FXUS61 KRLX 250652
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
150 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 PM THIS EVENING/...
WIND ADVISORY IN MOUNTAIN COUNTIES HAS BEEN UPGRADED TO A HIGH WIND
WARNING. DESPITE STABILITY OF THE BOUNDARY LAYER...RIDGES AND
MOUNTAIN PASSES APPEAR LIKELY TO RECEIVE DAMAGING WIND GUSTS IN
EXCESS OF 60 MPH. KRLX RADAR ALREADY INDICATING 45-65 KNOT WINDS
ONLY 2 TO 3 KFT OFF THE GROUND. MODELS CONTINUE TO SHOW 850MB WINDS
INCREASING INTO THE 60-80 KNOT RANGE LATER THIS MORNING THROUGH
EARLY AFTERNOON. VALLEYS WITHIN THE BOUNDARY LAYER WILL NOT HAVE
WARNING CRITERIA GUSTS...BUT HIGHER TERRAIN ABOVE THE BOUNDARY LAYER
IN THE MORE MOUNTAINOUS ZONES OF WV AND VA WILL BE EXPOSED TO THE
HIGH WINDS.
THE ONGOING FREEZING RAIN ADVISORY FOR
RALEIGH-FAYETTE-RANDOLPH-POCAHONTAS WV STILL LOOKS QUITE
VALID...ESPECIALLY GREENBRIER VALLEY.
&&
.SHORT TERM /6 PM THIS EVENING 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 /07Z 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...HIGH WIND WARNING 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...HIGH WIND WARNING UNTIL 4 PM EST THIS AFTERNOON FOR VAZ003-004.
&&
$$
SYNOPSIS...KTB/JSH/ARJ
NEAR TERM...KTB/MDP
SHORT TERM...AAR
LONG TERM...JSH
AVIATION...MDP
