Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 210028 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 828 PM EDT WED MAY 20 2015 .SYNOPSIS... LOW PRESSURE PASSES TO THE SOUTH THURSDAY WITH HIGH PRESSURE BUILDING IN FOR THE WEEKEND. && .NEAR TERM /THROUGH THURSDAY/... MOCLR SKIES ATTM AS HIPRES STILL INFLUENCING WX. ONLY CLDS FM STREAKING CI. GDNC SUGGESTING THAT CLDS SHUD THICKEN TNGT... MAINLY OVNGT. NEAREST CLDS IN WRN WVA ATTM...SO THERES STILL SVRL HRS TO GO. GOING TEMP FCST IN GOOD SHAPE. DEWPTS STILL IN THE 40S...WHICH WL DELAY ANY LWR CLD DVLPMNT. LOW PRESSURE ALONG A STATIONARY FRONT STRETCHING FROM TN TO THE CAROLINAS WILL GET BETTER ORGANIZED TONIGHT AND MOVE EAST AND OFF OF THE CAROLINAS BY THU EVENING. LIGHT RAIN WILL DEVELOP NORTH OF THE LOW PRES CENTER AND ALONG AN INVERTED SFC TROF AND OVERSPREAD THE REGION LATE TONIGHT AND CONTINUE THRU THU MORNING BEFORE IT BEGINS TO TAPER OFF IN THE AFTERNOON. LTST MESOSCALE GDNC AND 18Z GFS/NAM RUNS SUGGEST PCPN WL BE SPREADING IN PRE-DAWN...W/ A QUARTER TO HALF INCH QPF PSBL DURING THE DAY. GIVEN THAT DATA THINK THERE IS SUFFICIENT EVIDENCE TO BUMP POPS UP TO CAT ALL CNTYS XCPT FOR LKLY ACRS NRN MD. THE DRY LLVL CONDS SUGGEST THAT MOST OF THE NGT WL REMAIN DRY. ADDED A LTL BETTER TIME DEFINITION INTO DATABASE. NO OTR CHGS ATTM. && .SHORT TERM /THURSDAY NIGHT THROUGH FRIDAY NIGHT/... SFC LOW NEAR THE CAROLINA COAST BY 00Z FRIDAY...PUSHING OFFSHORE OVERNIGHT THURS. UPPER LVL FORCING THAT HAD AIDED IN PCPN DEVELOPMENT DURING THE DAY THURS WILL PUSH EAST AS WELL...ALLOWING PCPN TO TAPER OFF FROM WEST TO EAST BY THE SECOND HALF OF THE NIGHT. OVERNIGHT LOWS GENERALLY IN THE 40S AS CLEARING IS EXPECTED WITH DRIER AIR FILTERING IN. MAINLY DRY WX FRIDAY. UPPER LVL TROUGH SWINGS A COLD FRONT THRU MIDDAY...BUT WITH MOISTURE LACKING...NOT ANTICIPATING MUCH PCPN TO ACCOMPANY THE FRONT. KEPT JUST SLIGHT CHC OVER NW PORTIONS FOR TERRAIN CIRCULATION DEVELOPMENT WITH DIURNAL HEATING. ANY PCPN ENDS BY EVENING. SFC HIGH PRESSURE AND RIDGING ALOFT WILL LEAD TO DRY CONDITIONS HEADING INTO THE WEEKEND. HIGHS ON FRI NEAR SEASONAL WITH CAA BEHIND THE COLD FRONT DROPPING TEMPS FURTHER INTO THE 40S FOR FRI NIGHT. PATCHY FROST MAY BE PSBL IN EXTREME WESTERN POTOMAC HIGHLANDS WITH TEMPS DROPPING INTO THE 30S...THOUGH MOISTURE MIGHT BE TOO LACKING FOR FORMATION. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... PLEASANT WEATHER CONDITIONS ARE EXPECTED FOR SAT AND SUN WITH HIGH TEMPS IN THE 70S TO LOW 80S AS HIGH PRES MOVES OVER THE MID- ATLANTIC ON SAT AND THEN OFFSHORE SUN MORNING. A WARM FRONT LIFTS NORTH ON SUN NIGHT INTO MON BRINGING A SLIGHT CHANCE OF SHOWERS AND TSTMS. UPPER RIDGE AND BERMUDA HIGH SETTLE OVER THE REGION WITH HOT AND HUMID CONDITIONS FOR THE REGION...SO HAVE KEPT CHANCES FOR SHOWERS AND TSTMS FOR TUES... HIGH TEMPS COULD REACH THE 90S. SURFACE TROUGH KEEPS INSTABILITY OVER THE CWA FOR WED. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... VFR REST OF TNGT. LIGHT RAIN WILL OVERSPREAD AREA TERMINALS DURING THE MRNG PUSH AND CONTINUE THROUGH MID AFTN. MAY SQUEEZE IN MRNG PUSH BEFORE FLGT CONDS DROP TO MVFR. TOOK A SLGTLY MORE OPTIMISTIC RTE IN TAFS. IF A WORSE CASE SCENARIO OCCURRED... REDUCED CIGS/VSBYS MAY OCCUR ERLR THAN FCST. MVFR CIGS THRU THE AFTN AND INTO THURS EVENING WITH LINGERING PCPN...BCMG VFR BY THE LATTER HALF OF THE NIGHT. VFR CONDITIONS THEN FRI-FRI NIGHT WITH NW GUSTS UP TO 20 KTS PSBL FRI AFTN. VFR CONDITIONS EXPECTED FOR SAT AND SUN. && .MARINE... NLY/NWLY WINDS 10-15 KT THIS EVNG DIMINISHING TO 10 KT OR LESS BY ELY THU. ENELY WINDS THRU THE DAY ON THU AS LOPRES PASSES S OF THE WATERS...SPREADING RAIN ACRS THE AREA. WINDS WL PICKUP AGN THU NGT AS THE LOW PASSES OFFSHORE AND DEEPENS. WHILE MIXING WONT BE STELLAR...THERE SHUD BE ENUF WIND NEAR THE WATERS EDGE TO JUSTIFY SCA FOR MOST OF THE MD BAY/ERN INLETS. HV RAISED THE ADVY FOR JUST THOSE AREAS FOR THE ELY MRNG HRS FRI. BASED ON LATER DATA...AN EXPANSION INTO THE PTMC/WRN-NRN INLETS MAY BE REQD. ADVY MAY NEED TO BE XTNDD INTO THE DAYTIME FRI DUE TO PSBL GUSTS TO 20 KTS. INCRSG NW WINDS BEHIND COLD FRONT DURING THE DAY SHOULD RESULT IN SCA GUSTS. HIGH PRESSURE BUILDING IN FRI NIGHT WILL DIMINISH WINDS BACK TO SUB-SCA CONDITIONS. SUB-SCA CONDITIONS EXPECTED FOR SAT AND SUN. && .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 3 AM TO 8 AM EDT FRIDAY FOR ANZ531>534-540-541-543. && $$ SYNOPSIS...LFR NEAR TERM...HTS/LFR SHORT TERM...SEARS LONG TERM...IMR AVIATION...HTS/LFR/SEARS/IMR MARINE...HTS/SEARS/IMR

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