Area Forecast Discussion
Issued by NWS Sterling, VA

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000
FXUS61 KLWX 301845
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
245 PM EDT SAT AUG 30 2014

.SYNOPSIS...
HIGH PRESSURE OFF CAPE COD WILL MOVE SOUTHEAST AND BECOME A
BERMUDA HIGH THROUGH TUESDAY. A COLD FRONT WILL CROSS THE AREA
TUESDAY NIGHT. HIGH PRESSURE WILL FOLLOW FOR THE SECOND HALF OF
THE WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
SFC HIPRES REMAINS OFF ACK TAFTN. HWVR...MRNG CLDS BROUGHT ONSHORE
ARND PERIPHERY OF HIGH HV HELD TOUGH ALONG AND E OF BLURDG...
TRAPPED UNDER H8 RDGG. LTST VSBL SATPIX DEPICT SOME CLRG ALONG
I-95. W OF THERE...IN THE LEE OF THE RDGS...A BKN TO ALMOST OVC
LYR OF CLDS REMAIN. TRENDS...AND LAV...SUGGEST THAT CLRG WL COME
DURING THE AFTN. OBVIOUSLY...THIS HAS HELD TEMPS DOWN. BUT WUD
XPCT A RAPID WARM UP ONCE INSOLATION APPEARS...AS THERES PLENTY OF
SNDG SUPPORT FOR IT.

MEANWHILE...AMPLE SUN IN THE PTMC HIGHLANDS HV LED TO DIURNAL CU.
LTST MESO GDNC RUNS STILL SUGGEST PCPN WL DVLP THERE...MID AFTN
INTO ELY EVNG. HWVR...SUPPORT TO ALLOW FOR THESE CELLS TO EMERGE
FM THE MTNS WL BE LACKING. HV OPTED TO SCALE BACK POPS OKV-MRB-
HGR. THE REST OF THE CWFA WL BE RAIN FREE THRU THE EVNG.

DP SWLY FLOW TNGT WL BRING THE HUMIDITY. THINK THAT/LL SUPPORT
PLENTY OF CLDS OVNGT. THE ADDED CLDCVR AND DEWPTS UP NEAR 70F
SUGGEST THAT WARMER MIN-T GDNC THE WAY TO GO. ALSO CANT RULE OUT
PATCHY FOG AS WE/LL BE QUITE SATD.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...

CWFA WL BE W/IN SWLY FLOW FOR THE FRIST PARTS OF THE WK. HWVR THE
FLOW WL BECOME A BIT MORE WLY MON...AND SPCLY TUE. THE PLUME OF
MSTR EVIDENT ON WATER VAPOR IMGRY WL BE RUNNING ATOP THE RDG.

LTST GDNC SUGGESTING THAT THE SETUP WONT BE QUITE AS IDEAL AS
PRVS CYCLES. THATS NOT TO SAY THERE WONT BE A MOIST/UNSTBL AMS.
BUT THTE RDG/ADVTN AS WELL AS PVA DURING THE AFTN WL BE BETTER IN
THE MTNS AND PTS WEST. STILL WL HV A CORRIDOR OF PWAT AOA 2
INCHES...BUT THERE/S NOT AS MUCH TO ORGANIZE/FORCE THE PCPN. AND
IN THE SERN CWFA...RDGG WL ACTUALLY SURPRESS IT. HV THEREFORE
BACKED OFF ON POPS SUN...STILL FOCUSING ON THE AFTN-EVE HRS. LKLY
POPS WONT APPEAR TIL EVNG...WHEN LIFT ARRIVES. NOCTURNAL STABILITY
WL ALLOW PVA TO SNEAK THRU OVNGT.

AM FCSTG A GOOD DEAL OF CLDCVR SUN...WHICH SHUD ONCE AGN IMPEDE
STRONG WARMING. HV SHADED DOWN MAXT A DEGF OR TWO.

WHILE THERE WL BE A SHARP LEE TROF MON...ALL OTHER FEATURES APPEAR
TO BE EITHER WEAK OR SUBTLE. WLY FLOW WL PROVIDE A LTL BIT OF
DRYING...WHICH IS EVIDENT IN PROGGED PWAT VALUES. THE IMPACT IS
EVIDENT IN POP VALUES...WHICH ARE LWR THAN SUN. THAT SEEMS QUITE
RESONABLE. AM GNLY IN THE 30-40 PCT RANGE...AND AM KEEPING A DRY
FCST IN CENTRL VA. WHATEVER TSRA THAT DO DVLP SHUD MV TO THE ERN
SHORE BY NIGHTFALL...AND HV A DRY FCST FOR MON NGT-- WHICH LARGELY
WL CONT INTO TUE DUE TO DOWNSLOPING.

THINK THAT THE BEST CHC AT A 90 DEG DAY WL COME ON TUE...AS WLY
FLOW WL KEEP POPS LOW AND PROVIDE COMPRESSIONAL WARMING. HV LWRD
MON MAXT BY A CPL...AND RAISED TUE MAXT ALSO BY A CPL. MIN-T FCSTS
ON TRACK...IN STEP W/ PROGGED DEWPTS.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
500MB SHORTWAVE WILL TRACK FROM THE GREAT LAKES TO SOUTHERN QUEBEC
AND DRAG A WEAK TROUGH THROUGH THE CWA TUESDAY NIGHT THROUGH
WEDNESDAY. 500MB HIGH WILL BUILD OVER MID ATLANTIC REGION WEDNESDAY
THROUGH THURSDAY. THE HIGH WILL WEAKEN ALLOWING A COLD FRONT TO
ENTER NORTHWEST PA BY SATURDAY NIGHT.

BAND OF MOISTURE...PVA...AND PASSAGE OF THE COLD FRONT WILL SUPPORT
A SLIGHT CHANCE DEVELOPMENT OF SHOWERS/THUNDERSTORMS TUESDAY NIGHT
THROUGH WEDNESDAY MORNING. MUCH DRIER AIRMASS ASSOCIATED WITH
SURFACE HIGH WILL CROSS THE CWA LATER WEDNESDAY THROUGH EARLY FRIDAY.
INCREASING MOISTURE DUE TO THE RETURN SOUTH TO SOUTHWEST FLOW
ASSOCIATED WITH THE HIGH AND PVA OUT AHEAD OF AN APPROACHING COLD
FRONT FROM THE WEST WILL SUPPORT AN INCREASED CHANCE OF MORE SHOWERS
AND THUNDERSTORMS SATURDAY.


&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
MVFR CIGS STILL HOLDING ON...AS MSTR TRAPPED BLO H8 INVRSN. AM
STILL HOPEFUL THAT RESTRICTIONS WL CLR BY MID AFTN.

SLY FLOW WL PROVIDE INCREASING LOW LVL HUMIDITY. THEREFORE...
OVERNIGHT FOG SHUD BE AN ISSUE. FLLWG CLIMO BY KEEPING DCA AT VFR.
OTRW...HV MVRG VSBYS ACRS THE BOARD PRE-DAWN. IFR A PSBLTY...BUT
THINK THERE WL BE TOO MUCH HIER LVL CLDCVR FOR THICKER FOG TO DVLP.

ONCE MRNG RESTRICTIONS CLR...ATM WL BE UNSTBL FOR SCT TSRA TO
DVLP. CUD HV LCL IFR IN HVR RAINERS...BUT LOW CONFIDENCE IN A SPOT
FCST PRECLUDE A TAF INCLUSION.

OUTLOOK...
MON...TARGETED IFR POSSIBLE AT TIMES WITH SCT TSRA. CVRG SHUD BE
LESS THAN SUN.
TUE-THU...PRIMARILY VFR.

&&

.MARINE...
SLY FLOW ACRS THE MARINE AREA THRU THE WKND. WITH DIURNAL MIXING...
INCRSD SPDS IN THE AFTN-EVE. SCA IN EFFECT LT TAFTN-TNGT FOR BAY
SANDY PT-SMITH PT DUE TO POTL OF 20 KT GUSTS. IT/LL BE A SIMLR
SITUATION SUNDAY...THO DONT THINK THE MIXING WL BE QUITE AS GOOD.
IN ADDITION...POTL TSRA WUD PROVIDE STRONGER WIND GUSTS.

OFFSHORE HIGH PRES WILL CONTINUE TO STEER WARM/HUMID AIR UP ACROSS
THE ERN SEABOARD. SETUP WUD SUPPORT PDS OF SLY CHANNELING...BUT
GDNC NOT PICKING UP ON ANY JUST YET. WK CDFNT LT TUE/ELY WED...
MARKED BY A SLGT SHIFT IN WIND DIRECTION FM SW TO NW.

&&

.TIDES/COASTAL FLOODING...
TIDAL DEPARTURES JUMPED UP YDA AFTN-EVNG. DEPARTURES HV BEEN
FAIRLY STEADY BTWN A 1/2 FT AND 1 FT ABV NORMAL. WINDS SHOULD
REMAIN SLY...SO ANTICIPATE ADDTL INCREASES THROUGH THE WKND. THE
NEXT HIGH TIDE /OVNGT INTO SUN MRNG/ WL NEED TO BE WATCHED FOR
POSSIBLE MINOR FLOODING. GDNC RIGHT NOW MAKING FOR A CLOSE CALL AT
ANNAPOLIS...BUT SUSPECT ITS OVERDONE BY A FEW INCHES. NONETHELESS...
THIS WL BE AN ISSUE THROUGH THE WKND.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...NONE.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SUNDAY FOR ANZ532>534.

&&

$$
SYNOPSIS...HTS
NEAR TERM...HTS
SHORT TERM...HTS
LONG TERM...MEADOWS
AVIATION...HTS
MARINE...HTS
TIDES/COASTAL FLOODING...HTS






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