Area Forecast Discussion
Issued by NWS Wakefield, VA

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000 FXUS61 KAKQ 180809 AFDAKQ AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 409 AM EDT SAT OCT 18 2014 .SYNOPSIS... DRY COLD FRONT CROSSES THE REGION TODAY. COOL CANADIAN HIGH PRESSURE BUILDS IN FROM THE NORTHEAST SATURDAY NIGHT AND SUNDAY...LOCATING OVER THE REGION THROUGH MONDAY. LOW PRESSURE MOVES INTO THE REGION MONDAY NIGHT AND TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... QUIET WEATHER OVER THE REGION THIS MORNING IN ADVANCE OF A COLD FRONT LOCATED OVER THE CNTRL APPALACHIANS. WHILE SKIES ARE CLEAR...MIXING FROM SW WINDS OF 5-10 MPH HAS HELPED KEEP TEMPS IN THE MID TO UPPER 50S INLAND TO LOW 60S NEAR THE COAST. TEMPS WILL DROP ONLY A FEW DEGS...IF AT ALL...THIS MORNING. COLD FRONT WILL CROSS THE LOCAL AREA LATE THIS MORNING THRU THE AFTERNOON AS THE ASSOCIATED UPPER SHORTWAVE LIFTS INTO SE CANADA. MEANWHILE...MORE POTENT SHORTWAVE DIGS OVER THE GREAT LAKES REGION INTO THE OH VALLEY. A COOL/DRY AIR MASS WILL ADVECT INTO THE REGION POST FRONTAL AS WINDS BECOME W-NW THIS AFTERNOON. THICKNESSES PLUMMET 50 TO 60 METERS TODAY AND TONIGHT WITH HIGHS OCCURRING JUST IN ADVANCE OF THE FRONT. TEMPS WARM INTO THE THE UPPER 60S NW TO UPPER 70S SE. TEMPS WILL FALL MID-LATE AFTERNOON EXCEPT IN THE FAR SE. UPSTREAM DEW POINTS ARE GENERALLY IN THE LOW 40S...WHICH WILL ADVECT INTO THE REGION THIS AFTERNOON AND TONIGHT. EXPECT A FEW GUSTS OF 25 MPH OVER THE ERN SHORE THIS AFTERNOON. MID-UPPER CLOUDS WILL INCREASE FROM THE WEST LATE TODAY AND TONIGHT AS THE AFOREMENTIONED POTENT SHORTWAVE DROPS OVER THE MID-ATLANTIC TONIGHT. MOISTURE STILL REMAINS LIMITED...BUT THE STRENGTH OF THE UPPER VORT AND THE PRESENCE OF MODEST LOW-LEVEL MOISTURE MAY BE ENOUGH FOR SPRINKLES...MAINLY OVER THE N AND NE...BUT NOT ENOUGH TO MENTION POPS OVERNIGHT. BEST CHANCES FOR MEASURABLE PRECIP WILL REMAIN OFFSHORE...CLOSEST TO THE BEST MOISTURE SOURCE. NEWLY WINDS 5-10 KT AND PARTLY CLOUDY-MOSTLY CLOUDY SKIES WILL RESULT IN LOW TEMPS IN THE LOW-MID 40S INLAND AND UPPER 40S TO LOW 50S NEAR THE COAST. && .SHORT TERM /SUNDAY THROUGH MONDAY/... SHORTWAVE PUSHES OFFSHORE SUN MORNING AS COOL CANADIAN HIGH PRESSURE SURGES INTO THE REGION. CA WANES SUN...BUT NW FLOW ALOFT AND HIGH PRESSURE BUILDING IN WILL RESULT IN A COOL DAY SUNDAY. HEIGHTS/THICKNESSES YIELD TEMPS IN THE LOW-MID 60S...NEARLY 1 STD DEV BELOW NORMAL. UPPER/SFC HIGH PRESSURE WILL RESULT IN DRY CONDITIONS AND MOSTLY SUNNY-PARTLY CLOUDY SKIES. THE HIGH CENTERS OVER THE LOCAL AREA SUN NIGHT...AS THE BL STABILIZES AND WINDS BECOME CALM-LIGHT. IDEAL RADIATIONAL COOLING AND DEW POINTS DROPPING INTO THE LOW 30S WILL RESULT IN THE COLDEST TEMPS OF THE SEASON THUS FAR...DROPPING INTO THE MID 30S INLAND. TEMPS ALONG THE IMMEDIATE COAST WILL DROP ONLY INTO THE LOW-MID 40S. HIGH PRESSURE PUSHES OFFSHORE MONDAY AS FLOW RETURNS TO THE SOUTH. RESULTANT WEAK WAA AND MODEST HEIGHT RISES YIELD SLIGHTLY MILDER TEMPS MONDAY...WITH HIGHS IN THE MID-UPPER 60S UNDER PARTLY CLOUDY SKIES. THE NEXT STORM SYSTEMS DIGS OVER THE GREAT LAKES REGION INTO THE OH VALLEY MONDAY AS THE ASSOCIATED COLD FRONT APPROACHES THE REGION. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... AN UPPER TROUGH IS EXPECTED TO DIG THROUGH THE OHIO VALLEY MONDAY NIGHT AND TUESDAY AS LOW PRESSURE DEVELOPS IN VICINITY OF THE GULF STREAM. THE TREND AMONGST 17/12Z NUMERICAL GUIDANCE IS FOR THE TROUGH TO CLOSE OFF AND SLOWLY TRAVERSE THE MID-ATLANTIC REGION WEDNESDAY INTO THURSDAY WITH SURFACE LOW PRESSURE LIFTING NNE OFF THE COAST. POPS HAVE ACCORDINGLY BEEN ADJUSTED TO REFLECT A 25-40% CHC OF SHOWERS TUES/WED...TAPERING TO 20% THURSDAY AS HIGHEST CHANCES WILL BE OVER THE EASTERN SHORE/COASTAL WATERS. THE PRESENCE OF THE UPPER SYSTEM AND LOW-LEVEL NORTHERLY FLOW (BY WED/THU) SHOULD RESULT IN CONSIDERABLE CLOUD COVER AND COOLER TEMPERATURES. HIGHS TUESDAY ARE FORECAST TO RANGE FROM THE LOW 60S NW...TO AROUND 70 SE...FOLLOWED BY MID 50S NW TO LOW/MID 60S SE WEDNESDAY AND THURSDAY. OVERNIGHT LOWS SHOULD AVERAGE IN THE MID 40S TO LOW 50S. THE UPPER LOW QUICKLY LIFTS INTO NEW ENGLAND NEXT FRIDAY FOR DRY WX. FRIDAY`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