Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 010743 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 343 AM EDT FRI MAY 1 2015 .SYNOPSIS... LOW PRESSURE WILL MOVE AWAY FROM THE AREA TODAY...BUT AN UPPER- LEVEL TROUGH WILL REMAIN OVERHEAD. HIGH PRESSURE WILL BUILD OVERHEAD TONIGHT THROUGH SATURDAY NIGHT BEFORE DROPPING TO OUR SOUTH EARLY NEXT WEEK. A COLD FRONT MAY IMPACT THE AREA DURING THE MIDDLE PORTION OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... LIGHT TO PERIODS OF MODERATE PCPN ON GOING EARLY THIS MORNING AS AN UPPER LVL TROUGH DIGS SOUTH...WITH A POTENT SHORTWAVE PIVOTING ACROSS THE MID ATLANTIC. 07Z WATER VAPOR IMAGERY SHOWING DEEPENING SFC LOW OVER THE CAROLINAS INTERACTING WITH THE TROUGH ALOFT. THE AXIS UPON WHICH THE PCPN IS ROTATING SPLITS THE CWA...WITH EASTERLY INFLUENCE FROM THE LOW OVERSPREADING PCPN OVER EASTERN AREAS...MAINLY EAST OF THE BLUE RIDGE...WHILE THE DIGGING SHORTWAVE IS PRODUCING PCPN TO THE WEST OF THE BLUE RIDGE. SOME QUESTION REMAINS AS TO HOW FAR NORTH THE PCPN WOULD REACH/PIVOT...WITH MOST OF THE MESO MODELS INDICATING THE BULK OF THE PCPN BEING SUPPRESSED SOUTH OF THE MASON-DIXON LINE...CLOSER TO CENTRAL VA THIS MORNING AS THE SFC LOW SLOWLY PUSHES MORE EAST THAN NORTH AND THE SHORTWAVE CONTINUES TO PIVOT TO THE SOUTH AND EAST. BY THIS AFTN...THE SFC LOW IS OFF THE CAROLINA COAST...WITH HIGH PRESSURE TO THE WEST. EASTERN PORTIONS OF THE CWA COULD SEE PCPN THIS AFTN...TAPERING OFF BY THIS EVENING AS THE LOW PULLS AWAY. THE BETTER CHC FOR AFTN ACTIVITY WILL BE SHOWERS OVER WESTERN AREAS WITH A UPSLOPE COMPONENT AS WINDS BACK TO THE NW. HAVE KEPT MENTION OF THUNDER OUT AT THIS TIME WITH MINIMAL INSTABILITY AND SHEAR. PCPN ENDS BY THE SECOND HALF OF TONIGHT WITH THE SFC HIGH BUILDING IN FROM THE WEST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... HIGH PRESSURE CENTERED OVER KY BY 12Z SAT MORNING WILL BUILD EAST THROUGH THE WEEKEND. WHILE MOST OF THE WEEKEND WILL REMAIN DRY...DID CONTINUE TO MENTION A SLIGHT CHC OF SHOWERS FOR SAT AFTN EAST OF THE BLUE RIDGE AS ANOTHER SHORTWAVE SLIDES SOUTH THROUGH THE MID ATLANTIC. WHILE INSTABILITY IS ONCE AGAIN ON THE MINIMAL SIDE...SHEAR IS A BIT STRONGER AND WITH ENOUGH FORCING ALOFT...COULD SEE A BRIEF SHOWER POP UP. ANY CHC OF PCPN WILL END BY SAT EVENING WITH THE LOSS OF DAYTIME HEATING. TEMPS WILL HOVER NEAR NORMAL ON SAT. WITH RISING HEIGHTS BY SAT NIGHT...EXPECTING A WARM UP FOR THE SECOND HALF OF THE WEEKEND HEADING INTO THE NEW WORK WEEK. TEMPS WILL BE ABV NORMAL...WITH SOME SPOTS POTENTIALLY TOUCHING 80 ON SUNDAY UNDER MOSTLY SUNNY SKIES. && .LONG TERM /MONDAY THROUGH THURSDAY/... HIGH PRESSURE WILL REMAIN TO OUR SOUTH MONDAY THROUGH TUESDAY AND A SOUTHWEST FLOW AROUND THIS SYSTEM WILL USHER IN NOTICEABLY WARMER CONDITONS. MAX TEMPS WILL REACH THE 80S FOR MOST LOCATIONS. MONDAY WILL BE DRY...BUT A COLD FRONT WILL APPROACH FROM THE NORTH TUESDAY AND A FEW SHOWERS/THUNDERSTORMS CANNOT BE RULED OUT DURING THE AFTERNOON AND EVENING HOURS ACROSS THE NORTHERN PORTION OF THE CWA. THE COLD FRONT WILL MOVE INTO THE REGION WEDNESDAY BEFORE STALLING OUT OVERHEAD ON THURSDAY. THE BOUNDARY MAY TRIGGER A FEW SHOWERS AND THUNDERSTORMS WEDNESDAY...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. HOWEVER...WARM CONDITIONS WILL PERSIST AND MUCH OF THE TIME WILL BE DRY. SAME GOES FOR THURSDAY...DEPENDING ON EXACTLY WHERE THE BOUNDARY STALLS OUT. PERHAPS A BETTER CHANCE FOR CONVECTION WILL BE ACROSS THE WESTERN CWA WITH MARINE AIR KEEPING THE ATMOSPHERE MORE STABLE FARTHER EAST BEHIND THE STALLED BOUNDARY. && .AVIATION /07Z FRIDAY THROUGH TUESDAY/... VARYING CONDITIONS THIS MORNING AS LIGHT RAIN MOVES ACROSS THE AREA AND PATCHY FOG IS DEVELOPING. THRU 12Z...EXPECTING CIGS AND VIS TO CONTINUE TO DIMINISH. LOW-MOD CONFIDENCE ON THE CIGS REACHING IFR LVLS...WITH THE BETTER CHC OF STAYING MVFR. VIS SHOULD REMAIN VFR AT THE DC-BALTIMORE TAF SITES...WITH FOG DROPPING VIS DOWN TO 2-4SM FOR KCHO AND KMRB. CONDITIONS EXPECTED TO IMPROVE AFTR 12Z...THOUGH COULD SEE IMPROVEMENT OFF 1-2 HRS THAN IN THE TAFS. LIGHT RAIN SHOWERS PSBL...MAINLY KDCA/KIAD/KCHO...11-14Z...BUT WITH MINIMAL IMPACT ON CATEGORICAL CONDITIONS. KMRB MAY SEE AN ISO SHOWER THIS AFTN...BUT TOO LOW OF CONFIDENCE TO INCLUDE IN TAF ATTM. VFR CONDITIONS THIS AFTN THRU SUN NIGHT. NE WINDS AROUND 10 KTS TODAY BCMG LIGHT AND VRB TONIGHT. WINDS REMAIN LIGHT THRU THE WEEKEND...WHILE SHIFTING FROM THE NW ON SAT TO THE S BY SAT NIGHT. VFR CONDITIONS ARE EXPECTED FOR MONDAY AND TUESDAY WITH SOUTHWEST FLOW. A SHOWER OR THUNDERSTORM CANNOT BE RULED OUT TUESDAY AFTERNOON AND EVENING ACROSS THE NORTHERN TERMINALS. && .MARINE... SCA REMAINS IN EFFECT FOR ALL WATERS THROUGH THIS MORNING...WITH THE NORTHERN CHESAPEAKE BAY AND TIDAL POTOMAC BEING DROPPED FOR THE AFTN. WINDS ARE STRUGGLING TO REACH CRITERIA LVLS EARLY THIS MORNING...BUT AS THE COASTAL LOW DEEPENS AND PUSHES NORTH...EXPECTING THE NELY FLOW TO INCREASE...MAINLY BY 12Z. AS SUCH...WILL LEAVE THE ADVISORY AS IS. WINDS EXPECTED TO DIMINISH EVERYWHERE BY LATE AFTN TO SUB-SCA LVLS SO WILL NOT EXPAND THE SCA. HIGH PRESSURE BUILDING ACROSS THE REGION WILL KEEP SUB-SCA CONDITIONS IN PLACE ACROSS ALL WATERS TONIGHT THRU SUN NIGHT. HIGH PRESSURE WILL REMAIN TO THE SOUTH MONDAY THROUGH TUESDAY. A SOUTHWEST FLOW IS EXPECTED DURING THIS TIME. WIND GUSTS MAY APPROACH SCA CRITERIA FOR PORTIONS OF THE WATERS MONDAY NIGHT THROUGH TUESDAY NIGHT. A COLD FRONT WILL APPROACH FROM THE NORTH TUESDAY. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE DURING THE AFTERNOON AND EVENING HOURS...ESPECIALLY ACROSS THE NORTHERN PORTIONS OF THE WATERS. MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE WEDNESDAY...ESPECIALLY DURING THE AFTERNOON AND EVENING HOURS. && .TIDES/COASTAL FLOODING... A NORTHEAST FLOW HAS CAUSED TIDAL ANOMALIES TO INCREASE TO AROUND ONE-HALF TO THREE QUARTERS OF A FOOT ABOVE NORMAL ACROSS THE CHESAPEAKE BAY. THE NORTHEAST WINDS WILL CONTINUE TODAY THROUGH TONIGHT...LIKELY KEEPING WATER LEVELS ELEVATED ACROSS THE BAY AND EVEN THE TIDAL POTOMAC RIVER. MINOR TIDAL FLOODING IS NOT EXPECTED THROUGH TODAY SINCE THE NEXT HIGH TIDE WILL BE THE LOWER OF THE TWO. THE ANOMALIES SHOULD HOLD OR PERHAPS EVEN INCREASE A BIT THROUGH TONIGHT. IF THIS OCCURS...THEN WATER LEVELS MAY COME CLOSE TO MINOR FLOODING THRESHOLDS DURING THE HIGH TIDE CYCLE LATE TONIGHT INTO EARLY SATURDAY. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR ANZ530-531-535- 538-539. SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS EVENING FOR ANZ532>534-536-537-540>543. && $$ SYNOPSIS...BJL NEAR TERM...SEARS SHORT TERM...SEARS LONG TERM...BJL/SEARS AVIATION...BJL/SEARS MARINE...BJL/SEARS TIDES/COASTAL FLOODING...BJL

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