Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 240227 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1027 PM EDT THU APR 23 2015 .SYNOPSIS... CANADIAN HIGH PRESSURE SLOWLY BUILDS INTO THE REGION THROUGH FRIDAY. A WARM FRONT LIFTS INTO THE CAROLINAS ON SATURDAY AS LOW PRESSURE APPROACHES FROM THE WEST. LOW PRESSURE CROSSES THE REGION SATURDAY NIGHT...PUSHING OFFSHORE SUNDAY. HIGH PRESSURE RETURNS EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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A SHORTWAVE TROUGH ROUNDS THE BASE OF AN UPPER LOW AS IT DROPS INTO THE NRN MID-ATLANTIC REGION TONIGHT. SOME MODELS ATTEMPT TO SQUEEZE OUT SOME PRECIP...BUT DRY LOW LEVELS AND PWATS AOB 0.30 INCHES WILL PREVENT ANYTHING MORE THAN MID LEVEL CLOUDS. WHILE DEWPOINTS WILL REMAIN LOW...LIGHT MIXING AND A PARTLY CLOUDY SKY WILL PREVENT THE BOTTOM FROM DROPPING OUT OF THE TEMPS. LOWS PROGGED TO BE IN THE MID-UPPER 30S INTERIOR VA/NC AND UPPER 30S-LOW 40S NEAR THE COAST. SOME LOW-LYING RURAL LOCALES MAY DROP TO NEAR FREEZING...BUT DRY CONDITIONS AND LIGHT MIXING WILL LIKELY INHIBIT FROST FROM DEVELOPING.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... SHORTWAVE ENERGY SLIDES OFF THE DELMARVA COAST FRI MORNING...RESULTING IN NWLY FLOW ALOFT OVER THE MID ATLANTIC. CONFLUENCE ALOFT WILL ALLOW COOL/CANADIAN HIGH PRESSURE TO BUILD EWD...LOCATING OVER THE REGION LATE FRI. THE RESULT WILL BE ANOTHER DAY OF DRY CONDITIONS AND BELOW NORMAL TEMPS. H85 TEMPS BTWN -2C AND +2C (-1 STD DEV) AND THICKNESSES YIELD TEMPS IN THE MID 60S INLAND AND UPPER 50S TO LOW 60S ERN SHORE AND COASTAL AREAS (-1 STD DEV). NOT AS BREEZY...WITH GUSTS OF 20 TO 25 MPH ACROSS THE N AND NE. MID-LEVEL RIDGE AXIS LOCATES FROM THE OH VALLEY TO THE SE COASTAL PLAINS SAT NIGHT AS SFC HIGH PRESSURE PUSHES OFFSHORE. MID LEVEL MOISTURE RETURN IN ADVANCE OF AN APPROACHING LOW PRESSURE SYSTEM WILL RESULT IN INCREASING MID-UPPER CLOUDS LATE SAT NIGHT. NOT AS COLD...WITH LOWS IN THE UPPER 30S N TO MID 40S SOUTH. INTERIOR MD ERN SHORE LOCALES COULD DROP INTO THE MID 30S...WHERE SKIES WILL REMAIN MOSTLY CLEAR. SHORTWAVE ENERGY DEAMPLIFIES AS IT MOVES INTO THE OH/TN VALLEYS SAT. ASSOCIATED SFC LOW LOCATES OVER THE OH VALLEY. INCREASING/AMPLIFYING FLOW OVER THE SE CONUS WILL LIFT THE STALLED BOUNDARY OVER THE GULF STATES NWD AS A WARM FRONT. MOISTURE ALSO RETURNS IN EARNEST LATE SAT...COINCIDING WITH BEST ISENTROPIC LIFT. EXPECT RAIN TO SPREAD OVER THE PIEDMONT INTO CNTRL/ERN VA SAT AFTERNOON. POPS REMAIN LIKELY OVER THE AREA...EXCEPT CHANCE OVER THE MD ERN SHORE. BETTER LIFT FROM THE WEAKENING SHORTWAVE ARRIVES SAT NIGHT. SRN STREAM ENERGY LIFTING FROM THE GULF STATES SAT NIGHT WILL LIKELY DEVELOP A WAVE OF LOW PRESSURE ALONG THE LIFTING WARM FRONT AS THE ORIGINAL LOW WEAKENS OVER THE OH VALLEY. TRENDED FORECAST AWAY FROM THE 23/12Z GFS AS IT KEEPS THE INLAND LOW MUCH STRONGER THAN THE COASTAL LOW. THIS DOESNT MATCH PV AND THETA-E FIELDS...AS THEY WOULD FAVOR COASTAL LOW DEVELOPMENT. THUS TRENDED FORECAST TOWARD 23/15Z SREF AND 23/12Z ECMWF GUIDANCE. THIS SOLUTIONS PUTS THE BEST LIFT ALONG THE INTERSTATE 64 CORRIDOR SUNDAY MORNING AS THE INLAND SFC LOW DISSIPATES. COASTAL LOW STRENGTHENS...WITH CHANCES FOR LIGHT RAIN CONTINUING THRU SUN MORNING. BEST CHANCES WILL THEN TRANSFER TO THE COAST (ERN VA/NE NC) SUN AFTERNOON. LIFT IS RATHER MODEST...ALONG WITH PWATS ONLY AROUND 1 INCH ACROSS THE REGION. THUS...EXPECT ONLY LIGHT TO MODERATE RAIN WITH RAINFALL AMOUNTS GENERALLY BTWN ONE QUARTER AND ONE HALF INCH (HIGHEST IN THE SOUTH). COOL/DAMP/CLOUDY CONDITIONS WILL RESULT IN HIGHS IN THE MID-UPPER 50S (-1 TO -1.5 STD DEV) SAT AND LOWS IN THE MID 40S TO LOW 50S SAT NIGHT. CLOUDY SKIES PERSIST SUN WITH HIGHS IN THE LOW 60S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... MEDIUM RANGE PERIOD BEGINS WITH AN UPPER LOW CENTERED FROM ERN NY STATE INTO NEW ENGLAND AND WEAK UPPER LEVEL RIDGING OVER THE LOWER MS VALLEY. ANOTHER UPPER LOW IN PLACE ACRS THE SW CONUS. OVERALL...THIS SOMEWHAT "BLOCKY" PATTERN WILL MAKE FOR SLOW MOVEMENT OF UPPER LEVEL FEATURES THROUGH THE MIDDLE OF NEXT WEEK. THE UPPER LOW TO OUR NE LOOKS TO BE THE STRONGEST FEATURE...AND GFS/ECMWF IN GOOD AGREEMENT THAT ANOTHER SHORTWAVE WILL ROTATE AROUND THE BASE OF THIS TROUGH/UPPER LOW ON MON. LOCAL AREA WILL BE ON BACKSIDE OF THE UPPER LOW SUN NIGHT/MON SO A DRYING TREND WILL COMMENCE. TEMPERATURES MON LOOK TO REMAIN COOLER THAN AVG WITH HIGHS MAINLY IN THE 60S AFTER AM LOWS IN THE 40S TO AROUND 50 F. WILL CARRY A 20% POP ACRS THE MD ERN SHORE AS THIS AREA WILL BE NE OF THE TRACK OF THE SHORTWAVE. SKIES AVG PARTLY SUNNY MOST AREAS...TRENDING TO MOSTLY CLOUDY IN THE NE. AS UPPER RIDGING OVER THE WRN CONUS SHIFTS NE FROM THE NRN ROCKIES TO THE NRN PLAINS LATER TUE/WED...THE UPPER LOW WILL GRADUALLY WEAKEN/SHIFT OFF THE EAST COAST. MID ATLC REGION LOOKS TO BE LOCATED IN BETWEEN SYSTEMS TUE INTO EARLY WED WITH WEAK SFC HIGH PRESSURE OVER THE AREA. WILL HAVE DRY CONDITIONS AND PARTLY /MOSTLY SUNNY SKIES. REMAINING COOL WITH HIGHS GENLY REMAINING IN THE 60S...PERHAPS ONLY THE UPPER 50S AT THE ATLC COAST. LOWS AVG IN THE UPPER 30S TO MID 40S. EXPECT INCREASING SW FLOW ALOFT LATER WED INTO THU...BRINGING OVERRUNNING AND A CHANCE FOR PRECIP STARTING LATER WED AND LASTING INTO THU. GFS/ECMWF NOW DEVELOP A COASTAL SFC LOW BY THU. HAVE POPS IN THE 30-40% RANGE FROM LATER WED THROUGH THU ALTHOUGH STILL A LOT OF UNCERTAINTY AS THIS IS LATE DAY6/DAY 7. HIGHS IN THE UPPER 50S TO THE 60S AND LOWS IN THE UPPER 40S TO THE 50S. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... DRY/VFR CONDS WILL CONTINUE INTO SAT AS HIGH PRESSURE BUILDS IN FROM THE WNW. GUSTY WINDS WILL DIMINISH TO LIGHT EARLY THIS EVENING...THEN PICKUP SOME AFTER MIDNIGHT AS LOW PRESSURE PASSES TO THE NORTH. WINDS WILL ESPECIALLY BECOME GUSTY NEAR THE COAST OVERNIGHT. REMAINING BREEZY AGAIN ON FRI...ESPECIALLY AT KSBY WITH GUSTS 25-30 KT...GENLY 20-25 KT ELSEWHERE. GOOD CHANCE FOR RAIN LATER SAT INTO SUNDAY. IMPROVING CONDITIONS LATE SUN THROUGH MON. && .MARINE... WINDS OVER THE BAY HAVE BEEN BORDERLINE SCA OFF AN ON THIS AFTERNOON DUE TO MIXING WITH THE STRONGER GUSTS OCCURRING WITHIN A COUPLE MILES OF SHORE OR AT ELEVATED SENSORS. HIGH RES MODELS ALL SUGGEST WINDS WILL DECREASE A FEW KTS TEMPORARILY THROUGH 10 PM. A COLD FRONT WILL PUSH SOUTH ACROSS THE ENTIRE AREA OVERNIGHT RESULTING IN SCA CONDITIONS ON ALL WATERS. THE COMBINATION OF CAA AND RELATIVELY WARMER WATERS IN THE MID 50S TO AROUND 60 WILL ALLOW OVERNIGHT MIXING OVER THE WATERS TO PUSH WINDS TO 15 TO 25 KT WITH SOME GUSTS TO AROUND 30 KT FOR A BRIEF TIME DURING THE EARLY MORNING HOURS FRIDAY. HIGH PRES SLOWLY BUILDS OVR THE WATERS THROUGH FRI AFTERNOON AND FRIDAY NIGHT WITH CONDITIONS FALLING BELOW SCA SOME TIME IN THE AFTERNOON. SUB-SCA MARINE CONDITIONS PREVAIL FRIDAY NIGHT THROUGH SATURDAY WITH WITH WEAK HIGH PRESSURE OVER THE AREA. A WEAK SFC LOW DEVELOPS OVER THE OHO RIVER VALLEY AND PASSES ACROSS VA AND OFFSHORE SUNDAY. VARIABLE WINDS SUNDAY BECOME NW SUNDAY EVENING AS THE LOW MOVES OFFSHORE. THERE IS A CHC THAT WINDS COULD INCREASE TO LOW END SCA LATE SUNDAY, BUT EXPECT PREDOMINATE SUB-SCA CONDITIONS THROUGHOUT THE WEEKEND. && .FIRE WEATHER... COOL DRY AIRMASS REMAINS OVER THE REGION FRI. MINIMUM RH VALUES ARE FORECAST TO RANGE FROM 20-30 PCT...WITH NWLY WINDS 10-15 MPH WITH GUSTS OF 20-25 MPH. STRONGEST GUSTS EXPECTED ACROSS THE NRN NECK AND ERN SHORE. FUELS HAVE HAD ANOTHER DAY TO DRY...BUT STILL REMAIN MARGINAL. NO HEADLINES ARE PLANNED ATTM AS SPS STILL REMAINS OUT FOR MD ERN SHORE. WILL READDRESS TONIGHT. RECENT RAINFALL AND GREEN-UP CONTINUE TO BE LIMITING FACTORS. LIGHT WINDS AND INCREASING MOISTURE SAT WILL NEGATE FIRE WEATHER CONCERNS. WIDESPREAD RAINFALL IS EXPECTED SAT AFTERNOON THRU SUN. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT FRIDAY FOR ANZ630>638-650- 652-654-656-658. && $$ SYNOPSIS...MAS/SAM NEAR TERM...MAS/SAM SHORT TERM...MAS/SAM LONG TERM...LKB AVIATION...LKB/JEF MARINE...LKB FIRE WEATHER...

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