Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --
000 FXUS61 KLWX 021915 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 315 PM EDT TUE SEP 2 2014 .SYNOPSIS... BERMUDA HIGH WILL PERSIST THIS AFTERNOON AHEAD OF A WEAK COLD FRONT THAT WILL CROSS THE AREA TONIGHT. HIGH PRESSURE WILL THEN BUILD FROM THE MIDWEST THROUGH WEDNESDAY THEN PERSIST OFFSHORE THURSDAY INTO THE WEEKEND. A COLD FRONT WILL ENTER THE REGION IN THE SATURDAY NIGHT TIME FRAME. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... VERY WARM AND MOIST AIR MASS PERSISTED OVER THE MID-ATLANTIC THIS AFTERNOON. TEMPERATURES WERE RISING INTO THE LOWER 90S IN MANY AREAS AND THE COMBINATION OF HEAT AND HUMIDITY WAS MAKING IT FEEL MORE LIKE THE MID TO UPPER 90S EAST OF THE BLUE RIDGE. HEAT AND HUMIDITY WILL HELP TO FUEL THUNDERSTORMS THIS AFTERNOON INTO THIS EVENING. WE HAVE SEEN CUMULUS DEVELOPMENT ALREADY...ALTHOUGH CU HAVE HAD LIMITED VERTICAL GROWTH THUS FAR DUE TO SOME CAPPING. THIS IS EXPECTED TO CHANGE LATER THIS AFTERNOON INTO THE EVENING. WE WILL HAVE TO WATCH CONVECTION THAT MAY DEVELOP NEAR A SURFACE TROUGH THIS AFTERNOON. THERE/S ALSO UPSTREAM CONVECTION IN CENTRAL WV /CONVECTION WHICH RE-FIRED/INTENSIFIED FROM EARLY MORNING OHIO VALLEY CONVECTION/ WHICH WILL MOVE EAST WITH TIME...AND THERE COULD ALSO BE ADDITIONAL UPSTREAM CONVECTION LATER ON MORE DIRECTLY ALONG/AHEAD OF THE COLD FRONT. THUS THERE MAY BE SEVERAL CLUSTERS OF CONVECTION TO KEEP AN EYE ON THROUGH THIS EVENING. HOWEVER...DETAILS REGARDING THE EXACT EVOLUTION AND COVERAGE OF ANY ONE REMAIN SOMEWHAT UNCERTAIN. BASED ON RADAR TRENDS...WILL HAVE LIKELY POPS ACROSS THE NORTHWEST PORTION OF THE CWA. FURTHER DOWNSTREAM...WILL KEEP POPS IN THE CHANCE/SCATTERED CATEGORY BUT THESE MAY NEED TO BE BUMPED UP IF ANY ONE CLUSTER CONGEALS AS IT MOVES EAST EITHER LATER THIS AFTERNOON OR THIS EVENING. MODIFIED 12Z KIAD RAOB INDICATED AROUND 3000 J/KG OF CAPE. PRECIPITABLE WATER VALUE WAS AROUND 1.8 INCHES...THIS MAY BE CLOSER TO 2 INCHES BY 00Z. INSTABILITY AND MOISTURE WILL BE DECENT...HOWEVER BETTER SHEAR LIKELY RESIDES JUST NORTHWEST OF THE CWA. THIS MAY LIMIT A WIDESPREAD SEVERE RISK...HOWEVER BUOYANCY ALONE COULD FOSTER A FEW THUNDERSTORMS PRODUCING DAMAGING WIND GUSTS THROUGH THIS EVENING. GIVEN HIGH MOISTURE CONTENT...HEAVY RAINFALL WILL ALSO OCCUR IN THE STRONGEST STORMS. BUT GIVEN FORECAST STORM MOTION...STORMS SHOULD MOVE ENOUGH TO PRECLUDE A FLASH FLOODING RISK UNLESS TRAINING WERE TO OCCUR. COLD FRONT EVENTUALLY CATCHES UP TO THE TROUGH LATER THIS EVENING...MOVING OFFSHORE TONIGHT. CHANCE OF THUNDERSTORMS WILL END BEHIND THE COLD FRONT. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... CWA WILL BE POST-FRONTAL ON WEDNESDAY. NORTHWEST WINDS WILL BRING SOME DRYING THROUGH THE CWA...LEADING TO PLENTY OF SUNSHINE AND LOWER HUMIDITY. FRONT LOOKS LIKE IT GETS HUNG UP IN SOUTHERN VIRGINIA AS WEAK HIGH PRESSURE BUILDS IN FROM THE NORTH. HIGH MOVES OFFSHORE ON THURSDAY. MAY SEE ISOLATED SHOWERS AND THUNDERSTORMS DEVELOP UP/NEAR THE BLUE RIDGE BY AFTERNOON. ACTIVITY WOULD LIKELY BE DIURNAL IN NATURE. TROUGH DEVELOPS ON FRIDAY...WITH THE POTENTIAL FOR MORE DIURNAL CONVECTION. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... ANOTHER COLD FRONT APPROACHES FRIDAY NIGHT. QUESTION IS HOW QUICKLY THE FRONT PUSHES THROUGH THE AREA. IT MAY MOVE THROUGH BY SATURDAY NIGHT...BUT ITS POSSIBLE IT DOESN/T CLEAR THE SOUTHEAST PART OF THE CWA UNTIL SUNDAY. HIGH PRESSURE AND DRY AIRMASS WILL BUILD INTO THE AREA MONDAY. && .AVIATION /19Z TUESDAY THROUGH SUNDAY/... MAIN ISSUE REVOLVES AROUND AFTERNOON AND EVENING CONVECTION. FOCUSED ON LATE AFTERNOON INTO THE EVENING FOR THE HUBS MAINLY BASED ON UPSTREAM CONVECTION OVER WV AND AHEAD OF THE COLD FRONT...ALTHOUGH ISOLATED TSRA AHEAD OF THESE CAN NOT BE RULED OUT EARLIER. COLD FRONT MOVES THROUGH LATE IN THE EVENING WITH A WIND SHIFT TO THE NORTHWEST. LOW LEVEL MOISTURE LINGERS TONIGHT. IF WINDS BECOME CALM...FOG MAY FORM. THIS APPEARS MOST LIKELY AT CHO. EXPECTATION IS FOR ENOUGH WIND TO OCCUR AT OTHER SITES TO INHIBIT FOG FORMATION. VFR EXPECTED WEDNESDAY POST-FRONTAL AND WITH HIGH PRESSURE IN CONTROL. HIGH MOVES OFFSHORE TO END THE WEEK. NEXT COLD FRONT WILL AFFECT THE AREA OVER THE WEEKEND. && .MARINE... PRIMARY CONCERN LATE THIS AFTERNOON AND EVENING WILL BE STRONG GUSTY WINDS AND LIGHTNING IN SCATTERED SHOWERS AND THUNDERSTORMS. SMW/S MAY BECOME NECESSARY. CHANCE OF THUNDERSTORMS WILL CONTINUE UNTIL A COLD FRONT PASSES TONIGHT. HIGH PRESSURE BUILDS IN FOR WEDNESDAY THEN MOVES OFFSHORE TO END THE WEEK. COLD FRONT MOVES THROUGH OVER THE WEEKEND. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...BPP NEAR TERM...BPP SHORT TERM...BPP LONG TERM...CEM AVIATION...BPP/CEM MARINE...BPP/CEM

USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.