Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 250813 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 413 AM EDT MON AUG 25 2014 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE REGION THROUGH WEDNESDAY BEFORE A COLD FRONT PASSES THROUGH THE AREA WEDNESDAY NIGHT INTO EARLY THURSDAY. HIGH PRESSURE WILL RETURN FOR LATE IN THE WEEK. && .NEAR TERM /THROUGH TUESDAY/...
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UPDATE...DENSE FOG ADVISORY IN EFFECT FOR THE INTERSTATE 81 CORRIDOR INCLUDING THE NORTHERN SHENANDOAH VALLEY. HIGH PRESSURE WILL RESIDE ACROSS THE MID ATLANTIC TODAY. WINDS HAVE BECOME CALM IN MANY LOCATIONS. RADIATIONAL COOLING HAS LED TO PATCHY FOG DEVELOPMENT ACROSS THE REGION AND MORE WIDESPREAD FOG IN VALLEY LOCATIONS. FOG MAY BECOME LOCALLY DENSE AT TIMES NEAR AND IN VALLEYS EARLY THIS MORNING LEADING TO POOR VISIBILITY. SUNNY CONDITIONS ARE EXPECTED TODAY WITH FCST MAX TEMPS REACH THE LOW 80S. ONSHORE EASTERLY WINDS AROUND 5-10MPH EXPECTED TODAY. HIGH PRESSURE CONTINUES ACROSS THE REGION TONIGHT AND TUESDAY AND CLEAR SKIES AND CALM WINDS WILL LEAD TO ANOTHER NIGHT AND EARLY MORNING OF FOG DEVELOPMENT. FCST MIN TEMPS WILL REACH THE 50S AND LOW 60S IN THE CITY CENTERS. MOSTLY SUNNY CONDITIONS EXPECTED TUESDAY WITH MAX TEMPS AROUND 80 IN THE CENTRAL FOOTHILLS AND IN THE MID 80S ELSEWHERE. ONSHORE EASTERLY FLOW CONTINUES TUESDAY.
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&& .SHORT TERM /TUESDAY NIGHT THROUGH WEDNESDAY NIGHT/... UPPER RIDGE FLATTENS OUT TUESDAY NIGHT INTO WEDNESDAY. THIS WILL ALLOW A COLD FRONT TO APPROACH LATE WEDNESDAY INTO WEDNESDAY NIGHT. WEDNESDAY SHOULD BE A WARM DAY AHEAD OF THE FRONT. THERE IS THE CHANCE FOR A FEW SHOWERS AND THUNDERSTORMS TO DEVELOP LATER IN THE AFTERNOON INTO THE EVENING ACROSS THE NORTHWEST PORTION OF THE CWA. BUT WITH LOSS OF DAYTIME HEATING...MUCH OF THE CONVECTION SHOULD DISSIPATE OVERNIGHT EVEN THOUGH THE BOUNDARY WILL RESIDE ACROSS THE CWA. && .LONG TERM /THURSDAY THROUGH SUNDAY/... FRONT SETTLES SOUTH OF THE CWA TO END THE WEEK...AS OFFICIAL NHC FORECAST SHOWS CRISTOBAL REMAINING WELL OFF THE COAST AND ACCELERATING FURTHER OUT TO SEA. EVEN BEHIND THE FRONT THURSDAY SHOULD BE ANOTHER WARM/ABOVE AVERAGE DAY WITH ONLY ISOLATED DIURNAL CONVECTION NEAR THE POTOMAC HIGHLANDS. SURFACE HIGH TO THE NORTH ON THURSDAY SHIFTS OFFSHORE FRIDAY...PROMOTING A CHANGE TO EASTERLY FLOW FOR FRIDAY. THIS MAY TEMPER HEATING A LITTLE...RESULTING IN NEAR NORMAL TEMPS. UPPER RIDGE BUMPS BACK NORTHWARD ON SATURDAY. BUT WITH MOIST/WARM ADVECTION A FEW AFTERNOON/EVENING SHOWERS/THUNDERSTORMS WILL BE POSSIBLE ESPECIALLY NEAR THE HIGHER TERRAIN. CONTINUE CHANCE POPS ON SUNDAY WITH A SURFACE TROUGH IN PLACE. && .AVIATION /08Z MONDAY THROUGH FRIDAY/... PATCHY FOG WILL CONTINUE TO DEVELOP THIS MORNING. OBS HAVE TAKEN CHO-MRB IN AND OUT OF IFR VSBYS OVERNIGHT BUT IFR/LIFR SHOULD LOCK IN SOON. MVFR/IFR VSBY POSSIBLE AT IAD EARLY THIS MORNING. DRY CONDITIONS EXPECTED TODAY. PATCHY FOG IS EXPECTED AT CHO-IAD-MRB EARLY TUESDAY MORNING. MVFR/IFR CONDITIONS ARE POSSIBLE. COLD FRONT IS FORECAST TO MOVE THROUGH WEDNESDAY NIGHT INTO EARLY THURSDAY. LOW PROBABILITY OF TSRA WITH THE FRONT GIVEN UNFAVORABLE TIME OF DAY DURING PASSAGE. HIGH PRESSURE BUILDS TO END THE WEEK. && .MARINE... EASTERLY FLOW ACROSS THE WATERS WILL CONTINUE THROUGH TUESDAY. WINDS SHOULD STAY 10-15 KTS AND BELOW WITH THE EXCEPTION OF THE LOWER TIDAL POTOMAC AND MD BAY SOUTH OF DRUM PT. A GRADIENT BETWEEN THE APPROACHING SFC HIGH AND TS CRISTOBAL WILL LEAD TO E WINDS WITH GUSTS UP TO 20 KTS. SCA IS IN EFFECT THIS MORNING. COLD FRONT WILL MOVE THROUGH BY EARLY THURSDAY. WIND SHIFT TO NORTH OCCURS BEHIND THE FRONT BUT IS EXPECTED TO REMAIN BELOW SCA THRESHOLDS ATTM. && .TIDES/COASTAL FLOODING... EASTERLY FLOW OVER THE WATERS WILL CONTINUE THROUGH TUESDAY AND WATER LEVELS WILL STAY ELEVATED ON THE UPPER TIDAL POTOMAC AND WESTERN SHORE OF THE CHESAPEAKE BAY. ANOMALIES HAVE DROPPED SLIGHTLY AND ARE AROUND AN INCH DUE TO WINDS BECOMING LIGHTER. THE HIGH TIDE THIS MORNING WILL BE THE HIGHER OF THE TWO HIGH TIDES. WATER IS CRESTING ACROSS SOUTHERN MD EARLY THIS MORNING AND WATER LEVELS SEEM TO BE FALLING JUST SHORT OF MINOR COASTAL FLOODING. EASTERLY WINDS WILL INCREASE AFTER SUNRISE AND LEVELS ARE EXPECTED TO REACH MINOR THRESHOLDS AT SENSITIVE LOCATIONS SUCH AS ANNAPOLIS. AT THIS TIME WILL LEAVE BALTIMORE OUT OF COASTAL FLOODING ADVISORY AS ANOMOLIES HAVE DROPPED. WATER LEVELS AT THE SW WATERFRONT/DC WILL BE CLOSE TO MINOR FLOODING THIS MORNING. ONSHORE FLOW CONTINUES THROUGH TUESDAY AND MINOR COASTAL FLOODING WILL BE POSSIBLE TONIGHT MAINLY FOR SW WATERFRONT/DC. IT WILL BE THE LOWER OF THE HIGH TIDES FOR THE MD CHESAPEAKE BAY AND THEREFORE NO FLOODING IS EXPECTED. && .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...COASTAL FLOOD ADVISORY UNTIL 11 AM EDT THIS MORNING FOR DCZ001. MD...COASTAL FLOOD ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR MDZ017-018. COASTAL FLOOD ADVISORY UNTIL 11 AM EDT THIS MORNING FOR MDZ014. VA...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR VAZ025>031. COASTAL FLOOD ADVISORY UNTIL 11 AM EDT THIS MORNING FOR VAZ054. WV...DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR WVZ050>053- 055. MARINE...SMALL CRAFT ADVISORY UNTIL NOON EDT TODAY FOR ANZ534-537-543.
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&& $$ SYNOPSIS...BPP/HAS NEAR TERM...HAS SHORT TERM...BPP LONG TERM...BPP AVIATION...BPP/HAS MARINE...BPP/HAS TIDES/COASTAL FLOODING...

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