Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 051443 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1043 AM EDT THU MAY 5 2016 .SYNOPSIS... UPPER LEVEL LOW PRESSURE OVER KENTUCKY WILL SWING SOUTHEAST INTO THE CAROLINAS TODAY...BEFORE MOVING UP THE MID-ATLANTIC COAST TONIGHT. THIS LOW WILL STALL OVER THE AREA FRIDAY INTO SATURDAY BEFORE SHIFTING OUT TO SEA. A COLD FRONT WILL CROSS THE AREA SATURDAY NIGHT INTO SUNDAY BEFORE A WARM FRONT LIFTS OVER THE AREA MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH TONIGHT/...
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14Z WATER VAPOR IMAGERY AND RADAR REFLECTIVITY NOTING CLOSED UPPER LVL LOW PIVOTING SLOWLY OVER KY. THIS LOW IS EXPECTED IS TO SLOWLY PROGRESS TO THE SOUTH TODAY...PUSHING TO THE EAST AND OFFSHORE TONIGHT. ON GOING RAIN SW CORNER OF THE CWA THIS MORNING IN ASSOCIATION WITH THIS LOW. AS THE LOW MOVES TO THE SOUTH AND EAST...THE RAIN IS EXPECTED TO SLOWLY PIVOT NORTH...EVENTUALLY MVG INTO EASTERN AREAS LATER TODAY. NE FLOW AT THE SFC CURRENTLY WITH SW FLOW ALOFT RESULTING IN DZ AT MOST SITES NORTH OF THE ON GOING RAIN. AS THE LOW MOVES...ENERGY ASSOCIATED WITH THE LOW SPREADS ACROSS THE CWA...WHICH WILL AID IN TRIGGERING SHOWERS...LATE AFTN INTO TONIGHT. PCPN WILL INCREASE MIN TEMPS AROUND 50F TONIGHT AS THE UPR LOW CENTER SHIFTS TO CAPE HATTERAS. RAIN GENERALLY INCREASES IN COVERAGE OVERNIGHT. QUARTER TO HALF INCH QPF OVERNIGHT.IN COVERAGE AND INTENSITY OVERNIGHT AS WELL. WILL CONTINUE TO HIGHLIGHT FLOOD THREAT IN HWO FOR WESTERN AREAS WHERE BETWEEN 1-2 INCHES HAS ALREADY BEEN REPORTED. ATTM...AREAS TO THE EAST LOOK TO HAVE LESS OF A FLOOD THREAT.
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&& .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... DEEP UPR LOW STALLS/LOOPS OVER THE AREA FRIDAY THROUGH MIDDAY SATURDAY PER 00Z GFS/ECMWF. CONTINUED LOW CLOUDS AND RAIN FRIDAY WITH AN ADDITIONAL HALF TO ONE INCH QPF AS THE LOW BECOMES VERTICALLY STACKED. LOW SLOWLY FILLS FRIDAY NIGHT THROUGH SATURDAY WITH LOWER POPS AND LIGHT RAIN RATES. TEMPERATURES 5-10 DEGREES HIGHER SATURDAY OVER FRIDAY AS CLOUD COVER STEADILY DISSIPATES THROUGH SATURDAY. COLD FRONT BEHIND THE EJECTING WHOLE SYSTEM APPROACHES SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... SOME IMPROVEMENT EXPECTED IN THE EXTENDED PERIOD OF THE FORECAST...HOWEVER RELATIVELY UNSETTLED WEATHER LIKELY TO CONTINUE. WILL BE LOOKING AT A COLD FRONT CROSSING THE REGION SUNDAY MORNING WITH A CHANCE OF RAIN SHOWERS...FOLLOWED SOME BRIEF DRYING OCCURRING BEHIND IT LATER SUNDAY AND INTO SUNDAY NIGHT. HOWEVER...THIS WILL BE QUICKLY FOLLOWED BY A WARM FRONT ON MONDAY...USHERING IN SOUTHWEST FLOW...WARMTH...AND ADDITIONAL MOISTURE. SOME VARIATIONS IN MODEL SOLUTIONS...BUT THERE ARE INDICATIONS OF A COLD FRONT NEARING THE REGION ON WEDNESDAY. WHILE WIDESPREAD RAIN IS NOT EXPECTED...THE INCREASING WARMTH AND MOISTURE COMBINED WITH THE PRESENCE OF FRONTAL BOUNDARIES WILL KEEP CHANCES FOR SCATTERED SHOWERS AND/OR THUNDERSTORMS IN THE FORECAST FOR THE BEGINNING OF NEXT WEEK. TEMPERATURES WILL REBOUND TO NEAR AND EVENTUALLY ABOVE NORMAL WITH HIGHS REACHING BACK UP INTO THE 70S AND 80S BY NEXT WEEK. && .AVIATION /14Z THURSDAY THROUGH MONDAY/...
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CONDITIONS VARYING BTW IFR AND MVFR WITH DZ AND STRATUS IMPACTING THE TERMINALS. LIGHT RAIN AT KCHO FOR MOST OF THE DAY...KEEPING MAINLY IFR. MODEL GUIDANCE HINTS AT SLIGHT IMPROVEMENT LATE IN THE DAY BUT CONFIDENCE IS LOW OUTSIDE OF KMRB OF THIS OCCURRING MORE THAN IS ALREADY NOTED IN TAFS. BY TONIGHT...INCREASED COVERAGE AND INTENSITY IN THE RAIN WILL KEEP CONDITIONS MAINLY IFR. WINDS NE THRU THE PERIOD...10 KTS OR LESS. SYSTEMS EJECTS EAST SATURDAY WITH A COLD FRONT CROSSING LATE SATURDAY NIGHT INTO SUNDAY. VFR CONDITIONS ARE EXPECTED SUNDAY THROUGH MONDAY.
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&& .MARINE...
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..BUT NOT ANTICIPATING VFR FOR THE TAF PERIOD. ONSHORE FLOW 10 TO 15 KT CONTINUES THROUGH TONIGHT AS LOW PRESSURE SWINGS THROUGH THE CAROLINAS. NORTH WINDS 10 TO 15 KT THEN THROUGH SATURDAY AS LOW PRESSURE STALLS OVER THE AREA. A SMALL CRAFT ADVISORY MAY BE NEEDED ON SUNDAY WITH GUSTY NORTHWEST WINDS BEHIND FRONTAL PASSAGE. SUB-SCA CONDITIONS THEN FOLLOW ON MONDAY.
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&& .HYDROLOGY... LOCALLY HEAVY RAIN OVER CNTRL VA AND THE SHENANDOAH VALLEY AND ALLEGHENY HIGHLANDS. NO WATCH AS OF NOW...BUT WILL NEED TO MONITOR PROGRESS OVER LARGE SCALE CONVERGENCE AS AN UPPER LOW PRESSURE SYSTEM DEVELOPS AS IT MOVES OVER THE REGION THROUGH TONIGHT. && .TIDES/COASTAL FLOODING... MINOR FLOODING FROM ONSHORE FLOW. WIDESPREAD MINOR AT PREFERRED HIGH TIDE AND FOR EACH HIGH TIDE AT STRAITS POINT AND SW WATERFRONT DC/ALEXANDRIA THROUGH SATURDAY. ADVISORIES IN EFFECT THROUGH TONIGHT. AMENDMENTS TO THIS AS NEEDED. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR DCZ001. MD...COASTAL FLOOD ADVISORY FROM 10 PM THIS EVENING TO 6 AM EDT FRIDAY FOR MDZ018. COASTAL FLOOD ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM EDT FRIDAY FOR MDZ014. COASTAL FLOOD ADVISORY UNTIL 6 AM EDT FRIDAY FOR MDZ017. VA...COASTAL FLOOD ADVISORY UNTIL MIDNIGHT EDT TONIGHT FOR VAZ054. WV...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...BAJ NEAR TERM...SEARS SHORT TERM...BAJ LONG TERM...MM AVIATION...BAJ/SEARS/MM MARINE...BAJ/SEARS/MM HYDROLOGY...BAJ TIDES/COASTAL FLOODING...BAJ

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