FXUS61 KLWX 261524
AFDLWX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
1024 AM EST THU NOV 26 2009
.SYNOPSIS...
LOW PRESSURE OFF THE SOUTH CAROLINA COAST MOVE UP THE EASTERN
SEABOARD TODAY. A COLD FRONT WILL MOVE THROUGH THE MID ATLANTIC
STATES TONIGHT. HIGH PRESSURE RETURNS FOR THE WEEKEND.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
VISIBILITIES HAVE IMPROVED WEST OF THE BLUE RIDGE OVER THE PAST
HOUR OR SO...AND VISIBLE IMAGERY EVEN INDICATES SOME CLEARING
SKIES. EAST OF THE BLUE RIDGE IS ENTIRE DIFFERENT...AS SATELLITE
SHOWS EXTENSIVE STRATUS DECK IN CONJUNCTION WITH LINGERING DENSE
FOG. DENSE FOG ADVISORY WAS CHOPPED OFF FOR WESTERN AREA...AND
KEPT TIL NOON FOR EASTERN AREAS. AM STARTING TO WONDER IF SOME
AREAS MAY REMAIN DENSE EVEN AFTER NOON. FORECAST TREND IS FOR
IMPROVING VISIBILITIES INTO EARLY AFTERNOON.
OUTSIDE OF THE FOG...WHICH HAS BEEN AS WIDESPREAD AND DENSE AS
HAS BEEN SEEN IN THIS NECK OF THE WOODS IN A WHILE...WILL WATCH
LOW PRESSURE OFF THE SOUTHEAST COAST START TO LIFT NORTH. LOW
SHOULD REMAIN FAR ENOUGH OFF THE COAST FOR OUR CWA TO NOT DIRECTLY
BE IMPACTED...BUT THERES A POTENT UPPER TROUGH UPSTREAM WHICH WILL
APPROACH THIS AFTERNOON...LIKELY CAUSING SHOWERS TO START TO BREAK
OUT LATER THIS AFTERNOON ACROSS THE HIGHLANDS. THESE WILL
TRANSLATE EAST ACROSS THE AREA OVERNIGHT...AND COLDER
TEMPERATURES WILL CHANGE RAIN SHOWERS TO SNOW SHOWERS ACROSS THE
HIGHLANDS. WILL ADDRESS THAT MORE IN THE AFTERNOON PACKAGE.
FOR TEMPERATURES TODAY...HAVE LOWERED THEM ESPECIALLY EAST OF THE
MTNS GIVEN THE EXTENSIVE FOG/CLOUD COVER THAT MAY BE RECALCITRANT
INTO THE EARLY AFTERNOON.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/...
AT THE SFC THERE ARE 2 DISTINCT LOW PRES CENTERS - OVER THE GRT
LKS AND OFF THE SC CST. NATL RDR SHOWS RA OFF THE NC CST...AND
THIS PCPN WL RMN OFF THE CST TNGT. ACTUALLY WE'LL BE IN THE
SUBSIDENCE RGN FM THIS...WHICH IS THE REASON SKIES HV GONE CLR OVR
MUCH OF TEH FSCT AREA ATTM. GRK LK LOW AND ITS ATTENDANT FNT WL
THE WX CREATOR FOR US LATE TDA AND TNGT. BEST CHC FOR PCPN WL BE
AFTR MDNGT AS FNT CROSSES THE CWA. 850 TEMPS GO SUBFRZG IN THE
HIGHLANDS AFTR MDNGT AND RA WL LKLY MIX W/ CHG TO SNOW BY FRI
MRNG. WINT STORM WATCH HAS BEEN PUSHED BACK TO AFTR 06Z BECAUSE
TEMPS WL BE IN THE 40S DURG THE EVE HRS.
AND THOSE TWO LOW CENTERS LOOK TO COMBINE S OF NEW ENGLAND LATE
TNGT - INTENSIFYING THE PRES GRAD WHICH WL CAUSE THE WINDS TO PICK
UP IN THE ERN PART OF THE AREA.
LOWS RANGE FM A30 IN THE FARTHEST W TO L40S E.
&&
.LONG TERM /FRIDAY THROUGH WEDNESDAY/...
FAVORABLE SETUP FOR AN UPSLOPE SNOW EVENT ACROSS THE WRN SLOPES OF
THE POTOMAC AND ALLEGHENY FRONT WILL CONT FRI AND FRI NGT. CYCLONIC
FLOW AROUND THE UPPER LOW WILL SET UP A MOISTURE FETCH FROM THE
GREAT LAKES TO THE C APPALACHIANS. INVERSION HGTS WILL BE AROUND 4.5
KFT FRI WITH STEEP LAPSE RATES BELOW INVERSION. BEST MOISTURE FETCH
WILL BE ACROSS THE ALLEGHENY FRONT...WHERE A WINTER STORM WATCH
REMAINS IN EFFECT. THE POTENTIAL EXISTS FOR 5 INCH SNOW ACCUMS OVR A
24 HR PD. NONETHELESS...CONFIDENCE IS VERY HIGH FOR AT LEAST
ADVISORY LVL SNOWFALL ACROSS THIS AREA...AS WELL AS ACROSS THE RIDGE
TOPS IN WRN PENDLETON AND HIGHLAND COUNTIES.
WITH THE LOW BOMBING OUT JUST OFF THE NEW ENGLAND COAST...THE
PRESSURE GRADIENT WILL TIGHTEN BETWEEN THE LOW AND HIPRES OVER THE
GULF STATES. THE STRONG GRADIENT WILL RESULT IN A BRISK W-NW FLOW
FRI THRU SAT WITH WIDESPREAD GUSTS 20-30 MPH AND SLIGHTLY HIGHER
GUSTS TO 40 MPH ACROSS THE RIDGE TOPS OF THE APPALACHIANS. MAX TEMPS
WILL BE ABOUT 5-10F BELOW NORMAL FRI.
FOR THE WEEKEND...FLOW ABOVE BECOMES ZONAL WHILE HIPRES BUILDS IN AT
THE SFC. TEMPS WILL MODERATE A BIT TO NEAR NORMAL SAT AND SLIGHTLY
ABOVE NORMAL SUN.
NRN STREAM SHORTWAVE TROUGH PROGRESSES EWD AROUND THE UPPER LOW OVER
JAMES BAY LATE IN THE WEEKEND. THE SHORTWAVE ENERGY AND ATTENDANT
COLD FRONT WILL PUSH THRU THE AREA MON/MON NGT. HIPRES QUICKLY MOVES
OVRHD TUE BEFORE THE NEXT STORM SYSTEM APPROACHES MIDWEEK. THIS FAR
OUT...MODELS SIGNIFICANTLY DIFFER ON TIMING/EVOLUTION OF THIS SYSTEM.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
LIFR/IFR CONDITIONS WILL LINGER LONGEST AT THE HUBS...FORECAST TO
IMPROVE 17-18Z. LAMP WANTS TO HOLD ONTO LOW RESTRICTIONS
LONGER...BUT SURROUNDING OB SITES ARE STARTING TO SHOW IMPROVEMENT
SO WILL NOT BITE OFF ON THEM LINGERING AS LONG AS LAMP. SHOULD
HAVE IMPROVEMENT TO VFR LATE TODAY/EVENING...BUT A FRONT WILL
PROMOTE POSSIBLE MVFR SHOWERS OVERNIGHT.
VFR CONDITIONS EXPECTED FRI THRU ERY NEXT WEEK. A FEW SHOWERS ARE
POSSIBLE FRI DUE TO AN UPPER DISTURBANCE TRACKING OVER THE REGION.
MAIN WX-RELATED CONCERNS FOR AVIATION WILL BE THE GUSTY W-NW WINDS
BEHIND THE COLD FRONT. WIDESPREAD GUSTS TO 25 KT ARE EXPECTED FRI
AFTN THRU SAT. THE WINDS WILL RELAX LATER SAT AND SUN AS HIPRES
BUILDS ACROSS THE REGION.
&&
.MARINE...
WINDS WILL BE RELATIVELY TRANQUIL TODAY...BUT WILL INCREASE
OVERNIGHT AND ESPECIALLY FRIDAY BEHIND A FRONT.
SCA HEADLINE CONTINUES FOR FRI AND FRI NGT. A STRONG PRESSURE
GRADIENT WILL EXIST BETWEEN LOW PRESSURE RAPIDLY DEEPEN OFF THE NEW
ENGLAND COAST AND HIPRES BUILDING IN FROM THE SW. CONFIDENCE IS HIGH
OF ALL MARINE ZONES EXPERIENCING SOLID SCA CONDITIONS THRU THESE
PDS. SCA WILL LIKELY BE EXTENDED IN SAT. PERIODIC GUSTS TO 30 KT ARE
EXPECTED FRI AFTN THRU SAT ACROSS THE CHSPK BAY. THERE IS A CONCERN
FOR GALE WARNING CONDITIONS ACROSS THE CHSPK BAY FRI NGT BUT
CONFIDENCE IS NOT NEARLY HIGH ENOUGH TO ISSUE A 4TH PD GALE WARNING.
WINDS WILL RELAX DURING THE SECOND HALF OF THE WEEKEND AS THE LOW
DEPARTS AND HIPRES SETTLES ACROSS THE WATERS.
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR DCZ001.
MD...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR MDZ004>007-009>011-
013-014-016>018.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY NIGHT
FOR MDZ501.
VA...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR VAZ039>042-050>057.
WV...WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY NIGHT
FOR WVZ501-503.
MARINE...SMALL CRAFT ADVISORY FROM 2 AM FRIDAY TO 6 AM EST SATURDAY FOR
ANZ530>543.
&&
$$
PELOQUIN/WOODY!/JRK
