Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 020755 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 355 AM EDT WED SEP 2 2015 .SYNOPSIS...AN UPPER-LEVEL DISTURBANCE WITH ITS ASSOCIATED SURFACE TROUGH WILL PASS THROUGH THE REGION TODAY. WEAK HIGH PRESSURE WILL BUILD OVERHEAD THURSDAY BEFORE A BACKDOOR COLD FRONT MOVES INTO THE AREA LATE FRIDAY INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/...AN EXPANSIVE AREA OF HIGH PRESSURE PERSISTS ACROSS THE EASTERN CONUS THIS MORNING. A SHORTWAVE TROUGH IS LOCATED ACROSS IN/OH THIS MORNING. A MOISTURE PLUME IS ROUNDING THE TOP OF A 500MB RIDGE LOCATED ACROSS THE SE CONUS. THIN MID-HIGH LEVEL CLOUDS ARE MOVING ACROSS THE MID-ATLANTIC THIS MORNING. WARM AND HUMID CONDITIONS PERSIST WITH DEWPTS IN THE UPPER 60S TO LOW 70S. EVEN WITH CLOUD COVER PATCHY FOG HAS DEVELOPED IN LOW LYING LOCATIONS. FOG IS EXPECTED TO INCREASE IN COVERAGE THIS MORNING AND INTO THE MORNING COMMUTE. SOME BREAKS IN THE CLOUD COVER ARE POSSIBLE THIS MORNING AND WILL AIDE IN FOG DEVELOPMENT. FOG SHOULD DISSPATE SHORTLY AFTER SUNRISE. AN ISOLATED SHOWER MAY POP UP THIS MORNING WEST OF THE BLUE RIDGE AS A SHORTWAVE TROUGH NEARS. THE SHORTWAVE TROUGH WILL MOVE TOWARD WV/VA TODAY. THIS COUPLED WITH TEMPS IN THE LOW TO MID 90S AND ELEVATED DEWPTS WILL RESULT IN SHOWERS AND THUNDERSTORMS BREAKING OUT TODAY. THE REGION OF CONCERN IS WEST OF THE BLUE RIDGE ESPECIALLY THE SW WHERE THE BEST FORCING FROM THE DISTURBANCE WILL BE LOCATED. SEVERE THREAT IS LOW DUE TO THE WEAK FIELD FIELD DUE TO THE UPPER LEVEL RIDGE. HOWEVER...500-1000 J/KG OF ML CAPE IS EXPECTED EVEN WITH SOME CLOUD COVER AND THEREFORE SOME THUNDERSTORMS ARE EXPECTED. FURTHER EAST...A SFC TROUGH WILL FORM AROUND THE I-95 CORRIDOR/CHES BAY. THIS MAY CAUSE A FEW SHOWERS TO POP UP THIS AFTERNOON NEAR THE WATERS. SOME SHOWERS AND THUNDERSTORMS MAY MOVE EAST OF THE BLUE RIDGE DUE TO WEAK SE FLOW ALOFT. COVERAGE IS EXPECTED TO DECREASE AS THEY MOVE EAST TODAY AND AREAS EAST OF THE POTOMAC RIVER MAY STAY DRY ALL DAY. TEMPS IN THE UPPER 80S NEAR AND WEST OF THE BLUE RIDGE AND THE LOW TO MID 90S NEAR I-95 TODAY. THE SHORTWAVE TROUGH WILL DIVE INTO NC TONIGHT AND ACTIVITY WILL MOVE TO THE SOUTH BY MIDNIGHT. DRY CONDITIONS WILL MOVE INTO THE REGION OVERNIGHT HOWEVER DUE TO NO AIRMASS CHANGE...WARM AND HUMID CONDITIONS WILL PERSIST WITH OVERNIGHT TEMPS IN THE 60S/LOW 70S AND MID 70S IN THE METROS. && .SHORT TERM /THURSDAY/...THE SFC TROUGH WILL MOVE EAST THURSDAY AND BE LOCATED ALONG THE EAST COAST. NRLY FLOW IS EXPECTED ACROSS THE REGION. 850MB TEMPS ARE EXPECTED TO INCREASE FROM TUE/WED AND THEREFORE THURSDAY HAS THE POTENTIAL TO BE THE HOTTEST DAY OF THE WEEK. SEVERAL DISTURBANCES WILL BE UPSTREAM AND CLOUD COVER MAY CUT DOWN ON THE TEMPS THURSDAY. A FEW SHOWERS ARE POSSIBLE THURSDAY AFTERNOON MAINLY WEST OF THE BLUE RIDGE. AN ISOLATED THUNDERSTORM IS ALSO POSSIBLE. && .LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...A BACKDOOR COLD FRONT WILL ENTER NORTHEAST MD LATE FRI AND MOVE SWD ACROSS THE REST OF THE AREA FRI NIGHT. SCT SHOWERS AND/OR T-STORMS CAN BE EXPECTED ALONG AND AHEAD OF THE FRONT FRI EVENING WITH ACTIVITY LINGERING LONGER ALONG THE I-64 CORRIDOR AND CHARLOTTESVILLE AREA. HIGH PRESSURE SFC AND ALOFT BUILDS QUICKLY LATE FRI NIGHT THROUGH SUN LEADING TO VERY DRY CONDITIONS AND COOLER TEMPERATURES. WHILE IT IS EXPECTED TO BE SUNNY MUCH OF THE WEEKEND...AEROSOL OPTICAL DEPTH (AOD) OUTPUT FROM THE INTERNATIONAL COOPERATIVE FOR AEROSOL PREDICTION MULTI-MODEL ENSEMBLE (ICAP MME) SHOWS REMNANT SMOKE FROM THE GREAT LAKES REGION GETTING SHUNTED SOUTHEASTWARD INTO THE MID-ATLC FRI INTO THE WEEKEND AS STEERING WINDS BECOME MORE NORTHEASTERLY. SO...POTENTIAL FOR AIR QUALITY ISSUES OVER THE WEEKEND UNDER STAGNANT HIGH PRESSURE SYSTEM. && .AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...SUB-VFR VSBYS POSSIBLE MAINLY AT MRB-CHO-IAD THIS MORNING. CLOUDS SHOULD LIMIT DENSE FOG DEVELOPMENT BUT THE HUMID AIRMASS HAS ALREADY LED TO 3-5SM IN NEARBY LOCATIONS. VFR CONDITIONS EXPECTED TODAY. SHRA/VCTS IS POSSIBLE MAINLY AT MRB-CHO THIS AFTERNOON. SOME ACTIVITY MAY MOVE INTO IAD-DCA BUT CONFIDENCE IS LOW. ACTIVITY WILL MOVE TO THE SOUTH TONIGHT AND SUB-VFR VSBYS DUE TO FOG ARE POSSIBLE AGAIN INTO THURS MORNING. VFR CONDITIONS EXPECTED THURSDAY. BACKDOOR CFDNT WILL CROSS THE AREA FRI NIGHT WITH SHIFTING WINDS. RISK OF SHOWERS AND T-STORMS WILL BE ENDING FROM NORTHEAST TO SOUTHWEST FRI NIGHT. ALSO...POTENTIAL FOR VISBILITY RESTRICTIONS FRI INTO THE WEEKEND AS AEROSOL MODELS SUGGEST SMOKE GETTING SHUNTED SOUTHEASTWARD FROM THE GREAT LKS REGION INTO THE MID-ATLC. BUILDING HIGH PRES SFC AND ALOFT AND STRENGTHENING SUBSIDENCE INVERSION COULD FURTHER COMPLICATE THINGS. && .MARINE...A SFC TROUGH IS EXPECTED TO FORM LATER TODAY AND A FEW SHOWERS MAY POP UP THIS AFTERNOON. WINDS SHOULD STAY LIGHT BELOW 10KTS THROUGH THURSDAY. SFC TROUGH MOVES EAST OF THE WATERS THURSDAY. FRONTAL PASSAGE EXPECTED FRI NIGHT WITH SHIFTING WINDS. WINDS COULD APPROACH SCA CRITERIA FRI AFTERNOON AND SATURDAY. REMNANT SMOKE EXPECTED TO GET TRANSPORTED INTO THE REGION OVER THE WEEKEND COULD RESULT IN VISIBILITY RESTRICTIONS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...LFR NEAR TERM...HAS SHORT TERM...HAS LONG TERM...LFR AVIATION...HAS/LFR MARINE...HAS/LFR

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