FXUS61 KRLX 250544
AFDRLX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1244 AM EST FRI DEC 25 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 /UNTIL 6 AM THIS MORNING/...
UPDATE...TWEAKED THE POPS FOR THE INCOMING RAIN. DIFFICULT TO
JUDGE DUE TO THE DRY MID AND LOW LEVELS. WATCHING BKW TEMPERATURE
CAREFULLY AS IT SLOWLY DROPS...AND THINKING -FZRA IS STILL A
POSSIBILITY AS EVAPORATIVE COOLING TAKES HOLD WITH RAIN MOVING IN.

PREVIOUS DISCUSSION...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 /6 AM THIS MORNING 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 /06Z FRIDAY THROUGH TUESDAY/...
OCCLUDED FRONT SET TO PASS THROUGH THE AREA DURING ROUGHLY 10Z-
20Z...ACCOMPANIED BY MVFR CIGS AND PERHAPS VIS FROM RAIN.
HOWEVER...BIGGER IMPACT OF THIS SYSTEM IS DEGREE OF WIND
SHEAR FROM STRONG LOW LEVEL JET NOT FAR OFF THE GROUND...OUT OF
THE SOUTH-SOUTHEAST. FOR THE MOUNTAIN TERMINALS...CLOSE ENOUGH TO
THE GROUND TO INCLUDE WITHIN THE TAFS. ALSO...ALONG AND EAST OF
THE MOUNTAINS...INCLUDING KBKW AND GREENBRIER
VALLEY...TEMPERATURES COLD ENOUGH FOR FREEZING RAIN AT ONSET OF
RAIN...BEFORE CHANGING TO PLAIN RAIN LATER IN THE MORNING. SAME
LOCATION WILL HAVE MOISTURE RIDE UP THE TERRAIN TO PRODUCE
POTENTIAL IFR CIGS AS MAIN FRONTAL BAND APPROACHES AND THEN MOVES
THROUGH. MOST SITES RETURN TO VFR FOR A TIME BEHIND THE FRONT THIS
AFTERNOON...ONLY TO SINK BACK INTO MVFR CIGS /IFR POSSIBLE IN
MOUNTAINS/ TONIGHT.

AFTER 06Z SATURDAY...
IFR POSSIBLE IN LIGHT SNOW SUNDAY NIGHT.

&&

.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR WVZ033>038-046-
     047.
     FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR WVZ035-036-046-
     047.
OH...NONE.
KY...NONE.
VA...WIND ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR VAZ003-004.

&&

$$
SYNOPSIS...KTB/JSH/ARJ
NEAR TERM...KTB
SHORT TERM...AAR
LONG TERM...JSH
AVIATION...MDP