Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 230111 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 911 PM EDT TUE JUL 22 2014 .SYNOPSIS... HIGH PRESSURE WILL NEAR THE EASTERN SEABOARD TONIGHT. A COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY...AND MOVE THROUGH THE REGION WEDNESDAY NIGHT INTO EARLY THURSDAY. HIGH PRESSURE IS EXPECTED TO RETURN TO THE REGION TO END THE WORK WEEK. && .NEAR TERM /THROUGH WEDNESDAY/... HIGH PRESSURE CONTS IN THE WRN ATLC OFF THE MID ATLC/CAROLINA COAST. SHRA HV BEEN LMTD...RELEGATED MAINLY TO THE APLCN RDGS. WITH THE LOSS OF DAYTIME HEATING...THERE SHUDNT BE MUCH MORE TO THEIR LIFESPAN. FOR THAT MATTER...CLDS HV BEEN LESS XTNSV THAN LAST NGT. SINCE THERE/S LESS INFLUENCE FM THE SERN CONUS DISTURBANCE /DRY AIR AHD OF THE NXT CDFNT HAS BEEN SHUNTED SEWD OVER CWFA/...THINK THERE WL BE LESS CLDCVR. THAT POSES MORE FOG CONCERNS INSTEAD. GNLY GOING A MORE OPTIMISTIC RTE...AS PATCHY FOG HAS BEEN ADDED TO THE MTN/FOOTHILL VLYS...BUT AM KEEPING THE I-95 CRRDR FOG-FREE. WNDS HVNT DCPLD YET...AND THE LGT SLY FLOW/UPR 60S-LWR 70S DEWPTS NOT GREAT FOR RADL COOLING. MAY HV TO NUDGE MIN-T GRID UPWD DUE TO THOSE DEWPTS. WEDNESDAY STARTS WITH HIGH PRESSURE EXTENDING FROM THE OFFSHORE WATERS AND INTO THE CAROLINAS...WITH A COLD FRONT EXTENDING ACROSS THE LOWER GREAT LAKES AND OHIO VALLEY. THE COLD FRONT WILL APPROACH DURING THE DAY...WHILE A 500MB TROUGH STRENGTHENS OVER THE THE SAME REGION. COMBINATION OF INSTABILITY...LIFT AND MOISTURE IS EXPECTED TO SUPPORT SHOWERS AND THUNDERSTORMS...WITH ACTIVITY MORE LIKELY OVER NORTHERN AND WESTERN PORTIONS OF THE FORECAST AREA THAT WILL BE CLOSER TO THE APPROACHING FRONT. ISOLATED SEVERE STORMS WILL ALSO BE POSSIBLE ACROSS WESTERN MD AND THE EASTERN WV PANHANDLE...WHICH SHOULD BE IN THE RIGHT ENTRANCE REGION OF THE JET STREAM BY LATE IN THE DAY. DAMAGING WINDS IS LIKELY TO BE THE MAIN THREAT. WEDNESDAY WILL BE THE WARMEST DAY OF THE WEEK...WITH HIGHS IN THE LOW 90S AT MOST LOCATIONS. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... THE COLD FRONT IS EXPECTED TO MOVE THROUGH MOST OF THE FORECAST AREA WEDNESDAY NIGHT...AND SHOULD BE EAST OF THE I-95 CORRIDOR BY THURSDAY MORNING. SHOWER/TSTM ACTIVITY SHOULD SHIFT EWD ACCORDINGLY. SEVERE THREAT IS UNCERTAIN...AS BETTER DYNAMICS WILL BE OFFSET BY LOWER NIGHTTIME INSTABILITY. LOWS RANGE FROM THE MID 60S OVER EASTERN WV...BEHIND THE FRONT...TO THE MID 70S ALONG AND EAST OF I-95. COLD FRONT MOVES EAST OF THE REGION ON THURSDAY...WHILE AN UPPER TROUGH APPROACHES FROM THE WEST. SHOWER/TSTM CHANCES CONTINUE WITH COOLER AIR ALOFT...BUT WITH A N-NW FLOW CHANCE OF SEVERE WX IS UNLIKELY AT THIS TIME. TEMPS WILL BE COOLER WITH HIGHS RANGING FROM THE UPPER 70S OVER HIGHER ELEVATIONS TO THE MID 80S ELSEWHERE. UPPER TROUGH MOVES THROUGH THURSDAY NIGHT...WITH DRY CONDITIONS EXPECTED EXCEPT POSSIBLY OVER SRN MD AND PORTIONS OF THE PIEDMONT. LOWS DROP INTO THE 50S AND 60S. && .LONG TERM /FRIDAY THROUGH TUESDAY/... A RIDGE OF HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST FRIDAY AND FRIDAY NIGHT TO ALLOW COOLER AND DRIER AIR TO PUSH INTO THE REGION THROUGH SATURDAY. WITH THE HIGH MOVING TO THE COAST AND OFFSHORE DURING THE DAY SATURDAY...SOUTHEAST TO SOUTHERLY WINDS WILL EVOLVE...THUS PERHAPS SPAWNING A SHOWER IN THE POTOMAC HIGHLANDS WITH THE UPSLOPE COMPONENT. DISTURBANCES IN THE UPPER LEVELS WILL ROTATE IN FROM THE OHIO VALLEY AND LOWER GREAT LAKES SATURDAY NIGHT AND SUNDAY...THUS...BRINGING THE CHANCE FOR SHOWERS AND THUNDERSTORMS. AS FOR SUNDAY NIGHT THROUGH TUESDAY...A POTENT UPPER LEVEL STORM SYSTEM WILL LINGER ACROSS THE GREAT LAKES REGION. SEVERAL WAVES OF ENERGY WILL ROTATE AROUND IT AND ACROSS THE MID ATLANTIC REGION. THE CHANCE OF SHOWERS AND THUNDERSTORMS...ONCE AGAIN...WILL BECOME A NUISANCE TO THE REGION. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/... VFR MOST OF THE NIGHT...BUT MVFR VSBYS WITH FOG IS POSSIBLE LATE TONIGHT INTO THE EARLY MORNING HOURS WITH MOIST AIR OVER THE REGION. HV CONFINED THE VSBY RESTICTIONS TO CHO-MRB...AWAY FM THE HUBS. ITS NOT BYD THE REALM OF PSBLTY THAT MVFR VSBYS CUD OCCUR AT IAD TOO...OR THAT MRB-CHO MAY BRIEFLY DROP TO IFR. SCATTERED SHOWERS AND TSTMS POSSIBLE WED AFTN INTO EARLY THU. AN OFFSHORE HIGH WILL PUSH UP THE HEAT/HUMIDITY BEFORE TSTMS ARRIVE/DEVELOP...WHILE A COLD FRONT APPROACHES FROM THE NW. THE FRONT WILL LIKELY MOVE ACROSS THE AREA LATE WED INTO EARLY THU...SWEEPING THIS ACTIVITY OFF THE COAST BY LATE THU AFTN. VFR CONDITIONS WITH LIGHT AND VARIABLE WINDS EXPECTED FRIDAY THROUGH SATURDAY AT ALL TERMINALS. && .MARINE... SLY CHANNELING HAS COME UP THE CHSPK BAY...PLACING TPLM2 AT THE DOORSTEP OF SCA. WRF-ARW4 HAS BEEN STRONGER THAN THE REST...AND LTST RUNS HV BEEN STRONGER STILL...BUT EVEN IT SUGGESTING THAT THE PEAK OCCURRING ATTM...W/ WNDS BLO ANY CRIT LVL BY 02-03Z. THEREFORE...OPTED FOR MARINE WX STMT VS A TARGETED SCA. SLY WNDS ARND 10 KT FOR THE OVNGT HRS. LIGHT S-SW FLOW WILL CONTINUE WEDNESDAY AND MAXIMIZE JUST BEFORE THE PASSAGE OF A COLD FRONT EARLY THU. SHOWERS AND TSTMS POSSIBLE WED EVE INTO THE OVERNIGHT. NO MARINE HAZARDS EXPECTED FRIDAY THROUGH SATURDAY. && .TIDES/COASTAL FLOODING... TIDAL ANOMALIES DROPPED TO AROUND A HALF-FOOT EARLIER TODAY...AND REMAIN THERE ATTM. THOSE DEPARTURES...IF STEADY...WOULD POSE NO CONCERN DURING HIGH TIDE TONIGHT...EVEN AT SENSITIVE LOCATIONS. HOWEVER...AM NOT CERTAIN WHETHER DEPARTURES WONT BE INCREASING AGAIN WITH THE INCOMING TIDE CONSIDERING THE 15 KT SLY FLOW THAT HAS DVLPD ON THE BAY THIS EVNG. BASED ON LOW CONFIDENCE AND LOW IMPACT /IT WOULD BE A THRESHOLD EEVNT AT ANNAPOLIS/...HAVE OPTED TO NOT ISSUE AN ADVY AT THIS TIME. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE. && $$ SYNOPSIS...KCS NEAR TERM...HTS/KCS SHORT TERM...KCS LONG TERM...KLW AVIATION...HTS/KCS/KLW MARINE...HTS/KCS/KLW TIDES/COASTAL FLOODING...HTS

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