Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 180601 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 201 AM EDT SAT OCT 18 2014 .SYNOPSIS...
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A COLD FRONT WILL CROSS THE MID-ATLANTIC SATURDAY. AN UPPER LEVEL CUT OFF LOW WILL LIKELY AFFECT THE REGION FOR MUCH OF THE COMING WEEK.
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&& .NEAR TERM /THROUGH SATURDAY NIGHT/...
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DRY CONDITIONS ACROSS THE REGION ATTM. MID-LEVEL CLOUDS ARE MOVING INTO THE REGION AHEAD OF A COLD FRONT OVER WV. THESE CLOUDS WILL CONTINUE TO GRADUALLY INCREASE OVER THE FORECAST AREA IN THE EARLY MORNING HOURS. DELAYED ONSET OF UPSLOPE PRECIPITATION OVER THE HIGHLANDS DUE TO TIMING OF THE FRONTAL PASSAGE AND WIND SHIFT TO THE W-WNW. FCST MIN TEMPS WILL RANGE FROM THE 40S IN THE HIGHLANDS TO UPPER 50S IN THE CITY CENTERS. FLOW ALOFT BECOMES MORE ZONAL AS A COLD FRONT MOVES ACROSS THE REGION SATURDAY MORNING. A STRATO-CU FIELD IS EXPECTED AND WILL LIKELY BE MORE WIDESPREAD THAN TODAY...FRIDAY. AN ISOLATED RAIN SHOWER IS POSSIBLE ACROSS THE POTOMAC HIGHLANDS AND NORTHERN VA SATURDAY AFTERNOON. W-NW WINDS ARE ALSO EXPECTED SATURDAY AND GUSTS UP TO 30 MPH ARE POSSIBLE SAT AFTERNOON. HIGH PRESSURE WILL MOVE INTO THE REGION SATURDAY NIGHT AS ANOTHER SHORTWAVE TROUGH MOVES OVERHEAD. AT THIS TIME...MODELS ARE SHOWING LITTLE TO NO RAIN WITH THIS FEATURE AS COLD AIR ADVECTION OCCURS THROUGHOUT THE COLUMN. SHOWERS ARE LIKELY IN THE UPSLOPE REGION AS NW FLOW MOVES UP AGAINST THE ALLEGHENY FRONT SAT NIGHT. TEMPS WILL LIKELY DROP INTO THE 30S IN THIS REGION BY SUN MORNING. SHOWERS ARE EXPECTED TO TAPER OFF BUT BEFORE THEY DO SOME SNOWFLAKES MAY MIX IN BEFORE SUNRISE SUNDAY MORNING.
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&& .SHORT TERM /SUNDAY THROUGH MONDAY/... HIGH PRESSURE MOVES OVERHEAD SUNDAY AS A UPPER LEVEL RIDGE APPROACHES FROM THE WEST. SUNDAY WILL FEEL COOL WITH MAX TEMPS ONLY REACHING THE UPPER 40S IN THE HIGHLANDS AND UPPER 50S NEAR 60 ACROSS THE PIEDMONT AND SOUTHERN MD. HIGH PRESSURE WILL MOVE OFF THE COAST MONDAY AND SOUTHERLY FLOW WILL HELP TEMPS WARM BY A FEW MORE DEGREES THAN SUNDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... ECMWF 500MB TROUGH MOVING EAST ACROSS THE MIDWEST THROUGH EARLY HALF OF THE WEEK. SHORTWAVES DIGGING DOWN TROUGH ALSO CAUSING IT TO DEEPEN DURING THE PERIOD. CUT-OFF LOW FORMING OVER UPPER OHIO VALLEY AT MID WEEK WILL CROSS MID ATLANTIC REGION DURING THE LATTER HALF OF THE WEEK. TRACK OF SURFACE LOW IS LIKELY TO PERMIT GREATEST OF OPPORTUNITY OF PRECIPITATION TO OCCUR OVER CWA TUESDAY NIGHT THROUGH WEDNESDAY AND AGAIN THURSDAY. INCREASING WINDS EXPECTED WEDNESDAY THROUGH FRIDAY AS PRESSURE GRADIENT TIGHTENING UP WHEN LOW PUSHES OFFSHORE AND SLOWLY MOVES NORTHEASTWARD. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
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VFR CONDS THROUGH SATURDAY NIGHT. WINDS BECOME W-NW SATURDAY AT 10-15KTS WITH GUSTS UP TO 20 KTS BY AFTERNOON. OCCASIONAL GUSTS TO 25KT WILL BE POSSIBLE. SOUNDINGS FOR SATURDAY NIGHT HINT AT POSSIBLE MVFR CIGS...BUT CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN TAFS AT THIS TIME. GUSTS WILL DIMINISH IN THE EVENING. W-NW BREEZY WINDS WILL CONTINUE INTO SUNDAY WITH GUSTS UP TO 25 KTS POSSIBLE SUN AFTERNOON. MAINLY DRY INTO EARLY NEXT WEEK...THOUGH ANOTHER SLOW-MOVING LOW PRESSURE SYSTEM MAY AFFECT THE REGION DURING THE MIDDLE PART OF NEXT WEEK. NOT NEARLY AS MUCH PRECIP TO CONTEND W/ AS THE EXITING FEATURE BUT MAY SEE PERIODICALLY LOWER CIGS AND SOME SCATTERED SHOWERS.
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&& .MARINE...
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FORECAST ON TRACK AT THE MOMENT...WITH GUSTS TO NEAR 20KT NOTED IN OBSERVATIONS ALONG PORTIONS OF THE CHES BAY AND LOWER TIDAL POTOMAC WHERE A SMALL CRAFT ADVISORY IS IN EFFECT. THE SCA EXPANDS TO ALL WATERS AT 14Z SAT MORNING...WHEN A DRY COLD FRONT WILL CROSS THE WATERS AND W-NW WILL INCREASE BEHIND IT. GUSTS UP TO 25 KTS ARE EXPECTED ON THE WATERS SATURDAY. SCA HAS BEEN EXTENDED THROUGH SAT NIGHT FOR CHES BAY SOUTH OF SANDY POINT AND THE LOWER TIDAL POTOMAC RIVER. THESE WINDS MAY CONTINUE ON THE WATERS THROUGH SUNDAY AND A SCA WILL LIKELY NEED TO BE EXPANDED FOR ALL THE WATERS ON SUN AFTN W/ ANOTHER UPPER WAVE MIXING DOWN GUSTY WINDS. HIGH PRESSURE EXPECTED TO BUILD IN BEHIND THIS WAVE TO START THE WORK WEEK.
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&& .TIDES/COASTAL FLOODING...
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05Z OB AT ANNAPOLIS AT 2.21 FEET. HIGH TIDE WILL BE REACHED WITHIN THE HOUR...AND THE WATER LEVEL SHOULD STAY SHORT OF MINOR FLOODING. DEPARTURES ARE EXPECTED TO DECREASE SATURDAY UNDER WESTERLY WINDS.
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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 10 AM THIS MORNING TO 8 PM EDT THIS EVENING FOR ANZ530-531-535-536-538-539. SMALL CRAFT ADVISORY UNTIL 6 AM EDT SUNDAY FOR ANZ532>534-537- 540>543.
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&& $$ SYNOPSIS...KCS NEAR TERM...KCS SHORT TERM...HAS LONG TERM...CEM AVIATION...KCS/HAS MARINE...KCS/HAS TIDES/COASTAL FLOODING...KCS

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