Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 011849 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 249 PM EDT FRI MAY 1 2015 .SYNOPSIS...
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LOW PRESSURE WILL PULL AWAY FROM CAPE HATTERAS TONIGHT. HIGH PRESSURE WILL BUILD SATURDAY AND SATURDAY NIGHT BEFORE DROPPING TO OUR SOUTH EARLY NEXT WEEK. A COLD FRONT MAY IMPACT THE AREA DURING THE MIDDLE PORTION OF NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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SFC LOPRES REMAINS OFF HSE TAFTN...MVG NEWD. NEWD FLOW ARND LOW AFFECTING ERN HALF OF CWFA. MEANWHILE...HIPRES RDG OVER THE MS RIVER VLY PRESSING EWD...CREATING A CNVGNC ZONE OVER MTNS. LIFT FM THE CNVGNC COMBINED W/ TRRN CIRCULATIONS HV PROVIDED NCSRY FORCING FOR SHRA TO DVLP ALONG THE SPINE OF THE APLCNS TAFTN. SYNOPTIC AND MESOSCALE GDNC HV ALL BEEN CONSISTENT IN TAKING THIS ACTIVITY EWD INTO THE EVNG. INSTBY MINIMAL BUT PRESENT. LAPSE RATES DECENT THRU H4. FOR THE MOST PART...THINK WE/LL JUST BE DEALING WITH SHRA...BUT WUD NOT RULE OUT A TSRA OR TWO. HV TAKEN THOUGHT PROCESS FM ERLR TDA AND CARRIED PCPN A BIT FURTHER EAST. ONLY LKLYS IN THE MTNS LT TAFTN...OTRW HV POPS DWINDLING THRU CHC TO SCHC BY MIDNGT. DOUBT ANY PCPN WL SURVIVE LONGER THAN THAT...BUT CLDS WL. HV DRIER AIR ADVECTING EWD BHD PCPN AXIS...WHICH IS WHAT WUD PERMIT PRTL CLRG. MIN-T IN PRETTY GOOD AGREEMENT...AND DIDNT STRAY FAR. LOW TEMPS IN THE 40S WL BE FAIRLY COMMON AREAWIDE.
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&& .SHORT TERM /SATURDAY THROUGH MONDAY/...
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THE CONVERGENT AXIS WL CONT TO MV EWD SAT AS HIPRES BLDS. IN DAYTIME HEATING...THAT MAY ONCE AGN YIELD A FEW SHRA...PRIMARILY IN THE AFTN. AT THAT POINT...THE AXIS SHUD BE ORIENTED ROUGHLY OVER I-95. LTST POP GDNC BACKING OFF A BIT...BUT STILL SEE THE SIGNAL IN WIND FIELDS AS WELL AS QPF OUTPUT. WL CONT W/ SCHC POPS. THE STRUGGLE W/ BE IN CLDCVR WHICH OTRW WL BE QUITE LMTD IN NW FLOW WITH DEWPTS IN THE 40S. BENIGN WX BEGINS SAT NGT AS RDG BLDS AND SKIES CLR. WENT A BIT ON THE HIGH SIDE OF MOS FOR TEMPS...BOTH MAXT AND MIN-T. HIGH PRESSURE WILL MOVE OVERHEAD SUNDAY INTO MONDAY BRINGING MAINLY CLEAR AND SEASONABLY WARM CONDITIONS. HIGHS SUNDAY WILL TOP OUT IN THE 70S OVER MOST OF THE AREA...EXCEPT NEAR 80 OVER THE CENTRAL VIRGINIA PIEDMONT AND IN THE DOWNTOWN AREAS...AND UPPER 60S OVER THE HIGHER TERRAIN. LOWS SUNDAY NIGHT WILL DROP INTO THE UPPER 40S AND 50S. AS HIGH PRESSURE SHIFTS OFFSHORE OF THE CAROLINA COAST...A SOUTHWESTERLY RETURN FLOW WILL BEGIN TO ESTABLISH ITSELF ON MONDAY LEADING TO SLIGHTLY WARMER AND MORE HUMID CONDITIONS. HIGHS WILL BE IN THE 70S TO LOWER 80S...WHICH IS ABOUT 5 TO 10 DEGREES ABOVE NORMAL FOR THE BEGINNING OF MAY.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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HIGH PRESSURE TO THE SE WILL BE MOVING AWAY MON NIGHT INTO TUE. COLD FRONT WILL APPROACH FROM THE N TUESDAY BRINGING A FEW SHOWERS TO THE REGION. THUNDERSTORMS CANNOT BE RULED OUT DURING THE AFTERNOON AND EVENING HOURS ACROSS THE CWA. THE COLD FRONT WILL MOVE INTO THE REGION TUE NIGHT INTO WED BEFORE IT STALLS OVERHEAD WED INTO THUR. THIS MAY TRIGGER A FEW SHOWERS AND THUNDERSTORMS FOR WED AND THUR...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. THE COLD FRONT WILL LIFT N AS A WARM FRONT ON FRI. WARM CONDITIONS WILL PERSIST TUES THROUGH FRI WITH MAX TEMPS APPROX 10 DEG ABOVE AVERAGE...REACHING THE 80S FOR MOST LOCATIONS.
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&& .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
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AT THIS POINT...ALL TERMINALS ARE VFR AND SHUD REMAIN THAT WAY THRU THIS EVNG. A CONVERGENT ZONE WL BE MVG SLOWLY EWD ACRS THE AREA TNGT...WHICH MAY SPARK A SHRA OR PERHAPS EVEN A TSRA. IAD-CHO WL BE ON THE ERN EDGE OF AREA POTENTIALLY AFFECTED. CVRG/CONFIDENCE AT ANY GIVEN POINT MUCH TOO LOW FOR TAF INCLUSION. WL HV A BKN CLD DECK ARND 035-040...WHICH WL SLOWLY LIFT TAFTN-TNGT. WINDS N/NE BEFORE AXIS WL BECOME MORE NWLY IN ITS WAKE. SPDS SHUD REMAIN BLO 10 KT REGARDLESS. CNVGNC WL BE CROSSING METROS MIDDAY SAT. ONCE AGN THERE CUD BE A STRAY SHRA. OTRW...VFR. NW WINDS UP TO 10 KT. NSW SAT NGT. VFR SUN-MON. NWLY FLOW AOB 10 KT SUN BECOMES SWLY MON. VFR SHUD MAINLY PREVAIL TUE-WED. HWVR...THERE CUD BE A FEW SHRA/TSRA...WHICH MAY PRODUCE RESTRICTIONS IF/WHEN/WHERE THEY DVLP.
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&& .MARINE...
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AS XPCTD FLOW HAS LESSENED ACRS THE WATERS. SRN ZONES ONLY PLACE WHERE SCA REMAINS...AND THATS BY A THREAD. WUD ANTICIPATE CANCELLATION SHORTLY. NOT MUCH OF A WIND HAZARD NEXT 36 HRS. WINDS NELY TNGT INTO TMRW... BCMG VRBL. SPDS ALL AOB 10 KT. A LIGHT GRADIENT WITH HIGH PRESSURE MOVING OVER THE WATERS WILL RESULT IN SUB-SCA WINDS SUNDAY INTO MONDAY. AS THE HIGH SHIFTS OFFSHORE...SOUTHWESTERLY FLOW WILL INCREASE WITH NEAR SCA GUSTS POSSIBLE BY MONDAY EVENING.
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&& .TIDES/COASTAL FLOODING...
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A NORTHEAST FLOW HAS CAUSED TIDAL ANOMALIES TO INCREASE TO AROUND ONE-HALF TO ONE FOOT ABOVE NORMAL ACROSS THE CHESAPEAKE BAY AND TIDAL POTOMAC RIVER. THE NORTHEAST WINDS WILL CONTINUE THROUGH TONIGHT...LIKELY KEEPING WATER LEVELS ELEVATED ACROSS THE BAY AND TIDAL POTOMAC RIVER. MINOR TIDAL FLOODING IS NOT EXPECTED TODAY SINCE THE CURRENT HIGH TIDE WILL BE THE LOWER OF THE TWO. THE ANOMALIES SHOULD HOLD OR PERHAPS EVEN INCREASE A BIT THROUGH TONIGHT. IF THIS OCCURS...THEN WATER LEVELS MAY COME CLOSE TO MINOR FLOODING THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY SATURDAY. LATEST GDNC SUGGESTS WE WL SQUEEZE JUST UNDER ADVY THRESHOLD. HOWEVER SAT NGT-SUN MRNG WILL BE A CONCERN.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR ANZ534- 537-543.
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&& $$ SYNOPSIS...HTS NEAR TERM...HTS SHORT TERM...HTS/DFH LONG TERM...IMR AVIATION...HTS/DFH MARINE...HTS/DFH TIDES/COASTAL FLOODING...BJL/HTS

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