Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 061428 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 1028 AM EDT SUN JUL 6 2014 .SYNOPSIS... HIGH PRESSURE WILL GRADUALLY SHIFT EAST OFF THE SOUTHERN MID- ATLANTIC COAST TODAY...AND PERSIST THROUGH EARLY IN THE WEEK. A COLD FRONT WILL APPROACH THE REGION MID WEEK AND BECOME STATIONARY ACROSS SOUTHERN VIRGINIA. THIS FRONT WILL GRADUALLY DISSIPATE TOWARD THE END OF THE WEEK. && .NEAR TERM /THROUGH MONDAY/... HIGH PRES HAS MIGRATED TO A POSN OFF THE SC CST...ALLOWING FOR WINDS TO CHG FM THE COOL NRLY FLOW WE HAD YDA TO SWRLY TDA. THE 12Z IAD SNDG SHOWED THE ATMOSPHERE IS STILL QUITE DRY...BUT THIS WL BE CHANGING AS MORE MOISTURE GETS PUMPED INTO THE MID ATLC. TEMPS LOOK ON TRACK TO REACH THE MU80S THIS AFTN. THIS MRNG WAS ANOTHER COOL MRNG - ALTHO NOT QUITE AS COLD AS SAT MRNG A LOW OF 40 WAS RECORDED AT MILL GAP IN HIGHLAND CO. TNGT`S LOWS WL BE A FAIR BIT WARMER - IN THE 50S AT HIGHER ELEVS TO L70S IN THE CITIES. MOST OF AREA WL DROP INTO THE 60S. HGTS GRDLY LWR MON AS DEWPTS CREEP UPWD DUE TO SW WNDS...AND WL HV MODEST INSTBY BY THE END OF THE DAY. ASIDE FM LEE TROFFING...DONT SEE A CATALYST FOR TSRA ORGANIZED DVLPMNT. INSTEAD...WUD XPCT OROGRAPHICALLY DRIVEN DIURNAL TSRA...WHICH ARE MOST PRONE TO THE APLCNS. HV CONFINED POPS THERE FOR THE DAYTIME HRS. USED A HEALTHY DOSE OF MAV FOR MAXT. && .SHORT TERM /MONDAY NIGHT THROUGH TUESDAY NIGHT/... MON NGT...POTENTIAL FOR ANY DIURNAL CONVECTION TO CONTINUE INTO THE EARLY EVENING HOURS...BUT SREF ENSEMBLE OF INSTABILITY LIMITED TO UNDER 1000 J/KG FOR SFC-BASED CAPES. ANY SVR MON EVENING WOULD BE ISOLATED AS BEST VERTICAL SHEAR REMAINS NORTH OF THE AREA. TUE...ANOTHER HOT DAY WITH INCREASING HUMIDITY LEVELS EXPECTED AND BETTER CHANCES OF DIURNAL CONVECTION IN THE MOUNTAINS AND ALONG NORTHERN TIER OF COUNTIES. UPPER LEVEL DYNAMICS ARE WEAK SO NOT EXPECTING ANYTHING ORGANIZED WITH CONVECTION THAT DOES FIRE ALTHOUGH THERE COULD BE ISOLATED SVR MAINLY W OF THE BLUE RIDGE. FORECAST MODEL SOUNDINGS SUGGEST INCREASED INSTABILITY ON TUE VS MON. TUE NGT...ANY DIURNALLY DRIVEN CONVECTION WILL WIND DOWN QUICKLY AND EXPECT A PARTLY CLOUDY WARM AND HUMID OVERNIGHT. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... THE EXTENDED WILL BE DOMINATED BY THE SEMI STATIONARY BERMUDA HIGH PRESSURE RIDGE STRETCHED E-W ACROSS THE WESTERN ATLANTIC REGION THAT WILL HELP KEEP A WARM AND HUMID AIR MASS OVER THE REGION WED AND THU. THE OTHER FACTOR WILL BE A SERIES OF WEAK COLD FRONTS THAT WILL DROP DOWN FROM THE GREAT LAKES REGION LATE IN THE WEEK. THE FIRST FRONT WILL APPROACH ON WED. PRIOR TO THIS FRONT...A LEE TROUGH WILL SET UP...WHICH WILL HELP FOCUS LOW LEVEL CONVERGENCE. EXPECT POTENTIAL FOR SEVERE TSTMS WED AFTN ACROSS THE REGION... WITH HIGHEST ODDS PER LATEST SPC DAY 3 OTLK ACROSS THE POTOMAC HIGHLANDS. THU AND FRI...THE COLD FRONT STRUGGLES TO CROSS THE AREA ON THUR...BUT 1020 HIGH ON FRI COULD PUSH IT THOUGH THE REGION BY FRI AFTERNOON. ASSUMING THIS SCENARIO...THE FRONT WILL STALL OUT SOMEWHERE JUST SOUTH OF THE REGION LATE FRI...AND GRADUALLY DISSIPATE ON SAT. STILL TOO MUCH UNCERTAINTY WITH THE OVERALL SOLN FOR LATE IN THE WEEK...BUT EXPECT TEMPS TO BE A TAD COOLER THU AND FRI TO MORE SEASONABLE LEVELS...FROM EARLIER HEAT TUE-WED. && .AVIATION /14Z SUNDAY THROUGH THURSDAY/... VFR FOR VALID TAF PD. LONG TERM OUTLOOK...VFR CONDITIONS EXPECTED MON AND TUE WITH MVFR VSBYS AT IAD/MRB/CHO/MTN TUE MORNING IN FOG...AND TUE AFTN CIGS 045-060 WITH ISLD TSTMS. WED...SOME MVFR VSBYS POSSIBLE DUE TO EARLY MORNING HAZE/FOG...THEN AN APPROACHING COLD FRONT COULD PRODUCE MVFR CIGS/VSBYS IN SCTD SHOWERS/TSTMS DURING THE AFTN/EVENING WITH LOCAL IFR CIGS/VSBYS IN STRONGER TSTMS. WEAK COLD FRONTAL LINGERS ACROSS MID-ATLANTIC REGION THU. && .MARINE... SW WNDS ARND 10 KT ATTM. THAT SHUD INCR THIS AFTN AS A SFC RDG MVS OFFSHORE. MEAN LYR MIXING SUGGESTS 20 KT ON THE BAY/MOUTH OF THE PTMC. SCA ALREADY IN EFFECT 20Z...CONTG THRU TNGT WNDS WL BE ENHANCED BY A S/WV. MAY HV A SHORT LULL MON MRNG BEFORE DIURNAL MIXING...GRADIENT FLOW AND WAA YIELD EVEN GUSTIER WNDS. HV RAISED SCA FOR ALL WATERS BGNG 18Z MON. FOR MON NIGHT...EXPECT WIND GUSTS NEAR SCA LEVELS MON NIGHT ACROSS THE LOWER BAY...BUT SHOULD DIMINISH SOME TOWARD TUE MORNING. SOUTH TO SOUTHWESTERLY LOW LEVEL WINDS THROUGH MID WEEK ACROSS THE WATERS...AT TIMES SOUTHERLY CHANNELING WILL CREATE WIND GUSTS APPROACHING SCA LEVELS OVER THE MID TO LOWER BAY AND LOWER TIDAL POTOMAC TUE AND WED. AFTERNOON AND EVENING TSTM CHANCES TUE THROUGH THU ASSOCIATED WITH APPROACHING COLD FRONT TUE...AND FRONTAL BOUNDARY IN THE AREA WED AND THU. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 6 AM EDT MONDAY FOR ANZ530>534-537-539>541-543. SMALL CRAFT ADVISORY FROM 2 PM TO 9 PM EDT MONDAY FOR ANZ530>532-535>542. SMALL CRAFT ADVISORY FROM 2 PM MONDAY TO 6 AM EDT TUESDAY FOR ANZ533-534-543. && $$ UPDATE...WOODY! PRVS...HTS/SMZ

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