Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 210127 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 927 PM EDT WED AUG 20 2014 .SYNOPSIS...
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HIGH PRESSURE WILL LINGER OVER THE DEEP SOUTH THROUGH THIS WEEKEND AND LOW PRESSURE WILL CONTINUE TO DISSIPATE OVER THE GREAT LAKES THROUGH THURSDAY. HIGH PRESSURE WILL BUILD OVER NEW ENGLAND FRIDAY AND SPREAD SOUTHWEST THROUGH THE WEEKEND THEN PERSIST OVER THE MID-ATLANTIC INTO THE MIDDLE OF NEXT WEEK.
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&& .NEAR TERM /THROUGH THURSDAY/...
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HEAVY SHOWERS AND THUNDERSTORMS WILL CONTINUE TO MOVE SOUTH FROM CHARLOTTESVILLE THROUGH THE LATE EVENING. AN UPR RIDGE WILL CONTINUE TO DEVELOP OVER THE ERN CONUS WITH THE AXIS STALLING OVER THE MS RIVER THURSDAY. A NWLY JET FROM THIS AXIS WILL SHIFT ACROSS THE NORTHERN MID-ATLANTIC...PUTTING THE CENTRAL MID-ATLANTIC IN THE PREFERRED RIGHT EXIT REGION. THIS WILL AID LIFT AND BULK SHEAR TOMORROW. REMNANT BOUNDARIES FROM THE ACTIVITY TONIGHT COULD FACTOR INTO WHERE THUNDERSTORMS INITIATE/FAVOR. FURTHER MORE...ORGANIZED CONVECTIVE STORMS FROM THE MIDWEST WILL SHIFT SOUTHEAST TOWARD THE AREA. MLCAPE LOOKS LIMITED TO AROUND 1000 J/KG DUE TO WEAK LAPSE RATES...BUT THAT IS SIMILAR TO TODAY...SO IT SHOULD BE SUFFICIENT FOR ACTIVITY. EXPECT MORE ISOLATED SEVERE THUNDERSTORMS...MAINLY DAMAGING WIND. PWATS ARE EXPECTED TO RISE NEAR 2 INCHES THURSDAY PRODUCING A THREAT FOR LOCALIZED FLASH FLOODING. MAX TEMPS MID TO UPR 80S AGAIN WITH DEWPOINTS IN THE UPR 60S FOR HEAT INDEX NEAR 90F.
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&& .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY/... THE CHANCE OF SHOWERS AND THUNDERSTORMS WILL CONTINUE THURSDAY NIGHT AND INTO FRIDAY AS A 250MB JET SITS NEAR THE REGION AND DISTURBANCES APPROACH FROM THE GREAT LAKES. SUBSIDENCE BEHIND THE DEPARTING DISTURBANCES MAY LEAD TO CLEARING FRIDAY AND THEREFORE INSTABILITY WILL LIKELY INCREASE. AT THIS TIME...CONFIDENCE IS LOW ON THE TIMING OF SHOWERS AND THUNDERSTORMS. FCST MAX TEMPS WILL REACH THE LOW 80S ON FRIDAY. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... A WEAK WAVE OF LOW PRESSURE FOCUSED IN THE MID AND UPPER LEVELS WILL CROSS THE AREA OVERNIGHT FRIDAY...PROVIDING ONE FINAL PERIOD OF ENHANCED RAINFALL AS A BACKDOOR COLD FRONT MOVES THROUGH AT THE SURFACE. A SUBTROPICAL RIDGE WILL BUILD OVER THE EASTERN US FOR WEEKEND AS SURFACE HIGH PRESSURE CENTERED OVER THE NORTHEASTERN US RIDGES DOWN THE EASTERN SEABOARD. THIS RIDGING COMBINED WITH EASTERLY FLOW AROUND THE NORTH SIDE OF A COASTAL LOW OFF OF CAPE HATTERAS WILL BRING ONSHORE FLOW FOR THE MID-ATLANTIC MIDDAY SATURDAY THROUGH THE BEGINNING OF NEXT WORKWEEK. THE MARINE LAYER THAT WILL FILL IN WILL BRING SEASONABLY COOL AND MOIST AIR...LEADING TO A LOW CLOUD DECK THAT WILL HANG AROUND THROUGH THE WEEKEND AND LIKELY INTO MONDAY EVENING...PARTICULARLY EAST OF THE BLUE RIDGE. CHANCE POPS WILL REMAIN IN THE FORECAST ALONG AND WEST OF THE BLUE RIDGE WHERE THERE WILL BE AN UPSLOPE COMPONENT TO THE MOIST EASTERLY FLOW. THE SURFACE HIGH WILL MIGRATE OFF OF THE MID-ATLANTIC COAST MONDAY NIGHT AND SOUTHERLY FLOW WILL BEGIN TO FILL IN LOCALLY. THIS WILL SIGNAL AN INCREASE IN TEMPERATURES AS HIGHS WILL GO FROM THE MID TO UPPER 70S SATURDAY THROUGH MONDAY TO NEAR 80 TUESDAY AND MID 80S WEDNESDAY. NO SIGNIFICANT PRECIPITATION FEATURES ARE EXPECTED THROUGH THE FIRST HALF OF NEXT WEEK. && .AVIATION /01Z THURSDAY THROUGH MONDAY/...
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SHRA AND TSRA WILL CONTINUE TO MOVE SOUTH FROM CHARLOTTESVILLE THIS EVENING. LIGHT SOUTHERLY FLOW WILL KEEP MOISTURE IN THE REGION OVERNIGHT AND PATCHY IFR VSBYS ARE POSSIBLE AT MRB AND CHO. MVFR VSBYS ARE POSSIBLE AT IAD. MVFR/IFR CIGS ARE POSSIBLE NEAR BWI-MTN BUT CONFIDENCE IS LOW AT THIS TIME. SHRA AND TSRA POSSIBLE THURSDAY AFTERNOON AND INTO FRIDAY AND MAY CAUSE MVFR/IFR RESTRICTIONS. PERIODS OF LOW CEILINGS ARE POSSIBLE AS A MID AND UPPER LEVEL DISTURBANCE CROSSES THE AREA FRIDAY NIGHT AND THEN AGAIN OVER THE WEEKEND AND INTO EARLY NEXT WEEK AS A MARINE AIRMASS SETTLES INTO THE AREA.
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&& .MARINE...
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SOUTHERLY FLOW WILL CONTINUE ON THE WATERS THROUGH FRIDAY. WINDS GUSTED TO AROUND 20 KT ON MAIN PORTIONS OF THE WATERS THIS AFTERNOON AS THUNDERSTORM ACTIVITY MOVED THROUGH THE AREA. ANOTHER ROUND OF THUNDERSTORMS ARE EXPECTED THURSDAY AFTERNOON. A SMALL CRAFT ADVISORY MAY BE NECESSARY SATURDAY NIGHT THROUGH SUNDAY NIGHT IN BREEZY EASTERLY FLOW AROUND THE NORTH SIDE OF A COASTAL LOW OFF OF THE NORTH CAROLINA FLOW.
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&& .TIDES/COASTAL FLOODING...
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COASTAL FLOOD ADVISORY FOR ANNE ARUNDEL COUNTY. SLY FLOW HAS INCREASED THIS EVENING...WHICH SHOULD KEEP WATER LEVELS AT LEAST THREE QUARTERS OF A FOOT AT ANNAPOLIS AND CAUSE MINOR COASTAL FLOODING AT THAT SENSITIVE SITE. THE GAUGE STOPPED REPORTING THIS AFTERNOON...AND IT IS NOT KNOWN WHEN DATA WILL BE RESTORED. HIGH TIDE IS AT 3:21AM AT THE NAVAL ACADEMY. WATER LEVELS WILL BE ELEVATED ELSEWHERE. WILL NEED TO MONITOR THE UPPER TIDAL POTOMAC FOR POTENTIALLY MEETING THE MINOR THRESHOLD AT THE SOUTHWEST WATERFRONT.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...COASTAL FLOOD ADVISORY FROM 1 AM TO 6 AM EDT THURSDAY FOR MDZ014. VA...NONE. WV...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...BAJ/HAS NEAR TERM...BAJ/HAS SHORT TERM...HAS LONG TERM...CEB AVIATION...BAJ/HAS/CEB MARINE...BAJ/HAS/CEB TIDES/COASTAL FLOODING...BAJ

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