Office: LWX

FXUS61 KLWX 240821
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
421 AM EDT WED SEP 24 2008

.SYNOPSIS...
HIGH PRESSURE OVER NEW ENGLAND AND LOW PRESSURE OFF THE CAROLINA
COAST WILL BRING A PROLONGED EASTERLY FLOW THROUGH THE REST OF THE
WEEK. THIS WILL BRING SOME RAIN AND GUSTY WINDS TO THE MID
ATLANTIC REGION THURSDAY INTO FRIDAY. SOME OF THE RAIN COULD
LINGER INTO THE WEEKEND AS LOW PRESSURE GRADUALLY MOVES UP THE NEW
ENGLAND COAST.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
SURFACE ANALYSIS EARLY THIS MORNING INDICATED HIGH PRESSURE PARKED
OVER NEW ENGLAND WHILE LOW PRESSURE WAS SPINNING OFF THE CAROLINA
COAST. GIVEN THE DRYING OVER THE PAST 24 HOURS...STRATOCU ARE NOT A
PROBLEM EARLY THIS MORNING AS THEY WERE YESTERDAY MORNING.
HOWEVER...UNDER CLEAR SKIES...LOCALIZED FOG WAS BEGINNING TO FORM
MAINLY IN THE TYPICAL RADIATION/GROUND FOG SPOTS.

MODELS KEEP THE MAGNITUDE OF HIGH PRESSURE ABOUT THE SAME TODAY...AS
ITS CENTER SHIFTS OFF THE NEW ENGLAND COAST. MEANWHILE...MODELS ARE
IN AGREEMENT WITH PRESSURE FALLS OFF THE CAROLINA COAST AS LOW
PRESSURE DEEPENS. THIS WILL STIFFEN THE EASTERLY GRADIENT TODAY.

MODELS MAY BE A TAD TOO SLOW WITH BRINGING IN INCREASED RH
INDICATIVE OF CIRRUS...BUT THINK THAT MOST OF THIS WILL HOLD OFF
UNTIL THIS EVENING. THEREFORE...WILL FAVOR MOSTLY SUNNY SKIES TODAY.
THIS WILL BOOST TEMPERATURES INTO THE MID 70S FOR MOST
LOCALES...EXCEPT NEAR THE BAY AND OVER THE MOUNTAINS WHERE MAX T
SHOULD FALL A LITTLE SHORT OF MID 70S.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM THURSDAY/...
CLOUDS...INITIALLY CIRRUS...WILL SPREAD NORTHWEST ACROSS THE CWA
OVERNIGHT. FOLLOWED 21Z SREFS FOR CHANCES OF MEASURABLE
PRECIP...WHICH KEEPS MOST OF THE CWA DRY OVERNIGHT. EXCEPTION IS
ACROSS LOWER SOUTHERN MARYLAND WHERE RAIN MAY BEGIN TO DEVELOP LATE.
EASTERLY GRADIENT WILL TIGHTEN FURTHER...KEEPING SOME WIND
OVERNIGHT.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
LOW PRES IS BEGINNING TO ORGANIZE ABOUT 200 NMI OFF THE NC COAST.
THIS STORM SYSTEM IS FCST TO RETROGRADE AND MOVE INLAND INTO THE
CAROLINAS THU NIGHT. TIGHTENING PRES GRADIENT BETWEEN THE HIGH OVER
NEW ENGLAND AND THIS LOW WILL CREATE WINDY CONDITIONS ESPECIALLY
EAST OF I-95 CORRIDOR. STRONG ONSHORE FLOW WILL ALSO DRAW IN PLENTY
OF ATLC MOISTURE. GFS SHOWS WIDESPREAD 1.0+ INCH TOTALS WITH UP TO
2.5 INCHES CLOSER TO THE PA BORDER. HEAVIEST RAINS EXPECTED THU
AFTERNOON-EVENING. MID-UPPER LVL SYSTEM WILL LIFT SLOWLY NORTH ON
SAT WITH ONSHORE FLOW WEAKENING. HOWEVER...OVERCAST CONDITIONS ALONG
WITH OCCASIONAL LIGHT RAIN OR DRIZZLE WILL PERSIST AT LEAST UNTIL
MIDDAY SAT. PERHAPS A FEW GLIMPSES OF SAT AFTERNOON. DRY WEATHER AND
SUNSHINE WILL RETURN ON SUN AS STORM SYSTEM DEPARTS TO THE NORTH AND
SFC WINDS BECOME WESTERLY.

GFS SHOWS 40+KT H5 METER WINDS AGL AS FAR WEST AS THE I-95 CORRIDOR
WITH AN AREA OF 45+KT GUSTS OVER CALVERT AND ST. MARYS COUNTIES THU
AFTERNOON. LOOKS LIKE WE WOULD NEED A WIND ADVISORY AT LEAST FOR
THESE TWO COUNTIES PERHAPS AS FAR WEST AS THE I-95 CORRIDOR ALTHOUGH
NOT AS CONFIDENT ON THIS. BUT THIS ONLY LOOKS TO BE LIKE A 6-HR
PERIOD OF STRONG WINDS.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
06Z TAF ISSUANCE FEATURED MAINLY VFR CONDITIONS...SAVE FOR A
TEMPORARY PERIOD OF MVFR FOG AT KMRB UNTIL 12Z. EASTERLY FLOW WILL
CONTINUE THROUGH TONIGHT...WITH GUSTS AOA 20 KT DURING THE
AFTERNOON.

CONDITIONS EXPECTED TO DROP INTO THE MVFR CATEGORY BY 18Z THU IN
RAIN AND DROP INTO THE IFR CATEGORY BY 06Z FRI. IFR CONDITIONS ALONG
WITH OCCASIONAL LIGHT RAIN WILL PERSIST THROUGH MIDDAY SAT.
CONDITIONS NOT EXPECTED TO IMPROVE TO VFR UNTIL MIDDAY SUN.
STRONGEST WIND GUSTS IN THE RANGE OF 30-40KT MAINLY THU
AFTERNOON-EVENING.

&&

.MARINE...
EARLY THIS MORNING...CONDITIONS VARIED GREATLY ACROSS THE MARINE
WATERS. SOLID SMALL CRAFT ADVISORY CRITERIA /G25 KT/ WAS BEING
OBSERVED NEAR THE POTOMAC/BAY JUNCTION WHILE WINDS ON THE ORDER OF 5
TO 10 KT WERE BEING OBSERVED ACROSS THE NORTHERN BAY AND UPPER
POTOMAC. THE TREND THROUGH TONIGHT WILL BE FOR INCREASING
WINDS...FIRST NEAR THE POTOMAC/BAY JUNCTION AND THEN FURTHER NORTH
AND WEST...AS THE EASTERLY GRADIENT TIGHTENS. HAVE ATTEMPTED TO
CAPTURE TEMPORALLY SIGNIFICANT THRESHOLD TRENDS IN THE LATEST HAZARD
GRIDS...RAMPING UP SMALL CRAFT ADVISORIES TO GALE WARNINGS ACROSS
THE LOWER POTOMAC AND MID BAY TONIGHT.

GALE CONDITIONS EXPECTED THU-THU NIGHT ALL WATERS. STRONGEST WINDS
EXPECTED THU AFTERNOON WITH GUSTS UP TO 45 KT MAINLY S OF COBB
ISLAND ON THE POTOMAC AND S OF NORTH BEACH ON THE CHES BAY. WINDS
WILL BEGIN TO SLOWLY DECREASE AFTER 06Z FRI AS GRADIENT RELAXES A
BIT AND INVERSION STRENGTHENS. GUSTS EXPECTED TO DROP BELOW SCA FRI
NIGHT.

&&

.TIDES/COASTAL FLOODING...
EARLY THIS MORNING...WATER LEVELS WERE GENERALLY RUNNING 0.75 TO
1.00 FEET ABOVE NORMAL. WITH EASTERLY FLOW CONTINUING THROUGH
THURSDAY NIGHT...THESE ANOMALIES ARE FORECAST TO INCREASE...WHERE
WATER LEVELS MAY RUN 2 TO 3 FEET ABOVE ASTRONOMICAL PREDICTIONS.

ACCORDING TO THE EXTRATROPICAL STORM SURGE MODEL...THE FIRST HIGH
TIDE THAT MAY BE IMPACTED WITH AT LEAST MINOR TIDAL FLOODING WILL BE
THE ONE TONIGHT INTO EARLY THURSDAY MORNING. THIS IS BEYOND 12
HOURS...SO NO COASTAL FLOOD ADVISORY WILL BE ISSUED. A COASTAL FLOOD
WATCH IS ALREADY IN EFFECT FOR SOME COUNTIES ADJACENT TO THE WESTERN
SHORE FOR TONIGHT AND CONTINUING THROUGH THURSDAY NIGHT WHICH
INCLUDES A COUPLE OF ADDITIONAL HIGH TIDES THAT COULD FLIRT WITH
MODERATE TIDAL FLOODING. HAVE EXPANDED THIS WATCH FURTHER NORTH TO
INCLUDE BALTIMORE/HARFORD COUNTIES GIVEN PROJECTIONS FOR BALTIMORE
FROM THE EXTRATROPICAL MODEL.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...COASTAL FLOOD WATCH FROM LATE TONIGHT THROUGH LATE THURSDAY
     NIGHT FOR MDZ007-011-014-017-018.
VA...NONE.
WV...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EDT THURSDAY FOR ANZ530>532-
     535-536.
     GALE WARNING FROM 6 AM THURSDAY TO 6 AM EDT FRIDAY FOR
     ANZ530>532-535-536.
     SMALL CRAFT ADVISORY UNTIL 6 PM EDT THIS AFTERNOON FOR ANZ533-
     534-537.
     GALE WARNING FROM 6 PM THIS EVENING TO 6 AM EDT FRIDAY FOR
     ANZ533-534-537.

&&

$$
SYNOPSIS...PELOQUIN
NEAR TERM...PELOQUIN
SHORT TERM...PELOQUIN
LONG TERM...ROSA
AVIATION...PELOQUIN/ROSA
MARINE...PELOQUIN/ROSA