHTLY BETTER AGREEMENT ON WHEN COMPARED TO PAST COUPLE OF NIGHTS. FAVORED SOLUTION DEPICTS STRONGER BUT PROGRESSIVE NORTHERN STREAM TROUGH MOVING EAST ACROSS NORTH DAKOTA/MINNESOTA SATURDAY/SATURDAY NIGHT...WHICH DOES NOT ALLOW SOUTHERN STREAM CUTOFF LOW TO SWING NORTH AND STRENGTHEN AS HAS BEEN SEEN IN PREVIOUS ECMWF RUNS. THIS SOLUTION DOES GIVE THIS AREA A GOOD CHANCE OF SOME DECENT PRECIP... WITH GOOD CONSENSUS POINTING TO LATE FRIDAY NIGHT THROUGH SATURDAY NIGHT AS PERIODS WITH GREATEST POTENTIAL. COULD SEE SOME LIGHT PRECIP BREAK OUT ACROSS THE WEST ALREADY BY FRIDAY AFTERNOON...AS BROAD WARM ADVECTION BEGINS TO KICK IN. THIS BROAD LIFT ACROSS INVERTED TROUGH REMAINS PERSISTENT INTO FRIDAY NIGHT...WITH GROWING CONFIDENCE FOR BUMPING POPS INTO LIKELY RANGE ACROSS MUCH OF THE AREA LATE FRIDAY NIGHT AND SATURDAY. WILL CARRY LIKELY POPS INTO SATURDAY NIGHT OVER THE SOUTHEAST HALF OF THE CWA AS BOUNDARY IS PULLED EAST OF THE AREA BY DEPARTING NORTHERN STREAM WAVE. WHILE CONFIDENCE IN PRECIPITATION CHANCE IS GROWING...PRECIPITATION TYPE BECOMES A HUGE QUESTION MARK. GFS/ECMWF BOTH PUMP WARM AIR WELL NORTH ACROSS THE REGION...WITH FREEZING LINE NEAR ND/SD BORDER AT 850MB...AND NEAR THE NORTHERN EDGE OF OUR FORECAST AREA AT 925MB BY FRIDAY EVENING. CONTINUED SOUTHERLY FLOW ACROSS THE AREA FRIDAY NIGHT KEEPS THE WARM LAYER LOCKED IN PLACE AT LEAST INTO SATURDAY MORNING...WITH COOLING ONLY TAKING PLACE IN THE WEST BY SATURDAY AFTERNOON/EVENING AS INVERTED TROUGH BEGINS TO ADVANCE EASTWARD. SURFACE TEMPERATURES THEN BECOME FOCUS AND FOR NOW HAVE SUB-FREEZING TEMPERATURES ACROSS FAR WESTERN AND NORTHERN CWA FRIDAY NIGHT INTO SATURDAY...WITH COLD AIR COLLAPSING SOUTHWARD SATURDAY NIGHT BEHIND DEPARTING TROUGH. FORECAST SOUNDINGS SUGGEST POTENTIAL FOR FREEZING RAIN IN THE FAR NORTHERN/WESTERN SECTIONS GIVEN THE COLDER SURFACE TEMPERATURES TOPPED BY WARM LAYER ABOVE 925MB. HOWEVER...STILL HAVE ENOUGH UNCERTAINTY IN LOW LEVEL TEMPS AT THIS RANGE THAT DECIDED TO HOLD OFF MENTIONING FREEZING RAIN FOR NOW...INSTEAD GOING WITH RAIN OR SNOW WORDING ACROSS OUR NORTH AND WEST...GENERALLY IN THOSE AREAS NORTHWEST OF INVERTED TROUGH. WILL ADD MENTION OF FREEZING RAIN TO THE HWO THIS MORNING THOUGH...TO HEIGHTEN AWARENESS OF POTENTIAL FOR ICING GIVEN TIMING OF THIS EVENT COINCIDING WITH SOUTH DAKOTA GIRLS BASKETBALL TOURNAMENT TAKING PLACE IN VARIOUS LOCATIONS INCLUDING HURON THIS WEEKEND. BY SATURDAY NIGHT/SUNDAY...COOLING BEHIND THE SYSTEM SHOULD CHANGE PRECIP OVER TO SNOW...THOUGH PRECIP SHOULD ALSO BE WANING THROUGH THAT PERIOD SO NOT EXPECTING LARGE AMOUNTS OF SNOWFALL AT THIS TIME. GENERALLY QUIET WEATHER RETURNS FOR EARLY NEXT WEEK. COULD SEE SOME LIGHT PRECIP IN NORTHWEST FLOW PATTERN...BUT GIVEN SOME UNCERTAINTY IN PATTERN AND AVAILABLE MOISTURE...WILL KEEP DRY FOR NOW WITH TEMPERATURES REMAINING ON THE COOL SIDE OF SEASONAL NORMALS. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ STRATUS HAS CONTINUED TO EXPAND WITH DECREASING WINDS AND DIRECTION BECOMING MORE NORTHEASTERLY. MODELS NOT HANDLING THE STRATUS WELL AT ALL...WITH THE RAP BEING THE ONLY MODEL SUGGESTING STRATUS CURRENTLY EXISTS ACROSS THE AREA. HAVE KEPT STRATUS ACROSS THE AREA THROUGH THE OVERNIGHT...WITH CEILINGS LOWERING SLIGHTLY AROUND SUNRISE. MODEL SOUNDINGS SUGGEST OUTSIDE CHANCE OF STRATUS LOWERING TO THE GROUND NEAR KHON...BUT CONFIDENCE NOT THERE AT THIS POINT TO PUT INTO THE TAF. AT KFSD AND KSUX...STRATUS MAY DIP INTO THE IFR RANGE BEFORE RECOVERING INTO THE MVFR CATEGORY. WILL BE HARD TO SHAKE THE STRATUS TOMORROW WITH LIGHT SOUTHEASTERLY FLOW DEVELOPING...AND KEPT STRATUS THROUGHOUT THE DAY. SOUNDINGS DON/T HAVE MUCH TO WORK OFF OF BY TOMORROW EVENING...BUT KEPT STRATUS WITH REINFORCING SOUTHEASTERLY FLOW. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1050 PM CST TUE MAR 5 2013 .DISCUSSION.../ISSUED AT 840 PM CST/ LARGE SWATH OF LOW STRATUS REMAINS LARGELY UNCHANGED FROM THIS AFTERNOON...AS THE LOW LEVEL NORTH NORTHWEST FLOW CONTINUES TO STREAM THE STRATUS ACROSS THE FORECAST AREA. SOME THINNING IS OBSERVED ACROSS SOUTH CENTRAL SOUTH DAKOTA AND FAR NORTHEAST NEBRASKA...BUT OVERALL...DO NOT ANTICIPATE MUCH IF ANY PUSH EASTWARD TONIGHT. COULD SEE SOME THINNING IN THE WEST LATE TONIGHT AS THE SURFACE RIDGE TRACKS THROUGH THE REGION...BUT WITH SUCH LIGHT FLOW WE COULD VERY WELL SEE THE STRATUS HANG ON THROUGH WEDNESDAY MORNING. WITH THE BULK OF THE FORECAST AREA LIKELY TO SEE CONSIDERABLE CLOUD COVERAGE OVERNIGHT...HAVE RAISED LOWS A FEW DEGREES. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ STRATUS HAS CONTINUED TO EXPAND WITH DECREASING WINDS AND DIRECTION BECOMING MORE NORTHEASTERLY. MODELS NOT HANDLING THE STRATUS WELL AT ALL...WITH THE RAP BEING THE ONLY MODEL SUGGESTING STRATUS CURRENTLY EXISTS ACROSS THE AREA. HAVE KEPT STRATUS ACROSS THE AREA THROUGH THE OVERNIGHT...WITH CEILINGS LOWERING SLIGHTLY AROUND SUNRISE. MODEL SOUNDINGS SUGGEST OUTSIDE CHANCE OF STRATUS LOWERING TO THE GROUND NEAR KHON...BUT CONFIDENCE NOT THERE AT THIS POINT TO PUT INTO THE TAF. AT KFSD AND KSUX...STRATUS MAY DIP INTO THE IFR RANGE BEFORE RECOVERING INTO THE MVFR CATEGORY. WILL BE HARD TO SHAKE THE STRATUS TOMORROW WITH LIGHT SOUTHEASTERLY FLOW DEVELOPING...AND KEPT STRATUS THROUGHOUT THE DAY. SOUNDINGS DON/T HAVE MUCH TO WORK OFF OF BY TOMORROW EVENING...BUT KEPT STRATUS WITH REINFORCING SOUTHEASTERLY FLOW. && .PREV DISCUSSION.../ISSUED AT 300 PM CST/ WIDESPREAD STRATUS ALONG AND EAST OF THE JAMES RIVER WILL BE SLOW TO CLEAR FROM WEST TO EAST OVERNIGHT. MODELS APPEAR TOO FAST IN CLEARING THE STRATUS OUT AND WILL KEEP AREAS EAST OF I29 MOSTLY CLOUDY OVERNIGHT WITH CLEARING TOWARDS MORNING. THIS SHOULD ALSO HELP HOLD TEMPERATURES UP ACROSS THE EAST AND HAVE BUMPED LOWS UP THERE 2 TO 4 DEGREES. THE BIG QUESTION FOR WEDNESDAY WILL BE THE CLOUD COVER. IF STRATUS DOES NOT CLEAR ACROSS THE EAST LATER TONIGHT...WEAK LOW LEVEL EASTERLY FLOW ON WEDNESDAY MAY KEEP THE STRATUS IN ALL DAY AND WILL HOLD THE TEMPERATURES DOWN. AM NOT CONFIDENT CLEARING WILL OCCUR SO WILL BE A TAD BIT MORE PESSIMISTIC AND GO WITH PARTLY CLOUDY ACROSS THE EAST. WILL KEEP HIGHS GENERALLY IN THE 20S EAST OF I29 AND IN THE 30S TO LOWER 40S WEST WITH THE WARMEST TEMPERATURES ACROSS THE SOUTHWEST CWA. EXPECT SKIES SHOULD FINALLY GO MOSTLY CLEAR...FOR A SPELL... WEDNESDAY NIGHT AS SUBSIDENCE FROM THE HIGH AND A LIGHT EASTERLY FLOW OF DRY AIR STARTING AS THE HIGH MOVES EAST WORK TOGETHER. CLOUDS...THEY SHOULD BE MIDDLE AND HIGH...SHOULD LATER WORK THEIR WAY SLOWLY BACK OVER THE AREA THURSDAY THROUGH FRIDAY IN WARMING PATTERN. NO PRECIPITATION THREAT SEEN THESE TWO DAYS THROUGH FRIDAY AFTERNOON. TEMPERATURES WILL WARM THOUGH SURFACE WARMING WILL LIKELY BE LIMITED AS THE LOW LEVEL FLOW BEGINS TO BACK AGAIN TO MORE EASTERLY FRIDAY AFTER GOING SOUTHERLY. GUIDANCE TEMPERATURES DO NOT LOOK BAD. FOR NOW...CLOUD COVER AND DEVELOPING EASTERLY/SOUTHEAST FLOW IS EXPECTED TO LIMIT THE CHANCE OF ANY LATE NIGHT FOG AFTER DAYTIME SNOWMELT SO WILL KEEP OUT. MEDIUM RANGE MODELS HAVE...FOR NOW...REACHED A CONSENSUS ON A STRONGER CANADIAN NORTHERN STREAM KEEPING POTENTIALLY WET WEEKEND SYSTEM MOSTLY TO THE SOUTH OF OUR AREA. THE EC IN PARTICULAR HAD BEEN GOING ON THE NORTHERN TRACK AND WET SIDE FOR OUR AREA UP TO TODAY. HAVE REACHED AGREEMENT WITH NEIGHBORS ON KEEPING PRECIP MENTION BUT LOWERING POPS SOME FOR THE WEEKEND...THEN ALLOW FOR THE CHASING OUT OF THE SYSTEM BY THE START OF NEXT WEEK. THE CANADIAN RIDGING PARTLY RESPONSIBLE FOR THIS CHANGE SHOULD ALSO KEEP TEMPERATURES TO NEAR SEASONAL LEVELS...THOUGH THIS WILL BE A LOT COOLER THAN THE RECORD SMASHING TEMPERATURES WE WERE GETTING AT THE SAME TIME LAST YEAR. NOT TIME FOR GOLF...YET. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
REFER TO THE MAIN FORECAST DISCUSSION SECTION FOR MORE ABOUT SKY
COVER TONIGHT.
EXPECT MVFR CLOUDS TO VERY GRADUALLY ERODE AWAY FROM WEST TO EAST OVERNIGHT...ALTHOUGH THERE IS A LOT OF UNCERTAINTY ABOUT THE SPEED OF THE CLEARING...IF IT OCCURS AT ALL. IF SKIES CLEAR...PATCHY FOG WILL BE POSSIBLE. MAINLY CLEAR SKIES/VFR CONDITIONS EXPECTED THURSDAY. && .MARINE... NORTHWEST WINDS IN THE NSH WATERS HAVE DIMINISHED BELOW SMALL CRAFT ADVISORY CRITERIA. WILL ALLOW THE ADVY TO EXPIRE FOR THE NORTHERN NEARSHORE MARINE ZONES...AND KEEP THE SOUTHERN ONE THROUGH 6 PM DUE TO LINGERING LARGE WAVES TOWARD THE OPEN WATERS. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...SMALL CRAFT ADVISORY UNTIL 6 PM CST THIS EVENING FOR LMZ645-646. SMALL CRAFT ADVISORY UNTIL 4 PM CST THIS AFTERNOON FOR LMZ643- 644. && $$ TONIGHT/THURSDAY AND AVIATION/MARINE...MRC THURSDAY NIGHT THROUGH WEDNESDAY...MEB
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1213 PM CST WED MAR 6 2013 .SHORT TERM...TODAY THROUGH FRIDAY 328 AM CST WED MAR 6 2013 FORECAST CONCERNS ARE ON FOG/FREEZING FOG POTENTIAL TONIGHT INTO THURSDAY MORNING AND TEMPERATURES THROUGH FRIDAY. FOCUS THEN QUICKLY TURNS TO PRECIPITATION TYPE CONCERNS THIS WEEKEND AND THE POTENTIAL FOR MODERATE TO HEAVY RAINFALL ACROSS PARTS OF THE AREA. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED LOW PRESSURE OVER THE CENTRAL APPALACHIANS. A TROUGH WAS NOTED ALONG THE MINNESOTA/ONTARIO BORDER. AN UPPER RIDGE WAS BUILDING ACROSS THE WESTERN CONUS WITH A TROUGH MOVING ONTO THE WEST COAST. SURFACE OBSERVATIONS INDICATED A RIDGE OF HIGH PRESSURE EXTENDING FROM THE THE DAKOTAS SOUTH THROUGH THE SOUTHERN PLAINS. A SURFACE LOW WAS NOTED OVER VIRGINIA WITH AN INVERTED TROUGH EXTENDING NORTHWEST INTO FAR SOUTHEAST WISCONSIN. THE TROUGH ALONG THE MINNESOTA/ONTARIO BORDER WILL PROGRESS EAST TODAY ACROSS LAKE SUPERIOR AS THE SURFACE RIDGE EDGES EAST INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE MAIN FORECAST CHALLENGE TODAY WILL BE CLOUD COVER. THERE ARE CURRENTLY PLENTY OF HOLES IN THE STRATUS LAYER OVER EASTERN MINNESOTA INTO SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SHOW LOW LEVEL CLOUDS LINGERING THROUGH THE MORNING HOURS BEFORE FINALLY CLEARING LATE THIS AFTERNOON. THE FORECAST MODELS HAVE BEEN STRUGGLING WITH DEWPOINTS LATELY SO NOT SOLD ON THE CLOUDS HOLDING ON AS LONG AS THE MODELS SUGGEST. DECIDED TO GO WITH HIGHER CLOUD COVER THIS MORNING OVER THE PREVIOUS FORECAST...WITH CLEARING OCCURRING FROM WEST TO EAST DURING THE MID TO LATE AFTERNOON HOURS. THE NEXT CONCERN IS THE POTENTIAL FOR FOG/FREEZING FOG TONIGHT. FOG WOULD BE MORE FAVORABLE IF THE CLOUDS HOLD ON TODAY. SREF GUIDANCE AND FORECAST SOUNDINGS CONTINUE TO SUGGEST FOG DEVELOPMENT TONIGHT. LOOKING BACK TO THE WEST...UNDER THE SURFACE RIDGE...FOG HAS DEVELOPED. THE SREF PROBABILITIES ARE CAPTURING THIS SO FEEL THEY ARE DOING A DECENT JOB ON CAPTURING THE FOG. WILL MAINTAIN AREAS OF FOG IN THE FORECAST OVERNIGHT INTO THURSDAY MORNING. VISIBILITIES COULD BE REDUCED TO LESS THAN 1/2 MILE. ALSO...THE FOG COULD FREEZE TO OBJECTS CREATING HOAR FROST. SOME LIGHT ICING MAY OCCUR ON AREA ROADS...BUT THE RECENTLY APPLIED TREATMENT ON THE ROADS COULD REALLY LIMIT ICING POTENTIAL. PLAN ON LOWS FALLING INTO THE SINGLE DIGITS TONIGHT. FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH CENTRAL WISCONSIN WILL SEE TEMPERATURES FALL INTO THE SINGLE DIGITS BELOW ZERO. HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY PROVIDING QUIET WEATHER. LOOK FOR MOSTLY SUNNY SKIES ON THURSDAY WITH HIGHS IN THE UPPER 20S TO LOWER 30S. SURFACE HIGH PRESSURE IS EXPECTED TO SLIDE EAST OF THE AREA ON FRIDAY AS A POTENT TROUGH DIVES INTO THE SOUTHWEST CONUS. MEANWHILE LOW PRESSURE DEVELOPS OVER EASTERN COLORADO AS A WARM FRONT LIFTS NORTH OUT OF THE CENTRAL PLAINS. TWO MAIN FEATURES TO WATCH CLOSELY ON FRIDAY...A NORTHERN STREAM TROUGH DIVING SOUTH OUT OF CENTRAL SASKATCHEWAN AND THE SOUTHWEST LOW LIFTING NORTHEAST TOWARD THE REGION. THE WARM FRONT LOOKS TO LIFT NORTH INTO SOUTHERN MINNESOTA/SOUTHERN WISCONSIN FRIDAY NIGHT INTO SATURDAY MORNING THEN LIFTING NORTH THROUGH THE DAY ON SATURDAY. THE NORTHERN STREAM WAVE AND ENERGY EJECTING OUT OF THE SOUTHWEST WILL INTERACT WITH THE FRONT BRINGING PRECIPITATION TO THE AREA. WARM AIR ALOFT WILL SURGE INTO THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT LEADING TO A MIX OF PRECIPITATION TYPES. A MIX OF FREEZING RAIN...SLEET AND SNOW IS EXPECTED FRIDAY EVENING INTO EARLY SATURDAY MORNING SWITCHING OVER TO MAINLY RAIN DURING THE DAY ON SATURDAY. SOME ICE ACCUMULATION IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A MOISTURE RICH AIRMASS MOVES INTO THE AREA DURING THE DAY ON SATURDAY WITH PRECIPITABLE WATER VALUES APPROACHING 270 PERCENT OF NORMAL. ALSO...TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO LOWER 40S. 925/850 MB MOISTURE TRANSPORT FOCUSES INTO SOUTHERN WISCONSIN AND FAR NORTHEAST IOWA SATURDAY INTO SATURDAY NIGHT. PERIODS OF MODERATE TO HEAVY RAINFALL LOOK POSSIBLE SATURDAY INTO SATURDAY NIGHT LEADING TO LOCALIZED FLOODING AND ICE JAMS ON AREA RIVERS. FORECAST MODELS ARE JUST STARTING TO COME INTO AGREEMENT ON THIS WARMER AND WET SOLUTION SO WILL HAVE TO KEEP A CLOSE WATCH ON THE NEXT FEW RUNS. .LONG TERM...SATURDAY THROUGH TUESDAY 328 AM CST WED MAR 6 2013 06.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY INTO SATURDAY NIGHT BUT THEN START TO DIVERGE SUNDAY INTO EARLY MONDAY. THE ECMWF SHIFTS THE BOUNDARY SOUTHEAST AND EAST OF THE AREA AS AN UPPER LOW WRAPS UP OVER THE OHIO RIVER VALLEY. THE GFS LEANS TOWARD THIS SOLUTION BUT IT IS FASTER THAN THE ECMWF...TAKING THE LOW NORTH INTO THE EASTERN GREAT LAKES EARLY ON MONDAY. THE GEM OFFERS A DIFFERENT SOLUTION WITH THE LOW TAKING SHAPE OVER NORTHERN ILLINOIS WHICH WOULD BRING SIGNIFICANT SNOWFALL TO NORTHERN WISCONSIN THROUGH SOUTHERN/CENTRAL MINNESOTA. HAVE LEANED TOWARD A MODEL CONSENSUS BLEND APPROACH MONDAY INTO TUESDAY WITH CHANCES FOR SNOW MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE AREA. SNOW CHANCES WILL CONTINUE ACROSS NORTH CENTRAL WISCONSIN ON TUESDAY AS SHORTWAVE MOVES ACROSS NORTHERN WISCONSIN. PLAN ON TEMPERATURES COOLING SLIGHTLY EARLY NEXT WEEK WITH HIGHS FALLING INTO THE 30S AND LOWS IN THE TEENS TO LOWER 20S. && .AVIATION...THROUGH 18Z THURSDAY 1212 PM CST WED MAR 6 2013 FORECAST IS OF LOWER CONFIDENCE...ESPECIALLY FURTHER WEST AT KRST. SATELLITE IMAGERY INDICATING A VERY EXPANSIVE MVFR CLOUD DECK ACROSS THE REGION WITH SOME OLES OPENING UP INTO MVFR SCT/BKN CONDITIONS /THUS THE TEMPO IN THE TAFS/. THE CLOUD LAYER IS VERY THIN PER SATELLITE IMAGERY AS RIVERS ARE VISIBLE THROUGH IT. ANOTHER SOMEWHAT DRYING PUSH OF AIR IS COMING IN FROM THE NORTH ASSOCIATED WITH A WEATHER SYSTEM TRAVELING ACROSS CANADA. THIS LOOKS TO POSSIBLY PROVIDE AN INFLUENCE OF CLOUD DIMINISHMENT BY EVENING AND AFTER FROM THE NORTH. HOWEVER...THE LOW LEVEL MOISTURE IS SITUATED WITHIN THE SURFACE RIDGE WITH LIGHT WIND FLOW OVER MN/DAKOTAS. THIS SURFACE RIDGING WILL SHIFT EAST AND BE LOCATED OVER THE MISS RIVER /KLSE/ BY MORNING. THIS MORNING...WEST OF THE RIDGE AXIS...LIFR CONDITIONS OCCURRED AND FG/CIGS IN THE LIFR RANGE. EXTRAPOLATING THIS TO THU MORNING...THIS LIFR SYNOPTIC AREA WOULD BE OVER MN WITH KRST ON THE EASTERN EDGE. SHORT RANGE MODEL ENSEMBLES /SREF/ INDICATE A HIGHER PROBABILITY OF IFR ALONG AND WEST OF I-35...BUT VERY CLOSE TO KRST. THIS AFTERNOON...MARCH SUN ANGLES WILL WORK ON THINNING THE CLOUDS AND EXPANDING THE PATCHES OF SCT/BKN OPENING UP. PREVIOUS FORECAST HAD SCT CLOUDS BY LATE AFTERNOON...AND THEN MVFR BR FORMING. ALTHOUGH CLOUDS ARE STILL WIDESPREAD AT 18Z...HAVE STAYED THE COURSE ON CLEARING BY LATE AFTERNOON. BUT CONFIDENCE IS VERY LOW AND MVFR CIGS COULD VERY WELL BE IN PLACE OVERNIGHT. IF THIS OCCURS...WOULD THINK KRST COULD LOWER TO IFR CIGS BY MORNING. KLSE SHOULD REMAIN MVFR. OVERALL...THIS FORECAST IS THE MOST OPTIMISTIC VERSION AT THIS TIME AND FORECAST CHANGES WOULD PROBABLY BE TOWARD WORSENING THE CIG/VSBYS. && .ARX WATCHES/WARNINGS/ADVISORIES... 328 AM CST WED MAR 6 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...BAUMGARDT
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
513 AM CST WED MAR 6 2013 .SHORT TERM...TO0DAY THROUGH FRIDAY 328 AM CST WED MAR 6 2013 FORECAST CONCERNS ARE ON FOG/FREEZING FOG POTENTIAL TONIGHT INTO THURSDAY MORNING AND TEMPERATURES THROUGH FRIDAY. FOCUS THEN QUICKLY TURNS TO PRECIPITATION TYPE CONCERNS THIS WEEKEND AND THE POTENTIAL FOR MODERATE TO HEAVY RAINFALL ACROSS PARTS OF THE AREA. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED LOW PRESSURE OVER THE CENTRAL APPALACHIANS. A TROUGH WAS NOTED ALONG THE MINNESOTA/ONTARIO BORDER. AN UPPER RIDGE WAS BUILDING ACROSS THE WESTERN CONUS WITH A TROUGH MOVING ONTO THE WEST COAST. SURFACE OBSERVATIONS INDICATED A RIDGE OF HIGH PRESSURE EXTENDING FROM THE THE DAKOTAS SOUTH THROUGH THE SOUTHERN PLAINS. A SURFACE LOW WAS NOTED OVER VIRGINIA WITH AN INVERTED TROUGH EXTENDING NORTHWEST INTO FAR SOUTHEAST WISCONSIN. THE TROUGH ALONG THE MINNESOTA/ONTARIO BORDER WILL PROGRESS EAST TODAY ACROSS LAKE SUPERIOR AS THE SURFACE RIDGE EDGES EAST INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE MAIN FORECAST CHALLENGE TODAY WILL BE CLOUD COVER. THERE ARE CURRENTLY PLENTY OF HOLES IN THE STRATUS LAYER OVER EASTERN MINNESOTA INTO SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SHOW LOW LEVEL CLOUDS LINGERING THROUGH THE MORNING HOURS BEFORE FINALLY CLEARING LATE THIS AFTERNOON. THE FORECAST MODELS HAVE BEEN STRUGGLING WITH DEWPOINTS LATELY SO NOT SOLD ON THE CLOUDS HOLDING ON AS LONG AS THE MODELS SUGGEST. DECIDED TO GO WITH HIGHER CLOUD COVER THIS MORNING OVER THE PREVIOUS FORECAST...WITH CLEARING OCCURRING FROM WEST TO EAST DURING THE MID TO LATE AFTERNOON HOURS. THE NEXT CONCERN IS THE POTENTIAL FOR FOG/FREEZING FOG TONIGHT. FOG WOULD BE MORE FAVORABLE IF THE CLOUDS HOLD ON TODAY. SREF GUIDANCE AND FORECAST SOUNDINGS CONTINUE TO SUGGEST FOG DEVELOPMENT TONIGHT. LOOKING BACK TO THE WEST...UNDER THE SURFACE RIDGE...FOG HAS DEVELOPED. THE SREF PROBABILITIES ARE CAPTURING THIS SO FEEL THEY ARE DOING A DECENT JOB ON CAPTURING THE FOG. WILL MAINTAIN AREAS OF FOG IN THE FORECAST OVERNIGHT INTO THURSDAY MORNING. VISIBILITIES COULD BE REDUCED TO LESS THAN 1/2 MILE. ALSO...THE FOG COULD FREEZE TO OBJECTS CREATING HOAR FROST. SOME LIGHT ICING MAY OCCUR ON AREA ROADS...BUT THE RECENTLY APPLIED TREATMENT ON THE ROADS COULD REALLY LIMIT ICING POTENTIAL. PLAN ON LOWS FALLING INTO THE SINGLE DIGITS TONIGHT. FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH CENTRAL WISCONSIN WILL SEE TEMPERATURES FALL INTO THE SINGLE DIGITS BELOW ZERO. HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY PROVIDING QUIET WEATHER. LOOK FOR MOSTLY SUNNY SKIES ON THURSDAY WITH HIGHS IN THE UPPER 20S TO LOWER 30S. SURFACE HIGH PRESSURE IS EXPECTED TO SLIDE EAST OF THE AREA ON FRIDAY AS A POTENT TROUGH DIVES INTO THE SOUTHWEST CONUS. MEANWHILE LOW PRESSURE DEVELOPS OVER EASTERN COLORADO AS A WARM FRONT LIFTS NORTH OUT OF THE CENTRAL PLAINS. TWO MAIN FEATURES TO WATCH CLOSELY ON FRIDAY...A NORTHERN STREAM TROUGH DIVING SOUTH OUT OF CENTRAL SASKATCHEWAN AND THE SOUTHWEST LOW LIFTING NORTHEAST TOWARD THE REGION. THE WARM FRONT LOOKS TO LIFT NORTH INTO SOUTHERN MINNESOTA/SOUTHERN WISCONSIN FRIDAY NIGHT INTO SATURDAY MORNING THEN LIFTING NORTH THROUGH THE DAY ON SATURDAY. THE NORTHERN STREAM WAVE AND ENERGY EJECTING OUT OF THE SOUTHWEST WILL INTERACT WITH THE FRONT BRINGING PRECIPITATION TO THE AREA. WARM AIR ALOFT WILL SURGE INTO THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT LEADING TO A MIX OF PRECIPITATION TYPES. A MIX OF FREEZING RAIN...SLEET AND SNOW IS EXPECTED FRIDAY EVENING INTO EARLY SATURDAY MORNING SWITCHING OVER TO MAINLY RAIN DURING THE DAY ON SATURDAY. SOME ICE ACCUMULATION IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A MOISTURE RICH AIRMASS MOVES INTO THE AREA DURING THE DAY ON SATURDAY WITH PRECIPITABLE WATER VALUES APPROACHING 270 PERCENT OF NORMAL. ALSO...TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO LOWER 40S. 925/850 MB MOISTURE TRANSPORT FOCUSES INTO SOUTHERN WISCONSIN AND FAR NORTHEAST IOWA SATURDAY INTO SATURDAY NIGHT. PERIODS OF MODERATE TO HEAVY RAINFALL LOOK POSSIBLE SATURDAY INTO SATURDAY NIGHT LEADING TO LOCALIZED FLOODING AND ICE JAMS ON AREA RIVERS. FORECAST MODELS ARE JUST STARTING TO COME INTO AGREEMENT ON THIS WARMER AND WET SOLUTION SO WILL HAVE TO KEEP A CLOSE WATCH ON THE NEXT FEW RUNS. .LONG TERM...SATURDAY THROUGH TUESDAY 328 AM CST WED MAR 6 2013 06.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY INTO SATURDAY NIGHT BUT THEN START TO DIVERGE SUNDAY INTO EARLY MONDAY. THE ECMWF SHIFTS THE BOUNDARY SOUTHEAST AND EAST OF THE AREA AS AN UPPER LOW WRAPS UP OVER THE OHIO RIVER VALLEY. THE GFS LEANS TOWARD THIS SOLUTION BUT IT IS FASTER THAN THE ECMWF...TAKING THE LOW NORTH INTO THE EASTERN GREAT LAKES EARLY ON MONDAY. THE GEM OFFERS A DIFFERENT SOLUTION WITH THE LOW TAKING SHAPE OVER NORTHERN ILLINOIS WHICH WOULD BRING SIGNIFICANT SNOWFALL TO NORTHERN WISCONSIN THROUGH SOUTHERN/CENTRAL MINNESOTA. HAVE LEANED TOWARD A MODEL CONSENSUS BLEND APPROACH MONDAY INTO TUESDAY WITH CHANCES FOR SNOW MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE AREA. SNOW CHANCES WILL CONTINUE ACROSS NORTH CENTRAL WISCONSIN ON TUESDAY AS SHORTWAVE MOVES ACROSS NORTHERN WISCONSIN. PLAN ON TEMPERATURES COOLING SLIGHTLY EARLY NEXT WEEK WITH HIGHS FALLING INTO THE 30S AND LOWS IN THE TEENS TO LOWER 20S. && .AVIATION...TODAY AND TONIGHT 513 AM CST WED MAR 6 2013 THE MAIN AVIATION CONCERNS ARE WHEN WILL THE MVFR STRATUS CLEAR OUT AND POTENTIAL FOR FOG TONIGHT. MVFR STRATUS ENCOMPASSES BOTH TAF SITES EARLY THIS MORNING... THOUGH THERE ARE SOME POCKETS OF CLEAR SKIES ACROSS CENTRAL AND EASTERN MINNESOTA. ANTICIPATING THAT THE COMBINATION OF SUNSHINE AND HIGH PRESSURE BUILDING IN FROM THE PLAINS WILL SLOWLY BUT SURELY BREAK UP THE STRATUS. THE POCKETS OF CLEAR SKIES...IF THEY CAN HOLD TOGETHER UNTIL THE SUN COMES UP...WILL HELP AS WELL TO MIX OUT THE STRATUS. KEPT THE PREVIOUS FORECAST IDEA OF A LATE SCATTERING OUT TREND...BETWEEN 23-00Z. PLENTY OF UNCERTAINTY EXISTS ON THIS...HOWEVER...AND IT COULD CLEAR EARLIER OR LATER. IT DOES APPEAR THAT EVEN IN THE PESSIMISTIC CLEARING SCENARIO...THAT BY 06Z BOTH TAF SITES WOULD BE CLEARED OUT. WITH LIGHT WINDS...THE RIDGE AXIS IN PLACE AND LINGERING LOW LEVEL MOISTURE...CONCERN THEN SHIFTS TO FOG. CERTAINLY POTENTIAL FOR DENSE FOG FORMATION...ESPECIALLY IF THE LATE IN THE DAY CLEARING OCCURS AS FORECAST. FOR NOW INCLUDED MVFR BR AT BOTH SITES...BUT AGAIN THIS COULD END UP LOWER. && .ARX WATCHES/WARNINGS/ADVISORIES... 328 AM CST WED MAR 6 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...AJ
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
328 AM CST WED MAR 6 2013 .SHORT TERM...TO0DAY THROUGH FRIDAY 328 AM CST WED MAR 6 2013 FORECAST CONCERNS ARE ON FOG/FREEZING FOG POTENTIAL TONIGHT INTO THURSDAY MORNING AND TEMPERATURES THROUGH FRIDAY. FOCUS THEN QUICKLY TURNS TO PRECIPITATION TYPE CONCERNS THIS WEEKEND AND THE POTENTIAL FOR MODERATE TO HEAVY RAINFALL ACROSS PARTS OF THE AREA. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS SHOWED LOW PRESSURE OVER THE CENTRAL APPALACHIANS. A TROUGH WAS NOTED ALONG THE MINNESOTA/ONTARIO BORDER. AN UPPER RIDGE WAS BUILDING ACROSS THE WESTERN CONUS WITH A TROUGH MOVING ONTO THE WEST COAST. SURFACE OBSERVATIONS INDICATED A RIDGE OF HIGH PRESSURE EXTENDING FROM THE THE DAKOTAS SOUTH THROUGH THE SOUTHERN PLAINS. A SURFACE LOW WAS NOTED OVER VIRGINIA WITH AN INVERTED TROUGH EXTENDING NORTHWEST INTO FAR SOUTHEAST WISCONSIN. THE TROUGH ALONG THE MINNESOTA/ONTARIO BORDER WILL PROGRESS EAST TODAY ACROSS LAKE SUPERIOR AS THE SURFACE RIDGE EDGES EAST INTO THE UPPER MISSISSIPPI RIVER VALLEY. THE MAIN FORECAST CHALLENGE TODAY WILL BE CLOUD COVER. THERE ARE CURRENTLY PLENTY OF HOLES IN THE STRATUS LAYER OVER EASTERN MINNESOTA INTO SOUTHWEST WISCONSIN. FORECAST SOUNDINGS SHOW LOW LEVEL CLOUDS LINGERING THROUGH THE MORNING HOURS BEFORE FINALLY CLEARING LATE THIS AFTERNOON. THE FORECAST MODELS HAVE BEEN STRUGGLING WITH DEWPOINTS LATELY SO NOT SOLD ON THE CLOUDS HOLDING ON AS LONG AS THE MODELS SUGGEST. DECIDED TO GO WITH HIGHER CLOUD COVER THIS MORNING OVER THE PREVIOUS FORECAST...WITH CLEARING OCCURRING FROM WEST TO EAST DURING THE MID TO LATE AFTERNOON HOURS. THE NEXT CONCERN IS THE POTENTIAL FOR FOG/FREEZING FOG TONIGHT. FOG WOULD BE MORE FAVORABLE IF THE CLOUDS HOLD ON TODAY. SREF GUIDANCE AND FORECAST SOUNDINGS CONTINUE TO SUGGEST FOG DEVELOPMENT TONIGHT. LOOKING BACK TO THE WEST...UNDER THE SURFACE RIDGE...FOG HAS DEVELOPED. THE SREF PROBABILITIES ARE CAPTURING THIS SO FEEL THEY ARE DOING A DECENT JOB ON CAPTURING THE FOG. WILL MAINTAIN AREAS OF FOG IN THE FORECAST OVERNIGHT INTO THURSDAY MORNING. VISIBILITIES COULD BE REDUCED TO LESS THAN 1/2 MILE. ALSO...THE FOG COULD FREEZE TO OBJECTS CREATING HOAR FROST. SOME LIGHT ICING MAY OCCUR ON AREA ROADS...BUT THE RECENTLY APPLIED TREATMENT ON THE ROADS COULD REALLY LIMIT ICING POTENTIAL. PLAN ON LOWS FALLING INTO THE SINGLE DIGITS TONIGHT. FAVORED COLD SPOTS ACROSS CENTRAL INTO NORTH CENTRAL WISCONSIN WILL SEE TEMPERATURES FALL INTO THE SINGLE DIGITS BELOW ZERO. HIGH PRESSURE WILL BE IN CONTROL ACROSS THE REGION ON THURSDAY PROVIDING QUIET WEATHER. LOOK FOR MOSTLY SUNNY SKIES ON THURSDAY WITH HIGHS IN THE UPPER 20S TO LOWER 30S. SURFACE HIGH PRESSURE IS EXPECTED TO SLIDE EAST OF THE AREA ON FRIDAY AS A POTENT TROUGH DIVES INTO THE SOUTHWEST CONUS. MEANWHILE LOW PRESSURE DEVELOPS OVER EASTERN COLORADO AS A WARM FRONT LIFTS NORTH OUT OF THE CENTRAL PLAINS. TWO MAIN FEATURES TO WATCH CLOSELY ON FRIDAY...A NORTHERN STREAM TROUGH DIVING SOUTH OUT OF CENTRAL SASKATCHEWAN AND THE SOUTHWEST LOW LIFTING NORTHEAST TOWARD THE REGION. THE WARM FRONT LOOKS TO LIFT NORTH INTO SOUTHERN MINNESOTA/SOUTHERN WISCONSIN FRIDAY NIGHT INTO SATURDAY MORNING THEN LIFTING NORTH THROUGH THE DAY ON SATURDAY. THE NORTHERN STREAM WAVE AND ENERGY EJECTING OUT OF THE SOUTHWEST WILL INTERACT WITH THE FRONT BRINGING PRECIPITATION TO THE AREA. WARM AIR ALOFT WILL SURGE INTO THE UPPER MISSISSIPPI RIVER VALLEY FRIDAY NIGHT LEADING TO A MIX OF PRECIPITATION TYPES. A MIX OF FREEZING RAIN...SLEET AND SNOW IS EXPECTED FRIDAY EVENING INTO EARLY SATURDAY MORNING SWITCHING OVER TO MAINLY RAIN DURING THE DAY ON SATURDAY. SOME ICE ACCUMULATION IS POSSIBLE FRIDAY NIGHT INTO SATURDAY MORNING. A MOISTURE RICH AIRMASS MOVES INTO THE AREA DURING THE DAY ON SATURDAY WITH PRECIPITABLE WATER VALUES APPROACHING 270 PERCENT OF NORMAL. ALSO...TEMPERATURES ARE EXPECTED TO WARM INTO THE UPPER 30S TO LOWER 40S. 925/850 MB MOISTURE TRANSPORT FOCUSES INTO SOUTHERN WISCONSIN AND FAR NORTHEAST IOWA SATURDAY INTO SATURDAY NIGHT. PERIODS OF MODERATE TO HEAVY RAINFALL LOOK POSSIBLE SATURDAY INTO SATURDAY NIGHT LEADING TO LOCALIZED FLOODING AND ICE JAMS ON AREA RIVERS. FORECAST MODELS ARE JUST STARTING TO COME INTO AGREEMENT ON THIS WARMER AND WET SOLUTION SO WILL HAVE TO KEEP A CLOSE WATCH ON THE NEXT FEW RUNS. .LONG TERM...SATURDAY THROUGH TUESDAY 328 AM CST WED MAR 6 2013 06.00 MEDIUM RANGE MODELS ARE IN REASONABLE AGREEMENT SATURDAY INTO SATURDAY NIGHT BUT THEN START TO DIVERGE SUNDAY INTO EARLY MONDAY. THE ECMWF SHIFTS THE BOUNDARY SOUTHEAST AND EAST OF THE AREA AS AN UPPER LOW WRAPS UP OVER THE OHIO RIVER VALLEY. THE GFS LEANS TOWARD THIS SOLUTION BUT IT IS FASTER THAN THE ECMWF...TAKING THE LOW NORTH INTO THE EASTERN GREAT LAKES EARLY ON MONDAY. THE GEM OFFERS A DIFFERENT SOLUTION WITH THE LOW TAKING SHAPE OVER NORTHERN ILLINOIS WHICH WOULD BRING SIGNIFICANT SNOWFALL TO NORTHERN WISCONSIN THROUGH SOUTHERN/CENTRAL MINNESOTA. HAVE LEANED TOWARD A MODEL CONSENSUS BLEND APPROACH MONDAY INTO TUESDAY WITH CHANCES FOR SNOW MONDAY INTO MONDAY NIGHT ACROSS MUCH OF THE AREA. SNOW CHANCES WILL CONTINUE ACROSS NORTH CENTRAL WISCONSIN ON TUESDAY AS SHORTWAVE MOVES ACROSS NORTHERN WISCONSIN. PLAN ON TEMPERATURES COOLING SLIGHTLY EARLY NEXT WEEK WITH HIGHS FALLING INTO THE 30S AND LOWS IN THE TEENS TO LOWER 20S. && .AVIATION...THROUGH 06Z THURSDAY 1134 PM CST TUE MAR 5 2013 ALL OF THE SNOW HAS MOVED SOUTH OF THE TAF SITES WITH VFR VISIBILITIES NOW PREVAILING. CEILING HEIGHTS HAVE BEEN ALL OVER THE PLACE AS THE SURFACE TROUGH HAS WEAKENED BUT THE AREA STILL REMAINS IN A LOW LEVEL CYCLONIC FLOW. THIS HAS ALLOWED POCKETS OF VFR CEILING HEIGHTS OR EVEN CLEAR SKIES TO DEVELOP. THESE LAST FOR A COUPLE OF HOURS BEFORE RETURNING TO MVFR. MEANWHILE...KRST SITS IN AN IFR DECK AND IS THE ONLY SITE REPORTING ONE. SATELLITE SHOWS THE CLOUDS EXTENDING WELL TO THE WEST UNTIL REACHING THE RIDGE AXIS ACROSS THE DAKOTAS. MOST OF THE CEILINGS IN THIS CLOUD DECK ARE MVFR SO WILL GO WITH THIS FOR THE MOST PART. THE 06.00Z NAM CONTINUES TO KEEP THE LOW LEVEL RELATIVE HUMIDITY HIGH THROUGH WEDNESDAY UNTIL THE RIDGE AXIS MOVES OVERHEAD DURING THE LATE AFTERNOON OR EVENING. BASED ON THIS AND THE SATELLITE TRENDS...WILL HOLD ONTO THE CLOUDS THROUGH WEDNESDAY AFTERNOON. && .ARX WATCHES/WARNINGS/ADVISORIES... 328 AM CST WED MAR 6 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04
AREA FORECAST DISCUSSION...UPDATED
NWS PITTSBURGH PA
1234 AM EST FRI MAR 8 2013 .SYNOPSIS... COLD NORTHWEST FLOW WILL KEEP SCATTERED SNOW SHOWERS AND FLURRIES IN THE REGION THROUGH THE MORNING. HIGH PRESSURE WILL BRING CLEARING SKIES AND WARMER TEMPERATURES BY THIS WEEKEND. && .NEAR TERM /THROUGH TODAY/... LATEST RUC INDICATING UPPER LEVEL LOW A BIT FURTHER EAST AS IS ITS ASSOCIATED SHORTWAVE. ENHANCED SAT SHOWING TWO SEPARATE BANDS OF LIGHT SNOW SHOWERS/FLURRIES. WESTERN BAND OVER MY OHIO/N WV COUNTIES IS QUICKLY DISSIPATING AND THE BAND TO THE NORTHEAST IS DOING THE SAME. MOST OF THE SNOW FALLING TO THE WEST WAS FLURRIES WHILE THE SNOW TO THE NORTHEAST...WAS SLIGHTLY MORE SUBSTANTIAL. FORECAST SOUNDINGS ARE SHOWING THE INVERSIONS DROPPING QUICKLY AND THE OVERALL ATMOSPHERE DRYING OUT. FLOW ALOFT WILL VEER TO THE NORTH AS THE NIGHT PROGRESSES WHICH WILL LIMIT THE INFLUENCES FROM THE LAKES AND UP-SLOPING. FOR THE OVERNIGHT...WILL KEEP POPS TO THE NORTHEAST AND RIDGES...AS THESE AREAS WILL BE IN CLOSER PROXIMITY TO THE STRONG SHORTWAVE. FOR THE REST OF THE AREA WILL JUST MENTION FLURRIES. BY 12Z...UPPER LEVEL LOW WILL BE NEAR THE CHESAPEAKE BAY AND THE STRONG SHORTWAVE WILL BE RIGHT ON ITS HEELS. EXPECT ANY LINGERING SNOW SHOWERS/FLURRIES TO DISSIPATE DURING THE POST DAWN MORNING...WITH THE RIDGES EXPIRING LAST. OVERALL ATMOSPHERIC MOISTURE WILL DECREASE THIS AFTERNOON AND WAA WILL COMMENCE. INTERESTINGLY ENOUGH...THE WARMER AIR WILL MOVE DOWN FROM THE NORTHEAST ON THE BACK SIDE OF THE EXITING 50H LOW. THIS WARMER AIR WILL QUICKLY OVERTAKE AND ELIMINATE THE COLD POOL ALOFT. EXPECT TO SEE A DECREASE IN CLOUD COVER THIS AFTERNOON...HOWEVER TEMPS WILL REMAIN BELOW NORMAL. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... DRY AND COLD FRIDAY NIGHT UNDER HIGH PRESSURE. SATURDAY WILL WARM DRAMATICALLY UNDER WARM ADVECTION AS SOUTHWEST FLOW AT 850MB BRINGS TEMPERATURES OVER +5C...AND WITH LOTS OF SUNSHINE TEMPERATURES WILL SURGE INTO THE UPPER 40S NORTH AND MID 50S SOUTH. MILD SATURDAY NIGHT AND WARMER SUNDAY IN STRENGTHENING SOUTHWEST FLOW AHEAD OF AN APPROACHING COLD FRONT. 60 DEGREES MAY BE REACHABLE SUNDAY AFTERNOON IN PITTSBURGH BUT INCREASE IN CLOUDS MAY TEMPER WARMING. HAVE UNDERCUT GUIDANCE BUT STILL WELL ABOVE AVERAGE. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MODELS ARE IN GENERAL WITH SOLNS FEATURING THE APPRCH OF AN AMPLIFIED LOW PRES TROF/ASSOCIATED CDFNT LATE SUNDAY. HAVE THUS PERSISTED WITH POP ESCALATION FM CHC TO LIKELY NMBRS ON SUNDAY NGT AND MONDAY...AS WELL AS WITH EXPECTATIONS OF LOW PRES FORMING ON THE FRONTAL BOUNDARY AND LIKELY STALLING DECISIVE PASSAGE UNTIL TUESDAY. THEREAFTER...DIVERGENT SOLNS ARE EXHIBITED IN THE ECMWF AND GFS COMPARISON WITH THE ECMWF INDICATING ANOTHER AMPLIFIED ERN NORTH AMERICAN TROF...WHILE GFS FLATTENS THE FLOW. PREVIOUS FORECAST FOR MID TO LATE WEEK FAVORS THE COOLER ECMWF...AND LACK OF CONFIDENCE PRECLUDES ANY MAJOR ALTERATIONS TO THAT TIME FRAME. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... A WEAK DISTURBANCE IN THE FLOW ALOFT ROTATING AROUND COASTAL SYSTEM WILL CONTINUE TO HELP STRATO-CU HOLD IN OVERNIGHT. BEST SUPPORT FOR -SHSN WANING AS SUGGESTED BY HRRR. BACK EDGE OF BEST LOW LEVEL SUPPORT PUSHING ACROSS FORECAST AREA AT THIS TIME. AFTERWARDS WITH -8C AT 850 MB AND NW FLOW WILL CARRY -SHSN WITH 5-6SM VSBY EARLY IN THE PERIOD AND THEN DROP OUT. WILL KEEP LOWER STRATO-CU AROUND OVERNIGHT AND THEN RAISE CEILINGS IN MORNING WITH STILL BKN035. WILL SCATTERED OUT FROM SW TO NE BY FRIDAY AFTERNOON AND GO SKC FRIDAY NIGHT. NORTHWEST WINDS 5-10 KTS TONIGHT AND INCREASE THEM TO NORTHWEST 11-13KT G17KT ON FRIDAY WITH CONTINUED FAIRLY TIGHT PRESSURE GRADIENT DUE TO COASTAL SYSTEM`S SLOWNESS TO PULL AWAY. .OUTLOOK.../FRIDAY NIGHT THROUGH TUESDAY/... VFR CONDITIONS FRIDAY NIGHT THROUGH MOST OF SUNDAY AS HIGH PRESSURE DOMINANTS THE FORECAST AREA. NEXT WEATHER SYSTEM APPROACHES BY LATE SUNDAY WITH SHOWERS AND RESTRICTIONS POSSIBLE THROUGH EARLY TUESDAY. CLEARING EXPECTED LATER ON TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
244 AM CST FRI MAR 8 2013 .DISCUSSION... SIMILAR SCENARIO TONIGHT AS THE FORECAST IS HIGHLY VARIABLE BASED ON THERMAL PROFILES BELOW 70H. THE MODELS HAVE BEEN CONSISTENT IN TERMS OF THE EC THE COOLEST...AND THE NAM/WRF THE WARMEST. THE GEM/GFS ARE SOMEWHAT INBETWEEN. ALTHOUGH THE NAM/WRF REMAINS THE WARMEST AND KEEPS MOST OF THE PRECIPITATION IN THE FORM OF RAIN...THE GFS HAS COME A BIT CLOSER TO THE EC WHICH MEANS MORE OF A SLEET/SNOW SCENARIO FOR AREAS ACROSS THE N/NW FA. DUE TO THE VARIABILITY OF THE THERMAL PROFILES...WILL CONTINUE THE WINTER STORM WATCH IN THE SAME AREAS AS BEFORE. IT STILL LOOKS ALMOST CERTAIN THAT THE FAR NW FA WILL SEE THE BULK OF THE ICE/SNOW BEFORE TAPERING OFF SATURDAY EVENING. ELSEWHERE IS HIGHLY DEPENDENT ON SFC TEMPS AND WHETHER THE WARMER 85H TEMPS MATERIALIZE. BEST TIME PERIOD FOR FREEZING RAIN WILL OCCUR TOWARD MIDNIGHT TONIGHT...AS THE COMBINATION OF COOLER SFC TEMPS DURING THE NIGHT...AND EVAPORATIVE COOLING EFFECTS DURING THE ONSET OF THE PRECIPITATION. ONCE HEAVIER PRECIPITATION DEVELOPS...THE SCENARIO GETS TRICKY WITH THE POSSIBILITY OF CONVECTION AND LATENT HEAT EFFECTS WITH THE LIQUID PRECIPITATION. SNOW COVER IS ANOTHER ELEMENT WHICH COULD LEAD TO MORE FREEZING RAIN ON SURFACES...OTHER THAN STREETS/ROADWAYS WHICH WOULD BE MORE WET DUE TO CHEMICALS AND OTHER PROCESSES. THE CONVECTIVE ELEMENT IS ALSO PROBLEMATIC WHICH CAN LEAD TO BRIEF PERIODS OF SLEET OR SNOW DEPENDING UPON THE PRECIPITATION INTENSITY. ANOTHER CONCERN IS POTENTIAL AREAL FLOODING AS THE PRECIPITABLE WATER VALUES ARE NEAR 0.80 INCHES. THIS IS ROUGHLY 2 STANDARD DEVIATIONS ABOVE NORMAL FOR EARLY MARCH. THE CURRENT ESF DOES EXPLAIN THIS SCENARIO AND THE BEST LOCATION FOR HEAVY RAINFALL RATES...AND THE RAPID SNOWFALL MELT WOULD BE ACROSS SOUTH CENTRAL MINNESOTA. DUE TO MORE CONSISTENCY OF THE NORTHERN AND SOUTHERN JET STREAMS NOT PHASING WITH THE UPCOMING WEEKEND SYSTEM...WHICH WAS A POSSIBILITY EARLIER...THE SCENARIO OF A BAND OF HEAVY SNOWFALL ACROSS THE SE FA IS LESS LIKELY. THE BETTER POSSIBILITIES OF HEAVIER SNOWFALL RATES WILL OCCUR ACROSS IA/WI ON SUNDAY. NO OTHER CHGS IN THE FORECAST BEYOND THIS WEEKEND AS THE PATTERN IS LESS ACTIVE...BUT SEASONABLY COOL FOR MID MARCH. DO NOT EXPECT ANY RAPID WARM-UP UNTIL THE SNOW COVER IS GONE AND THE UPPER LEVEL FLOW BECOMES MORE SW. ..JLT.. && .AVIATION.../06Z TAF ISSUANCE/ FIRST CHANGE MADE TO 6Z TAFS WAS TO REMOVE RETURN OF MVFR CIGS THIS EVENING. RAP AND HRRR HAVE BEEN CONSISTENT ON TAKING MVFR CIGS OVER ERN NODAK DUE EAST ACROSS NRN MN...WILL BE A CLOSE CALL FOR AXN/STC...BUT CONFIDENCE IS HIGH THAT THIS STRATUS WILL REMAIN NORTH OF OTHER TERMINALS. INCREASING MOISTURE ON SE SFC WINDS HAS RESULTED IN BLOSSOMING OF MVFR BR ACROSS NRN IA/SRN MN...AND DO EXPECT SIMILAR VSBY TO IMPACT RWF...THOUGH EXPECT INCREASED WINDS TONIGHT TO KEEP VSBY NO WORSE THAN IFR. AFTER THAT...LOTS OF ACTION JAMMED INTO THE END OF THE TAF PERIOD AS A WALL OF CLOUDS AND PRECIP COMES NE INTO THE AREA ON A STRONG LLJ. GFS LOOKED TO ROBUST WITH MOISTURE OUT AHEAD OF THIS SYSTEM...SO FAVORED END OF TAFS HEAVILY TOWARD A NAM/SREF TIMING. AS FOR P-TYPE...TEMPS LOOK TO BE BELOW FREEZING AT STC/AXN...SO WENT WITH FZRA FOR THEM. RWF/MSP WILL LIKELY BE NEAR OR JUST ABOVE FREEZING. BASED ON NAM AND SREF P-TYPE PLUMES...EXPECT PREDOMINATE TYPE TO BE RA AT BOTH LOCATIONS...THOUGH LEFT A PROB30 FZRA IN AT MSP TO ACCOUNT FOR THE UNCERTAINTY. KMSP...HIGH CONFIDENCE IN FORECAST PARAMETERS THROUGH 00Z. ABOUT THE ONLY THING THAT MAY DIFFER FROM CURRENT TAF IS THE POSSIBILITY FOR SOME MVFR BR/HZ IN THE MORNING. AT THE END OF THE TAF...SOUNDINGS SAY WHATEVER FALLS AT THE FIELD WILL BE LIQUID...WITH THE KEY BEING SFC TEMP. PROBABILITIES FAVOR TEMPS BEING WARM ENOUGH FOR RA...BUT EVEN SO...4 MEMBERS OF THE SREF DO SHOW A FEW HOURS OF FZRA SAT MORNING...SO LEFT THE PROB30 GROUP FOR -FZRA TO GO WITH THE PREVAILING -RA. /OUTLOOK FOR KMSP/ SAT...IFR AND RAIN. LIFR AND -FZRA POSSIBLE IN THE MORNING. WINDS E AT 10KTS. SUN...MVFR OR LOWER WITH -SN POSSIBLE EARLY. WINDS N AT 15G25KTS. MON...VFR. LIGHT NW WINDS BECOMING S IN THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WATCH FROM THIS EVENING THROUGH SUNDAY MORNING FOR BENTON-CHIPPEWA-DOUGLAS-KANABEC-KANDIYOHI-LAC QUI PARLE- MCLEOD-MEEKER-MILLE LACS-MORRISON-POPE-REDWOOD-RENVILLE- SHERBURNE-STEARNS-STEVENS-SWIFT-TODD-WRIGHT-YELLOW MEDICINE. WI...NONE. && $$ JLT/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1135 PM CST THU MAR 7 2013 .UPDATE... 06Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION.../ISSUED 419 PM CST THU MAR 7 2013/ TONIGHT...THE MAIN FCST ISSUE OVERNIGHT WILL BE THE EXTENT OF CLOUD COVER AND ITS EFFECTS ON TEMPS AND FOG POTENTIAL. HIGH CLOUDS CURRENTLY STREAMING OVERHEAD...WITH A BANK OF STRATUS LURKING ACROSS NORTH CENTRAL SD EXTENDING INTO ND. 1000-850MB RH FROM THE NAM DEPICTS THE STRATUS PRETTY WELL...AND LEANED ON ITS FCST PRETTY HEAVILY FOR CLOUD COVER TRENDS. THE HIGH CLOUDS SHOULD PARTIALLY CLEAR OUT ACROSS W WI LATER TONIGHT LEADING TO POTENTIAL PATCHY FOG DEVELOPMENT. ANY FOG SHOULD BE FAIRLY LOCALIZED AS WINDS WILL BE STRONGER THAN LAST NIGHT KEEPING THE BL WELL-MIXED. WITH A PERSISTENT SE WIND, CLOUD COVER...AND THE BEGINNINGS OF WARM ADVECTION...LOW TEMPS WILL BE SUBSTANTIALLY WARMER THAN LAST NIGHT (MID TEENS TO LOWER 20S). FRIDAY THROUGH SUNDAY...HIGH PRES WILL SHIFT WELL E OF THE AREA DURG THE DAY ON FRI WHILE A LONGWAVE RIDGE GLIDES OVER THE AREA. THE COMBINATION OF BOTH FEATURES WILL ALLOW FOR STRONG WARMING OVER THE AREA...INCLUDING HIGHS REACHING THE MIDDLE AND UPPER 30S DESPITE AN INCREASE IN CLOUD COVER. THE MOST IMPORTANT ASPECT WILL BE THE MELTING OF THE SNOWPACK...ALLOWING FOR SIGNIFICANT RUNOFF AND MAKING FOR THE POTENTIAL OF REFREEZING FRIDAY NIGHT FOR LOCATIONS THAT DROP BACK TO THE FREEZING MARK. AS FOR SENSIBLE WX FRI NIGHT THRU SUN...THE LONGWAVE RIDGE AXIS WILL SHIFT TO THE E FRI NIGHT WHILE A LARGE TROUGH DIGS INTO THE SOUTHWEST. AN AREA OF LOW PRES DEVELOPING OVER THE CENTRAL ROCKIES WILL BECOME PICKED UP BY THE LARGE TROUGH...NUDGING IT INTO THE CENTRAL PLAINS SAT THEN INTO THE GREAT LAKES ON SUN. DEEP MOISTURE WILL STEADILY SPREAD NE INTO THE REGION FRI EVE ALONG THE WMFNT OF THE ROCKIES LOW PRES CENTER. SIGNIFICANT LIFT FROM NOT ONLY THE FNT BUT A MIDLVL SHTWV TROUGH AXIS SWINGING THRU THE NRN PLAINS WILL AID IN PRECIP SPREADING W TO E ACRS THE WFO MPX CWFA FRI NIGHT. COMPLICATING MATTER IS THE DEPTH OF SHALLOW WARM AIR IN THE BLYR THAT WILL MESS WITH THE P-TYPE FCST. BUFKIT SOUNDINGS AND SREF PROGS INDICATE A MIX OF -FZRA/-SN FOR MUCH OF THE NIGHT CAN BE EXPECTED... PARTICULARLY OVER WRN INTO CENTRAL MN. AS THE PRECIP SPREADS FURTHER E...INTENSITY IS EXPECTED TO INCRS AS PWATS CLIMB TO ARND 1 INCH FRI NIGHT INTO MIDDAY SAT. HOWEVER...P-TYPE IS EXPECTED TO MIX WITH AND CHANGE OVER TO RAIN FOR MUCH OF THE AREA AS TEMPS RISE TO THE MID 30S ON SAT. THE CDFNT OF THIS SYSTEM WILL THEN APPROACH LATE SAT NIGHT INTO EARLY SUN MRNG...FORCING THE CHANGE OF THE P-TYPE FROM RAIN /OR POSSIBLY A SMALL WINDOW OF -FZRA/ OVER TO -SN SAT NIGHT INTO SUN MRNG. WITH STILL DEEP MOISTURE IN PLACE...SOME MINOR TO MODERATE SNOW ACCUMULATIONS APPEAR LIKELY. THE SNOWFALL WILL THEN GRADUALLY TAPER OFF DURG THE DAY ON SUN FROM W TO E AS TEMPERATURES ARE EXPECTED TO REMAIN NEAR TO BELOW FREEZING LATE SAT NIGHT THRU SUN NIGHT. THERE IS STILL MUCH UNCERTAINTY IN TEMPERATURE PROFILES ALONG WITH THE PLACEMENT OF THE DEEPEST MOISTURE...BUT THERE IS ENOUGH MODEL AGREEMENT SUCH THAT THE HEAVIEST ICING /BETWEEN A TENTH AND A QUARTER INCH/ ALONG WITH THE HEAVIEST SNOWFALL /BETWEEN 3 AND 6 INCHES/ SUCH THAT CONFIDENCE IS HIGH ENOUGH TO ISSUE A WINTER STORM WATCH FOR PORTIONS OF WEST CENTRAL AND CENTRAL MINNESOTA STARTING FRIDAY NIGHT. EVEN THOUGH THE WATCH IS IN PLACE...ADVISORY-LEVEL ICING AND/OR SNOWFALL LOOKS POSSIBLE JUST EAST OF WHERE THE WATCH IS CURRENTLY DELINEATED SO ADDITIONAL SUPPLEMENTAL PRODUCTS MAY BE ISSUED DURING LATER PRODUCT PACKAGES TO ADDRESS THESE ISSUES. HIGH PRESSURE THEN COMES IN SUNDAY EVENING AND SUNDAY NIGHT WHICH WILL HELP CLEAR AWAY ANY REMAINING PRECIP...PRODUCE PARTIAL CLEARING SKIES AND PROMOTE COLD AIR ADVECTION THAT WILL MAKE FOR LOW TEMPS SUN NIGHT DROPPING BACK INTO THE SINGLE DIGITS TO MID TEENS. MONDAY THROUGH WEDNESDAY...HIGH PRES LOOKS TO PREVAIL ON MON AS A SHORTWAVE BUBBLE RIDGE LOOKS TO GLIDE ON THROUGH THE REGION. HOWEVER...A PROGRESSIVE WNW-ESE FLOW WILL DEVELOP TUE AND WED THAT WILL ALLOW A PAIR OF SHALLOW CLIPPER-TYPE LOW PRESSURE SYSTEMS TO SHIFT ON THROUGH THE REGION. NEITHER LOOKS PARTICULARLY STRONG NOR MOISTURE-LADEN SO HAVE KEPT ONLY SLGT-LOW CHC POPS IN PLACE. TEMPERATURES WILL DROP BACK TO BELOW NORMAL LEVELS DURING THE FIRST HALF OF NEXT WEEK. && .AVIATION.../06Z TAF ISSUANCE/ FIRST CHANGE MADE TO 6Z TAFS WAS TO REMOVE RETURN OF MVFR CIGS THIS EVENING. RAP AND HRRR HAVE BEEN CONSISTENT ON TAKING MVFR CIGS OVER ERN NODAK DUE EAST ACROSS NRN MN...WILL BE A CLOSE CALL FOR AXN/STC...BUT CONFIDENCE IS HIGH THAT THIS STRATUS WILL REMAIN NORTH OF OTHER TERMINALS. INCREASING MOISTURE ON SE SFC WINDS HAS RESULTED IN BLOSSOMING OF MVFR BR ACROSS NRN IA/SRN MN...AND DO EXPECT SIMILAR VSBY TO IMPACT RWF...THOUGH EXPECT INCREASED WINDS TONIGHT TO KEEP VSBY NO WORSE THAN IFR. AFTER THAT...LOTS OF ACTION JAMMED INTO THE END OF THE TAF PERIOD AS A WALL OF CLOUDS AND PRECIP COMES NE INTO THE AREA ON A STRONG LLJ. GFS LOOKED TO ROBUST WITH MOISTURE OUT AHEAD OF THIS SYSTEM...SO FAVORED END OF TAFS HEAVILY TOWARD A NAM/SREF TIMING. AS FOR P-TYPE...TEMPS LOOK TO BE BELOW FREEZING AT STC/AXN...SO WENT WITH FZRA FOR THEM. RWF/MSP WILL LIKELY BE NEAR OR JUST ABOVE FREEZING. BASED ON NAM AND SREF P-TYPE PLUMES...EXPECT PREDOMINATE TYPE TO BE RA AT BOTH LOCATIONS...THOUGH LEFT A PROB30 FZRA IN AT MSP TO ACCOUNT FOR THE UNCERTAINTY. KMSP...HIGH CONFIDENCE IN FORECAST PARAMETERS THROUGH 00Z. ABOUT THE ONLY THING THAT MAY DIFFER FROM CURRENT TAF IS THE POSSIBILITY FOR SOME MVFR BR/HZ IN THE MORNING. AT THE END OF THE TAF...SOUNDINGS SAY WHATEVER FALLS AT THE FIELD WILL BE LIQUID...WITH THE KEY BEING SFC TEMP. PROBABILITIES FAVOR TEMPS BEING WARM ENOUGH FOR RA...BUT EVEN SO...4 MEMBERS OF THE SREF DO SHOW A FEW HOURS OF FZRA SAT MORNING...SO LEFT THE PROB30 GROUP FOR -FZRA TO GO WITH THE PREVAILING -RA. /OUTLOOK FOR KMSP/ SAT...IFR AND RAIN. LIFR AND -FZRA POSSIBLE IN THE MORNING. WINDS E AT 10KTS. SUN...MVFR OR LOWER WITH -SN POSSIBLE EARLY. WINDS N AT 15G25KTS. MON...VFR. LIGHT NW WINDS BECOMING S IN THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SUNDAY MORNING FOR BENTON-CHIPPEWA-DOUGLAS-KANABEC-KANDIYOHI-LAC QUI PARLE- MCLEOD-MEEKER-MILLE LACS-MORRISON-POPE-REDWOOD-RENVILLE- SHERBURNE-STEARNS-STEVENS-SWIFT-TODD-WRIGHT-YELLOW MEDICINE. WI...NONE. && $$ JPC/MPG
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
1239 AM EST FRI MAR 8 2013 .SYNOPSIS... COOL AND DRY CANADIAN HIGH PRESSURE WILL REMAIN OVER THE REGION INTO THE WEEKEND. A COLD FRONT WILL MOVE ACROSS THE REGION LATE MONDAY REACHING THE COAST BY TUESDAY. ANOTHER DRY HIGH WILL MOVE INTO THE AREA FOR MID WEEK. && .NEAR TERM /THROUGH TODAY/... AS OF 1235 AM...WINDS HAVE REMAINED UP OUTSIDE OF THE MTNS AND GUSTY OVER THE MTNS. EXPECT THE WINDS TO CONTINUE UNTIL NEAR DAYBREAK WHEN THEY DIMINISH. LINGERING LOW CLOUDS WILL REMAIN NEAR THE TN BORDER BUT BEGIN DISSIPATING FROM THE SW NEAR DAYBREAK. AS OF 1035 PM EST THU...BLENDED IN SOME RUC13 WINDS WHICH HAS BUMPED UP THE SPEEDS A LITTLE OVER THE NRN PART OF THE UPSTATE AND THE SRN NC PIEDMONT. WINDS ARE RUNNING AROUND 10 KTS IN THESE AREAS ATTM. OTHERWISE THE SKY GRIDS WERE AGAIN TWEAKED TO CAPTURE THE CURRENT ORIENTATION OF THE STRATO-CU ALONG THE TN LINE. IT/S MADE SOME PROGRESS UP THE FRENCH BROAD AND PIGEON RIVER VALLEYS...THOUGH I DON/T SEE IT GETTING MUCH FURTHER SOUTH. TEMPERATURES WERE LOWERED AGAIN OVER THE NRN NC FOOTHILLS. AS OF 755 PM EST THU...ADDED A LITTLE MORE CLOUD COVER RIGHT ALONG THE TN LINE. ALSO LOWERED HOURLY TEMPS A FEW DEGREES OVER THE NRN MTNS AND NC FOOTHILLS WHERE TEMPS ARE RUNNING LOWER THAN PREDICTED. THE REST OF THE GRIDS LOOK TO BE IN GOOD SHAPE. AS OF 510 PM EST THU...UPDATED SKY GRIDS TO ACCOUNT FOR SHARP CLEARING LINE ALONG THE TN LINE. UPSTREAM STRATUS HAS BEEN VERY PERSISTENT AND I HAVE IT HOLDING ON RIGHT ALONG THE LINE FOR SEVERAL MORE HOURS. THE OTHER 98 PERCENT OF THE FORECAST AREA WILL HAVE A LOVELY EVENING. TEMPERATURES WERE ALSO ADJUSTED DOWN A FEW DEGREES OVER THE CENTRAL AND NRN MTNS...MAINLY AS A RESULT OF SNOW COVER. PREVIOUS DISCUSSION... THE REGION WILL REMAIN UPSTREAM OF A LONG WAVE TROUGH OFF THE EAST COAST...WITH HIGH AMPLITUDE RIDGING TO THE WEST THROUGH THE PERIOD. THIS WILL SUPPORT A RIDGE OF SURFACE HIGH PRESSURE ACROSS THE REGION. SOME DEGREE OF LOW LEVEL MOISTURE WILL CONTINUE TO SUPPORT UPSLOPE STRATOCU ALONG THE IMMEDIATE TENN BORDER...AND THIS MAY EVEN EXPAND A BIT TONIGHT. OTHER THAN THAT...FAIRLY GOOD RADIATIONAL COOLING CONDITIONS ARE EXPECTED TONIGHT...WHICH SHOULD ALLOW MIN TEMPS TO COOL TO ABOUT 10 DEGREES BELOW NORMAL. FRIDAY...THE WESTERN ATLANTIC TROUGH RECEIVES SOME REINFORCEMENT... AS A POTENT SHORT WAVE DIGS OFF THE MID-ATLANTIC COAST. THIS WILL SUPPORT CONTINUED LOW THICKNESS VALUES ACROSS OUR AREA...AND MAX TEMPS WILL BE ONLY MARGINALLY DIFFERENT THAN TODAY/S READINGS. && .SHORT TERM /TONIGHT THROUGH SUNDAY/... AS OF 145 PM THURSDAY...AN UPPER LEVEL RIDGE WILL DOMINATE THE WEATHER THROUGH THE UPCOMING WEEKEND PROVIDING VERY PLEASANT AND DRY WEATHER. THE RIDGE AXIS IS FORECAST TO MOVE EAST OF THE APPALACHIANS BY 12Z SUNDAY. AT THE SFC...A NORTH TO SOUTH ORIENTED HIGH PRESSURE SYSTEM WILL MOVE FROM THE MID WEST FRIDAY NIGHT...TO OFF THE EAST COAST ON SUNDAY. THIS WILL RESULT IN MOSTLY CLEAR CONDITIONS THROUGH SAT NIGHT. THE RETURN FLOW ON THE WESTERN PERIPHERY OF THE HIGH WILL TRANSPORT INCREASING ATLANTIC MOISTURE INTO THE AREA BEGINNING SAT NIGHT AND CONTINUING ON SUN. THEREFORE...EXPECT INCREASING AMOUNTS OF CLOUDS FROM LATE SATURDAY NIGHT INTO SUNDAY. RIDGING ALOFT AND WARMING LOW LEVEL THICKNESSES SHOULD RESULT IN ABOVE NORMAL HIGHS BOTH SATURDAY AND SUNDAY. MAX TEMPS SHOULD REACH THE MID 60S OUTSIDE THE MOUTNAINS...WITH EVEN LOW 60S MOUNTAIN VALLEYS. GOOD RADIATIONAL COOLING FRI NIGHT WILL ALLOW MIN TEMPS TO COOL AROUND 5 DEGREES BELOW NORMAL...BUT NEAR TO A LITTLE ABOVE NORMAL TEMPS SHOULD OCCUR SAT NIGHT AS MOISTURE INCREASES. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 145 PM EST THURSDAY...07/12Z GFS AND 07/00Z ECM ARE IN FAIRLY GOOD AGREEMENT IN REGARD TO THE PERTINENT WEATHER FEATURES THROUGH THE MEDIUM RANGE. THE 07/12Z CANADIAN CAME IN AS AN OUTLIER AND WAS DISREGARDED FOR THIS FORECAST. AN UPPER RIDGE WILL BE MOVING EAST OF THE AREA AT THE BEGINNING OF THE PERIOD WITH A SHORT WAVE TROUGH OVER THE MIDWEST. THE UPPER TROUGH IS FORECAST TO MOVE EAST AND TRAVERSE THE REGION MONDAY NIGHT INTO TUE. THE TROUGH WILL DRIVE A SURFACE COLD FRONT THROUGH THE AREA. MODEL TIMING FOR THE COLD FRONTAL PASSAGE IS CONVERGING ON MON NIGHT INTO EARLY TUE. AS SURFACE HIGH PRESSURE MOVES EAST OF THE AREA SUNDAY NIGHT AND MON...THE RETURN FLOW WILL TAP INTO ATLANTIC/GULF MOISTURE OUT AHEAD OF THE COLD FRONT. A FEW SHOWERS COULD DEVELOP OVER WESTERN UPSLOPE AREAS BY EARLY MON. SHOWERS ARE THEN EXPECTED TO SLOWLY EVERSPREAD MOST OF THE AREA ON MONDAY FROM WEST TO EAST. THE COLD FRONT WILL CROSS THE AREA MONDAY NIGHT INTO EARLY TUE. MODERATE AMOUNTS OF RAINFALL ARE EXPECTED ACROSS THE REGION...MOST LIKELY IN THE HALF INCH TO INCH RANGE. WITH THE FRONTAL PASSAGE OCCURRING DURING THE NIGHT...INSTABILITY WILL BE LIMITED SO DO NOT HAVE ANY THUNDER MENTIONED. ALSO...TEMPERATURES SHOULD BE MILD ENOUGH SO THAT NO PTYPE ISSUES AREA EXPECTED. THE ONLY EXECEPTION MAY THE ELEVATIONS ABOVE 3500FT IN THE WAKE OF THE FRONT WHERE THERE COULD BE A BRIEF PERIOD OF SNOW MIXED WITH RAIN. BEHIND THE FRONT...DRYING NW FLOW SHOULD COMMENCE SO CLEARING SHOULD OCCUR WEST TO EAST ACROSS THE AREA ON TUE. HIGH PRESSURE WILL BUILD TOWARD THE AREA ON WED/THU. 12Z GFS TIME/HEIGHTS SUGGEST LOW LEVEL MOISTURE MAY BE SUFFICENT FOR MORE CLOUDS ON WED/THU BUT WILL STAY CLOSER TO THE DRYER ECM SOLUTION AND FORECAST MOSTLY CLEAR/CLEAR SKY CONDITIONS. TEMPS WILL BEGIN THE PERIOD A LITTLE ABOVE AVERAGE AND THEN COOL SLIGHTLY BELOW NORMAL BY THE END OF THE PERIOD. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AT KCLT AND ELSEWHERE...CLEAR SKIES THROUGH THE PERIOD. N TO NE WINDS EARLY THIS MORNING WILL STRENGTHEN WITH MIXING AFTER DAYBREAK. IN FACT...LOW END GUSTS ARE LIKELY AT KCLT AND POSSIBLE AT KHKY. WINDS BECOME NLY AT KGSP/KGMU FOR THE AFTERNOON AND LIGHT WSW AT KAND WITH WEAK LEE TROF DEVELOPING. LIGHT N TO NE WINDS DEVELOP DURING THE EVENING. AT KAVL...GUSTY NNW WINDS WILL PERSIST TO NEAR DAYBREAK WHEN GUSTS DIMINISH. GUST RETURN WITH MIXING AFTER DAYBREAK WITH LIGHT WINDS DEVELOPING DURING THE EVENING. DO NOT EXPECT THE LOW CLOUDS NEAR THE TN BORDER TO REACH THE AIRPORT. OUTLOOK...DRY HIGH PRESSURE WILL PERSIST THROUGH THE WEEKEND. MOISTURE AND RESTRICTIONS SHOULD RETURN BY LATE MONDAY AHEAD OF THE NEXT APPROACHING COLD FRONT. CONFIDENCE TABLE... 05-11Z 11-17Z 17-23Z 23-05Z KCLT HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGSP HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAVL MED 78% HIGH 99% HIGH 100% HIGH 100% KHKY HIGH 100% HIGH 100% HIGH 100% HIGH 100% KGMU HIGH 100% HIGH 100% HIGH 100% HIGH 100% KAND HIGH 100% HIGH 100% HIGH 100% HIGH 100% THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE) WWW.WEATHER.GOV/GSP/AVIATION_TABLES && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...PAT NEAR TERM...JDL/MCAVOY/RWH SHORT TERM...LG LONG TERM...LG AVIATION...RWH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
305 AM CST FRI MAR 8 2013 .SHORT TERM...TODAY THROUGH SUNDAY NIGHT 305 AM CST FRI MAR 8 2013 MAIN FORECAST CONCERN IS ON PRECIPITATION TYPES LATE TONIGHT INTO EARLY SATURDAY AND THEN AGAIN ON SUNDAY. ALSO OF CONCERN IS FLOODING POTENTIAL WITH THE RAIN ON SATURDAY AND SATURDAY NIGHT. 07Z SURFACE ANALYSIS SHOWS RIDGE AXIS OVER EASTERN WISCONSIN SOUTHWARD INTO EASTERN ILLINOIS. INFRARED SATELLITE IMAGERY JUST SHOWING A FEW HIGH CLOUDS OVER IOWA AND ILLINOIS...WITH SOME PATCHY STRATUS OVER NORTHWEST WISCONSIN. A LARGER STRATUS FIELD IS FOUND OVER NORTH DAKOTA INTO NORTHWEST MINNESOTA. 08.00Z DETERMINISTIC MODELS OFFER SIMILAR SOLUTIONS THROUGH THE PERIOD...WITH THE BIGGEST DIFFERENCES ON PRECIPITATION ONSET FRIDAY NIGHT. GFS THE FASTEST OF ALL THE SOLUTIONS...WITH A NICE CLUSTERING OF THE NAM/GEM AND ECMWF ALL SHOWING A SLOWER ONSET AND THUS DID GO WITH THE SLOWER SOLUTIONS. THE HIGH WILL CONTINUE TO SHIFT EASTWARD TODAY INTO THE GREAT LAKES. MID AND HIGH LEVEL MOISTURE WILL BEGIN TO SPREAD INTO THE AREA LATER THIS AFTERNOON. HOWEVER...850MB-700MB WARM ADVECTION ALONG WITH SOME SUNSHINE WILL PUSH TEMPERATURES INTO THE 35 TO 40 DEGREE RANGE FOR MOST OF THE AREA. ATTENTION THEN TURNS TO LONGWAVE TROUGH MIGRATING EASTWARD OUT OF THE WESTERN CONUS. SURFACE CYCLOGENESIS OCCURS TONIGHT...WITH MOISTURE STREAMING NORTHWARD AHEAD OF IT. NOSE OF THE MOISTURE TRANSPORT PUSHES INTO NORTHERN IOWA AND SOUTHEAST MINNESOTA THIS EVENING AS WARM FRONT LIFTS INTO IOWA...THEN INTO THE FORECAST AREA SATURDAY. EXPECT PRECIPITATION TO BREAK OUT ACROSS IOWA AND MINNESOTA DURING THE EVENING AND THEN PUSH EASTWARD SPREADING ACROSS MUCH OF THE REMAINDER OF THE AREA BETWEEN 06Z-12Z SATURDAY. THERMAL PROFILES CONTINUE TO INDICATE A WINTRY MIX INITIALLY AS SURFACE TEMPERATURES WILL BE AT OR SLIGHTLY BELOW THE FREEZING MARK WHEN THE PRECIPITATION BEGINS. NOT EXPECTING ANY MAJOR ICING AS LOW LEVEL WARMING CONTINUES IN WARM ADVECTION REGIME AND EXPECT A TRANSITION THEN TO ALL RAIN BY MID MORNING SATURDAY. THUS EXPECTING LESS THAN A TENTH OF AN INCH OF ICE. THERE IS SOME CONCERN THAT TEMPERATURES MAY EVEN STAY ABOVE FREEZING AS THE MAIN COLD FRONT REMAINS WELL WEST OF THE AREA. LATER SHIFTS WILL HAVE TO MONITOR FOR POSSIBLE ADVISORY FROM LATE TONIGHT THROUGH EARLY SATURDAY MORNING. TEMPERATURES ALOFT ARE EXPECTED TO RISE TO NEAR +6 DEGREES CELSIUS ON SATURDAY...WITH CONTINUED LOW LEVEL WARMING INTO THE UPPER 30S TO AROUND 40 AT THE SURFACE. THUS A TRANSITION TO ALL RAIN EXPECTED WHICH LEADS TO ANOTHER POTENTIAL PROBLEM OF RAIN ON TOP OF THE HEAVY SNOW PACK. MODELS HAVE BEEN CONSISTENT IN DROPPING BETWEEN 1/2 AND 1 INCH OF LIQUID PRECIPITATION THROUGH SATURDAY NIGHT. THIS MODERATE RAINFALL ON THE SNOWPACK COULD LEAD TO SOME FLOODING CONCERNS (SEE HYDROLOGY SECTION BELOW FOR MORE DETAILS). LATEST MODELS LOOK OP PUSH THE COLDER AIR IN A LITTLE QUICKER ON SUNDAY THAN PREVIOUS RUNS WITH MODELS HINTING AT A DEFORMATION BAND SITTING UP ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA. THUS EXPECT RAIN TO TRANSITION TO SNOW AND COULD SEE UP TO AN INCH OF ACCUMULATION IN AREAS NORTHWEST OF A ROCHESTER MINNESOTA TO NEILLSVILLE WISCONSIN LINE. WILL HAVE TO WATCH THIS BAND AND HOW QUICKLY THE RAIN CHANGES TO SNOW AS A LITTLE MORE IN ACCUMULATION COULD BE POSSIBLE. HIGH PRESSURE THEN BEGINS TO BUILD INTO THE AREA SUNDAY NIGHT AS THE SURFACE LOW LIFTS NORTHEAST AWAY FROM THE AREA WITH CLEARING SKIES. .LONG TERM...MONDAY THROUGH THURSDAY 305 AM CST FRI MAR 8 2013 RATHER PROGRESSIVE FLOW EXPECTED DURING THIS PERIOD. 08.00Z GFS MORE ZONAL THAN THE 08.00Z ECMWF AS THE ECMWF KEEPS A CLOSED 500MB LOW JUST NORTH OF LAKE SUPERIOR AT THE BEGINNING OF THE PERIOD THEN PUSHING IT SLOWLY EASTWARD WITH TIME. IN EITHER CASE...WEAK WAVES IN THE FLOW LIKELY TO TRACK ACROSS THE AREA...WITH A LOW PROBABILITY OF PRECIPITATION TUESDAY AND WEDNESDAY. BELOW NORMAL TEMPERATURES EXPECTED MONDAY...BUT WILL RISE TO NEAR NORMAL TUESDAY THROUGH THURSDAY...WHICH GENERALLY RANGES FROM 35 TO 40 ACROSS THE AREA. DEPENDING ON TIMING OF PRECIPITATION...IT WOULD LIKELY BE IN THE FORM OF RAIN DURING THE DAY AND SNOW AT NIGHT. && .AVIATION...THROUGH 06Z SATURDAY 1127 PM CST THU MAR 7 2013 STILL SOME CONCERN THAT FOG WILL FORM OVERNIGHT DROPPING THE VISIBILITY TO MVFR. THE 08.00Z NAM AND 08.03Z RAP HAVE BACKED OFF THE IDEA THAT SATURATION WILL OCCUR AT KLSE AND WITH A 6 DEGREE TEMP/DEW POINT SPREAD...THIS SEEMS REASONABLE. WILL NOT TOTALLY DROP THE MENTION OF FOG AT KLSE BUT JUST HAVE IT IN A TEMPO GROUP FOR LATE TONIGHT. THE SAME SCENARIO IS SHOW FOR KRST BUT THE VISIBILITY HAS BEEN SLOWLY DROPPING THERE...SO CONFIDENCE IS NOT AS HIGH THAT THE MODELS ARE CORRECT. WITH THE VISIBILITY ALREADY GOING DOWN WILL CONTINUE TO SHOW SOME MVFR FOG DEVELOPING AND LASTING THROUGH THE MIDDLE OF FRIDAY MORNING. ONCE THE FOG IS GONE...VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE NIGHT. THE NEXT SYSTEM TO IMPACT THE AREA IS STILL OFF THE CALIFORNIA COAST THIS EVENING. THE NAM CONTINUES TO BE A SLOWER SOLUTION BRINGING THIS SYSTEM IN AND HOLDS THE PRECIPITATION BACK UNTIL WELL AFTER 09.06Z WHILE THE 08.00Z GFS WOULD HAVE PRECIPITATION FALLING AT BOTH TAF SITES BY 09.06Z. THE 07.12Z ECMWF IS BETWEEN THESE TWO SOLUTIONS BUT HOLDS THE PRECIPITATION BACK UNTIL AFTER 09.06Z AS WELL. GIVEN THAT THE SYSTEM IS STILL OFF THE COAST AND THAT THE MODELS TEND TO BE TOO FAST WITH SOUTHWEST FLOW SYSTEMS...WILL NOT INTRODUCE ANY PRECIPITATION AT THIS TIME. && .HYDROLOGY...TONIGHT THROUGH SUNDAY 305 PM CST THU MAR 7 2013 RAINFALL AND SNOWMELT FRIDAY NIGHT THROUGH SATURDAY NIGHT MAY LEAD TO RUNOFF ISSUES INTO AREA CREEKS AND RIVERS. CURRENTLY EXPECTING ANYWHERE FROM 1/2 TO 1 INCH OF LIQUID TO FALL ONTO THE SNOWPACK IN PLACE. DUE TO THE DEEPER SNOWPACK...MUCH OF THIS RAINFALL CAN BE ABSORBED. HOWEVER...IF RAINFALL BECOMES HEAVIER OR MORE SNOWMELT THAN ANTICIPATED OCCURS...RUNOFF MAY BECOME AN ISSUE...ESPECIALLY GIVEN THE FACT THAT THE TOP LAYER OF GROUND IS SOLID WITH CONCRETE FROST. WILL BE ISSUING A HYDROLOGIC OUTLOOK PRODUCT TO COVER THIS INCREASING CONCERN. && .ARX WATCHES/WARNINGS/ADVISORIES... 305 AM CST FRI MAR 8 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...RABERDING LONG TERM...RABERDING AVIATION...04 HYDROLOGY...DAS/JLR
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1127 PM CST THU MAR 7 2013 .SHORT TERM...TONIGHT THROUGH SUNDAY 213 PM CST THU MAR 7 2013 MAIN CONCERN FOCUSED ON STORM SYSTEM AFFECTING THE AREA FRIDAY NIGHT THROUGH SUNDAY WITH A WINTRY MIX AND SIGNIFICANT RAINFALL. WATER VAPOR THIS AFTERNOON SHOWS A BROAD MID-LEVEL TO SURFACE RIDGE OF HIGH PRESSURE ACROSS THE CENTRAL CONUS INCLUDING THE UPPER MISSISSIPPI RIVER REGION. SOME LINGERING STRATOCUMULUS TRAPPED UNDER THE SUBSIDENCE INVERSION WERE NOTED JUST SOUTH OF THE AREA OVER EASTERN IA/NORTHERN IL...OTHER THAN THAT...JUST SOME OCCASIONAL CIRRUS WAS DRIFTING OVER THE FORECAST AREA WITH TEMPERATURES AS OF 2 PM IN THE UPPER 20S TO THE MIDDLE 30S. 07.12Z MODELS COMING INTO VERY GOOD AGREEMENT THROUGH THE SHORT TERM...LENDING TO HIGHER OVERALL FORECAST CONFIDENCE. LOOK FOR THE SURFACE RIDGE OF HIGH PRESSURE TO SLIP EAST INTO THE GREAT LAKES REGION OVERNIGHT. THIS WILL TURN WINDS TO A SOUTHEASTERLY DIRECTION IN THE 5 TO 10KT RANGE. MOSTLY CLEAR/PARTLY CLOUDY SKIES AND VERY LIGHT WINDS INITIALLY TONIGHT ACROSS THE EAST EXPECTED TO ALLOW TEMPERATURES TO FALL OFF PRETTY GOOD. EXPECTING LOWS FOR AREAS ALONG/NORTHEAST IF I-94 IN THE SINGLE DIGITS ABOVE ZERO IN THE FAVORED COLD LOWER-LYING SPOTS. ELSEWHERE ACROSS THE AREA...EXPECTING LOWS IN THE TEENS. QUIET CONDITIONS EXPECTED INTO FRIDAY. WILL HAVE TO WATCH CLOUD TRENDS THOUGH AS MODEL SOUNDINGS/NAM BUFR INDICATING AN INCREASE IN STRATUS AS WARMING TAKES PLACE OVER THE SNOWPACK IN PLACE. HAVE ADJUSTED CLOUD GRIDS ACCORDINGLY TO REFLECT THIS. FOCUS THEN SHIFTS TO THE STORM AFFECTING THE STORM SYSTEM AFFECTING THE AREA FRIDAY NIGHT THROUGH SUNDAY. AS STATED ABOVE...LATEST RUN OF THE MODELS SHOWING VERY GOOD AGREEMENT ON A GOOD SLUG OF MOISTURE MOVING INTO THE AREA FRIDAY NIGHT AND BECOMING HEAVIEST DURING THE DAY SATURDAY INTO SATURDAY EVENING AHEAD OF LOW PRESSURE MOVING OUT OF THE CENTRAL PLAINS. WILL HAVE TO DEAL WITH 2 FACETS OF THIS STORM. THE FIRST WILL BE PRECIPITATION TYPES AT ONSET FRIDAY NIGHT LASTING INTO SATURDAY MORNING. VERTICAL THERMAL PROFILES DEPICTED BY THE MODELS CONTINUE TO SUPPORT A WINTRY MIX OF FREEZING RAIN/RAIN/SLEET FOR THE AREA. THEN...LOOK FOR A TRANSITION IN THE PRECIPITATION TO ALL RAIN DURING THE DAY SATURDAY AS TEMPERATURES ALOFT WARM TO AROUND 8C WITH LOWER BOUNDARY LAYER TEMPERATURES TRENDING UPWARD AS WELL. THE SECOND FACET OF THIS STORM WILL BE MODERATE RAINFALL EXPECTED THROUGH THE REMAINDER OF SATURDAY INTO SATURDAY EVENING. PRECIPITABLE WATER VALUES CLIMB INTO THE 250-300 PERCENT ABOVE NORMAL RANGE... CORRESPONDING TO 0.75-1.00 INCH RANGE. CONCERNS ARISE AS FAR AS RUNOFF BECOMING AN ISSUE. SEE HYDROLOGY DISCUSSION BELOW FOR DETAILS. WITH ALL THIS IN MIND...WILL LIKELY HAVE TO ISSUE A WINTER WEATHER ADVISORY FOR FRIDAY NIGHT INTO SATURDAY MORNING FOR THE WINTRY MIX GIVEN THE POTENTIAL FOR SOME ICING OF AROUND A TENTH OF AN INCH. WILL PASS THIS ONTO THE MIDSHIFT TO ASSESS WITH LATEST AVAILABLE MODEL DATA. ANOTHER CONCERN TO CONTEND WITH WILL BE FOG POTENTIAL FRIDAY NIGHT THROUGH SATURDAY NIGHT WITH LOWER BOUNDARY LAYER BECOMING SATURATED AND LIGHT WINDS OVER THE MELTING SNOWPACK. EXPECTING THE PRECIPITATION TO SLOWLY TRANSITION OVER TO SNOW FROM NORTHWEST TO SOUTHEAST SATURDAY NIGHT...THEN SLOWLY TAPERING OFF SUNDAY AS THE LOW PULLS INTO SOUTHERN ONTARIO. PERHAPS 1-2 INCHES OF SNOW ACCUMULATION MAY BEE SEEN NORTHWEST OF A LINE FROM BLACK RIVER FALLS WI TO AUSTIN MN. .LONG TERM...MONDAY THROUGH THURSDAY 213 PM CST THU MAR 7 2013 07.12Z MEDIUM RANGE MODELS SHOWING SOME DIFFERENCES IN THE LONG TERM PERIOD. THE GFS IS TRENDING TOWARD A MORE HIGH-ZONAL FLOW ACROSS THE CONUS WHEREAS THE ECMWF WHICH SEEMS TO HAVE MORE RUN-TO-RUN CONSISTENCY MAINTAINS A NORTHWEST FLOW INTO THE AREA. HAVE TAKEN A BLEND APPROACH AT THIS POINT AND CARRIED A SLIGHT CHANCE OF RAIN/SNOW MIX ON TUESDAY AS A WEAK LOW MOVES SOUTHEAST THROUGH CANADA INTO THE GREAT LAKE REGION. THE REST OF THE PERIOD LOOKS DRY AT THIS TIME. TEMPERATURES THROUGH THE PERIOD LOOK TO BE RIGHT AROUND NORMAL WITH HIGHS IN THE MID 30S TO AROUND 40. && .AVIATION...THROUGH 06Z SATURDAY 1127 PM CST THU MAR 7 2013 STILL SOME CONCERN THAT FOG WILL FORM OVERNIGHT DROPPING THE VISIBILITY TO MVFR. THE 08.00Z NAM AND 08.03Z RAP HAVE BACKED OFF THE IDEA THAT SATURATION WILL OCCUR AT KLSE AND WITH A 6 DEGREE TEMP/DEW POINT SPREAD...THIS SEEMS REASONABLE. WILL NOT TOTALLY DROP THE MENTION OF FOG AT KLSE BUT JUST HAVE IT IN A TEMPO GROUP FOR LATE TONIGHT. THE SAME SCENARIO IS SHOW FOR KRST BUT THE VISIBILITY HAS BEEN SLOWLY DROPPING THERE...SO CONFIDENCE IS NOT AS HIGH THAT THE MODELS ARE CORRECT. WITH THE VISIBILITY ALREADY GOING DOWN WILL CONTINUE TO SHOW SOME MVFR FOG DEVELOPING AND LASTING THROUGH THE MIDDLE OF FRIDAY MORNING. ONCE THE FOG IS GONE...VFR CONDITIONS EXPECTED FOR THE REMAINDER OF THE NIGHT. THE NEXT SYSTEM TO IMPACT THE AREA IS STILL OFF THE CALIFORNIA COAST THIS EVENING. THE NAM CONTINUES TO BE A SLOWER SOLUTION BRINGING THIS SYSTEM IN AND HOLDS THE PRECIPITATION BACK UNTIL WELL AFTER 09.06Z WHILE THE 08.00Z GFS WOULD HAVE PRECIPITATION FALLING AT BOTH TAF SITES BY 09.06Z. THE 07.12Z ECMWF IS BETWEEN THESE TWO SOLUTIONS BUT HOLDS THE PRECIPITATION BACK UNTIL AFTER 09.06Z AS WELL. GIVEN THAT THE SYSTEM IS STILL OFF THE COAST AND THAT THE MODELS TEND TO BE TOO FAST WITH SOUTHWEST FLOW SYSTEMS...WILL NOT INTRODUCE ANY PRECIPITATION AT THIS TIME. && .HYDROLOGY... 213 PM CST THU MAR 7 2013 RAINFALL AND SNOWMELT FRIDAY NIGHT THROUGH SATURDAY NIGHT MAY LEAD TO RUNOFF ISSUES INTO AREA CREEKS AND RIVERS. CURRENTLY EXPECTING ANYWHERE FROM 1/2 TO 1 INCH OF LIQUID TO FALL ONTO THE SNOWPACK IN PLACE. DUE TO THE DEEPER SNOWPACK...MUCH OF THIS RAINFALL CAN BE ABSORBED. HOWEVER...IF RAINFALL BECOMES HEAVIER OR MORE SNOWMELT THAN ANTICIPATED OCCURS...RUNOFF MAY BECOME AN ISSUE...ESPECIALLY GIVEN THE FACT THAT THE TOP LAYER OF GROUND IS SOLID WITH CONCRETE FROST. WILL BE ISSUING A HYDROLOGIC OUTLOOK PRODUCT TO COVER THIS INCREASING CONCERN. && .ARX WATCHES/WARNINGS/ADVISORIES... 213 PM CST THU MAR 7 2013 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...04 HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS PUEBLO CO
507 AM MST FRI MAR 8 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 506 AM MST FRI MAR 8 2013 CLOUDS ARE INCREASING OVR WRN CO THIS MORNING AHEAD OF THE UPPER LEVEL LOW THAT SATELLITE IMAGES SHOW OFF THE SRN CA COAST. A THICK BAND OF CLOUDS HAS ALSO MOVED UP OVR THE SERN CORNER OF THE STATE...BUT THAT SHOULD PUSH EAST LATER THIS MORNING. BY EVENING THE UPR LOW CENTER IS EXPECTED TO MOVE OVR THE CA AND AZ BORDER AREA. BOTH THE HRRR AND NAM12 SHOWING PCPN HOLDING OFF OVR THE SWRN MTS UNTIL AT LEAST LATE MORNING...BUT THEN WE SHOULD SEE PCPN ALL ALONG THE CONTDVD THIS AFTERNOON...WITH SCT TO LIKELY POPS SPREADING OVR MUCH OF THE ERN MTS AS WELL AND OVR THE SAN LUIS VALLEY...AND MAINLY ISOLD CHANCE FOR RAIN OVR THE SERN PLAINS. FOR THIS AFTERNOON THE NAM IS SHOWING A FEW HUNDRED JOULES OF CAPES OVR THE MTS AND PORTIONS OF THE I-25 CORRIDOR...WITH LAPSE RATES OF 8-9C/KM OVR THE FORECAST AREA. WL GO WITH SOME ISOLD THUNDERSTORMS CHANCES THIS AFTERNOON AND EARLY EVENING. FOR THIS AFTERNOON THE EASTERN SAN JUAN MTS SHOULD BE THE AREA THAT RECEIVES THE HEAVIEST SNOW...WITH THE REST OF THE CONTDVD SEEING SNOW...BUT NOT AS MUCH. DURING THE AFTERNOON SOME STRONG SOUTHERLY WINDS ARE EXPECTED TO DEVELOP OVR THE FAR SERN CORNER OF THE STATE WITH GUSTS OF 30-40 MPH. MIN RH VALUES IN THIS AREA ARE EXPECTED TO BE NR 15 PERCENT. HOWEVER FUELS IN THIS AREA ARE NOT CONSIDERED TO BE CRITICAL. HAVE ISSUED A WINTER WX ADVISORY FOR ZONE 67 AS WELL AND WL START IT IN THE LATE AFTERNOON TODAY. TEMPS IN THE EARLY AFTERNOON WL LIKELY BE TOO WARM TO SEE SNOW OR AT LEAST ANY REAL ACCUMULATIONS UNTIL TEMPS COOL TOWARD EVENING AND OVERNIGHT. BY 12Z SAT THE UPR LOW CENTER IS EXPECTED TO MOVE INTO THE SW CORNER OF CO. AS THIS OCCURS OVERNIGHT A DRY SLOT DEVELOPS OVR THE SERN PLAINS...AND SHOULD SEE DECREASING CHANCES FOR PCPN OVR THE SAN LUIS VALLEY AND SERN MTS. AT THE SAME TIME SNOW WL CONTINUE ALONG THE CONTDVD WITH THE EASTERN SAN JUAN MTS STILL BEING THE MOST FAVORED LOCATION FOR SIGNIFICANT SNOWFALL. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 506 AM MST FRI MAR 8 2013 ...QUICK MOVING STORM TO BRING SNOW AND BLOWING SNOW TO THE AREA SATURDAY... SATURDAY-SATURDAY NIGHT...LATEST MODELS REMAIN IN GOOD AGREEMENT OF A POTENT UPPER LOW ACROSS THE SOUTHERN CALIFORNIA COAST THIS MORNING LIFTING OUT INTO THE FOUR CORNERS REGION LATE TONIGHT WHICH THEN CONTINUES TO TRANSLATE ACROSS SOUTHERN COLORADO THROUGH THE DAY SATURDAY AND INTO NORTHWESTERN KANSAS SATURDAY NIGHT. MOVEMENT OF THIS SYSTEM KEEPS MODERATE TO HEAVY SNOWFALL ACROSS THE CONTDVD FRIDAY NIGHT AND SATURDAY WITH DEFORMATION BAND PRECIPITATION SPREADING EAST ACROSS SOUTH CENTRAL COLORADO AND THE EASTERN MTS SATURDAY MORNING AND AFTERNOON. MODELS REMAIN CONSISTENT WITH STRONG NORTHERLY WINDS DEVELOPING ACROSS THE EASTERN PLAINS LATE SATURDAY MORNING AND PERSISTING THROUGH THE EARLY EVENING AS AN ASSOCIATED COLD FRONT BLASTS ACROSS THE PLAINS. PRECIPITATION TYPE STILL IN QUESTION ACROSS THE PLAINS THOUGH MODEL SOUNDINGS INDICATING PRECIP RAPIDLY CHANGING OVER THE SNOW AOA 6K FT SATURDAY MORNING AND POSSIBLY LOWERING TO 4K FT UNDER THE HEAVIER BANDS AS THE SYSTEM LIFTS OUT ACROSS THE EASTERN PLAINS SATURDAY AFTERNOON AND EVENING. WITH THAT SAID...HAVE UPGRADED WINTER STORM WATCH TO A BLIZZARD WARNING FOR NORTHERN EL PASO COUNTY WITH 4-9 INCHES ALONG WITH STRONG NORTHERLY WINDS UP TO 30 MPH GUSTING TO NEAR 50 MPH AT TIMES...ESPECIALLY SATURDAY AFTERNOON. HAVE ALSO UPGRADED TELLER COUNTY AND THE RAMPART RANGE TO WINTER STORM WARNING WITH AMOUNTS RANGING FROM 6 TO 12 INCHES AND HAVE ISSUED WINTER WEATHER ADVISORIES FOR LAKE COUNTY...THE WESTERN MOSQUITO RANGE BELOW 9000 FEET AND NORTHWESTERN FREMONT COUNTY ABOVE 8500 FEET. HAVE ALSO ISSUED A WINTER STORM WATCH FOR THE SANGRE DE CRISTO AND WET MTS FROM SATURDAY MORNING THROUGH SATURDAY NIGHT. GFS IS STILL A BIT HEAVY HANDED WITH AMOUNTS ACROSS THE SOUTHEAST MTS AS WELL AS UNDER THE BANDS AND WILL NEED TO CONTINUE TO MONITOR FOR POSSIBLE ADDITIONS TO ADVISORIES AND WARNINGS. SUNDAY-WEDNESDAY...MODEL CONSENSUS CONTINUES TO INDICATE WARMER AND DRY CONDITIONS ACROSS THE AREA THROUGH THE REST OF EXTENDED PERIOD WITH MODERATE WESTERLY FLOW ACROSS THE REGION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 506 AM MST FRI MAR 8 2013 EXPECTED VFR CONDITIONS AT KPUB AND KCOS TODAY AND TONIGHT. LATE THIS AFTERNOON AND THIS EVENING THERE COULD BE A FEW SHOWERS OR EVEN A THUNDERSTORM AT OR IN THE VCNTY. KALS SHOULD HAVE VFR CONDITIONS BUT LATE THIS AFTERNOON SOME SHOWERS OR EVEN A THUNDERSTORM COULD RESULT IN BRIEF MVFR CONDITIONS. THERE IS ALSO THE POSSIBILITY OF SOME STRATUS OR BR TOWARD MORNING CAUSING MVFR CONDITIONS...ALTHOUGH CONFIDENCE IN THIS OCCURRING IT TOO LOW TO INCLUDE IN THE TAF AT THIS TIME. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM MST SATURDAY FOR COZ059-063-076. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR COZ072>075-079-080. WINTER STORM WARNING FROM 1 PM THIS AFTERNOON TO 11 PM MST SATURDAY FOR COZ058-060. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 5 PM MST SATURDAY FOR COZ067. WINTER STORM WARNING FROM 11 AM THIS MORNING TO 8 PM MST SATURDAY FOR COZ066-068. WINTER STORM WARNING FROM 5 AM TO 8 PM MST SATURDAY FOR COZ081- 082. BLIZZARD WARNING FROM 5 AM TO 8 PM MST SATURDAY FOR COZ084. && $$ SHORT TERM...28 LONG TERM...MW AVIATION...28
AREA FORECAST DISCUSSION
NWS NEW YORK NY
1054 AM EST FRI MAR 8 2013 .SYNOPSIS... DEEP LOW PRESSURE REMAINS NEARLY STATIONARY WELL TO THE SOUTHEAST THROUGH TODAY...THEN SLIDES SOUTHEAST TONIGHT. HIGH PRESSURE BUILDS OVER THE REGION FOR THE WEEKEND INTO MONDAY. MULTIPLE LOW PRESSURE SYSTEMS IMPACT THE NORTHEAST THROUGH MID WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MONITORING BAND OF MODERATE TO HEAVY SNOW THAT HAS DESCENDED UPON MOST OF THE STATE OF CT FROM THE NORTHEAST. LATEST HRRR INDICATES THIS BAND SHOULD CONTINUE TO DESCEND INTO COASTAL CT AND EVENTUALLY LONG ISLAND AS THE DAY PROGRESSES. UPGRADED SRN WESTCHESTER AND NORTHERN NASSAU...AS WELL AS MOST OF COASTAL CT...TO WINTER STORM WARNINGS WHERE SPOTTER REPORTS INDICATED 6-8 INCHES OF ACCUMULATION...WITH MORE TO FOLLOW WITH THE AFOREMENTIONED BAND INTO THIS AFTERNOON. ALSO SEEING SOME SPOTTY 6 INCH TOTALS ACROSS PARTS OF NW SUFFOLK COUNTY...SNOW THERE HAS LIGHTENED UP FOR THE TIME BEING...BUT AN ADDITIONAL 1-3 INCHES OF ACCUMULATION MAY BE POSSIBLE WITH THE BAND NOW OVER CT DURING THE LATE MORNING AND AFTERNOON. WHILE AMTS OVER SUFFOLK SHOULD RANGE FROM 4-8 INCHES...HAVE NOT UPGRADED TO A WARNING THERE MAINLY DUE TO THE RELATIVELY LONG DURATION OF SNOWFALL. ELSEWHERE...WARNINGS/ADVISORIES THAT WERE ALREADY IN EFFECT WERE EXTENDED A LITTLE LONGER INTO EARLY AFTERNOON ACROSS NYC METRO AND NE NJ...AND WERE EXTENDED INTO THE AFTERNOON FARTHER EAST. GUSTY NORTHERLY WINDS WILL PICK UP THROUGH THE DAY...WITH WINDS OF 20 TO 30 MPH AND GUSTS 35 TO 45 MPH. THERE IS A LOW PROBABILITY OF WIND ADVISORY WINDS. WITH CLOUDS AND PRECIP TEMPS WILL RUN SEVERAL DEGREES BELOW AVG... AROUND 40 IN NYC METRO...AND MID/UPPER 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... STACKED LOW PRESSURE GRADUALLY DRIFTS FARTHER OFFSHORE TONIGHT WITH RIDGING SURFACE/ALOFT GRADUALLY BUILDING TOWARDS THE REGION. THIS WILL ALLOW FOR A GRADUAL SUBSIDING OF WINDS AND CLEARING SKIES. RIDGING CONTINUES TO BUILDS INTO THE REGION ON SATURDAY...WITH GUSTY NORTHERLY WINDS IN THE MORNING GRADUALLY RELAXING THROUGH THE AFTERNOON. OTHERWISE...MOSTLY SUNNY SKIES AND SLIGHTLY ABOVE SEASONABLE TEMPS EXPECTED IN A MODERATING AIR MASS. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... GENERALLY DECENT MODEL AGREEMENT FOR THE WEEKEND AND INTO THE BEGINNING OF THE COMING WEEK. SOME MODEL DIVERGENCE ON THE HANDLING OF THE FIRST LOW PRESSURE SYSTEM AND ACCOMPANYING COLD FRONT LATER MONDAY AND THE DEVELOPMENT OF A SECONDARY LOW INTO TUESDAY. SURFACE HIGH PRESSURE EXTENDS DOWN ACROSS THE EASTERN SEABOARD SAT NIGHT INTO SUNDAY WHILE AN UPPER LEVEL RIDGE SETS UP OVERHEAD BY SUNDAY. THIS WILL PRODUCE QUIET CONDITIONS...WITH A LIGHT FLOW AND PARTLY CLOUDY SKIES. WARM AIR ADVECTION INCREASES SUNDAY AS THE HIGH PUSHES TO THE EAST...SHIFTING WINDS TO THE SOUTHEAST. AS A RESULT...HIGH TEMPS ON SUNDAY WILL PUSH INTO THE UPPER 40S TO LOWER 50S...A FEW DEGREES ABOVE NORMAL. A LOW PRESSURE SYSTEM MOVING THROUGH SOUTHERN CANADA WILL APPROACH WITH A COLD FRONT MONDAY. STRONG SOUTHERLY FLOW AHEAD OF THIS FRONT WILL KEEP INCREASING THE WAA...WITH HIGH TEMPS ON MONDAY HITTING THE UPPER 50S AROUND THE NYC METRO AREA...AND LOWER 50S ELSEWHERE. A WEAK SHORTWAVE MOVING THROUGH MONDAY MORNING COULD BRING A SLIGHT CHC OF RAIN. CAPPED POPS OFF AT HIGHER END CHC FOR MONDAY AFTN INTO TUES WITH SOME MODEL DISCREPANCIES ON THE HANDLING OF THE FRONT AND A DEVELOPING LOW OVER THE TENNESSEE VALLEY REGION AT THE END OF THE FRONT. THE MODELS GENERALLY AGREE THAT THE COLD FRONT DOES NOT ACTUALLY PUSH THROUGH THE TRI STATE AREA. BUT THE 00Z ECMWF IS MUCH MORE PROGRESSIVE ON THE SECONDARY LOW MOVING THROUGH THE EASTERN GREAT LAKES REGION MONDAY NIGHT...AND THEN DRAGGING A COLD FRONT/TROUGH THROUGH TUESDAY...WHILE THE 00Z GFS IS FURTHER TO THE EAST WITH THE CENTER DIRECTLY OVER THE TRI STATE REGION AND A GOOD 12 HOURS SLOWER. SO WHILE THE TIMING OF THE PCPN IS STILL TO BE DETERMINED...HIGHER CONFIDENCE THAT THE TRACK OF EITHER SOLUTION WOULD KEEP ANY PCPN AS RAIN OVER THE ENTIRE AREA THROUGH TUESDAY. MODELS CONTINUE TO DIVERGE MIDWEEK WITH THE ECMWF DEEPENING AN UPPER LEVEL CLOSED LOW OVER THE NORTHEAST WHILE THE GFS RETURNS TO ALMOST A ZONAL FLOW WITH HIGH PRESSURE AT THE SURFACE. WITH THE 00Z MODEL RUNS TRENDING MUCH DIFFERENT THAN PREVIOUS RUNS...AND WITH SUCH DIFFERENCES BETWEEN THEMSELVES EVEN...WILL NOT MAKE MANY CHANGES FOR THE LATTER PART OF THE PERIOD. SLIGHT CHC POPS REMAIN IN THE FORECAST FOR WED INTO THURS TO ACCOUNT FOR A DEVELOPING TROUGH OVER NEW ENGLAND. WEAK COLD AIR ADVECTION WILL BE SLOW TO MOVE INTO THE REGION...SO TEMPS REMAIN NEAR TO SLIGHTLY ABOVE NORMAL FOR MID WEEK. WITH TEMPS GRADUALLY DECREASING...SHOULD SEE AT LEAST MIXED PCPN...WITH POSSIBLY ALL SNOW WED NIGHT. && .AVIATION /16Z FRIDAY THROUGH TUESDAY/... SNOW ASSOCIATED WITH LOW PRESSURE OFFSHORE WILL PRESENT WIDESPREAD IFR/LIFR CONDITIONS WITH VLIFR AT TIMES INTO EARLY AFTERNOON WITH HEAVIER SNOW. THERE COULD BE SOME AREAS THAT ARE OCCASIONALLY MVFR BUT THINK THIS WILL BE QUITE LOCALIZED. SLOW IMPROVEMENT LATER IN THE AFTERNOON WITH LIGHTER SNOWFALL AND MORE IN THE WAY OF MVFR/IFR CONDITIONS. LOW CONFIDENCE ON EXACT TIMING OF IMPROVING CONDITIONS AND END TIME OF SNOWFALL WITH AMENDMENTS LIKELY TO REFINE THIS TIMING AS WELL AS WHEN VLIFR BECOMES LIKELY. HIGHER CONFIDENCE OF DRYING AND IMPROVING CONDITIONS THIS EVENING AFTER 00Z. HIGHER CONFIDENCE WITH WIND FORECAST. WIND DIRECTION STAYING IN THE 340-360 RANGE AND SUSTAINED SPEEDS OF 15-25 KT WITH GUSTS IN THE 25-35 KT RANGE WITH THE PEAK GUSTS THIS AFTERNOON. WINDS GRADUALLY LOWER TONIGHT. LOW LEVEL WINDS INCREASE WITH THE LOW LEVEL JET MOVING IN...INCREASING WINDS TO 45-50 KT AT 2KFT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KEWR FCSTER COMMENTS: AMENDMENTS LIKELY TO REFINE TIMING THE END OF SNOW AS WELL AS LOWER CIGS AND VSBY...WHICH COULD BE OFF BY 1-2 HOURS. OCCASIONAL HEAVY SNOW WITH VLIFR POSSIBLE. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KJFK FCSTER COMMENTS: AMENDMENTS LIKELY TO REFINE TIMING THE END OF SNOW AS WELL AS LOWER CIGS AND VSBY...WHICH COULD BE OFF BY 1-2 HOURS. OCCASIONAL HEAVY SNOW WITH VLIFR POSSIBLE. KLGA FCSTER COMMENTS: AMENDMENTS LIKELY TO REFINE TIMING THE END OF SNOW AS WELL AS LOWER CIGS AND VSBY...WHICH COULD BE OFF BY 1-2 HOURS. OCCASIONAL HEAVY SNOW WITH VLIFR POSSIBLE. KTEB FCSTER COMMENTS: AMENDMENTS LIKELY TO REFINE TIMING THE END OF SNOW AS WELL AS LOWER CIGS AND VSBY...WHICH COULD BE OFF BY 1-2 HOURS. OCCASIONAL HEAVY SNOW WITH VLIFR POSSIBLE. KHPN FCSTER COMMENTS: AMENDMENTS LIKELY TO REFINE TIMING THE END OF SNOW AS WELL AS LOWER CIGS AND VSBY...WHICH COULD BE OFF BY 1-2 HOURS. OCCASIONAL HEAVY SNOW WITH VLIFR POSSIBLE. KISP FCSTER COMMENTS: AMENDMENTS LIKELY TO REFINE TIMING THE END OF SNOW AS WELL AS LOWER CIGS AND VSBY...WHICH COULD BE OFF BY 1-2 HOURS. OCCASIONAL HEAVY SNOW WITH VLIFR POSSIBLE. OUTLOOK FOR 06Z SATURDAY THROUGH WEDNESDAY... .TONIGHT...VFR WITH DECREASING NORTH WINDS. .SAT-SUN...VFR. .MON...VFR...INCREASING S WINDS LATE IN THE DAY. .TUE...COLD FRONTAL PASSAGE WITH RAIN SHOWERS. SUB-VFR CONDITIONS EXPECTED. .WED...VFR. && .MARINE... GALES EXPECTED ON ALL WATERS TODAY AS THE PRESSURE GRADIENT SLIGHTLY TIGHTENS BETWEEN STATIONARY OFFSHORE LOW PRESSURE AND HIGH PRESSURE BUILDING INTO WESTERN NY. GALES SHOULD THEN GRADUALLY SUBSIDE TO SCA FROM W TO E THIS EVENING...AND THEN GRADUALLY FALLING BELOW SCA ON SAT. LONG PERIOD EASTERLY SWELLS WILL LIKELY KEEP SEAS HIGH ON THE OCEAN INTO SAT...10-15 FT. SEAS ON THE OCEAN WILL REMAIN ELEVATED AROUND 5 FT SAT NIGHT INTO SUNDAY...GRADUALLY DIMINISHING AS THE WINDS DECREASE WITH HIGH PRESSURE BUILDS IN. A BRIEF PERIOD OF SUB-SCA CONDITIONS IS EXPECTED MONDAY BEFORE WINDS AND SEAS INCREASE ONCE AGAIN WITH THE NEXT LOW PRESSURE SYSTEM TO SCA LEVELS. DEPENDING ON THE TRACK OF THE LOW MIDWEEK...THERE MAY BE A CHANCE OF GALES ON THE OCEAN WATERS. BUT VERY LOW CONFIDENCE AT THIS TIME OF OCCURRING. && .HYDROLOGY... TOTAL LIQUID EQUIVALENT QPF TONIGHT THROUGH FRI IS FORECAST TO RANGE FROM AROUND ONE THIRD TO THREE QUARTERS OF AN INCH. HYDRO RELATED ISSUES ARE NOT ANTICIPATED AT THIS TIME. DRY WEATHER FOR THE WEEKEND...THEN LIGHT TO MODERATE PRECIPITATION AMOUNTS WILL BE POSSIBLE MONDAY NIGHT INTO TUESDAY. && .TIDES/COASTAL FLOODING... RESIDUAL SURGE OF 1 1/2 TO 2 1/2 FT WILL RESULT IN WIDESPREAD MINOR COASTAL FLOODING EXPECTED WITH THIS MORNING HIGH TIDES ACROSS THE ENTIRE COAST. FOR THE LOWER HIGH TIDE THIS AFT/EVE WATER LEVELS WILL LIKELY ONLY TOUCH MINOR LEVELS ACROSS THE SOUTH SHORE BAYS OF LI...TWIN FORKS AND WESTERN AND CENTRAL LI SOUND...INCLUDING THE NORTH SHORE OF LI. MODERATE BEACH EROSION ISSUES WILL CONTINUE INTO SATURDAY FOR OCEAN FACING BEACHES AND TWIN FORKS OF LI WITH BREAKERS BETWEEN 7 TO 11 FT...HIGHEST EAST OF MORICHES INLET. LOOKING TOWARDS THE WEEKEND...FURTHER INCREASES IN ASTRONOMICAL LEVELS AS WE GET CLOSER TO THE TIME OF THE NEW MOON WILL KEEP THE POTENTIAL FOR MINOR COASTAL FLOODING OVERALL TO LOCALLY MODERATE COASTAL FLOODING FOR BAY LOCATIONS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR CTZ012. WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR CTZ005>011. NY...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ078>081. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR NYZ067>070. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ072>075-176-178-179. WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR NYZ071- 177. NJ...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR NJZ002- 004-103. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NJZ006-104>108. MARINE...GALE WARNING UNTIL 6 AM EST SATURDAY FOR ANZ330-335-338-340- 345-350-353-355. && $$ SYNOPSIS...SEARS/NV NEAR TERM...GOODMAN/NV SHORT TERM...NV LONG TERM...JC/SEARS AVIATION...GC/JM MARINE...SEARS/NV HYDROLOGY...SEARS/NV TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS NEW YORK NY
949 AM EST FRI MAR 8 2013 .SYNOPSIS... DEEP LOW PRESSURE REMAINS NEARLY STATIONARY WELL TO THE SOUTHEAST THROUGH TODAY...THEN SLIDES SOUTHEAST TONIGHT. HIGH PRESSURE BUILDS OVER THE REGION FOR THE WEEKEND INTO MONDAY. MULTIPLE LOW PRESSURE SYSTEMS IMPACT THE NORTHEAST THROUGH MID WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MONITORING BAND OF MODERATE TO HEAVY SNOW THAT HAS DESCENDED UPON MOST OF THE STATE OF CT FROM THE NORTHEAST. LATEST HRRR INDICATES THIS BAND SHOULD CONTINUE TO DESCEND INTO COASTAL CT AND EVENTUALLY LONG ISLAND AS THE DAY PROGRESSES. UPGRADED SRN WESTCHESTER AND NORTHERN NASSAU...AS WELL AS MOST OF COASTAL CT...TO WINTER STORM WARNINGS WHERE SPOTTER REPORTS INDICATED 6-8 INCHES OF ACCUMULATION...WITH MORE TO FOLLOW WITH THE AFOREMENTIONED BAND INTO THIS AFTERNOON. ALSO SEEING SOME SPOTTY 6 INCH TOTALS ACROSS PARTS OF NW SUFFOLK COUNTY...SNOW THERE HAS LIGHTENED UP FOR THE TIME BEING...BUT AN ADDITIONAL 1-3 INCHES OF ACCUMULATION MAY BE POSSIBLE WITH THE BAND NOW OVER CT DURING THE LATE MORNING AND AFTERNOON. WHILE AMTS OVER SUFFOLK SHOULD RANGE FROM 4-8 INCHES...HAVE NOT UPGRADED TO A WARNING THERE MAINLY DUE TO THE RELATIVELY LONG DURATION OF SNOWFALL. ELSEWHERE...WARNINGS/ADVISORIES THAT WERE ALREADY IN EFFECT WERE EXTENDED A LITTLE LONGER INTO EARLY AFTERNOON ACROSS NYC METRO AND NE NJ...AND WERE EXTENDED INTO THE AFTERNOON FARTHER EAST. GUSTY NORTHERLY WINDS WILL PICK UP THROUGH THE DAY...WITH WINDS OF 20 TO 30 MPH AND GUSTS 35 TO 45 MPH. THERE IS A LOW PROBABILITY OF WIND ADVISORY WINDS. WITH CLOUDS AND PRECIP TEMPS WILL RUN SEVERAL DEGREES BELOW AVG... AROUND 40 IN NYC METRO...AND MID/UPPER 30S ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/... STACKED LOW PRESSURE GRADUALLY DRIFTS FARTHER OFFSHORE TONIGHT WITH RIDGING SURFACE/ALOFT GRADUALLY BUILDING TOWARDS THE REGION. THIS WILL ALLOW FOR A GRADUAL SUBSIDING OF WINDS AND CLEARING SKIES. RIDGING CONTINUES TO BUILDS INTO THE REGION ON SATURDAY...WITH GUSTY NORTHERLY WINDS IN THE MORNING GRADUALLY RELAXING THROUGH THE AFTERNOON. OTHERWISE...MOSTLY SUNNY SKIES AND SLIGHTLY ABOVE SEASONABLE TEMPS EXPECTED IN A MODERATING AIR MASS. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... GENERALLY DECENT MODEL AGREEMENT FOR THE WEEKEND AND INTO THE BEGINNING OF THE COMING WEEK. SOME MODEL DIVERGENCE ON THE HANDLING OF THE FIRST LOW PRESSURE SYSTEM AND ACCOMPANYING COLD FRONT LATER MONDAY AND THE DEVELOPMENT OF A SECONDARY LOW INTO TUESDAY. SURFACE HIGH PRESSURE EXTENDS DOWN ACROSS THE EASTERN SEABOARD SAT NIGHT INTO SUNDAY WHILE AN UPPER LEVEL RIDGE SETS UP OVERHEAD BY SUNDAY. THIS WILL PRODUCE QUIET CONDITIONS...WITH A LIGHT FLOW AND PARTLY CLOUDY SKIES. WARM AIR ADVECTION INCREASES SUNDAY AS THE HIGH PUSHES TO THE EAST...SHIFTING WINDS TO THE SOUTHEAST. AS A RESULT...HIGH TEMPS ON SUNDAY WILL PUSH INTO THE UPPER 40S TO LOWER 50S...A FEW DEGREES ABOVE NORMAL. A LOW PRESSURE SYSTEM MOVING THROUGH SOUTHERN CANADA WILL APPROACH WITH A COLD FRONT MONDAY. STRONG SOUTHERLY FLOW AHEAD OF THIS FRONT WILL KEEP INCREASING THE WAA...WITH HIGH TEMPS ON MONDAY HITTING THE UPPER 50S AROUND THE NYC METRO AREA...AND LOWER 50S ELSEWHERE. A WEAK SHORTWAVE MOVING THROUGH MONDAY MORNING COULD BRING A SLIGHT CHC OF RAIN. CAPPED POPS OFF AT HIGHER END CHC FOR MONDAY AFTN INTO TUES WITH SOME MODEL DISCREPANCIES ON THE HANDLING OF THE FRONT AND A DEVELOPING LOW OVER THE TENNESSEE VALLEY REGION AT THE END OF THE FRONT. THE MODELS GENERALLY AGREE THAT THE COLD FRONT DOES NOT ACTUALLY PUSH THROUGH THE TRI STATE AREA. BUT THE 00Z ECMWF IS MUCH MORE PROGRESSIVE ON THE SECONDARY LOW MOVING THROUGH THE EASTERN GREAT LAKES REGION MONDAY NIGHT...AND THEN DRAGGING A COLD FRONT/TROUGH THROUGH TUESDAY...WHILE THE 00Z GFS IS FURTHER TO THE EAST WITH THE CENTER DIRECTLY OVER THE TRI STATE REGION AND A GOOD 12 HOURS SLOWER. SO WHILE THE TIMING OF THE PCPN IS STILL TO BE DETERMINED...HIGHER CONFIDENCE THAT THE TRACK OF EITHER SOLUTION WOULD KEEP ANY PCPN AS RAIN OVER THE ENTIRE AREA THROUGH TUESDAY. MODELS CONTINUE TO DIVERGE MIDWEEK WITH THE ECMWF DEEPENING AN UPPER LEVEL CLOSED LOW OVER THE NORTHEAST WHILE THE GFS RETURNS TO ALMOST A ZONAL FLOW WITH HIGH PRESSURE AT THE SURFACE. WITH THE 00Z MODEL RUNS TRENDING MUCH DIFFERENT THAN PREVIOUS RUNS...AND WITH SUCH DIFFERENCES BETWEEN THEMSELVES EVEN...WILL NOT MAKE MANY CHANGES FOR THE LATTER PART OF THE PERIOD. SLIGHT CHC POPS REMAIN IN THE FORECAST FOR WED INTO THURS TO ACCOUNT FOR A DEVELOPING TROUGH OVER NEW ENGLAND. WEAK COLD AIR ADVECTION WILL BE SLOW TO MOVE INTO THE REGION...SO TEMPS REMAIN NEAR TO SLIGHTLY ABOVE NORMAL FOR MID WEEK. WITH TEMPS GRADUALLY DECREASING...SHOULD SEE AT LEAST MIXED PCPN...WITH POSSIBLY ALL SNOW WED NIGHT. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... LOWER CONFIDENCE IN TIMING THE END OF SNOW FROM EAST TO WEST ASSOCIATED WITH LOWER CIGS AND VSBY... WIDESPREAD MVFR CIGS AND MVFR VSBY WILL CONT UNTIL 15Z-18Z AS SNOW MOVES WEST ACROSS THE REGION. BANDS OF MODERATE SNOW WILL TEMPORARILY REDUCE CIGS TO IFR AND VSBY TO LIFR UNTIL 16Z FROM THE NYC METRO AREA EAST INCLUDING AT KJFK AND KLGA. CIGS AND VSBY WILL GRADUALLY IMPROVE AFT 18Z...BECOMING VFR BY 21Z. HIGH CONFIDENCE IN WIND FORECAST... N TO NW WINDS FROM 330-350 DEG WILL GRADUALLY INCREASE AND PEAK FROM 15Z TO 21Z...REACHING SUSTAINED SPEEDS OF 20-25 KT FROM NYC EAST WITH GUSTS OF 30-34 KT. WEST OF NYC INCLUDING KEWR...SUSTAINED WINDS WILL INCREASE TO 15-20 KT WITH GUSTS OF 25-30 KT. N TO NW WINDS WILL GRADUALLY DECREASE AFT SUNSET BECOMING 10-15 KT WITH GUSTS OF 20-25 KT. NY METRO ENHANCED AVIATION WEATHER SUPPORT... DETAILED INFORMATION...INCLUDING HOURLY TAF WIND COMPONENT FCSTS CAN BE FOUND AT: HTTP:/WWW.ERH.NOAA.GOV/ZNY/N90 (LOWER CASE) KEWR FCSTER COMMENTS: TIMING THE END OF SNOW WITH LOWER CIGS AND VSBY COULD BE OFF BY A FEW HOURS. THE AFTERNOON KEWR HAZE POTENTIAL FORECAST IS GREEN...WHICH IMPLIES SLANT RANGE VISIBILITY 7SM OR GREATER OUTSIDE OF CLOUD. KJFK FCSTER COMMENTS: TIMING THE END OF SNOW WITH LOWER CIGS AND VSBY COULD BE OFF BY A FEW HOURS. KLGA FCSTER COMMENTS: TIMING THE END OF SNOW WITH LOWER CIGS AND VSBY COULD BE OFF BY A FEW HOURS. KTEB FCSTER COMMENTS: TIMING THE END OF SNOW WITH LOWER CIGS AND VSBY COULD BE OFF BY A FEW HOURS. KHPN FCSTER COMMENTS: TIMING THE END OF SNOW WITH LOWER CIGS AND VSBY COULD BE OFF BY A FEW HOURS. KISP FCSTER COMMENTS: TIMING THE END OF SNOW WITH LOWER CIGS AND VSBY COULD BE OFF BY A FEW HOURS. OUTLOOK FOR 06Z SATURDAY THROUGH WEDNESDAY... .TONIGHT...VFR WITH DECREASING NORTH WINDS. .SAT-SUN...VFR. .MON...VFR...INCREASING S WINDS LATE IN THE DAY. .TUE...COLD FRONTAL PASSAGE WITH RAIN SHOWERS. SUB-VFR CONDITIONS EXPECTED. .WED...VFR. && .MARINE... GALES EXPECTED ON ALL WATERS TODAY AS THE PRESSURE GRADIENT SLIGHTLY TIGHTENS BETWEEN STATIONARY OFFSHORE LOW PRESSURE AND HIGH PRESSURE BUILDING INTO WESTERN NY. GALES SHOULD THEN GRADUALLY SUBSIDE TO SCA FROM W TO E THIS EVENING...AND THEN GRADUALLY FALLING BELOW SCA ON SAT. LONG PERIOD EASTERLY SWELLS WILL LIKELY KEEP SEAS HIGH ON THE OCEAN INTO SAT...10-15 FT. SEAS ON THE OCEAN WILL REMAIN ELEVATED AROUND 5 FT SAT NIGHT INTO SUNDAY...GRADUALLY DIMINISHING AS THE WINDS DECREASE WITH HIGH PRESSURE BUILDS IN. A BRIEF PERIOD OF SUB-SCA CONDITIONS IS EXPECTED MONDAY BEFORE WINDS AND SEAS INCREASE ONCE AGAIN WITH THE NEXT LOW PRESSURE SYSTEM TO SCA LEVELS. DEPENDING ON THE TRACK OF THE LOW MIDWEEK...THERE MAY BE A CHANCE OF GALES ON THE OCEAN WATERS. BUT VERY LOW CONFIDENCE AT THIS TIME OF OCCURRING. && .HYDROLOGY... TOTAL LIQUID EQUIVALENT QPF TONIGHT THROUGH FRI IS FORECAST TO RANGE FROM AROUND ONE THIRD TO THREE QUARTERS OF AN INCH. HYDRO RELATED ISSUES ARE NOT ANTICIPATED AT THIS TIME. DRY WEATHER FOR THE WEEKEND...THEN LIGHT TO MODERATE PRECIPITATION AMOUNTS WILL BE POSSIBLE MONDAY NIGHT INTO TUESDAY. && .TIDES/COASTAL FLOODING... RESIDUAL SURGE OF 1 1/2 TO 2 1/2 FT WILL RESULT IN WIDESPREAD MINOR COASTAL FLOODING EXPECTED WITH THIS MORNING HIGH TIDES ACROSS THE ENTIRE COAST. FOR THE LOWER HIGH TIDE THIS AFT/EVE WATER LEVELS WILL LIKELY ONLY TOUCH MINOR LEVELS ACROSS THE SOUTH SHORE BAYS OF LI...TWIN FORKS AND WESTERN AND CENTRAL LI SOUND...INCLUDING THE NORTH SHORE OF LI. MODERATE BEACH EROSION ISSUES WILL CONTINUE INTO SATURDAY FOR OCEAN FACING BEACHES AND TWIN FORKS OF LI WITH BREAKERS BETWEEN 7 TO 11 FT...HIGHEST EAST OF MORICHES INLET. LOOKING TOWARDS THE WEEKEND...FURTHER INCREASES IN ASTRONOMICAL LEVELS AS WE GET CLOSER TO THE TIME OF THE NEW MOON WILL KEEP THE POTENTIAL FOR MINOR COASTAL FLOODING OVERALL TO LOCALLY MODERATE COASTAL FLOODING FOR BAY LOCATIONS. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR CTZ012. COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR CTZ009>012. WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR CTZ005>011. NY...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR NYZ078>081. COASTAL FLOOD ADVISORY UNTIL 11 AM EST THIS MORNING FOR NYZ071- 073-078-079-081-176-177. WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR NYZ067>070. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NYZ072>075-176-178-179. WINTER STORM WARNING UNTIL 6 PM EST THIS EVENING FOR NYZ071- 177. COASTAL FLOOD ADVISORY UNTIL 10 AM EST THIS MORNING FOR NYZ080- 179. NJ...WINTER STORM WARNING UNTIL 1 PM EST THIS AFTERNOON FOR NJZ002- 004-103. WINTER WEATHER ADVISORY UNTIL 1 PM EST THIS AFTERNOON FOR NJZ006-104>108. MARINE...GALE WARNING UNTIL 6 AM EST SATURDAY FOR ANZ330-335-338-340- 345-350-353-355. && $$ SYNOPSIS...SEARS/NV NEAR TERM...GOODMAN SHORT TERM...NV LONG TERM...JC/SEARS AVIATION...GC MARINE...SEARS/NV HYDROLOGY...SEARS/NV TIDES/COASTAL FLOODING...SEARS
AREA FORECAST DISCUSSION
NWS TOPEKA KS
527 AM CST FRI MAR 8 2013 ...UPDATE TO AVIATION... .DISCUSSION... SHORT RANGE FORECAST (TODAY THROUGH SATURDAY)... 09Z RAP ANALYSIS AND SURFACE OBS SHOW A TIGHTENING SURFACE PRESSURE GRADIENT TAKING FORM ACROSS THE AREA AS AN AREA OF LOW PRESSURE SITS OVER SE COLORADO. WATER VAPOR IMAGERY INDICATES THAT A MID TO UPPER LEVEL TROUGH CURRENTLY SITS OVER SOUTHERN CALIFORNIA...WITH A STRONG SOUTH/SOUTHWEST COMPONENT TO THE MID/UPPER WINDS WELL TO THE EAST OF THE TROUGH CENTER. WITHIN THIS MID LEVEL SOUTHERLY FLOW WATER VAPOR IMAGERY SHOWS SOME MOISTURE WORKING ITS WAY THROUGH THE SOUTHERN HIGH PLAINS INTO WESTERN KANSAS. THIS TROUGH WILL BE THE IMPETUS BEHIND RAIN CHANCES LATER TONIGHT THROUGH THE WEEKEND. AS THE SURFACE TROUGH TAKES FORM THE SURFACE PRESSURE GRADIENT WILL BECOME A BIT STRONGER ALLOWING FOR THE WINDS TO PICK UP THROUGHOUT THE DAY. EXPECT S/SE WINDS TO EVENTUALLY INCREASE TO BETWEEN 15 AND 25 MPH...WITH GUSTS UP TO 30. LOW LEVEL SOUTHERLY WINDS WILL ALSO TRANSPORT WARM/MOIST AIR INTO THE AREA. EXPECT DEWPOINTS TO INCREASE THROUGHOUT THE DAY TO THE MID 40S BY LATE TONIGHT. ISENTROPIC CHARTS SHOW A STRONG ISENTROPIC COMPONENT WITHIN THE S/SE LOW AND MID LEVEL WINDS WHICH MAY LEAD TO INCREASING CLOUDS THROUGH THE AFTERNOON HOURS...HOWEVER CONDENSATION PRESSURE DEFICITS LOOK TO REMAIN TOO HIGH TO PRODUCE ANY PRECIPITATION UNTIL LATER THIS EVENING. WITH THE MAIN AREA OF MID LEVEL ENERGY HANGING OFF TO THE WEST THE MAIN INFLUENCE FOR FRIDAY NIGHT PRECIP WILL BE THE STRONG ISENTROPIC COMPONENT. FORECAST SOUNDING CORROBORATE WHAT THE ISENTROPIC SURFACES SUGGEST...WHICH IS THAT THE COLUMN WILL HAVE SOME DRY AIR TO OVERCOME THROUGHOUT THE DAY ON FRIDAY. EVENTUALLY IT WILL OVERCOME THE DRY AIR AND PRECIP WILL BEGIN FRIDAY EVENING. PRECIP COVERAGE AND INTENSITY WILL INCREASE THROUGH THE NIGHT AS THE COLUMN BECOMES COMPLETELY SATURATED. BY LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING THE MID LEVEL TROUGH WILL BEGIN MOVING THROUGH THE AREA. THE EXTRA LARGE SCALE ASCENT SHOULD ALLOW FOR MORE EFFICIENT RAIN PROCESSES...CAUSING PERIODS OF MODERATE RAIN TO OCCUR THROUGH MID DAY ON SATURDAY. ALONG WITH THE BETTER LARGE SCALE ASCENT THE COOLER TEMPS ALOFT ASSOCIATED WITH THE LARGE TROUGH WILL ALLOW FOR SOME ELEVATED STEEP LAPSE RATES...MAKING ELEVATED CAPE LEVELS APPROACH 500 J/KG. AS A RESULT PERIODS OF THUNDERSTORMS WILL BE LIKELY LATE FRIDAY NIGHT THROUGH THE DAY ON SATURDAY. ALTHOUGH THE THUNDERSTORMS ARE NOT EXPECTED TO BE VIGOROUS THE MODEST CAPE ALONG WITH 40 TO 50 KTS OF 0-6 SHEAR IT IS POSSIBLE THAT AN ISOLATED CELL OR TWO COULD BECOME STRONG WITH PERHAPS A SEVERE HAIL REPORT OR TWO SATURDAY MORNING/AFTERNOON. AS THE SYSTEM PROGRESSES TO THE EAST MODELS SEEM TO AGREE ON THE PLACEMENT AND TIMING OF A DRY SLOT OF MID LEVEL AIR CUTTING OFF THE EFFICIENT PRECIP PROCESSES BY SATURDAY AFTERNOON/EVENING. THIS WILL LIKELY SPELL AN END TO THE MODERATE PRECIP...ALTHOUGH SOME LIGHT PRECIP MAY LINGER THROUGH LATE SATURDAY NIGHT. ACROSS THE NORTHERN COUNTIES THERE WILL REMAIN A CHANCE FOR SOME VERY LIGHT SNOW FALL SATURDAY NIGHT AS A WEAK TROWAL FORMS ACROSS CENTRAL NEBRASKA. GIVEN THAT THE REGION WILL EXPERIENCE SEVERAL DAYS IN A ROW OF ABOVE FREEZING TEMPERATURES AS WELL AS A WET GROUND FROM THE SATURDAY RAINFALL EXPECT SNOW ACCUMULATIONS TO BE TOUGH TO COME BY. PERHAPS A DUSTING OF SNOW WILL BE POSSIBLE ON GRASSY AND ELEVATED SURFACES...BUT EXPECT PAVED SURFACES TO STAY WET AS OPPOSED TO SNOW PACKED. BY SUNDAY AFTERNOON THE SYSTEM SHOULD MOVE OFF TO THE EAST ENDING ALL PRECIPITATIONS CHANCES. QPF FORECAST FOR THIS SYSTEM REMAINS A BIT CONSERVATIVE AS MODELS HAVE OVERDONE PRECIP AMOUNT IN RECENT SYSTEMS. ON THE LOWER END THIS SYSTEM SHOULD HAVE NO PROBLEM PRODUCING A QUARTER INCH OF PRECIPITATION AREA-WIDE...WITH PERHAPS A FEW ISOLATED AREAS GETTING A FULL INCH. MOST AREAS WILL LIKELY GET SOMEWHERE BETWEEN THOSE TWO VALUES IN LIQUID PRECIP BETWEEN FRIDAY NIGHT AND SUNDAY MORNING. MID RANGE AND EXTENDED FORECAST (MONDAY THROUGH THURSDAY)... A STRONG PUSH OF COLD AIR WILL FOLLOW THE SYSTEM THROUGH THE AREA AND TO THE EAST. THIS PUSH OF COLD AIR WILL LIKELY BRING A COOL DOWN FOR SUNDAY AND MONDAY BEFORE SOUTHERLY FLOW RECOMMENCES...BRINGING WARM/MOIST AIR BACK INTO THE AREA. FOR A FEW DAYS NOW MODELS HAVE SHOWN THAT THE AREA WILL STAY DRY THROUGH NEXT WORK WEEK WITH A GRADUAL...BUT NOTICEABLE WARM UP. WITH A MID LEVEL RIDGE OFF TO THE WEST...GRADUALLY CREEPING EASTWARD THROUGH THE WEEK AND MOSTLY PERSISTENT SOUTHERLY FLOW EXPECT TUESDAY THROUGH THURSDAY TO BRING ABOVE SEASONALLY NORMAL TEMPERATURES. JL && .AVIATION... LLWS CONTINUES EARLY THIS MORNING BEFORE WINDS PICK UP AND MIX OUT AROUND 14Z. CLOUDS SLOWLY INCREASE AND LOWER THROUGH THE PERIOD...WITH VICINITY SHRA/TSRA EXPECTED BY LATE AFTERNOON. PREVAILING TS BEST CHANCE OF MOVING IN AFTER MIDNIGHT. 67 && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
413 AM CST FRI MAR 8 2013 .DISCUSSION... SHORT RANGE FORECAST (TODAY THROUGH SATURDAY)... 09Z RAP ANALYSIS AND SURFACE OBS SHOW A TIGHTENING SURFACE PRESSURE GRADIENT TAKING FORM ACROSS THE AREA AS AN AREA OF LOW PRESSURE SITS OVER SE COLORADO. WATER VAPOR IMAGERY INDICATES THAT A MID TO UPPER LEVEL TROUGH CURRENTLY SITS OVER SOUTHERN CALIFORNIA...WITH A STRONG SOUTH/SOUTHWEST COMPONENT TO THE MID/UPPER WINDS WELL TO THE EAST OF THE TROUGH CENTER. WITHIN THIS MID LEVEL SOUTHERLY FLOW WATER VAPOR IMAGERY SHOWS SOME MOISTURE WORKING ITS WAY THROUGH THE SOUTHERN HIGH PLAINS INTO WESTERN KANSAS. THIS TROUGH WILL BE THE IMPETUS BEHIND RAIN CHANCES LATER TONIGHT THROUGH THE WEEKEND. AS THE SURFACE TROUGH TAKES FORM THE SURFACE PRESSURE GRADIENT WILL BECOME A BIT STRONGER ALLOWING FOR THE WINDS TO PICK UP THROUGHOUT THE DAY. EXPECT S/SE WINDS TO EVENTUALLY INCREASE TO BETWEEN 15 AND 25 MPH...WITH GUSTS UP TO 30. LOW LEVEL SOUTHERLY WINDS WILL ALSO TRANSPORT WARM/MOIST AIR INTO THE AREA. EXPECT DEWPOINTS TO INCREASE THROUGHOUT THE DAY TO THE MID 40S BY LATE TONIGHT. ISENTROPIC CHARTS SHOW A STRONG ISENTROPIC COMPONENT WITHIN THE S/SE LOW AND MID LEVEL WINDS WHICH MAY LEAD TO INCREASING CLOUDS THROUGH THE AFTERNOON HOURS...HOWEVER CONDENSATION PRESSURE DEFICITS LOOK TO REMAIN TOO HIGH TO PRODUCE ANY PRECIPITATION UNTIL LATER THIS EVENING. WITH THE MAIN AREA OF MID LEVEL ENERGY HANGING OFF TO THE WEST THE MAIN INFLUENCE FOR FRIDAY NIGHT PRECIP WILL BE THE STRONG ISENTROPIC COMPONENT. FORECAST SOUNDING CORROBORATE WHAT THE ISENTROPIC SURFACES SUGGEST...WHICH IS THAT THE COLUMN WILL HAVE SOME DRY AIR TO OVERCOME THROUGHOUT THE DAY ON FRIDAY. EVENTUALLY IT WILL OVERCOME THE DRY AIR AND PRECIP WILL BEGIN FRIDAY EVENING. PRECIP COVERAGE AND INTENSITY WILL INCREASE THROUGH THE NIGHT AS THE COLUMN BECOMES COMPLETELY SATURATED. BY LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING THE MID LEVEL TROUGH WILL BEGIN MOVING THROUGH THE AREA. THE EXTRA LARGE SCALE ASCENT SHOULD ALLOW FOR MORE EFFICIENT RAIN PROCESSES...CAUSING PERIODS OF MODERATE RAIN TO OCCUR THROUGH MID DAY ON SATURDAY. ALONG WITH THE BETTER LARGE SCALE ASCENT THE COOLER TEMPS ALOFT ASSOCIATED WITH THE LARGE TROUGH WILL ALLOW FOR SOME ELEVATED STEEP LAPSE RATES...MAKING ELEVATED CAPE LEVELS APPROACH 500 J/KG. AS A RESULT PERIODS OF THUNDERSTORMS WILL BE LIKELY LATE FRIDAY NIGHT THROUGH THE DAY ON SATURDAY. ALTHOUGH THE THUNDERSTORMS ARE NOT EXPECTED TO BE VIGOROUS THE MODEST CAPE ALONG WITH 40 TO 50 KTS OF 0-6 SHEAR IT IS POSSIBLE THAT AN ISOLATED CELL OR TWO COULD BECOME STRONG WITH PERHAPS A SEVERE HAIL REPORT OR TWO SATURDAY MORNING/AFTERNOON. AS THE SYSTEM PROGRESSES TO THE EAST MODELS SEEM TO AGREE ON THE PLACEMENT AND TIMING OF A DRY SLOT OF MID LEVEL AIR CUTTING OFF THE EFFICIENT PRECIP PROCESSES BY SATURDAY AFTERNOON/EVENING. THIS WILL LIKELY SPELL AN END TO THE MODERATE PRECIP...ALTHOUGH SOME LIGHT PRECIP MAY LINGER THROUGH LATE SATURDAY NIGHT. ACROSS THE NORTHERN COUNTIES THERE WILL REMAIN A CHANCE FOR SOME VERY LIGHT SNOW FALL SATURDAY NIGHT AS A WEAK TROWAL FORMS ACROSS CENTRAL NEBRASKA. GIVEN THAT THE REGION WILL EXPERIENCE SEVERAL DAYS IN A ROW OF ABOVE FREEZING TEMPERATURES AS WELL AS A WET GROUND FROM THE SATURDAY RAINFALL EXPECT SNOW ACCUMULATIONS TO BE TOUGH TO COME BY. PERHAPS A DUSTING OF SNOW WILL BE POSSIBLE ON GRASSY AND ELEVATED SURFACES...BUT EXPECT PAVED SURFACES TO STAY WET AS OPPOSED TO SNOW PACKED. BY SUNDAY AFTERNOON THE SYSTEM SHOULD MOVE OFF TO THE EAST ENDING ALL PRECIPITATIONS CHANCES. QPF FORECAST FOR THIS SYSTEM REMAINS A BIT CONSERVATIVE AS MODELS HAVE OVERDONE PRECIP AMOUNT IN RECENT SYSTEMS. ON THE LOWER END THIS SYSTEM SHOULD HAVE NO PROBLEM PRODUCING A QUARTER INCH OF PRECIPITATION AREA-WIDE...WITH PERHAPS A FEW ISOLATED AREAS GETTING A FULL INCH. MOST AREAS WILL LIKELY GET SOMEWHERE BETWEEN THOSE TWO VALUES IN LIQUID PRECIP BETWEEN FRIDAY NIGHT AND SUNDAY MORNING. MID RANGE AND EXTENDED FORECAST (MONDAY THROUGH THURSDAY)... A STRONG PUSH OF COLD AIR WILL FOLLOW THE SYSTEM THROUGH THE AREA AND TO THE EAST. THIS PUSH OF COLD AIR WILL LIKELY BRING A COOL DOWN FOR SUNDAY AND MONDAY BEFORE SOUTHERLY FLOW RECOMMENCES...BRINGING WARM/MOIST AIR BACK INTO THE AREA. FOR A FEW DAYS NOW MODELS HAVE SHOWN THAT THE AREA WILL STAY DRY THROUGH NEXT WORK WEEK WITH A GRADUAL...BUT NOTICEABLE WARM UP. WITH A MID LEVEL RIDGE OFF TO THE WEST...GRADUALLY CREEPING EASTWARD THROUGH THE WEEK AND MOSTLY PERSISTENT SOUTHERLY FLOW EXPECT TUESDAY THROUGH THURSDAY TO BRING ABOVE SEASONALLY NORMAL TEMPERATURES. JL && .AVIATION... STILL SOME OPPORTUNITY FOR LIMITING CEILINGS LATER IN THIS FORECAST...BUT APPEARS TOP AND FOE SHOULD HOLD OFF UNTIL AFTER 06Z. ENOUGH WINDS SAMPLED BY RADARS AND PROFILERS TO SUPPORT LLWS MENTION TO START THIS FORECAST. CHANCES FOR SHRA INCREASE AT THE END OF THE FORECAST. 65 && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS BISMARCK ND
854 AM CST FRI MAR 8 2013 .DISCUSSION...LATST BOWMAN RADAR SHOWS AN AREA OF PRECIPITATION APPROACHING FROM THE SOUTH. THE LATEST RAP CAPTURES THIS AREA AND PUSHES IT ACROSS THE SOUTHWEST FROM 15Z THROUGH MID AFTERNOON. HAVE INCREASED POPS TO LIKELY IN THIS AREA. DENSE FOG FROM JAMESTOWN TO OAKES THIS MORNING SHOULD CONTINUE TO ERODE QUICKLY THIS MORNING AS THE JAMESTOWN WEB CAMS SEEM TO BE IMPROVING. WILL HOLD OFF ON ANY ADVISORY FOR NOW UNLESS CONDITIONS APPEAR TO LINGER LONGER THAN EXPECTED. OTHER CONCERN FOR THE SHORT TERM PERIOD WILL BE THE FAR SOUTHEAST COUNTIES TONIGHT AND SATURDAY...AS AN UPPER LOW NOW OVER SOUTHERN CALIFORNIA EJECTS NORTHEAST WITH ITS ATTENDANT PRECIPITATION. WILL LOOK MORE INTO THIS WITH THE 12Z DATA. && .AVIATION...DENSE FOG/VLIFR VSBYS AT KJMS WILL GRADUALLY LIFT TO MVFR VSBYS BY MID TO LATE MORNING...THEN VFR THIS AFTERNOON. OTHERWISE...EXPECT MAINLY MID LEVEL CLOUDS SCATTERED MVFR VSBYS THIS MORNING. WINDS WILL GENERALLY BECOME LIGHT AND VARIABLE AS HIGH PRESSURE BUILDS INTO THE REGION. AN APPROACHING DISTURBANCE WILL GENERATE A CHANCE FOR PRECIPITATION MAINLY SOUTH LATE THIS AFTERNOON AND EVENING...WITH CHANCES TO THE NORTH LATER TONIGHT. MVFR CIGS AND/OR VSBYS ARE LIKELY AGAIN TONIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION/AVIATION...KS/RK
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
859 AM MST FRI MAR 8 2013 .UPDATE... ISSUED AT 853 AM MST FRI MAR 8 2013 15Z SURFACE ANALYSIS HAD A WEAK COLD FRONT ACROSS MT INTO SOUTHERN ND. WATER VAPOUR HAD LARGE UPPER TROUGH WITH UPPER LOW DIGGING INTO SOUTHERN CA. SOUTHWEST FLOW ALOFT AHEAD OF SYSTEM PRODUCING STREAM OF MID/HIGH CLOUDS OVER THE CWA. EMBEDDED SHORTWAVE OVER SOUTHEAST MT...UNDER RIGHT ENTRANCE REGION OF 90KT JET...PRODUCING SOME WEAK RADAR RETURNS OVER NORTHWEST SD. AREA ALSO IN A REGION OF WEAK LOW LEVEL FRONTOGENESIS...WHICH SHOULD PERSIST MOST OF THE DAY PER 12Z RAP AND THUS WILL CONTINUE LOW POPS IN FAR NORTHWEST PORTIONS OF CWA. PRESSURE FALLS OVER EASTERN WY/MT SUPPORTING EAST/SOUTHEAST LOW LEVEL FLOW AND SOME FOG OVER PORTIONS OF CENTRAL SD. FOG SHOULD MIX AWAY SOME BY EARLY AFTERNOON...SO HAVE EXPANDED AND EXTENDED CURRENT AREA OF FOG TO COVER SOUTHEAST THIRD OF THE CWA. FINALLY...12Z NAM CONTINUES TREND OF FASTER NORTHERN STREAM TROUGH...WHICH WILL PUSH CA TROUGH FURTHER SOUTH AND EAST OF CWA. HAVE ADJUSTED POPS TO MATCH SLOWER ONSET OF PRECIPITATION THIS EVENING. && .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 351 AM MST FRI MAR 8 2013 DIGGING SW CONUS UPPER TROUGH WILL EJECT TOWARD THE REGION IN THE PERIOD AND SUPPORT CYCLOGENESIS OVER THE CENTRAL PLAINS. MEANWHILE A FAST MOVING NORTHERN STREAM TROUGH WILL DROP INTO THE NORTHERN PLAINS JUST AHEAD OF THE SW CONUS TROUGH...EVENTUALLY PHASING EAST OF THE REGION. FORECAST MODELS HAVE STRUGGLED WITH FORECAST DETAILS FOR THE LAST SEVERAL RUNS...KEEPING THE TRACK WELL SOUTH OF THE FA AT FIRST/THEN SHIFTING THE TRACK NW FOR SEVERAL CYCLES /WITH THE LATEST SUITE SUPPORTING A SHIFT BACK TO THE SOUTH. THE EXACT TRACK WILL HINGE UPON TWO MAIN FEATURES: 1/ HOW FAST THE NORTHERN STREAM TROUGH PROPAGATES INTO THE NORTHERN PLAINS AHEAD OF THE EJECTING SW CONUS UPPER TROUGH. 2/ THE INTENSITY OF THE FORWARD FLANK JET STREAK WHICH WILL DETERMINE THE DEGREE OF POSITIVE TROUGH TILT AND ASSOCIATED SHEARING OF THE THE SW CONUS UPPER WAVE...HIGHLY AFFECTING THE SPEED AND LIFT PLACEMENT. CURRENT TRENDS SUPPORT A STRONGER POSITIVE TILT TO THE SW CONUS UPPER WAVE...WITH A ASSOCIATED FASTER PROPAGATION SPEED...BRINGING IN A VERSION OF STRONGER SUBSIDENCE...WITH ASSOCIATED LL DRYING OVER MUCH OF THE WESTERN 2/3 OF THE FA SAT. IN ADDITION..LL THERMAL FIELDS HAVE TRENDED SLIGHTLY WARMER IN THE LATEST CONSENSUS BLEND...WITH MANY LOCATIONS EXPECTED TO BE WELL IN THE 30S AND EVEN LOWER 40S ON SAT...SAVE FAR SOUTH CENTRAL WHERE THE STRONGER COLLOCATION OF DEEP LAYER LIFT WILL BE PRESENT. THE POTENTIAL FOR MIXED PRECIP WITH A PERIOD OF FREEZING RAIN EXISTS OVER SCENTRAL LATE TONIGHT INTO SAT MORNING...ALTHOUGH AS STATED EARLIER...FORECAST MODELS HAVE TERNED WARMER PER THERMAL FIELDS...WITH LOCATIONS INVOF ICR REMAINING ABOVE FREEZING UNTIL SAT MORNING. ACCUMULATING SNOWFALL LOOKS TO REMAIN CONFINED TO THE FAR SOUTH AND SCENTRAL FA...WITH STRONG INDICATIONS REMAIN FOR POTENTIAL DEFORMATION BANDING OVER FAR SCENTRAL SAT AFTERNOON...A SOLUTION INDICATED IN NAM/GFS/SREF/AND ECMWF SOLUTIONS. QUESTION REMAINS THROUGH WHERE AND THIS BAND WILL SETUP AND THE DEGREE OF LL MOISTURE IN PLACE WHEN THE STRONGEST ROUND OF DEEP ASCENT DEVELOPS IN THAT LOCATION. LINGERING WEAK WAA/DEFORMATION ZONE WILL CONTINUE TO SHIFT NORTH OUT OF THE FA THIS MORNING...WITH ONLY SMALL CHANCES FOR PRECIP GIVEN WEAK FORCING AND DRY LL/S. OTHERWISE...THE NEXT ROUND OF STRONG WAA WILL ENSUE THIS EVENING OVER SOUTHERN PORTIONS OF THE FA...SPREADING NORTH OVERNIGHT. IT IS ENTIRELY POSSIBLE THAT THE MAJORITY OF PRECIP MAY BE CONFINED TO THE FAR SE PORTION OF THE FA...WITH MUCH UNCERTAINTY REMAINING PER THE DETAILS OF THE THIS FIRST ROUND OF WAA. RETAINED A MIXED POTENTIAL FOR THIS IN SE...WITH GENERAL RAIN CHANGING TO SNOW CHANCES ELSEWHERE. NORTHERN STREAM TROUGH WILL DIVE IN THE NORTHERN PLAINS AND SUPPORT A ROUND OF LARGE SCALE SINK OVER MUCH OF THE FA SAT...SUPPORTING LL DRYING OVER MUCH OF THE FA. DID TREND POPS DOWN AND TO THE SOUTH GIVEN THIS CONCERN. OTHERWISE...INCREASING LARGE SCALE ASCENT INDICATED IN Q-VECTOR PROGS IS EXPECTED OVER THE SOUTHERN PORTIONS OF THE FA...MAINLY SOUTH AND EAST OF A PINE RIDGE TO KADOKA LINE LATE SAT MORNING. ASSOCIATED LIFT MAY CONTINUE TO SUPPORT MIXED PRECIP. HOWEVER...DEEP AND STRONG ASCENT WILL LIKELY SUPPORT ENOUGH DYNAMIC COOLING TO SUPPORT ALL SNOW OVER SCENTRAL AREAS BY MID MORNING. OTHERWISE...THE REMAINDER THE FA MAY NOT SEE MUCH IN THE WAY OF PRECIP GIVEN STRONG SINK AND DRYING LL/S. THIS INCLUDES THE NORTHERN HILLS WHERE MOISTURE LOOKS TO BE LIMITED. THE NAM CERTAINLY DISPLAYS A SHARP CUT OFF TO PRECIP IN QPF PROGS WHICH LOOKS HIGHLY CREDIBLE. A RATHER WARM BL MAY LIMIT ACCUMS OVER PORTIONS OF THE SOUTHERN FA...HOWEVER THE POTENTIAL FOR UP TO 4 INCHES REMAIN OVER THE FAR SE...MELLETTE/TODD/TRIPP COUNTIES...WITH A LIKELY HEAVY WET LOWER RATIO SNOW BEING FAVORED. TRIED TO INCORPORATED A SHIFT OF THE HIGHEST POPS SE...LOWERING THE NW. WILL CONTINUE THE SPS AS DETAILS ARE STILL LACKING AND WARNING CRITERIA NOT EXPECTED. STRONG GUSTY NW WINDS ARE ALSO EXPECTED SAT AFTERNOON...ESP ON THE EASTERN BH FOOTHILLS. HOWEVER...WARM BL TEMPS ABOVE FREEZING MAY HIGHLY LIMIT BLOWING SNOW POTENTIAL. UPPER TROUGH AND ASSOCIATED LIFT WILL QUICKLY SHIFT EAST AND WANE OVER THE FA SAT EVENING...WITH ALL PLACES DRY AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 351 AM MST FRI MAR 8 2013 TEMPERATURES WILL GRADUALLY WARM INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE WESTERN CONUS. A VARIETY OF WEAK DISTURBANCES MOVING THROUGH WILL BRING LOW PRECIP CHANCES TO PTNS OF THE AREA THROUGH THE FIRST PART OF THE WEEK. RIDGE CONTINUES TO AMPLIFY OVER THE AREA FOR THE LAST PART OF THE WORK WEEK BRINGING DRY CONDITIONS AND WARM TEMPS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 351 AM MST FRI MAR 8 2013 ISOLD RAIN OR SNOW SHOWERS MAY LINGER OVER NORTHEAST WYOMING INTO NORTHWEST SOUTH DAKOTA TODAY BRINGING LCL MVFR CIGS/VIS. FOR TONIGHT...RAIN TRANSITIONING TO SNOW WILL DEVELOP OVER THE AREA...WITH THE GREATEST CHANCES OVER SOUTH CENTRAL SOUTH DAKOTA WHERE SOME FREEZING RAIN MAY ALSO DEVELOP. WIDESPREAD IFR CIGS WITH AREAS OF IFR VIS ARE EXPECTED OVER MUCH OF THE AREA. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...77 AVIATION...77
AREA FORECAST DISCUSSION...UPDATED
NWS FORT WORTH TX
549 AM CST FRI MAR 8 2013 .AVIATION... CHALLENGES FOR THE 12Z TAF SET INCLUDE CIG TRENDS BETWEEN MVFR AND LOW VFR AND TIMING OF RAIN CHANCES WITH A LEAD DISTURBANCE THIS AFTERNOON. STRATO-CU IN THE MVFR/VERY LOW VFR RANGE HAS BEEN SURGING NORTH ACROSS THE TERMINALS IN ADVANCE OF A LEAD SHORTWAVE DISTURBANCE ROTATING NORTHEAST OUT OF OLD MEXICO AND THE RIO GRANDE VALLEY. THOUGH THERE MAY BE A BRIEF WINDOW FOR LOW VFR CIGS BETWEEN 030-040 THIS MORNING...WILL LEAN WITH MODEL BUFR AND RUC OPS40 SOUNDINGS WITH GOING WITH A PREVAILING MVFR AROUND 025...BUT WITH A TEMPO GROUP FOR LOW MVFR CIGS BETWEEN 015-020 THROUGH LATE MORNING. ISENTROPIC ASCENT THIS AFTERNOON SHOULD HELP TOP-DOWN COLUMN SATURATION OCCUR QUICKLY AND SOME -RA/-SHRA OCCURRING BETWEEN 21Z AND 01Z. HAVE INTRODUCED A PROB30 GROUP TO COVER THIS VERY LIGHT RAINFALL THAT IS EXPECTED THIS AFTERNOON. THE LEAD SHORTWAVE EXITS TO THE NORTHEAST EARLY THIS EVENING WITH A BRIEF WINDOW FOR CIGS IMPROVING TO LOW VFR ONCE AGAIN...BEFORE RETURNING TO THE MVFR CATEGORY BY MIDNIGHT AND BEYOND. SOUTHEAST WINDS 10-15 KTS WILL CONTINUE THROUGHOUT THE FORECAST. OUTLOOK... MODELS HAVE SPED UP TIMING OF DRYLINE/FRONT IN ADVANCE OF OUR MAIN SYSTEM ROTATING SOUTHEAST CURRENTLY OVER SRN CA/WRN AZ. IT APPEARS THE MAIN WINDOW FOR +TSRA WILL BE 21Z-03Z SATURDAY WITH WINDS SHIFTING NORTHWEST AND VERY GUSTY BEHIND THE COLD FRONT BY 12Z SUNDAY. 05/ && .PREV DISCUSSION... /ISSUED 313 AM CST FRI MAR 8 2013/ 0UR NEXT UPPER STORM SYSTEM WILL BE MOVING INTO SOUTHERN CALIFORNIA THIS MORNING WITH CYCLOGENESIS UNDERWAY ALONG THE FRONT RANGE OF COLORADO. THE UPPER LOW WILL MOVE REACH THE 4-CORNERS SATURDAY MORNING AND KANSAS BY SATURDAY EVENING. A TROUGH EXTENSION WILL HANG BACK INTO SOUTHERN ARIZONA AS THE MAIN UPPER LOW CONTINUES INTO THE MIDWEST. SATURDAY THROUGH SATURDAY NIGHT...THE 300MB JET WILL BE INCREASING FROM LESS THAN 60 KNOTS IN THE MORNING TO 90-100KTS IN THE EVENING WHICH WILL HELP TO INCREASE 0-6KM BULK SHEAR INTO THE 60-70 KNOTS RANGE. BEST CAPE VALUES...300-600 J/KG...WILL OCCUR OVER THE SOUTHWEST AND WESTERN COUNTIES SATURDAY AFTERNOON WHICH SHOULD BE WHERE THE STRONGEST...POSSIBLY SEVERE... STORMS OCCUR WITH THIS SYSTEM LATE SATURDAY AFTERNOON. ALTHOUGH SHEAR REMAINS HIGH SATURDAY EVENING AND OVERNIGHT...WEAKENING INSTABILITY AND MID LEVEL LAPSE RATES SHOULD RESULT IN A DIMINISHED CHANCE OF SEVERE STORMS BY MID EVENING SATURDAY. AS THE PACIFIC PUSHES THROUGH THE CWA SATURDAY NIGHT...THE LINE OF STORMS COULD PRODUCE RAINFALL OF 1/2 TO 1 INCH WITH THE SOUTHEAST THIRD HAVING THE BEST CHANCE TO SEE 3/4 TO OVER 1 INCH BEFORE ENDING. ON SUNDAY...THE REMAINING UPPER TROUGH TO OUR WEST WILL SLIDE ACROSS THE REGION...AND MAY PRODUCE SOME LIGHT RAIN FROM LINGERING MID LEVEL MOISTURE...BUT AMOUNTS WILL BE LIGHT. COLDER AIR ARRIVES BEHIND THE FRONT FOR THE FIRST OF THE WORK WEEK. THE WESTERN AND NORTHERN AREAS MAY SEE A FREEZE ON TUESDAY MORNING. THE REST OF NEXT WEEK WILL BE DRY WITH TEMPERATURES MODERATING TO ABOVE NORMAL. 75 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 65 57 68 50 58 / 30 20 30 80 20 WACO, TX 67 58 69 51 58 / 20 20 30 70 60 PARIS, TX 63 53 66 52 58 / 20 20 20 70 40 DENTON, TX 65 58 68 48 57 / 40 20 30 80 20 MCKINNEY, TX 65 56 67 49 58 / 30 20 30 80 30 DALLAS, TX 67 57 68 52 58 / 30 20 30 80 30 TERRELL, TX 65 55 67 53 58 / 20 20 30 70 40 CORSICANA, TX 66 57 69 55 59 / 20 20 20 70 60 TEMPLE, TX 67 59 70 53 59 / 20 20 20 70 70 MINERAL WELLS, TX 66 59 71 47 57 / 40 20 40 60 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/75
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1040 AM MST FRI MAR 8 2013 .UPDATE... ISSUED AT 1034 AM MST FRI MAR 8 2013 I AMENDED THE BLIZZARD WARNING TEXT TO INDICATE THAT THE SNOW WILL LIKELY START DURING THE 6 AM TO 8 AM TIME FRAME...AND THE WINDS INITIALLY WILL NOT BE ALL THAT STRONG. HOWEVER AS THE MORNING PROGRESSES WINDS WILL STEADILY INCREASE AND WILL BE GUSTING TO BLIZZARD CRITERIA BY NOON-ISH. FWIW...RAW GFS WINDS AT 00Z SUNDAY SHOW NORTH WINDS SUSTAINED AT 42 KNOTS OVER NE EL PASO COUNTY. GIVEN THIS...POWER OUTAGES WILL BE POSSIBLE DUE TO DOWNED POWER POLES/WIRES. THE WORST OF THE CONDITIONS SHOULD LAST FOR ABOUT 12-15 HOURS. I ADDED EASTERN LAS ANIMAS COUNTY INTO THE WINTER STORM WATCH. THIS WATCH IS IN EFFECT SAT AFTERNOON AND EVENING. LATEST GUIDANCE INDICATES STRONG WINDS AND PERIODS OF HEAVY SNOW WILL BE POSSIBLE THIS REGION. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 506 AM MST FRI MAR 8 2013 CLOUDS ARE INCREASING OVR WRN CO THIS MORNING AHEAD OF THE UPPER LEVEL LOW THAT SATELLITE IMAGES SHOW OFF THE SRN CA COAST. A THICK BAND OF CLOUDS HAS ALSO MOVED UP OVR THE SERN CORNER OF THE STATE...BUT THAT SHOULD PUSH EAST LATER THIS MORNING. BY EVENING THE UPR LOW CENTER IS EXPECTED TO MOVE OVR THE CA AND AZ BORDER AREA. BOTH THE HRRR AND NAM12 SHOWING PCPN HOLDING OFF OVR THE SWRN MTS UNTIL AT LEAST LATE MORNING...BUT THEN WE SHOULD SEE PCPN ALL ALONG THE CONTDVD THIS AFTERNOON...WITH SCT TO LIKELY POPS SPREADING OVR MUCH OF THE ERN MTS AS WELL AND OVR THE SAN LUIS VALLEY...AND MAINLY ISOLD CHANCE FOR RAIN OVR THE SERN PLAINS. FOR THIS AFTERNOON THE NAM IS SHOWING A FEW HUNDRED JOULES OF CAPES OVR THE MTS AND PORTIONS OF THE I-25 CORRIDOR...WITH LAPSE RATES OF 8-9C/KM OVR THE FORECAST AREA. WL GO WITH SOME ISOLD THUNDERSTORMS CHANCES THIS AFTERNOON AND EARLY EVENING. FOR THIS AFTERNOON THE EASTERN SAN JUAN MTS SHOULD BE THE AREA THAT RECEIVES THE HEAVIEST SNOW...WITH THE REST OF THE CONTDVD SEEING SNOW...BUT NOT AS MUCH. DURING THE AFTERNOON SOME STRONG SOUTHERLY WINDS ARE EXPECTED TO DEVELOP OVR THE FAR SERN CORNER OF THE STATE WITH GUSTS OF 30-40 MPH. MIN RH VALUES IN THIS AREA ARE EXPECTED TO BE NR 15 PERCENT. HOWEVER FUELS IN THIS AREA ARE NOT CONSIDERED TO BE CRITICAL. HAVE ISSUED A WINTER WX ADVISORY FOR ZONE 67 AS WELL AND WL START IT IN THE LATE AFTERNOON TODAY. TEMPS IN THE EARLY AFTERNOON WL LIKELY BE TOO WARM TO SEE SNOW OR AT LEAST ANY REAL ACCUMULATIONS UNTIL TEMPS COOL TOWARD EVENING AND OVERNIGHT. BY 12Z SAT THE UPR LOW CENTER IS EXPECTED TO MOVE INTO THE SW CORNER OF CO. AS THIS OCCURS OVERNIGHT A DRY SLOT DEVELOPS OVR THE SERN PLAINS...AND SHOULD SEE DECREASING CHANCES FOR PCPN OVR THE SAN LUIS VALLEY AND SERN MTS. AT THE SAME TIME SNOW WL CONTINUE ALONG THE CONTDVD WITH THE EASTERN SAN JUAN MTS STILL BEING THE MOST FAVORED LOCATION FOR SIGNIFICANT SNOWFALL. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 506 AM MST FRI MAR 8 2013 ...QUICK MOVING STORM TO BRING SNOW AND BLOWING SNOW TO THE AREA SATURDAY... SATURDAY-SATURDAY NIGHT...LATEST MODELS REMAIN IN GOOD AGREEMENT OF A POTENT UPPER LOW ACROSS THE SOUTHERN CALIFORNIA COAST THIS MORNING LIFTING OUT INTO THE FOUR CORNERS REGION LATE TONIGHT WHICH THEN CONTINUES TO TRANSLATE ACROSS SOUTHERN COLORADO THROUGH THE DAY SATURDAY AND INTO NORTHWESTERN KANSAS SATURDAY NIGHT. MOVEMENT OF THIS SYSTEM KEEPS MODERATE TO HEAVY SNOWFALL ACROSS THE CONTDVD FRIDAY NIGHT AND SATURDAY WITH DEFORMATION BAND PRECIPITATION SPREADING EAST ACROSS SOUTH CENTRAL COLORADO AND THE EASTERN MTS SATURDAY MORNING AND AFTERNOON. MODELS REMAIN CONSISTENT WITH STRONG NORTHERLY WINDS DEVELOPING ACROSS THE EASTERN PLAINS LATE SATURDAY MORNING AND PERSISTING THROUGH THE EARLY EVENING AS AN ASSOCIATED COLD FRONT BLASTS ACROSS THE PLAINS. PRECIPITATION TYPE STILL IN QUESTION ACROSS THE PLAINS THOUGH MODEL SOUNDINGS INDICATING PRECIP RAPIDLY CHANGING OVER THE SNOW AOA 6K FT SATURDAY MORNING AND POSSIBLY LOWERING TO 4K FT UNDER THE HEAVIER BANDS AS THE SYSTEM LIFTS OUT ACROSS THE EASTERN PLAINS SATURDAY AFTERNOON AND EVENING. WITH THAT SAID...HAVE UPGRADED WINTER STORM WATCH TO A BLIZZARD WARNING FOR NORTHERN EL PASO COUNTY WITH 4-9 INCHES ALONG WITH STRONG NORTHERLY WINDS UP TO 30 MPH GUSTING TO NEAR 50 MPH AT TIMES...ESPECIALLY SATURDAY AFTERNOON. HAVE ALSO UPGRADED TELLER COUNTY AND THE RAMPART RANGE TO WINTER STORM WARNING WITH AMOUNTS RANGING FROM 6 TO 12 INCHES AND HAVE ISSUED WINTER WEATHER ADVISORIES FOR LAKE COUNTY...THE WESTERN MOSQUITO RANGE BELOW 9000 FEET AND NORTHWESTERN FREMONT COUNTY ABOVE 8500 FEET. HAVE ALSO ISSUED A WINTER STORM WATCH FOR THE SANGRE DE CRISTO AND WET MTS FROM SATURDAY MORNING THROUGH SATURDAY NIGHT. GFS IS STILL A BIT HEAVY HANDED WITH AMOUNTS ACROSS THE SOUTHEAST MTS AS WELL AS UNDER THE BANDS AND WILL NEED TO CONTINUE TO MONITOR FOR POSSIBLE ADDITIONS TO ADVISORIES AND WARNINGS. SUNDAY-WEDNESDAY...MODEL CONSENSUS CONTINUES TO INDICATE WARMER AND DRY CONDITIONS ACROSS THE AREA THROUGH THE REST OF EXTENDED PERIOD WITH MODERATE WESTERLY FLOW ACROSS THE REGION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 506 AM MST FRI MAR 8 2013 EXPECTED VFR CONDITIONS AT KPUB AND KCOS TODAY AND TONIGHT. LATE THIS AFTERNOON AND THIS EVENING THERE COULD BE A FEW SHOWERS OR EVEN A THUNDERSTORM AT OR IN THE VCNTY. KALS SHOULD HAVE VFR CONDITIONS BUT LATE THIS AFTERNOON SOME SHOWERS OR EVEN A THUNDERSTORM COULD RESULT IN BRIEF MVFR CONDITIONS. THERE IS ALSO THE POSSIBILITY OF SOME STRATUS OR BR TOWARD MORNING CAUSING MVFR CONDITIONS...ALTHOUGH CONFIDENCE IN THIS OCCURRING IT TOO LOW TO INCLUDE IN THE TAF AT THIS TIME. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM MST SATURDAY FOR COZ059-063-076. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR COZ072>075-079-080. WINTER STORM WARNING UNTIL 11 PM MST SATURDAY FOR COZ058-060. WINTER STORM WATCH FROM SATURDAY AFTERNOON THROUGH SATURDAY EVENING FOR COZ094. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 5 PM MST SATURDAY FOR COZ067. WINTER STORM WARNING UNTIL 8 PM MST SATURDAY FOR COZ066-068. WINTER STORM WARNING FROM 5 AM TO 8 PM MST SATURDAY FOR COZ081- 082. BLIZZARD WARNING FROM 5 AM TO 8 PM MST SATURDAY FOR COZ084. && $$ UPDATE...HODANISH SHORT TERM...28 LONG TERM...MW AVIATION...28
AREA FORECAST DISCUSSION
NWS PUEBLO CO
1036 AM MST FRI MAR 8 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 506 AM MST FRI MAR 8 2013 CLOUDS ARE INCREASING OVR WRN CO THIS MORNING AHEAD OF THE UPPER LEVEL LOW THAT SATELLITE IMAGES SHOW OFF THE SRN CA COAST. A THICK BAND OF CLOUDS HAS ALSO MOVED UP OVR THE SERN CORNER OF THE STATE...BUT THAT SHOULD PUSH EAST LATER THIS MORNING. BY EVENING THE UPR LOW CENTER IS EXPECTED TO MOVE OVR THE CA AND AZ BORDER AREA. BOTH THE HRRR AND NAM12 SHOWING PCPN HOLDING OFF OVR THE SWRN MTS UNTIL AT LEAST LATE MORNING...BUT THEN WE SHOULD SEE PCPN ALL ALONG THE CONTDVD THIS AFTERNOON...WITH SCT TO LIKELY POPS SPREADING OVR MUCH OF THE ERN MTS AS WELL AND OVR THE SAN LUIS VALLEY...AND MAINLY ISOLD CHANCE FOR RAIN OVR THE SERN PLAINS. FOR THIS AFTERNOON THE NAM IS SHOWING A FEW HUNDRED JOULES OF CAPES OVR THE MTS AND PORTIONS OF THE I-25 CORRIDOR...WITH LAPSE RATES OF 8-9C/KM OVR THE FORECAST AREA. WL GO WITH SOME ISOLD THUNDERSTORMS CHANCES THIS AFTERNOON AND EARLY EVENING. FOR THIS AFTERNOON THE EASTERN SAN JUAN MTS SHOULD BE THE AREA THAT RECEIVES THE HEAVIEST SNOW...WITH THE REST OF THE CONTDVD SEEING SNOW...BUT NOT AS MUCH. DURING THE AFTERNOON SOME STRONG SOUTHERLY WINDS ARE EXPECTED TO DEVELOP OVR THE FAR SERN CORNER OF THE STATE WITH GUSTS OF 30-40 MPH. MIN RH VALUES IN THIS AREA ARE EXPECTED TO BE NR 15 PERCENT. HOWEVER FUELS IN THIS AREA ARE NOT CONSIDERED TO BE CRITICAL. HAVE ISSUED A WINTER WX ADVISORY FOR ZONE 67 AS WELL AND WL START IT IN THE LATE AFTERNOON TODAY. TEMPS IN THE EARLY AFTERNOON WL LIKELY BE TOO WARM TO SEE SNOW OR AT LEAST ANY REAL ACCUMULATIONS UNTIL TEMPS COOL TOWARD EVENING AND OVERNIGHT. BY 12Z SAT THE UPR LOW CENTER IS EXPECTED TO MOVE INTO THE SW CORNER OF CO. AS THIS OCCURS OVERNIGHT A DRY SLOT DEVELOPS OVR THE SERN PLAINS...AND SHOULD SEE DECREASING CHANCES FOR PCPN OVR THE SAN LUIS VALLEY AND SERN MTS. AT THE SAME TIME SNOW WL CONTINUE ALONG THE CONTDVD WITH THE EASTERN SAN JUAN MTS STILL BEING THE MOST FAVORED LOCATION FOR SIGNIFICANT SNOWFALL. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 506 AM MST FRI MAR 8 2013 ...QUICK MOVING STORM TO BRING SNOW AND BLOWING SNOW TO THE AREA SATURDAY... SATURDAY-SATURDAY NIGHT...LATEST MODELS REMAIN IN GOOD AGREEMENT OF A POTENT UPPER LOW ACROSS THE SOUTHERN CALIFORNIA COAST THIS MORNING LIFTING OUT INTO THE FOUR CORNERS REGION LATE TONIGHT WHICH THEN CONTINUES TO TRANSLATE ACROSS SOUTHERN COLORADO THROUGH THE DAY SATURDAY AND INTO NORTHWESTERN KANSAS SATURDAY NIGHT. MOVEMENT OF THIS SYSTEM KEEPS MODERATE TO HEAVY SNOWFALL ACROSS THE CONTDVD FRIDAY NIGHT AND SATURDAY WITH DEFORMATION BAND PRECIPITATION SPREADING EAST ACROSS SOUTH CENTRAL COLORADO AND THE EASTERN MTS SATURDAY MORNING AND AFTERNOON. MODELS REMAIN CONSISTENT WITH STRONG NORTHERLY WINDS DEVELOPING ACROSS THE EASTERN PLAINS LATE SATURDAY MORNING AND PERSISTING THROUGH THE EARLY EVENING AS AN ASSOCIATED COLD FRONT BLASTS ACROSS THE PLAINS. PRECIPITATION TYPE STILL IN QUESTION ACROSS THE PLAINS THOUGH MODEL SOUNDINGS INDICATING PRECIP RAPIDLY CHANGING OVER THE SNOW AOA 6K FT SATURDAY MORNING AND POSSIBLY LOWERING TO 4K FT UNDER THE HEAVIER BANDS AS THE SYSTEM LIFTS OUT ACROSS THE EASTERN PLAINS SATURDAY AFTERNOON AND EVENING. WITH THAT SAID...HAVE UPGRADED WINTER STORM WATCH TO A BLIZZARD WARNING FOR NORTHERN EL PASO COUNTY WITH 4-9 INCHES ALONG WITH STRONG NORTHERLY WINDS UP TO 30 MPH GUSTING TO NEAR 50 MPH AT TIMES...ESPECIALLY SATURDAY AFTERNOON. HAVE ALSO UPGRADED TELLER COUNTY AND THE RAMPART RANGE TO WINTER STORM WARNING WITH AMOUNTS RANGING FROM 6 TO 12 INCHES AND HAVE ISSUED WINTER WEATHER ADVISORIES FOR LAKE COUNTY...THE WESTERN MOSQUITO RANGE BELOW 9000 FEET AND NORTHWESTERN FREMONT COUNTY ABOVE 8500 FEET. HAVE ALSO ISSUED A WINTER STORM WATCH FOR THE SANGRE DE CRISTO AND WET MTS FROM SATURDAY MORNING THROUGH SATURDAY NIGHT. GFS IS STILL A BIT HEAVY HANDED WITH AMOUNTS ACROSS THE SOUTHEAST MTS AS WELL AS UNDER THE BANDS AND WILL NEED TO CONTINUE TO MONITOR FOR POSSIBLE ADDITIONS TO ADVISORIES AND WARNINGS. SUNDAY-WEDNESDAY...MODEL CONSENSUS CONTINUES TO INDICATE WARMER AND DRY CONDITIONS ACROSS THE AREA THROUGH THE REST OF EXTENDED PERIOD WITH MODERATE WESTERLY FLOW ACROSS THE REGION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1017 AM MST FRI MAR 8 2013 VFR CONDITIONS EXPECTED TODAY WITH SHOWERS MOVING OFF THE MOUNTAINS...POSSIBLY AFFECTING KALS AND KCOS IN THE AFTERNOON. WILL CONTINUE TO CARRY VCSH IN BOTH TAF SITES AFTER 21Z FOR KALS STARTING AROUND 00Z FOR KCOS. CIGS SHOULD STAY VFR WITH MAIN THREAT BEING GUSTY ERRATIC WINDS. MAIN BRUNT OF THE STORM WILL AFFECT KCOS AND KPUB AFTER 15Z-16Z ON SATURDAY WITH A BRISK WIND SHIFT OUT OF THE NORTH GUSTING TO 35-40 KTS BY 18Z OR SHORTLY AFTER. SNOW AND BLOWING SNOW WILL SPREAD IN QUICKLY BEHIND THE FRONT WITH DETERIORATING CONDITIONS WITH IFR CIGS AND EVEN PERIODS OF LIFR VIS WITH BLSN. WINDOW FOR BEST ACCUMULATING SNOW POTENTIAL WILL CONTINUE THROUGH 22Z SAT FOR KCOS AND THROUGH 23Z FOR KPUB...WITH ACCUMULATIONS OF 1-3 INCHES POSSIBLE FOR KCOS...AND GENERALLY UP TO AN INCH MAINLY ON GRASSY SURFACES FOR KPUB. STRONG NORTH WINDS WILL CONTINUE THROUGH THE EVENING...WITH BLSN POSSIBLE AT THE KCOS TERMINAL THROUGH 03Z. KALS MAY SEE A QUICK SHOT FOR -SHSN AND VFR TO MVFR CIGS/VIS SAT AFTERNOON...JUST OUTSIDE THE TAF FORECAST PERIOD. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 5 AM TO 5 PM MST SATURDAY FOR COZ059-063-076. WINTER STORM WATCH FROM SATURDAY MORNING THROUGH SATURDAY EVENING FOR COZ072>075-079-080. WINTER STORM WARNING UNTIL 11 PM MST SATURDAY FOR COZ058-060. WINTER WEATHER ADVISORY FROM 4 PM THIS AFTERNOON TO 5 PM MST SATURDAY FOR COZ067. WINTER STORM WARNING UNTIL 8 PM MST SATURDAY FOR COZ066-068. WINTER STORM WARNING FROM 5 AM TO 8 PM MST SATURDAY FOR COZ081- 082. BLIZZARD WARNING FROM 5 AM TO 8 PM MST SATURDAY FOR COZ084. && $$ SHORT TERM...28 LONG TERM...MW AVIATION...KT
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1202 PM CST FRI MAR 8 2013 ...UPDATE TO AVIATION... .DISCUSSION... SHORT RANGE FORECAST (TODAY THROUGH SATURDAY)... 09Z RAP ANALYSIS AND SURFACE OBS SHOW A TIGHTENING SURFACE PRESSURE GRADIENT TAKING FORM ACROSS THE AREA AS AN AREA OF LOW PRESSURE SITS OVER SE COLORADO. WATER VAPOR IMAGERY INDICATES THAT A MID TO UPPER LEVEL TROUGH CURRENTLY SITS OVER SOUTHERN CALIFORNIA...WITH A STRONG SOUTH/SOUTHWEST COMPONENT TO THE MID/UPPER WINDS WELL TO THE EAST OF THE TROUGH CENTER. WITHIN THIS MID LEVEL SOUTHERLY FLOW WATER VAPOR IMAGERY SHOWS SOME MOISTURE WORKING ITS WAY THROUGH THE SOUTHERN HIGH PLAINS INTO WESTERN KANSAS. THIS TROUGH WILL BE THE IMPETUS BEHIND RAIN CHANCES LATER TONIGHT THROUGH THE WEEKEND. AS THE SURFACE TROUGH TAKES FORM THE SURFACE PRESSURE GRADIENT WILL BECOME A BIT STRONGER ALLOWING FOR THE WINDS TO PICK UP THROUGHOUT THE DAY. EXPECT S/SE WINDS TO EVENTUALLY INCREASE TO BETWEEN 15 AND 25 MPH...WITH GUSTS UP TO 30. LOW LEVEL SOUTHERLY WINDS WILL ALSO TRANSPORT WARM/MOIST AIR INTO THE AREA. EXPECT DEWPOINTS TO INCREASE THROUGHOUT THE DAY TO THE MID 40S BY LATE TONIGHT. ISENTROPIC CHARTS SHOW A STRONG ISENTROPIC COMPONENT WITHIN THE S/SE LOW AND MID LEVEL WINDS WHICH MAY LEAD TO INCREASING CLOUDS THROUGH THE AFTERNOON HOURS...HOWEVER CONDENSATION PRESSURE DEFICITS LOOK TO REMAIN TOO HIGH TO PRODUCE ANY PRECIPITATION UNTIL LATER THIS EVENING. WITH THE MAIN AREA OF MID LEVEL ENERGY HANGING OFF TO THE WEST THE MAIN INFLUENCE FOR FRIDAY NIGHT PRECIP WILL BE THE STRONG ISENTROPIC COMPONENT. FORECAST SOUNDING CORROBORATE WHAT THE ISENTROPIC SURFACES SUGGEST...WHICH IS THAT THE COLUMN WILL HAVE SOME DRY AIR TO OVERCOME THROUGHOUT THE DAY ON FRIDAY. EVENTUALLY IT WILL OVERCOME THE DRY AIR AND PRECIP WILL BEGIN FRIDAY EVENING. PRECIP COVERAGE AND INTENSITY WILL INCREASE THROUGH THE NIGHT AS THE COLUMN BECOMES COMPLETELY SATURATED. BY LATE FRIDAY NIGHT INTO EARLY SATURDAY MORNING THE MID LEVEL TROUGH WILL BEGIN MOVING THROUGH THE AREA. THE EXTRA LARGE SCALE ASCENT SHOULD ALLOW FOR MORE EFFICIENT RAIN PROCESSES...CAUSING PERIODS OF MODERATE RAIN TO OCCUR THROUGH MID DAY ON SATURDAY. ALONG WITH THE BETTER LARGE SCALE ASCENT THE COOLER TEMPS ALOFT ASSOCIATED WITH THE LARGE TROUGH WILL ALLOW FOR SOME ELEVATED STEEP LAPSE RATES...MAKING ELEVATED CAPE LEVELS APPROACH 500 J/KG. AS A RESULT PERIODS OF THUNDERSTORMS WILL BE LIKELY LATE FRIDAY NIGHT THROUGH THE DAY ON SATURDAY. ALTHOUGH THE THUNDERSTORMS ARE NOT EXPECTED TO BE VIGOROUS THE MODEST CAPE ALONG WITH 40 TO 50 KTS OF 0-6 SHEAR IT IS POSSIBLE THAT AN ISOLATED CELL OR TWO COULD BECOME STRONG WITH PERHAPS A SEVERE HAIL REPORT OR TWO SATURDAY MORNING/AFTERNOON. AS THE SYSTEM PROGRESSES TO THE EAST MODELS SEEM TO AGREE ON THE PLACEMENT AND TIMING OF A DRY SLOT OF MID LEVEL AIR CUTTING OFF THE EFFICIENT PRECIP PROCESSES BY SATURDAY AFTERNOON/EVENING. THIS WILL LIKELY SPELL AN END TO THE MODERATE PRECIP...ALTHOUGH SOME LIGHT PRECIP MAY LINGER THROUGH LATE SATURDAY NIGHT. ACROSS THE NORTHERN COUNTIES THERE WILL REMAIN A CHANCE FOR SOME VERY LIGHT SNOW FALL SATURDAY NIGHT AS A WEAK TROWAL FORMS ACROSS CENTRAL NEBRASKA. GIVEN THAT THE REGION WILL EXPERIENCE SEVERAL DAYS IN A ROW OF ABOVE FREEZING TEMPERATURES AS WELL AS A WET GROUND FROM THE SATURDAY RAINFALL EXPECT SNOW ACCUMULATIONS TO BE TOUGH TO COME BY. PERHAPS A DUSTING OF SNOW WILL BE POSSIBLE ON GRASSY AND ELEVATED SURFACES...BUT EXPECT PAVED SURFACES TO STAY WET AS OPPOSED TO SNOW PACKED. BY SUNDAY AFTERNOON THE SYSTEM SHOULD MOVE OFF TO THE EAST ENDING ALL PRECIPITATIONS CHANCES. QPF FORECAST FOR THIS SYSTEM REMAINS A BIT CONSERVATIVE AS MODELS HAVE OVERDONE PRECIP AMOUNT IN RECENT SYSTEMS. ON THE LOWER END THIS SYSTEM SHOULD HAVE NO PROBLEM PRODUCING A QUARTER INCH OF PRECIPITATION AREA-WIDE...WITH PERHAPS A FEW ISOLATED AREAS GETTING A FULL INCH. MOST AREAS WILL LIKELY GET SOMEWHERE BETWEEN THOSE TWO VALUES IN LIQUID PRECIP BETWEEN FRIDAY NIGHT AND SUNDAY MORNING. MID RANGE AND EXTENDED FORECAST (MONDAY THROUGH THURSDAY)... A STRONG PUSH OF COLD AIR WILL FOLLOW THE SYSTEM THROUGH THE AREA AND TO THE EAST. THIS PUSH OF COLD AIR WILL LIKELY BRING A COOL DOWN FOR SUNDAY AND MONDAY BEFORE SOUTHERLY FLOW RECOMMENCES...BRINGING WARM/MOIST AIR BACK INTO THE AREA. FOR A FEW DAYS NOW MODELS HAVE SHOWN THAT THE AREA WILL STAY DRY THROUGH NEXT WORK WEEK WITH A GRADUAL...BUT NOTICEABLE WARM UP. WITH A MID LEVEL RIDGE OFF TO THE WEST...GRADUALLY CREEPING EASTWARD THROUGH THE WEEK AND MOSTLY PERSISTENT SOUTHERLY FLOW EXPECT TUESDAY THROUGH THURSDAY TO BRING ABOVE SEASONALLY NORMAL TEMPERATURES. JL && .AVIATION... VFR CONDITIONS EXPECTED THROUGH 00Z SATURDAY. VCTS EXPECTED AFTER 00Z WITH VFR CIGS THEN EXPECT MORE COVERAGE WITH SHOWERS AND ISOLATED THUNDERSTORMS AFTER 06Z THROUGH THE END OF THE PERIOD. FORECAST SOUNDINGS SUGGEST MVFR CIGS TO PREVAIL AFTER 12Z SATURDAY. WINDS CONTINUE OUT OF THE SOUTHEAST THROUGH THE PERIOD AROUND 12 TO 14 KTS. SOME GUSTS TO 20 KTS POSSIBLE THROUGH 00Z. 53 && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
437 PM EST FRI MAR 8 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 431 PM EST FRI MAR 8 2013 WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW SPLIT FLOW DOMINATING NAMERICA. IN THE SRN STREAM...POTENT LOOKING SHORTWAVE HAS MOVED ONSHORE OVER SRN CA WHILE ANOTHER WAVE IS DROPPING S OVER WRN OR/NRN CA. BOTH OF THESE WAVES WILL PLAY A ROLE IN THE WX ACROSS THE GREAT LAKES IN THE COMING DAYS. DOWNSTREAM OF THE WRN TROF...RIDGING IS OVER THE CNTRL CONUS. TO THE N...ONE SHORTWAVE IS TRACKING THRU NRN ONTARIO. ANOTHER WAVE IS DROPPING SE INTO ALBERTA ON THE PERIPHERY OF POLAR VORTEX CENTERED JUST N OF HUDSON BAY. THIS WAVE WILL ALSO PLAY A ROLE IN THE WX OVER THE GREAT LAKES IN THE COMING DAYS. CLOSER TO HOME...LOW CLOUDS HAVE LINGERED OVER THE ERN FCST AREA IN SRLY FLOW OFF LAKE MI. HOWEVER...RECENTLY...ONLY A SMALL AREA OF STRATOCU REMAINS...STREAMING ONSHORE IN SRN SCHOOLCRAFT COUNTY. ELSEWHERE...EARLY MARCH SUNSHINE IS DOING ITS JOB ON THE LOWER ALBEDO FORESTED LAND OF THE U.P. TEMPS HAVE PUSHED INTO THE 40S AT A NUMBER OF OBS SITES OVER WRN UPPER MI. IN THE SHORT TERM...QUIET WX TONIGHT WILL GIVE WAY TO INCREASING PCPN CHANCES SAT UNDER STRENGTHENING WAA REGIME AHEAD OF NRN STREAM WAVE THAT WILL BE MOVING INTO SRN MANITOBA/ND AND SRN STREAM WAVE EMERGING OVER THE SRN HIGH PLAINS. TONIGHT...SRLY FLOW WILL BE ON THE INCREASE AHEAD OF THE AFOREMENTIONED SHORTWAVES. THERE IS THE USUAL CONCERN UNDER SRLY FLOW THAT LOW CLOUDS MAY DEVELOP. IN THIS CASE...HOWEVER...THE NAM AND GFS SHOW DRY AIR ADVECTION TONIGHT AT THE LOW-LEVELS AS TRAJECTORIES STILL HAVE SUFFICIENT COMPONENT EMANATING FROM RETREATING HIGH PRES. SO...LOW CLOUDS MAY NOT REALLY BE AN ISSUE TONIGHT. IF ANY VERY LOW/SHALLOW STRATUS DOES DEVELOP... IT SHOULD ONLY BE IN THE AREAS WITH BEST UPSLOPING OVER CNTRL UPPER MI. OTHERWISE...EXPECT GENERALLY PARTLY CLOUDY SKIES IN THE EVENING...AND THEN AN INCREASE IN HIGH CLOUDS OVERNIGHT. TYPICAL FOR THIS TYPE OF INITIALLY RATHER WEAK SRLY FLOW...EXPECT LOWEST MINS NEAR THE BAY OF GREEN BAY AS ICE COVER ENHANCES COOLING AND STRENGTHENS NOCTURNAL INVERSION IN THAT AREA. LOWS SHOULD BE AROUND 20F THERE. ON SAT...UNDER STRONG WAA AND ISENTROPIC ASCENT (295K SFC)...EXPECT PCPN TO DEVELOP FROM W TO E AS LOW-LEVEL DRY AIR IS EVENTUALLY OVERCOME. TRAJECTORIES SUGGEST THERE WILL BE SOME MAINTENANCE OF THE LOW-LEVEL DRY AIR OVER THE E EVEN AS FORCING AND RESULTING PCPN ALOFT OVERSPREAD THAT AREA. SO...POPS WILL SHOW A GRADIENT FROM CATEGORICAL W TO JUST CHC E LATE. IT`S QUITE POSSIBLE THE E MAY NOT SEE ANY PCPN SAT. AS FOR PTYPE...IT`S A CHALLENGE AS IT ALMOST ALWAYS IS WHEN IT`S NOT COLD ENOUGH FOR JUST SNOW OR WARM ENOUGH FOR JUST RAIN. THERE WILL BE THE USUAL BATTLE BETWEEN STRONG WAA AND THE COOLING IT GENERATES THRU ASCENT AS WELL AS EVAPORATIVE COOLING EARLY ON. BELIEVE THE EVAPORATIVE COOLING EARLY ON WILL LEAD TO PREDOMINANTLY SNOW AS THE PTYPE INITIALLY. THEREAFTER...FCST SOUNDINGS SHOW PROFILE GENERALLY HOVERING AROUND 0C IN THE LOWER LEVELS...FLUCTUATING BASED ON ASCENT/PCPN INTENSITY. MEANWHILE...THE NEAR SFC LAYER MAY RESPOND A LITTLE TO DAYTIME HEATING...PUSHING THE ODDS TOWARD RAIN. AT THIS POINT...WILL INCLUDE SNOW AS THE GENERAL PREVAILING PTYPE IN MOST AREAS WITH A MENTION OF RAIN. INCLUDED FZRA AS WELL WHERE TEMPS ARE AROUND FREEZING. IF THERE IS FZRA...IT SHOULD BE CONFINED TO THE MORNING/EARLY AFTN BEFORE SURFACES RESPOND TO WEAK DAYTIME HEATING. WITH TEMPS PUSHING INTO THE MID 30S... WET/SLUSHY SNOW ACCUMULATIONS WILL BE MINOR...MAYBE AROUND AN INCH. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 431 PM EST FRI MAR 8 2013 SATURDAY NIGHT... THE MODELS HAVE COME INTO BETTER AGREEMENT WITH THE EVOLUTION OF THE SYOPTIC PATTERN WITH A PROGRESSIVE PATTERN AND LITTLE PHASING BETWEEN THE NRN STREAM MID LEVEL TROUGH MOVING THROUGH NRN ONTARIO AND THE NRN GREATLAKES AND THE SRN STREAM SHORTWAVE MOVING EAST FROM THE PLAINS. ABUNDANT MOISTURE INFLOW WITH MODERATE TO STRONG 285K-300K ISENTROPIC LIFT AND A PERIOD OF 700-600 MB FGEN SHOULD SUPPORT A BAND OF PCPN THROUGH THE CWA...ESPECIALLY BTWN 00Z-06Z WITH QPF AMOUNTS TO AROUND 0.25 INCH. CONFIDENCE IS ALSO HIGHER THAT A SIGNIFCANT (1C TO 3C) WARM LAYER WILL SPREAD THROUGH MOST OF THE CWA GIVEN STRONG WAA WITH SW 40-45 KT 850 MB WINDS BY 00Z/SUN. GENERALLY UTILIZED NAM/GEM LOW LEVEL THERMAL PROFILE TO DELINEATE PCPN TYPE PATTERN. WITH ENOUGH WARMTH LINGERING FROM DAYTIME HEATING...ANY SFC COLD LAYER WILL BE LESS PRONOUNCED LIMITING POTENTIAL FOR FZRA. SO...MAINLY RA/SN MIX EXPECTED WITH THE GREATEST SNOW CHANCES OVER THE WEST HALF. WITH LOW SLR AOB 10/1...ANY WET SNOWFALL AMOUNTS SHOULD ONLY AMOUNT TO AN INCH OR TWO AT MOST. SUNDAY...THERE WERE GREATER MODEL DIFFERENCES AS THE GFS ALLOWS ANOTHER DEFORMATION BAND OF PCPN TO LIFT INTO UPPER ASSOCIATED WITH THE SRN STREAM SHRTWV. SINCE THE GLOBAL GEM/ECMWF CONTINUE TO SHOW A MORE PROGRESSIVE SOLUTION...THE FCST CONTINUES WITH THE IDEA OF TAPERING OFF POPS/QPF FROM WEST TO EAST WITH MAINLY JUST CHANCE POPS BY AFTERNOON. SOME LAKE ENHANCED SNOW MAY DEVELOP BUT WITH THE SYNOPTIC SCALE UPWARD MOTION AND DEEPER MOISTURE DEPARTING...ANY AMOUNTS SHOULD BE LIGHT. SUN NIGHT INTO MON...850 MB TEMPS DROPPING INTO THE -12C TO -14C ALONG WITH CONTINUED CYCLONIC NRLY FLOW COULD STILL SUPPORT SOME LES. HOWEVER...WITH STRONG 850-700 MB DRYING...ANY AMOUNTS ARE EXPECTED TO BE LIGHT TUE-FRI...MDLS WERE CONSISTENT WITH A WEAK CLIPPER SHORTWAVE AND SFC TROUGH MOVING THROUGH THE UPPER GREAT LAKES MON NIGHT INTO TUE. THE FAVORED ECMWF REMAINED MORE AMPLIFIED WITH THE ERN GREAT LAKES TROUGH BY WED WITH COLDER AIR AVAILABLE FOR SOME NW FLOW LES COMPARED TO THE THE GFS. CONFIDENCE IN DETAILS DROPS OFF BY THU-FRI WITH REGARD TO THE POSITION/STRENGTH OF THE NEXT SHORTWAVE THAT COULD BRING SNOW CHANCES INTO THE REGION. TEMPS SHOULD REMAIN AT OR BELOW SEASONAL AVERAGES. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1238 PM EST FRI MAR 8 2013 VFR CONDITIONS SHOULD PREVAIL THRU TONIGHT AT KIWD/KCMX/KSAW GIVEN DRYNESS OF AIR MASS EXPECTED TO BE OVER THE AREA. ONLY EXCEPTION MIGHT BE KSAW AS UPSLOPE FLOW TONIGHT COULD LEAD TO SOME LOW STRATUS DEVELOPING. RIGHT NOW...THAT APPEARS UNLIKELY...BUT IT WILL BE SOMETHING TO MONITOR. APPROACHING LOW PRES TROF SHOULD BRING SOME PCPN/MVFR CONDITIONS TO KIWD/KCMX MID TO LATE MORNING SAT. TEMP PROFILES SUGGEST POTENTIAL FOR A WINTRY MIX...BUT EVAPORATIVE COOLING AS PCPN BEGINS SHOULD LEAD TO PTYPE BEING SNOW. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 431 PM EST FRI MAR 8 2013 SOUTHERLY FLOW WILL DOMINATE TONIGHT THRU SAT EVENING AHEAD OF AN APPROACHING LOW PRES TROF. TYPICAL FOR SOUTHERLY FLOW...STRONGEST WINDS WILL BE OVER ERN LAKE SUPERIOR...REACHING UPWARDS OF 30KT SAT AFTN/EVENING. TROF WILL THEN PASS ACROSS LAKE SUPERIOR LATE SAT NIGHT/SUN...BRINGING A SHIFT TO 20-30KT NW WINDS. WINDS WILL THEN SLOWLY SUBSIDE LATE SUN NIGHT/MON...FALLING TO UNDER 15KT FOR MON NIGHT/TUE. MAY SEE A SLIGHT INCREASE IN WINDS WED. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...ROLFSON LONG TERM...JLB AVIATION...ROLFSON MARINE...JLB
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1155 AM CST FRI MAR 8 2013 .DISCUSSION...LATEST RADAR IMAGERY...BOWMAN AND BISMARCK RADARS CONTINUE TO REFLECTIVITY`S ENHANCING IN THE SOUTHWEST. WILL CONTINUE WITH THE LIKELY POPS THIS AFTERNOON...MOVING UP ALONG THE WESTERN BORDER TOWARD 00Z SATURDAY...PER LATEST RAP AND GFS. COULD BE A MIX OF SLEET AND SNOW AS WELL WITH SOUNDINGS ADVERTISING A MODEST WARM POCKET WITH TEMPS AROUND +1 TO +2C IN A SHALLOW LAYER. CONCERN FOR TONIGHT AND SATURDAY IS POSSIBLE WINTER WEATHER ADVISORY IN THE FAR SOUTHEAST COUNTIES. 12Z MODELS REMAIN ERRATIC ON MAX/MIN QPF POSSIBILITIES. CONSIDERING GOING THE MIDDLE OF THE ROAD WHICH MEANS A 2 TO 4 INCH POSSIBILITY IN THE FAR SOUTHEAST. WILL CONTINUE TO LOOK AT THINGS AND HAVE A DECISION MADE LATER THIS AFTERNOON. REST OF FORECAST REMAINS ON TRACK. && .AVIATION...AT NOON CST...COLD FRONT EXTENDED FROM A LOW AT MANITOBA/ONTARIO BORDER TO NEAR PEMBINA TO NEAR KJMS. NORTHWEST WINDS AT KMOT/KJMS EARLY THIS AFTERNOON. MEANWHILE THE SOUTHERN STORM SYSTEM WITH A LOW OVER COLORADO/WYOMING WILL KEEP ELY/NELY WINDS AT KISN/KDIK/KBIS...AND BRING ELY/NELY WINDS TO KMOT/KJMS BY 21Z-00Z THIS AFTERNOON. LARGE MID-LEVEL CLOUD SHIELD MOVING NORTHWARD FROM THE SOUTH WILL ENCOMPASS TAF SITES. AT THE SAME TIME...EXPECT MVFR CIGS TO DEVELOP AT ALL TAF SITES BEGINNING AT KDIK WITH EASTERLY UPSLOPE FLOW AND SPREADING NORTH AND EAST AFT 00Z. LIGHT SNOW WITH POSSIBILITY MIX WITH SLEET AT KDIK THIS AFTERNOON...THEN CHANCES OF LIGHT SNOW TONIGHT AT MOST TAF SITES. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ DISCUSSION...KS AVIATION...JV
AREA FORECAST DISCUSSION
NWS CHARLESTON WV
1241 PM EST FRI MAR 8 2013 .SYNOPSIS... LOW PRESSURE OFF THE EAST COAST DRIFTS SLOWLY AWAY TODAY...ALLOWING HIGH PRESSURE TO BUILD IN THIS WEEKEND. A COLD FRONT AND WAVE OF LOW PRESSURE MOVE THROUGH MONDAY INTO TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... INCREASED THE CLOUD COVER PER LOCAL MODEL AND RUC 900-850MB MOISTURE ADVECTION FROM THE NORTH. NAM NOT PICKING UP ON THIS AS WELL. PREVIOUS DISCUSSION FOLLOWS... OVERALL RELATIVELY QUIET WEATHER IN THE NEAR TERM PERIOD. DOUBLE BARREL LOW PRESSURE CONTINUES TO REMAIN ALONG THE EAST COAST OF THE U.S...PLACING THE CWA IN A NW FLOW PATTERN...WITH LIGHT SNOW SHOWER/FLURRY ACTIVITY CONTINUING ACROSS NORTHERN ZONES. MUCH OF THIS ACTIVITY WILL TAPER OFF BY LATE MORNING OR EARLY AFTERNOON...AS RIDGE OF HIGH PRESSURE FROM THE WEST BUILDS IN...PUSHING THE LOW FARTHER TO THE EAST. THIS COMBINED WITH SURFACE HIGH PRESSURE BUILDING IN FROM THE NORTH...WILL GRADUALLY RESULT IN LESS FAVORABLE FLOW FOR CONTINUED SNOW SHOWER ACTIVITY. DRIED OUT POPS ACROSS THE CWA SEVERAL HOURS EARLIER THAN THE PREVIOUS FORECAST. LOW LEVEL MOISTURE TRAPPED BENEATH INVERSION IS GRADUALLY STARTING TO ERODE...AND EXPECT IT TO CONTINUE THROUGHOUT THE DAY...WITH NORTHERN/MOUNTAIN ZONES SLOWER TO CLEAR. WITH THE CLEARING SKY...AND BUILDING HIGH...EXPECT A NIGHT OF GOOD RADIATIONAL COOLING...AND ELECTED TO GO ON THE COLDER SIDE OF GUIDANCE...BUT KEPT RIDGE TOPS WARMER THAN MOUNTAIN VALLEYS DUE TO BUILDING RIDGE. MAY EVEN SEE SOME PATCHY FOG IN MOUNTAIN VALLEYS SATURDAY MORNING...BUT NOTHING WIDESPREAD. ELECTED TO BUMP MAX TEMPS FOR TODAY DOWN SLIGHTLY FROM PREVIOUS FORECAST AS AREA REMAINS IN NORTHERLY FLOW. && .SHORT TERM /SATURDAY THROUGH MONDAY/... NEED A SPRING FEVER ALERT IN THE HWO FOR THE WEEKEND. NAM12 APPEARS FAST WITH PASSAGE OF FRONT SUN NT. WENT WITH OTHER GLOBAL MODELS...WHICH HOLD THE FRONT...AND ITS ASSOCIATED PRECIPITATION...UP FOR A TIME SUN NT...ON ACCOUNT OF A SOUTHERN STREAM WAVE. THE FRONT THEN STARTS MOVING E AGAIN LATER SUN NT AND MON...AS THE WAVE GOES BY...THERE ARE GLOBAL MODEL INCONSISTENCIES IN THE TIMING OF THIS WAVE. GFS INSTABILITY PARAMETERS DO NOT REALLY SUPPORT THUNDER S OF THE WAVE AND AHEAD OF THE COLD FRONT MON AFTERNOON. HOWEVER...LEFT THE SLIGHT CHANCE ALREADY IN THE GRIDS ALONE FOR NOW PENDING POSSIBLE CHANGES IN FCST PARAMETERS. NO MAJOR CHANGES IN TEMPERATURES WHICH JIBED WELL IN LIGHT OF LATEST GUIDANCE. LOWERED DEW POINTS AND LOWS A LITTLE OVER THE WEEKEND WHILE HIGHS ARE AT OR ABOVE PREVIOUS SAT AND UNCHANGED SUN...MID 60S IN CHARLESTON. COOLING FROM THE W MON WILL BE A FUNCTION OF TIMING OF THE FRONT AND ITS ASSOCIATED PRECIPITATION...SOME OF WHICH MAY BE BEHIND THE FRONT DEPENDING UPON THE TIMING OF THE WAVE. HIGH TERRAIN WILL BE COOLER W/R FCST H85 TEMPERATURES THAN USUAL UNTIL THE FOOT-PLUS SNOW PACK UP THERE IS ABOUT GONE. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... MOISTURE FROM THE LEADING EDGE OF THE NEXT FRONTAL SYSTEM WILL BEGIN TO SPREAD OVER THE WESTERN PORTIONS OF THE FORECAST AREA LATE SUNDAY NIGHT AS THE WEEKENDS UPPER LEVEL RIDGE SLIDES EAST INTO THE ATLANTIC. RAINFALL WILL BECOME MORE WIDESPREAD THROUGH THE DAY MONDAY AS A FRONTAL SYSTEM WITH A GOOD SOUTHERLY FETCH SHIFTS EAST. WITH TEMPERATURES REMAINING WARM DURING THIS TIME PERIOD WILL NEED TO WATCH THE FRONT CLOSELY FOR HYDRO CONCERNS. SO FAR MODELS ARE SHIFTING IT EAST QUICKLY ENOUGH TO KEEP PRECIPITATION AMOUNTS IN THE INCH RANGE BUT IF WAVES END UP FORMING ALONG THE FRONTAL BOUNDARY AND IT STALLS...THE NORTH TO SOUTH ORIENTATION OF THE SYSTEM WOULD BE FAVORABLE FOR PICKING A GOOD BIT MORE RAIN. AGAIN AT MOMENT IT DOES NOT LOOK LIKE THE FRONT WILL STALL BUT RATHER JUST SOMETHING TO WATCH. COOLER AIR WILL SWING DOWN BEHIND THE FRONTAL MIDWEEK BUT LOOKS FAR ENOUGH BEHIND THAT MOST OF THE LINGERING POST FRONTAL SHOWERS WILL BE OVER WITH BY THEN. && .AVIATION /17Z FRIDAY THROUGH TUESDAY/... LOW LEVEL MOISTURE CONTINUES TO ADVECT FROM THE NORTH...AND WILL KEEP THE TERMINALS ON THE CUSP OF MVFR CONDITIONS. EXPECT CLEARING THIS EVENING AND EARLY TONIGHT...AND COULD SEE SOME MVFR MIST DEVELOPING OVER THE NORTHEAST MOUNTAIN VALLEYS LATE TONIGHT. FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 18Z SATURDAY... FORECAST CONFIDENCE...HIGH. ALTERNATE SCENARIOS: UNCERTAINTY IN DEVELOPMENT OF MVFR MIST TONIGHT. EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY OF WFO FORECAST TO AVAILABLE MODEL INFORMATION: H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS. L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL. UTC 1HRLY 18 19 20 21 22 23 00 01 02 03 04 05 EST 1HRLY 13 14 15 16 17 18 19 20 21 22 23 00 CRW CONSISTENCY M M M M M M M M M M M M HTS CONSISTENCY M M M M M M M M H H M H BKW CONSISTENCY H M M H M H H H H H H H EKN CONSISTENCY H H H H H H H H M M M M PKB CONSISTENCY M M M M M M M M M M M M CKB CONSISTENCY H H H M M M M M M M M M AFTER 18Z SATURDAY... IFR POSSIBLE IN RAIN SHOWERS MONDAY INTO MONDAY NIGHT. && .RLX WATCHES/WARNINGS/ADVISORIES... WV...NONE. OH...NONE. KY...NONE. VA...NONE. && $$ SYNOPSIS...TRM/SL NEAR TERM...SL/26 SHORT TERM...TRM LONG TERM...JR AVIATION...26
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1035 AM MST FRI MAR 8 2013 .UPDATE... ISSUED AT 853 AM MST FRI MAR 8 2013 15Z SURFACE ANALYSIS HAD A WEAK COLD FRONT ACROSS MT INTO SOUTHERN ND. WATER VAPOUR HAD LARGE UPPER TROUGH WITH UPPER LOW DIGGING INTO SOUTHERN CA. SOUTHWEST FLOW ALOFT AHEAD OF SYSTEM PRODUCING STREAM OF MID/HIGH CLOUDS OVER THE CWA. EMBEDDED SHORTWAVE OVER SOUTHEAST MT...UNDER RIGHT ENTRANCE REGION OF 90KT JET...PRODUCING SOME WEAK RADAR RETURNS OVER NORTHWEST SD. AREA ALSO IN A REGION OF WEAK LOW LEVEL FRONTOGENESIS...WHICH SHOULD PERSIST MOST OF THE DAY PER 12Z RAP AND THUS WILL CONTINUE LOW POPS IN FAR NORTHWEST PORTIONS OF CWA. PRESSURE FALLS OVER EASTERN WY/MT SUPPORTING EAST/SOUTHEAST LOW LEVEL FLOW AND SOME FOG OVER PORTIONS OF CENTRAL SD. FOG SHOULD MIX AWAY SOME BY EARLY AFTERNOON...SO HAVE EXPANDED AND EXTENDED CURRENT AREA OF FOG TO COVER SOUTHEAST THIRD OF THE CWA. FINALLY...12Z NAM CONTINUES TREND OF FASTER NORTHERN STREAM TROUGH...WHICH WILL PUSH CA TROUGH FURTHER SOUTH AND EAST OF CWA. HAVE ADJUSTED POPS TO MATCH SLOWER ONSET OF PRECIPITATION THIS EVENING. && .SHORT TERM...(TODAY THROUGH SATURDAY NIGHT) ISSUED AT 351 AM MST FRI MAR 8 2013 DIGGING SW CONUS UPPER TROUGH WILL EJECT TOWARD THE REGION IN THE PERIOD AND SUPPORT CYCLOGENESIS OVER THE CENTRAL PLAINS. MEANWHILE A FAST MOVING NORTHERN STREAM TROUGH WILL DROP INTO THE NORTHERN PLAINS JUST AHEAD OF THE SW CONUS TROUGH...EVENTUALLY PHASING EAST OF THE REGION. FORECAST MODELS HAVE STRUGGLED WITH FORECAST DETAILS FOR THE LAST SEVERAL RUNS...KEEPING THE TRACK WELL SOUTH OF THE FA AT FIRST/THEN SHIFTING THE TRACK NW FOR SEVERAL CYCLES /WITH THE LATEST SUITE SUPPORTING A SHIFT BACK TO THE SOUTH. THE EXACT TRACK WILL HINGE UPON TWO MAIN FEATURES: 1/ HOW FAST THE NORTHERN STREAM TROUGH PROPAGATES INTO THE NORTHERN PLAINS AHEAD OF THE EJECTING SW CONUS UPPER TROUGH. 2/ THE INTENSITY OF THE FORWARD FLANK JET STREAK WHICH WILL DETERMINE THE DEGREE OF POSITIVE TROUGH TILT AND ASSOCIATED SHEARING OF THE THE SW CONUS UPPER WAVE...HIGHLY AFFECTING THE SPEED AND LIFT PLACEMENT. CURRENT TRENDS SUPPORT A STRONGER POSITIVE TILT TO THE SW CONUS UPPER WAVE...WITH A ASSOCIATED FASTER PROPAGATION SPEED...BRINGING IN A VERSION OF STRONGER SUBSIDENCE...WITH ASSOCIATED LL DRYING OVER MUCH OF THE WESTERN 2/3 OF THE FA SAT. IN ADDITION..LL THERMAL FIELDS HAVE TRENDED SLIGHTLY WARMER IN THE LATEST CONSENSUS BLEND...WITH MANY LOCATIONS EXPECTED TO BE WELL IN THE 30S AND EVEN LOWER 40S ON SAT...SAVE FAR SOUTH CENTRAL WHERE THE STRONGER COLLOCATION OF DEEP LAYER LIFT WILL BE PRESENT. THE POTENTIAL FOR MIXED PRECIP WITH A PERIOD OF FREEZING RAIN EXISTS OVER SCENTRAL LATE TONIGHT INTO SAT MORNING...ALTHOUGH AS STATED EARLIER...FORECAST MODELS HAVE TERNED WARMER PER THERMAL FIELDS...WITH LOCATIONS INVOF ICR REMAINING ABOVE FREEZING UNTIL SAT MORNING. ACCUMULATING SNOWFALL LOOKS TO REMAIN CONFINED TO THE FAR SOUTH AND SCENTRAL FA...WITH STRONG INDICATIONS REMAIN FOR POTENTIAL DEFORMATION BANDING OVER FAR SCENTRAL SAT AFTERNOON...A SOLUTION INDICATED IN NAM/GFS/SREF/AND ECMWF SOLUTIONS. QUESTION REMAINS THROUGH WHERE AND THIS BAND WILL SETUP AND THE DEGREE OF LL MOISTURE IN PLACE WHEN THE STRONGEST ROUND OF DEEP ASCENT DEVELOPS IN THAT LOCATION. LINGERING WEAK WAA/DEFORMATION ZONE WILL CONTINUE TO SHIFT NORTH OUT OF THE FA THIS MORNING...WITH ONLY SMALL CHANCES FOR PRECIP GIVEN WEAK FORCING AND DRY LL/S. OTHERWISE...THE NEXT ROUND OF STRONG WAA WILL ENSUE THIS EVENING OVER SOUTHERN PORTIONS OF THE FA...SPREADING NORTH OVERNIGHT. IT IS ENTIRELY POSSIBLE THAT THE MAJORITY OF PRECIP MAY BE CONFINED TO THE FAR SE PORTION OF THE FA...WITH MUCH UNCERTAINTY REMAINING PER THE DETAILS OF THE THIS FIRST ROUND OF WAA. RETAINED A MIXED POTENTIAL FOR THIS IN SE...WITH GENERAL RAIN CHANGING TO SNOW CHANCES ELSEWHERE. NORTHERN STREAM TROUGH WILL DIVE IN THE NORTHERN PLAINS AND SUPPORT A ROUND OF LARGE SCALE SINK OVER MUCH OF THE FA SAT...SUPPORTING LL DRYING OVER MUCH OF THE FA. DID TREND POPS DOWN AND TO THE SOUTH GIVEN THIS CONCERN. OTHERWISE...INCREASING LARGE SCALE ASCENT INDICATED IN Q-VECTOR PROGS IS EXPECTED OVER THE SOUTHERN PORTIONS OF THE FA...MAINLY SOUTH AND EAST OF A PINE RIDGE TO KADOKA LINE LATE SAT MORNING. ASSOCIATED LIFT MAY CONTINUE TO SUPPORT MIXED PRECIP. HOWEVER...DEEP AND STRONG ASCENT WILL LIKELY SUPPORT ENOUGH DYNAMIC COOLING TO SUPPORT ALL SNOW OVER SCENTRAL AREAS BY MID MORNING. OTHERWISE...THE REMAINDER THE FA MAY NOT SEE MUCH IN THE WAY OF PRECIP GIVEN STRONG SINK AND DRYING LL/S. THIS INCLUDES THE NORTHERN HILLS WHERE MOISTURE LOOKS TO BE LIMITED. THE NAM CERTAINLY DISPLAYS A SHARP CUT OFF TO PRECIP IN QPF PROGS WHICH LOOKS HIGHLY CREDIBLE. A RATHER WARM BL MAY LIMIT ACCUMS OVER PORTIONS OF THE SOUTHERN FA...HOWEVER THE POTENTIAL FOR UP TO 4 INCHES REMAIN OVER THE FAR SE...MELLETTE/TODD/TRIPP COUNTIES...WITH A LIKELY HEAVY WET LOWER RATIO SNOW BEING FAVORED. TRIED TO INCORPORATED A SHIFT OF THE HIGHEST POPS SE...LOWERING THE NW. WILL CONTINUE THE SPS AS DETAILS ARE STILL LACKING AND WARNING CRITERIA NOT EXPECTED. STRONG GUSTY NW WINDS ARE ALSO EXPECTED SAT AFTERNOON...ESP ON THE EASTERN BH FOOTHILLS. HOWEVER...WARM BL TEMPS ABOVE FREEZING MAY HIGHLY LIMIT BLOWING SNOW POTENTIAL. UPPER TROUGH AND ASSOCIATED LIFT WILL QUICKLY SHIFT EAST AND WANE OVER THE FA SAT EVENING...WITH ALL PLACES DRY AFTER MIDNIGHT. .LONG TERM...(SUNDAY THROUGH THURSDAY) ISSUED AT 351 AM MST FRI MAR 8 2013 TEMPERATURES WILL GRADUALLY WARM INTO EARLY NEXT WEEK AS RIDGE BUILDS OVER THE WESTERN CONUS. A VARIETY OF WEAK DISTURBANCES MOVING THROUGH WILL BRING LOW PRECIP CHANCES TO PTNS OF THE AREA THROUGH THE FIRST PART OF THE WEEK. RIDGE CONTINUES TO AMPLIFY OVER THE AREA FOR THE LAST PART OF THE WORK WEEK BRINGING DRY CONDITIONS AND WARM TEMPS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1035 AM MST FRI MAR 8 2013 ISOLD RAIN OR SNOW SHOWERS MAY LINGER OVER NORTHEAST WYOMING INTO NORTHWEST SOUTH DAKOTA TODAY BRINGING LCL MVFR CIGS/VIS. FOR TONIGHT...RAIN AND SNOW WILL DEVELOP OVER THE AREA...THEN TRANSITIONING TO ALL SNOW. THE GREATEST CHANCES WILL BE OVER SOUTH CENTRAL SOUTH DAKOTA WHERE SOME FREEZING RAIN MAY ALSO DEVELOP. WIDESPREAD IFR CIGS WITH AREAS OF IFR VSBY ARE EXPECTED OVER MUCH OF THE AREA THROUGH THE FORECAST PERIOD. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...JC LONG TERM...77 AVIATION...13
AREA FORECAST DISCUSSION
NWS FORT WORTH TX
1014 AM CST FRI MAR 8 2013 .UPDATE... LEAD SHORTWAVE IS PRODUCING ISENTROPIC LIFT IN THE MID AND HIGH LEVELS ACROSS NORTH TEXAS. A LAYER OF DRY AIR BETWEEN 600-800MB IS CAUSING MOST OF THE PRECIPITATION TO EVAPORATE BEFORE REACHING THE GROUND. SOME GRADUAL SATURATION WILL OCCUR THROUGH THE DAY ALLOWING FOR SOME LIGHT RAIN OR SPRINKLES TO REACH THE GROUND. HOWEVER ANY RAIN AMOUNTS WILL BE FAIRLY LIGHT. WILL DROP POPS TO 20 PERCENT FOR THE ENTIRE AREA TODAY AND TONIGHT. OTHERWISE HAVE MADE SOME MINOR ADJUSTMENTS TO TODAYS HIGHS...MAINLY TO LOWER THEM DUE TO THE PERSISTENT CLOUDY CONDITIONS. TR.92 && .AVIATION... CHALLENGES FOR THE 12Z TAF SET INCLUDE CIG TRENDS BETWEEN MVFR AND LOW VFR AND TIMING OF RAIN CHANCES WITH A LEAD DISTURBANCE THIS AFTERNOON. STRATO-CU IN THE MVFR/VERY LOW VFR RANGE HAS BEEN SURGING NORTH ACROSS THE TERMINALS IN ADVANCE OF A LEAD SHORTWAVE DISTURBANCE ROTATING NORTHEAST OUT OF OLD MEXICO AND THE RIO GRANDE VALLEY. THOUGH THERE MAY BE A BRIEF WINDOW FOR LOW VFR CIGS BETWEEN 030-040 THIS MORNING...WILL LEAN WITH MODEL BUFR AND RUC OPS40 SOUNDINGS WITH GOING WITH A PREVAILING MVFR AROUND 025...BUT WITH A TEMPO GROUP FOR LOW MVFR CIGS BETWEEN 015-020 THROUGH LATE MORNING. ISENTROPIC ASCENT THIS AFTERNOON SHOULD HELP TOP-DOWN COLUMN SATURATION OCCUR QUICKLY AND SOME -RA/-SHRA OCCURRING BETWEEN 21Z AND 01Z. HAVE INTRODUCED A PROB30 GROUP TO COVER THIS VERY LIGHT RAINFALL THAT IS EXPECTED THIS AFTERNOON. THE LEAD SHORTWAVE EXITS TO THE NORTHEAST EARLY THIS EVENING WITH A BRIEF WINDOW FOR CIGS IMPROVING TO LOW VFR ONCE AGAIN...BEFORE RETURNING TO THE MVFR CATEGORY BY MIDNIGHT AND BEYOND. SOUTHEAST WINDS 10-15 KTS WILL CONTINUE THROUGHOUT THE FORECAST. OUTLOOK... MODELS HAVE SPED UP TIMING OF DRYLINE/FRONT IN ADVANCE OF OUR MAIN SYSTEM ROTATING SOUTHEAST CURRENTLY OVER SRN CA/WRN AZ. IT APPEARS THE MAIN WINDOW FOR +TSRA WILL BE 21Z-03Z SATURDAY WITH WINDS SHIFTING NORTHWEST AND VERY GUSTY BEHIND THE COLD FRONT BY 12Z SUNDAY. 05/ && .PREV DISCUSSION... /ISSUED 313 AM CST FRI MAR 8 2013/ 0UR NEXT UPPER STORM SYSTEM WILL BE MOVING INTO SOUTHERN CALIFORNIA THIS MORNING WITH CYCLOGENESIS UNDERWAY ALONG THE FRONT RANGE OF COLORADO. THE UPPER LOW WILL MOVE REACH THE 4-CORNERS SATURDAY MORNING AND KANSAS BY SATURDAY EVENING. A TROUGH EXTENSION WILL HANG BACK INTO SOUTHERN ARIZONA AS THE MAIN UPPER LOW CONTINUES INTO THE MIDWEST. SATURDAY THROUGH SATURDAY NIGHT...THE 300MB JET WILL BE INCREASING FROM LESS THAN 60 KNOTS IN THE MORNING TO 90-100KTS IN THE EVENING WHICH WILL HELP TO INCREASE 0-6KM BULK SHEAR INTO THE 60-70 KNOTS RANGE. BEST CAPE VALUES...300-600 J/KG...WILL OCCUR OVER THE SOUTHWEST AND WESTERN COUNTIES SATURDAY AFTERNOON WHICH SHOULD BE WHERE THE STRONGEST...POSSIBLY SEVERE... STORMS OCCUR WITH THIS SYSTEM LATE SATURDAY AFTERNOON. ALTHOUGH SHEAR REMAINS HIGH SATURDAY EVENING AND OVERNIGHT...WEAKENING INSTABILITY AND MID LEVEL LAPSE RATES SHOULD RESULT IN A DIMINISHED CHANCE OF SEVERE STORMS BY MID EVENING SATURDAY. AS THE PACIFIC PUSHES THROUGH THE CWA SATURDAY NIGHT...THE LINE OF STORMS COULD PRODUCE RAINFALL OF 1/2 TO 1 INCH WITH THE SOUTHEAST THIRD HAVING THE BEST CHANCE TO SEE 3/4 TO OVER 1 INCH BEFORE ENDING. ON SUNDAY...THE REMAINING UPPER TROUGH TO OUR WEST WILL SLIDE ACROSS THE REGION...AND MAY PRODUCE SOME LIGHT RAIN FROM LINGERING MID LEVEL MOISTURE...BUT AMOUNTS WILL BE LIGHT. COLDER AIR ARRIVES BEHIND THE FRONT FOR THE FIRST OF THE WORK WEEK. THE WESTERN AND NORTHERN AREAS MAY SEE A FREEZE ON TUESDAY MORNING. THE REST OF NEXT WEEK WILL BE DRY WITH TEMPERATURES MODERATING TO ABOVE NORMAL. 75 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 65 57 69 50 58 / 20 20 40 80 20 WACO, TX 67 58 72 51 58 / 20 20 30 70 60 PARIS, TX 63 53 66 52 58 / 20 20 20 70 40 DENTON, TX 65 58 69 48 57 / 20 20 50 80 20 MCKINNEY, TX 64 56 67 49 58 / 20 20 30 80 30 DALLAS, TX 65 57 68 52 58 / 20 20 40 80 30 TERRELL, TX 65 55 68 53 58 / 20 20 20 70 40 CORSICANA, TX 67 57 69 55 59 / 20 20 20 70 60 TEMPLE, TX 67 59 72 53 59 / 20 20 30 70 70 MINERAL WELLS, TX 66 59 72 47 57 / 20 20 50 60 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$