Area Forecast Discussion
Issued by NWS Wakefield, VA

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KAKQ 200135 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 935 PM EDT TUE AUG 19 2014 .SYNOPSIS... LOW PRESSURE OFF THE VIRGINIA COAST WILL PULL AWAY FROM THE COAST TONIGHT...WHILE A WEAK FRONT SLOWLY SINKS SOUTH ACROSS SOUTHERN VA. THE FRONT RETURNS AS A WARM FRONT ON WEDNESDAY...AND REMAINS STALLED ACROSS THE AREA THROUGH THE COMING WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... HAVE LOWERED POPS FOR THE NEXT FEW HOURS TO JUST A SLIGHT CHANCE OF A BRIEF PASSING SHOWERS MAINLY IN THE SOUTHEAST WITH THE FLOW OFF THE WATER AND IN THE WEST AS A FEW SHOWERS DROP SOUTHEAST OF THE MOUNTAINS. ANY SHOWER ACTIVITY OVER THE NEXT FEW HOURS AND OVERNIGHT WILL BE ISOLATED. HAVE ALSO ADDED A MENTION OF SOME PATCHY FOG ACROSS THE SOUTH AND WEST FOR A BRIEF PERIOD FROM 07Z- 10Z. FOG SHOULD NOT BECOME DENSE AND WIDESPREAD VSBYS WILL LIKELY NOT DROP LOWER THAN 2 MILES THOUGH A FEW PATCHY SPOTS COULD DROP TO 1 MILES OR LESS ESPECIALLY IN AREAS WHICH HAVE RECEIVED A LOT OF RAIN OVER THE LAST 36 HOURS. THE SLOW MOVING LOW PRESSURE SYSTEM OFF THE VA CAPES CONTINUES TO SLOWLY PULL AWAY FROM THE COAST AND WINDS HAVE INCREASED ALONG THE COAST WITH THE ONSHORE FLOW. BASED ON RADAR TRENDS AND WIND FIELDS THE WEAK FRONT HAS DROPPED SOUTH INTO NORTHEAST NC THEN EXTENDS NW TO NEAR LAKE GASTON. TEMPERATURES ARE EXPECTED TO DROP A FEW MORE DEGREES THAN LAST NIGHT WITH READINGS IN THE MID TO UPPER 60S IN NRN PORTIONS OF THE CWA AND LOW 70S SOUTH. ON WEDNESDAY...THE UPPER LOW OVER THE GREAT LAKES BEGINS TO DIG INTO THE MID ATLANTIC STATES WITH A COLD FRONT PUSHING INTO THE OHIO VALLEY. THIS WILL FORCE THE FRONT SOUTH OF THE AREA TO LIFT BACK NORTH AS A WARM FRONT. WITH SOME DAYTIME HEATING AND THE RESIDUAL LOW LEVEL MOISTURE STILL AROUND...SHOULD SEE SOME AFTERNOON TO EVENING CONVECTION FORM IN THE PIEDMONT AND THEN HEAD EASTWARD WITH THE WARM FRONT. THE 12Z NAM IS MORE EXCITED AND MUCH MORE LIFT THAN THE GFS OR ECMWF. THE MODELS TEND TO AGREE ON AREAS ACROSS NORTHERN VA FOR RAIN BUT NOT AS MUCH FURTHER SOUTH SO HAVE TAPERED POPS A BIT LOWER IN THE SOUTH. FOR TEMPERATURES HAVE LEANED TOWARD THE MET NUMBERS AS THE MAV HAVE BEEN TOO WARM...BUT SHOULD SEE MID TO UPPER 80S WITH MORE SUNSHINE. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... THE OVERALL PATTERN IS AGREED UPON IN THE MID RANGE PART OF THE FORECAST AS THE UPPER LOW OVER THE GREAT LAKES SLIDES INTO THE EAST AND THE UPPER RIDGE OVER THE MS VALLEY BUILDS NORTHWARD...SETTING UP NW OVER OF THE MID ATLANTIC REGION. HOWEVER...BEYOND THE THAT...THE TIMING OF INDIVIDUAL WAVES AND THE POTENTIAL FOR CONVECTIVE COMPLEXES MAKES THE TIMING OF PRECIPITATION VERY UNCERTAIN FOR THURSDAY AND FRIDAY. AT THE SURFACE...THE FRONTAL BOUNDARY THAT WILL BE IN THE VICINITY SHOULD BE SOME STATIONARY AND PARALLEL TO THE FLOW ALOFT AND COULD ALSO BE A FOCUS FOR CONVECTION. AT THIS POINT...WITH THE UNCERTAINTY...LEANED MORE TOWARD CLIMATOLOGY WITH BEST CHANCES IN THE PIEDMONT EARLY IN THE AFTERNOON AND THEN AREA WIDE IN LATE AFTERNOON THROUGH ABOUT MIDNIGHT. SUCCEEDING MODEL RUNS WILL HOPEFULLY IMPROVE THE CONFIDENCE IN THE TIMING OF THE INDIVIDUAL WAVES AND COMPLEXES. FOR TEMPERATURES...CONTINUED A SLOW WARMING TREND FOR THURSDAY AND FRIDAY...BUT DID NOT GO AS WARM AS THE MAV NUMBERS...LEANING TOWARD THE MET NUMBERS WHICH LEANED TOWARD THE UPPER 80S TO LOW 90S ON THURSDAY AND SLIGHTLY COOLER ON FRIDAY WITH MORE CLOUDS POSSIBLE. FOR LOWS HAVE LEANED WARM THAN GUIDANCE THINKING MORE CLOUDS AROUND AND A MORE HUMID AIR MASS LIMITING THE COOLING. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... UNSETTLED WEATHER PATTERN CONTINUES INTO THE EXTENDED PERIOD IN NWLY FLOW ALOFT...BUT DRIER CONDITIONS EXPECTED BY EARLY NEXT WEEK. TEMPS WILL BE SLIGHTLY BELOW SEASONABLE...LATE SUMMER NORMS TO BEGIN THE EXTENDED BEFORE RETURNING TO NEAR NORMAL EARLY NEXT WEEK. UPPER LEVEL FLOW DURING THE EXTENDED IS HIGHLIGHTED BY SPLIT/BLOCKY FLOW OFF THE ERN CANADA AND NERN US COAST AND AMPLIFYING HIGH PRESSURE OVER THE SRN CONUS. THIS PLACES THE MID-ATLANTIC REGION IN NWLY FLOW ALOFT. ASSOCIATED BACK DOOR FRONT WILL PUSH SOUTH OF THE LOCAL AREA SATURDAY MORNING. SFC HIGH PRESSURE PROGGED OVER THE NE WILL RIDGE SWWD ALONG THE COAST AND INTO CNTRL VA. NLY LOW-LEVEL FLOW INDICATED IN MEDIUM RANGE GUIDANCE WILL DRIVE DEWPOINTS DOWNWARD INTO THE MID 60S. HOWEVER...MODEL DERIVED PWATS REMAIN AROUND 1.8 TO 2.0 INCHES. COMBINED WITH PERTURBATIONS IN THE NWLY FLOW...WILL MAINTAIN CHANCE POPS FOR DIURNALLY DRIVEN SHOWERS/THUNDERSTORMS. WILL ALSO NEED TO WATCH FOR POSSIBLE MCS DEVELOPMENT UPSTREAM...ROUNDING THE RIDGE AND DROPPING INTO THE REGION OVERNIGHT THRU THE WEEKEND. BY EARLY NEXT WEEK THE RIDGE AXIS WILL BEGIN TO BUILD INTO THE REGION AS SFC HIGH PRESSURE IS PROGGED TO LOCATE OFF THE COAST. BLOCK WILL REMAIN OFF THE NE COAST...BUT MOISTURE FEED WILL BE CUT OFF. DECREASING MOISTURE AND INCREASING SUBSIDENCE WILL LIKELY RESULT IN DRY CONDITIONS. HOWEVER...CONFIDENCE IS NOT HIGH ATTM...SO WILL LEAVE POPS SILENT. NORTH OF THE BOUNDARY...THICKNESSES AND GUIDANCE YIELD TEMPS IN THE LOW TO MID 80S THRU MONDAY (AROUND -1 STD DEV). OVERNIGHT LOWS GENERALLY IN THE UPPER 60S TO LOW 70S NEAR THE WATER. WARMING BACK UP TO NEAR SEASONABLE NORMS TOWARD THE MIDDLE OF NEXT WEEK. && .AVIATION /02Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE BRIEFLY BUILDS OVER THE AREA FROM THE NORTH BEHIND DEPARTING LOW PRESSURE SYSTEM. UPPER LEVEL SHORT WAVES IN A W/NW FLOW WILL KEEP CONDITIONS UNSETTLED FOR THE NEXT SEVERAL DAYS. MOIST GROUND AND LOW LEVEL CONDITIONS WILL MAINTAIN THE CHC FOR ISSUES WITH CIG/VSBY EACH MORNING. AS OF 00Z...NE WINDS PREVAILED AT THE TAF SITES WITH NO PCPN EXPECTED OVERNIGHT. SKY CONDITIONS WILL BE VARIABLE WITH GRADUAL LOWERING OF CIGS AND VSBYS. THE MAIN LIMITATION IS INDICATED TO BE CIGS BUT VSBYS ARE NOT OFF THE TABLE. USED THE RESULTS OF THE PREVIOUS OVERNIGHT AS A PARTIAL GUIDE AND A MIX OF MOS GUIDANCE TO MAKE A PLAN FOR THE CURRENT TAF. DESPITE ECG HAVING THE CLOSEST T/TD SPREAD...EXPERIENCE FROM THIS MORNING WOULD INDICATE THEY WILL NOT GO DOWN TO IFR FOR A WHILE (I.E. AROUND 12Z) AND MAY HAVE NO LOWER THAN MVFR. HAVE RIC/PHF WITH SOME PERIODS OF IFR. SBY MOS IS BIASED BY TEMPERATURES THAT ARE TOO LOW. KEPT ORF OUT OF IFR DUE TO CLIMATOLOGY. CONDITIONS SHOULD BE VFR BY AROUND 14-15Z. ON WEDNESDAY...THERE WILL BE A CHC FOR LATE AFTN/EVENING TSTMS...ESPECIALLY NORTH PORTIONS. WINDS VEER TOWARD E/SE. OUTLOOK...CHC FOR AFTN TSTMS THURSDAY THROUGH SATURDAY. SOME MVFR/IFR PSBL NEAR SUNRISE EACH MORNING. CURRENT FORECAST IS DRY ON SUNDAY. && .MARINE... SUB-SCA CONDITIONS PREVAIL THRU THE FORECAST PERIOD. LOW PRESSURE HAS JUST LOCATED OFF THE VA CAPES THIS AFTERNOON WITH A FRONTAL BOUNDARY EXTENDING WWD OVER SRN VA. GENERALLY ONSHORE FLOW 10-15 KT OVER THE WATERS...NORTH OF THE LOW. SEAS HAVE ALSO BUILT TO 3-4 FT IN THE NRN WATERS. WAVES GENERALLY 1-2 FT. LOW PRESSURE PUSHES SLOWLY OFFSHORE TONIGHT AS WEAK HIGH PRESSURE RIDGES OVER THE NRN WATERS. LOW PRESSURE REMAINS JUST OFFSHORE THRU THE END OF THE WEEK AS A WEAK BOUNDARY REMAINS OVER THE WATERS. HIGH PRESSURE BUILDS OVER NEW ENGLAND...RIDGING SWD OVER THE LOCAL AREA. THE RESULT WILL BE PERSISTENT ONSHORE FLOW...AVG AROUND 10 KT. SEAS REMAIN 2-3 FT. BY THE WEEKEND...THE GRADIENT TIGHTENS WITH NELY WINDS INCREASING TO 10-15 KT. WILL PUSH SEAS IN THE NRN WATERS TO 3-4 FT...WITH 5 FT POSSIBLE 20NM OUT. FRONT PUSHES SOUTH OF THE WATERS SAT AS HIGH PRESSURE BUILDS BACK OVER THE WATERS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...ESS NEAR TERM...ESS/JAO SHORT TERM...ESS LONG TERM...SAM AVIATION...LSA MARINE...SAM

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.