Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 231851 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 251 PM EDT WED JUL 23 2014 .SYNOPSIS... A COLD FRONT FROM THE GREAT LAKES WILL SLOWLY APPROACH THE REGION THROUGH TONIGHT. THE BOUNDARY WILL SLOWLY PASS THROUGH THE AREA THURSDAY INTO THURSDAY NIGHT AND HIGH PRESSURE WILL RETURN FOR FRIDAY. HIGH PRESSURE WILL MOVE OFF THE COAST DURING THE WEEKEND AND A COLD FRONT WILL PASS THROUGH THE AREA EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/...
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CYCLONIC FLOW ALOFT CONTINUES AS A UPPER LEVEL TROUGH PERSISTS ACROSS THE NORTHEASTERN U.S. A BERMUDA HIGH PERSISTS TO THE EAST WHILE A COLD FRONT APPROACHES THE POTOMAC HIGHLANDS THIS AFTERNOON. HOT AND HUMID CONDITIONS HAVE LED TO INSTABILITY ON THE ORDER OF 2K-3K J/KG. A CU FIELD HAS DEVELOPED IN AREAS THAT HAVE SEEN FULL SUNSHINE TODAY. AREAS THAT ARE CLEAR SAW CLOUDS THIS MORNING AND HAVE NOT YET REACHED THEIR CONVECTIVE TEMP. ALL SHOULD BE FILLED IN WITH CU SOON. FCST MAX TEMPS TODAY WILL BE IN THE MID 90S RESULTING IN HEAT INDICES NEAR 100. A STABLE LAYER AT 650MB PER 12Z IAD RAOB WILL CONTINUE TO WEAKEN AND SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THE OHIO VALLEY AHEAD OF A COLD FRONT. THIS ACTIVITY WILL MOVE INTO THE MID-ATLANTIC LATER THIS AFTERNOON AND EVENING. A LEE TROUGH PRESENT ACROSS THE REGION THIS AFTERNOON MAY CAUSE SHOWERS AND STORMS TO INITIATE NEAR THE BLUE RIDGE MTNS. DUE TO THE WEAK FORCING ALOFT...A INVERSION AND WEAK SHEAR PROFILES ACROSS THE MID-ATLANTIC THIS AFTERNOON... ACTIVITY SHOULD BE SCATTERED AND SUB-SEVERE. LATER TODAY...AS CONDITIONS BECOME MORE FAVORABLE FOR ORGANIZED CONVECTION...A FEW STORMS MAY BECOME STRONG TO SEVERE PRODUCING DMG WINDS. DUE TO THE HEIGHT OF THE FZL...LARGE HAIL IS NOT EXPECTED AT THIS TIME. THE COLD FRONT WILL CROSS THE MID ATLANTIC LATE TONIGHT AS THE UPPER LEVEL TROUGH DIGS INTO THE MIDWEST. SHOWERS AND THUNDERSTORMS MAY PERSIST OVERNIGHT AS MOISTURE AND UPPER LEVEL FORCING LAG BEHIND THE COLD FRONT.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY/...
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SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE THURSDAY. IT WONT BE UNTIL THE TROUGH AXIS CROSSES THE MID ATLANTIC THURSDAY AFTERNOON WILL DRY CONDITIONS AND CLEARING MOVE INTO THE AREA FROM THE NORTH. FCST MAX TEMPS ARE AROUND 80 DEGREES THURSDAY. THE COLD FRONT WILL CONTINUE TO SAG SOUTHWARD THURSDAY NIGHT AND DRY CONDITIONS WILL PERSIST OVERNIGHT. FCST MIN TEMPS IN THE UPPER 50S WEST OF THE BLUE RIDGE TO THE LOW 60S NEAR THE I-95 CORRIDOR. HIGH PRESSURE MOVES INTO THE REGION FRIDAY RESULTING IN CALM AND MOSTLY SUNNY CONDITIONS.
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&& .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...
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HIGH PRESSURE WILL KEEP US DRY FRIDAY NIGHT...FROM THE SHENANDOAH VALLEY TO THE CHESAPEAKE BAY. THERE COULD BE A SHOWER OVER PARTS OF THE POTOMAC HIGHLANDS OTHERWISE. UPPER ENERGY WILL MOVE EAST ACROSS OHIO AND PENNSYLVANIA SATURDAY...BRINGING A CHANCE FOR SHOWERS AND THUNDERSTORMS ACROSS THE REGION. ADDITIONAL SHOWERS OR THUNDERSTORMS MAY DEVELOP INTO SATURDAY NIGHT AS ADDITIONAL ENERGY SLIDES ACROSS THE MID ATLANTIC. THE MAIN STORM SYSTEM OVER THE GREAT LAKES WILL BEGIN TO SLIDE ACROSS THE REGION SUNDAY INTO SUNDAY NIGHT. SEVERAL WAVES OF ENERGY WILL PIVOT AROUND THE MAIN STORM...BRINGING INCREASED CHANCES OF SHOWERS AND THUNDERSTORMS. A COUPLE OF THUNDERSTORMS COULD BRING HEAVY RAIN AND GUSTY WINDS. AS THE MAIN STORM MOVES INTO SOUTHEAST CANADA MONDAY INTO MONDAY NIGHT...ITS ASSOCIATED SURFACE COLD FRONT WILL PUSH TO THE EAST COAST BY TUESDAY MORNING. AHEAD OF THE FRONT...PERHAPS ONE FINAL ROUND OF SHOWERS AND THUNDERSTORMS COULD DEVELOP IN THE REGION. TUESDAY WILL BE DRIER AND COOLER WITH HIGH PRESSURE BUILDING IN FROM THE WEST. THERE COULD BE A LINGERING SHOWER IN THE POTOMAC HIGHLANDS TUESDAY.
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&& .AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
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A COLD FRONT WILL APPROACH THE REGION THIS AFTERNOON AND EVENING. SCT SHRA AND SCT TSRA ARE POSSIBLE AT THE TERMINALS. SOME STRONGER STORMS THIS EVENING MAY PRODUCE GUSTY WINDS. MVFR/IFR CONDITIONS POSSIBLE WITHIN THUNDERSTORMS. VFR CONDITIONS EXPECTED OUTSIDE ACTIVITY. THE COLD FRONT WILL CROSS OVERNIGHT BUT SHRA AND VCTS ARE POSSIBLE INTO THURSDAY. VFR CONDITIONS FRIDAY NIGHT AND SATURDAY WITH LIGHT AND VARIABLE WINDS BECOMING SOUTHERLY. MVFR OR IFR CONDITIONS COULD DEVELOP WITH SHOWER AND THUNDERSTORM ACTIVITY SATURDAY NIGHT...MAINLY NEAR CHO AND MRB TERMINALS. IFR CONDITIONS MAY BE MORE LIKELY AT ANY OF THE TERMINALS SUNDAY WITH SHOWERS AND GUSTY THUNDERSTORMS.
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&& .MARINE...
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SOUTHERLY FLOW WILL CONTINUE ACROSS THE WATERS THIS AFTERNOON AND EVENING. SHOWERS AND THUNDERSTORMS ARE POSSIBLE THIS EVENING. SOME STORMS MAY PRODUCE GUSTY WINDS LATE TONIGHT AND SMW`S ARE POSSIBLE. A COLD FRONT WILL CROSS THE REGION OVERNIGHT AND INTO THURSDAY MORNING. SHOWERS AND ISO THUNDERSTORMS WILL LINGER INTO THURSDAY. HIGH PRESSURE WILL MOVE INTO THE REGION THURSDAY NIGHT AND A SCA IS POSSIBLE LATE THURSDAY AND FRIDAY MORNING AS NRLY WINDS INCREASE ACROSS THE WATERS. SMALL CRAFT ADVISORIES MAY BE NEEDED SATURDAY NIGHT AND SUNDAY WITH GUSTY SOUTH TO SOUTHWEST WINDS AHEAD OF A COLD FRONT.
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&& .TIDES/COASTAL FLOODING...
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A SOUTHERLY FLOW HAS CAUSED TIDAL ANOMALIES TO BE AROUND ONE-HALF TO THREE QUARTERS OF A FOOT ABOVE NORMAL. THE POSITIVE ANOMALIES WILL CONTINUE THIS AFTERNOON AND EVENING...BUT THE NEXT HIGH TIDE WILL BE THE LOWER OF THE TWO SO MINOR FLOODING IS NOT EXPECTED. THE FLOW WILL TURN OFFSHORE BEHIND A SURFACE TROUGH LATE TONIGHT INTO THURSDAY...SO ANOMALIES ARE EXPECTED TO DECREASE DURING THIS TIME.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...HAS LONG TERM...KLW AVIATION...HAS/KLW MARINE...HAS/KLW TIDES/COASTAL FLOODING...HAS

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