Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 210759 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 359 AM EDT TUE OCT 21 2014 .SYNOPSIS... LOW PRESSURE MOVES THROUGH THE REGION TODAY...LOCATING OFF THE NORTHEAST COAST FOR MUCH OF THE MID TO LATE WEEK PERIOD. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LATEST ANALYSIS SHOWING SFC LOW PRESSURE OVER LAKE ONTARIO WITH A TRAILING SFC COLD FRONT EXTENDING SW FROM THE LOW DOWN THROUGH THE OH VALLEY. WEAK/ELONGATED SHORTWAVE ALOFT IS PUSHING EAST ACRS THE CWA AND HAS ALLOWED FOR ENOUGH LIFT TO DEVELOP SOME VERY LIGHT SHOWERS/SPRINKLES OVER THE REGION (GENLY TOO DRY IN LOW LEVELS FOR ANYTHING MEASURABLE THUS FAR). MOISTURE WILL TEND TO DIMINISH FROM W TO E THROUGH 12Z AS DRY SLOT PUSHES BACK IN FROM THE SW BUT WILL MAINTAIN 20% POPS E OF I-95 THROUGH 12Z. AFTER 12Z...WILL TEND TO SALVAGE A PRETTY NICE DAY ACRS MOST OF THE LOCAL AREA AS SKIES BECOME PARTLY TO MOSTLY SUNNY AND WINDS SHIFT TO THE WEST. WITH TEMPERATURES STARTING OFF MUCH MILDER THAN YESTERDAY MORNING...SUN AND MIXING SHOULD ALLOW FOR FAIRLY RAPID WARMING THROUGH THE 60S AND INTO THE LOWER 70S BY EARLY AFTN. WITH A STRONG SHORTWAVE CURRENTLY SEEN ON WV SATELLITE OVER THE WESTERN GREAT LAKES PROGGED TO DIVE SE AROUND THE BASE OF THE AMPLIFYING UPPER LOW...EXPECT INCREASING CLOUDS FROM NW TO SE THIS AFTN. HIGH RES MODELS SHOWING A FAIRLY SIGNIFICANT AMOUNT OF SIMULATED REFLECTIVITY ACRS NW PORTIONS OF THE CWA AFTER 18Z...GRADUALLY ADVECTING THIS SE TO THE COAST PRIOR TO 00Z THIS EVENING. DUE TO DRY LOW LEVELS (DEW PTS IN 40S)...EXPECT THAT RADAR COVERAGE THIS AFTN WILL LOOK MORE IMPRESSIVE THAN REALITY AND THUS WILL KEEP POPS CAPPED IN CHANCE RANGE...AROUND 40% ACRS THE NORTH AFTER 20Z...TAPERED TO 20% OR LOWER ACRS THE SOUTH. QPF AMOUNTS WILL BE LIGHT...< .10". HIGHS TODAY WILL RANGE FROM THE MID TO UPPER 70S ACRS THE FAR SE (WHERE CLOUDS ARE SLOWER TO PUSH IN THIS AFTN)...TO THE UPPER 60S/AROUND 70 F OVER THE NW DUE TO EARLIER ONSET OF CLOUDS AN POTENTIAL SHOWERS. ALSO...DUE TO THE LOW DEW PTS...IF MEASURABLE RAINFALL DOES OCCUR...TEMPS LATE THIS AFTN WOULD POTENTIALLY DROP INTO THE LOWER 60S OR COOLER. && .SHORT TERM /6 PM THIS EVENING THROUGH THURSDAY/...
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FLOW CONTINUES TO AMPLIFY THROUGH THE PERIOD AS A BLOCKING PATTERN DEVELOPS OVER ERN CANADA. THE UPPER LOW WILL PROGRESS SLOWLY EWD OVERNIGHT INTO WED...LOCATING OFF THE DELMARVA COAST LATE WED. WITH THE UPR LOW PIVOTING ACROSS THE LOCAL AREA TONIGHT...WILL SEE A BETTER CHANCE FOR SHOWERS DEVELOP ESPECIALLY NORTH/NE WHERE BEST UPWARD MOTION IS ANTICIPATED. HAVE BUMPED POPS UP TO LIKELY IN THESE AREAS...TAPERED TO LOWER CHANCES FARTHER S/W WHERE DEEP MOISTURE IS GENLY NOT PRESENT. LOWS TUE NIGHT IN THE UPPER 40S TO MID 50S. DEEP UPPER TROUGH/CLOSED LOW SLOWLY MOVES EAST AND OFFSHORE WED. FORECAST SOUNDINGS FAIRLY DRY ALOFT OVER INLAND SECTIONS AS THE TROUGH/SFC REFLECTION SWING OFFSHORE...HOWEVER A FAIRLY SHARP MOSITURE GRADIENT PROGGED ALONG THE COAST...THE ERN SHORE IN PARTICULAR. WILL THEREFORE KEEP CHC POPS LIMITED TO AREAS MAINLY ALONG AND NE OF THE I-64 CORRIDOR WED...WITH EMPHASIS OF 60-70% POPS ON THE EASTERN SHORE. COULD END UP BEING DRY OVER FAR SW ZONES. FAVOR COOLER END OF GUIDANCE FOR HIGHS...MID 60S SW TO AROUND 60/LOWER 60S NE. THE CLOSED LOW MOVES FARTHER NE WED NIGHT INTO THU...LOCATING OFF THE NEW ENGLAND COAST BY 00Z FRIDAY. ANY LEFTOVER SHOWER CHANCES BY THEN WILL BE LIMITED TO THE EASTERN SHORE (20%). DECREASING CLOUDS ARE ALSO EXPECTED ACROSS INTERIOR VA. LOWS WED NIGHT IN THE LOW 40S TO LOW 50S. COOL AGAIN THU ALTHOUGH WITH A BIT MORE SUN SHOULD SEE HIGHS INTO THE MID-UPPER 60S WELL INLAND WITH HIGHS ONLY IN THE LOWER 60S FARTHER NE.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... LOW PRESSURE LIFTS TO THE NE THURSDAY NIGHT THROUGH SATURDAY AS UPPER RIDGING EXPANDS EASTWARD FROM THE CENTRAL US. A WEAK TROUGH CLIPS THE NRN MID-ATLANTIC SATURDAY NIGHT AND QUICKLY MOVES OFF THE COAST SUNDAY. MID/UPPER LEVEL RIDGING BUILDS OVER THE ERN US EARLY NEXT WEEK. OVERALL...DRY CONDITIONS SHOULD PREVAIL THROUGH THE MEDIUM RANGE PERIOD. HIGH TEMPERATURES SHOULD AVERAGE IN THE MID 60S TO AROUND 70 FRIDAY AND SATURDAY...AND TREND UPWARD INTO THE UPPER 60S TO LOW 70S SUNDAY...AND POTENTIALLY 70-75 BY MONDAY. LOWS SHOULD RANGE FROM THE LOW/MID 40S NW...TO THE LOW/MID 50S FOR SE COASTAL LOCATIONS. && .AVIATION /08Z TUESDAY THROUGH SATURDAY/... EXPECT MAINLY VFR CONDITIONS TODAY INTO THIS EVENG OVR THE TAF SITES...WITH PERIODS OF MID LVL CLOUDINESS...AS A WEAK COLD FRONT MOVES ACRS THE AREA. LATER TNGT THRU THU...LO PRES WILL INTENSIFY OFF THE NEW JERSEY AND NEW ENGLAND CSTS. THERE WILL BE A CHC FOR SHOWERS AND MVFR CIGS...ESPLY OVR NRN AND ERN PORTIONS LATE TNGT INTO WED NGT. MVFR CIGS MAY LINGER INTO EARLY THU AT SBY. THE LO PRES SYSTEM WILL MOVE FARTHER AWAY TO THE NE AND HI PRES BLDS IN FM THE NNW THU NGT INTO SUN. && .MARINE... 10 PM UPDATE...WINDS AND SEAS HAVE INCREASED WELL OFFSHORE (OFF THE MD COAST) ACCORDING TO BUOY 09. SEAS ARE JUST ABOUT 5 FT (4.9 FT LAST TWO HOURS). WINDS AND SEAS ARE MUCH LESS TOWARD THE COAST. INCLUDED A STRIP OF 5 FT SEAS (THROUGH 06Z) IN THE ZONES N OF PARRAMORE ISLAND BUT HOLDING OFF ON SCA FOR NOW. HI RES MODELS ARE OVERDOING THE WINDS OVER THE BAY. AS AIR TEMPERATURES COOL...MIXING WILL INCREASE AND WINDS MAY INCREASE BUT EXPECT THEM TO STAY BELOW SCA CRITERIA. PREVIOUS DISCUSSION... SURFACE HIGH PRESSURE SLIDES OFFSHORE TONIGHT...ALLOWING THE WIND TO REMAIN S/SW. EXPECT SUB-SCA CONDITIONS TO PREVAIL WITH WIND SPEEDS AVERAGING UP TO 15-20 KT ACRS NORTHERN COASTAL WATERS...AND GENERALLY 10-15 KT ELSEWHERE. THE NEXT COLD FRONT WILL SLOWLY CROSS THE COAST LATE TUE AFTERNOON/EVENING...FOLLOWED BY EVENTUAL SCA CONDITIONS LATER WEDNESDAY INTO WEDNESDAY EVENING AS SFC LOW PRESSURE THEN DEEPENS OFF THE COAST. THIS SYSTEM IS EXPECTED TO STALL OFFSHORE THURSDAY THROUGH THE END OF THE WEEK BRINGING A PROLONGED PERIOD OF SCA CONDITIONS. WITH FLOW BEING OFFSHORE FROM THE NW...SEAS WOULD TEND TO STAY CAPPED AT 5-6 FT AND TIDAL FLOODING IS NOT EXPECTED. N/NW FLOW IS EXPECTED TO CONTINUE INTO NEXT WEEKEND WITH SPEEDS DIMINISHING TO 10-15KT AND SEAS SUBSIDING. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...JDM/LKB LONG TERM...AJZ AVIATION...TMG MARINE...AJZ/TMG

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