FXUS61 KLWX 110324
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1024 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 SOUTH CENTRAL CONUS WILL CONTINUE TO
BUILD EASTWARD TOWARD THE MIDDLE ATLANTIC REST OF TONIGHT AS STRONG
LOW PRESSURE MOVES ACROSS THE CANADIAN MARITIMES. COLDEST AIR
SINCE THIS PAST MARCH IS BUILDING IN ACROSS THE REGION.
OUT WEST...TEMPERATURES RANGE IN THE TEENS AT ELEVATION TO L/M 20S
IN THE VALLEYS. SINGLE DIGIT DEWPOINTS ACROSS THE AREA.
THE PRESSURE GRADIENT REMAINS TIGHT BETWEEN STRONG LOW PRESSURE
ACROSS ERN CANADA AND THE HIGH BUILDING EASTWARD. WINDS ARE
GUSTY...25 TO 30 MPH STILL POSSIBLE REST OF THE NIGHT ACROSS THE
AREA /WITH CAA MIXING DOWN GUSTS/...35 TO 40 MPH FOR HIGHER
TERRAIN INCLUDING THE BLUE RIDGE MTNS/CATOCTIN MTN.
CONTINUED THE WIND CHILL ADVISORY FOR THE WESTERN FIVE ZONES...AS
THE GUSTY WINDS COMBINE WITH THE COLD AND DRY CONDITIONS TO
PRODUCE WIND CHILLS -5 TO -10 OUT THERE. OTHER RIDGETOPS COULD SEE
WIND CHILLS DIP BELOW ZERO...THOUGH EXPANSION OF THE ADVISORY IS
NOT EXPECTED ATTM.
PRECIP HAS ENDED OUT WEST AND WAVE CLOUDS OFF ALLEGHENY FRONT
SHOULD CONTINUE TO DECLINE IN COVERAGE REST OF THE NIGHT...AIDING
RADIATIVE COOLING.
&&
.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 /03Z FRIDAY THROUGH TUESDAY/...
VFR CIGS/VSBYS WILL CONTINUE THROUGH TOMORROW. WIND DIRECTION WILL
REMAIN OUT OF THE WEST. GUSTS TO 25 KT WILL CONTINUE THROUGH THE
REST OF THE NIGHT...25 TO 30 KT FOR KMRB AND VALLEYS WEST OF THE
BLUE RIDGE MTNS. TOMORROW...WLY GUSTS SHOULD AVERAGE BETWEEN 20
AND 25 KT WITH 30 KT POSSIBLE ACROSS THE AREA LATE MORNING THROUGH
THE AFTERNOON.
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...
HIGH END SMALL CRAFT CONDITIONS CONTINUE REST OF TONIGHT AND TOMORROW ACROSS
THE MARINE AREA. CONTINUED IDEA OF WINDS 25 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 UNTIL 10 AM EST FRIDAY FOR MDZ501.
VA...WIND CHILL ADVISORY UNTIL 10 AM EST FRIDAY FOR VAZ021.
WV...WIND CHILL ADVISORY UNTIL 10 AM EST FRIDAY FOR WVZ054-501-503.
MARINE...SMALL CRAFT ADVISORY UNTIL 11 PM EST FRIDAY FOR ANZ530>543.
&&
$$
UPDATE...BAJ
PREV DISC...NWL/JRK
