Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 301435 AAB AFDLWX AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1035 AM EDT MON MAR 30 2015 .SYNOPSIS...
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A COLD FRONT WILL CROSS THROUGH THE REGION BY LATE THIS AFTERNOON. A REINFORCING CLIPPER LOW WILL PASS OVER THE REGION ON TUESDAY. THE HIGH PRESSURE THAT FOLLOWS WILL SLIDE TO OUR SOUTHEAST THURSDAY AND FRIDAY ALLOWING FOR WARM TEMPERATURES. ANOTHER COLD FRONT IS EXPECTED AT THE END OF THE WEEK.
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&& .NEAR TERM /UNTIL 6 PM THIS EVENING/...
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EVEN W/ A BRIEF BRUSH W/ SOME MIXED PTYPES OVERNIGHT FROM A LOW- LEVEL JET-INDUCED PRECIP BATCH...OVERNIGHT LOWS ONLY MADE IT TO THE L40S ACROSS MUCH OF THE REGION. DEWPOINTS HAVE BEEN FAIRLY MODERATED IN THE 20S/30S...HELPING TO KEEP THE TEMPS MODERATED AS WELL. A COMPLEX AND LARGE UPPER LEVEL TROUGH IS NOW PLACED OVERHEAD...PUSHING A SERIES OF MINOR UPPER VORTS OVER THE EAST COAST. THE ONE SLIDING OVER OUR AREA WILL DO SO LATER THIS AFTN...JUST BEHIND THE SFC COLD FRONT. THE FRONT IS BASICALLY SWITCHING THE WIND DIRECTION FROM THE SW TO WNW...AND KICKING UP SOME BREEZES IN THE 20-30MPH RANGE. AS THE UPPER VORT SWINGS THRU DURING THE MIDDLE AFTN HRS...THE BEST MIXING WILL OCCUR W/ THIS FEATURE - BRINGING DOWN THE GUSTS IN THE 25-35MPH RANGE ESPEC OVER NERN MD. TEMPS BEHIND THE FRONT WILL INCREASE...HELPED OUT A BIT BY DOWNSLOPING...GIVING THE AREA MAX TEMPS IN THE 50S AND L60S OVER THE NRN VA PIEDMONT. USED A MAV/EURO BLEND FOR HIGHS TODAY.
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&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
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HIGH PRESSURE BUILDS IN BRIEFLY MONDAY NIGHT...WITH NO PRECIP EXPECTED. WINDS WILL DIMINISH AND SHIFT TO THE SW. LOW TEMPS MAINLY IN THE UPPER 30S AND LOW 40S...WITH SOME COOLER SPOTS NEAR THE MASON DIXON LINE...ALONG THE RIDGE TOPS AND IN SHELTERED VALLEYS. CLIPPER LOW DIVES ACROSS THE REGION TUESDAY. STILL SOME MODEL UNCERTAINTY OVER HOW FAR SOUTH THE LOW DROPS AS IT CROSSES THE REGION...WITH 00Z GFS AND NAM KEEPING IT CLOSER TO THE MASON DIXON LINE AND THE ECMWF BRINGING IT FURTHER SOUTH ACROSS VA. EARLY MORNING TEMPS SUPPORT POTENTIAL FOR A RAIN/SNOW MIX OVER THE HIGHLANDS. FOR THE REST OF THE AREA...ANY PRECIP SHOULD BE WELL ENOUGH INTO THE MORNING AND AFTERNOON THAT PRECIP WOULD BE RAIN. HIGHS BASED ON WARMER MAV GUIDANCE...MAINLY IN THE 60S WITH SOME PORTIONS OF THE CENTRAL FOOTHILLS AND PIEDMONT REACHING 70.
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&& .LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/... A FEW POPS LINGER TUESDAY EVENING ON WRAP AROUND OF REINFORCING CLIPPER. COLD FRONT SURGES THROUGH AREA...WITH PLENTY OF DRY AIR TO END POPS BY MIDNIGHT. SURGE OF NWLY/NLY AIR WITH CLIPPER COLD FRONT WITH OVERNIGHT 30 TO POSSIBLY 40 MPH WIND GUSTS. HIGH PRESSURE MOVE SE ACROSS SWRN LWX ZONES WEDNESDAY WITH DRY PERIOD AND NEAR TO BELOW NORMAL TEMPERATURES INTO THURSDAY. NLY FLOW FROM WED BECOMES RETURN FLOW WEDNESDAY NIGHT ON BACKSIDE OF HIGH. WARMING TREND THEN THURSDAY AND FRIDAY. WITH DRY AND SUNNY CONDITIONS...THURSDAY MAY BE WARMEST DAY OF THE WEEK. HOWEVER...GUIDANCE STILL HAS FRIDAY WARMER DESPITE A FRONT CROSSING DURING PEAK HEATING. POSSIBLE EXTENDED RAIN EVENT AS A WARM FRONT SETS UP OVER THE AREA FRIDAY AND A COLD FRONT CROSSING FRIDAY NIGHT. BERMUDA HIGH OPENS GULF WITH PLENTY OF MOISTURE. LATER SHIFTS WILL NEED TO MONITOR FOR HEAVY RAIN/FLOODING POTENTIAL. && .AVIATION /14Z MONDAY THROUGH FRIDAY/...
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PRIMARILY VFR W/ THE BKN050 CIGS AND GUSTY WINDS THE MAIN CONCERN THIS MRNG/AFTN. PRECIP HAS MOVED OUT OF THE AREA AND THE CLOUD DECK IS BEGINNING TO DISPERSE BUT THE GUSTY WNW WINDS WILL PICK UP W/IN THE NEXT COUPLE HRS AND CONTINUE THRU NEAR 00Z THIS EVE. GUSTS MAINLY AROUND 20KT...BUT MAY PEAK NEAR 30KTS AT TIMES. WINDS WILL DIMINISH MONDAY NIGHT. YET ANOTHER QUICK-MOVING UPPER LEVEL LOW WILL SWING BY THE AREA ON TUE...MAINLY DURING THE DAYTIME HRS. ANY PCPN IS EXPECTED TO BE RAIN...W/ WARMER TEMPS WORKING INTO THE SRN END OF THE SYSTEM AS IT PASSES BY. BRIEF MVFR CIGS COULD RESULT FROM THIS SYSTEM DURING THE DAYTIME HRS. COLD FRONT CROSSES TUESDAY EVENING WITH RAIN QUICKLY ENDING BY SUNSET AND NWLY FLOW SURGING TO 30 KT OR SO THROUGH THE NIGHT. HIGH PRESSURE CROSSES WEDNESDAY WITH RETURN FLOW THEN WEDNESDAY NIGHT INTO FRIDAY AHEAD OF THE NEXT COLD FRONT THAT CROSSES FRIDAY NIGHT.
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&& .MARINE...
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SCA REMAINS IN EFFECT FOR ALL THE BAY/TP TODAY. A COLD FRONT WILL CONTINUE TO SWING THRU THE REGION INTO THE EARLY AFTN...SHIFTING WINDS FROM THE S-SW TO THE W-NW. HIGHEST GUSTS SHOULD BE AROUND 25-30 KTS. CANNOT RULE OUT GALES ENTIRELY...BUT IT WOULD REQUIRE MIXING TO THE TOP OF THE BOUNDARY LAYER AND IS NOT SUPPORTED BY A MODEL CONSENSUS. WINDS DIMINISH MONDAY NIGHT WITH HIGH PRESSURE BRIEFLY BUILDING IN. A SCA MAY BE NEEDED AGAIN TUESDAY AS ANOTHER COLD FRONT CROSSES THE REGION. SCA EXPECTED ALL WATERS TUESDAY NIGHT AS COLD FRONT CROSSES THE AREA. HIGH PRESSURE SHIFTS SE OVER INTERIOR MID-ATLANTIC WEDNESDAY...SCA LIKELY THROUGH MIDDAY BEFORE CALMING. RETURN FLOW THEN DEVELOPS WEDNESDAY AND PERSISTS THROUGH FRIDAY AHEAD OF THE NEXT COLD FRONT CROSSING FRIDAY NIGHT.
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&& .FIRE WEATHER...
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A COUPLE OF QUICK-MOVING LOW PRESSURE SYSTEMS W/ DRY AIR AND BREEZY CONDS - ONE TODAY AND ANOTHER TMRW - WILL SET UP PARTS OF THE AREA FOR ENHANCED FIRE WX CONCERNS. A DAY OF BREEZY NW WINDS TODAY AND GUSTY SW WINDS ON TUE WILL HELP DRY OUT FUEL MOISTURES OVER THE SW PORTION OF THE AREA - THE LOWER NRN SHEN VLY/N CNTL VA PIEDMONT. A FIRE DANGER STATEMENT MAY BE NEEDED FOR TUE IF CLOUDS AND PRECIP STAY NORTH OF THESE AREAS AND GUSTY WINDS DROP RH VALUES DOWN INTO THE 20-30 PERCENT RANGE.
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&& .TIDES/COASTAL FLOODING...
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WATER LEVELS ARE NOW RUNNING OVER A FOOT ABOVE ASTRONOMICAL PREDICTIONS...SOME LOCALES ALONG THE CHES BAY AT NEARLY 1.5 FT ABOVE...DUE TO THE RETURN OF S-SW WINDS GUSTING THE 15-20KT RANGE. A COLD FRONT WILL SWITCH WINDS TO A MORE W-NW DIRECTION LATER THIS AFTN...GRADUALLY DROPPING THESE VALUES BACK TOWARD A MORE AVG RANGE. THIS WILL ALSO CREATE THE POTENTIAL FOR BLOWOUT TIDES OVERNIGHT...THOUGH SW WINDS WILL AGAIN PICK UP ON TUE MRNG W/ A SIMILAR INCREASE POSSIBLE DURING THE DAY TMRW.
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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 8 PM EDT THIS EVENING FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 11 AM TO 6 PM EDT TUESDAY FOR ANZ530>543.
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&& $$ SYNOPSIS...KS NEAR TERM...KS SHORT TERM...KS LONG TERM...BAJ AVIATION...BAJ/KS MARINE...BAJ/KS FIRE WEATHER... TIDES/COASTAL FLOODING...

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