Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 042050 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 350 PM EST WED MAR 4 2015 .SYNOPSIS...
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A COLD FRONT SLOWLY CROSSES THE REGION EARLY THIS EVENING THROUGH TONIGHT. THE FRONT WILL STALL OVER NORTH CAROLINA ON THURSDAY...WITH A WAVE OF LOW PRESSURE MOVING ALONG THE FRONT THURSDAY AFTERNOON AND NIGHT. THIS WILL BRING ANOTHER ROUND OF WINTRY WEATHER TO THE AREA...FOLLOWED BY COLD AND DRY CONDITIONS BY FRIDAY. GRADUALLY MODERATING...MILDER TEMPERATURES ARE EXPECTED LATE IN THE WEEKEND INTO NEXT WEEK.
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&& .NEAR TERM /THROUGH THURSDAY NIGHT/...
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LATEST WX ANALYSIS FEATURES A WELL DEFINED FRONTAL BOUNDARY OVER THE MID SOUTH/LWR OHIO VALLEY THAT SEEMS TO HAVE PHASED WITH ANOTHER, MORE DIFFUSE BOUNDARY STRETCHING FROM THE WV PANHANDLE INTO THE INTERIOR NORTHEAST. WEAK FORCING HAS GENERALLY KEPT PRECIP AT BAY THIS AFTERNOON. WHERE CAD WEDGE WAS ABLE TO BE FULLY ERODED ACROSS THE SOUTHERN CWA, TEMPS HAVE CLIMBED NICELY AS EXPECTED INTO THE U60S/L70S. POPS REMAIN 30-40% FOR SOME SPOTTY SHRAS ACROSS THE NORTH THROUGH EARLY EVENING, THOUGH WILL DEPICT GRADUAL RAMP UP OF POPS IN THE GRIDS THIS EVENING AND OVERNIGHT ACROSS THE NORTH AS FRONT TO THE NORTHWEST DROPS ACROSS THE AREA SLOWLY THROUGH LATE TONIGHT. MODELS REMAIN IN GOOD AGREEMENT WITH RESPECT TO FRONTAL TIMING, AND HAVE USED A GFS/NAM BLENDED SOLUTION FOR TIMING IN THE NEAR TERM. STILL EXPECTING INITIAL WAVE OF LOW PRESSURE TO MOVE SW TO NE ALONG THE FRONT AND TRACKS ACROSS THE CAROLINAS LATE TONIGHT INTO THURSDAY. MUCH COLDER AIR ARRIVES BEHIND THE FRONT WITH MOST OF THE AREA FALLING INTO THE UPPER 20S/LOW 30S BY THU AFTN. BUFR FORECAST SOUNDINGS CONTINUE TO DEPICT DRY AIR LINGERING BETWEEN 600-400MB TONIGHT...SO ANY PCPN (IN THE FORM OF -RA) OVERNIGHT WILL BE LIGHT. A STRONG ANTI-CYCLONIC JET IN PLACE FROM THE MID MISS VLY THROUGH ATLANTIC CANADA WILL TRANSLATE EWD THROUGH THE DAY THU AS A STRONG TROUGH DIGS ACROSS THE UPPER MIDWEST AND GREAT LAKES BY LATER THU MORNING INTO THU AFTERNOON. IT IS AT THIS TIME THAT DEEPER MOISTURE WILL ARRIVE AND RRQ FORCING WILL BE IDEALIZED, AS STRONG PV ANOMALY RIDES ACROSS THE AREA THU THROUGH THU NIGHT, TRIGGERING THE ONSET OF WINTRY PCPN FROM NW-SE ACROSS THE AREA. CRITICAL H85-7 THICKNESS VALUES (SUB 1540M) ARE NOT REALIZED UNTIL LATE IN THE AFTN THU INTO THU NIGHT OVER NORTHERN HALF OF THE AREA. HOWEVER...BY THIS TIME THE STRONGEST UVM WILL BE EXITING THE COAST. OVERALL, UTILIZING ROEBBER SLR FORECASTING TOOL ALONG WITH LOCAL THICKNESS CHART, FORECAST SLR VALUES WILL BE QUITE LOW FOR MUCH OF THE DAY (PERHAPS AS LOW AS 4:1-8:1). THIS MAKES SENSE GIVEN THAT THERE WILL BE A PROLONGED PERIOD OF SLEET (WHICH WILL EAT INTO SNOWFALL TOTALS)...AND THAT MID-LEVEL THICKNESSES WILL BE `WARM` DURING THE STRONGEST FORCING IN THE EARLY TO MID AFTERNOON HOURS. BASED ON ALL OF THE ABOVE, HAVE CONTINUED WITH A STRIPE OF 3-5" OF WET SNOW/SLEET ALONG A LINE FROM PALMYRA, VA TO TAPPAHANNOCK AND SALISBURY, MD. THIS IS BORDERED BY A BAND OF 2-3" FOR OTHER PORTIONS OF THE NW PIEDMONT...NRN NECK...NORTHERN RIC SUBURBS AND REMAINDER OF THE LOWER MD EASTERN SHORE. CURRENTLY 1-2" OF SLEET/SNOW IS FORECAST FROM THE SOUTHERN SECTIONS OF THE RIC METRO /TRI-CITIES DOWN THROUGH HAMPTON ROADS...WITH 1" OR LESS ALONG THE HIGHWAY 58 CORRIDOR OVER CENTRAL VA INTO THE PIEDMONT. THIS TRANSLATES TO WINTER STORM WARNINGS BEING HOISTED ALONG OUR NORTHERN TIER OF COUNTIES, WITH A TIER OF WINTER WEATHER ADVISORIES FOR THE RIC METRO AREA, THE PIEDMONT AND THE MIDDLE PENINSULA MAINLY ALONG AND NORTH OF A FARMVILLE TO PETERSBURG AND WILLIAMSBURG LINE. CONFIDENCE IS NOT HIGH ENOUGH TO CONTINUE ADVISORIES FARTHER SOUTH INTO SOUTH CENTRAL VA COUNTIES. GIVEN THAT ANY IMPACTS WOULD COME THURSDAY NIGHT IN THIS AREA, HAVE THEREFORE CONTINUED HWO MENTION GIVEN EXPECTATION OF SUB-ADVISORY CONDITIONS. WINTRY PCPN SHOULD TAPER OFF THU EVENING...AS TOP DOWN DRYING ENSUES W/DRIER AIR ARRIVING FROM THE NW DURING THE LATE EVENING. COULD SEE A BRIEF PERIOD OF FREEZING DRIZZLE LATE THU EVENING, HENCE DRAGGING ALL WINTER HEADLINES THROUGH MIDNIGHT THU NGT/FRI MORNING.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY/...
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HIGH PRESSURE/FAIR WEATHER TO PREVAIL DURING THE SHORT TERM. SHORTWAVE EXITS THE NE COAST FRI MORNING WITH CONFLUENCE ALOFT OVER THE MID-ATLANTIC. THIS WILL ALLOW STRONG 1030+MB ARCTIC HIGH PRESSURE TO CENTER OVER THE REGION FRI. COLD FRONT LOCATES OFFSHORE...EXTENDING SWWD INTO THE NRN GULF. BEST MOISTURE GETS SHUNTED OFFSHORE IN INCREASING WLY FLOW ALOFT. THE RESULT WILL BE DRY CONDITIONS...BUT WELL BELOW NORMAL TEMPERATURES. H85 TEMPS ~-8C AND LOW LEVEL THICKNESSES YIELD TEMPS IN THE LOW-MID 30S...POSSIBLY UPPER INTERIOR MD ERN SHORE. THE NEXT NRN STREAM SHORTWAVE CROSSES THE REGION FRI NIGHT...RESULTING IN LITTLE MORE THAN PARTLY CLOUDY SKIES. COLD FRI NIGHT WITH LOW GENERALLY MID TEENS TO AROUND 20. ZONAL FLOW DEVELOPS SUN AS HIGH PRESSURE REMAINS OVER THE REGION. SWLY RETURN FLOW COMMENCES...RESULTING IN MODERATING LOW LEVEL THICKNESSES AND TEMPS. THICKNESSES YIELD TEMPS IN THE LOW-MID 50S INLAND SUN...BUT GUIDANCE RUNNING IN THE MID-UPPER 40S. TRENDED TOWARD THICKNESSES...WITH HIGHS IN THE UPPER 40S-LOW 50S INLAND AND LOW TO MID 40S NEAR THE COAST...UNDER MOSTLY SUNNY TO PARTLY CLOUDY SKIES.
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&& .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... EXTENDED PERIOD WILL BE HIGHLIGHTED BY GENERALLY DRY CONDITIONS AND A RETURN TO NEAR SEASONABLE NORMAL TEMPS. MEDIUM RANGE GUIDANCE IN GENERAL CONSENSUS WITH THE UPPER FLOW THRU THE EXTENDED...CHARACTERIZED BY RIDGING/BLOCKING OVER THE WRN CONUS/ERN PACIFIC AND BROAD TROUGHING OVER THE CNTRL AND ERN CONUS. TO BEGIN THE PERIOD...COLD/DRY 1030+MB ARCTIC HIGH PRESSURE CENTERS OVER THE MID-ATLANTIC REGION. THURSDAYS COLD FRONT LOCATES OFF THE COAST...EXTENDING SWWD INTO THE NRN GULF. H85 TEMPS DROP TO AROUND -8C FRI (~-1 STD DEV)...SLIGHTLY WARMER THAN DEPICTED 24 HRS AGO. HIGHS FRI GENERALLY IN THE LOW-MID 30S INLAND AND UPPER 20S-LOW 30S COASTAL AREAS. AIRMASS MODIFIES FRI NIGHT-SAT AS THE COLD/DRY AIR RETREATS NWD. HIGH PRESSURE REMAINS OVER THE REGION SAT...WITH LIGHT RETURN FLOW HELPING TO MODERATE LOW LEVEL THICKNESSES. TEMPS WARM INTO THE UPPER 40S-LOW 50S INLAND AND LOW- MID 40S COASTAL AREAS. SKY AVG MOSTLY SUNNY-PARTLY CLOUDY. HIGH PRESSURE REMAINS OVER THE REGION SUN...RESULTING IN CONTINUED DRY AND WARMING CONDITIONS. HIGHS IN THE LOW-MID 50S INLAND AND LOW 40S TO UPPER 40S COASTAL AREAS. ATTENTION THEN TURNS OUT WEST...WHERE MODELS CONTINUE TO STRUGGLE HANDLING SPLIT/BLOCKY FLOW AND SRN STREAM ENERGY OVER THE DESERT SW/BAJA. GOOD NEWS IS THAT NOW THE DETERMINISTIC ECMWF HAS TRENDED DRY SUN NIGHT-EARLY NEXT WEEK...MATCHING THE GFS AND ENSEMBLES. HOWEVER...SPLIT FLOW CONTINUES RESULTING IN LOW CONFIDENCE EARLY NEXT WEEK. FRONT OVER THE GULF WILL ATTEMPT TO AMPLIFY AND LIFT NWD AS SRN STREAM ENERGY APPROACHES...BUT WILL KEEP POPS SILENT. HIGHS EARLY NEXT WEEK (MON AND TUES) CONTINUE TO WARM INTO THE MID 50S INLAND AND LOW-UPPER 40S COASTAL AREAS THANKS TO COLD WATER. && .AVIATION /20Z WEDNESDAY THROUGH MONDAY/... MORNING LIFR-IFR CONDITIONS HAVE IMPROVED TO MVFR OR EVEN VFR SRN VA TO NE NC IN WAKE OF THIS MORNINGS WARM FRONT. HOWEVER...MVFR- VFR CONDITIONS WILL BE SHORT LIVED AS A COLD FRONT DROPS ACROSS THE REGION LATE TODAY INTO EARLY TONIGHT. BKN-OVC CIGS WITH DECKS AROUND 1500 FT AGL OBSERVED ACROSS CNTRL AND ERN VA...AS WELL AS SE VA. IFR CONDITIONS PREVAIL OVER THE ERN SHORE THANKS TO LOW STRATUS AND FOG. VSBYS HAVE IMPROVED...BUT REMAIN GENERALLY 2-4 MILES. ONLY LIGHT DRIZZLE OBSERVED OVER THE MD ERN SHORE. WINDS GENERALLY S-SW AOB 10 KT NORTH AND 10-15 KT NE NC. FOR THE REST OF THE AFTERNOON...EXPECT TO SEE A FEW BREAKS IN THE CLOUDS ALL AREAS EXCEPT THE ERN SHORE...WHERE IFR CONDITIONS WILL LIKELY PERSIST. HOWEVER...AS THE FRONT DROPS INTO THE REGION...EXPECT CIGS AND VSBYS TO LOWER BACK TO LATE TODAY AND THEN BACK TO IFR THIS EVENING. POST FRONTAL/OVERRUNNING RAIN EXPECTED TO IMPACT SE VA/NE NC BTWN 06 AND 09Z. PRECIP WILL BE IN THE FORM OF RAIN TONIGHT...BUT BY EARLY THURS MORNING A WINTRY MIX OF PRECIP IS EXPECTED. THERE MAY BE A BRIEF PERIOD OF FREEZING RAIN BEFORE THE CAA CHANGES THE RAIN OVER TO SLEET THURS MORNING AND SNOW BY THURS AFTERNOON. SNOWFALL ACCUMULATIONS WILL RANGE FROM 3-5 INCHES IN THE FAR NORTH TO AROUND 1 INCH IN THE SOUTH. NORTH WINDS BEHIND THE FRONT INCREASE TO 10-15 KT LATE TONIGHT THRU THURS...WITH A FEW GUSTS OF 25 KT NEAR THE COAST. HIGH PRESSURE THEN BUILDS IN WITH DRY WEATHER FRIDAY THROUGH SUNDAY. && .MARINE... HAVE EXTENDED DENSE FOG ADVISORIES NWD TO INCLUDE THE ENTIRE BAY...ERN VA RIVES AND COASTAL WATERS TO CHINCOTEAGUE AS WAA OVERSPREADS COLD WATERS. WAA WILL WANE THROUGH THE AFTERNOON...ALLOWING VISIBILITIES TO IMPROVE. MAY NEED TO EXTEND THE DENSE FOG HEADLINES WITH THE NEXT UPDATE. SW WINDS HAVE DIMINISHED THIS MORNING AS THE STRONGEST GRADIENT WINDS PUSH OFFSHORE. SEAS HAVE SUBSIDED BELOW 5 FT EXCEPT IN THE SRN COASTAL WATERS WHERE SE SWELL HAS HELPED MAINTAIN SCA CONDITIONS. HAVE OPTED TO ISSUE SCA HEADLINES SOUTH OF CAPE CHARLES LIGHT FOR TODAY...AS SEAS WILL REMAIN 4-5 FT. .PREV DISCUSSION... A COLD FRNT APPROACHES FM THE W TDA WITH S/SW FLOW CONTINUING OUT AHEAD OF THE FRNT. WINDS MAY COME CLOSE TO SCA THRESHOLDS THIS MORNG OVER THE LWR BAY DUE TO A STRONG LLJ...BUT WAA AND COLD WATERS WILL CAUSE A SHARP INVERSION THAT SHOULD KEEP SUSTAINED WINDS UP TO ~15 KT THERE. ISSUED A DENSE FOG ADVSRY FOR CSTL WTRS S OF CAPE CHARLES LIGHT DUE TO EXPECTED VSBYS AOB 1 MI THRU THE MIDDAY HRS IN ASSOCIATION WITH VERY MOIST LO LEVELS. THE FRNT SLOWLY DROPS THRU THE AREA LATE TDA INTO TNGT AS A WAVE OF LO PRES DEVELOPS ALONG THE FRNT. AS THE FRNT FINALLY PUSHES S OF THE AREA TNGT...SCA CONDS WILL COMMENCE OVR THE WTRS. THESE CONDS WILL CONTINUE INTO THU NGT AS WELL SO EXTENDED THE HEADLINES INTO THE 4TH PERIOD. WINDS MAY COME CLOSE TO GALE FORCE OVR SRN CSTL WTRS BUT CONFIDENCE IS NOT HI ENUF TO ISSUE A GALE WATCH/WARNG ATTM. ALSO KEPT ALL RIVER ZONES EXCEPT THE LWR JAMES OUT OF THE ADVSRY FOR NOW BUT WILL CONTINUE TO MONITOR. WAVES OVER THE BAY UP TO 4-5 FT WITH SEAS OVER CSTL WTRS UP TO 7-8 FT. SFC HI PRES THEN BLDS IN FOR FRI INTO THE WEEKEND LEADING TO IMPROVING MARINE CONDS. && .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...WINTER STORM WARNING FROM 6 AM THURSDAY TO MIDNIGHT EST THURSDAY NIGHT FOR MDZ021>025. NC...NONE. VA...WINTER WEATHER ADVISORY FROM 6 AM THURSDAY TO MIDNIGHT EST THURSDAY NIGHT FOR VAZ060>062-067>073-077-078-080>086-090- 099. WINTER STORM WARNING FROM 6 AM THURSDAY TO MIDNIGHT EST THURSDAY NIGHT FOR VAZ048-049-063-064-074>076. MARINE...DENSE FOG ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR ANZ630>638-652-654-656-658. SMALL CRAFT ADVISORY UNTIL 4 AM EST FRIDAY FOR ANZ650-652-654- 656-658. SMALL CRAFT ADVISORY FROM 4 AM THURSDAY TO 4 AM EST FRIDAY FOR ANZ630>632-634. SMALL CRAFT ADVISORY FROM 7 AM THURSDAY TO 4 AM EST FRIDAY FOR ANZ633-638.
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&& $$ SYNOPSIS...MAM NEAR TERM...AJZ/MAM SHORT TERM...SAM LONG TERM...SAM AVIATION...SAM MARINE...MAS/SAM

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