Area Forecast Discussion
Issued by NWS Sterling, VA

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000 FXUS61 KLWX 280828 AFDLWX AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC 428 AM EDT THU MAY 28 2015 .SYNOPSIS... HIGH PRESSURE WILL REMAIN OFFSHORE THROUGH FRIDAY. A SOUTHERLY FLOW WILL BRING WARM HUMID CONDITIONS TO THE MID-ATLANTIC THROUGH SATURDAY. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE EACH AFTERNOON AND EVENING AS A SERIES OF COLD FRONTS APPROACH AND THEN DISSIPATE. A STRONGER COLD FRONT WILL ARRIVE SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... ANOTHER DAY OF SHOWERS AND TSTMS AS ANOTHER FRONTAL BOUNDARY SETS UP OVER THE REGION. HOWEVER...OVERALL EXPECTING LESS OF A SVR THREAT TODAY. LOW PRESSURE NORTH OF NEW ENGLAND WILL DRAG ITS ASSOCIATED COLD FRONT SOUTH INTO THE NORTHERN HALF OF THE CWA BY LATER THIS MORNING. EXPECTING THE FRONT TO BECOME NEARLY STATIONARY AS THE COMBINATION OF PERSISTING HIGH PRESSURE JUST OFFSHORE AND A BUILDING RIDGE LIMIT ANY FORWARD MOTION. THE FRONT REMAINS NEARLY STATIONARY DURING THE DAY...EVENTUALLY DISSIPATING BY TONIGHT. THIS FRONTAL BOUNDARY WILL ACT AS THE SFC TRIGGERING MECHANISM TODAY WITH UPPER LVL FORCING LACKING. ANOTHER DAY OF TEMPS PUSHING INTO THE 80S AND DEW PTS INTO THE 60S WILL RESULT IN DECENT INSTABILITY. SHEAR A BIT ON THE STRONGER SIDE TODAY...BUT STILL ON THE WEAKER SIDE...GENERALLY 20 KTS...SO OVERALL WHILE TSTM DEVELOPMENT IS EXPECTED...ANY SVR THREAT WILL BE MINIMAL. PWATS NOT QUITE AS HIGH TODAY BUT STILL HIGH ENOUGH SO THAT ANY TSTM COULD PRODUCE A BRIEF PERIOD OF HEAVIER RAIN. ALSO UNLIKE YESTERDAY WITH A LINE FORMATION...EXPECTING ACTIVITY TODAY TO BE MORE SCT IN NATURE...SO HAVE CAPPED POPS AT HIGH END CHC TO ACCOUNT FOR THE UNCERTAINTY OF WHERE EXACTLY THE STORMS WILL DEVELOP. THE BETTER CHC IS OVER NORTHERN AREAS CLOSER TO THE FRONTAL BOUNDARY INITIALLY TODAY...WITH THE PCPN PUSHING SOUTH BY THIS EVENING. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... SHOWERS AND TSTMS CONTINUE THIS EVENING WITH STILL ENOUGH INSTABILITY LINGERING...BUT ALSO NOW AIDED BY A PASSING WEAK SHORTWAVE. THE PCPN TAPERS OFF BY THE SECOND HALF OF THE NIGHT WITH THE LOSS OF THE BOUNDARY...INSTABILITY AND UPPER LVL FORCING. DRY PERIOD THEN THRU DAYBREAK BEFORE YET ANOTHER ROUND OF PCPN. ANOTHER SINKING COLD FRONT NEARS THE REGION...THOUGH WEAKENING AS IT SETTLES ALONG THE MASON DIXON LINE WITH THE SFC HIGH AND RIDGE ALOFT STALLING ANY FORWARD PROGRESSION. HAVE SLIGHT CHC POPS IN THE MORNING TO ACCOUNT FOR ANY DEVELOPMENT ALONG THIS FRONTAL BOUNDARY...THEN INCREASED TO CHC FOR THE AFTN AS A PASSING SHORTWAVE COULD TRIGGER SCT ACTIVITY. THINKING THE BETTER CHC ON FRI WILL BE FOR WESTERN AREAS CLOSER TO THE FORCING ALOFT. LOSS OF DAYTIME HEATING AND FORCING SHOULD KEEP THINGS MAINLY DRY FRI NIGHT...ESP BY THE SECOND HALF OF THE NIGHT. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... CWFA WL BE WELL WITHIN THE WARM SECTOR SAT AS STRONG RDGG SFC-H5 RESIDES OFF THE EASTERN SEABOARD. MDT-HIGH INSTBY VALUES/LAPSE RATES WL BE SLIDING UP THE BACK SIDE OF THE RDG...WHICH MAINLY WL ENCOMPASS THE PTMC HIGHLANDS BUT THE ERN PERIPHERY MAY INCL THE BLURDG. WIND FIELDS LCLLY WL BE INCRSG...WHICH MAY SUPPORT A FEW STRONGER TSTMS. IN ADDITION...THE MSTR PLUME WL BE COMING OFF THE GLFMEX W/ PWAT AOA 1.5 INCHES...SO ANY STORM CUD BE A HVY RAINER AS WELL. THE RDG WL BEGIN TO BREAK DOWN SAT NGT...AND WL CONT TO DO SO THRU SUN. THIS WL BE ENUF TO ALLOW CDFNT TO SAG INTO CWFA. SINCE NRN STREAM SUPPORT WL EJECT WELL INTO THE CNDN MARITIMES...ORIENTATION OF THE FNT WL PERMIT TRAINING CELLS. THINK THE RAFL WL BECOME THE BIGGER DEAL...BUT GFS/ECMWF STILL DEPICTING SPREAD OF SOLNS...SO CONFIDENCE LOW ON SPECIFICS. ENUF EVIDENCE FOR LKLY POPS THO. MDL SPREAD MANIFESTS ITSELF MORE MON-TUE. HIPRES RDGG SWD FM QUE WL CARRY COOL AIR W/ IT...AND WUD SUPPORT MARITIME FLOW FOR CWFA. MEANWHILE...FNTL BNDRY SHUD BE NEARBY AND PROVIDE SOME OVERRUNNING. TEMP FCST FOR MON QUITE A BIT COOLER BECAUSE OF THIS. FURTHER...HV REMOVED MENTION OF THUNDER AS AMS SHUD HV STABILIZED. CONFIDENCE RATHER LOW ON THE MAGNITUDE OF THE CAA. H5 HGT PTTN ACRS THE CONUS FOR THE WEEK AHD FEATURES BROAD RDGG BUT W/ A CUTOFF LOW MEADERING ACRS THE SE. AM UNSURE OF IMPACT...BUT RANGE OF PSBLTYS RELUCTANTLY SUGGESTS POPS NEED TO STAY IN PLACE. && .AVIATION /09Z THURSDAY THROUGH MONDAY/... GENERALLY VFR CONDITIONS TODAY. MID-HIGH LVL CLOUDS EXPECTED THRU THE PERIOD WITH SCT CU FORMING TODAY. PATCHY FOG PSBL EARLY THIS MORNING COULD BRING VIS DOWN 3-4SM...THOUGH LOW CONFIDENCE ON THIS FOR AS SKY COVERAGE IS INCRSG. ANY FOG THAT DOES FORM WILL DISSIPATE SOON AFTR DAYBREAK. CHC FOR AFTN SHOWERS AND TSTMS AT ALL TAF SITES. HAVE INCLUDED WITH VCSH FOR NOW DUE TO THE SCT NATURE AND THE HIGH UNCERTAINTY OF EXACT TIMING AND PLACEMENT OF THE STORMS. SOME OF THE TAF SITES COULD SEE MULTIPLE STORMS COME THRU DURING THE AFTN. NOT EXPECTING SVR LVLS...BUT CANNOT RULE OUT GUSTY WINDS AND BRIEF HEAVY RAINFALL DROPPING VIS TO SUB-VFR. ANY PCPN THREAT ENDS OVERNIGHT...WITH ANOTHER ROUND OF PCPN PSBL ON FRI. WINDS GENERALLY LIGHT AND VRB THRU TONIGHT. ELY TO SELY FLOW TOMORROW 5-10KTS. BRIEF FLGT RESTRICTIONS PSBL SAT PM INVOF TSRA. MRB HAS BEST CHC AT BEING AFFECTED. CDFNT WL DROP SWD SUN PROVIDING A GREATER RISK OF TSRA AREAWIDE. SPORADIC RESTRICTIONS CONT INTO MON. IFR PSBL IF MARINE AMS SPREADS INLAND. && .MARINE...
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HAVE CANCELLED THE LAST TWO ZONES OF THE SCA WITH WINDS GENERALLY 15 KTS OR LESS. SUB-SCA CONDITIONS NOW EXPECTED ON ALL WATERS THRU FRI NIGHT. CHC OF TSTMS THIS AFTN AND THEN AGAIN FRI AFTN COULD BRING A PERIOD OF GUSTIER WINDS. SWLY FLOW INCREASES SAT-SAT NGT...PROVIDING THE NEXT POTENTIAL ROUND OF SCA CONDS. A FEW STRONG TSRA WL BE POSSIBLE DURING THE AFTN- EVNG...BUT STORMS WL BE MORE NMRS SUNDAY. STRONG SUSTAINED WINDS WL BE REPLACED BY LCLLY STRONG GUSTS AT THAT TIME.
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&& .LWX WATCHES/WARNINGS/ADVISORIES...
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DC...NONE. MD...NONE. VA...NONE. WV...NONE. MARINE...NONE.
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&& $$ SYNOPSIS...HTS NEAR TERM...SEARS SHORT TERM...SEARS LONG TERM...HTS AVIATION...SEARS/HTS MARINE...SEARS/HTS

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