Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 230752 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 352 AM EDT WED APR 23 2014 .SYNOPSIS...
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A COLD FRONT WILL CROSS THE REGION EARLY THIS MORNING. COOL CANADIAN HIGH PRESSURE BUILDS BACK OVER THE REGION TONIGHT AND THURSDAY. A SERIES OF WEAK FRONTS WILL CROSS THE AREA FRIDAY INTO THE WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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LATEST WX ANALYSIS FEATURES SFC COLD FRONT SLOWLY DROPPING SOUTHEAST ACROSS THE LOWER MID-ATLANTIC THIS MORNING. EXPECT QUICK CLEARING BEHIND THE FRONT THROUGH SUNRISE AS WINDS VEER AROUND TO THE NW, AND WILL BECOME GUSTY LATER TODAY. MODIFYING CANADIAN HIGH PRESSURE BUILDS TO OUR NW TODAY. BUFKIT SOUNDINGS SUGGEST WINDS IN THE 15 TO 20 MPH RANGE, WITH FREQUENT GUSTS TO 35-40 MPH ON THE ERN SHORE AND 25-35 MPH ELSEWHERE. A MAINLY SUNNY/CLEAR SKY EXPECTED, ALTHOUGH A FEW SCATTERED CU WILL PERSIST ACROSS THE ERN SHORE DUE TO COLD POOL ALOFT ON THE BACK SIDE OF THE SHORTWAVE TROUGH. PLENTY OF SUN, DRYING FUELS AND GUSTY WINDS WILL ADD UP TO A POTENTIALLY CRITICAL FIRE WEATHER DAY,. HAVE ISSUED A RED FLAG WARNING FOR NORTHERN HALF OF THE AREA, MAINLY FROM RIC NORTH, WITH AN SPS FOR INCREASED FIRE DANGER OUTLOOKED OVER SOUTHERN HALF OF THE AREA. FOR TEMPS, LOCAL THICKNESS TOOLS INDICATE HIGHS ONLY IN THE LOWER TO MIDDLE 60S OVER THE LOCAL AREA. HOWEVER, WITH DEWPOINTS MIXING INTO THE UPR 20S/LOW 30S (YIELDING MINIMUM RH VALUES IN THE MID 20S INLAND) AND WITH DOWNSLOPE FLOW COMPONENT, EXPECT MAXIMA MAINLY IN THE MID TO UPPER 60S INLAND ALL ZONES (NOT MUCH DIFFERENCE AT THE COAST DUE TO STRONG NW FLOW). HIGH PRESSURE BUILDS INTO THE REGION TONIGHT. EXPECT CHILLY EARLY MORNING LOWS THU MORNING IN THE MID-UPPER 30S ALONG/W OF I-95 TO THE UPPER 30S TO LOWER 40S ELSEWHERE UNDER A MAINLY CLEAR SKY. DO NOT EXPECT ANY FREEZE ISSUES AND PROBABLY TOO DRY FOR MUCH MORE THAN SOME PATCHY FROST IN SHELTERED LOCALES.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
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DRY AGAIN ONCE AGAIN THU AS HIGH PRESSURE SLIDES OVER THE NORTHEAST/MID-ATLANTIC REGION, BEFORE SLIDING OFF THE ATLANTIC SEABOARD ERY FRIDAY. HIGHS THURS GENERALLY IN THE UPPER 60S (A LITTLE COOLER NEAR THE COAST). ONCE AGAIN, MIN RH VALUES FALL INTO THE 20S THU AFTN BUT WINDS WILL BE LIGHTER. NEXT FAST MOVING WAVE OF MOISTURE MOVES IN FROM THE PLAINS ON FRI. GFS REMAINS FASTER WITH BRINGING SYSTEM THROUGH, WITH THE NAM/ECMWF A BIT SHARPER WITH THE UPPER WAVE...AND HENCE A BIT SLOWER. PUSHED BACK ONSET OF POP JUST SLIGHTLY AND CONTINUED TO SPLIT THE DIFFERENCE BETWEEN THESE STILL DIVERGENT SOLUTIONS. GIVEN THIS, EXPECT A SCENARIO NOT UNLIKE THAT OF EARLIER YESTERDAY (TUESDAY); RATHER MEAGER INSTABILITY WITH MODEST DEEP LAYER SHEAR/LAPSE RATES THAT RESULT IN SOME WEAK DISORGANIZED CONVECTION LATE IN THE DAY FRIDAY. WILL KEEP CHC POPS ALL ZONES FOR SCT SHRAS AND PERHAPS A THUNDERSTORM PUSHING THROUGH AT SOME POINT IN THE AFTN/EVENING. WARMER SSW FLOW SHOULD PUSH HIGHS WELL INTO THE 70S TO NEAR 8O. CLEARING BEHIND THE FRONT FRIDAY NIGHT, WITH POPS QUICKLY ENDING WEST TO EAST. LOWS GENERALLY IN THE 50S TO NEAR 60 ALONG AREA COASTLINES.
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&& .LONG TERM /SATURDAY THROUGH TUESDAY/... PROGRESSIVE FLOW WILL BEGIN TO EVOLVE INTO A HIGHLY AMPLIFIED/BLOCKY PATTERN OVER THE CONUS DURING THE EXTENDED...LIKELY RESULTING IN A COOL/WET PERIOD BY EARLY NEXT WEEK. MEDIUM RANGE GUIDANCE TENDS TO STRUGGLE WITH BLOCKY FLOW...AND THIS IS NO EXCEPTION. TRENDED TOWARD ENSEMBLE AND WPC GUIDANCE TO SMOOTH OUT DIFFERENCES IN THE MODELS. OVERALL...UPPER PATTERN WILL BE CHARACTERIZED BY AN ANOMALOUS UPPER TROUGH OVER THE WRN CONUS...HIGH PRESSURE RIDGING FROM THE GULF STATES INTO THE NORTHWEST TERRITORIES AND ANOTHER UPPER TROUGH OVER SE CANADA AND NEW ENGLAND. WHILE MEANINGFUL DIFFERENCES EXIST IN THE MODELS...A SECOND (DRY) COLD FRONT IS PROGGED TO CROSS THE LOCAL AREA ON SAT. THIS FRONT WILL BRING COOLER/DRIER AIR TO THE REGION ON SUN. A STATIONARY BOUNDARY WILL THEN SET UP OVER THE MID-ATLANTIC REGION (DEPENDING ON THE MODEL IT COULD BE FROM THE CAROLINAS NWD TO THE MASON DIXON LINE). THIS BOUNDARY WILL BE THE FOCUS OF PRECIP EARLY NEXT WEEK. MEANWHILE...A BROAD AREA OF LOW PRESSURE OVER THE PLAINS WILL PROGRESS EWD SUN-TUES...TAPPING INTO GULF MOISTURE. WILL MAINTAIN SLIGHT CHANCE POPS SUN NIGHT-TUES BASED ON UNCERTAINTY...BUT INCREASE TO LOW-END CHANCE POPS TUES NIGHT AS THE UPPER/SFC LOW GETS CLOSER. HAVE TRENDED TO THE COOLER SIDE OF GUIDANCE WITH HIGHS GENERALLY IN THE MID-UPPER 60S SUN-TUES. OVERNIGHT LOWS GENERALLY IN THE UPPER 40S-LOW 50S. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... AS OF 23Z...PRE-FRONTAL SHOWERS HAVE PRACTICALLY DISSIPATED AND DID NOT INCLUDE ANY PCPN IN THE TAFS. A STRONG COLD FRONT WAS MOVING THROUGH THE MOUNTAINS AND IS FORECAST TO REACH RIC/SBY SHORTLY AFTER MIDNIGHT AND ECG AROUND 09Z/5AM EDT. BKN MID LEVEL CLOUDS SHOULD QUICKLY CLEAR BEHIND THE FRONT. GUSTY NW OR N WINDS WILL IMMEDIATELY FOLLOW THE FRONT. WINDS DIMINISH SOME (EXCEPT AT ORF) A COUPLE OF HOURS FOLLOWING THE FRONTAL PASSAGE AND THEN INCREASE ONCE AGAIN LATE WEDNESDAY MORNING. GUSTS MAY REACH OVER 30 KNOTS AT SBY AND AROUND 25 KNOTS AT THE OTHER TAF SITES. OUTLOOK...VFR CONDITIONS WILL CONTINUE THROUGH THURSDAY NIGHT. THE NEXT COLD FRONT CROSSES THE AREA FRIDAY WITH SCT SHWRS/TSTMS IN THE AFTERNOON. ANOTHER FRONT CROSSES THE AREA SATURDAY BUT THE WEEKEND IS FORECAST TO BE DRY. && .MARINE... PRE-FRONTAL TROUGH HAS ALIGNED ALONG THE WATERS LATE THIS AFTERNOON AS A COLD FRONT LOCATES OVER THE CNTRL APPALACHIANS. S-SW WINDS CURRENTLY OVER THE WATERS AVERAGING 10-15 KT WITH WAVES 1-2 FT AND SEAS 3-4 FT. COLD FRONT WILL CROSS THE WATERS THIS EVENING AS A STRONG NW SURGE COMMENCES. PRESSURE GRADIENT STRENGTHENS BTWN BUILDING CANADIAN HIGH PRESSURE OVER THE GREAT LAKES AND THE DEPARTING COLD FRONT. 925MB WINDS INCREASE TO 35-40 KT AS LOW LEVEL LAPSE RATES SHARPEN. THE RESULT WILL BE SOLID SCA CONDITIONS OVER THE WATERS...INCLUDING THE RIVERS AND SOUND. DECIDED TO NOT GO LOW-END GALE BASED ON THE LIMITED STRENGTH OF THE SFC PRESSURE GRADIENT AND COOL WATERS. HOWEVER...AN OCCASIONAL GUST TO 35 KT IS POSSIBLE...ESPECIALLY OVER THE NRN BAY AND NRN COASTAL WATERS. TOP OF THE MIXED LAYER AT KSBY YIELDS GUST TO ONLY 30-33 KT. WILL MONITOR FUTURE OBS/MODEL TRENDS TO SEE IF GALE HEADLINES ARE NEEDED. REGARDLESS...CONDITIONS WILL DETERIORATE RAPIDLY AROUND MIDNIGHT. WAVES WILL BUILD TO 3-5 FT IN THE BAY...2-3 FT IN THE RIVERS AND 2 FT IN THE SOUND. SEAS WILL BUILD TO 5-8 FT...HIGHEST IN THE NRN COASTAL WATERS. HIGH PRESSURE WILL CONTINUE TO BUILD SWD OVER THE OH VALLEY WEDS AS SCA CONDITIONS PERSIST THRU THE DAY. THE HIGH WILL NUDGE OVER THE WATERS WED NIGHT...ALLOWING THE PRESSURE GRADIENT TO RELAX AND WINDS TO DIMINISH. SCA HIGH PRESSURE WILL SLIDE OVER THE REGION THURS...LOCATING OFFSHORE LATE THURS. FLOW WILL RETURN TO THE SOUTH...WITH SEAS SUBSIDING BELOW 5 FT LATE THURS. SCA HEADLINES FOR THE RIVERS AND SOUND DROP OFF LATE WEDS...LOWER JAMES AND BAY THURS MORNING. A WEAKER COLD FRONT CROSSES THE WATERS FRI AFTERNOON WITH A SECOND COLDER FRONT CROSSING THE WATERS SATURDAY. SCA CONDITIONS MAY BE POSSIBLE SAT NIGHT. && .FIRE WEATHER...
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GIVEN THE EXPECTED DRY AND BREEZY CONDITIONS LATER TODAY...AND IN COORDINATION WITH STATE FIRE OFFICIALS/NEIGHBORING FORECAST OFFICES, A RED FLAG WARNING HAS BEEN ISSUED FOR THIS AFTERNOON/EVENING FOR PORTIONS OF CENTRAL AND EASTERN VA (MAINLY ALONG AND NORTH OF RIC METRO AREA, AS WELL AS THE LOWER MD EASTER SHORE. WINDS ARE EXPECTED TO BE THE STRONGEST THIS AFTN (20-25 MPH WITH GUSTS TO 35-40 MPH) ALONG AND NORTH OF A LINE FROM FVX-PTB-LFI...AND THIS IS ESSENTIALLY THE WARNING AREA. FARTHER SOUTH...WINDS WILL NOT BE AS STRONG (10-20 MPH WITH GUSTS TO 30 MPH)...SO HAVE OPTED TO ISSUE AN SPS FOR INCREASED FIRE DANGER OVER THESE AREAS TO HIGHLIGHT DRYING FUELS. DRY CONDITIONS (MIN RH VALUES 20-25%) WILL OCCUR AGAIN ON THURSDAY. HOWEVER...WINDS ARE NOT EXPECTED TO BE AS STRONG. THIS WILL LIKELY PRECLUDE THE NEED FOR ANY FIRE WX WATCHES/WARNINGS OVER OUR AREA...EXCEPT FOR THE LOWER MD EASTERN SHORE WHERE WINDS MAY REMAIN ELEVATED. HOWEVER, ANYONE PLANNING/INVOLVED IN OUTDOOR BURNING ACTIVITIES SHOULD CONTINUE TO EXERCISE CAUTION. WILL THEREFORE MENTION CONTINUED DRY CONDITIONS FOR TOMORROW IN THE HWO/FWF.
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&& .AKQ WATCHES/WARNINGS/ADVISORIES...
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MD...RED FLAG WARNING FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR MDZ021>025. NC...INCREASED FIRE DANGER FROM NOON EDT TODAY THROUGH THIS EVENING FOR NCZ012>017-030>032. VA...RED FLAG WARNING FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR VAZ048-049-061>064-068>078-081>086-089>091-094-099-100. INCREASED FIRE DANGER FROM NOON EDT TODAY THROUGH THIS EVENING FOR VAZ060-065>067-079-080-087-088-092-093-095>098. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THURSDAY FOR ANZ650-652- 654-656-658. SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ633- 635>637. SMALL CRAFT ADVISORY UNTIL 10 AM EDT THURSDAY FOR ANZ630>632- 634. SMALL CRAFT ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR ANZ638.
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&& $$ SYNOPSIS...LKB/MAM NEAR TERM...MAM SHORT TERM...LKB/MAM LONG TERM...SAM AVIATION...LSA MARINE...SAM FIRE WEATHER...

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