Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 310250 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1050 PM EDT WED JUL 30 2014 .SYNOPSIS... SURFACE HIGH PRESSURE PERSISTS OVER THE MID-ATLANTIC. UPPER LEVEL LOW PRESSURE OVER EASTERN ONTARIO CONTINUES TO SPIN COOL AIR INTO THE REGION. A COASTAL FRONT WILL DEVELOP THIS WEEKEND AND LAST INTO EARLY NEXT WEEK. && .NEAR TERM /TONIGHT/... AS EXPECTED...ONLY A FEW SHRA REMAIN CLOSE TO THE MASON-DIXON LINE. POPS HAVE BEEN LOWERED ACCORDINGLY FOR THE REST OF THE NIGHT. NO CHANGE IN TEMPS...BUT DID RAISE SKY COVER AS MID CLOUDS ADVECT ACROSS THE REGION. EXPECT THESE TO AT LEAST PARTIALLY CLEAR TOWARD DAYBREAK...WHICH COULD ALLOW SOME FOG TO DEVELOP IN THE SHENANDOAH VALLEY. LEFT TEMPERATURES AS IS...BUT WINDS WILL NEED TO GO NEARLY CALM FOR THE FORECAST TO BE REALIZED. THIS IS WHAT IS EXPECTED EXCEPT IN THE CITIES AND HGIHER ELEVATIONS...WHERE LOWS WERE RAISED IN AN EARLIER UPDATE. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... HIGH PRESSURE MOVES FURTHER OFFSHORE THURSDAY...WITH RETURN FLOW OVER THE REGION. NOT EXPECTING ANY NOTABLE LIFTING MECHANISMS OVER THE REGION...SO DRY WEATHER LIKELY FOR MOST. SOME TERRAIN CIRCULATION TSTM ACTIVITY POSSIBLE IN THE HIGHLANDS. TEMPS REBOUND BACK INTO THE 80S FOR MOST AREAS...INCLUDING POSSIBLY THE UPPER 80S IN SOME URBAN LOCATIONS. A MORE UNSETTLED PATTERN SETS UP THURSDAY NIGHT THROUGH SATURDAY. 500MB TROUGH OVER THE OHIO VALLEY STRENGTHENS. AN OFFSHORE STATIONARY FRONT MAY RETROGRADE WESTWARD...WITH A WAVE OF LOW PRESSURE DEVELOPING ALONG IT BY FRIDAY NIGHT. PERIODS OF SHOWERS AND TSTMS WILL BE POSSIBLE THU NIGHT THROUGH SATURDAY. DAYTIME TEMPS FRIDAY AND SATURDAY SHOULD HOLD IN THE LOW 80S DUE TO CLOUD COVER. LOW TEMPS SHOULD BE NEAR NORMAL. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... UPPER LEVEL TROUGH OVER THE GREAT LAKES/MISSISSIPPI VALLEY WILL SLOWLY FILL AND SHIFT OFF ATLANTIC COAST BY SATURDAY AFTERNOON. SURFACE LOW PRESSURE TROUGH ALONG THE ATLANTIC COAST...PVA ASSOCIATED WITH 500MB TROUGH OVER THE OHIO VALLEY AND MOISTURE BROUGHT INTO THE CWA BY SOUTH/SOUTHWEST WINDS ASSOCIATED WITH BERMUDA RIDGE WILL SUPPORT DEVELOPMENT OF SHOWERS/THUNDERSTORMS SATURDAY AND SUNDAY. NOT SO MUCH MONDAY AND TUESDAY WHEN DRY AIRMASS ASSOCIATED WITH HIGH PRESSURE CENTERED OVER THE MIDWEST BUILDS INTO CWA. CHANCES OF PRECIPITATION LOOK TO INCREASE AGAIN AT MIDWEEK WHEN A COLD FRONT FROM GREAT LAKES APPROACHES. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... VFR CONDITIONS EXPECTED THROUGH TONIGHT...EXCEPT AT KCHO AND PERHAPS KMRB WHERE A BRIEF PERIOD OF MVFR FOG IS POSSIBLE EARLY THURSDAY MORNING. LIGHT S-SW FLOW EXPECTED THROUGH THURSDAY AFTERNOON. PERIODS OF SHOWERS OR TSTMS POSSIBLE FRIDAY THROUGH EARLY NEXT WEEK...BUT VFR CONDITIONS LIKELY IN BETWEEN ANY SHRA/TSRA. && .MARINE... WINDS GENERALLY 10KT AND LESS OVER THE WATERS THIS EVENING. LLJ IS EXPECTED TO DEVELOP TONIGHT WITH 15-20KT S-SW WINDS ALOFT. NOT EXPECTING THIS TO GUST DOWN AT THIS TIME AS THE INVERSION SETS UP OVERNIGHT...BUT WILL KEEP AN EYE ON IT. SOUTHERLY WINDS EXPECTED AGAIN THURSDAY. NO SCA EXPECTED...BUT SOME GUSTS IN THE TEENS POSSIBLE NEAR THE CONFLUENCE OF THE TIDAL POTOMAC AND CHES BAY. SOUTHEASTERLY WINDS FRIDAY THROUGH SUNDAY WITH LARGE HIGH PRESSURE IN THE WRN ATLANTIC...BUT CLOSE ENOUGH TO KEEP WINDS FAIRLY LIGHT. PERIODS OF SHRA/TSRA POSSIBLE EACH DAY. && .CLIMATE... CHILLY MORNING WITH A RECORD LOW OF 48 AT DULLES. THIS IS THE COOLEST MORNING LOW IN JULY SINCE JULY 12TH 2002. NOT TO BE OUTDONE...EVEN IN THE URBAN CENTER...THE MORNING LOW OF 60 AT REAGAN WAS THE COOLEST IN JULY SINCE THAT SAME DATE IN 2002. AT DULLES...WE ARE ON TRACK FOR THE COOLEST JULY SINCE 2001...AND THE YEAR-TO-DATE AVERAGE TEMPERATURE OF 51.5 DEGREES IS THE 5TH COOLEST ON RECORD /DATING BACK TO 1962/. AT BWI...A RECORD LOW WAS SET OF 55 DEGREES...THE COOLEST IN JULY SINCE JULY 3RD 2007. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...KS/JE NEAR TERM...JE SHORT TERM...KS LONG TERM...CEM AVIATION...JE/KS MARINE...JE/KS CLIMATE...JE

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