Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 241845 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 245 PM EDT FRI OCT 24 2014 .SYNOPSIS... 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. && .NEAR TERM /THROUGH SATURDAY/...
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&& .SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...
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VERTICALLY STACKED LOW PRESSURE WILL TRAVEL ACROSS SOUTHERN QUEBEC SATURDAY NIGHT...WITH A TRAILING COLD FRONT CROSSING THE LOCAL AREA. THIS FRONT WILL BE VERY WEAK IN NATURE AS THE MOISTURE AND FORCING WITH THIS SYSTEM WILL BE WELL TO OUR NORTH. CONDITIONS MAY BE FAVORABLE FOR UPSLOPE SHOWERS OR SPRINKLES...BUT GIVEN THE SHALLOW NATURE OF THE MOISTURE...WOULD EXPECT ANY AMOUNTS TO BE VERY LIGHT. ANY PRECIPITATION THAT DOES FALL SHOULD BE IN LIQUID FORM AS OVERNIGHT LOWS WILL BE NEAR 40 IN THE HIGHER ELEVATIONS. MUCH IN THE WAY OF CLOUD COVER MAY BE DIFFICULT TO COME BY WITH THE FRONTAL PASSAGE EAST OF THE MOUNTAINS WITH LOWS IN THE UPPER 40S TO LOW 50S. PRESSURE GRADIENT FROM SYSTEM TO THE NORTHEAST WILL RESULT IN A BREEZY SUNDAY WITH GOOD MIXING. MINIMAL THERMAL DIFFERENCES BEHIND THE FRONT...PLENTIFUL SUN AND A DOWNSLOPE FLOW WILL RESULT IN HIGH TEMPERATURES SIMILAR TO SATURDAY ACROSS MOST OF THE AREA...NEAR OR SLIGHTLY ABOVE SEASONAL NORMS. HIGH PRESSURE WILL BUILD INTO THE CENTRAL APPALACHIANS SUNDAY NIGHT AND WITH A DRY ATMOSPHERE... FAVORABLE RADIATIONAL COOLING CONDITIONS WILL DEVELOP. HAVE MID-UPPER 30S WEST OF THE METROS BUT FEEL THESE AREAS COULD SNEAK A FEW DEGREES COOLER. MENTION OF PATCHY FROST HAS BEEN MAINTAINED IN THESE AREAS. MID 40S CAN BE EXPECTED IN THE METROS. THE HIGH WILL SLIDE TOWARD THE CAROLINA COAST ON MONDAY WITH MID/UPPER LEVEL RIDGING EXPANDING TOWARD THE EAST COAST. MANY LOCATIONS WILL SEE HIGHS NEAR OR ABOVE 70.
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&& .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...
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ECMWF INDICATES THAT A SHORTWAVE FROM NORTHERN PLAINS CROSSING GREAT LAKES BY LATE TUESDAY. 500MB TROUGH AND WEAK PVA CROSSING CWA WEDNESDAY. NEXT SHORTWAVE TO CROSS CWA FRIDAY THROUGH SATURDAY. SURFACE FRONT FROM WEST WILL CROSS THE CWA TUESDAY NIGHT INTO THURSDAY MORNING. ANOTHER FRONT FROM THE WEST WILL AFFECT THE CWA FROM LATE THURSDAY INTO FRIDAY AFTERNOON. CERTAINTY REMAINS LOW THIS FAR OUT IN THE FORECAST PERIOD. ALTHOUGH ECMWF TIMING SEEMS TO TRACK FAIRLY WELL WITH HPC ENSEMBLE HPC INDICATES THAT PATTERN WILL PRODUCE LESS PRECIPITATION THAN ECMWF.
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&& .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
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NW WINDS 10-15 KTS G 20KTS EXPECTED THIS AFTERNOON. NW WINDS WILL BECOME NW-W 5-10 KTS TONIGHT AND SATURDAY. VFR CONDITIONS EXPECTED TODAY...TONIGHT AND SATURDAY AS HIGH PRESSURE MOVES OVER THE REGION. CLOUDS WILL INCREASE FROM THE NORTHWEST SAT NIGHT INTO SUNDAY. VFR CONDITIONS EXPECTED. GUSTY NW WINDS ARE EXPECTED SUNDAY.
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&& .MARINE...
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GUSTY NW WINDS WILL CONTINUE ON THE WATERS THIS AFTERNOON AS A PRESSURE GRADIENT PERSISTS OVERHEAD. MIXING WILL SUBSIDE THIS EVENING WITH THE EXCEPTION OF THE LOWER TIDAL POTOMAC AND MD CHESAPEAKE BAY SOUTH OF DRUM PT AS GUSTY WINDS WILL PERSIST THE LONGEST IN THESE SPOTS. A SMALL CRAFT ADVISORY IS IN EFFECT FOR ALL THE WATERS THROUGH THE AFTERNOON AND CONTINUES FOR THE LOWER PORTIONS TONIGHT. HIGH PRESSURE MOVES NEAR THE WATERS TONIGHT AND SATURDAY AND W-NW WINDS ARE EXPECTED BUT WILL STAY BELOW SCA CRITERIA. A DRY COLD FRONT WILL MOVE OVER THE WATERS BY SUNDAY AND NW WINDS WILL INCREASE ACROSS THE WATERS. A SCA IS LIKELY SUNDAY AND 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 UNTIL 6 PM EDT THIS EVENING FOR ANZ530>533-535-536-538>542. SMALL CRAFT ADVISORY UNTIL 2 AM EDT SATURDAY FOR ANZ534-537- 543.
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&& $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...ADS LONG TERM...CEM AVIATION...HAS MARINE...HAS

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