Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 280741
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
341 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 /08Z 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...
SCA REMAINS IN EFFECT FOR THE MIDDLE CHESAPEAKE BAY ZONE THRU
10Z. SUB-SCA CONDITIONS THEN 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.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT EARLY THIS MORNING FOR
     ANZ534-543.

&&

$$
SYNOPSIS...HTS
NEAR TERM...SEARS
SHORT TERM...SEARS
LONG TERM...HTS
AVIATION...SEARS/HTS
MARINE...SEARS/HTS


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