Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 011841 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 241 PM EDT MON SEP 1 2014 .SYNOPSIS...
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A BERMUDA HIGH WILL PERSIST THROUGH TUESDAY. A COLD FRONT WILL CROSS THE AREA TUESDAY NIGHT...FOLLOWED BY HIGH PRESSURE THROUGH THE REST OF THE WEEK.
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&& .NEAR TERM /THROUGH TONIGHT/...
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CONVECTIVE TEMPERATURES HAVE BEEN REACHED ACROSS THE CWA...CU HAVE BECOME MORE PRONOUNCED AND AN UPTICK IN SHOWERS HAVE BEEN OBSERVED OVER THE LAST HOUR OR TWO. CONVECTION WILL LIKELY GROW INTO THUNDERSTORMS AS PEAK HEATING CONTRIBUTES TO INCREASED INSTABILITY. LOW LEVELS REMAIN MOIST AS WELL...WITH DEWPOINTS WITHIN A COUPLE DEGREES OF 70 DEGREES ALTHOUGH PRECIPITABLE WATERS LIKELY HAVE DECREASED A LITTLE BIT DUE TO MID-LEVEL DRY AIR. BASED ON RADAR TRENDS AND INCORPORATING LATEST RUNS OF HIGH RESOLUTION MODELS...CONVECTION OVER WESTERN MD/EASTERN WV/NORTHERN VA WILL MOVE EASTWARD OVER THE NEXT SEVERAL HOURS. ADDITIONAL CONVECTION UPSTREAM COULD ALSO MAKE IT INTO THE CWA BEFORE SUNSET. GIVEN THE HIGH MOISTURE ENVIRONMENT...HEAVY RAINFALL WILL BE THE PRIMARY CONCERN WITH THUNDERSTORMS BUT STORM MOTION SHOULD BE SUFFICIENT ENOUGH TO LIMIT FLASH FLOOD POTENTIAL. CAN/T RULE OUT LOCALLY GUSTY WINDS IN STRONGER STORMS EITHER BUT GIVEN WEAK SHEAR SEVERE RISK IS LOW. MUCH OF THE ACTIVITY WILL MOVE EAST/DISSIPATE BY THE TIME THE SUN SETS...ALTHOUGH CAN/T RULE OUT A ROGUE SHOWER ACROSS THE HIGHLANDS THROUGH MUCH OF THE EVENING.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/...
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COLD FRONT WILL STILL BE LOCATED ACROSS THE OHIO VALLEY AT 12Z TUE. BUT FRONT WILL MARCH EASTWARD THROUGH THE DAY...MAKING IT TO THE POTOMAC HIGHLANDS BY LATE AFTERNOON. PRE-FRONTAL ENVIRONMENT WILL BE WARM AND MOIST...BUT CONVECTION LIKELY WAITS UNTIL THE FRONT GETS CLOSER TO THE CWA AND HAVE POPS EXPANDING EASTWARD WITH TIME HIGHEST IN THE EVENING ACROSS THE INTERSTATE 95 CORRIDOR. THERE IS THE RISK FOR A FEW STORMS TO BECOME SEVERE /DAMAGING WIND GUSTS/ TUESDAY...ESPECIALLY BEFORE DARK DUE TO THE COMBINATION OF INSTABILITY AND INCREASED SHEAR. CONFIDENCE IS LOWER FURTHER DOWNSTREAM ONCE THE SUN SETS. FRONT MOVES THROUGH AT NIGHT. POPS LOWER FROM WEST TO EAST. DRIER AIR MOVES IN FOR WEDNESDAY WITH THE RETURN OF SUNSHINE. WHILE DEWPOINTS ARE LOWER...DOWNSLOPING WILL SUPPORT ABOVE NORMAL TEMPERATURES WHICH STILL MAY BE NEAR 90. SAME TYPE OF SCENARIO ON THURSDAY.
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&& .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
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WEAK SURFACE TROUGH...MOISTURE AND WEAK PVA MAY BE ENOUGH TO SUPPLY A SLIGHT CHANCE OF SHOWERS/THUNDERSTORMS FRIDAY. INCREASED MOISTURE AND THE PASSAGE OF COLD FRONT WILL SUPPORT DEVELOPMENT OF STRONGER ACTIVITY OVER THE WEEKEND AND INTO MONDAY.
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&& .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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SCT SHRA/TSRA WILL MOVE EASTWARD ACROSS THE HUBS OVER THE NEXT SEVERAL HOURS...LIKELY ENDING BY SUNSET. VCTS CURRENTLY IN TAFS...BASED ON RADAR TRENDS MAY NEED TO AMEND FOR TSRA INCLUSION. REST OF THE NIGHT INTO TUESDAY MORNING SHOULD BE DRY...TSRA POSSIBLE AGAIN TUESDAY AFTERNOON/EVENING AHEAD OF A COLD FRONT. NO SIGNIFICANT WEATHER EXPECTED MID TO LATE WEEK.
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&& .MARINE...
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PRIMARY CONCERN THIS EVENING WILL BE GUSTY WINDS AND LIGHTNING IN SCATTERED SHOWERS AND THUNDERSTORMS THAT AFFECT THE WATERS THROUGH EARLY EVENING. ACTIVITY SHOULD DIMINISH WITH SUNSET. APPROACHING COLD FRONT WILL LIKELY PRODUCE SCATTERED THUNDERSTORMS LATE TUESDAY AFTERNOON AND EVENING AS WELL...WITH GUSTY WINDS AGAIN POSSIBLE. FRONT MOVES THROUGH TUESDAY NIGHT WITH HIGH PRESSURE BUILDING IN FOR WEDNESDAY. SOUTHERLY CHANNELLING/SCA CONDITIONS COULD BE POSSIBLE LATE FRIDAY. COLD FRONT EXPECTED TO MOVE THROUGH OVER THE WEEKEND.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BPP/CEM NEAR TERM...BPP SHORT TERM...BPP LONG TERM...CEM AVIATION...BPP/CEM MARINE...BPP/CEM

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