FXUS61 KLWX 100110
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
800 PM EST WED DEC 9 2009
.SYNOPSIS/UPDATE...
FAIRLY STG GRADIENT CONTS BETWEEN SFC LOW PRES OVR ERN CANADA AND
HIGH PRES WELL WEST OF THE REGION. ENOUGH TO WARRANT MAINTAINING
WIND ADVISORY UNTIL AT LEAST 1AM EXPIRATION IF NOT BEYOND. WILL LET
MID SHIFT ASSESS NEED FOR EXTENSION BASED ON OBS AT THE TIME.
HIGH WIND WARNING FOR FAR WEST ZONES WAS ALLOWED TO EXPIRE AT 7PM.
WINDS BELOW CRITERIA AND NOT EXPECTED TO INCREASE OVERNIGHT.
MARINE FLAGS...NO CHG.
PUBLIC FCST...AM YANKING FIRST PERIOD POPS EXCEPT FOR UPSLOPE
REGIONS IN THE FAR W.
&&
.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
STRONG SYSTEM CONTINUES TO BRING BUSY WEATHER TO THE MID ATLANTIC
THIS AFTERNOON AND EVENING. THE COLD FRONT CURRENTLY STRETCHES FROM
WESTERN PA BACK THROUGH CENTRAL WEST VIRGINIA ALL THE WAY BACK DOWN
TO THE GULF COAST. STRONG WINDS HAVE DEVELOPED BEHIND THE
BOUNDARY...WITH GUSTS AS HIGH AS AROUND 55 KT NOTED IN WEST
VIRGINIA. SOME OF THE HIGHER GUSTS HAVE BEEN IN SHOWERS...BUT SOME
OF THE GUSTS ARE GRADIENT WINDS. REGIONAL RADAR LOOPS SHOWS SOME
SHOWERS AND ISOLATED THUNDERSTORMS ASSOCIATED WITH THE FRONT...AND
THESE WILL CONTINUE TO PUSH EASTWARD THIS EVENING.
UPSLOPE SNOW SHOWERS ARE POSSIBLE BEHIND THE FRONT OVERNIGHT...BUT
WIND TRAJECTORY WILL REMAIN MORE WESTERLY THAN NORTHWESTERLY. WITH
THE MORE WESTERLY TRAJECTORY...NOT EXPECTING SIGNIFICANT
ACCUMULATING SNOWFALL ALONG THE WESTERN SLOPES...POSSIBLY AROUND AN
INCH TO JUST UNDER AN INCH AND A HALF.
HAVE ISSUED A HIGH WIND WARNING FOR THE FAR WESTERN COUNTIES FOR
THIS AFTERNOON AND EARLY EVENING...AS WIND GUSTS TO 60 MPH WILL BE
POSSIBLE. A WIND ADVISORY REMAINS IN EFFECT FOR THE REMAINDER OF THE
AREA UNTIL 1 AM...INCLUDING HIGH WIND WARNING AREA AFTER 7 PM.
SMALL HAIL WILL BE POSSIBLE WITHIN THE STRONGER SHOWERS AND ISOLATED
THUNDERSTORMS.
&&
.SHORT TERM /6 AM THURSDAY MORNING THROUGH 6 PM THURSDAY/...
HIGH PRESSURE BUILDS EAST DURING THE DAY TOMORROW...WITH SUNNY SKIES
AND COOLER MAX TEMPS. WINDS ALOFT WILL CONTINUE TO BRING WIND GUSTS
BETWEEN 25 AND 30 KT TO THE AREA.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
STRONG CAA CONTINUES THU NGT THRU SAT...AS 1030MB SFC RIDGE SLIDES
SEWD INTO SERN CONUS. WITH CLOSED LOW OFF CANADIAN MARITIMES...PRES
GRADIENT WILL BE TIGHT...WITH GUSTY NW WINDS XPCD THRU THE PERIOD.
AFTN MAXIMA STRUGGLE TO REACH FREEZING...WITH LOWS IN THE TEENS MANY
AREAS WEST OF INTERSTATE 95. THU NGT XPCT THAT WIND CHILL ADVISORY
WILL BE NECESSARY OVER THE POTOMAC HIGHLANDS...AS NW WINDS OF 20 TO
30 MPH AND TEMPS FALLING INTO THE SINGLE DIGITS WILL PRODUCE WIND
CHILL INDICES BELOW ZERO.
WEAK SHRTWV PASSES N OF THE AREA SAT NGT/SUN...PROMPTING
CYCLOGENESIS OFF CAROLINA COAST. MODELS TRENDING LESS ROBUST WITH
MOISTURE AND DEPTH OF COLD AIR OVR MID ATLANTIC IN RECENT RUNS...SO
WILL KEEP PRECIP CHANCES AOB 40 PERCENT FOR NOW. ANOTHER STORM
SYSTEM LOOKS TO AFFECT THE AREA TUESDAY.
&&
.AVIATION /20Z WEDNESDAY THROUGH MONDAY/...
MVFR CIGS ARE EXPECTED FOR THE TERMINALS THIS EVENING. THE MAIN
ISSUE WILL BE THE WINDS. THE GRADIENT HAS TIGHTENED AROUND A STRONG
LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES...LEADING TO VERY GUSTY
WINDS. WIND GUSTS TO BETWEEN 35 AND 40 KT WILL BE POSSIBLE AT THE
AIRPORTS OVERNIGHT. WITHIN ANY SHOWERS AND POSSIBLE
THUNDERSTORMS...WIND GUSTS COULD EVEN BE HIGHER.
WINDS WILL SHIFT AROUND FROM THE SOUTH TO THE WEST/SOUTHWEST BEHIND
THE FRONT OVERNIGHT. CIGS SHOULD SCATTERED OUT AROUND
MIDNIGHT...SHOULD BE TOO WINDY FOR FOG DEVELOPMENT.
VFR CONDS XPCD THU NGT THRU SAT. NEXT CHANCE OF SUB-VFR CIG/VSBY SAT
NGT INTO SUNDAY AS LOW PRESSURE AFFECTS THE AREA.
&&
.MARINE...
HAVE RAISED A GALE WARNING FOR THE ENTIRE MARINE AREA FOR THE
OVERNIGHT HOURS. GRADIENT WINDS HAVE INCREASED AROUND A STRONG LOW
PRESSURE SYSTEM LOCATED OVER THE GREAT LAKES. WIND GUSTS AROUND 35
KT WILL BE LIKELY OVERNIGHT...WITH SOME HIGHER GUSTS WITHIN SHOWERS.
S/SW WINDS ARE EXPECTED. WEST WINDS WILL BE THE RULE ON
THURSDAY...WITH SMALL CRAFT CONDITIONS CONTINUING.
TIGHT PRESSURE GRADIENT AND CAA WILL KEEP STRONG WINDS OVER THE
WATERS THU NIGHT...SMALL CRAFT ADVISORY CONTINUES. SIMILAR
CONDITIONS XPCD FRI...BEFORE HIPRES MOVES OVER THE WATERS FRI NGT
AND SAT...BRINGING LIGHTER WINDS
&&
.TIDES/COASTAL FLOODING...
WATER LEVELS REMAIN ELEVATED ACROSS THE TIDAL POTOMAC AND WESTERN
SHORE OF THE CHESAPEAKE BAY THIS AFTERNOON. BELIEVE THE ELEVATED
WATER LEVELS WILL CONTINUE THROUGH THE NEXT HIGH TIDE CYCLE
OVERNIGHT AND EARLY TOMORROW MORNING.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...WIND ADVISORY UNTIL 1 AM EST THURSDAY FOR DCZ001.
COASTAL FLOOD ADVISORY UNTIL 7 AM EST THURSDAY FOR DCZ001.
MD...WIND ADVISORY UNTIL 1 AM EST THURSDAY FOR MDZ004>007-009>011-
013-014-016>018.
COASTAL FLOOD ADVISORY UNTIL 7 AM EST THURSDAY FOR MDZ007-011-
013-014-016>018.
HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR MDZ501-502.
WIND ADVISORY FROM 7 PM THIS EVENING TO 1 AM EST THURSDAY FOR
MDZ501-502.
WIND ADVISORY UNTIL 1 AM EST THURSDAY FOR MDZ003.
VA...WIND ADVISORY UNTIL 1 AM EST THURSDAY FOR VAZ036>042-050>057.
COASTAL FLOOD ADVISORY UNTIL 7 AM EST THURSDAY FOR VAZ052>055-
057.
WIND ADVISORY FROM 7 PM THIS EVENING TO 1 AM EST THURSDAY
FOR VAZ021.
WIND ADVISORY UNTIL 1 AM EST THURSDAY FOR VAZ025>031.
WV...HIGH WIND WARNING UNTIL 7 PM EST THIS EVENING FOR WVZ050-054-
055-501>504.
WIND ADVISORY FROM 7 PM THIS EVENING TO 1 AM EST THURSDAY FOR
WVZ050-054-055-501>504.
WIND ADVISORY UNTIL 1 AM EST THURSDAY FOR WVZ051>053.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM THURSDAY TO 7 AM EST FRIDAY
FOR ANZ530>543.
GALE WARNING UNTIL 6 AM EST THURSDAY FOR ANZ530>543.
&&
$$
UPDATE...RDH
PREVIOUS DISCUSSION...LISTEMAA/SBK
