Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 071443 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1043 AM EDT TUE JUL 7 2015 .SYNOPSIS... HIGH PRESSURE WILL DOMINATE TODAY INTO THE FIRST PART OF TONIGHT. A COLD FRONT WILL MOVE IN FROM THE GREAT LAKES ON WEDNESDAY. THE FRONT WILL SLIDE SLOWLY SOUTH ACROSS THE AREA THURSDAY AND FRIDAY BEFORE SLOWLY MOVING BACK NORTH OVER THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY/... REGION REMAINS POSITIONED BETWEEN HIGH PRESSURE OFFSHORE AND AN APPROACHING COLD FRONT CURRENTLY NOTED OVER IL/IN VIA LATEST IR SAT. SUBSIDENCE BUILDING IN ALOFT WILL LEAD TO CLEARING SKIES THRU EARLY AFTN. WAA RIDING ON THE SWLY FLOW WILL PUSH 850MB TEMPS TO NEAR 19 DEGREES CELSIUS TODAY...RESULTING IN WIDESPREAD 90S...80S OVER HIGHER ELEVATIONS. AFTN CU WILL FORM WITH AFTN WARMING...BUT DRIER AIR ALOFT WILL MINIMIZE FURTHER VERTICAL PROGRESSION. THIS COMBINED WITH NO REAL SFC BOUNDARY SHOULD KEEP MOST OF THE AREA DRY TODAY. THE COLD FRONT WILL APPROACH THE WESTERN AREAS LATER TONIGHT AND MOVE THROUGH THE REGION ON WEDNESDAY. SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS WILL BE POSSIBLE BY THIS EVENING OVER THE POTOMAC HIGHLANDS WITH COVERAGE INCREASING FROM WEST TO EAST ON WEDNESDAY. HAVE INCREASED POPS TO CATEGORICAL DURING THE DAY. NOT EXPECTING SEVERE WEATHER AT THIS TIME AND WILL LEAVE MENTION OUT OF THE HAZARDOUS WEATHER OUTLOOK. && .SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY NIGHT/... MAIN PRECIP ASSOCIATED WITH WEAK COLD FRONT SHOULD BE ENDING BY THU MORNING...WITH ONLY LINGERING SHOWERY ACTIVITY REMAINING...IF ANY. LOW CHCS FOR PRECIP DURING THE DAY THU...AS COLD FRONT WILL BE TO OUR SOUTH AND WE ARE LIKELY UNDER SUBSIDENCE FROM DEPARTING MID/UPPER LEVEL WAVE. DIFFICULT TO FIND ANY INSTABILITY THU AFTERNOON...BUT CANNOT RULE OUT A DIURNALLY DRIVEN ISOLATED SHWR/TSTM ALONG/NEAR ANY NEBULOUS FORCING MECHANISMS. TEMPS NEAR CLIMO NORMS WITH M/U 80S IN CWA. WEAK COLD FRONT WILL ONLY TEMPORARILY REDUCE DEWPOINTS...AS BY AFTERNOON THEY WILL RETURN TO THE U60S...WHICH WILL KEEP HEAT INDICES IN THE M90S. SECONDARY COLD FRONT...ASSOCIATED WITH LP MOVING ACROSS OHIO VALLEY...APPEARS TO SLIDE THROUGH THE AREA LATE THU. AT THIS POINT...POOR TIMING ALONG WITH LIMITED MOISTURE AND INSTABILITY AHEAD OF THE FRONT...WOULD KEEP PRECIP CHCS FAIRLY LOW. BETTER MOISTURE/TEMP GRADIENT ALONG FRONT...SO EXPECT TEMPS AND DEWPOINTS TO DROP FURTHER BEHIND THIS SECONDARY SURGE. FRI HIGHS SHOULD BE IN L/M 80S...OR A FEW DEGREES BELOW NORMAL. && .LONG TERM /SATURDAY THROUGH MONDAY/... QUASI-ZONAL MID/UPPER FLOW PATTERN OF MID-WEEK TRANSITIONS TO NW FLOW PATTERN THROUGH THE EXTENDED...AS RIDGING BECOMES ESTABLISHED OVER THE SE STATES. OUR AREA REMAINS ALONG THE PERIPHERY OF THE RIDGE/ NEAR RING OF FIRE/ WHICH WILL KEEP CHCS FOR UNSETTLED WEATHER THROUGH THE PERIOD...DESPITE ANY CLEAR FORCING MECHANISMS. WARM FRONT LOOKS TO LIFT BACK NORTH THROUGH THE REGION OVER THE WEEKEND...WHICH WILL HELP TO INCREASE TEMPERATURES BY SUN BACK INTO THE U80S...DESPITE THE NW FLOW. BEST CHCS FOR PRECIP APPEAR MON AS RIDGING SLIDES FURTHER WEST OVER SOUTHERN PLAINS AND SW TROUGH DROPS INTO THE AREA. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... VFR CONDITIONS FOR THE TAF PERIOD. INCRSG PCPN TONIGHT INTO WED...WITH ANY SHOWER/TSTM RESULTING IN PSBL SUB-VFR CONDITIONS. SW WINDS TODAY 8-10 KTS...WITH PSBL OCNL GUSTS TO 20 KTS THIS AFTN. VFR CONDS EXPECTED FOR THE REMAINDER OF THE WEEK OUTSIDE OF ANY SHWR/TSTM ACTIVITY. LOCALIZED SUB-VFR CONDS ARE PSBL DUE TO SHWRS/TSTMS...THOUGH CHCS FOR TSTMS ARE LOW EACH DAY WITH NEBULOUS FORCING. && .MARINE... PERIODIC SCA CONDITIONS ESPECIALLY OVER THE SOUTHERN WATERS AHEAD OF A COLD FRONT THIS EVENING. WINDS BELOW SCA EXPECTED ON WEDNESDAY. SHOWERS AND THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND HEAVY RAINFALL ON WEDNESDAY. WINDS EXPECTED TO REMAIN BELOW SCA CRITERIA THROUGH THE EXTENDED. LOW CHCS FOR TSTMS OVER THE WATERS ARE FORECAST EACH DAY THROUGH THE EXTENDED. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 8 AM EDT WEDNESDAY FOR ANZ533-534-537-541>543. && $$ SYNOPSIS...KRW NEAR TERM...SEARS/KRW SHORT TERM...MSE LONG TERM...MSE AVIATION...SEARS/MSE/KRW MARINE...MSE/KRW

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