Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 290047 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 847 PM EDT THU APR 28 2016 .SYNOPSIS...
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A COLD FRONT WILL REMAIN STALLED TO THE SOUTH THROUGH FRIDAY. WAVES OF LOW PRESSURE WILL RIDE ALONG THE BOUNDARY DURING THIS TIME. THE BOUNDARY WILL DROP AS FRONTS AND LOW PRESS SYSTEM MOVES THROUGH THE MID- ATLANTIC BRINGING SHOWERS INTO THE REGION... MAINLY SUN INTO MON NIGHT.FARTHER SOUTH SATURDAY...BUT IT WILL THEN LIFT NORTHWARD CLOSER TO THE REGION AGAIN SUNDAY AND MONDAY AS ANOTHER WAVE OF LOW PRESSURE MOVES ALONG IT.
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&& .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
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A NEARLY STATIONARY BOUNDARY REMAINS DRAPED OVER THE ALLEGHENY HIGHLANDS INTO SOUTHERN VIRGINIA AND NORTHEASTERN NORTH CAROLINA. THE BOUNDARY WILL REMAIN NEARLY STATIONARY THROUGH TONIGHT...WHICH MEANS THAT COOL NORTHEAST WINDS WILL PERSIST OVER THE AREA. MIN TEMPS WILL RANGE FROM THE LOWER TO MIDDLE 40S ALONG THE MASON- DIXON LINE TO LOWER AND MIDDLE 50S IN THE CENTRAL SHENANDOAH VALLEY. AN ONSHORE FLOW WILL CONTINUE TO CAUSE LOW-LEVEL MOISTURE TO BE TRAPPED UNDERNEATH THE SUBSIDENCE INVERSION...RESULTING IN LOW CLOUDS ALONG WITH AREAS OF FOG. WARM AND MOIST AIR WILL CONTINUE TO OVERRUN THE COOL AIR IN PLACE...RESULTING IN DRIZZLE AND PERHAPS EVEN LIGHT RAIN. A PERIOD OF STEADIER RAIN IS LIKELY THIS EVENING FOR MOST AREAS THIS EVENING. THIS IS BECAUSE OF SHOWERS AND THUNDERSTORMS THAT POPPED UP TO OUR WEST IN THE WARM AIR THIS AFTERNOON. THE ACTIVITY IS PASSING THROUGH THIS EVENING...AND IT IS WEAKENING DUE TO THE COOLER AIR BUT STILL PRODUCING PERIODS OF STEADIER RAIN.
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&& .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
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ZONAL H5 FLOW/ELY SFC FLOW WL CONT INTO FRI...AS S/WV ENERGY TRACKS EWD N OF CWFA. CHC TO LIKELY POPS PREVAIL...HIEST ACROSS THE NORTHERN HALF OF THE CWA. DONT BELIEVE PCPN WL BE ALL THAT MEANINGFUL. WL HV WEAK RDGG IN THE WAKE OF THE S/WV FRI NGT. THIS IS THE BEST CHC AT A DRY PD FOR THIS FCST CYCLE. AFTER LINGERING EVNG POPS... PRESERVED 10 POPS/PATCHY DZ WORDING FOR THE OVNGT HRS. WAA/ISENT LIFT IMPRV SAT-SAT NGT AS AN AMPLIFIED TROF AXIS IN THE SRN PLAINS EJECTS TWD CWFA. POPS WL BE STAIR-STEPPED UPWD AS THIS FORCING APPROACHES. LKLY SHRA BY SAT NGT. IT CUD BE ERLR PENDING ANY TIMING ADJUSTMENTS IN LATER GDNC RUNS. CWFA WL REMAIN ON THE COOL SIDE OF THE STALLED BNDRY THRUT THIS PD. TEMPS REFLECT A MDL BLEND/PERSISTENCE TYPE FCST...WHICH CAPTURE THE LACK OF DIURNAL RANGE.
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&& .LONG TERM /SUNDAY THROUGH THURSDAY/... LOW PRESS OVER THE OHIO VALLEY AND ITS ASSOCIATED WARM FRONT WILL BE LIFTING NORTH ON SUN... MOVING ACROSS THE REGION AND BRINGING SHOWERS TO OUR CWA. THE LOW PRESS WILL TRACK EAST AND MOVE OFF OF THE MID-ATLANTIC COAST SUN NIGHT INTO EARLY MON... WITH ITS ASSOCIATED COLD FRONT. GUIDANCE DIFFERS ON TUE TO WED NIGHT CONDITIONS... WITH GFS BEING DRIER... BUT BRINGING SHOWERS DUE TO A SHORTWAVE TROUGH ON TUE... WHILE EURO KEEPS A BOUNDARY STALLING TO OUR SE AND WAVES OF LOW PRESS MOVING THROUGH IT... THEREFORE KEEPING MAINLY THE SOUTHERN PART OF OUR CWA WITH HIGHER CHANCES OF PRECIP. COLD FRONT APPROACHES ON THU. TEMPS WILL BE NEAR OR SLIGHTLY BELOW NORMAL. && .AVIATION /01Z FRIDAY THROUGH TUESDAY/...
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IFR CONDITIONS ALONG WITH PERIODS OF DRIZZLE AND EVEN SOME RAIN AT TIMES WILL CONTINUE TONIGHT. MVFR CONDITIONS STILL PERSIST ACROSS KBWI AND KMTN THIS EVENING DUE TO SOME DRIER AIR. HOWEVER...IFR CONDITIONS ARE EXPECTED TO DEVELOP ACROSS THESE AREAS OVERNIGHT. THE IFR CONDITIONS WILL PERSIST THROUGH MOST OF FRIDAY...BUT MAY LIFT TO MVFR LEVELS SOMETIME FRIDAY AFTERNOON INTO EARLY FRIDAY EVENING. MORE IFR CONDITIONS ARE EXPECTED FRIDAY NIGHT. PERIODS OF DRIZZLE AND POSSIBLE LIGHT RAIN ARE POSSIBLE DURING THIS TIME. FRI NGT MAY END UP BEING THE DRIEST PART OF THIS FCST...BUT THAT MAY ALSO MEAN THE FOG CUD BE THE DENSEST. BETTER OPPORTUNITY FOR WIDESPREAD RAIN WL OVERSPREAD THE TERMINALS DURING THE AFTN- EVE SAT. SUB-VFR CONDITIONS POSSIBLE SATURDAY NIGHT INTO MONDAY MORNING AS A BOUNDARY REMAINS STALLED NEAR THE AREA AND LOW PRESSURE TRACKS ALONG IT. THE BOUNDARY WILL PUSH WELL TO OUR SOUTH EARLY NEXT WEEK AND VFR CONDITIONS MAY RETURN..
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&& .MARINE... ELY FLOW 10-15 KT ATTM...WHICH WL BE THE MAIN STORY FOR THE NEXT CPL OF DAYS. DO NOT ANTICIPATE ANY SCA CONDS THRU SAT. SUB-SCA CONDITIONS EXPECTED DURING THIS PERIOD AS WINDS WILL BE BELOW CRITERIA. SHOWERS EXPECTED MAINLY SUN INTO MON NIGHT. && .TIDES/COASTAL FLOODING...
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WATER ANOMALIES HAVE BEEN SLOWLY FALLING AND AS HIDE TIDE AS PASSED...WATER LEVELS HAVE FALLEN BELOW FLOOD STAGE. THE HIDE TIDE CYCLE THIS EVENING IS NOT EXPECTED TO CAUSE ANY FLOODING CONCERNS...BUT FRIDAY MORNINGS CYCLE MAY ONCE AGAIN CAUSE MINOR FLOODING AT ANNAPOLIS .
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HTS NEAR TERM...BJL/HTS SHORT TERM...HTS LONG TERM...IMR AVIATION...BJL/IMR/HTS MARINE...BJL/IMR/HTS TIDES/COASTAL FLOODING...MJM/BJL

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