FXUS61 KLWX 261318 CCA
AFDLWX
AREA FORECAST DISCUSSION...COR TYPO
NATIONAL WEATHER SERVICE BALTIMORE MD/WASHINGTON DC
817 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/...
AM EXTENDING THE DENSE FOG ADVISORY UNTIL NOON. ALMOST ALL 8 AM
OBSERVATIONS WERE LESS THAN 1/4SM IN ONE OF THE MORE WIDESPREAD
DENSE FOG ADVISORY EVENTS IN AWHILE...AND FOG WILL BE SLOW TO
IMPROVE. LAMP KEEPS VSYBS OF 1/4SM OR LESS UNTIL 16-17Z EVEN. HARD
TO ARGUE WITH THAT...GIVEN THE STATE OF THE ATMOSPHERE. WILL CHISEL
AWAY AT THE DENSE FOG ADVISORY AS CONDITIONS IMPROVE LATE THIS
MORNING.
ORIGINAL MORNING DISCUSSION...
WE'VE GOT A FULL PLATE OF WX ON THIS THANKSGIVING MRNG -
FOG..WINDS..SNOW..A PD OF SUNSHINE. TIDES ARE STILL RUNNING SLTLY
ABV NRML...BUT THAT IS OF SUCH MINOR IMPORTANCE THAT I'VE REMOVED
IT FM THE DSCN.
ONE OF THE DENSEST..MOST XTNSV..FOG ADVISORIES IN MY MEMORY ATTM.
ERLR SHIFT DID AN XCLNT JOB OF RUNNING THE DENSE FOG ADVSRY FOR
THE ENTIRE OVRNGT PD. WE'VE ADDED THE FAR WRN TIER OF COUNTIES TO
THE ADSRY GIVEN 0-1/4 SM VBSYS. STLT SEEMS TO SHOW A LARGE AREA OF
CLR SKIES OVER THE WRN HALF OF THE CWA...BUT HERE..AND IN NMRS
OTHER LOCATIONS...FOG IS SO DENSE ATTM THAT VERT VSBY IS NIL.
AFTR ABT MID MRNG BLV THAT THE SUN WL MAKE AN APPEARANCE AND INTO
THE AFTN HRS. TEMPS WL RISE TO THE U50S OVR MUCH OF THE FCST AREA.
&&
.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 /13Z THURSDAY THROUGH MONDAY/...
AMENDED TAFS AS VLIFR CONDITIONS WILL LINGER LONGER THAN PREVIOUS
FORECAST. GRADUAL IMPROVEMENT OCCURS 16-17Z.
HERE AT IAD I CAN'T RECALL HEARING A TAKEOFF/LANDING ALL NGT. NOT
SURE IF THAT'S DUE TO WX OR THAT EVERYONE GOT WHERE THEY NEEDED TO
BE. MY GUESS IS THE FORMER. W/ XCPTN OF DCA BLV AIRPORTS HV SVRL
MORE HRS OF VLIFR B4 IMRVMNT BEGINS BY 10 AM. VFR THIS AFTN/EVE.
WINDS BEGIN TO INCRS B4 SUNRISE FRI.
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...
NO PROBS ON THE WATERS TDA. SCA WL GO INTO EFFECT OVRNGT FOR ALL
THE WATERS.
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 MDZ003>007-009>011-
013-014-016>018-501-502.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH LATE FRIDAY NIGHT
FOR MDZ501.
VA...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR VAZ021-025>031-
036>042-050>057.
WV...DENSE FOG ADVISORY UNTIL NOON EST TODAY FOR WVZ050>055-501>504.
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
