Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 020113 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 913 PM EDT WED JUL 1 2015 .SYNOPSIS... A COLD FRONT WILL STALL OUT OVER CENTRAL VIRGINIA AND SOUTHERN MARYLAND TONIGHT. THE FRONT WILL LINGER OVER THE REGION THROUGH THE WEEKEND...WITH SEVERAL WAVES OF LOW PRESSURE MOVING EAST ALONG IT. HIGH PRESSURE WILL RETURN FOR THE FIRST PART OF NEXT WEEK. && .NEAR TERM /THROUGH THURSDAY/... A BOUNDARY IS SLOWLY PUSHING THROUGH THE SOUTHERN SUBURBS OF DC INTO SOUTHERN MARYLAND AND CENTRAL VIRGINIA THIS EVENING. CONVECTION THAT HAS DEVELOPED ALONG THIS BOUNDARY HAS TRAINED OVER THE SAME AREAS...RESULTING IN HEAVY RAIN FOR A SMALL AREA JUST SOUTH OF THE DISTRICT...INCLUDING ALEXANDRIA AND PORTIONS OF PRINCE GEORGES AND FAIRFAX COUNTIES. THE BOUNDARY HAS SLOWLY SLID OFF TO THE SOUTH SO CONVECTION WILL CONTINUE TO DISSIPATE ACROSS THESE AREAS. THE BOUNDARY WILL STALL OUT OVER SOUTHERN MARYLAND INTO CENTRAL VIRGINIA LATE TONIGHT. SHORTWAVE ENERGY WILL ALSO PASS THROUGH THESE AREAS LATE TONIGHT IN THE SOUTHWEST FLOW ALOFT. LEFT POPS IN FOR A FEW SHOWERS ACROSS THESE AREAS...BUT COVERAGE SHOULD REMAIN ISOLATED TO WIDELY SCATTERED DUE TO THE LOSS OF DAYTIME HEATING AND LIMITED INSTABILITY. ELSEWHERE...DRY CONDITIONS ARE EXPECTED OVERNIGHT. THE BOUNDARY WILL REMAIN NEARLY STATIONARY THURSDAY. THIS WILL KEEP A CHANCE FOR SHOWERS/ISOLATED STORMS ESPECIALLY OVER CENTRAL AND SOUTHERN LOCALES DURING THE DAY. HIGH TEMPERATURES WILL BE SLIGHTLY COOLER DURING THE AFTERNOON WITH READINGS IN THE UPPER 70S WEST TO LOW- MID 80S EAST. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... UNCERTAINTY REMAINS WITH REGARDS TO WX LATE THU THROUGH SAT MORNING...AS SUBTLE TO CONSIDERABLE (DEPENDING ON WHICH GUIDANCE YOU CHOOSE) DIFFERENCES EXIST AMONG GUIDANCE WITH REGARDS TO TRACK AND TIMING OF LP SYSTEMS TRACKING ALONG FRONTAL BOUNDARY. MADE NO SIGNIFICANT CHANGES TO GOING FORECAST...WITH CHCS FOR OVERNIGHT SHOWERS LATE THU AND TSTM CHCS FRI AFTN THROUGH THE EVENING. INSTABILITY/SHEAR PROFILES RATHER ANEMIC...AND H5 WINDS AOB 20 KTS...SUGGEST ANY CONVECTIVE ACTIVITY WOULD BE DISORGANIZED. TEMPS APPEAR TO REMAIN REASONABLE WITH M/U 70S THROUGHOUT MUCH OF CWA. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... SERIES OF SHORTWAVES CROSSING REGION OVER THE WEEKEND FOLLOWED BY A BRIEF PERIOD OF RIDGING MONDAY. ON TUESDAY AN UPPER LOW WILL DEVELOP OFF THE DELMARVA COAST WHILE A SHORTWAVE ON THE NORTHERN TRACK PASSES NORTH OF THE REGION. WEAK TO MODERATE PVA WILL AFFECT THE AREA TUESDAY NIGHT. SERIES OF WAVES WILL TRACK ALONG QUASI- STATIONARY FRONT LAYING ACROSS THE MID ATLANTIC REGION THROUGH THE PERIOD. A COLD FRONT WILL APPROACH THE REGION TUESDAY EVENING. ADDITIONAL SHOWER AND THUNDERSTORM DEVELOPMENT MAY BE POSSIBLE. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... MOSTLY VFR THROUGH THURSDAY. THERE MAY BE A PERIOD OF MVFR VSBYS LATE TONIGHT INTO EARLY THURSDAY MORNING FROM BR. ADDITIONAL CHANCES FOR SCATTERED SHOWERS/STORMS ON THURSDAY...MAINLY DURING THE AFTERNOON AND EVENING. MAIN AVIATION CONCERNS THU NIGHT THROUGH FRI REMAIN CHCS FOR SHOWERS AND TSTMS...WITH SUB-VFR CONDITIONS POSSIBLE. HOWEVER...ATTM IT IS DIFFICULT TO DETERMINE EXACT SPATIOTEMPORAL EXTENT OF THIS ACTIVITY. VFR CONDS EXPECTED OUTSIDE OF ANY SHOWER/TSTM ACTIVITY. POTENTIAL EXISTS FOR ADDITIONAL SHOWER AND THUNDERSTORM COVERAGE OVER THE WEEKEND. && .MARINE... WINDS WILL REMAIN BELOW SCA CRITERIA INTO THURSDAY. A FEW SHOWERS/ISOLATED THUNDERSTORMS MAY IMPACT THE MIDDLE PORTION OF THE BAY AND LOWER TIDAL POTOMAC RIVER...ESPECIALLY LATE THIS EVENING. ADDITIONAL CONVECTION IS POSSIBLE THURSDAY...ESPECIALLY DURING THE AFTERNOON AND EVENING. MAIN MARINE CONCERNS THU NIGHT THROUGH FRI WOULD BE WITH ANY TSTM ACTIVITY...AS WINDS APPEAR TO REMAIN BELOW SCA CRITERIA IN THE LIGHT (AOB 10 KTS) AND VARIABLE FLOW. ADDITIONAL SHOWERS AND THUNDERSTORMS COULD IMPACT THE WATERS OVER THE WEEKEND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...KRW NEAR TERM...BJL/KRW SHORT TERM...MSE LONG TERM...CEM AVIATION...BJL/CEM/MSE/KRW MARINE...BJL/CEM/MSE/KRW

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