Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 270734 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 334 AM EDT MON OCT 27 2014 .SYNOPSIS...
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HIGH PRESSURE WILL MOVE OFF TO THE EAST TODAY THROUGH TUESDAY. A COLD FRONT WILL PASS THROUGH THE AREA WEDNESDAY AND HIGH PRESSURE WILL RETURN FOR THURSDAY AND FRIDAY. ANOTHER COLD FRONT WILL PASS THROUGH THE AREA FRIDAY NIGHT AND CANADIAN HIGH PRESSURE WILL BUILD OVERHEAD DURING THE WEEKEND.
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&& .NEAR TERM /THROUGH TONIGHT/...
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SURFACE HIGH PRESSURE WILL CONTINUE TO BUILD OVER THE REGION EARLY THIS MORNING. THE ATMOSPHERE HAS DECOUPLED ACROSS MOST AREAS...WHICH HAS ALLOWED FOR RADIATIONAL COOLING TO SET UP. A FROST ADVISORY IS IN EFFECT FOR THE SHENANDOAH VALLEY AS WELL AS PORTIONS OF NORTHERN AND CENTRAL VIRGINIA...CENTRAL MARYLAND AND THE NORTHERN AND WESTERN SUBURBS OF WASHINGTON/BALTIMORE. THE HIGH WILL MOVE OFF TO THE EAST TODAY AND A SOUTHERLY FLOW WILL DEVELOP. THE SOUTHERLY FLOW WILL ALLOW FOR MILD CONDITIONS THIS AFTERNOON. LEANED TOWARD THE WARMER MAV MOS SINCE THERE WILL BE PLENTY OF SUNSHINE AND A RELATIVELY DEEP MIXING LAYER. MAX TEMPS ARE FORECAST TO RANGE FROM THE MID TO UPPER 60S IN NORTHEASTERN MARYLAND TO THE MIDDLE 70S IN CENTRAL VIRGINIA. A LIGHT SOUTHERLY FLOW IS EXPECTED TONIGHT...WHICH WILL ALLOW FOR MILDER CONDITIONS COMPARED TO EARLY THIS MORNING. MIN TEMPS ARE FORECAST TO RANGE FROM THE LOWER TO MIDDLE 40S IN MANY VALLEY LOCATIONS AS WELL AS THE NORTHERN AND WESTERN SUBURBS OF WASHINGTON/BALTIMORE TO THE MIDDLE 50S IN DOWNTOWN WASHINGTON AND BALTIMORE.
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&& .SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
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HIGH PRESSURE WILL REMAIN OVER THE ATLANTIC TUESDAY WHILE A COLD FRONT APPROACHES FROM THE WEST. THE FRONT SHOULD REMAIN FAR ENOUGH TO OUR WEST FOR MORE SUNSHINE AND DRY CONDITIONS. A SOUTHERLY FLOW WILL INCREASE BETWEEN THE HIGH TO OUR EAST AND THE COLD FRONT TO OUR WEST...AND THIS COMBINED WITH PLENTY OF SUNSHINE WILL ALLOW FOR WARM CONDITIONS FOR THIS TIME OF YEAR. LEANED TOWARD THE WARMER GUIDANCE...WITH MAX TEMPS FORECAST TO RANGE FROM THE LOWER 70S ALONG THE MARYLAND CHESAPEAKE BAY TO THE UPPER 70S AND LOWER 80S ACROSS MOST OTHER LOCATIONS. THE COLD FRONT WILL MOVE INTO WESTERN PORTIONS OF THE CWA TUESDAY NIGHT BEFORE SLOWLY PASSING THROUGH WEDNESDAY. EXACT TIMING OF THE FRONTAL PASSAGE IS UNCERTAIN...BUT THERE WILL BE MORE CLOUDS ALONG WITH THE CHANCE FOR SHOWERS STARTING LATE TUESDAY NIGHT ACROSS THE WESTERN PORTIONS OF THE CWA AND EVENTUALLY SPREADING INTO THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS AS WELL AS SOUTHERN MARYLAND WEDNESDAY. ANY LEFTOVER SHOWERS ACROSS THE EASTERN AREAS WEDNESDAY EVENING WILL DISSIPATE AS THE FRONT MOVES OFF TO THE EAST AND HIGH PRESSURE BUILDS OVERHEAD. DRY AND SEASONABLY CHILLY CONDITIONS ARE EXPECTED OVERNIGHT WEDNESDAY.
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&& .LONG TERM /THURSDAY THROUGH SUNDAY/...
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DECENT AGREEMENT BETWEEN ECMWF AND GFS THROUGH THE LONG TERM PERIOD ON THE SYNOPTIC SETUP. AMPLIFIED UPPER LEVEL PATTERN WILL BE IN PLACE...WITH GENERALLY RIDGING OVER THE ROCKIES AND TROUGHING OVER THE EASTERN CONUS. PATTERN BEGINS TO SHIFT EASTWARD TOWARD THE WEEKEND AS A TROUGH PUSHES ONTO WEST COAST. SURFACE HIGH PRESSURE WILL BUILD IN FROM THE WEST ON THURSDAY. EXPECT TEMPERATURES TO FALL BELOW CLIMO BEHIND THE DEPARTING COLD FRONT. FRIDAY INTO SATURDAY...ENERGY DIGS SOUTHEASTWARD FROM THE GREAT LAKES AND FORMS A CLOSED LOW OVER NEW ENGLAND. SURFACE COLD FRONT WILL LIKELY PUSH THROUGH FRIDAY EVENING BUT WILL LACK MOISTURE. POSSIBLY THE COOLEST AIR OF THE SEASON IS ON TAP FOR SATURDAY INTO SATURDAY NIGHT. CURRENT PROJECTIONS INDICATE ONLY 40S FOR HIGHS AND NEAR OR BELOW FREEZING WEST OF I-95 ON SATURDAY NIGHT. THIS WILL ALSO BE A BREEZY PERIOD FOR THE NORTHERN/EASTERN SECTIONS AS THE LOW WINDS UP ALONG THE NEW ENGLAND COAST. HIGH PRESSURE WILL BEGIN TO BUILD IN FROM THE WEST ON SUNDAY AS TEMPERATURES ONLY MODERATE SLIGHTLY.
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&& .AVIATION /07Z MONDAY THROUGH FRIDAY/...
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VFR CONDITIONS ARE EXPECTED MOST OF THE TIME THROUGH FRIDAY. WINDS WILL TURN TO THE SOUTH TODAY WITH SPEEDS AROUND 5 TO 10 KNOTS THIS AFTERNOON. WINDS WILL BE LIGHT TONIGHT...BUT SPEEDS WILL INCREASE FROM THE SOUTH TUESDAY WITH GUSTS AROUND 15 TO 20 KNOTS EXPECTED. A COLD FRONT WILL PASS THROUGH THE TERMINALS LATE TUESDAY NIGHT AND WEDNESDAY...BRINGING MORE CLOUDS ALONG WITH THE CHANCE FOR SHOWERS. CIGS/VSBYS MAY APPROACH MVFR LEVELS DURING THIS TIME. HIGH PRESSURE WILL RETURN FOR LATE IN THE WEEK.
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&& .MARINE...
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HIGH PRESSURE WILL MOVE OFF THE COAST TODAY AND WINDS WILL TURN TOWARD THE SOUTH...BUT SPEEDS WILL REMAIN BELOW SCA CRITERIA. SOUTHERLY WINDS WILL INCREASE TONIGHT ACROSS THE MARYLAND CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER...BUT SPEEDS HAVE BEEN CAPPED AT 15 KNOTS FOR NOW SINCE THE GRADIENT WILL BE RELATIVELY WEEK. SOUTH TO SOUTHWEST WINDS WILL INCREASE TUESDAY AHEAD OF AN APPROACHING COLD FRONT. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE WATERS. THE COLD FRONT WILL CONTINUE TO APPROACH THE WATERS TUESDAY NIGHT BEFORE PASSING THROUGH WEDNESDAY. HIGH PRESSURE WILL RETURN FOR LATE IN THE WEEK. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS AHEAD OF THE FRONT TUESDAY NIGHT...AND AGAIN WITH A PRESSURE SURGE BEHIND THE FRONT LATE WEDNESDAY NIGHT INTO THURSDAY.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR MDZ003>005-009- 010. VA...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ025>031- 036>040-042-050>053-055-056-501-502. WV...FROST ADVISORY UNTIL 9 AM EDT THIS MORNING FOR WVZ051>053. MARINE...SMALL CRAFT ADVISORY FROM 6 AM TO 6 PM EDT TUESDAY FOR ANZ532>534-537-540-541-543. SMALL CRAFT ADVISORY FROM 10 AM TO 6 PM EDT TUESDAY FOR ANZ530- 531-535-536-538-539-542.
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&& $$ SYNOPSIS...BJL NEAR TERM...BJL SHORT TERM...BJL LONG TERM...ADS AVIATION...BJL MARINE...BJL

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