Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 221929 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 329 PM EDT WED APR 22 2015 .SYNOPSIS...
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COOLER AND DRIER AIR WILL FOLLOW A STRONG COLD FRONT AS IT MOVES OFF THE COAST THIS EVENING. HIGH PRESSURE WILL BUILD IN FOR THE END OF THE WEEK...BUT STILL KEEP BREEZY CONDITIONS OCCURRING EACH OF THE NEXT COUPLE OF DAYS. ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO MOVE THROUGH THE AREA THIS WEEKEND.
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&& .NEAR TERM /UNTIL 10 PM THIS EVENING/...
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A STRONG COLD FRONT BROUGHT A SHORT-LIVED PERIOD OF GUSTY WINDS THAT IS NOW NEARLY CLEARED THE AREA. SHOWER ACTIVITY CONICIDENT W/ THE BOUNDARY HAD EARLIER SPREAD A MUCH WIDER SWATH ACROSS THE NRN SHEN VLY...JUST ON THE LEE OF THE APLCNS. INVERTED-V SOUNDING W/ STRONG AREA OF SUBSIDENCE HELPED TO MIX DOWN A PORTION OF THE INTENSE MID-LEVEL JET MAX. GUSTS WELL INTO THE 30KT RANGE OUT AHEAD OF THE FRONT BROUGHT TEMPS UP INTO THE L-M70S BRIEFLY LATE THIS MRNG. THE TIMING OF THE FRONT HOWEVER PREVENTED MUCH MORE OF A PEAK AND HAS INSTEAD BROUGHT TEMPS DOWN OVER THE NRN HALF OF THE AREA DOWN ABOUT 10-15F IN MINUTES. THE QUICK PASSAGE OF THE FRONT AND SUBSIDENCE REGION IMMEDIATELY BEHIND IT HAS ALLOWED SKIES TO CLEAR QUICKLY WHICH MAY ULTIMATELY HELP TEMPS INCREASE A COUPLE MORE DEGREES OVER THE NEXT COUPLE OF HRS BEFORE THE STEADY DROP BACK INTO THE 50S AND THEN 40S LATER TONIGHT. BEFORE THEN...A FEW MORE WAVES OF LIGHT/MODERATE RAIN WILL SWING THRU THE AREA AS THE BACK END OF THE SYSTEM GATHERS ITSELF A BIT WHILE THE UPPER JET MAX SLIDES OVERHEAD. WLY WINDS OVER THE NEXT FEW HRS WILL CONTINUE TO GUST IN THE 30-40KT RANGE IN SOME OF ISOLATED SHOWER ACTIVITY AND NEAR 30KT JUST IN THE AMBIENT WIND FIELD OVER THE REGION. CLOSER TO SUNSET...THE MIXING POTENTIAL WILL GRADUALLY DECREASE TO WHERE ONLY THE TOP END GUSTS FROM 20-30KT WILL CONTINUE AND THEN DROP OFF QUICKLY LATER THIS TONIGHT. UPSLOPE SNOW HAS BEEN AFFECTING THE HIGHEST TERRAIN AREAS OF THE CNTRL APLCNS...FROM NEAR FROSTBURG TO BAYARD AND ADJACENT AREAS OF THE ALLEGANY FRONT. THIS ACTIVITY WILL WIND DOWN OVER THE NEXT FEW HRS AS THE TRAPPED MOISTURE IN THE BOUNDARY LAYER MOVES ON TO THE EAST AND OUT OF THE AREA.
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&& .SHORT TERM /10 PM THIS EVENING THROUGH SATURDAY NIGHT/...
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AS PRECIP ENDS ACROSS THE REGION THIS EVE...DRIER AIR WILL FILTER INTO THE AREA AND ALLOW TEMPS TO DROP BACK INTO THE U30S FOR OVERNIGHT LOWS. SOME GUIDANCE GOING A BIT LOWER...KEEPING A MODERATED REGIME OVER THE I-95 CORRIDOR AND MUCH COOLER FOR THE MTNS AND SHEN VLY REGION. UPSLOPE AREAS MAY CONTINUE TO RECEIVE SOME POST-FRONTAL RAIN/SNOW MIX EARLY THURSDAY AS A VORT MAX SWINGS THRU. EAST OF THE MOUNTAINS...THERE WILL ONLY BE AN INCREASE IN CLOUDS THURSDAY. EXPECT BREEZY CONDITIONS ONCE AGAIN ON THURSDAY...BUT MORE IN THE 25 KT RANGE. LOWS MAY FALL BELOW FREEZING IN THE HIGHLANDS TONIGHT...WITH MID 30S-LOW 40S EAST. 850 MB TEMPS DROP BELOW 0C THURSDAY...RESULTING IN HIGHS ONLY IN THE 50S TO AROUND 60. CHILLY OVERNIGHT TEMPERATURES WILL FOLLOW ONCE AGAIN FOR THURSDAY NIGHT WITH LOWS DROPPING BACK TO THE LOW 30S NORTH AND WEST OF THE METRO AREAS TO THE UPPER 30S TO THE LOWER 40S ACROSS THE I-95 CORRIDOR AND SOUTHERN MARYLAND. PATCHY FROST WILL BE POSSIBLE. HIGH PRESSURE WILL REMAIN IN PLACE ON FRIDAY BUT TEMPERATURES WILL REMAIN BELOW NORMAL WITH READINGS MOSTLY IN THE 50S...EXCEPT LOW 60S OVER CENTRAL VA. PATCHY FROST WILL BE POSSIBLE AGAIN FRIDAY NIGHT INTO SATURDAY MORNING. CLOUDS WILL INCREASE FROM WEST TO EAST LATE FRIDAY NIGHT AS LOW PRESSURE APPROACHES FROM THE WEST. LIGHT RAIN/SHOWERS WILL INCREASE FROM SOTHWEST TO NORTHEAST ON SATURDAY AND CONTINUE INTO SATURDAY NIGHT.
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&& .LONG TERM /SUNDAY THROUGH TUESDAY/...
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LOW PRESSURE TO THE SOUTH WILL DEPART INTO THE ATLANTIC SATURDAY NIGHT...WITH ANY RAIN GRADUALLY ENDING. HIGH PRESSURE WILL RETURN FOR THE SECOND HALF OF THE WEEKEND INTO EARLY NEXT WEEK...BEFORE A STRONG TROUGH OF LOW PRESURE APPROACHES THE AREA DURING THE MIDDLE OF NEXT WEEK.
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&& .AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
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FAST-MOVING COLD FRONT SLID ACROSS THE AREA EARLIER AND IS NOW EAST OF THE DC/BALT AREA. A FEW MORE HRS OF SCTD SHOWERS/GUSTY WINDS THEN A DROP OFF TONIGHT. EXPECT ANOTHER BREEZY DAY ON THURSDAY BUT WNW WINDS WILL BE CLOSER TO 20-25 KT. VFR CONDITIONS THURSDAY NIGHT THROUGH FRIDAY NIGHT. MVFR OR IFR CONDITIONS POSSIBLE SATURDAY AND SATURDAY NIGHT DUE TO THE CHANCE OF LIGHT RAIN. VFR CONDITIONS SUNDAY. MAINLY VFR SUN-MON W/ NWLY FLOW 10-15 KT.
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&& .MARINE...
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A COLD FRONT HAS CROSSED MUCH OF THE AREA JUST IN THE PAST COUPLE OF HRS...STILL MOVING THRU THE LOWER BAY. GALE GUSTS WILL CONTINUE OVER THE NEXT FEW HRS BEHIND THE BOUNDARY. WINDS WILL STAY OUT OF THE WEST INTO THE OVERNIGHT HRS...THEN SCA GUSTS TAKE OVER AS WINDS DROP OFF. SCA CONTINUES FOR ALL WATERS THURSDAY AS W WINDS GUST UP TO 25 KT. NO MARINE HAZARDS THURSDAY NIGHT. SMALL CRAFT ADVISORIES POSSIBLE FRIDAY. NO MARINE HAZARDS FRIDAY NIGHT THROUGH SUNDAY. SCA LIKELY SUNDAY IN NWLY SURGE BEHIND FRONT.
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&& .TIDES/COASTAL FLOODING...
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TIDE LEVELS HAVE BECOME ELEVATED OVER THE PAST FEW HRS...ESPEC OVER THE UPPER TIDAL POTOMAC W/ THE PRE-FRONTAL WIND BUILD UP AND THEN EVEN AS THE FRONT MOVED THRU...CHANGING WINDS TO A MORE WLY DIRECTION. WINDS WILL NOW STAY OUT OF THE WEST INTO THE NIGHT HRS...OCCASIONALLY GUSTY AND IS EXPECTED TO BEGIN DROPPING THE POSITIVE ANOMALIES BUT MAY ALSO AFFECT THE NEXT HIGH TIDE CYCLE. WILL MONITOR THESE TRENDS FOR THE NEXT COUPLE OF DAYS...AS WATER LEVELS WILL AT THE VERY LEAST REMAIN ELEVATED.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR MDZ003>005-501- 502. VA...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR VAZ025>031-040- 501-503>505-507-508. WV...WIND ADVISORY UNTIL 8 PM EDT THIS EVENING FOR WVZ050>053-055- 501>506. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT THURSDAY FOR ANZ530>534-537>543. GALE WARNING UNTIL 8 PM EDT THIS EVENING FOR ANZ530>543. SMALL CRAFT ADVISORY FROM 10 AM TO 8 PM EDT THURSDAY FOR ANZ535-536. && $$ SYNOPSIS...GMS NEAR TERM...GMS SHORT TERM...GMS/KRW LONG TERM...DFH AVIATION...GMS/KRW/DFH MARINE...GMS/KRW/DFH TIDES/COASTAL FLOODING...GMS

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