Area Forecast Discussion
Issued by NWS Sterling, VA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
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 260707 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 307 AM EDT SAT JUL 26 2014 .SYNOPSIS...
-- Changed Discussion --
HIGH PRESSURE IS MOVING OFFSHORE. LOW PRESSURE IS EXPECTED TO TRACK ACROSS PENNSYLVANIA SUNDAY NIGHT WITH AN ASSOCIATED COLD FRONT MOVING INTO THE MID ATLANTIC. A REINFORCING FRONT WILL CROSS THE REGION MONDAY. HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT BRINGING COOLER AND DRIER CONDITIONS DURING MIDWEEK.
-- End Changed Discussion --
&& .NEAR TERM /TODAY/...
-- Changed Discussion --
AN UPPER-LEVEL DISTURBANCE WILL PASS THROUGH THE REGION THIS MORNING. A BKN TO OVC DECK OF MID-LEVEL CLOUDS IS EXPECTED WITH THIS DISTURBANCE. A SURFACE TROUGH WILL DEVELOP OVER THE REGION...MOST LIKELY EXTENDING FROM NORTH-CENTRAL MARYLAND SOUTH AND WEST INTO CENTRAL VIRGINIA. THERE IS A SMALL THETA-E GRADIENT AND PWAT GRADIENT ALONG THE BOUNDARY. A FEW SHOWERS CANNOT BE RULED OUT NEAR AND EAST OF THE BOUNDARY THIS MORNING...BUT MOST LOCATIONS WILL LIKELY END UP DRY SINCE MOST OF THE FORCING FROM THE UPPER-LEVEL DISTURBANCE IS EXPECTED TO REMAIN TO OUR NORTH. HIGH PRESSURE WILL CONTINUE TO MOVE OUT INTO THE ATLANTIC LATER TODAY. A SOUTHERLY FLOW WILL ALLOW FOR WARMER AND MORE HUMID CONDITIONS TO RETURN...AND THERE SHOULD BE AT LEAST SOME SUNSHINE BEHIND THE DEPARTING UPPER-LEVEL DISTURBANCE. MAX TEMPS WILL RANGE FROM THE 70S IN THE MOUNTAINS TO THE UPPER 80S/NEAR 90 IN THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS. THE HEAT AND HUMIDITY WILL LEAD TO AN UNSTABLE ATMOSPHERE THIS AFTERNOON...ESPECIALLY NEAR AND EAST OF THE SURFACE TROUGH ACROSS THE WASHINGTON AND BALTIMORE METROPOLITAN AREAS INTO SOUTHERN MARYLAND. A FEW SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP ACROSS THESE LOCATIONS. COVERAGE WILL BE ISOLATED TO WIDELY SCATTERED SINCE FORCING ALONG THE PRESSURE TROUGH WILL BE WEAK.
-- End Changed Discussion --
&& .SHORT TERM /TONIGHT/...
-- Changed Discussion --
A POTENT SHORTWAVE IN THE WESTERLY FLOW ALOFT WILL APPROACH THE AREA TONIGHT. MOST OF THE FORCING SHOULD REMAIN TO THE WEST...BUT THE SURFACE TROUGH WILL STRENGTHEN OVERHEAD AND EVEN RETROGRADE WESTWARD. THEREFORE...A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE TONIGHT...BUT COVERAGE ACROSS MOST AREAS SHOULD BE ISOLATED OR WIDELY SCATTERED SINCE MOST OF THE FORCING WILL REMAIN TO OUR WEST OVER THE OHIO VALLEY. MIN TEMPS WILL RANGE FROM THE 60S IN THE MOUNTAINS TO THE MIDDLE 70S IN DOWNTOWN WASHINGTON AND BALTIMORE... AND IT WILL FEEL NOTICEABLY MORE HUMID.
-- End Changed Discussion --
&& .LONG TERM /SUNDAY THROUGH FRIDAY/...
-- Changed Discussion --
THE PRIMARY ACTION DURG THE XTND PD LOOKS TO BE COMING AT THE BEGINNING. SYNOPTICALLY THIS SUMMER CERTAINLY HAS BEEN OUT OF THE NORM (IE..AN ABSENCE OF THE SUB TROP HIGH) AND IT LOOKS LK THIS WL HOLD TRUE FOR THE END OF JUL AS WELL. IT APPEARS THAT AN UNUSUALLY STRONG AREA OF LOW PRES WL BE TRACKING ACROSS PA SUN EVE. THIS WL PLACE THE MID ATLC SUN IN AN UNSTABLE AIR MASS W/ CAPES OVR 1000. SPC HAS ENTIRE CWA IN A SLT RISK. ONE THING THAT WOULD MAKE THIS THREAT STRONGER IS IF AREA GETS BRKS IN CLDS DURG MIDDAY TO ALLOW FOR HTG/INSTABILITY. HIGHS SEASONABLE... GNRLY IN U80S...PSBLY 90 IN THE CIITES. CHC FOR RA/TSTMS XPCTD TO CONT SUN NGT AHD OF A CD FNT. HOW MUCH INSTABILITY WL RMN POST-SUNSET WL HELP TO DETERMINE IF THERE WL BE A CONT SVR THREAT. LOWS RANGING FM THE M60S TO L70S. CURRENTLY IF LOOKS LK THE ACTUAL CD FNT WON`T PUSH E OF THE RGN UNTIL LATE MON...HENCE MORE POPS/CHCS FOR CNVCTN. HIGHS IN LM80S. AFTR THAT THE NEXT SVRL DAYS - THE LAST PART OF JUL...THE CONTINENTAL U.S. SHOULD BE UNDER A WRN RDG/ERN TROF. THIS WL KEEP TEMPS IN THE MID ATLC BLO NRML. AS I`VE WRITTEN IN SVRL DSCNS RECENTLY WE ARE AT THE CLIMATOLOGICALLY WARMEST TIME OF THE YR - HIGHS SHOULD GNRLY BE IN THE U80S/LOWS IN THE MU60S. AS OF NOW IT LOOKS LK HIGHS TUE-FRI SHOULD BE IN THE L80S. LOW TEMPS OUTSIDE OF WARMER CITIES WL BE A60...PSBLY EVEN INTO THE U50S. IT LOOKS LK IT SHOULD BE DRY TUE-FRI.
-- End Changed Discussion --
&& .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
-- Changed Discussion --
PATCHY BR IS POSSIBLE EARLY THIS MORNING ACROSS THE WESTERN TERMINALS. VFR CONDITIONS WILL PERSIST FOR THE REST OF TODAY. A FEW SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE EASTERN TERMINALS...ESPECIALLY THIS AFTERNOON. HOWEVER...COVERAGE WILL BE ISOLATED TO WIDELY SCATTERED. A FEW MORE SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE TERMINALS TONIGHT...BUT AGAIN COVERAGE WILL BE ISOLATED TO WIDELY SCATTERED SINCE MOST OF THE FORCING WILL BE TO OUR WEST OVER THE OHIO VALLEY. PATCHY BR MAY REDUCE VSBYS LATE TONIGHT. IN THE XTND...TSTMS ARE PSBL SUN..SUN NGT...AND MON. IT IS LKLY THAT L.T. VFR CONDS WL OCCUR IF STORMS DVLP OVR AN AIRPORT ALONG W/ THE PSBLTY OF STRONG WINDS. CONDS XPCTD TO BE VFR TUE AND WED.
-- End Changed Discussion --
&& .MARINE...
-- Changed Discussion --
A SOUTHERLY FLOW HAS DEVELOPED AROUND DEPARTING HIGH PRESSURE AND THE SOUTHERLY FLOW WILL CONTINUE THROUGH TONIGHT. THE PRESSURE GRADIENT WILL STRENGTHEN A BIT THIS AFTERNOON AND TONIGHT...CAUSING SOUTHERLY WINDS TO CHANNEL UP THE MARYLAND CHESAPEAKE BAY AND LOWER TIDAL POTOMAC RIVER. A SMALL CRAFT ADVISORY IS IN EFFECT FOR THE MARYLAND CHESAPEAKE BAY FROM SOUTH OF POOLES ISLAND TO SMITH POINT...AND THE LOWER TIDAL POTOMAC RIVER FROM COBB ISLAND TO SMITH POINT. WIND GUSTS MAY BE MARGINAL THIS AFTERNOON DUE TO THE RELATIVELY COOLER WATERS...BUT WILL CONTINUE WITH THE HEADLINE FOR NOW DUE TO THE STRENGTHENING GRADIENT. HIGHER CONFIDENCE WITH SCA WIND GUSTS IS FOR TONIGHT. TSTMS XPCTD ON THE WATERS...ESPECIALLY SUN AFTN/EVE. THESE MAY GENERATE STRONG GUSTY WINDS. AN SCA IS XPCTD MON AS A CD FNT MOVES THRU THE WATERS. THIS MAY CONT INTO MON NGT. TUE-THU LOOK MORE TRANQUIL.
-- End Changed Discussion --
&& .TIDES/COASTAL FLOODING...
-- Changed Discussion --
A LIGHT SOUTHERLY FLOW HAS CAUSED TIDAL ANOMALIES TO INCREASE TO AROUND ONE-HALF FOOT ABOVE NORMAL. THIS WILL CAUSE WATER LEVELS TO APPROACH MINOR FLOODING FOR SENSITIVE AREAS NEAR HIGH TIDE THIS MORNING FOR LOCATIONS ALONG THE WESTERN SHORE OF THE MARYLAND CHESAPEAKE BAY AND THE SHORE OF THE UPPER TIDAL POTOMAC RIVER. HOWEVER...WATER LEVELS SHOULD REMAIN JUST BELOW THESE THRESHOLDS SINCE THE FLOW WILL BE LIGHT. THE HIGH TIDE CYCLE THIS AFTERNOON AND EVENING WILL BE THE LOWER OF THE TWO...SO MINOR FLOODING IS NOT EXPECTED. HOWEVER...THE SOUTHERLY FLOW MAY STRENGTHEN A BIT TONIGHT AND THE HIGH TIDE CYCLE LATE TONIGHT INTO SUNDAY MORNING WILL BE THE HIGHER OF THE TWO. MINOR TIDAL FLOODING IS POSSIBLE FOR SENSITIVE AREAS NEAR HIGH TIDE LATE TONIGHT INTO SUNDAY MORNING.
-- End Changed Discussion --
&& .LWX WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 2 AM EDT SUNDAY FOR ANZ531>534-537-539>543.
-- End Changed Discussion --
&& $$ PRODUCTS...BJL/WOODY!

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