Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 251343 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 943 AM EDT FRI JUL 25 2014 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OVER THE REGION THROUGH TONIGHT BEFORE MOVING OFF THE COAST SATURDAY. AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE AREA SUNDAY AND A POTENT COLD FRONT WILL MOVE THROUGH MONDAY. HIGH PRESSURE WILL RETURN FOR THE MIDDLE PORTION OF NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... HIGH PRESSURE IS ACROSS THE AREA THIS MORNING AS DRY ALOFT LEAVES THE MID-ATLANTIC DRY AND CLEAR. VALLEY FOG WILL CONTINUE TO BURN OFF IN THE SHENANDOAH VALLEY AND POTOMAC HIGHLANDS. FCST MAX TEMPS TODAY WILL BELOW CLIMO...UPPER 70S IN THE MTNS AND LOW TO MID 80S NEAR THE I-95 CORRIDOR. PREV DISC.... WINDS WILL TURN SLY AND AGAIN BEGIN THE LOW-LEVEL MOISTURE INCREASE. DEWPOINTS LATER TONIGHT WILL CLIMB BACK INTO THE L60S FROM THE SHEN VLY TOWARD THE EAST OVER TIME. NO SUBSTANTIAL WX- CHANGE FROM THIS RETURN FLOW OVERNIGHT BUT IT WILL SET-UP THE AREA HEADING INTO THE WEEKEND FOR A RETURN TO THE WARMER/HUMID CONDITIONS - AND AN ACTIVE ATMOS TO START THE COMING WEEK. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... HIGH PRESSURE WILL MOVE OUT INTO THE ATLANTIC SATURDAY THROUGH SATURDAY NIGHT. A SOUTHERLY FLOW WILL ALLOW FOR WARMER AND MORE HUMID CONDITIONS TO RETURN. MAX TEMPS SATURDAY WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE UPPER 80S/NEAR 90 IN THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS. THE HEAT AND HUMIDITY WILL LEAD TO AN UNSTABLE ATMOSPHERE SATURDAY AFTERNOON AND EVENING. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE...BUT WITH THE LACK OF A STRONG LIFTING MECHANISM...CONVECTION COVERAGE WILL BE ISOLATED OR WIDELY SCATTERED. A POTENT SHORTWAVE IN THE WESTERLY FLOW ALOFT WILL APPROACH THE AREA SATURDAY NIGHT. MOST OF THE FORCING SHOULD REMAIN TO THE WEST...BUT A SURFACE TROUGH WILL STRENGTHEN A BIT OVER THE AREA. THEREFORE...A FEW SHOWERS AND THUNDERSTORMS WILL REMAIN POSSIBLE SATURDAY NIGHT. MIN TEMPS WILL RANGE FROM THE 60S IN THE MOUNTAINS TO THE MIDDLE 70S IN DOWNTOWN WASHINGTON AND BALTIMORE...AND IT WILL FEEL NOTICEABLY MORE HUMID. && .LONG TERM /SUNDAY THROUGH THURSDAY/... THE POTENT SHORTWAVE WILL PASS THROUGH THE REGION SUNDAY IN THE WESTERLY FLOW ALOFT. THE FORCING FROM THE SHORTWAVE WILL COMBINE WITH SOME INSTABILITY FROM A WARM AND HUMID AIRMASS TO BRING A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS. SHEAR PROFILES DO SUPPORT THE POSSIBILITY OF SEVERE THUNDERSTORMS...BUT THERE IS A QUESTION REGARDING THE COVERAGE BECAUSE PLENTY OF HIGH AND MID- LEVEL CLOUDS MAY LIMIT INSTABILITY. AS OF NOW...THERE IS AT LEAST AN ISOLATED THREAT FOR LOCALLY DAMAGING WIND GUSTS. LOCALLY HEAVY RAINFALL IS MORE LIKELY IN SHOWERS AND THUNDERSTORMS SUNDAY. WITH PWATS OVER 2 INCHES AND THE POSSIBILITY FOR TRAINING CONVECTION...THIS DOES POSE A THREAT FOR FLASH FLOODING. AGAIN...THE EXTENT OF FLASH FLOODING WILL BE DEPENDENT ON HOW MUCH INSTABILITY CAN DEVELOP. THE SHORTWAVE WILL MOVE OFF TO THE EAST SUNDAY NIGHT...BUT AN EVEN STRONGER SHORTWAVE AND ITS ASSOCIATED COLD FRONT WILL APPROACH FROM THE OHIO VALLEY. MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE SUNDAY NIGHT AHEAD OF THIS SYSTEM. THE COLD FRONT WILL PASS THROUGH THE REGION MONDAY...BRINGING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. IF THIS SYSTEM IS SLOW ENOUGH...THEN THERE WILL BE ENOUGH HEATING FOR SEVERE THUNDERSTORMS SINCE SHEAR PROFILES WILL BE EXTREMELY FAVORABLE. DAMAGING WIND GUSTS AND LARGE HAIL WOULD BE THE PRIMARY THREATS. DETAILS ARE STILL UNCERTAIN DUE TO THE HIGH UNCERTAINTY WITH THE TIMING OF THE FRONT. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR THE MIDDLE PORTION OF NEXT WEEK...BRINGING NOTICEABLY COOLER AND DRIER CONDITIONS. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... FEW-SCT CU FIELD EXPECTED TODAY. N WINDS 5-10KTS EXPECTED THIS MORNING AND AFTERNOON...BECOMING SRLY BY EVENING. PATCHY BR IS POSSIBLE SATURDAY MORNING...ESPECIALLY ACROSS THE WESTERN TERMINALS. OTHERWISE...VFR CONDITIONS ARE EXPECTED WITH A SOUTH-SOUTHWEST FLOW. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE SATURDAY AFTERNOON AND SATURDAY NIGHT...BUT COVERAGE WILL BE LIMITED. PATCHY BR IS POSSIBLE OVERNIGHT SATURDAY INTO EARLY SUNDAY. A POTENT UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE TERMINALS SUNDAY INTO SUNDAY EVENING...BRINGING A BETTER CHANCE FOR SHOWERS AND THUNDERSTORMS. THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND LOCALLY HEAVY RAINFALL THAT COULD REDUCE CIGS/VSBYS TO IFR LEVELS AT TIMES. A POTENT COLD FRONT WILL APPROACH THE TERMINALS SUNDAY NIGHT AND PASS THROUGH MONDAY. MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE AHEAD OF THE FRONT. HIGH PRESSURE WILL RETURN FOR TUESDAY WITH A NORTHWEST FLOW. && .MARINE... NORTHERLY WINDS AROUND 10 KTS EXPECTED ON THE WATERS TODAY. SOUTHERLY WINDS ARE EXPECTED AROUND HIGH PRESSURE OVER THE ATLANTIC FOR SATURDAY AND SUNDAY. WINDS MAY GUSTS PAST SCA CRITERIA OVER PORTIONS OF THE WATERS SATURDAY NIGHT INTO SUNDAY. A COLD FRONT WILL PASS THROUGH THE WATERS MONDAY AND NORTHWEST WINDS MAY GUST PAST SCA CRITERIA BEHIND THE FRONT MONDAY NIGHT AND TUESDAY. SHOWERS AND THUNDERSTORMS ARE POSSIBLE SATURDAY THROUGH MONDAY. AS OF NOW...IT APPEARS THAT THE BEST CHANCE FOR THUNDERSTORMS WILL SUNDAY AND MONDAY. THUNDERSTORMS MAY CONTAIN GUSTY WINDS AND LOCALLY HEAVY RAINFALL THAT COULD REDUCE VSBYS BELOW A MILE AT TIMES. && .CLIMATE... 59 DEGREES IS THE FORECAST FOR BWI EARLY THIS MORNING. THE RECORD LOW FOR THE THREADED BALTIMORE CLIMATE RECORD IS 59...SET IN 2008... 1976...1973...AND 1876. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BJL NEAR TERM...HAS/GMS SHORT TERM...BJL LONG TERM...BJL AVIATION...BJL/GMS/HAS MARINE...BJL/GMS/HAS CLIMATE...LWX

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