FXUS61 KRLX 242021
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
315 PM EST THU DEC 24 2009
.SYNOPSIS...
SANDWICHED BETWEEN LOW PRESSURE TO THE WEST AND HIGH PRESSURE TO THE
NORTHEAST. INCREASING WINDS OVERNIGHT AND CONTINUE ON CHRISTMAS
DAY. COLDER AIR GRADUALLY MOVES IN OVER THE WEEKEND.
&&
.NEAR TERM /THROUGH TONIGHT/...
EVEN THOUGH STORM TO OUR WEST NOT DEEPENING MUCH...THE GRADIENT
BETWEEN IT AND THE HIGH PRESSURE OVER NORTHERN ONTARIO AND QUEBEC
HAS SOME IMPRESSIVE WINDS IN THE LOW LEVELS ABOVE THE GROUND.
70 TO 80 KNOTS AT 850 MBS BY 09Z. WITH STABLE SOUNDINGS THINKING
MOST OF THESE MOMENTUM WILL STAY ALOFT...BUT STILL HAVE SOME 40 TO
50 KNOT WIND GUSTS OVER THE WIND ADVISORY AREA...OR OUR MOUNTAINOUS
TERRAIN.
HAVE THE WINDS INCREASING THIS EVENING...SO WIND ADVISORY STARTS AT
6 PM AND CONTINUES INTO CHRISTMAS DAY.
WITH THE STRONG UPSLOPE SE WINDS...I DO NOT UNDERSTAND WHY MOS
TEMPERATURE GUIDANCE IS SO MILD FOR PLACES LIKE BKW LATE TONIGHT.
I CAN SEE TEMPERATURES RISING IN THE WESTERN LOWLANDS. BUT WE WERE
HOLDING SOME POCKETS OF TEMPERATURES AT FREEZING THROUGH ABOUT 12Z
OR 13Z IN THE SOUTHERN WV MOUNTAIN COUNTIES...AND UNTIL LATE MORNING
IN EASTERN RANDOLPH AND POCAHONTAS COUNTY. SO THE FREEZING RAIN
ADVISORY IS FROM 1 AM TO NOON.
HAVE A NONDIURNAL TEMPERATURE TRACE OVERNIGHT...WITH READING
DROPPING THIS EVENING...THEN RISING OVERNIGHT...EXCEPT WHERE RAIN
BEGINS IN THE UPSLOPE AREAS.
&&
.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS THE STRONG LOW PRESSURE MOVE FROM THE CENTRAL PLAINS INTO THE
GREAT LAKES REGION...AN OCCLUDED FRONT WILL SWEEP ACROSS THE OH
VALLEY INTO WV ON FRIDAY. HAVE CATEGORICAL POPS SPREADING FROM
SOUTHWEST TO NORTHEAST FRI MORNING...AND EXITING MOST PARTS OF THE
NORTHEAST MOUNTAINS DURING THE LATE AFTERNOON EARLY EVENING HOURS.
A SECONDARY LOW PRESSURE DEVELOPS ACROSS THE SOUTHEASTERN STATES AND
MOVES ACROSS VA INTO SATURDAY...KEEPING LINGERING PCPN ACROSS THE
HIGHER ELEVATIONS OF THE NORTHEAST MOUNTAINS THROUGH EARLY SATURDAY.
MODELS ARE IN AGREEMENT OF A DRY SLOT PROVIDING DRIER AND COOLER
CONDITIONS FOR SATURDAY INTO EARLY SUNDAY. THEREFORE...KEPT THESE
PERIODS DRY UNTIL SUNDAY MORNING WHEN LIGHT SNOW FROM THE BACK OF
THE PARENT LOW PRESSURE FINALLY REACHES THE NORTHWEST SECTIONS...AS
THE LOW PULLS NORTHEAST INTO EASTERN CANADA.
FOR FRIDAY...SOME DIFFERENCES WERE NOTED IN H850 TEMPS AMONG MODELS
PERHAPS DUE TO SLIGHTLY TIMING DIFFERENCES OF THE ONSET OF REAL
COLD/DRY AIR ALOFT. HOWEVER...WITH A STRONG SOUTHEAST FLOW AT H850
NEAR 80 KNOTS PER THE NAM/GFS...70 KNOTS PER THE GEM/ECMWF...AND 50
KNOTS PER UKMET...FIGURED A GOOD DEAL OF WARM ADVECTION WILL TAKE
PLACE. THEREFORE...WENT ABOVE NORMAL TEMPS...AND WARMER THAN ALL
GUIDANCE ...BRINGING SFC TEMPS INTO THE LOWER 50S OR A BIT HIGHER
ACROSS THE LOWLANDS...AND INTO THE MID 40S HIGHER ELEVATIONS.
ABOVE NORMAL TEMPS WERE FIGURED FOR FRIDAY NIGHT...A DEGREE OR TWO
WARMER THAN THE GMOS. MAX TEMPS WILL LIKELY BE FORECAST EVEN HIGHER
AS WE GET CLOSER TO FRIDAY.
BEHIND THE BACK SIDE OF THE LOW...GFS/ECMWF H850 TEMPERATURES GETS
INTO THE MINUS 11C...WHILE THE UKMET BRINGS EVEN COLDER TEMPS INTO
THE MINUS MINUS 17 ALL UNDER NORTHWEST TO WEST FLOW. DESPITE THE
AFOREMENTIONED COLD ADVECTION...SOME CLEARING ARE EXPECTED ALONG THE
DRY SLOT PROVIDING SOME HEATING TO THE LOWLANDS ON SATURDAY.
..AND SOME RADIATIONAL COOLING ON SAT NIGHT BRINGING TEMPS INTO THE
MID 20S LOWLANDS....RANDING INTO THE MID TEENS NORTHEAST MOUNTAINS.
BELOW NORMAL TEMPS ARE EXPECTED AT MOST PLACES REMAINING AT OR BELOW
FREEZING FOR SUNDAY AND SUN NIGHT.
&&
.LONG TERM /MONDAY THROUGH THURSDAY/...
UPPER LEVEL LOW AND ASSOCIATED FORCING FOR PRECIPITATION WILL
PUSH EAST OF REGION MONDAY. HOWEVER....NORTHWEST UPSLOPE SNOW WILL
CONTINUE INTO TUESDAY...BEFORE HIGH PRESSURE BUILDS IN.
ANOTHER SYSTEM WILL THEN BEGIN TO APPROACH THE REGION...WITH
PRECIPITATION CHANCES BEGINNING WEDNESDAY...AND THEN CONTINUING
THROUGH THURSDAY.
MODELS SUGGEST AN SURFACE AREA OF LOW PRESSURE WILL MOVE FROM THE
NORTHERN GULF OF MEXICO INTO THE ATLANTIC OCEAN THURSDAY...WITH
THE STORM EXPECTED TO INTENSIFY AS IT MOVES UP THE EAST COAST NEW
YEARS DAY.
HPC TEMPERATURE GUIDANCE WAS GENERALLY USED...WITH SOME TWEAKS TO
REFLECT THE LATEST ENSEMBLE GUIDANCE.
&&
.AVIATION /19Z THURSDAY THROUGH TUESDAY/...
MAIN CONCERN THROUGH 18Z IS THE INCREASING SE LOW LEVEL WINDS.
WILL INCLUDE SOME LOW LEVEL WIND SHEAR WITH 35 TO 45 KNOTS AT ABOUT
2 THSD FT OFF THE GROUND...MAINLY AFTER 03Z.
CEILINGS AT 2 TO 4 THSD FT FORMING AFTER 06Z ALONG THE EASTERN SLOPES
INCLUDING BKW...THEN INTO THE WESTERN LOWLANDS BY 12Z FRIDAY. RAIN
OVERSPREADING FROM S TO N AFTER 06Z...WITH FREEZING RAIN POSSIBLE
FROM BKW TO EKN LINE AND E AT THE ONSET. POCKETS OF FREEZING RAIN
STILL ABOUT 15Z IN POCAHONTAS COUNTY.
RAIN EXITING FROM THE SW AFTER 15Z WITH CEILINGS LIFTING 3 TO 4 THSD
FT BKN VCNTY HTS.
AFTER 18Z FRIDAY...
LOW LEVEL WIND SHEAR STILL POSSIBLE AFTER 18Z FRIDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY FROM 6 PM THIS EVENING TO 4 PM EST FRIDAY FOR
WVZ033>038-046-047.
FREEZING RAIN ADVISORY FROM 1 AM TO NOON EST FRIDAY FOR WVZ035-
036-046-047.
OH...NONE.
KY...NONE.
VA...WIND ADVISORY FROM 6 PM THIS EVENING TO 4 PM EST FRIDAY FOR
VAZ003-004.
&&
$$
SYNOPSIS...KTB/JSH/ARJ
NEAR TERM...KTB
SHORT TERM...AAR
LONG TERM...JSH
AVIATION...KTB
