Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 241846 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 246 PM EDT THU JUL 24 2014 .SYNOPSIS...
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A COLD FRONT WILL SLOWLY PASS THROUGH SOUTHERN VIRGINIA TODAY. HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH FRIDAY BEFORE MOVING OFF THE COAST DURING THE WEEKEND. A COLD FRONT WILL PASS THROUGH THE AREA EARLY NEXT WEEK.
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&& .NEAR TERM /THROUGH FRIDAY/...
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AN UPPER LEVEL TROUGH WILL CONTINUE TO APPROACH THE MID-ATLANTIC THIS AFTERNOON. A SHORTWAVE TROUGH HAS MOVED INTO WV AND CONVECTION HAS INITIATED ACROSS THE APPALACHIANS. THIS ACTIVITY WILL CONTINUE TO MOVE E-SE AND STAY IN THE VICINITY OF THE COLD FRONT THAT IS IN SRN VA. THE FOOTHILLS AND PIEDMONT REGION IN THE MID-ATLANTIC ARE STILL TAPPING INTO 500-1000 J/KG OF CAPE AND SHOWERS AND THUNDERSTORMS HAVE DEVELOPED AND TRACKED E-SE. THIS ACTIVITY WILL SLOWLY MOVE SOUTH AS THE FRONT SLOWLY MOVES SOUTHWARD AND BE NON- SEVERE IN THIS REGION. DRY NRLY FLOW HAS ADVECTED INTO THE REGION BEHIND THE COLD FRONT AND DEWPTS HAVE DROPPED IN THE 50S NEAR THE MASON DIXON LINE TO THE UPPER 60S AT CHO. DEWPTS WILL CONTINUE TO DROP FROM NORTH TO SOUTH TONIGHT AS THE COLD FRONT MOVES AWAY FROM THE REGION. THE UPPER LEVEL TROUGH AXIS WILL CROSS THE REGION OVERNIGHT AND DRY AND COOLER CONDITIONS WILL ENSUE. FCST MIN TEMPS RANGE FROM THE UPPER 50S IN THE HIGHLANDS TO THE LOW TO MID 60S NEAR I-95 CORRIDOR. HIGH PRESSURE WILL MOVE INTO THE REGION FRIDAY. THE CENTER OF THE HIGH MOVES OFF THE COAST BY FRIDAY AFTERNOON AND LIGHT RETURN FLOW MOVES INTO THE REGION. FCST MAX TEMPS ARE IN THE LOW TO MID 80S. A CU FIELD SHOULD DEVELOP AS MOISTURE ALOFT PERSISTS. A FEW SHOWERS MAY BE POSSIBLE IN THE CENTRAL FOOTHILLS AS MOISTURE CREEPS INTO THE REGION FRI AFTERNOON. CONFIDENCE OF SHOWERS IS LOW AT THIS TIME.
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&& .SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...
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WESTERLY ZONAL FLOW ALOFT WILL CONTINUE INTO SATURDAY AS THE HIGH MOVES WELL OFF THE EAST COAST. A SHORTWAVE TROUGH MAY CROSS NORTH OF THE REGION SATURDAY AND SHOWERS AND THUNDERSTORMS MAY BE POSSIBLE NEAR THE MASON DIXON LINE. A LEE TROUGH IS EXPECTED TO FORM AND MAY INITIATE THUNDERSTORMS. MOISTURE BEGINS TO POOL INTO THE REGION WITH INCREASE PWATS AND THETA-E ADVECTION. FCST MAX TEMPS WILL BE IN THE UPPER 80S.
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&& .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...
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A TROUGH TO THE EAST OF THE APPALACHIAN MOUNTAINS SATURDAY NIGHT AND PASSING UPPER LEVEL ENERGY MAY BE ENOUGH TO SPAWN A COUPLE OF SHOWERS AND THUNDERSTORMS. THERE IS A BETTER CHANCE FOR HEAVIER SHOWERS AND GUSTY THUNDERSTORMS SUNDAY AND SUNDAY NIGHT AS THE MAIN UPPER LEVEL FEATURE OVER THE GREAT LAKES BEGINS TO TREK ITS WAY EASTWARD...ALLOWING A SURFACE LOW PRESSURE TO DEVELOP ALONG THE ALREADY-ESTABLISHED TROUGH OF LOW PRESSURE ALONG THE SHENANDOAH VALLEY. THE MAIN THREAT FROM THE THUNDERSTORMS WILL BE DAMAGING WINDS AS LAPSE RATES APPEAR FAVORABLE AND MID LEVEL AND UPPER LEVELS MAY BE STRONGER THAN RECENT DAYS. AS THE MAIN UPPER LEVEL 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 MONDAY INTO MONDAY EVENING. TUESDAY AND WEDNESDAY WILL BE NOTICEABLY DRIER AND COOLER WITH HIGH PRESSURE BUILDING IN FROM THE WEST. A GRADUAL RETURN FLOW THURSDAY WILL BRING MOISTURE BACK INTO THE REGION. HIGH PRESSURE WILL BE OFFSHORE BY THIS TIME. SOME WEAK UPPER LEVEL ENERGY WILL SLIDE NORTHWARD AND COULD SPAWN A SHOWER OR THUNDERSTORM IN THE HIGHER TERRAIN.
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&& .AVIATION /19Z THURSDAY THROUGH TUESDAY/...
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VFR CONDITIONS EXPECTED TODAY AND TONIGHT. SHOWERS WILL TAPER OFF THIS AFTERNOON AND EVENING AS A COLD FRONT ACROSS SRN VA MOVES AWAY FROM THE REGION. WINDS WILL REMAIN OUT OF THE N AT 5-10 KTS. HIGH PRESSURE WILL MOVE INTO THE REGION TONIGHT AND CONTINUE FRIDAY. VFR CONDITIONS EXPECTED FRIDAY. SOUTHERLY FLOW WILL BEGIN FRIDAY AFTERNOON AND CONTINUE INTO SATURDAY. SHOWERS AND THUNDERSTORMS POSSIBLE SATURDAY AFTERNOON. MVFR OR IFR CONDITIONS COULD DEVELOP WITH SHOWER AND THUNDERSTORM ACTIVITY SATURDAY NIGHT...MAINLY NEAR CHO AND MRB TERMINALS. SOUTHERLY WINDS AT 5 TO 10 KNOTS BUT GUSTING 15 TO 20 KNOTS CLOSE TO THE CHESAPEAKE BAY. IFR CONDITIONS MAY BE MORE LIKELY AT ANY OF THE TERMINALS SUNDAY INTO SUNDAY NIGHT WITH HEAVY SHOWERS AND GUSTY THUNDERSTORMS. SOUTH WINDS BECOMING SOUTHWEST AROUND 10 KNOTS AND GUSTING 15 TO 20 KNOTS NEAR THE BAY. VFR CONDITIONS ON MONDAY WITH HIGH PRESSURE BUILDING IN FROM THE WEST. WINDS BECOMING WEST AT 10 KNOTS WITH AN APPROACHING COLD FRONT.
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&& .MARINE...
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A COLD FRONT WILL CONTINUE TO MOVE AWAY FROM THE WATERS TODAY. NORTHERLY CHANNELING IS EXPECTED TODAY AND WINDS SHOULD INCREASE LATE TONIGHT AND INTO FRIDAY MORNING. A SCA IS IN EFFECT DURING THIS TIME FOR THE MD CHESAPEAKE BAY SOUTH OF POOLES ISLAND AND THE LOWER TIDAL POTOMAC. HIGH PRESSURE MOVES OVER THE WATERS FRIDAY AND WINDS WILL SUBSIDE BEFORE BECOMING SOUTHERLY BY FRI AFTERNOON. SRLY WINDS WILL CONTINUE INTO SATURDAY. SMALL CRAFT ADVISORIES MAY BE NEEDED SATURDAY NIGHT THROUGH MONDAY WITH GUSTY SOUTHWEST TO WESTERLY WINDS AHEAD OF A COLD FRONT.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 2 AM TO 8 AM EDT FRIDAY FOR ANZ531>534-537-539>543. && $$ SYNOPSIS...HAS NEAR TERM...HAS SHORT TERM...HAS LONG TERM...KLW AVIATION...HAS/KLW MARINE...HAS/KLW

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