Area Forecast Discussion
Issued by NWS Wakefield, VA

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972 FXUS61 KAKQ 210214 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1014 PM EDT WED MAY 20 2015 .SYNOPSIS... A STALLED FRONTAL BOUNDARY REMAINS OVER THE CAROLINAS TONIGHT. LOW PRESSURE WILL TRACK EAST ALONG THE FRONT THURSDAY...THEN OFF THE COAST THURSDAY NIGHT. HIGH PRESSURE WILL BUILD ACROSS THE LOCAL AREA FRIDAY THROUGH THE WEEKEND. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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LATEST SFC ANALYSIS PLACES STATIONARY BOUNDARY OVER NC WITH LOW PRESSURE DEVELOPING OVER THE SE STATES. WHILE DEWPOINTS ARE GENERALLY IN THE 50S...DRY AIRMASS IS IN PLACE OVER THE REGION AS BLENDED TOTAL PRECIP WATERS ARE AROUND 0.60 INCHES. LATEST KWAL SOUNDING DEPICTS 0.42 INCHES WITH VERY DRY MID LEVELS. HOWEVER...A WARM/MOIST AIRMASS RESIDES JUST SOUTH OF THE BOUNDARY WITH PWATS AROUND 1.5 INCHES SRN NC. THIS AIRMASS WILL BEGIN TO LIFT NWD OVERNIGHT IN INCREASING SLY LOW LEVEL FLOW AS A SHORTWAVE VISIBLE ON GOES WATER VAPOR IMAGERY OVER WRN TN APPROACHES THE MID- ATLANTIC REGION. AREA OF PRECIP ASSOCIATED WITH THE WAVE OVERSPREADING MUCH OF THE TN/OH VALLEYS THIS EVENING. PRECIP ALONG WITH THICKENING CLOUDS WILL OVERSPREAD THE REGION THRU THE OVERNIGHT HOURS. BEST CHANCE FOR PRECIP WILL BE LATE TONIGHT INTO EARLY THURS MORNING ACROSS THE PIEDMONT INTO CNTRL VA AS MOISTURE...UVM AND ISENTROPIC LIFT COEXIST. INCREASED TIMING SLIGHTLY OVERNIGHT. ALSO NUDGED TEMPS UP SLIGHTLY ACROSS THE SOUTH AND SOUTHEAST AS CLOUDS AND MOISTURE INCREASES. LOWS GENERALLY IN THE MID-UPPER 50S INLAND TO LOW 60S ALONG THE COAST.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... THE AFORMENTIONED SFC LOW CONTINUES EASTWARD ALONG THE STALLED FRONT ON THU...REACHING EASTERN NC BETWEEN 18Z-21Z...THEN MOVING OFF THE COAST BY AROUND OR JUST AFTER 00Z FRI. S/W ENERGY APPROACHING FROM THE WEST WILL HELP DEEPEN/INTESIFY THE LOW SOMEWHAT AS IT PASSES THROUGH SE VA/NE NC LATER THURSDAY. THIS WILL MAKE FOR A TRICKY FORECAST WITH A COOL/WEDGE SCENARIO SETTING UP ACROSS MUCH OF VA AND LOWER MD. ALONG/SOUTH OF THE BOUNDARY...S-SE WINDS INCREASE AHEAD OF THE SFC LOW WHICH SHOULD BRING A SURGE OF WARM/UNSTABLE AIR INTO SE VA/NE NC IN THE AFTN/EVE. THE RESULT WILL BE QUITE A TEMP CONTRAST FROM NW TO SE...WITH HIGHS UPR 50S/NR 60 NW AND 75-80 DEG ACROSS NE NC. TEMPS ACROSS THE NW HALF OF THE FA SHOULD ACTUALLY HOLD STEADY THROUGH THE DAY (OR RISE ONLY A COUPLE OF DEGREES FROM DAYBREAK). ACROSS THE SE (WHERE WARMER/MORE UNSTABLE AIR WILL BE IN PLACE)... THERE WILL BE A POSSIBILITY OF TSTMS THU AFTN. SPC CURRENTLY HAS AREAS ALONG/SOUTH OF THE ALBEMARLE SOUND IN A SLIGHT RISK FOR SVR WX. DEPENDING ON THE EVENTUAL TRACK OF THE SFC LOW AND HOW MUCH SUN PEEKS THRU THE CLOUDS WILL DETERMINE WHETHER OR NOT A STRONGER STORM IS ABLE TO DEVELOP OVER NE NC. BASED ON GOOD MODEL CONSENSUS FOR THIS SYSTEM...DO HAVE WIDESPREAD LIKELY POPS (70%) ON THU ALL AREAS. TOTAL QPF AMOUNTS WILL BE ON THE ORDER OF 0.25-0.75". THE SFC LOW MOVES FARTHER OFFSHORE THU NIGHT RESULTING IN A GRADUAL DECREASE IN CLOUDS/POPS. LOW TEMPS FROM THE UPR 40S NW TO THE UPR 50S SE. SFC HIGH PRES TO THE WNW PREVAILS FOR MUCH OF FRIDAY ALLOWING FOR SUNSHINE AND COMFORTABLE TEMPS. HIGH IN THE MID/UPR 70S. HOWEVER...THE MODELS DO SHOW A SECONDARY COLD FRONT APPROACHING FROM THE NORTH LATE FRI...AND PASSING THROUGH THE AREA FRIDAY NIGHT. THERE MAY BE JUST ENOUGH MOISTURE PRESENT FOR AN ISOLD SHOWER ACROSS MAINLY THE NORTHERN NECK AND EASTERN SHORE...SO HAVE ADDED 20% POPS IN THE EVE TO ACCOUNT FOR THIS POTENTIAL. LOWS FROM THE UPR 40S NW TO NR 60 SE. BY SAT...COOL HIGH PRESSURE SETTLES OVER THE MID-ATLANTIC REGION. SUNSHINE IS EXPECTED WITH NORTH WINDS BECOMING ONSHORE LATE IN THE DAY HELPING TO KEEP MAX TEMPS IN CHECK. HIGHS 70-75...EXPECT 60S AT THE BEACHES. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... MEDIUM RANGE BEGINS WITH LATEST GFS/ECMWF REMAINING INTO GOOD AGREEMENT WITH UPPER LEVEL RIDGE CENTERED OVER FLORIDA ON SUN...BUILDING BACK NORTH INTO THE MID ATLC STATES MON/TUE. THE GFS TRIES TO FLATTEN/BREAK THE RIDGE DOWN LATE TUE INTO WED AS IT IS WEAKER WITH THE UPPER LEVEL TROUGH FROM THE DESRT SW TO THE SRN/CENTRAL PLAINS. ECMWF IS GENLY PREFERRED AT THIS TIME GIVEN THE BUILDING RIDGE OVER THE SE CONUS. THIS PATTERN WILL LEAD TO A WARMING TREND BEGINNING ON SUN...AS FLOW TURNS AROUND TO THE SSW WITH SFC HIGH PUSHING WELL OFFSHORE. A WEAK WARM FRONT STILL PROGGED TO LIFT N THROUGH THE OHIO VALLEY AND NRN MID ATLC REGION LATE SUN AFTN/SUN NIGHT...BUT BULK OF PRECIP SHOULD STAY OFF TO OUR N. WILL MAINTAIN A 20% POP ACRS THE FAR NE PORTIONS OF THE CWA TO ACCOUNT FOR THIS...BUT WILL MAINTAIN A DRY FORECAST ELSEWHERE UNDER PARTLY CLOUDY SKIES. HIGHS RISE INTO THE LWR 80S INLAND AND IN THE 70S CLOSER TO THE COAST. FROM MON-WED...500 MB HEIGHTS RISE AND BULK OF TSTM ACTIVITY SHOULD CONTINUE TO STAY OFF TO OUR NORTH. WILL KEEP A LATE AFTN/EVENING 20% POP OVER MAINLY THE NRN PORTIONS OF THE CWA ON MON...AND GENLY A 20% POP IN THE LATE AFTN/EVENING OVER MUCH OF THE AREA TUE/WED. IF GFS ENDS UP BEING CORRECT...POPS FOR WED WILL NEED TO BE RAISED. SUMMERLIKE WX RETURNS WITH INCREASING HUMIDITY AND HIGH TEMPS WARMING BACK TO 85-90 F MON...AND UPPER 80S TO LWR 90S TUE/WED. CONDITIONS WILL GENLY BE ABOUT 5 DEGREES COOLER AT THE COAST. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... WEAK HIGH PRESSURE OVER THE REGION WILL GRADUALLY GIVE WAY TO AN APPROACHING LOW PRES SYS OVERNIGHT. VFR CONDITIONS WILL CONTINUE THROUGH THE NIGHT BUT CLOUDS WILL INCREASE AS THE LOW PRES SYS APPROACHES. THE LOW WILL PRODUCE CLOUDS AND SHOWERS ACROSS THE REGION THURSDAY MORNING INTO THE AFTERNOON HOURS. EXPECT MVFR TO IFR CONDITIONS AS THE WAVE OF LOW PRESSURE SLIDES ACROSS NC AND BRIEFLY PULLS A WARM FRONT NORTH OF THE VA TIDEWATER AREA THURSDAY AFTERNOON. NORTH OF THE FRONT THE CLOUDS WILL BE LOWER...WITH PERIODS OF RAIN POSSIBLE. EXPECT CEILINGS IN THE 500 TO 2000 FT RANGE. SOUTH OF THE WARM FRONT...CEILINGS SHOULD LIFT SOME...1500 - 3500 FT...WITH THE CHANCES FOR THUNDERSTORMS POSSIBLE AFTER 18Z. THE LOW PRESSURE AREA WILL CLEAR THE COAST AFTER 00Z FRI AND WITH COOL HIGH PRESSURE BUILDING INTO THE AREA...RETURN THE REGION TO VFR CONDITIONS. ALTHOUGH...WITH THE LATE CLEARING OF THE MOISTURE THURSDAY EVENING...FOG MAY DEVELOP THURSDAY NIGHT INTO FRIDAY MORNING. WITH THE AREA OF HIGH PRESSURE IN PLACE THROUGH THE WEEKEND...VFR CONDITIONS ARE EXPECTED FOR THE HOLIDAY WEEKEND. && .MARINE... SIGNIFICANT CHANGES NEEDED TO THE NEXT 24-48 HRS GIVEN A STRONGER AND MORE NORTHERLY TRACK TO THE SFC LOW PRESSURE SYSTEM PASSING THROUGH NC ON THU...WITH RAPID INTENSIFICATION OFF THE COAST THU NIGHT. NAM/GFS DEPICT SFC PRESSURE RISES ON THE BACK SIDE OF THE SYSTEM TO BE ON THE ORDER OF 8MB/6HR THU NIGHT. THUS...WINDS HAVE BEEN RAMPED UP TO STRONG SCA CONDITIONS LATE THU/THU NIGHT/FRI MORNING...ESPECIALLY ACRS THE BAY. HAVE RAISED SCA HEADLINES FOR THE BAY AND THE LOWER JAMES BEGINNING LATE 2ND PERIOD (LATE THU AFTN). ELSEWHERE...SCA CONDITIONS PROBABLY HOLD OFF UNTIL 3RD PERIOD AND ENOUGH UNCERTAINTY EXISTS TO HOLD OFF UNTIL NEXT SHIFT BEFORE ISSUING HEADLINES...WHICH MOST LIKELY WILL BE NEEDED FOR ALL OR A PORTION OF THE OCEAN/THE SOUND AND POSSIBLY THE REMAINING PORTION OF THE RIVERS. CONDITIONS IMPROVE FRI AFTN...THEN WINDS SHOULD ONCE AGAIN INCREASE LATER FRI NIGHT/SAT MORNING WITH NEXT COOL SURGE AS COOL ~1030 MB HIGH PRESSURE BUILDS IN FROM THE N. THE POTENTIAL FOR ADDITIONAL HEADLINES BEING NEEDED EXISTS. AS THE HIGH SHIFTS OFF THE COAST SUN-THROUGH MON...THE FLOW TURNS BACK TO THE S/SE AND WILL AVG 10-15 KT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THURSDAY TO 10 AM EDT FRIDAY FOR ANZ630>632-634. SMALL CRAFT ADVISORY FROM 4 PM THURSDAY TO 7 AM EDT FRIDAY FOR ANZ638. && $$ SYNOPSIS...JDM NEAR TERM...JDM/SAM SHORT TERM...ALB/JDM LONG TERM...LKB AVIATION...ESS/JEF MARINE...LKB

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