FXUS61 KLWX 101957
AFDLWX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
257 PM EST THU DEC 10 2009

.SYNOPSIS...
HIGH PRESSURE WILL BUILD EASTWARD OVER THE MID ATLANTIC 
OVERNIGHT...AND CONTINUE TO DOMINATE THE WEATHER PATTERN THROUGH 
FRIDAY. COLD AND DRY CONDITIONS WILL PREVAIL THROUGH THE FIRST PART 
OF THE WEEKEND. THE HIGH CENTER WILL MOVE OFFSHORE ON SATURDAY...AND 
A LOW PRESSURE SYSTEM WILL MOVE UP THE EASTERN SEABOARD SUNDAY
INTO EARLY NEXT WEEK. 

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
HIGH PRESSURE CENTERED OVER THE SOUTHERN PLAINS WILL CONTINUE TO 
BUILD EASTWARD INTO THE MIDDLE ATLANTIC OVERNIGHT AS STRONG LOW 
PRESSURE CONTINUES TO MOVE ACROSS QUEBEC. COLD AIR WILL BEGIN TO 
SETTLE ACROSS THE REGION TONIGHT. ALREADY...READINGS IN THE FAR 
WESTERN CWFA ARE BETWEEN 25 AND 30 DEGREES COLDER THAN THIS TIME 
YESTERDAY. ELSEWHERE...TEMPS ARE ABOUT 5 TO 10 DEGREES COLDER THAN 
THIS TIME YESTERDAY.

THE PRESSURE GRADIENT REMAINS TIGHT BETWEEN STRONG LOW PRESSURE 
ACROSS CANADA AND THE HIGH BUILDING EASTWARD. WINDS ARE 
GUSTY...MOSTLY AVERAGING BETWEEN 20 AND 30 MPH ACROSS MOST LOCALES. 
WINDS WILL REMAIN GUSTY OVERNIGHT...ESPECIALLY IN THE HIGHER TERRAIN 
OUT WEST.

THE MAIN STORY FOR OVERNIGHT WILL BE THE WIND CHILLS OUT WEST. HAVE 
HOISTED A WIND CHILL ADVISORY FOR THE WESTERN FIVE COUNTIES...AS THE 
GUSTY WINDS COMBINE WITH THE COLD AND DRY CONDITIONS. 

SNOW SHOWERS WILL TAPER OFF THIS EVENING ALONG THE WESTERN FACING 
RIDGES.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/...
HIGH PRESSURE CONTINUES THROUGH TOMORROW...WITH WINDS REMAINING 
GUSTY. GUST SHOULD AVERAGE BETWEEN 20 AND 30 MPH. MAX TEMPS WILL 
STRUGGLE TO GET OUT OF THE 20S OUT IN THE WESTERN TERRAIN...WHILE 
TEMPS ELSEWHERE WILL RANGE FROM THE LOWER 30S TO AROUND 40 ACROSS 
LOWER SOUTHERN MARYLAND. 

&&

.LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/...
HIPRES MOVES OVRHD FRI NGT INTO SAT MRNG. LOW TEMPS SAT MRNG WILL 
RANGE FROM THE MID TEENS ACROSS THE POTOMAC HIGHLANDS TO MID 20S IN 
THE URBAN AND COASTAL AREAS. TEMPS MODERATE TOWARDS NORMAL FOR THIS 
TIME OF YR ON SAT AS HIPRES MOVES OFFSHORE AND RETURN FLOW BECOMES 
SLY. 

WEAK UPPER SHORTWAVE TROUGH MOVES ACROSS THE GREAT PLAINS SAT BEFORE 
APPROACHING THE AREA SAT. MODELS CONTINUE TO SHOW SFC CYCLOGENESIS 
ALONG THE CAROLINA COAST ERY LATE SAT NIGHT/SUN. DEVELOPING 
ISENTROPIC LIFT WILL SUPPORT INCREASING CHANCES FOR PRECIP DURING 
THIS TIME. PRECIP TYPE FCST REMAINS A CHALLENGING ONE WITH WAA UNDER 
SLY FLOW AIDING TO WARM H8 TEMPS TO ABOVE FREEZING FROM SW TO NE 
SUN. HAVE ADDED THE POSSIBILITY OF A FEW HRS OF FREEZING RAIN W OF 
I-95 SUN MRNG WITH COLD AIR AT THE SFC HANGING ON A LITTLE
LONGER. ELSEWHERE...A RA/SN MIX POSSIBLE IN THE MRNG BEFORE
CHANGING TO ALL RAIN EVERYWHERE AS THE LOW LVLS CONT TO WARM.

ARCTIC AIRMASS WILL PUSH INTO THE C CONUS ERY NEXT WEEK. THE 
ASSOCIATED COLD FRONT MOVES THRU TUE WITH MUCH COLDER TEMPS 
EXPECTED FOR THE MIDDLE PART OF NEXT WEEK. AN UPSLOPE SNOW EVENT
APPEARS TO SETUP BEHIND THE FRONT.

&&

.AVIATION /20Z THURSDAY THROUGH TUESDAY/...
VFR CIGS/VSBYS WILL CONTINUE THROUGH TOMORROW. WIND DIRECTION WILL 
REMAIN OUT OF THE WEST. GUSTS TO 30 KT WILL CONTINUE THROUGH THE 
AFTERNOON. OVERNIGHT AND TOMORROW...GUSTS SHOULD AVERAGE BETWEEN 20 
AND 25 KT.

WINDS WILL RELAX FRI NGT AND SAT AS HIPRES SETTLES OVRHD. LOPRES 
WILL DEVELOP WILL MOVE UP THE ERN SEABOARD LATE THIS 
WEEKEND...BRINGING A CHANCE OF PRECIP LATE SAT NGT INTO SUN. PRECIP 
MAY START OUT AS A WINTRY MIX BEFORE CHANGING TO ALL RAIN BY SUN 
AFTN.

STRONG ARCTIC FRONT EXPECTED TO MOVE THRU TUE WITH GUSTY NW WINDS 
BEHIND THE FRONT FOR THE MIDDLE OF NEXT WEEK.

&&

.MARINE...
SOLID SMALL CRAFT CONDITIONS WILL CONTINUE ACROSS THE MARINE AREA 
TONIGHT AND TOMORROW. HAVE INCLUDED GUSTS TO 30 KT ON THE BAY 
OVERNIGHT...WITH 25 KT ON THE LOWER POTOMAC. GUSTS OF 25 TO 30 KT 
WILL CONTINUE TOMORROW. WIND DIRECTION WILL REMAIN WESTERLY.

HAVE EXTENDED SCA THRU FRI EVNG. WINDS SHOULD RELAX OVRNGT AND SAT 
AS HIPRES MOVES OVR THE WATER. SCA CONDITIONS EXPECTED IN WAKE OF AN 
ARCTIC COLD FRONT FOR THE MIDDLE PART OF NEXT WEEK.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...NONE.
MD...WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST 
     FRIDAY FOR MDZ501.
VA...WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST 
     FRIDAY FOR VAZ021.
WV...WIND CHILL ADVISORY FROM 10 PM THIS EVENING TO 10 AM EST 
     FRIDAY FOR WVZ054-501-503.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EST FRIDAY FOR ANZ530>543.

&&

$$
LISTEMAA/KLEIN