Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 260124 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 924 PM EDT TUE AUG 25 2015 .SYNOPSIS... HIGH PRESSURE OVER THE CENTRAL UNITED STATES WILL SLOWLY MOVE EAST OVER THE NEXT SEVERAL DAYS. IT WILL BECOME CENTERED OVER THE REGION BY FRIDAY AND GENERALLY REMAIN OVER THE REGION INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH WEDNESDAY/...
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HIGH PRESSURE REMAINS CENTERED OVER THE NORTHERN PLAINS THIS EVENING WITH REMNANT FRONT TO OUR SE. PWAT GENERALLY LESS THAN ONE INCH ACROSS THE AREA. ALOFT...CLOSED LOW IS SPINNING ON ONTARIO/QUEBEC BORDER. ONE DISTURBANCE IS LOCATED OVER THE EASTERN CAROLINAS AND WILL SKIRT SE VA TONIGHT...WHILE ANOTHER (WEAKER) ONE IS APPROACHING FROM THE OHIO VALLEY. HRRR AND RAP CONTINUE TO DEVELOP PRECIP BY LATE EVENING IN THE VA PIEDMONT - SOUTHERN MD AREA. EVEN THOUGH THERE IS WEAK THETA-E RIDGE IN THIS AREA...FORECAST SOUNDINGS INDICATED A VERY SHALLOW MOISTURE LAYER AND NO INSTBY/CAPPED PROFILE. THINK SPRINKLES WOULD BE A WORSE CASE SCENARIO...AND THERE WILL BE SOME PATCHES OF CLOUDS AT TIMES. AIR MASS ALSO SEEMS TOO DRY FOR FOG TO BE MUCH OF A CONCERN...ALTHOUGH THERE COULD BE SOME PATCHY LIGHT FOG IN CENTRAL VA/WESTERN VALLEYS ASSUMING SKIES REMAIN CLEAR. TEMPERATURES HAVE TUMBLED QUICKLY WITH SUNSET AND HAVE POTENTIAL TO FALL INTO THE 50S IN MANY AREAS WITH 60S NEAR AND EAST OF I-95. WEATHER FEATURES TRANSLATE SLIGHTLY EASTWARD WEDNESDAY. UPPER LEVEL ENERGY WILL BE PASSING TO THE NORTH...ALONG WITH A JET STREAK OVERHEAD...SO CLOUDS WILL BE A LITTLE MORE PREVALENT WITH NORTHWESTWARD EXTENT. HIGHS ON WEDNESDAY WILL REBOUND TO SIMILAR...PERHAPS SLIGHTLY COOLER...READINGS AND HUMIDITY WILL REMAIN LOW.
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&& .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE WILL REMAIN IN CONTROL THROUGH THE SHORT TERM...ALLOWING FOR DRY WEATHER AND TEMPERATURES A FEW DEGREES BELOW NORMAL. THURSDAY WILL BE THE COOLER OF THE TWO DAYS...AS COOLER AND DRIER AIR CONTINUES TO ADVECT IN FROM THE NORTH AND WEST. WEAK RETURN FLOW BEGINS FRIDAY...WITH A WEAK WARM FRONT LIFTING NORTH THROUGH THE AREA. THIS WILL HELP TO INCREASE TEMPERATURES A FEW DEGREES...THOUGH THEY WILL STILL BE BELOW NORMAL. QUALITY MOISTURE WILL BE LOCATED WELL SOUTH AND EAST...SO DEWPOINTS EXPECTED TO REMAIN AOB 60 EVEN WITH SOUTHERLY FLOW. LACK OF LOW-LEVEL MOISTURE AND/OR LIFTING MECHANISM WILL PRECLUDE SHOWER/THUNDERSTORM DEVELOPMENT DURING THE SHORT TERM. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... HIGH PRESSURE WEAKENS ITS GRIP SLIGHTLY OVER THE WEEKEND...AS WEAK WARM FRONT CONTINUES TO LIFT NORTH THROUGH THE MID-ATLANTIC. SOUTHERLY FLOW CONTINUES...BUT QUALITY LOW-LEVEL MOISTURE WILL STILL REMAIN SOUTH AND EAST OF OUR AREA...WHICH WILL KEEP SFC DEWPOINTS AOB 65. HOWEVER...ENOUGH MOISTURE WILL BE PRESENT OVER THE WEEKEND TO ALLOW FOR A FEW SPOTTY SHOWERS AND ISOLATED STORMS OVER THE HIGHER TERRAIN...WITH SOME SPILLAGE TO THE EAST SUNDAY. LACK OF DECENT LIFT AND MARGINAL INSTABILITY SHOULD KEEP MOST AREAS DRY MOST OF THE TIME. HIGH PRESSURE THEN BEGINS TO REASSERT ITS CONTROL MONDAY INTO TUESDAY. CONTINUED SOUTHERLY FLOW WILL USHER IN SLIGHTLY WARMER TEMPERATURES OVER THE WEEKEND AND INTO EARLY NEXT WEEK...WITH TEMPERATURES A FEW DEGREES ABOVE NORMAL. HOWEVER...HUMIDITY SHOULD REMAIN LOW ENOUGH TO HAVE LITTLE-TO-NO ADDED IMPACT ON HEAT. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
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VFR CONDITIONS EXPECTED THROUGH THE TAF PERIOD AS HIGH PRESSURE SLOWLY BUILDS IN. CIG AOA 5KFT NOT OUT OF THE QUESTION AT TIMES BUT LIKELY WILL NOT PREVAIL. LIGHT WEST TO NORTHWEST WINDS TONIGHT AND WEDNESDAY GENERALLY 10 KNOTS OR LESS. FOG IS NOT EXPECTED TO BE AN ISSUE AT THE TERMINALS TONIGHT. THERE IS A SLIGHTLY HIGHER CHANCE OF BR AT CHO WEDNESDAY NIGHT. OUTLOOK...VFR CONDITIONS WILL CONTINUE TO PREVAIL THROUGH SUNDAY.
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&& .MARINE...
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HIGH PRESSURE REMAINS WELL TO THE WEST TONIGHT AND WEDNESDAY WITH A STALLED FRONT JUST EAST OF THE DELMARVA. A SURGE OF HIGHER PRESSURES WILL PUSH IN FROM THE NORTH TONIGHT AND IT APPEARS THIS WILL INDUCE NORTHERLY CHANNELING ON THE BAY. WITH NUMEROUS GUIDANCE SETS DEPICTING THE POTENTIAL FOR 20 KT WIND GUSTS...HAVE HOISTED A SCA FOR MOST OF THE BAY AND ADJOINING AREAS. WINDS WILL TAPER OFF FROM NORTH TO SOUTH WEDNESDAY MORNING AND WILL REMAIN FROM THE NW OR W THROUGH THE DAY. PRESSURE GRADIENT DOES TIGHTEN UP AGAIN WEDNESDAY NIGHT...SO THERE IS A SMALL CHANCE WINDS COULD BE HIGHER THAN EXPECTED...BUT MIXED LAYER WINDS ARE GENERALLY BELOW 18 KNOTS AND HAVE NOT ISSUED ANYTHING FOR THIS PERIOD. FEW MARINE CONCERNS THROUGH THE EXTENDED UNDER HIGH PRESSURE WITH DRY WEATHER AND LIGHT WINDS. AN ISOLATED SHOWER OR THUNDERSTORM IS POSSIBLE BY LATE SUNDAY...BUT MOST OF THE DAY SHOULD REMAIN DRY.
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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 AM EDT WEDNESDAY FOR ANZ531-532- 539-540. SMALL CRAFT ADVISORY FROM 2 AM TO 11 AM EDT WEDNESDAY FOR ANZ533-534-537-541>543.
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&& $$ SYNOPSIS...RCM NEAR TERM...ADS/RCM SHORT TERM...MSE LONG TERM...MSE AVIATION...ADS/RCM/MSE MARINE...ADS/MSE

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