Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 191944 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 344 PM EDT SUN APR 19 2015 .SYNOPSIS... LOW PRESSURE TRACKING NORTH FROM THE MISSISSIPPI VALLEY INTO THE GREAT LAKES REGION TONIGHT...PUSHING A WARM FRONT THROUGH THE LOCAL AREA. A COLD FRONT THEN CROSSES THE AREA MONDAY NIGHT. HIGH PRESSURE BUILDS BACK IN FROM THE SOUTHWEST ON TUESDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... CLDNS HAS SPREAD ACRS MOST OF THE FA AS OF MID AFTN...W/ RA MAKING STEADY PROGRESS INTO CNTRL/SRN PORTIONS. SYNOPTIC PATTERN SETTING UP FOR A WIDESPREAD SIGNIFICANT RAINFALL OVR THE FA. W/ HI PRES OFF OF NEW ENG...AND LO PRES W OF THE MTNS...A SIGNFICANT INFLO OF DP LYRD MOISTURE XPCD OVRNGT AS A WARM FRONT PROGRESSES NE THROUGH THE FA. HAVE CONTD MENTION OF HVY RA...AND MDLS DO HINT AT MINIMAL INSTABILITY PUSHING NWD INVOF ERN PORTIONS OF VA AND OVR NE NC LT THIS EVE/AFT MDNGT SO ADDED SLGT CHC-CHC THUNDER. QPF AVGG 0.75-1.50"...MAYBE LOCALLY HIGHER AMTS. PCPN AMTS TO RMN BLO 6-12 HR FLASH FLOOD GUIDANCE SO NO FLASH FLOOD WATCH WILL BE ISSUED. MAJORITY OF THE RA SHIFTS TO THE CST BY 12Z/20. THERE WILL ALSO BE GUSTY ESE WNDS TO 20-30 MPH...HIGHEST NR THE CST. ADDED AREAS OF FG (VSBYS 1-3NM) OVR THE WTRS - AFT MDNGT...DUE TO WARMER AIR SPREADING OVR COOLER WTRS. LO TEMPS TNGT FM THE M50S TO M60S. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... THE AREA OF RAIN WILL SHIFT OFF THE COAST MON MRNG...THEN CONCERN SHIFTS TO A TROUGH ALOFT APPROACHING FROM THE WEST BY LATE MON AFTN/EVE (LIKELY LEADING TO SCT SHWRS/TSTMS). SPC CONTS TO PUT THE AREA OUTLOOKED IN A SLIGHT RISK OF SVR TSTMS MON AFTN/EVE FOR THE POTENTIAL OF ISOLD DAMAGING WIND GUSTS AND LARGE HAIL. THE POTENTIAL FOR SVR WX IS CERTAINLY THERE GIVEN ML CAPE VALUES EXPECTED TO BE IN THE 1000-1500 J/KG RANGE...STEEP LAPSE RATES...AND A MODEST SHEAR PROFILE. WILL CONT TO HIGHLIGHT POSSIBLE STRONG/ISOLD SVR STORMS IN THE HWO FOR LATE MON AFTN/EVE. OTW...VRB CLOUDS-PARTLY SUNNY AND BREEZY/WARMER MIDDAY/AFTN ON MON. HI TEMPS IN THE 70S AT THE CST...80 TO 85 ELSW. COLD FRONT CROSSES THE FA MON NGT WITH CHC POPS...THEN DRYING/COOLER WESTERLY FLOW TAKING OVR INTO TUE. PARTLY/MOSTLY SUNNY TUE WITH HI TEMPS IN THE UPR 60S TO NR 70 AT THE COAST...AND L/M70S ELSW. HI PRES MOVES TO NR THE SE CONUS CST BY WED...PROVIDING WSW FLO AND CONTG MILD WX. A WK TROUGH SFC-ALOFT WILL BE APPROACHING FM THE WNW...WHICH MAY RESULT IN INCRSG CLDNS W AND N...ALG W/ PSBL ISOLD/SCT SHRAS/TSTMS (HWVR WILL CAP POPS AT 14% THOSE AREAS FOR NOW). LO TEMPS TUE NGT M40S W AND N TO FAR L50S SE. HI TEMPS WED IN THE L/M70S N AND NW...TO M/U70S CNTRL/SE. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... BROAD CYCLONIC FLOW PREVAILS THRU THE EXTENDED PERIOD AS UPPER CLOSED LOW REMAINS IN VIC OF THE GREAT LAKES AND NEW ENGLAND. TO BEGIN THE PERIOD...FAST MOVING COLD FRONT CROSSES THE REGION LATE WEDS NIGHT-EARLY THURS MORNING. GFS CONTINUES TO REMAIN ON THE SLOWER SIDE OF MODEL GUIDANCE WRT FRONTAL PASSAGE...WITH THE ECMWF QUICKER. BASED ON WLY FLOW ALOFT AND HIGH PRESSURE BACK OVER THE MIDWEST...OPTED TO REINTRODUCE SLIGHT CHANCE POPS WEDS NIGHT OVER THE NRN AND NERN ZONES AND THEN THURS SOUTH AND EAST OF RICHMOND...TRENDING SLIGHTLY TOWARD THE SLOWER GFS. HIGHS THURS AROUND NORMAL...LOW-MID 60S. THEREAFTER...COOL HIGH PRESSURE BUILDS SWD FROM THE CANADIAN PRAIRIES INTO THE MIDWEST...EXTENDING INTO THE MID-ATLANTIC REGION FRI. HIGHS FRI GENERALLY IN THE UPPER 50S NE TO MID 60S SE UNDER A PARTLY CLOUDY SKY AND NWLY WINDS. SRN STREAM SHORTWAVE PROGGED TO LIFT INTO THE MIDWEST FRI NIGHT-SAT WITH ASSOCIATED SFC LOW FORECAST TO PROGRESS EWD ALONG A STATIONARY BOUNDARY OVER THE GULF STATES SAT. MOISTURE RETURNS SAT TO GO ALONG WITH OVERRUNNING AND WEAK PERTURBATIONS ALOFT. INCREASED POPS TO SLIGHT CHANCE N TO CHANCE S. HIGHS SAT GENERALLY AROUND 60 ACROSS THE REGION. SFC LOW MOVES OFF THE CAROLINA COAST SAT NIGHT...WITH ANY REMAINING PRECIP EXPECTED ACROSS THE SE LOCAL AREA. HIGH PRESSURE RETURNS SUN...BUT COOL CONDITIONS PERSIST WITH HIGHS IN THE UPPER 50S NE TO LOW 60S SE. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... A BACKDOOR COLD FRONT HAS DROPPED SOUTH INTO THE CAROLINAS RESULTING IN ENE WINDS OF 10 TO 15 KT BEHIND THE FRONT. WINDS NEAR THE COAST WILL INCREASE TO 15-20KT THROUGH LATE AFTERNOON AND EARLY EVENING. THE FRONT WILL LIFT BACK NORTH AS A WARM FRONT LATER THIS EVENING AND TONIGHT AHEAD OF A COMPLEX LOW PRESSURE SYSTEM OVER THE OHIO RIVER VALLEY. THIS WILL RESULT IN MVFR AND IFR CONDITIONS SPREADING RAPIDLY NORTHEAST ACROSS THE ENTIRE AREA LATER THIS AFTERNOON AND THROUGH THE EVENING/OVERNIGHT HOURS. IFR CEILINGS AND OCCASIONAL HEAVY RAIN ARE EXPECTED THIS EVENING AND ESPECIALLY OVERNIGHT AT ALL TAF SITES. EXPECT SEVERAL HOURS OF IFR CONDITIONS TO PERSIST ACROSS THE REGION FROM AROUND 00-03Z THROUGH AT LEAST 12-15Z. WIDESPREAD RAIN WHICH IS ALREADY MOVING INTO SOUTH CENTRAL VA WILL SPREAD NORTHEAST AND WILL NOT DIMINISH FROM SW- NE UNTIL 09Z TO 12Z MONDAY. ANOTHER IMPULSE TRACKS ACROSS THE REGION MONDAY AFTERNOON/EVENING BRINGING A CHC OF SHRA/TSRA. THERE IS A SLIGHT RISK OF SEVERE STORMS MONDAY AFTERNOON/EVENING WITH THE MAIN THREAT BEING STRONG TO DAMAGING WIND GUSTS. HIGH PRESSURE BUILDS ACROSS THE SOUTHEAST STATES TUESDAY AND WEDNESDAY AS LOW PRESSURE LINGERS OVER THE GREAT LAKES. THIS WILL ALLOW DRY CONDITIONS TO RETURN. A WEAK COLD FRONT DROPS ACROSS THE REGION THURSDAY. && .MARINE... LATEST WX ANALYSIS DEPICTS LOW PRESSURE OVER THE MID MS VALLEY...HIGH PRESSURE OFF THE NE COAST AND A BACKDOOR COLD FRONT LOCATED NEAR THE VA/NC BORDER. GRADIENT HAS RESULTED IN INCREASING ELY WINDS OVER THE WATER THIS AFTERNOON...WITH SCA HEADLINES NOW IN EFFECT FOR ALL WATERS. SPEEDS GENERALLY 15 TO 25 KT. SEAS HAVE BUILT TO 6 FT IN THE NRN WATERS AND 3-4 FT ELSEWHERE. WAVES GENERALLY 2-3 FT. LOW PRESSURE LIFTS INTO THE GREAT LAKES REGION TONIGHT...WITH SECONDARY LOW PRESSURE DEVELOPING OVER THE MID-ATLANTIC REGION. THIS IS A FAVORABLE PATTERN FOR A SHORT DURATION (~3-5 HR) OF STRONG SCA CONDITIONS IN SE FLOW. HI-RES GUIDANCE CONTINUES TO HIGHLIGHT THE MIDNIGHT TO 4-5AM TIMEFRAME FOR THE STRONGEST SE WINDS OF 20-25 KT WITH GUSTS OF 30 KT. BUMPED UP SEAS TO 6-9 FT (HIGHEST IN THE NRN COASTAL WATERS) LATE TONIGHT. FOG ALSO EXPECTED OVER THE WATERS TONIGHT AS WAA OCCURS OVER COOL WATER. GRADIENT WINDS DIMINISH MON MORNING AS FLOW BECOMES SLY 10-15 KT. FAVORABLE FETCH/SWELL WILL KEEP SEAS ELEVATED THRU THE DAY...BUT SUBSIDING TO 4 TO 6 FT. COLD FRONT APPROACHES FROM THE WEST LATE MON...CROSSING THE REGION TUES NIGHT. SLIGHT UPTICK IN SLY WINDS EXPECTED MON EVENING IN ADVANCE OF THE FRONT...AROUND 15 KT IN THE BAY AND 20 KT COASTAL WATERS. SHOWERS/THUNDERSTORMS EXPECTED ALONG THE FRONT...WITH STRONG GUSTY WINDS POSSIBLE. SEAS SUBSIDE LAST MON NIGHT-TUES MORNING THANKS TO WLY WINDS. SCA CONDITIONS NOT EXPECTED BEHIND THE FRONT. HEADLINES HAVE BEEN EXTENDED THRU 7AM TUES FOR COASTAL WATERS SOUTH OF PARRAMORE ISLAND AND THRU 1PM TUES NORTH OF PARRAMORE ISLAND. HIGH PRESSURE BUILDS ACROSS THE SOUTHEAST TUESDAY AND WEDNESDAY AS LOW PRESSURE LINGERS OVER THE GREAT LAKES. A WEAK COLD FRONT CROSSES THE REGION LATE WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE RETURNS INTO THE WEEKEND. && .HYDROLOGY... AVG QPF 0.75-1.50" TNGT OVR MOST OF THE RIVER BASINS WILL RESULT IN RIVER LVLS TO PSBLY RISE TO 1/2-NR FULL BANKFULL TUE INTO WED. && .TIDES/COASTAL FLOODING... A PERIOD OF ONSHORE FLOW TODAY FOLLOWED BY MODEST SE FLOW TONIGHT WILL ALLOW TIDAL ANOMALIES TO BUILD TO ~1.0FT ABOVE NORMAL LATER TONIGHT PRIMARILY IN THE MIDDLE BAY AND ALONG THE ATLANTIC COAST OF THE MD ERN SHORE. SOUTHERLY FLOW MONDAY INTO MONDAY EVENING WILL HELP MAINTAIN ~1.0FT ANOMALIES IN THE MIDDLE BAY THROUGH MONDAY NIGHT. TIDAL ANOMALIES WILL BEGIN TO SUBSIDE TUESDAY AS THE FLOW SHIFTS TO OFFSHORE. THE COMBINATION OF TIDAL ANOMALIES AND HIGH ASTRO TIDES (NEW MOON PHASE) WILL PUSH MOST SITES OVER HAT DURING HIGH TIDE SUNDAY NIGHT AND MONDAY. PORTIONS OF THE MIDDLE BAY AND OCEAN CITY WILL APPROACH MINOR FLOODING THRESHOLDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 AM EDT MONDAY FOR ANZ630>638. SMALL CRAFT ADVISORY UNTIL 7 AM EDT TUESDAY FOR ANZ654-656-658. SMALL CRAFT ADVISORY UNTIL 1 PM EDT TUESDAY FOR ANZ650-652. && $$ SYNOPSIS...ALB/JDM NEAR TERM...ALB/JDM SHORT TERM...ALB/JDM LONG TERM...SAM AVIATION...AJZ/JAO MARINE...SAM HYDROLOGY... TIDES/COASTAL FLOODING...

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