Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 100243 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1043 PM EDT WED JUL 9 2014 .SYNOPSIS... A COLD FRONT APPROACHES FROM THE NORTHWEST OVERNIGHT...THEN STALLS OVER VIRGINIA AND NORTH CAROLINA THURSDAY INTO FRIDAY. THE FRONT WILL DISSIPATE FRIDAY NIGHT AS HIGH PRESSURE OVER THE NORTHEAST BUILDS SOUTH OFF THE MID ATLANTIC COAST. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... KAKQ/KDOX RADARS SHOWING SHOWERS AND THUNDERSTORMS HAVE LARGELY WEAKENED/DECREASED IN AREAL COVERAGE WITH THE EXCEPTION OF ACROSS NE NC ALONG REMNANT THETA-E RIDGE. LATE EVENING GOES WV SAT IMAGERY SHOWS A DISTURBANCE ROLLING ACROSS THE E TN/WESTERN CAROLINAS, SO HV RETAINED A LOW CHC POP OVERNIGHT ACROSS THE SOUTH...AND MAINLY DRY ELSEWHERE. OTHERWISE, KEPT POPS RATHER CLOSE TO CURRENT OBS, WITH TEMPS FALLING OFF VERY LITTLE OVERNIGHT. LOWS GENERALLY IN THE LOW TO MID 70S UNDER A MOSTLY CLOUDY SKY. PREVIOUS DISCUSSION... LATEST ANALYSIS SHOWING SFC TROUGHINESS OVER THE REGION...WITH A COLD FRONT SITUATED FROM EASTERN NY STATE TO THE OHIO VALLEY. ALOFT...A DEEP UPPER LOW IS CENTERED TO THE SE OF HUDSON BAY. SEVERAL SHORTWAVES ARE MOVING THROUGH THE WSW FLOW ALOFT...THE MOST NOTABLE OVER CENTRAL/WRN NC. AREAS OF CONVECTION HAVE DEVELOPED IN THE WARM/HUMID AIRMASS ACRS THE LOCAL AREA...ONE AFFECTING THE PIEDMONT AND ANOTHER TO THE SE FROM NORTHAMPTON NC TO THE PENINSULA. HAVE GONE WITH LIKELY POPS IN THESE AREAS FOR THE NEXT FEW HRS BASED ON THIS SETUP (WITH GENLY SCATTERED 30-50% COVERAGE ELSEWHERE). A FEW MARGINALLY SEVERE STORMS MAY OCCUR BUT OVERALL MOST OF THESE ARE EXPECTED TO PRODUCE HEAVY RAIN AND BRIEF WIND GUSTS MORE ON THE ORDER OF 30-40 MPH. LATER THIS EVENING...HAVE LIKELY POPS FOCUSED OVER SE VA.INTERIOR NE NC PER LATEST UPSTREAM RADAR AS WELL AS HIGH RES MODEL OUTPUT. WARM/HUMID OVERNIGHT...ALTHOUGH A TAD COOLER THAN PREVIOUS FEW NIGHTS WITH LOWS IN THE UPPER 60S W/NW TO LWR-MID 70S SE. && .SHORT TERM /6 AM THURSDAY THROUGH 6 AM THURSDAY/... GFS/NAM IN GOOD AGREEMENT THAT THE SFC FRONT WILL STALL OVER THE LOCAL AREA ON THU. MAKES SENSE GIVEN A FLATTENING WSW FLOW ALOFT ALIGNING NEARLY PARALLEL WITH THE SFC FRONT. HAVE BUMPED AFTN POPS UP TO LIKELY ACRS SE VA/NE NC...WITH HIGH CHC (50%) IN CENTRAL VA...ALTHOUGH IF TRENDS HOLD COULD SEE THESE AREAS NEEDING LIKELY POPS AS WELL. TEMPS HELD DOWN A BIT DUE TO THE CLOUD COVERAGE/PCPN. HIGHS MAINLY IN THE MID/UPPER 80S. MODELS IN BETTER AGREEMENT IN MOVG S/W ENERGY NE ALONG THE STALLED BNDRY THURS NIGHT THRU ERLY FRIDAY BEFORE HIGH PRESSURE BUILDS IN FROM THE NORTH FRI NIGHT. GIVEN THIS TREND...INCREASED BOTH CLOUD COVERAGE AND POPS FOR THIS PRD. SLOW MOVG...TRAINING ECHOES COULD PRODUCE LCLLY HVY DOWNPOURS ACROSS ESPECIALLY THE SERN HALF OF FA THUS QPF HAS BEEN SIGNIFICANTLY RAISED. LOWS THU NIGHT M60S-L70S. HIGHS FRI M-U80S. TOTAL QPF THRU FRIDAY WILL VARY FROM BTWN 1/4 TO 1/2 INCH ACROSS NWRN CNTYS...1/2 TO 1 INCH ACROSS CNTRL SCTNS OF FA TO BTWN 1-2 INCHES ACROSS SERN VA...2+ INCHES PSBL ACROSS NERN NC. GENLY DRIER SAT AS THE FRONT WASHES OUT BUT WILL KEEP A 20-30% POP OVER THE FAR NW AND IN SE VA/NE NC. PARTLY SUNNY WITH HIGHS IN THE 80S. && .LONG TERM /THURSDAY THROUGH WEDNESDAY/... AMPLIFIED UPPER FLOW OVER THE HIGHER LATITUDES WILL PUSH ANOTHER ANOMALOUS TROUGH INTO THE NERN CONUS EARLY NEXT WEEK. THE RESULT WILL BE BELOW NORMAL TEMPS AND WET CONDITIONS FROM THE UPPER MIDWEST TO THE OH VALLEY. HOWEVER...THE LOCAL AREA REMAINS SEASONABLY WARM AS MUCH OF THE COOLER AIR WILL BE LOCKED WEST OF THE CNTRL APPALACHIANS. FOR THE LATTER HALF OF THE WEEKEND...ONGOING RETURN FLOW ON THE BACKSIDE OF HIGH PRESSURE ANCHORED OVER THE WRN ATLANTIC WILL RESULT IN SLIGHTLY WARMER TEMPS AND DEWPOINTS SUN COMPARED TO SAT. THICKNESSES YIELD TEMPS RIGHT AROUND 90 DEGS. A COLD FRONT WILL PUSH INTO THE GREAT LAKES REGION SUN WITH SFC TROUGHING DEVELOPING OVER THE LOCAL AREA. THETA-E ADVECTION AND A MOIST BL WILL RESULT IN MLCAPE VALUES ~1500 J/KG. MODEL DERIVED PRECIP WATERS RANGE FROM 1.75 TO 2 INCHES. WHILE MOISTURE/INSTABILITY LOOK FAVORABLE...BEST DYNAMICS/FORCING REMAINS WELL WEST OF THE AREA WITH THE BETTER HEIGHT FALLS AND STRONGER WINDS ALOFT. SHEAR IS ALSO UNIMPRESSIVE AND SOUNDINGS DEPICT SUBSIDENCE/WARM AIR ALOFT. WILL CARRY CHANCE POPS IN THE NW...TAPERING OFF TO SILENT IN THE SE. BETTER COVERAGE EXPECTED MON AS HEIGHT FALLS AND INCREASING WINDS ALOFT PROVIDE BETTER FORCING FOR ASCENT AND COOLER MID-LEVEL TEMPS. COLD FRONT IS EXPECTED TO REACH THE CNTRL APPALACHIANS LATE MON...SHARPENING THE THERMAL TROUGH OVER THE LOCAL AREA. WARMER TEMPS AND DEWPOINTS WILL PUSH MLCAPE VALUES HIGHER...BUT SHEAR REMAINS MARGINAL (AOB 20 KT). THE RESULT WILL BE SCT AFTERNOON SHOWERS/THUNDERSTORMS ACROSS MUCH OF THE REGION. COLD FRONT DROPS INTO THE REGION TUES-TUES NIGHT. EXACT TIMING OF THE FRONT WILL IMPACT SENSIBLE WEATHER OVER THE LOCAL AREA. WILL TREND TOWARD A BLEND BTWN THE MEDIUM RANGE GUIDANCE...KEEPING THE BEST POPS ALONG THE COAST TUES. BASED ON THE AIRMASS...WILL ALSO CARRY SLIGHT CHANCE POPS MON NIGHT-TUES MORNING AS THE FRONT CROSS THE REGION. UPPER LOW BEGINS TO EJECT FROM THE GREAT LAKES REGION TUES INTO SE CANADA...SLOWING THE FRONT AS IT PUSHES OFFSHORE TUES NIGHT-WEDS MORNING. CONFIDENCE IS NOT HIGH ATTM...BUT WILL HANG ON TO SLIGHT CHANCE POPS ALONG THE COAST WEDS BASED ON THE FRONT LIKELY STALLING OFFSHORE. TEMPS WILL REMAIN AROUND SEASONABLE NORMS...WARMING INTO THE UPPER 80S-LOW 90S THRU THE PERIOD. ANTICIPATE TUES TO BE THE WARMEST IN ADVANCE OF THE FRONT...WITH HIGHS GENERALLY IN THE LOW 90S. OVERNIGHT LOWS WILL GENERALLY BE IN THE UPPER 60S-LOW 70S...WITH MID 70S NEAR THE COAST. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... SCTD TSTMS CONTINUE ACROSS THE AREA AT 00Z. TSTMS WILL AFFECT KSBY AND KECG THROUGH 02-03Z...WITH SHWRS AND ISOLATED TSTMS AFFECTING KPHF/KORF THROUGH 06Z. HAVE KEPT TSTMS OUT OF KRIC...ALTHOUGH AN ISOLATED TSTM NOT OUT OF THE QUESTION. COLD FRONT TO THE NW WILL MAKE ITS WAY SLOWLY SEWD TONIGHT AND STALL ACROSS THE VA PIEDMONT. THIS WILL AGAIN SET THE STAGE FOR THUNDERSTORM DEVELOPMENT THURSDAY AFTERNOON THROUGH FRIDAY. MODELS HAVE NOT BEEN CONSISTENT WITH RESPECT TO THE BEST LOCATIONS. HWVR...BSSSED UPON LATST HI-RES GUIDANCE...HAVE ADDED SHWRS TO KPHF/KORF/KECG FROM 18Z ON TOMORROW...AND LEFT KRIC/KSBY BASICALLY DRY. FRONT CROSSES AREA BY FRIDAY...LEAVING FRI NGT/SAT DRY ATTM. NEXT FRONT COULD BRING THE POTENTIAL FOR MORE SHWRS/TSTMS TO THE REGION LATE SUNDAY OR MONDAY. && .MARINE... SUB-SCA CONDITIONS OVER THE WATERS THIS AFTERNOON WITH S-SW WINDS GENERALLY AROUND 10 KT...WAVES 1-2 FT AND SEAS 2 TO 3 FT. HIGHER WAVES OBSERVED IN THE NRN COASTAL WATERS...REACHING 4 FT 20 NM OUT. A FRONTAL BOUNDARY WILL DISSIPATE OVER THE WATERS THIS AFTERNOON/EVENING AS ANOTHER FRONT APPROACHES THE REGION TONIGHT...STALLING OVER THE REGION THURS. HIGH PRESSURE BUILDS INTO THE NE STATES THURS...REMAINING OVER NEW ENGLAND THRU FRI NIGHT. THE RESULT WILL BE NELY FLOW OVER THE WATERS THUR-FRI...REMAINING SUB SCA AT 10 KT OR LESS. HIGH PRESSURE PUSHES OFF THE NE COAST SAT INTO SUN...PHASING WITH SFC HIGH PRESSURE OVER THE WRN ATLANTIC. FLOW VEERS TO THE SOUTH SUN...REMAINING SUB SCA AT 10-15 KT. SEAS REMAIN 2-3 FT. LOW PRESSURE LIFTS INTO THE GREAT LAKES REGION MON AS A COLD FRONT PUSHES INTO THE OH VALLEY. GRADIENT WILL STRENGTHEN SLIGHTLY OVER THE WATERS SUN NIGHT-MON...BUT REMAINS SUB-SCA. PERSISTENT SLY FLOW WILL PUSH SEAS TO 4 FT IN THE NRN WATERS...BUT ANTICIPATE SEAS TO REMAIN UNDER 5 FT. COLD FRONT CROSSES THE WATERS TUES NIGHT-WED MORNING. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...LKB NEAR TERM...LKB/MAM SHORT TERM...LKB/MPR LONG TERM...SAM AVIATION...WRS MARINE...SAM

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