Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 240118 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 918 PM EDT SUN AUG 23 2015 .SYNOPSIS... HIGH PRESSURE WILL WEAKEN OVER THE AREA TONIGHT. A COLD FRONT WILL APPROACH FROM THE WEST EARLY MONDAY AND CROSS THE REGION BY LATE MONDAY NIGHT. HIGH PRESSURE WILL GRADUALLY BUILD SOUTHEASTWARD INTO THE AREA DURING THE MIDDLE OF THE WEEK AND SETTLE DIRECTLY ON TOP OF OUR AREA FOR THE START OF NEXT WEEKEND. && .NEAR TERM /THROUGH MONDAY/... A FEW SHRA HV MANAGED TO SNEAK INTO THE SWRN CORNER OF THE CWFA... INVOF A TROF AXIS. WITH THE LOSS OF DAYTIME HEATING BELIEVE THE LIFESPAN OF THIS ACTIVITY WL BE LIMITED...AND AM ENDING POPS W OF CHO AND BEFORE MIDNGT. HWVR...A PD OF CLDS WL BE TRACKING ACRS AREA TNGT. ALTHO THE CLDS WL INTERFERE W/ FOG DVLPMNT...THE WV WL ALSO INCH DEWPTS UPWD. MIN-T FCST MAINLY ON TRACK. INITIALLY DRY CONDITIONS MON MORNING WITH 12Z MODEL CONSENSUS SHOWING COLD FRONT GENERALLY EXTENDING THROUGH CENTRAL WV AT 12Z MON. A WEAK WARM FRONT IS NOTED ON THE LATEST RUNS EXTENDING THROUGH CENTRAL VA...WITH PSBL MORNING DEVELOPMENT TO THE SOUTH AND WEST. INCRSG CHC AND COVERAGE OF SHOWERS AND TSTMS INTO THE AFTN AS THE COLD FRONT SWINGS THRU. AXIS OF INSTABILITY LINING UP EAST OF THE BLUE RIDGE MON AFTN INTO THE EVENING WITH MOISTURE ADVECTION ON THE CONTINUAL SLY FLOW AIDING IN PUSHING SBCAPE VALUES TO AROUND 1000 J/KG. OVERALL NOT EXPECTING MUCH IN TERMS OF ORGANIZED CONVECTION WITH LACK OF MID/UPPER LVL FORCING. AS SUCH...EXPECTING FORMATION RIGHT ALONG THE FRONTAL BOUNDARY. && .SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/... COLD FRONT PUSHES THROUGH BY MON EVENING...WITH PCPN TAPERING OFF FROM THE WEST. NOT EXPECTING THE FRONT TO COMPLETELY CLEAR THE REGION AS ASSOCIATED CLOSED LOW LINGERS OVER THE GREAT LAKES REGION...THUS RESULTING IN THE NEAR STALLING OF THE BOUNDARY. THIS COULD KEEP PSBL SHOWERS OVER THE FAR EASTERN PORTIONS OF THE CWA THRU LATE MON NIGHT. HOWEVER...THE DRIER AIR WILL BE QUICK TO MOVE IN...WITH DEW PTS IN THE LOWER 50S ADVECTING IN BY TUES MORNING. COLD FRONT WILL CONTINUE SLOWLY SLIDING SOUTHEAST AWAY FROM THE AREA TUESDAY AND WEDNESDAY AS HIGH PRESSURE TRIES TO NOSE INTO THE AREA FROM THE WEST. TEMPERATURES WILL REMAIN SEASONABLE WITH HIGHS IN THE 80S WIDESPREAD. HOWEVER...DEW POINTS WILL DROP INTO THE LOW- MID 50S TUESDAY AND REMAIN THERE WEDNESDAY ACROSS THE BULK OF THE AREA. A TROUGH WILL BE LOCATED OVER OUR AREA ALOFT WITH A CLOSED LOW WELL TO OUR NORTH IN SOUTHERN CANADA. WILL NEED TO KEEP AN EYE ON PASSING VORT LOBES TO SEE IF A STRAY SHOWER MIGHT TRY TO DEVELOP WITH ONE OF THEM...BUT THE AIR MASS WILL PROBABLY BE DRY ENOUGH TO RETARD ANY SHOWER DEVELOPMENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... HIGH PRESS CONTINUES TO DOMINATE DURING THIS PERIOD KEEPING DRY CONDITIONS OVER OUR REGION. HIGH TEMPS WILL BE GRADUALLY INCREASING FROM THE UPR 70S TO LOW 80S ON THU TO THE MID 80S TO LOW 90S ON SUN. LOWS TEMPS WILL BE IN THE 50S TO UPR 60S. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... GENERALLY VFR CONDITIONS THRU THE TAF PERIOD. IF THERE WERE TO BE AN EXCEPTION...IT WUD TAKE PLACE AT CHO. HV A FEW HRS OF MVFR CONDS TO ACCOUNT FOR IT. A COLD FRONT WILL SWING THRU MON AFTN-EVENING...BRINGING A CHC FOR SHOWERS AND TSTMS. PSBL SUB-VFR CONDITIONS WITH ANY STORM. HWVR...TEMPORAL AND SPATIAL UNCERTAINTIES PRECLUDE A TAF MENTION ATTM. WINDS SLY AHEAD OF THE FRONT WILL BECOME NW BY MON NIGHT. WITH HIGH PRESSURE EXPECTED TO BUILD IN TUESDAY AND PERSIST THROUGH THE LONG TERM...VFR CONDITIONS WITH LIGHT WINDS SHOULD PREVAIL. && .MARINE... SUB-SCA CONDITIONS THRU MON MORNING. HAVE ISSUED A SCA FOR THE CHESAPEAKE BAY WATERS AND LOWER TIDAL POTOMAC MON AFTN-NIGHT TO ACCOUNT FOR INCRSG SLY FLOW AHEAD OF THE FRONT...AS WELL AS A PRESSURE SURGE RESULTING IN ELEVATED WINDS MON NIGHT. WITH HIGH PRESSURE EXPECTED TO DOMINATE TUESDAY NIGHT ONWARD... SUB-SCA CONDITIONS SHOULD PREVAIL THROUGH THE LONG TERM. && .TIDES/COASTAL FLOODING... PERSISTENT SOUTHERLY FLOW WILL LEND TO INCREASED ANOMALIES THROUGH MONDAY NIGHT. TIDAL DEPARTURES RUNNING NEAR 2/3RDS OF A FOOT ABV ASTRO NORMS ATTM...ON TRACK WITH PROJECTIONS. GENERALLY EXPECTING FORECAST SITES TO REMAIN BELOW MINOR FLOOD LEVELS...BUT THERE IS THE POTENTIAL THAT ANNAPOLIS COULD REACH THE MINOR FLOOD THRESHOLD WITH THE HIGH TIDE CYCLE MONDAY NIGHT. WITH THE WIND SHIFT WITH THE COLD FROPA...THIS WOULD BE THE ONLY PROBLEMATIC CYCLE. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 6 PM MONDAY TO 1 AM EDT TUESDAY FOR ANZ531-541-543. SMALL CRAFT ADVISORY FROM 3 PM MONDAY TO 6 AM EDT TUESDAY FOR ANZ533-534-537. SMALL CRAFT ADVISORY FROM 3 PM MONDAY TO 1 AM EDT TUESDAY FOR ANZ532. && $$ SYNOPSIS...RCM NEAR TERM...HTS/SEARS SHORT TERM...SEARS/RCM LONG TERM...IMR/RCM AVIATION...HTS/SEARS/RCM/IMR MARINE...SEARS/IMR/RCM TIDES/COASTAL FLOODING...SEARS/HTS

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