Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 270808 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 408 AM EDT WED MAY 27 2015 .SYNOPSIS... HIGH PRESSURE REMAINS ANCHORED WELL OFF THE MID ATLANTIC COAST TODAY AND THURSDAY...WITH A TROUGH OF LOW PRESSURE NEARLY STATIONARY EAST OF THE MOUNTAINS. HIGH PRESSURE WILL BUILD OVER THE NORTHEAST STATES ON FRIDAY...AND SLIDE OFF THE COAST ON SATURDAY. A SLOW MOVING COLD FRONT WILL APPROACH THE LOCAL AREA LATER IN THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... CURRENT ANALYSIS INDICATES SFC LOW PRESSURE OVER THE UPPER PENINSULA OF MICHIGAN...WITH HIGH PRESSURE WELL OFF THE MID ATLC COAST. FLOW ALOFT IS FROM THE SW TO SSW ON THE PERIPHERY OF UPPER RIDGE CENTERED OFF THE SE COAST. LOCAL AREA REMAINS PRECIP-FREE BUT CLOUDS HAVE INCREASED OVER MUCH OF THE INTERIOR. TEMPS ARE VERY WARM...GENLY BETWEEN 70 AND 75 F WITH DEW PTS PRIMARILY IN THE MID TO UPPER 60S. FOR TODAY...EXPECTING INCREASED CHANCES FOR PRECIP COMPARED TO THE PAST SEVERAL DAYS OF DRY WX. THIS DUE TO UPPER RIDGE WEAKENING AND A MORE PRONOUNCED SFC/LEE TROUGH OVER THE PIEDMONT. MODELS SHOW VARYING SOLUTIONS WITH RESPECT TO PRECIP COVERAGE AND LOCATION LATER TODAY. WILL GENLY FAVOR THE LATE AFTN/EVENING TIMEFRAME AS MODEL DEPICTION OF MORNING PRECIP HAS BEEN OVERDONE THUS FAR. MOST OF THE CWA WILL BE IN A MARGINAL RISK FOR SEVERE WX...OVERALL SHEAR IS TOO WEAK (HIGHER N/NE OF THE LOCAL AREA) TO SUPPORT MORE WIDESPREAD SEVERE WX. THE SFC/LEE TROUGH MAY ACT AS A FOCUSING MECHANISM WITH FAIRLY HIGH CAPE VALUES BY AFTN. WILL GENLY KEEP COVERAGE OF TSTMS IN THE 30-40% RANGE...A LITTLE LOWER TOWARDS THE SE VA/NE NC COAST. PWAT VALUES REMAIN HIGH ~1.75" AND EVEN THOUGH H7 TO H5 FLOW IS AROUND 20 KT...A LOW LEVEL JET IS FORM NEAR THE SAME DIRECTION AND SPEED SO TRAINING CELLS AND LOCALLY HEAVY RAIN/MINOR FLOODING WILL BE POSSIBLE IF STORMS GET INITIATED. WARM AGAIN WITH HIGHS GENLY IN THE MID TO UPPER 80S...LOCALLY IN THE 70S AT THE IMMEDIATE COAST. && .SHORT TERM /THURSDAY THROUGH FRIDAY/... MODELS CONTINUE TO SHOW A PERSISTENT TROUGH ON THU WHICH WHEN COMBINED WITH THE APPRCHG MSTR FROM THE WSW WILL LIKELY BE THE TRIGGER FOR MORE SCT CONVECTION THU AFTN/EARLY EVENING. TIMING RATHER PROBLEMATIC GIVEN LOW CONFIDENCE OF S/W ENERGY EJECTING NE FROM DSPTG MCS`S....BUT THE EMPHASIS OF THIS FCST WILL BE FOR MAINLY DIURNALLY DRIVEN CONVECTION EACH DAY. HIGHEST POPS (40-50%) WILL BE ACROSS THE NWRN THIRD OF FA...20-30% REST OF FA. THREAT WILL BE FOR LCLLY HVY DOWNPOURS GIVEN THE PW`S AOA 1.5 INCHES...DP TMPS IN THE 60S AND RELATIVELY WEAK STEERING CURRENTS. HIGHS EACH DAY IN THE 80S...XCPT 70S AT THE IMMEDIATE COAST AGAIN. POPS ON FRI SHOULD BEGIN TO DIMINISH A BIT AND FOCUS MORE WEST OF I-95 AS SFC HIGH PUSHES OFF THE NE COAST AS SLIDES SOUTH INTO THE MID ATLC. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... LONG TERM PERIOD STARTS OFF SAT WITH AN UPR-LEVEL RIDGE BREAKING DOWN OVER THE ERN SEABOARD AS A COLD FRNT DROPS INTO THE MED ATLC REGION. THERE IS STILL SOME DIFFERENCES AMONGST MODELS IN REGARDS TO WHEN THE FRNT MAKES IT INTO THE LOCAL AREA WHICH WOULD AFFECT TIMING OF PCPN...WITH THE 12Z GFS FASTER THAN THE 12Z ECWMF. FOR NOW WITH THIS STILL SEVERAL DAYS OUT WILL FORECAST 20-30% POPS SAT INCREASING TO 30-50% SUN WITH THE FRNT IN THE VICINITY. EXPECT ABOVE NORMAL TEMPS BOTH DAYS WITH HIGHS AVGG IN THE MID TO UPR 80S. CHANCE OF RAIN CONTINUES INTO ERLY NEXT WEEK WITH TEMPS NOT QUITE AS WARM AS THE WEEKEND...HIGHS ONLY IN THE UPR 70S TO LWR 80S ON AVG. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/... HIGH PRESSURE HAS CENTERED OFF THE MID-ATLANTIC COAST EARLY THIS MORNING...AS LOW PRESSURE LOCATES OVER THE GREAT LAKES REGION. THE RESULT IS A S-SW WIND 5-15 KT...STRONGEST NEAR THE COAST. LATEST SATELLITE INDICATES BKN-OVC MVFR DECK (1500-2000 FT AGL) EXPANDING ACROSS SOUTH CENTRAL VA. MVFR CONDITIONS HAVE SPREAD NWD INTO KRIC. ABUNDANT LOW-LEVEL MOISTURE IN TANDEM WITH AN UPPER LEVEL DISTURBANCE WILL RESULT IN THE CONTINUED EXPANSION OF THIS CLOUD DECK...BUT DUE TO SUB-CLOUD LAYER MIXING...DO NOT ANTICIPATE IFR CIGS LIKE SOME GUIDANCE INDICATES. COMBINATION OF CLOUD COVER...MIXING AND RELATIVELY DRY SOILS WILL INHIBIT FOG DEVELOPMENT THIS MORNING. FOR TODAY...EXPECT MVFR DECK TO ERODE BY MID-MORNING AS HIGH PRESSURE REMAINS OVER THE REGION. S-SW WINDS OF 10-15 KT PERSIST TODAY WITH OCCASIONAL GUSTS AROUND 20 KT. ISOLATED-WIDELY SCATTERED SHOWERS/THUNDERSTORMS POSSIBLE AFTER 18Z...MAINLY OVER THE PIEDMONT INTO CENTRAL VA. HIGH PRESSURE DOMINATES INTO THE WEEKEND...RESULTING IN DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS. VFR CONDITIONS WILL PREVAIL OUTSIDE OF THUNDERSTORMS. && .MARINE... LATEST OBS OVER THE WATER INDICATE SUBSIDING S-SW WINDS OVER THE WATER...DROPPING AOB 15 KT. WAVES AVG 2 FT AND SEAS 2-4 FT. HIGH PRESSURE REMAINS OFFSHORE TODAY AS LOW PRESSURE LIFTS INTO SE CANADA. A TRAILING COLD FRONT EXTENDS SWWD OVER THE GREAT LAKES REGION. HI-RES GUIDANCE INDICATES ANOTHER EVENING OF SCA CONDITIONS THIS EVENING...BUT GRADIENT WINDS ARE WEAKER THAN LAST NIGHTS (TUES NIGHT) MARGINAL SCA CONDITIONS. TEMP ADVECTION IS ALSO NEUTRAL. HAVE CAPPED WIND SPEEDS AT 15 KT AS A RESULT...REMAINING SUB-SCA. AFOREMENTIONED COLD FRONT REMAINS WELL NORTH OF THE REGION THURS AS THE HIGH PUSHES FARTHER OFFSHORE. SLY WINDS AVG 10-15 KT. HIGH PRESSURE BUILDS OVER THE NE STATES AND SE CANADA THURS-FRI BEHIND THE FRONT...RELAXING THE GRADIENT OVER THE LOCAL WATERS. FLOW BECOMES SELY THURS NIGHT-FRI...AOB 10 KT. HIGH PRESSURE AND SLY WINDS AOB 15 KT PERSIST OVER THE WATER INTO THE WEEKEND. A COLD FRONT APPROACHES FROM THE WEST SUNDAY...REACHING THE WATERS SUN NIGHT BEFORE STALLING. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...NONE. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...LKB/MPR LONG TERM...MAS AVIATION...SAM MARINE...SAM

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