Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 190817 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 417 AM EDT SUN APR 19 2015 .SYNOPSIS... HIGH PRESSURE CENTERED TO THE NORTH OF THE AREA WILL MOVE OFF THE NEW ENGLAND COAST LATE TODAY. LOW PRESSURE ORGANIZING OVER THE DEEP SOUTH WILL MOVE NORTHWARD TODAY...AND WILL PUSH A WARM FRONT THROUGH THE LOCAL AREA TONIGHT. A COLD FRONT THEN CROSSES THE AREA MONDAY NIGHT. HIGH PRESSURE BUILDS BACK IN FROM THE SOUTHWEST ON TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... SFC HIGH PRESSURE CENTERED OVER THE EASTERN GREAT LAKES IS WELL ENTRENCHED OVER THE FA THIS MORNING. A WEAK FRONTAL BOUNDARY CURRENTLY RESIDES ALONG THE MASON-DIXON LINE AND WILL MOVE SOUTHWARD INTO NOVA AND LOWER MARYLAND OVER THE NEXT FEW HOURS BEFORE WASHING OUT. A VEIL OF THIN HIGH CLOUDS CURRENTLY COVERS MUCH OF THE FA...WITH SOME LOWER CLOUDS ALONG THE ALBEMARLE SOUND. ALSO NOTICING PATCHY FOG DEVELOPING THIS MORNING AND WILL CONTINUE TO MONITOR TO SEE IF IT BECOMES LOCALLY DENSE. OTW...SFC HIGH PRESSURE TO THE NORTH SHIFTS OFF THE COAST BY THIS AFTN WITH LOW LVL FLOW BECOMING E-SE. MEANWHILE...LOW PRESSURE WILL BE TRACKING NORTH TOWARD THE LOWER GREAT LAKES STATES...PUSHING A WARM FRONT NE TOWARD THE MID-ATLANTIC REGION BY THIS EVENING. SUNSHINE WILL PEAK THROUGH THE HIGH CLOUDS TO START TODAY (A LITTLE LESS SUN WHERE LOW CLOUDS/PATCHY FOG START)...THEN EXPECTING INCREASING CLOUDS MIDDAY THROUGH THE AFTN (FROM SW-NE) IN ADVANCE OF THE WARM FRONT. LATEST MODELS IN GOOD AGREEMENT WRT TIMING OF ARRIVAL OF RAIN. HAVE CHC POPS AS FAR EAST AS A LINE FROM LKU-RIC-NTU BY 16-18Z...INCREASING TO LIKELY/CATEGORICAL POPS (EXCEPT CHC POPS LOWER MD EASTERN SHORE) BY 00Z. HIGH TEMPS IN THE MID UPR 60S...WITH SOME LOW 70S SE. SIGNIFICANT INFLOW OF DEEP LAYERED MOISTURE INTO THE REGION TONIGHT AS A WARM FRONT MAKES PROGRESS NE THROUGH THE FA. MAY BE PERIODS OF MODERATE/HEAVY RAIN...AND WOULD NOT RULE OUT ISOLD (ELEVATED) THUNDER. MAJORITY OF THE RAIN SHIFTS TO THE COAST BY 12Z MONDAY...SO WILL SHOW LOWERING POPS FROM WEST TO EAST AFTER 06Z TONIGHT. RAIN MAY BE ALL OVER IN OUR FAR WESTERN COUNTIES BY DAYBREAK. TOTAL QPF AMOUNTS THRU TONIGHT WILL RANGE FROM 0.75"-1.50" WITH LOCALLY HIGHER AMOUNTS UP TO 2.00". DESPITE THE POTENTIAL FOR BRIEF HEAVY RAIN...PCPN AMOUNTS WILL REMAIN BELOW 6-12HR FLASH FLOOD GUIDANCE SO A FLASH FLOOD WATCH IS NOT NECESSARY. LOWS TONIGHT FROM THE MID 50S TO MID 60S. && .SHORT TERM /MONDAY THROUGH TUESDAY/... THE AREA OF RAIN WILL SHIFT OFF THE COAST MON MORN...THEN CONCERN SHIFTS TO A TROUGH ALOFT APPROACHING FROM THE WEST BY LATE MON AFTN/EVE (LIKELY LEADING TO SCT SHWRS/TSTMS). SPC CURRENTLY HAS 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 CONTINUE TO HIGHLIGHT POSSIBLE STRONG/ISOLD SVR STORMS IN THE HWO FOR LATE MON AFTN/EVE. OTW...VRB CLOUDS-PARTLY SUNNY MIDDAY/AFTN ON MON. HIGH TEMPS IN THE 70S AT THE CST...80 TO 85 ELSEWHERE. COLD FRONT CROSSES THE FA MON NIGHT WITH CHC POPS (HIGHEST NNE- CNTRL)...THEN DRYING/COOLER WESTERLY FLOW TAKING OVR INTO TUE. PARTLY/MOSTLY SUNNY TUE WITH HIGH TEMPS IN THE UPR 60S TO NR 70 AT THE COAST...AND LOW/MID 70S ELSEWHERE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... UPPER LOW REMAINS IN VIC OF THE GREAT LAKES THRU THE EXTENDED PERIOD THANKS TO BLOCKY FLOW OVER THE HIGHER LATITUDES. FAST WLY/ZONAL FLOW PROGGED OVER THE LOCAL AREA. SFC HIGH PRESSURE BUILDS OVER THE SE STATES/SRN MID ATLANTIC TUES NIGHT-WEDS MORNING...SLIDING OFFSHORE WEDS AFTERNOON. THE RESULT IS A MOSTLY SUNNY TO PARTLY CLOUDY SKY WEDS WITH HIGHS RIGHT AROUND NORMAL...UPPER 60S TO 70 INLAND AND MID- UPPER 60S COASTAL AREAS. POTENT SHORTWAVE ROUNDS THE BASE OF THE STACKED UPPER LOW INTO THE OH VALLEY LATE WEDS-WEDS NIGHT. ASSOCIATED FAST MOVING COLD FRONT REACHED THE CNTRL APPALACHIANS WEDS NIGHT...CROSSING THE LOCAL AREA EARLY THURS. FRONT EXPECTED TO STALL VIC NC THURS NIGHT DUE TO WLY FLOW ALOFT. QUESTION WILL BE HOW MUCH MOISTURE RETURN THERE IS THURS AS ECMWF REMAINS DRY AND THE GFS RATHER MOIST. DIFFERENCE IS LOW LEVEL SWLY FLOW IN GFS COMPARED TO WLY FLOW IN THE ECMWF. TRENDED TOWARD DRIER ECMWF...DROPPING POPS TO SILENT THURS-THURS NIGHT. HIGHS THURS REMAINING AROUND NORMAL...GENERALLY IN THE MID-UPPER 60S. COOL CANADIAN HIGH PRESSURE PROGGED TO BUILD INTO THE OH VALLEY THURS NIGHT-FRI...EXTENDING INTO THE MID-ATLANTIC REGION. THE RESULT WILL BE DRY CONDITIONS...NWLY WINDS AND BELOW NORMAL TEMPS FRI...GENERALLY IN THE LOW-MID 60S INLAND TO UPPER 50S-LOW 60S COASTAL AREAS. MODELS PICKING UP ON A SRN STREAM SYSTEM CROSSING THE SE STATES SAT. MENTIONED SLIGHT CHANCE POPS SRN VA/NE NC...CLOSEST TO THE FRONTAL BOUNDARY AND BEST MOISTURE RETURN. && .AVIATION /08Z SUNDAY THROUGH THURSDAY/... A BACKDOOR COLD FRONT DROPPING SSW OVER MD/DE AS OF 06Z WILL PASS ACROSS THE REGION EARLY THIS MORNING. AHEAD OF THE FRONT...FOG/STRATUS IS POSSIBLE ACROSS SE VA/NE NC. PHF/ORF/ECG HAVE THE BEST POTENTIAL FOR EXPERIENCING IFR CONDITIONS...WHILE AN EARLIER FRONTAL PASSAGE AT SBY SHOULD LARGELY INHIBIT FOG. RELATIVELY DRIER CONDITIONS INLAND WILL GREATLY REDUCE THE FOG POTENTIAL AT RIC. THE WIND WILL BECOME ENE BEHIND THE FRONT...WITH SPEEDS INCREASING TO 10-15KT TODAY INLAND...AND 15-20KT WITH GUSTS ~25KT ALONG THE COAST. THE FRONT WILL LIFT BACK NE AS A WARM FRONT LATER TODAY INTO TONIGHT AHEAD OF A COMPLEX LOW PRESSURE SYSTEM OVER THE CENTRAL US. RA AND ASSOCIATED DEGRADED FLIGHT CONDITIONS ARE EXPECTED TO AFFECT ALL AREAS LATER TODAY INTO TONIGHT...WITH RA DIMINISHING FROM SW-NE DURING THE 08Z TO 13Z TIME FRAME 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... A BACKDOOR COLD FRONT PRESENTLY ENTERNING THE NRN OCEAN ZONES WILL DROP N-S ALONG THE COAST EARLY THIS MORNING. THIS WILL PRODUCE A WIND SHIFT TO NE. SPEEDS ARE EXPECTED TO AVERAGE 10- 15KT...ALTHOUGH SPEEDS COULD BRIEFLY REACH 20KT IN THE IMMEDIATE WAKE OF THE BOUNDARY THIS MORNING. OTHERWISE...LOW PRESSURE LIFTS INTO THE ERN GREAT LAKES THIS AFTERNOON/EVENING...WITH SECONDARY LOW PRESSURE DEVELOPING OVER THE MID ATLANTIC TONIGHT. THIS IS A FAVORABLE PATTERN FOR A SHORT DURATION (~3-5 HR)OF STRONG SCA CONDITIONS IN SE FLOW. AT THIS TIME IT APPEARS TO BE CENTERED AROUND 09Z TONIGHT. WIND SPEEDS ARE EXPECTED TO INCREASE TO 15-20KT THIS AFTERNOON AND EVENING...BEFORE INCREASING TO 20-25KT WITH GUSTS ~30KT LATER TONIGHT INTO EARLY MONDAY. SEAS BUILD TO 4-5FT TODAY...AND THEN 5-7FT TONIGHT...BEFORE BEGINNING TO GRADUALLY SUBSIDE MONDAY AS THE FLOW BECOMES SOUTHERLY AND THE PRESSURE GRADIENT RELAXES. INHERITED SCAS REMAIN SIMILAR. THE MAIN CHANGES WERE TO ADD THE UPPER JAMES...AND EXTEND THE BAY/SOUND/RIVERS SEGMENTS THROUGH 10AM MONDAY. ADDITIONALLY...THE NRN OCEAN ZONES (N OF PARRAMORE ISLAND) WERE EXTENDED THROUGH MONDAY NIGHT WHERE SEAS WILL REMAIN 4-5FT. A COLD FRONT APPROACHES FROM THE W MONDAY AFTERNOON/EVENING...AND MOVES ACROSS THE COAST LATE MONDAY NIGHT. THIS FRONT IS EXPECTED TO TRIGGER SHOWERS/TSTMS...WHICH WILL HAVE THE POTENTIAL OF PRODUCING STRONG WIND GUSTS. HIGH PRESSURE BUILDS ACROSS THE SOUTHEAST TUESDAY AND WEDNESDAY AS LOW PRESSURE LINGERS OVER THE GREAT LAKES. A WEAK COLD FRONT CROSSES THE REGION WEDNESDAY NIGHT INTO THURSDAY. && .TIDES/COASTAL FLOODING... PERIOD OF ONSHORE FLOW IS EXPECTED THROUGH SUNDAY...BEFORE WINDS SWITCH TO THE SOUTH SUNDAY NIGHT AND MONDAY. THE RESULT WILL BE TIDAL ANOMALIES AROUND 1 FT ABOVE NORMAL MOST TIDAL GAGES. 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 UPPER BAY AND OCEAN CITY WILL APPROACH MINOR FLOODING THRESHOLDS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 AM EDT MONDAY FOR ANZ630>636-638. SMALL CRAFT ADVISORY FROM NOON TODAY TO 6 PM EDT MONDAY FOR ANZ650-652-654. SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 PM EDT MONDAY FOR ANZ656-658. && $$ SYNOPSIS...JDM NEAR TERM...JDM SHORT TERM...ALB/JDM LONG TERM...SAM AVIATION...AJZ MARINE...AJZ TIDES/COASTAL FLOODING...AKQ

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