Area Forecast Discussion
Issued by NWS Sterling, VA

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885 FXUS61 KLWX 040759 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 359 AM EDT WED MAY 4 2016 .SYNOPSIS... SURFACE LOW PRESSURE WILL REMAIN ACROSS THE AREA TODAY. UPPER LEVEL LOW PRESSURE IS EXPECTED TO IMPACT THE AREA THURSDAY AND FRIDAY BEFORE HIGH PRESSURE RETURNS SATURDAY EVENING. A WEAK COLD FRONT IS EXPECTED TO PUSH THROUGH THE REGION SUNDAY. && .NEAR TERM /TODAY/... LONG WAVE PATTERN AMPLIFYING ACROSS THE CONUS WITH LOW DESCENDING ACROSS THE GREAT LAKES AND RIDGE OVER THE INTER-MOUNTAIN WEST TAKING ON A CLASSIC OMEGA SHAPE (A PATTERN BLOCK). THE EAST SIDE OF THIS BLOCK WILL BE WET WITH THE MID-ATLANTIC IN CONTINUED CLOUDINESS THROUGH SATURDAY. AS OF 3AM...1004MB SFC LOW OVER NERN NC WITH ONSHORE FLOW OVER THE CENTRAL MID-ATLANTIC ALLOWING LOW CLOUDS TO SPREAD IN. LIGHT RAIN WILL DEVELOP OVER THE AREA THROUGH THE MID-MORNING. THEN THIS AFTERNOON ELEVATED INSTABILITY AHEAD OF THE APPROACHING LOW AIDS SHOWER DEVELOPMENT WITH ISOLATED THUNDER OVER SWRN ZONES. && .SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/... A CLOSED LOW SWINGS OVER THE AREA TONIGHT THROUGH THURSDAY...THEN STALLS AT LEAST INTO SATURDAY. THIS WILL BRING ABOUT A NOTABLY WET STRETCH WITH INTERMITTENT RAIN. DESPITE IT HAVING ALREADY BEEN WET RECENTLY...THERE IS A SPRING RAINFALL DEFICIT ACROSS THE AREA OF ONE TO THREE INCHES. SO THIS SHOULD BE SEEN AS A BENEFICIAL STRETCH. POTENTIAL HAZARDOUS WEATHER IN THIS STRETCH. RAIN MAY BECOME EXCESSIVE...PARTICULARLY LATE TONIGHT THROUGH THURSDAY AS THE UPR LOW OVER ERN KY TRANSFERS ENERGY TO A COASTAL LOW. MOISTURE CONVERGENCE ALONG THIS LINE (GUIDANCE CONSENSUS CURRENTLY FEATURES THIS CONVERGENCE ACROSS CNTRL VA) COULD ALLOW MODERATE TO LOCALLY HEAVY RAIN OVER THE SAME AREAS FOR HOURS. THIS...WITH TERRAIN ENHANCEMENT IN THE AREA COULD LEAD TO A FEW TO SEVERAL INCHES OF RAIN AND FLOODING. CURRENT SIX-HOUR FFG IS 1.5 TO 3 INCHES OVER SWRN ZONES. A NOTE ABOUT THIS WILL BE ADDED TO THE HWO. THE LOW BECOMES VERTICALLY STACKED OVER THE AREA THURSDAY NIGHT AND PERSISTS FRIDAY. FOCUS OF RAIN SHIFTS ACROSS THE BALT-WASH METRO. THIS LOOKS LESS INTENSE AS THE THURSDAY AREA WITH QPF AN INCH OR SO. && .LONG TERM /SATURDAY THROUGH TUESDAY/... THE UPR CUTOFF LOW OVR THE ERN U.S. WHICH WE`VE BEEN WRITING ABT FOR THE PAST SVRL DAYS SEEMS TO BE EARNING THE TERM "OMNIPRESENT" AS LATEST MDLS NOW KEEP IT OVR THE MID ATLC THRU SAT...KEEPING THE 1ST HALF OF THE WKND A CLDY COOL RAINY CONTINUATION OF WHAT THIS WK HAS BEEN AS A WHOLE. SUPERBLEND GIVING HIGHS IN THE LM70S SAT - THIS MAY BE A STRETCH AND WL BE DEPENDENT ON WHETHER BRKS DVLP IN THE AFTN CLDS...AND IF BRKS DO DVLP WL RW FORM AS A RESULT OF THE HTG IN THE MOIST ENVIRONMENT? A CD FNT IS PROGGED TO MOVE INTO THE RGN SUNDAY/UPR LVL SHORT WV DIVE INTO THE ERN GRT LKS. THIS TOO MAY LEAD TO A CHC OF RW/ISOLD TRW. IT LOOKS LK WE`LL FINALLY BE ABLE TO SAY "BON VOYAGE" TO THE UPR LOW MON...AND THE UPR RIDGE WHICH WL HV BEEN OVR THE ROCKIES FOR MULTIPLE DAYS. SUNNIER SKIES NEXT MON AND TUE. && .AVIATION /06Z WEDNESDAY THROUGH SUNDAY/... ONSHORE FLOW THROUGH THURSDAY AS LOW PRESSURE MOVES EAST OFFSHORE AND DEEP LOW PRESSURE MOVES SOUTH INTO THE CAROLINAS. INTERMITTENT IFR/MVFR CONDS TODAY THROUGH FRIDAY NIGHT. RAIN DEVELOPS THIS MORNING WITH PERIODIC SHOWERS THEN THIS AFTERNOON THROUGH FRIDAY NIGHT. ISOLATED THUNDER INVOF KCHO THIS AFTERNOON AND THURSDAY AFTERNOON. LWRD CIGS AGN PSBL SAT...THEN IMPRVG CONDS SUNDAY. && .MARINE... LIGHT ONSHORE FLOW THROUGH THURSDAY AS LOW PRESSURE MOVES EAST THIS MORNING AND DEEP LOW PRESSURE MOVES SOUTH INTO THE CAROLINAS. SCA MAY BE NECESSARY AS LOW DEVELOPS THURSDAY NIGHT INTO FRIDAY. WILL NEED TO MONITOR FOR POTENTIAL SCA ALSO INTO THIS WEEKEND AS LOW MOVES OUT. NO PROBS XPCTD ON THE WATERS SAT. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ PRODUCTS...BAJ/WOODY!

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