Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 201955 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 355 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/... A FRONTAL BOUDARY WILL REMAIN STALLED ACROSS THE CAROLINAS THROUGH TONIGHT...WITH WEAK HIGH PRESSURE OVER THE LOCAL AREA. REMAINING DRY/COMFORTABLE THIS EVENING. ZONAL FLOW ALOFT WILL RESULT IN A QUICK RETURN OF MOISTURE FROM THE WEST AFTER MIDNIGHT. A SFC LOW WILL RIDE EASTWARD ALONG THE STALLED FRONT...REACHING WESTERN NORTH CAROLINA AROUND DAYBREAK...AS A SHORTWAVE IN ZONAL FLOW TRACKS EAST FROM THE MS/TN VALLEYS OVERNIGHT. CLOUDS ASSOCIATED WITH THIS SYSTEM WILL INCREASE AFTER MIDNIGHT...WITH A CHANCE OF SHOWERS REACHING THE I-95 CORRIDOR BY 12Z THU. LOW TEMPS TONIGHT MAINLY IN THE 50S. && .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 HIGH PRESSURE THEN GRADUALLY BUILDING SE FROM THE GREAT LAKES FRI NIGHT INTO SAT...AND SLIDING OFF THE MID ATLC AND CAROLINA COAST ON SUN. THIS WILL RESULT IN DRY CONDITIONS WITH FAIRLY COOL TEMPERATURES ON SAT...PARTICULARLY AT THE COAST ON AS THE STRENGTH OF THE HIGH IS FAIRLY IMPRESSIVE...1030 MB+ AND ONSHORE FLOW INCREASES IN THE AFTN AS A PIECE OF THE HIGH BECOMES CENTERED JUST OFFSHORE. EVEN WITH MOSTLY SUNNY SKIES HIGHS SAT WILL ONLY BE IN THE LWR-MID 70S INLAND TO THE MID 60S TO LWR 70S AT THE COAST. LOWS WILL GENLY RANGE THROUGH THE 50S BOTH SAT AND SUN MORNING (A FEW UPPER 40S POSSIBLE SAT MORNING OVER NW ZONES). FLOW TURNS AROUND TO THE SSW SUN/MON AS SFC HIGH PUSHES WELL OFFSHORE AND UPPER RIDGE AXIS MOVES BACK INTO THE REGION. SOME MODEL DISCREPANCIES BETWEEN THE GFS AND ECMWF...AND MODELS HAVE NOT BEEN REAL CONSISTENT WITH THEIR OWN RUNS. OVERALL TREND IS FOR SOME INCREASE IN MOISTURE AND A WEAK WARM FRONT TO LIFT N THROUGH THE OHIO VALLEY AND NRN MID ATLC REGION LATE SUN AFTN/SUN NIGHT. UPPER LEVEL RIDGE IS NOT REALLY ESTABLISHED YET SO HAVE INTRODUCED A 20% POP ACRS THE FAR NRN 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. ON MON/TUE...500 MB HEIGHTS RISE AND BULK OF TSTM ACTIVITY SHOULD STAY OFF TO OUR NORTH. WILL KEEP A LATE AFTN/EVENING 20-30% POP OVER MAINLY THE NRN AND WRN PORTIONS OF THE CWA. SUMMERLIKE WX RETURNS WITH INCREASING HUMIDITY AND HIGH TEMPS WARMING BACK TO 85-90 F MON...AND UPPER 80S TO LWR 90S TUE. CONDITIONS WILL GENLY BE ABOUT 5 DEGREES COOLER AT THE COAST. && .AVIATION /19Z WEDNESDAY THROUGH MONDAY/... WEAK HIGH PRESSURE IS SLIDING OVER THE AREA THIS AFTERNOON AND WITH DRY AIR IN PLACE...VFR CONDITIONS CONTINUE ACROSS THE REGION. THESE CONDITIONS SHOULD CONTINUE THROUGH THE EVENING HOURS INTO THE OVERNIGHT TIME PERIOD...BEFORE CLOUDS BEGIN TO INCREASE IN ADVANCE OF A WEAK LOW PRESSURE SYSTEM THAT IS MOVING TO THE EAST FROM THE LOWER MS VALLEY REGION THIS AFTERNOON. THIS 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...NONE. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...JDM LONG TERM...LKB AVIATION...ESS MARINE...LKB/TMG

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