Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 281816 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 216 PM EDT SUN SEP 28 2014 .SYNOPSIS...
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HIGH PRESSURE WILL WEAKEN OVER THE REGION MONDAY AS LOW PRESSURE FORMS OVER THE SOUTHEAST GULF COAST STATES. THIS LOW WILL MOVE OFF THE COAST TUESDAY...AS A TROUGH APPROACHES THE MID-ATLANTIC FOR THE MID-WEEK PERIOD. HIGH PRESSURE IS EXPECTED TO RETURN LATE IN THE WEEK. A COLD FRONT MAY PUSH THROUGH THE MID ATLANTIC STATES FRIDAY NIGHT INTO SATURDAY.
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&& .NEAR TERM /THROUGH MONDAY/...
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RIDGE OVER THE MID-ATLANTIC HAS BECOME DIRTY AS A BURST OF WARM ADVECTION ALOFT HAS LED TO SCT-BKN CIRRUS ACROSS THE CWA. REST OF THE AFTERNOON WILL BE PARTLY SUNNY WITH CIRRUS OVERHEAD. TEMPERATURES WILL WARM INTO THE UPPER 70S/LOWER 80S /EXCEPT COOLER OVER THE RIDGE TOPS AND PERHAPS RIGHT ALONG THE CHESAPEAKE BAY/. INFRARED SATELLITE IMAGERY SHOWS PLENTY OF UPSTREAM CIRRUS POISED TO STREAM NORTHEAST THROUGH THE CWA /SUPPORTED BY MODEL RH FIELDS/...AND SKY COVER TRENDS TO MOSTLY CLOUDY TONIGHT. WITH THE CLOUDS...THIS MAY LIMIT THE FOG FORMATION WE/VE SEEN THE PAST SEVERAL MORNINGS BUT PATCHY FOG STILL CAN/T BE RULED OUT IN THOSE TYPICAL FOG PRONE VALLEYS/NEAR-RIVER LOCATIONS. RIDGE WEAKENS OVER THE AREA MONDAY AS LOW PRESSURE DEVELOPS ALONG A BAROCLINIC ZONE ACROSS THE SOUTHEAST STATES. MOST OF THE QPF WILL OCCUR OVER THE CAROLINAS AND POINTS SOUTHWARD PER LATEST MODEL GUIDANCE/ENSEMBLE QPF. HAVE BACKED OFF ON POPS MONDAY...ONLY FOCUSING LOW CHANCE POPS FROM THE POTOMAC HIGHLANDS THROUGH THE CENTRAL SHENANDOAH VALLEY AND INTO THE PIEDMONT. USED MAV/SREFS BLEND FOR TEMPERATURES MONDAY...IT SHOULD BE ANOTHER WARM/ABOVE AVERAGE DAY DESPITE PLENTY OF CLOUDS.
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&& .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/...
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CONTINUED THE TREND OF BACKING OFF ON POPS MONDAY NIGHT INTO MOST OF TUESDAY AS LOW PRESSURE OVER THE SOUTHEAST STATES LOOKS TO MOVE EAST INSTEAD OF NORTHEAST. LITTLE IF ANY QPF IS EXPECTED TO OCCUR THIS FAR NORTH IN ASSOCIATION WITH THAT FEATURE. NORTHERN STREAM LOW HOWEVER WILL APPROACH LATER TUESDAY INTO TUESDAY NIGHT...SO DO HAVE LOW POPS ACROSS THE NORTHWEST TUESDAY AND THEN THROUGHOUT THE CWA TUESDAY NIGHT AS VORT ENERGY ROUNDING THE BASE OF THE LOW WOULD SUPPORT SOME SHOWERS.
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&& .LONG TERM /WEDNESDAY THROUGH SUNDAY/...
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AN AREA OF LOW PRESSURE WILL BE MOVING OUT TO SEA ON WEDNESDAY AS A BROAD AREA OF HIGH PRESSURE REMAINS ENTRENCHED TO THE NORTH. EASTERLY WINDS IN THE LOW LEVELS WILL LIKELY KEEP CLOUDS FAIRLY WIDESPREAD WITH A SHOWER OR TWO NOT OUT OF THE QUESTION...MAINLY OVER THE POTOMAC HIGHLANDS DUE TO ADDED UPSLOPE COMPONENT. RIDING THEN BRIEFLY BUILDS ACROSS THE AREA FOR THURSDAY. BY THE END OF THE WEEK...A LARGE UPPER-LEVEL TROUGH WILL BEGIN DIGGING INTO THE CENTRAL CONUS. AS THIS TROUGH MOVES ACROSS THE GREAT LAKES FRIDAY NIGHT INTO SATURDAY...IT WILL DRAG A COLD FRONT THROUGH THE REGION. THE 12Z GFS IS MORE AMPLIFIED THAN THE 00Z ECMWF...AND ENSEMBLES STILL SHOW SUBSTANTIAL SPREAD REGARDING THE STRENGTH OF THE TROUGH AND FRONT. A SEASONABLY COOL AIRMASS WILL BUILD IN BEHIND THE FRONT TO BEGIN NEXT WEEKEND...BUT TEMPERATURES SHOULD QUICKLY BEGIN TO REBOUND BY THE END OF THE WEEKEND AS HIGH PRESSURE REBUILDS FROM THE SOUTH.
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&& .AVIATION /18Z SUNDAY THROUGH FRIDAY/...
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BROKEN DECK OF CIRRUS DEVELOPS THIS AFTERNOON...LIKELY TO CONTINUE INTO MONDAY. WITH THE CLOUDS...THIS WOULD LIMIT FOG FORMATION TONIGHT BUT CAN/T RULE OUT BRIEF VIS RESTRICTIONS LATE AT NIGHT AT MRB/CHO ESPECIALLY IF THERE ARE BREAKS IN THE CLOUDS THEN. POTENTIAL EXISTS FOR VIS AND/OR CIG RESTRICTIONS TO DEVELOP LATE TUESDAY NIGHT. SUB-VFR CIGS/VSBYS ALSO PSBL WED-WED EVE IN CLOUDS AND -SHRA OR -DZ. WINDS E 10-20 KTS...MOD CONFIDENCE VFR THU W/ WINDS BCMG S 10 KTS AS GUIDANCE HAS COME INTO BETTER AGREEMENT OVER THE PAST 24 HRS.
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&& .MARINE...
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WEAK GRADIENT TODAY...RESULTING IN S/SW WINDS MAINLY AROUND 5 KT. THIS REMAINS THE CASE TONIGHT INTO MONDAY. SHOULD GET A BETTER SOUTHERLY PUSH COME TUESDAY...WHICH MAY INCREASE INTO SCA CRITERIA OVER THE BAY LATE TUESDAY NIGHT. EASTERLY WIND GUSTS COULD BREACH SMALL CRAFT ADVISORY CRITERIA WEDNESDAY. WINDS/SEAS DIMINISH THURSDAY AS HIGH PRESSURE BUILDS BRIEFLY. SMALL CRAFT ADVISORY CONDITIONS WILL BE POSSIBLE FRIDAY NIGHT INTO THE WEEKEND BOTH IN SOUTHERLY CHANNELING AHEAD OF A COLD FRONT FRIDAY NIGHT AND IN A NORTHWEST PRESSURE SURGE OR TWO BEHIND THE FRONT SATURDAY/SECONDARY FRONT SUNDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BPP/DFH NEAR TERM...BPP SHORT TERM...BPP LONG TERM...DFH AVIATION...BPP/DFH MARINE...BPP/DFH

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