Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Text Only | 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 301838 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 238 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. THIS WILL GRADUALLY RECEDE AS THE WEEK PROGRESSES. A COASTAL FRONT WILL DEVELOP THIS WEEKEND AND LAST INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... SURFACE HIGH PRESSURE OVER THE REGION LATE THIS AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OVER WESTERN PA AND ACROSS OHIO...AHEAD OF A COLD FRONT ALONG THE GREAT LAKES. ALTHOUGH THE COLD FRONT ITSELF IS EXPECTED TO WEAKEN...AN UPPER TROF IS EXPECTED TO MOVE INTO THE REGION BY THE EVENING ALONG WITH POTENTIAL DEVELOPMENT OF A WEAK SURFACE TROF. SCATTERED SHOWERS AND MAYBE A FEW TSTMS WILL BE POSSIBLE OVER WESTERN PORTIONS OF THE FORECAST AREA LATE THIS AFTERNOON...GENERALLY WEST OF THE BLUE RIDGE. SOME MODELS INDICATE SOME OF THIS ACTIVITY MAY REACH EAST OF THE MOUNTAINS THIS EVENING...BUT KEPT POPS OUT OF THE FORECAST FOR NOW SINCE THE ATMOS OVER THIS AREA IS MORE STABLE. AFTERNOON TEMPS GENERALLY IN THE MID TO UPPER 70S...WITH POTENTIAL FOR A FEW SPOTS TO REACH 80. ANY SHOWER ACTIVITY IS EXPECTED TO DIMINISH BY LATE EVENING. RIDGE AXIS IS EXPECTED TO MOVE OFFSHORE...WITH LIGHT SOUTHERLY FLOW DEVELOPING. DEW POINTS ARE EXPECTED TO RISE ACCORDINGLY INTO THE UPPER 50S TO AROUND 60. SOME VALLEY FOG IS POSSIBLE LATE. LOWS RANGE FROM THE LOW 50S IN HIGHER ELEVATIONS TO THE 60S IN URBAN AREAS AND NEAR THE WATERS. && .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 TUESDAY/... 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 /18Z WEDNESDAY THROUGH MONDAY/... VFR CONDITIONS EXPECTED THROUGH TONIGHT...EXCEPT AT KCHO WHERE 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 LATE THIS AFTERNOON. LLJ IS EXPECTED TO DEVELOP TONIGHT WITH 15-20KT S-SW WINDS ALOFT. NOT EXPECTING THIS TO GUST DOWN AT THIS TIME...BUT WILL NEED TO WATCH IN CASE THE LLJ STRENGTHENS BEFORE THE INVERSION SETS UP. 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. SELY WNDS FRI-SUN AS AIR CIRCULATES ARND LRG HIPRES IN THE WRN ATLC. RDG CLOSE ENUF THAT SPDS SHUD BE AOB 10 KT. MAY HV A FEW STORMS. LTNG BIGGEST THREAT. && .CLIMATE... RECORD LOW OF 48 DEGREES SET EARLY THIS MORNING AT IAD...AND A RECORD LOW OF 55 WAS SET AT BWI. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...KCS NEAR TERM...KCS SHORT TERM...KCS LONG TERM...CEM AVIATION...KCS/CEM/WOODY! MARINE...KCS/CEM/WOODY! CLIMATE...KCS

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