Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 200054 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 854 PM EDT TUE MAY 19 2015 .SYNOPSIS... A COLD FRONT WILL MOVE INTO THE ATLANTIC THIS EVENING. BEHIND THE FRONT A COOLER AND DRIER AIR MASS WILL ENTER THE AREA. LOW PRESSURE PASSES TO THE SOUTH THURSDAY WITH HIGH PRESSURE BUILDING IN FOR THE WEEKEND. && .NEAR TERM /THROUGH WEDNESDAY NIGHT/...
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A COLD FRONT IS LOCATED NEAR THE I-95 CORRIDOR THIS EVENING. A DEWPT GRADIENT EXISTS ACROSS THE REGION WITH 50S WEST OF THE I-95 CORRIDOR AND UPPER 60S/LOW 70S IN SOUTHERN MD. DRIER AIR WILL CONTINUE TO MOVE INTO THE REGION TONIGHT. A PRESSURE GRADIENT BEHIND THE FRONT WILL KEEP NW WINDS 5-10 MPH OVERNIGHT. PREVIOUS DISCUSSION... HIPRES WL BUILD FM THE UPR MIDWEST TNGT-TMRW. DRY WX THRU THE PD. AM SCATTERING CLDS OUT ELY IN THE EVNG...W/ FEW-SCT CLDS THRU WED AFTN. THERE WL BE A GOOD SURGE OF CAA...FOCUSED ON THE MIDNGT-NOON TIME FRAME. HV WIND GUSTS UP TO 20KT DURING THIS PD...SPCLY FOR THE RDGTOPS AND WATER. A PD OF WAA LT WED NGT WL PROVIDE SOME ISENT LIFT. GDNC ATTEMPTING TO CRANK OUT A LTL QPF...AND CUDNT BACK AWAY FM CHC POPS FOR THE PTMC HIGHLANDS/CENTRAL SHEN VLY/CENTRAL FOOTHILLS. WL BE GOING W/ BKN CLDS AREAWIDE. AGAIN...MOST OF THIS WL BE FOCUSED ON THE OVNGT HRS. THE EVNG WL BE NO WORSE THAN PTCLDY. THERES GOOD AGREEMENT AMONGST MOS TEMP GDNC...AND HV TAKEN A BLEND OF OFFERINGS TO COMPOSE AN ENSEMBLE APPROACH. MIN-T MAY DROP INTO THE 40S IN THE APLCNS TNGT...50S ELSW. MAXT IN THE 70S TMRW...HIEST IN CENTRAL VA AND NEAR 70F ALONG THE MASON-DIXON. THE DISPARITY IS THE ZONE IN BTWN...AND WL BE WHERE ERRORS MAY BE THE GREATEST. WED NGT WL BE THE COOLEST OF THE STRETCH...MID 40S TO LWR 50S.
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&& .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... 12Z MODEL GUIDANCE STILL INDICATING SOME SPREAD IN THE HANDLING OF A SFC LOW ORGANIZING OVER THE SOUTHEASTERN US BY THURS MORNING. THE NAM REMAINS THE MORE PRONOUNCED IN PCPN DEVELOPMENT WITH THE GFS STILL ON THE DRIER SIDE. STILL SOME UNCERTAINTY ON THE TIMING AND EXTENT OF THE PCPN...THOUGH DO HAVE HIGHER CONFIDENCE OF PCPN IMPACTING AT LEAST SOUTHERN PORTIONS OF THE CWA DURING THE DAY THURSDAY SO CAPPED HIGH END CHC POPS THERE...WITH LOWER END SLIGHT CHC CLOSER NORTH NEAR THE MASON- DIXON. MOSTLY CLOUDY DAY EXPECTED WITH ELY FLOW...LIMITING INSTABILITY. WILL KEEP THUNDER OUT OF THE FORECAST FOR NOW. LOW PASSES OFF TO THE SOUTH AND EAST BY THURS NIGHT...TAPERING THE PCPN OFF WEST TO EAST. OVERALL EXPECTING THE PCPN TO BE CLEAR OF THE AREA BY FRI MORNING...THOUGH DEPENDING ON THE EXACT TRACK AND SPEED OF THE LOW...COULD SEE THE PCPN ENDING BY LATE THURS EVENING. HIGH PRESSURE BUILDING IN BEHIND THIS LOW WILL BRING ABOUT DRY CONDITIONS FRIDAY HEADING INTO THE WEEKEND. TEMPS HOVERING IN THE 60S ON THURS UNDER CLOUDY SKIES AND ELY FLOW. TEMPS JUMP INTO THE 70S FRI WITH MOSTLY SUNNY SKIES AND NW FLOW AIDING IN DOWNSLOPING AFFECTS. LOWS THURS RIGHT AROUND NORMAL...GENERALLY IN THE 50S...THOUGH COULD FLUCTUATE A COUPLE DEGREES DEPENDING ON HOW QUICKLY THE SKIES CLEAR. && .LONG TERM /SATURDAY THROUGH TUESDAY/... HIGH PRES OVER THE GREAT LAKES MOVES OVER PA FRI NIGHT INTO SAT AND THEN OFFSHORE SUN MORNING... A WARM FRONT LIFTS NORTH THROUGH THE OH VALLEY SUN INTO MON BRINGING A SLIGHT CHANCE OF SHOWERS AND TSTMS... SUN PRECIP IS EXPECTED MAINLY FOR AREAS N AND W OF THE CWA. PRECIP CHANCES INCREASE MON FOR MOST OF THE CWA AS WARM FRONT LIFTS NE. RETURN FLOW KEEPS CHANCES FOR SHOWERS AND TSTMS FOR TUES. TEMPS WILL BE NEAR NORMAL FOR SAT...UP TO TEN DEGREES ABOVE NORMAL FOR SUN AND MON... AND EVEN WARMER ON TUES. && .AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
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VFR CONDS XPCTD IN THE VALID TAF PD AND BYD. CLDS WL CONTINUE TO DSPT BY SUNSET...AND REMAIN NO WORSE THAN SCT THRU WED. LGT WLY WINDS WL INCR LT TNGT...CONTG THRU MIDDAY TMRW. G20 KT PSBL...BUT IT MAY BE PROBLEMATIC ACHIEVING IT AT THE TERMINALS. UPGLIDE WL RESULT IN A PD OF CLDS WED NGT...BUT MOST LKLY AFTER MIDNGT. CIGS WUD STILL BE VFR. MVFR CIGS PSBL THURS THRU THURS NIGHT WITH RAIN SHOWERS. LOW CONFIDENCE OF ISO TSTM...MAINLY THURS AFTN. VFR CONDITIONS RETURN BY FRI MORNING...CONTINUING THRU FRI NIGHT. WINDS LIGHT AND VRB THURS BCMG NW 5-10 KTS BY FRI MORNING. VFR CONDITIONS EXPECTED THIS WKND.
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&& .MARINE...
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WINDS LESS THAN 10 KT WL BECOME WLY/NWLY LT THIS EVNG AND INCREASE LT TNGT. WITHIN THE MIXED LYR...20 KT AVBL. LTST GDNC SUGGESTS ONSET MAY BE A BIT ERLR...AND HV BUMPED START TIME UP TO 1AM. THE GREATEST CVRG /AND CONFIDENCE/ WL BE AFTER SUNRISE THO. WINDS WL BE DECREASING WED AFTN...AND WL BE BACK DOWN BLO 10 KT LT WED NGT. SUB-SCA CONDITIONS THURSDAY WITH PSBL RAIN SHOWERS THROUGHOUT THE DAY. INCRSG NW WINDS FRI MORNING...WITH PSBL GUSTS 15- 20 KTS ON THE CHESAPEAKE BAY FRI. SUB-SCA CONDITIONS FRI NIGHT.
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&& .LWX WATCHES/WARNINGS/ADVISORIES... DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...SMALL CRAFT ADVISORY FROM 1 AM TO 5 PM EDT WEDNESDAY FOR ANZ530>543. && $$ SYNOPSIS...SEARS/HTS NEAR TERM...HAS/HTS SHORT TERM...SEARS LONG TERM...IMR AVIATION...SEARS/HAS/HTS MARINE...SEARS/HAS/HTS

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