Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 240736 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 336 AM EDT FRI OCT 24 2014 .SYNOPSIS...
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HIGH PRESSURE WILL BUILD OVERHEAD THROUGH SATURDAY. A REINFORCING COLD FRONT WILL PASS THROUGH THE REGION LATE SATURDAY NIGHT INTO SUNDAY BEFORE HIGH PRESSURE RETURNS FOR MONDAY. THE HIGH WILL MOVE OFF THE COAST DURING THE MIDDLE PORTION OF NEXT WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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AN UPPER LEVEL VORT MAX RIBBON HELPING MIX-DOWN THE GUSTY WINDS ATTM AND WILL CONTINUE HOVERING OVER THE AREA INTO THE POST-DAWN HRS THIS MRNG. OCCASIONAL GUSTS IN THE 20-25KT RANGE...W/ OVERALL SFC WINDS AT A STEADY 10-15KT CLIP OUT OF THE NW. THE EXITING AND SLOW-MOVING UPPER LEVEL SYSTEM FROM A COUPLE OF DAYS AGO STILL HANGING AROUND NEW ENGLAND...E OF THE HUDSON RVR/ERN NY. THE VORT MAX MERELY SWINGING AROUND THE BACKSIDE OF THE UPPER LOW...BEING PULLED ALONG BY THE SYSTEM...NOT EXPECTED TO MAKE MUCH EWD PROGRESS IN THE COMING HRS. FOR THIS REASON...WINDS WILL STAY FAIRLY BREEZY OVERNIGHT WHICH IS NOT ALL THAT COMMON - THEN PICK BACK UP EVEN FURTHER AFTER DAWN. TRAPPED LOW LEVEL MOISTURE ALSO MIXING-DOWN W/ SOME OF THE GUSTS...WHICH IS KEEPING DEWPOINTS RELATIVELY HIGHER THAN W/ A NW FLOW REGIME. EVEN THOUGH SKIES ARE GENERALLY CLEAR ATTM...DEWPOINTS ARE REMAINING RELATIVELY HIGH AND THIS IS KEEPING TEMPS ON THE WARMER SIDE. IF NOT FOR THE MOISTURE...TEMPS WOULD LIKELY BE DROPPING WELL INTO THE 40S AND 30S IN SHELTERED VLYS...BUT MOST SITES ARE BARELY AOB 55F CURRENTLY. NOT QUITE AS GUSTY TODAY AS ON THU BUT TEMPS WILL END UP IN ABOUT AROUND THE SAME LEVELS - M60S...U60S OVER THE SRN TIER COUNTIES. PLENTY OF SUN TODAY...A FEW PASSING UPPER DECKS AS A PRECIP-LESS SHORTWAVE DIGS WELL TO OUR SOUTH...OVER THE SRN APLCNS. THIS FEATURE WILL KEEP ITS INFLUENCES AWAY FROM THE MID-ATLC BUT WILL HELP TO USHER-IN THE MORE CALMING EFFECT OF AN UPPER MIDWEST HIGH. AFTER THE SFC FLOW DISSIPATES POST-SUNSET TONIGHT...DEWPOINTS WILL SLOWLY REBOUND AGAIN INTO THE 40S...FOR ANOTHER REL MILD TEMP RANGE FOR OUR OVERNIGHT LOWS. APPLIED A BIAS-CORRECTED MET/MEX FOR TODAY`S HIGH/LOW TEMP GRIDS. ALSO MODIFIED WINDS IN THE NEAR/SHORT TERMS W/ NEWER HI-RES WRK GUIDANCE.
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&& .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
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THE NOSE OF A POTENT UPPER LEVEL JET WILL MAKE A QUICK ENTRANCE ON SAT...SLAMMING UP AGAINST THE EXITING UPPER LEVEL JET FROM THE OFFSHORE LOW. THIS FAST UPPER NW FLOW WILL START TO BRING IN THE CLOUD COVER TO THE MTNS ON SAT...BUT LEAVE THE REMAINDER OF THE AREA FAIRLY DRY AND CLEAR UNTIL LATER IN THE EVE. BEING ON THE RIGHT-EXIT DOWNWARD MOTION SIDE OF THE UPPER JET WILL KEEP THE AREA DRY HEADING INTO THE WEEKEND. WEAK BUT STEADY DOWNSLOPING FLOW MAY HELP BRING TEMPS UP A FEW MORE DEG...PEAKING IN THE M-U60S - POSSIBLY JUST ABOVE 70F FOR SAT AFTN. LOW PRESSURE WILL TRACK THROUGH EASTERN CANADA SATURDAY NIGHT AND EVENTUALLY TOWARD NOVA SCOTIA ON SUNDAY. THE COLD FRONT ASSOCIATED WITH THIS SYSTEM WILL PASS THROUGH OUR REGION LATE SATURDAY NIGHT INTO SUNDAY. LITTLE FORCING AND LITTLE MOISTURE WILL BE ASSOCIATED WITH THE FRONT. THEREFORE...MOST AREAS WILL REMAIN DRY WITH JUST A FEW CLOUDS NEAR THE BOUNDARY. THERE MAY BE A FEW SHOWERS ALONG AND WEST OF THE ALLEGHENY FRONT DUE TO AN UPSLOPE FLOW...BUT EVEN ACROSS THESE AREAS ANY PRECIPITATION WILL BE LIGHT. LEANED TOWARD THE WARMER GUIDANCE SATURDAY NIGHT DUE TO SOME CLOUD COVER AND A GRADIENT WIND HOLDING OFF ANY RADIATIONAL COOLING. MIN TEMPS ARE FORECAST TO RANGE FROM NEAR 40 ALONG THE RIDGE TOPS OF THE POTOMAC HIGHLANDS TO THE LOWER AND MIDDLE 50S IN DOWNTOWN WASHINGTON AND BALTIMORE. HIGH PRESSURE WILL APPROACH THE REGION SUNDAY BEHIND THE COLD FRONT...BUT THE GRADIENT WILL REMAIN STRONG BETWEEN THE APPROACHING HIGH AND THE DEPARTING COLD FRONT...RESULTING IN BREEZY CONDITIONS. NORTHWEST WINDS WILL GUST AROUND 20 TO 30 MPH DURING THE LATE MORNING AND AFTERNOON HOURS. SUNSHINE AND A DOWNSLOPING FLOW WILL OFFSET ANY WEAK COLD AIR ADVECTION...ALLOWING FOR MAX TEMPS TO BE ABOVE CLIMO. OF COURSE...THE MILD CONDITIONS MAY BE OFFSET BY THE GUSTY WINDS. LEANED TOWARD THE WARMER SIDE OF GUIDANCE...WITH MAX TEMPS FORECAST TO RANGE FROM THE 50S IN THE MOUNTAINS TO THE MIDDLE 70S ACROSS CENTRAL VIRGINIA INTO SOUTHERN MARYLAND. HIGH PRESSURE WILL BUILD OVERHEAD SUNDAY NIGHT...CAUSING WINDS TO DIMINISH. LIGHT WINDS...MAINLY CLEAR SKIES AND DRY CONDITIONS WILL PROVIDE A GOOD SETUP FOR RADIATIONAL COOLING. THEREFORE...MIN TEMPS SUNDAY NIGHT WILL BE CHILLY...RANGING FROM THE MIDDLE 30S ACROSS NORTHERN MARYLAND AND FOR LOCATIONS NEAR AND WEST OF THE BLUE RIDGE MOUNTAINS...TO THE MIDDLE 40S IN DOWNTOWN WASHINGTON AND BALTIMORE. FROST IS POSSIBLE ACROSS MANY LOCATIONS OVERNIGHT SUNDAY. .LONG TERM /MONDAY THROUGH THURSDAY/... HIGH PRESSURE WILL MOVE OFF THE COAST MONDAY AND TUESDAY. A SOUTHERLY WIND WILL ALLOW FOR MILDER CONDITIONS DURING THIS TIME. A COLD FRONT WILL PASS THROUGH THE AREA TUESDAY NIGHT INTO WEDNESDAY...AND IT WILL STALL OUT NEARBY FOR LATER WEDNESDAY AND THURSDAY. UNSETTLED CONDITIONS ARE POSSIBLE DURING THIS TIME...BUT CERTAINTY REMAINS LOW THIS FAR OUT IN THE FORECAST PERIOD.
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&& .AVIATION /07Z FRIDAY THROUGH TUESDAY/...
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ANOTHER BREEZY AFTN TODAY BUT A TIER LOWER IN TERMS OF PEAK GUSTS...WHERE 15-20KT WILL BE FAIRLY COMMON FROM AFTER SUNRISE. SEVERAL MORE HEADING INTO THE DAYTIME HRS...OF THE STEADY BREEZE TODAY. WINDS WILL THEN QUICKLY DROP OFF TOWARD SUNSET. HIGH PRESSURE CONTINUE STRENGTHENING OVER THE AREA INTO SAT. NORTHWEST WINDS WILL GUST AROUND 20 TO 25 KNOTS SUNDAY. WINDS WILL DIMINISH AROUND SUNSET SUNDAY EVENING...AND LIGHT WINDS ARE EXPECTED OVERNIGHT AS HIGH PRESSURE BUILDS OVERHEAD. SOUTH- SOUTHWEST WINDS ARE EXPECTED MONDAY AND TUESDAY AS HIGH PRESSURE MOVES OFF THE COAST. VFR CONDITIONS ARE EXPECTED SUNDAY THROUGH TUESDAY.
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&& .MARINE...
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A WEAK UPPER LOW WILL MEANDER JUST OFF THE COAST INTO THE LATE NIGHT HRS TONIGHT BUT TAKE IT`S BREEZY INFLUENCE. SCA CONTINUED FOR ALL THE WATER THIS AFTN. MAY NEED TO FURTHER EXPAND THE SCA FOR THE LOWEST BAY ZONES BUT WILL MONITOR UPCOMING SCA POTENTIAL. A REINFORCING COLD FRONT WILL PASS THROUGH THE WATERS LATE SATURDAY NIGHT INTO SUNDAY. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS SATURDAY NIGHT. A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED FOR NORTHWEST WINDS BEHIND THE FRONT SUNDAY INTO SUNDAY NIGHT. HIGH PRESSURE WILL BUILD OVERHEAD LATE SUNDAY NIGHT INTO MONDAY BEFORE MOVING OFF THE COAST LATER MONDAY THROUGH THE MIDDLE PORTION OF NEXT WEEK. A SOUTHERLY FLOW WILL INCREASE DURING THIS TIME. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS TUESDAY AND WEDNESDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 9 AM THIS MORNING TO 6 PM EDT THIS EVENING FOR ANZ530-531-535-536-538>540-542. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ532>534-537-541-543.
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&& $$ SYNOPSIS...BJL NEAR TERM...GMS SHORT TERM...BJL/GMS LONG TERM...BJL AVIATION...BJL/GMS MARINE...BJL/GMS

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