FXUS61 KAKQ 241518
AFDAKQ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE WAKEFIELD VA
1018 AM EST THU DEC 24 2009
.SYNOPSIS...
CANADIAN HIGH PRESSURE BUILDS SOUTH ACROSS THE AREA THIS AFTERNOON
AND TONIGHT. STRONG LOW PRESSURE MOVES NORTHEAST INTO THE GREAT
LAKES REGION ON CHRISTMAS DAY...LIFTING A WARM FRONT THROUGH THE
MID ATLANTIC STATES BY THE LATE MORNING HOURS. THE TRAILING COLD
FRONT WILL THEN CROSS THE REGION ON SATURDAY...WITH HIGH PRESSURE
BUILDING BACK IN FROM THE WEST SUNDAY INTO EARLY NEXT WEEK.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
LTST MSAS SHOWING 1030MB "BUBBLE HIGH" PARKED ON TOP OF FA ATTM.
CAA HAS SENT DP TMPS TUMBLING INTO THE TEENS MOST AREAS XCPT
REMAINING IN THE 20S ACROSS SERN VA/NE NC. MEANWHILE...LTST SFC
OBS / VSBY SAT SHOW LITTLE OR NO CLOUD COVER ACROSS THE RGN. SO
WITH THE ABOVE IN MIND...MADE SOME CHANGES TO CRNT GRIDS. LWRD
CLOUD COVERAGE THIS AFTRN AS IT WILL AKE MOST OF THE AFTRN FOR ANY
CLOUDS TO SPILL E OF RIDGE AXIS (SUNNY TO M SUNNY). ALSO LWRD TMPS
BY 2-3 DEGREES MOST AREAS AS 12Z DATA SPRTS HIGHS IN THE U30S N TO
M40S S (NO HIGHER THAN 10 DEGREES FROM CRNT VALUES).
&&
.SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/...
AS UPR LEVEL RIDGE AXIS SLIDES EAST TWDS THE COAST OVERNIGHT...DEEPER
MSTR WILL SLOWLY WORK INTO THE REGION FROM THE WEST. OVERALL
THOUGH...MODEL SOLNS APPEAR TO BE A FEW HRS SLOWER WHICH MAKES
SENSE GIVEN THE DEEP AMPLIFICATION. THIS MAY ALSO LEAD TO COLDER
TEMPERATURES INITIALLY THU EVENG...BUT NOT BETTER CHANCES FOR ANY
SLEET OR FRZ RAIN SINCE THE MSTR WILL NOT BE THERE YET. TEMPS MAY
BOTTOM OUT EARLY...THEN STEADY FOR THE LATE EVENG/OVERNGT PERIOD
(LIKELY RISING A BIT OVER THE SE VA/NE NC ZONES).
HAVE SCALED BACK ON ANY POPS TIL AFTER 09Z...WITH ONLY A 20-30%
CHC FOR THE PIEDMNT FROM 09-12Z. BOTH GFS AND NAM BUFR SNDGS SHOW
ANY COLD AIR TO BE VERY SHALLOW (1000-850 MB THICKNESSES WOULD
SUGGEST ONLY -RA). STILL...GIVEN THE CLIMATOLOGY AND THE EXISTING
SNOWPACK...HAVE LEFT IN A BRIEF PERIOD OF MAINLY FZRA THROUGH 14Z
FOR AREAS FROM FVX TO LKU (WITH A CHC OF FZRA TO GOOCHLAND/WRN
HANOVER/POWHATAN, ETC). NO WATCHES WILL BE ISSUED AS QPF DURING
THIS TIMEFRAME WILL BE VERY LIGHT...PROBABLY ON THE ORDER OF A FEW
HUNDREDTHS AT MOST (AND TOO EARLY FOR AN ADVSY SINCE CURRENT TRENDS
SUGGEST BY THERE MAY NOT BE ANY PRECIP UNTIL TEMPS RISE ABOVE
32F).
THE MAIN EVENT WILL BE RAIN...OVERSPREADING THE REGION FROM W TO E
THROUGH CHRISTMAS DAY (LOWERED MRNG/ERLY AFTN POPS IN THE EAST AS
THESE AREAS LOOK TO KEEP A LOT OF DRY AIR IN PLACE THROUGH MOST OF
THE COLUMN UNTIL LATE IN THE DAY).
TEMPS WILL DISPLAY THE CAD TYPE OF PATTERN...HIGHS STRUGGLING TO
REACH THE LWR 40S IVOF LKU BUT UPR 50S TO LWR 60S NE NC.
SECONDARY LOW DEVELOPS THEN MOVES N ALONG THE OCCLUDED FRONT FRI NITE/ERLY
SAT MORN. THIS KEEPS CAT PCPN CHCS GOING DURING THE EVENING...AND
AT LEAST SCTD SHWRS AFTER MIDNIGHT. ISLTD THUNDER PSBL TO THE S&E
OF WHERE TRIPLE PT TRACKS...WHICH APPEARS TO BE ALONG THE OUTER
BANKS ATTM...SO WILL CONT TO LEAVE THUNDER OUT OF FCST WITH THIS
PACKAGE. LOWS FROM THE UPR 30S/LWR 40S NW TO MID 50S SE. QPF
WISE...AVG RAINFALL BTWN 1/2 TO 1 INCH XPCTD (LCLLY HIGHER AMTS OF
1 TO 1.5 INCHES PSBL ACROSS THE PIEDMONT AND ALONG THE COAST IF
ANY CONVECTION DOES DVLP). THIS RAIN COMBINED WITH ANY SNOWMELT
CUD CERTAINLY LEAD TO MINOR FLOODING PTNTL COME FRI AFTRN/NIGHT.
TO EARLY FOR A WATCH ATTM...BUT WILL HIGHLIGHT IN HWO.
FRONT PUSHES E OF RGN SAT AM TAKING THE PCPN WITH IT. KEPT POPS SAT
AM FOR THE CNTRL AND EAST...BUT DROPPED POPS BY LATE MRNG/AFTN AS
DEEPER SW FLOW KICKS IN. KEEPING SKIES PTLY SUNNY IN THE AFTN EVEN
THOUGH MODEL SNDGS SHOW A SHALLOW LAYER OF LOW LVL MSTR. MILD
WITH HIGHS ARND 50 NW TO THE LWR 60S SE.
&&
.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
NO REAL BIG FORECAST ISSUES FOR THIS PERIOD AS CAA SHOULD BE WELL
UNDERWAY BEHIND AFOREMENTIONED SYSTEM. ECMWF DOES HINT AT SOME
MOISTURE TRYING TO FILTER IN ON MONDAY. NOT ENOUGH EVIDENCE TO
SUPPORT THAT SO WL LEAVE DRY IN DAYS 5 THROUGH 7 FOR RIGHT NOW. JUST
LOOK TO HAVE BELOW NORMAL TEMPS FOR THE ENTIRE LATTER PERIODS AND
DRY...OTHER THAN A FEW CLOUDS/FLURRIES POSSIBLE MONDAY INTO TUESDAY
WITH VORT SWINGING ACRS THE AREA.
&&
.AVIATION /15Z THURSDAY THROUGH MONDAY/...
HI PRES RDGING DOWN INTO THE REGION FM THE N WILL MAINTAIN GENERALLY
VFR CONDITIONS ACRS THE AREA THRU TDY. MAINLY JUST SOME HI CLDS
INCRSNG FM THE WSW...ESPLY THIS AFTN. CLDS WILL THICKEN AND CIGS
WILL LWR LATER TNGT INTO FRI MORNG...AS A WARM FRNT APPROACHES FM
THE S. RAIN WILL MOVE ACRS THE AREA FM W TO E FRI MORNG INTO ERLY
SAT MORNG...WITH IFR CIGS AND VSBYS LIKELY AT ALL TAF SITES. COLD
FRONT PUSHES THRU SAT WITH DRY WX AND MAINLY VFR CONDITIONS
RETURNING FOR SAT NGT THRU MON.
&&
.MARINE...
WILL HAVE SCA HEADLINE FOR ALL WTRS STARTING FRI MORNG AND
CONTINUING THRU LATE FRI NGT...AS STRNG E OR SE WNDS AFFECT THE
REGION IN ADVANCE OF A WRM FRNT. COLD FRNT THEN PUSHES ACRS THE WTRS
THEN OFF THE CST SAT INTO SAT EVENG. STRNGER W WNDS THEN AFFECT THE
AREA SUN NGT AND MON.
&&
.CLIMATE...
STILL A DECENT CHANCE FOR AN "OFFICIAL" WHITE CHRISTMAS AT
RICHMOND (A SNOW DEPTH OF 1" OR MORE ON THE GROUND MEASURED AT 12Z
ON CHRISTMAS MORNING). CURRENT DEPTH REPORTED AT RIC IS 3"...WITH
JUST ONE DAY TO GO...AND FAIRLY COLD TEMPERATURES CONTINUING.
RECORDS HAVE BEEN KEPT AT RICHMOND SINCE 1897...MAKING FOR A 113
YEAR PERIOD INCLUDING THIS YEAR. OF THESE 113 CHRISTMAS'...ONLY 8
HAVE HAD 1" OR MORE ON THE GROUND (A 7% CHANCE)...AND LAST
OCCURRENCE OF 1" OR MORE ON THE GROUND WAS BACK IN 1966. (NOTE: A
FEW MORE RECENT YEARS...1993/1981/1970/1969 HAD SNOWFALL OCCUR
DURING THE DAY BUT W/ A 12Z MEASURED DEPTH OF ZERO).
&&
.EQUIPMENT...
PHONE SERVICE AT AKQ CONTS TO BE SPORATIC AT BEST. ALL NOAA
HAZARDS/WEATHER RADIO TRANSMITTERS OPERATING OUT OF AKQ ARE
DOWN AGAIN. RETURN TO SERVICE TIME UNKNOWN. PNS HAS BEEN ISSUED.
&&
.AKQ WATCHES/WARNINGS/ADVISORIES...
MD...NONE.
NC...NONE.
VA...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 10 AM FRIDAY TO 6 AM EST SATURDAY
FOR ANZ630>633-650-652-654-656-658.
&&
$$
SYNOPSIS...MPR
NEAR TERM...MPR
SHORT TERM...LKB
LONG TERM...KLL
AVIATION...TMG
MARINE...TMG
CLIMATE...LKB
EQUIPMENT...AKQ
