Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 310739
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
339 AM EDT THU JUL 31 2014

.SYNOPSIS...
SURFACE HIGH PRESSURE REMAINS OVER THE WESTERN ATLANTIC...AND WILL
SPREAD ITS INFLUENCE INLAND. MEANWHILE...UPPER LEVEL LOW PRESSURE
OVER EASTERN ONTARIO CONTINUES TO SEND UPPER LEVEL DISTURBANCES
EASTWARD. A COASTAL FRONT WILL DEVELOP FRIDAY NIGHT...LASTING
THROUGH THIS WEEKEND INTO EARLY NEXT WEEK.
&&

.NEAR TERM /THROUGH TONIGHT/...
LTST SFC ANALY DEPICTS BROAD HIPRES ALONG THE ERN SEABRD OF THE
CONUS...WITH LOPRES N OF THE GRTLKS. THE LOW IS AN ARTIFACT OF THE
LINGERING ULVL CYCLONE...WHICH IS ROTATING SPOKES OF PVA ACRS THE
GRTLKS TWD NEW ENGLAND AND THE MID ATLC. ONE SUCH VORT...EVIDENT ON
WATER VAPOR...DEPARTING NERN MD ATTM. THERE HV BEEN A FEW ASSOCD
SPRINKLES THRU THE NGT...BUT THE PREDAWN HRS SHUD BE DRY...AS RECENT
RDR TRENDS HV BEEN DECLINING...W/ THE NEAREST COLD CLD TOPS HEADED
TWD BUF. WL STILL HV INTERVALS OF CLDS THRU SUNRISE.

THRU THE DAYTIME HRS TDA...THE RDG FM THE ATLC WL GNLY BE THE
CONTROLLING WX FACTOR. FORCING NIL AT BEST...AND INSTBY VALUES
MEAGER. AM CARRYING A DRY FCST W/ MOSUN OR SUNNY SKIES. DUE TO THIS
INSOLATION AND WAA...MAXT WL BE WARMER THAN RECENT PAST. MOS GDNC IN
GNRL AGREEMENT...AND BLEND TAKEN.

THTE RDGG AND MID-LVL CNVGNC INCR TNGT. THUS...WUD ANTICIPATE BLDG
MID DECK CLDS...RISING DEWPTS AND POTL CRRDR OF PCPN. BOTH NAM/GFS
HV THIS...THO THE NAM SEEMS EXCESSIVELY WET FOR THE SITUATION. HV
SIDED W/ GFS...WHICH BRINGS CHC POPS JUST E OF THE SPINE OF THE
BLURDG PAST CHO TWD DC. LLVL WNDS IN THIS AREA SELY ARND PERIPHERY
OF RDG...WHICH WUD ADD A LTL UPSLOPE SUPPORT FOR PCPN DVLPMNT. QPF
LGT...AND AM KEEPING POPS NO HIER THAN 30 PCT...GNLY LT NGT/OVNGT
HRS. SINCE DEWPTS SHUD BE ABLE TO CRACK THE 60 DEGF BARRIER...MIN-T
WL BE IN THE 60S...AND A BIT HIER THAN THAT FOR DCA/DMH.
&&

.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
PTTN CHG WL MANIFEST ITSELF FRI...AS H9-7 CONFLUENCE WL COAX GLFMEX
MSTR NEWD. WL STILL HV A THTE RDG SITUATED OVER THE MTNS...SO A
CRRDR OF FVRBL ISENT UPGLIDE WL RESIDE COINDICENT W/ LLVL LIFT. WL
RAISE POPS TO LKLY BY AFTN. SNDGS LOOK FAIRLY SATD THRUT...AND AM
OVERALL NOT TOO IMPRESSED BY CNVCTV POTL-- SHRA NOT TSRA.

A CSTL FNT MAY DVLP BY EVNG...W/ A S/WV RIDING NWD LT NGT. GDNC
STRUGGLING A BIT W/ ITS DVLPMNT/PLACEMENT VS RDGG ON THE BACK SIDE
DOWN THE I-95 CRRDR. THAT WL DICATE PCPN TIMING FRI NGT. THTE SEEMS
TO BE SHUNTED TWD THE CST...AND SINCE FRONTOGENESIS PLAUSIBLE...WL
AIM POPS THAT WAY.

PER TEMPS...MAXT FRI WL BE HELD DOWN BY CLDS AND PSBL PCPN. MOST
GDNC SUGGESTING UPR 70S/LWR 80S. ECMWF DISTINCTLY LWR...SPCLY IN
CENTRL SHEN VLY AND PTMC HIGHLANDS. HV MINIMZED RANGE FOR MIN-T FRI
NGT DUE TO WET AMS. DEWPTS LED THE WAY.
&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
THE MID-ATLANTIC WILL CONTINUE TO BE INFLUENCED BY CYCLONIC FLOW
ALOFT THROUGH THE LONG TERM. AN UPPER LEVEL TROUGH WILL APPROACH
THE OHIO VALLEY SATURDAY. HIGH PRESSURE IS EXPECTED TO LIFT TO
THE NORTHERN ATLANTIC WHILE A COASTAL FRONT REMAINS ALONG THE EAST
COAST. SHOWERS WILL BE POSSIBLE ALONG THE FRONTAL BOUNDARY NEAR
THE CHESAPEAKE BAY SATURDAY. SHOWERS AND THUNDERSTORMS WILL ALSO
BE POSSIBLE ACROSS THE OHIO VALLEY AND WEST OF THE BLUE RIDGE
SATURDAY AFTERNOON AS THIS REGION WILL GAIN INSTABILITY THROUGHOUT
THE DAY. THE TROUGH WILL APPROACH THE MID-ATLANTIC SUNDAY AND
LARGE SCALE FORCING WILL INCREASE ACROSS THE REGION AS PVA
INCREASES AND THE ENTRANCE REGION OF THE JET MOVES CLOSE BY.
SOUTHERLY FLOW WILL CONTINUE TO DRAW MOISTURE INTO THE REGION AND
SHOWERS AND THUNDERSTORMS ARE EXPECTED. A WEAK FRONT WILL CROSS
THE REGION SUNDAY NIGHT INTO MONDAY AND SHOWERS SHOULD MOVE TO THE
EAST BY MONDAY MIDDAY. FCST MAX TEMPS WILL BE BELOW NORMAL THIS
WEEKEND...IN THE LOW TO MID 80S.

THE START OF THE WORK WEEK LOOKS QUIET AT THIS TIME AS HIGH
PRESSURE MOVES IN BEHIND THE WEAK COLD FRONT. BY WEDNESDAY AND
THURSDAY...RETURN FLOW BEGINS AND SHOWERS AND THUNDERSTORMS WILL
BE POSSIBLE. FCST MAX TEMPS WILL BE NEAR NORMAL NEXT WEEK.
&&

.AVIATION /08Z THURSDAY THROUGH MONDAY/...
VFR CONDS XPCTD TDA-TNGT. THERE ARE PATCHES OF FOG PRESENT ATTM. DO
NOT BELIEVE THAT ANY WL DVLP OVER TERMINALS FOR MRNG PUSH. IF
INCORRECT...THEN FLGT RESTRICTIONS PLAUSIBLY CUD BRIEFLY REACH IFR.
LATER TDA...CU WL DVLP...BASES 050-070. THESE WL THICKEN TNGT...W/
CIGS FCST AT SAME RNG. FOG WL AGN BE A WILD CARD PREDAWN TMRW...BUT
SO MAY SCT SHRA. DUE TO LOW CONFIDENCE...WL BE KEEPING VFR FCST.

MSTR PROFILE INCREASES FRI-FRI NGT...SO SHRA CHCS INCR. THESE MAY
PROMPT FLGT RESTRICTIONS...W/ PDS VFR IN BTWN.

SHRA/TSRA POSSIBLE SATURDAY AFTERNOON AND SUNDAY AS AN UPPER LEVEL
DISTURBANCE APPROACHES. MVFR POSSIBLE EARLY SUNDAY MORNING. HIGH
PRESSURE MOVES INTO THE REGION FOR THE START OF NEXT WORK WEEK.
&&

.MARINE...
SLY FLOW MAINLY AOB 10 KT ATTM. TPLM2 PROVING TO BE THE EXCEPTION...
AS SENSOR ABLE TO TAP WNDS FM LLJ NEAR 15 KT. WL CONT TO MONITOR...
BUT WRF-ARW4 GDNC SUGGESTING WNDS WL REMAIN BLO SCA THRESHOLDS.

ONCE WNDS SUBSIDE BY DAWN...AOB 10 KT SLY FLOW REMAIN THRU THE
DAY. LLJ INCR ONCE TNGT. NOT SOLD ON SCA CONDS YET...BUT WRF
SUGGESTING WL HV A BETTER CHC AT IT. HV CAPPED GRIDS BLO SCA...BUT
ITS NOT OUT OF THE REALM OF PSBLTYS.

WNDS BACK ELY FRI-FRI NGT. SPDS NOT A FACTOR...MAINLY BLO 10 KT.
PCPN CHCS DO INCR...WHICH WUD OBSTRUCT VSBY.

A COASTAL FRONT WILL REMAIN NEAR THE CHESAPEAKE BAY SATURDAY AND
SUNDAY BEFORE A WEAK COLD FRONT MOVES THROUGH THE REGION FROM THE
WEST. SHOWERS AND ISO THUNDERSTORMS POSSIBLE ON THE WATERS DURING
THIS TIME.
&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...NONE.

&&

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







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