Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 290841 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 441 AM EDT FRI MAY 29 2015 .SYNOPSIS... HIGH PRESSURE OVER LAKE ONTARIO WILL SHIFT SOUTHEAST AND REINFORCE HIGH PRESSURE OFFSHORE TODAY. SOUTHERLY WINDS WILL CONTINUE TO BRING WARM AND HUMID CONDITIONS TO THE MID- ATLANTIC THROUGH SATURDAY. A COLD FRONT WILL ARRIVE SUNDAY AND STALL OVER THE AREA THROUGH MONDAY. && .NEAR TERM /THROUGH TONIGHT/... 06Z SFC ANALYSIS INDICATING FRONTAL BOUNDARY REMAINS STRETCHED ACROSS THE NORTHERN PORTION OF THE CWA...NEAR THE MASON DIXON LINE. THIS BOUNDARY CONTINUES TO BE A TRIGGER POINT FOR ISO ACTIVITY...MAINLY EAST OF THE BLUE RIDGE. MESO MODELS HINTING THAT THESE SHOWERS AND TSTMS SHOULD DIMINISH BY DAYBREAK AND AS SUCH WILL CARRY ISO POPS THRU 12Z. WITH SKIES SCATTERING OUT OVER MUCH OF THE AREA...COMBINING WITH DECENT LOW LVL MOISTURE...EXPECTING AT LEAST PATCHY FOG DEVELOPMENT THRU DAYBREAK AS WELL. FOR TODAY...YET ANOTHER DAY OF HOT...HUMID AND SCT SHOWERS AND TSTMS. NEAR STATIONARY FRONT WEAKENS BY THIS AFTN...WITH HIGH PRESSURE BUILDING IN AT THE SFC AND UPPER LVL RIDGING PERSISTING. ISO SHOWERS AND MAYBE AN ISO TSTM PSBL ALONG THIS BOUNDARY MIDDAY AS SBCAPE REACHES 500-100 J/KG. HOWEVER...WITH LACK OF FORCING ALOFT...AND THE LOSS OF THE FRONT BY THIS AFTN...EXPECTING THE ACTIVITY TO TRANSITION MORE ALONG AND WEST OF THE BLUE RIDGE...OCCURRING WITH THE COMBO OF DECENT INSTABILITY AND TERRAIN CIRCULATIONS OFF THE SELY FLOW. WEAK SHEAR SHOULD MINIMIZE ANY THREAT OF STRONGER STORMS. HAVE ONLY SLIGHT CHC POPS IN FOR THE WESTERN AREAS TONIGHT WITH DCRSNG INSTABILITY...THOUGH A PASSING WEAK SHORTWAVE COULD TRIGGER AN ISO SHOWER. AS HAS BEEN THE STORY ALL WEEK...TEMPS WELL ABV NORMAL. MUCH OF THE AREA WILL SEE 80S TODAY...WITH ISO SPOTS POSSIBLY REACHING 90 IN THE PIEDMONT. MILD NIGHT TONIGHT WITH LOWS IN THE 60S. && .SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... ANOTHER DAY OF WARM CONDITIONS SATURDAY AS THE REGION REMAINS POSITIONED BETWEEN HIGH PRESSURE OFFSHORE AND A COLD FRONT SLOWLY APPROACHING FROM THE WEST. WILL BEGIN TO SEE HEIGHT FALLS DURING THE DAY SAT AS UPPER LVL RIDGE MOVES EAST AHEAD OF AN APPROACHING UPPER LVL TROUGH. WHILE INSTABILITY VALUES NOT AS STRONG AS DURING THE WORK WEEK...STILL EXPECTING ENOUGH OF AN UNSTABLE AIRMASS FOR TSTM DEVELOPMENT MAINLY WEST OF THE BLUE RIDGE AND UP ALONG THE MASON- DIXON LINE...ESP MIDDAY WITH A WEAK SHORTWAVE PASSING ALONG THE PA/VA BORDER. HAVE CAPPED AT HIGH END CHC (SCT) POPS FOR NOW. PRE FRONTAL SFC TROUGH WILL KEEP THE CHC FOR PCPN ONGOING SAT EVENING...WITH THE FRONT THEN NEARING THE WESTERN AREAS BY SAT MORNING. WILL MAINTAIN POPS OVERNIGHT...THOUGH THINKING ONLY A SLIGHT CHC OF OCCURRING. && .LONG TERM /SUNDAY THROUGH THURSDAY/... CDFNT WL MV THRU DURING THE DAY SUN. ALTHO INSTBY WL BE RESPECTABLE...ITS ALSO NOT EXTREME. BAROCLINICITY...DROPPING HGTS AND DAYTIME HEATING WL ALL ASSIST IN TSRA DVLPMNT. ENVIRONMENT MAY SUPPORT A FEW STRONGER STORMS. WUD THINK THAT WIND MAY BE THE BIGGER THREAT...ALTHO MATURE STORMS CUD DROP A LTL HAIL TOO. AND...HAS BEEN THE CASE FOR SVRL DAYS NOW...HIGH PWATS WL YIELD HVY RAINERS. GDNC COMING INTO CONSENSUS THAT SFC FNT WL MAKE IT THRU...WHICH WL ALLOW A COOLER AMS TO INFILTRATE THE RGN. HWVR...H8 WAA WL BE DVLPG ALMOST RIGHT AWAY. SINCE AREA WL BE W/IN FRNTL ZONE...AN OVERRUNNING PTTN WL SET UP...WHICH SPELLS A PD OF WET WX MON-MON NGT...AND PERHAPS INTO TUE. CLD GRIDS STAY RATHER...WHICH ADDS CONFIDENCE IN KEEPING MAXT IN THE 60S. CNDN HIPRES WL EVENTUALLY WIN OUT BY MIDWEEK. TEMPS WL MODERATE WED- THU AS PCPN CHCS DECREASE AND CLDS THIN. CONUS UPA PTTN WL STILL BE QUIT AMPLIFIED...WHICH DOES SUPPORT CLDS SPILLING INTO AREA...AND PERHAPS EVEN A FEW SHRA ON THE PERIPHERY OF RDG /SRN-WRN CNTYS/. && .AVIATION /09Z FRIDAY THROUGH TUESDAY/... GENERALLY VFR CONDITIONS THRU THE TAF PERIOD. PSBL FOG DEVELOPMENT THIS MORNING KIAD/KCHO/KMRB SO WILL KEEP VIS 3-5SM IN. ANY FOG WILL DISSIPATE BY 13Z. SCT SHOWERS AND TSTMS THIS AFTN...WITH HIGHER CONFIDENCE OF OCCURRING KCHO/KMRB. WILL INCLUDE AS PREVAILING GROUP...WITH VCTS MENTION AT KIAD. LOW CONFIDENCE OF HAPPENING AT THE EASTERN THREE SITES...SO WILL HOLD OFF FOR NOW UNTIL CONFIDENCE INCREASES. LIGHT AND VRB WINDS WILL INCREASE AROUND 5 KTS FROM THE EAST BY 12Z...THEN BACK TO THE SE TO 10 KTS DURING THE DAY TODAY. SLY FLOW SETS UP TONIGHT THRU SAT NIGHT. INCRSG WINDS ON SAT WITH PSBL GUSTS UP TO 20 KTS DURING THE DAY. ANOTHER ROUND OF SHOWERS AND TSTMS PSBL AT MAINLY KMRB...WITH VERY LOW CONFIDENCE OF REACHING ANY OTHER SITES SAT-SAT NIGHT. TSRA SHUD BE NMRS SUN AS CDFNT DROPS THRU. WHILE XPCT PDS OF VFR...PDS OF FLGT RESTRICTIONS LKLY...W/ LCL AOB IFR PSBL W/IN STORMS. THIS WL CONT INTO SUN EVE. FLOW WL TURN NLY MON...BUT UNSETTLED CONDS XPCTD MON-MON NGT. SINCE FLOW WL BE ONSHORE /ENELY/ IN A MUCH COOLER AMS...WUD BE WARY OF LWR CLDS AND PDS OF FOG IN ADDITION TO SHRA...OR MAYBE EVEN DZ. GRDL IMPRVMNT XPCT TUE. && .MARINE... SUB-SCA CONDITIONS ON ALL THE WATERS THRU THIS MORNING. PSBL SLY CHANNELING COULD RESULT IN GUSTS REACHING 18 KTS THIS AFTN ON THE CHESAPEAKE BAY. CONFIDENCE TOO LOW TO ISSUE SCA AT THIS TIME. WILL BE ISSUING SCA FOR SAT FOR THE CHESAPEAKE BAY WITH GUSTS UP TO 20 KTS PSBL ON THE SLY FLOW. THE SCA CONDITIONS WILL CONTINUE THRU SAT NIGHT. CFP SUNDAY. STRONG STORMS MAY BE DVLPG ALONG/AHD OF FNT...WHICH WUD POSE A WIND THREAT. WUD ANTICIPATE SMW/S. ONCE FNT MAKES IT THRU... WINDS INCR IN NELY FLOW...WHICH WUD BE ON SUN NGT. SCA PSBL AT THAT TIME. NELY/ENELY FLOW WL CONT INTO TUE...BUT AT SPDS BLO CRITICAL THRESHOLDS. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM NOON SATURDAY TO 1 AM EDT SUNDAY FOR ANZ530-538>542. SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO 8 AM EDT SUNDAY FOR ANZ532>534-543. SMALL CRAFT ADVISORY FROM 10 AM SATURDAY TO 6 AM EDT SUNDAY FOR ANZ531. SMALL CRAFT ADVISORY FROM NOON SATURDAY TO 2 AM EDT SUNDAY FOR ANZ537. && $$ SYNOPSIS...HTS NEAR TERM...SEARS SHORT TERM...SEARS LONG TERM...HTS AVIATION...SEARS/HTS MARINE...SEARS/HTS

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