Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 310155 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 955 PM EDT SAT MAY 30 2015 .SYNOPSIS... HIGH PRESSURE WILL PERSIST OFFSHORE THROUGH TONIGHT WITH WARM AND HUMID CONDITIONS IN THE MID-ATLANTIC. A COLD FRONT WILL ENTER THE REGION LATE SUNDAY AND STALL OVER THE REGION INTO TUESDAY. HIGH PRESSURE IS EXPECTED TO SLIDE INTO THE REGION FOR THE MIDDLE AND LATTER PORTIONS OF NEXT WEEK. && .NEAR TERM /THROUGH SUNDAY/... PERSISTENT RIDGE OF HIGH PRESSURE REMAINS OFF THE COAST THIS EVENING. SEVERAL SHORTWAVE TROUGHS ARE EVIDENT IN WV IMAGERY OVER THE MS AND OH VALLEY...WHILE MORE ORGANIZED FRONTAL SYSTEM OVER ONTARIO. THIS SYSTEM WILL PLAY A ROLE IN OUR WEATHER THE NEXT SEVERAL DAYS AS IT SUPPRESSES THE RIDGE. FRONTAL ZONE ASSOCIATED WITH NORTHERN STREAM SYSTEM SLIPS INTO SOUTHERN GREAT LAKES TONIGHT...BUT WILL BE HELD UP BY RIDGE AND WAVE OF LOW PRESSURE OVER OH VALLEY. CONVECTION IS DYING OFF AND OPTED TO GO WITH DRIER GUIDANCE THIS EVENING AND REMOVE MOST POPS THROUGH SUNDAY MORNING GIVEN A GENERAL LACK OF FORCING. WITH HIGH DEW POINTS...MIN TEMP WILL ONCE AGAIN BE RELEGATED TO 60S-A70. LATEST READINGS ARE NOTABLY WARMER THAN THIS TIME LAST NIGHT IN MANY LOCALES...LIKELY DUE TO SOUTHERLY FLOW AND CLOUD COVER...SO ITS POSSIBLE LOWS MAY STAY A TICK WARMER THAN CURRENT FORECAST. HOWEVER...CLEARING IN THE NEXT FEW HOURS MIGHT ALLOW FOR A QUICK SHORT DROP-OFF...SO OPTED TO KEEP THE LOW FORECAST AS-IS. WITH CONTINUED SLOWER FRONTAL PROGRESSION...MUCH OF THE FAVORABLE FORCING WILL REMAIN NORTH OF THE AREA THROUGH MUCH OF THE DAY AND THE AREA REMAINS FIRMLY IN THE WARM SECTOR. POPS HAVE BEEN TRIMMED A BIT FURTHER IN SPACE AND TIME. IN FACT SUNDAY MAY NOT LOOK TOO MUCH DIFFERENTLY THAN TODAY...ALTHOUGH THERE MAY BE A LITTLE BETTER COVERAGE OF STORMS IN THE NW CWA AS HEIGHTS LOWER. A LOT OF THE SE CWA MAY ESCAPE MOST OF THE DAY DRY. DEEP LAYER SHEAR MAY INCREASE A LITTLE WITH THE MID LEVEL DISTURBANCES TO OUR NORTH...BUT STILL LOOKS TO BE ON THE WEAK END OF THE SPECTRUM. SPC HAS PLACED MUCH OF THE AREA UNDER A MARGINAL RISK OF SEVERE WX. WITH LITTLE CHANGE TO ATMOS MOISTURE...LOCALLY HEAVY RAIN WILL ALSO BE POSSIBLE. TEMPS WILL BE ABLE TO WARM INTO THE 80S ACROSS MUCH OF THE AREA. && .SHORT TERM /SUNDAY NIGHT THROUGH MONDAY NIGHT/... WITH BETTER FORCING IN PLACE TO OUR NORTH...CONVECTION MAY PERSIST LONGER INTO SUNDAY NIGHT. SOME IMPLICATIONS THAT THERE IS A HIGHER CHANCE OF STORMS MOVING ACROSS NORTHERN MD OVERNIGHT AND HAVE ADJUSTED POPS UP ACCORDINGLY. NO LONGER LOOKS LIKE THERE WILL BE ANY CAA THROUGH SUNDAY NIGHT...SO LOWS WILL AGAIN BE IN THE 60S-A70. A COLD FRONT WILL REMAIN STALLED OUT TO OUR NORTH OVER PENNSYLVANIA WHILE AN UPPER-LEVEL RIDGE CONTINUES TO SLOWLY SIDE FARTHER SOUTH AND EAST AWAY FROM THE AREA. A SOUTHERLY FLOW AHEAD OF THE FRONT WILL CONTINUE TO USHER IN WARM AND VERY HUMID CONDITIONS DURING THIS TIME. THE HEAT AND HUMIDITY WILL LEAD TO MORE SHOWERS AND THUNDERSTORMS. CONVECTION COVERAGE SHOULD BE WIDESPREAD DUE TO MODERATE AMOUNTS OF INSTABILITY...LITTLE TO NO INVERSION...AND A SURFACE TROUGH ACTING AS A LIFTING MECHANISM. SHEAR PROFILES REMAIN MARGINAL...BUT WITH MODERATE AMOUNTS OF INSTABILITY A FEW THUNDERSTORMS MAY BE CAPABLE OF BECOMING SEVERE. THUNDERSTORMS WILL ALSO CONTAIN HEAVY RAINFALL AND LOCALIZED FLASH FLOODING CANNOT BE RULED OUT. THE BEST CHANCE FOR THE STRONGER STORMS WILL BE MONDAY AFTERNOON AND EVENING. && .LONG TERM /TUESDAY THROUGH SATURDAY/... COLD FRONT WILL BE SLOW TO SAG SOUTH OF THE AREA...AND STALLS NEAR THE REGION DURING THE MIDDLE PART OF THE WEEK. EXPECTING POSSIBLY ANOTHER FLARE UP OF SHOWERS AND A FEW THUNDERSTORMS TUESDAY AFTERNOON...MAINLY ACROSS CENTRAL VA/SOUTHERN MD. SOMEWHAT COOLER AIRMASS FILTERS INTO THE REGION BEHIND THE FRONT...BUT GUIDANCE HAS REALLY BACKED OFF ON ANOMALOUSLY COOLER AIR...SO AT THIS TIME EXPECT TEMPERATURES TO BE NEAR NORMAL DURING THE MIDDLE OF THE WEEK. WARMER AND MORE HUMID CONDITIONS RETURN BY THE END OF THE WEEK AS SOUTHERLY FLOW GRADUALLY TAKES OVER AGAIN. CHANCE FOR SHOWERS AND POSSIBLY THUNDERSTORMS INCREASES AGAIN AS WELL...AND SEVERAL ENSEMBLE MEMBERS OF BOTH EC AND GEFS HAVE AN AREA OF LOW PRESSURE DRIFTING UP THE COAST BY NEXT WEEKEND WHICH COULD FURTHER ENHANCE RAIN CHANCES DEPENDING ON TRACK/EVOLUTION. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... OVERALL VFR CONDITIONS THROUGH THE REMAINDER OF THIS EVENING WITH SCT CU AROUND 5 KFT. NO LONGER APPEARS TO BE ANY CHANCE OF THUNDER AT TERMINALS. SOUTHERLY FLOW 10-15 KT. SOME FOG MAY DEVELOP LATE TONIGHT AGAIN WITH CHO AND MRB FAVORED. HAVE LIMITED TO MVFR FOR NOW. MRB MAY HAVE A BETTER CHANCE OF DROPPING LOWER SINCE IT RAINED A LITTLE THERE THIS AFTERNOON. SLOWER FRONTAL TIMING MEANS SUNDAY MAY NOT BE TOO DISSIMILAR TO TODAY. MRB WILL HAVE THE HIGHEST CHANCE OF AFTERNOON STORMS...DIFFERENCE BEING THAT THESE COULD EVENTUALLY SPREAD INTO THE METRO TAFS DURING THE EVENING. QUESTIONS REMAIN HOW MUCH LINGER OVERNIGHT. WINDS REMAIN S OR SW. SHOWERS AND THUNDERSTORMS ARE EXPECTED MONDAY AND MONDAY NIGHT. CONVECTION WILL BE MOST WIDESPREAD DURING THE AFTERNOON AND EVENING. THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND HEAVY RAINFALL THAT REDUCES CIGS/VSBYS BRIEFLY TO IFR LEVELS. NLY FLOW AOB 10 KT...SUB-VFR PSBL IN -SHRA TUE. NELY 10 KT TUE NIGHT-WED W/ VFR EXPECTED. && .MARINE... SOUTHERLY FLOW OVER THE WATERS WITH OFFSHORE HIGH PRESSURE. SCA CONDITIONS OCCURRING OVER THE BAY AND ARE EXPECTED TO CONTINUE INTO THE EARLY OVERNIGHT PERIOD. ONCE MIXING INCREASES SUNDAY...A SIMILAR SITUATION IS EXPECTED TO UNFOLD. HAVE THEREFORE EXTENDED SCA THROUGH SUNDAY EVENING. POSSIBLE THIS MAY NEED TO BE EXTENDED A BIT FURTHER. A LITTLE BETTER CHANCE OF THUNDERSTORMS SUNDAY EVENING VS THIS EVENING. NORTHERN PORTIONS OF THE BAY WOULD BE FAVORED TOWARD SUNDAY EVENING. AN SMW NOT OUT OF THE QUESTION. A SOUTHERLY FLOW WILL CONTINUE MONDAY THROUGH MONDAY NIGHT AHEAD OF A COLD FRONT THAT WILL BE LOCATED TO THE NORTH. A SMALL CRAFT ADVISORY MAY BE NEEDED FOR PORTIONS OF THE WATERS DURING THIS TIME. SHOWERS AND THUNDERSTORMS ARE EXPECTED...WITH THE MOST WIDESPREAD COVERAGE DURING THE AFTERNOON AND EVENING HOURS. GUSTY WINDS ARE POSSIBLE IN THUNDERSTORMS...AND LOCALLY HEAVY RAINFALL MAY REDUCE VSBYS BRIEFLY BELOW ONE MILE AT TIMES. SCA GUSTS POSSIBLE IN NLY FLOW INTO TUE...THEN SUBSIDES TUE PM- WED. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 2 AM EDT SUNDAY FOR ANZ530>534- 537>543. SMALL CRAFT ADVISORY FROM 2 PM SUNDAY TO 2 AM EDT MONDAY FOR ANZ530>534-537>543. && $$ SYNOPSIS...BJL NEAR TERM...ADS/RCM SHORT TERM...BJL/ADS LONG TERM...BJL AVIATION...BJL/ADS/DFH/RCM MARINE...BJL/ADS/DFH/RCM

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