FXUS61 KRLX 220537
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
1235 AM EST TUE DEC 22 2009
.SYNOPSIS...
SOME SNOW SHOWERS OR FLURRIES WITH WEAK UPPER AIR DISTURBANCES
THROUGH TUESDAY. HIGH PRESSURE FOLLOWS. NEXT LOW PRESSURE SYSTEM
COMES LATE IN THE WEEK INCLUDING THE HOLIDAY.
&&
.NEAR TERM /THROUGH TODAY/...
OTHER THEN UPSLOPE FORCING IN MOUNTAINS INTO TONIGHT THE SHOWERS
WILL BE ENDING. SOME ISENTROPIC LIFT SLIDING IN FROM WEST IN
NORTHERN HALF TO TWO THIRDS OF FORECAST AREA TUESDAY. THIS MAY KICK
OFF SOME LIGHT SNOW BUT IT MAY NOT EVEN BE ABLE TO REACH GROUND. AS
A RESULT HAVE KEPT POPS BELOW SLIGHT CHANCE PUT PUT FLURRIES IN THE
WEATHER GRIDS FOR TUESDAY. HAVE GONE BELOW THE MOS MAX TEMPS FOR
TUESDAY WITH CLOUDS AND SNOW ON THE GROUND.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...
WEAK SHORTWAVE PASSES BY WITH LITTLE FORCING OF NOTE AND EXITS BY
TUESDAY NIGHT. SOME RESIDUAL MOISTURE WILL REMAIN..ESPECIALLY ALONG
THE MOUNTAINS. KEPT CONSIDERABLE CLOUDS IN PLACE...BUT POPS WERE
KEPT LOW.
MID LEVEL PATTERN AMPLIFIES WEDNESDAY...WITH DEEP TROUGH CARVING OUT
THE SOUTHWESTERN US. RIDGING FOR THE EAST. THIS OPENS THE DOOR FOR
DECENT WAA INTO THE MID ATLANTIC STATES AS NEXT SYSTEM GETS
ORGANIZED OVER THE CENTRAL UNITED STATES BY THURSDAY.
A WARM FRONT PUSHES NORTH THURSDAY WITH ISENTROPIC LIFT AND OVER-
RUNNING MOISTURE BY THURSDAY. ALTHOUGH THERE ARE SCANT AMOUNTS OF
QPF BEING PRODUCED BY THE MODELS...HAVE STARTED AN UPSWING IN POP
VALUES THROUGH THE DAY THURSDAY AS THE ATMOSPHERIC COLUMN
MOISTENS. MODELS ARE COMING IN LINE WITH TIMING AND PLACEMENT OF
STORM SYSTEM...SLOWING THE EASTERN PROGRESSION MAIN BAROCLINIC
ZONE.
FOR TEMPS...FIGURE SNOW PACK WILL KEEP VALUES BELOW GUIDANCE...
ESPECIALLY DURING THE NIGHT TIME HOURS. PRETTY MUCH TOOK A BLEND OF
ADJMAVBC AND SREFBC NUMBERS AND NUDGED THEM TO THE COOLER END OF THE
GUIDANCE SPECTRUM. WITH STRONGER WAA OCCURRING ON THURSDAY...MADE A
MORE SUBTLE CHANGE TO THE GUIDANCE NUMBERS. IN THE END...THE TEMPS
SEEMED TO MATCH UP QUITE WILL WITH THE PREVIOUS FORECAST PACKAGE.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
MODELS CONTINUE TO INDICATE PRECIPITATION WILL OVERSPREAD THE REGION
CHRISTMAS EVE. WARM TEMPS ALOFT AND SUB-FREEZING SFC TEMPS SUGGEST
THE CHANCE OF SIGNIFICANT ICING ACROSS PORTIONS OF THE NORTHERN AND
CENTRAL MOUNTAINS COUNTIES. ACROSS THE REMAINDER OF THE AREA...THE
PRECIPITATION SHOULD FALL IN THE FORM OF RAIN.
IT APPEARS CHRISTMAS WILL ALSO BE A WET DAY. HOWEVER...
TEMPERATURES WILL WARM ABOVE FREEZING EVERYWHERE...ALLOWING THE
PRECIPITATION TO BE ALL RAIN.
COULD ALSO BE QUITE BREEZY CHRISTMAS EVE INTO EARLY CHRISTMAS AS
GFS/ECMWF BOTH CONTINUE TO SUGGEST 850 MB WINDS IN EXCESS OF 50
KT. THESE GUSTY WINDS WOULD MOST LIKELY BE FELT ACROSS THE
HIGHEST ELEVATIONS.
FRIDAY NIGHT IS BEGINNING TO LOOK LIKE A MESSY NIGHT AS LATEST
MODELS DO NOT BRING IN THE COLD AIR ALOFT UNTIL AFTER 00Z IN THE
WEST AND 06Z IN THE EAST. WITH THIS IN MIND...APPEARS PRECIPITATION
IN THE MOUNTAINS COULD BE A WINTRY MIX OF RAIN...TO FREEZING
RAIN/SLEET TO SNOW WITH THE PRECIPITATION. ACROSS THE LOWLANDS...
THE PRECIPITATION SHOULD GENERALLY CHANGING TO A MIX OF RAIN/SNOW
AND THEN ALL SNOW. HAVE GONE WITH A NON-DIURNAL TEMP CURVE AS
TEMPS SHOULD NOT FALL ACROSS THE HIGHER ELEVATIONS UNTIL LATER.
THE REGION SHOULD THEN REMAIN UNDER THE INFLUENCE OF AN UPPER LEVEL
LOW...WITH CONTINUED CHANCES OF SNOW SHOWERS THRU THE WEEKEND.
SURFACE HIGH PRESSURE THEN BUILD IN LATE IN THE PERIOD...SHUTTING
OFF ANY PRECIP CHANCES.
GENERALLY USED HPC TEMP GUIDANCE...WITH SOME TWEAKS TO REFLECT
LATEST ENSEMBLE GUIDANCE.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
LAMP AND SREF PROBABILITIES...AS WELL AS ATMOSPHERIC SOUNDINGS IN
THE MODELS...SUGGEST A MORE PESSIMISTIC FORECAST...MUCH OF IT DUE TO
EXTRA BOUNDARY LAYER MOISTURE FROM SLOWLY MELTING SNOW. MOST OF THE
AREA WILL EXPERIENCE IFR /EVEN LIFR IN SPOTS/ CIGS THROUGH ABOUT
14Z...ALONG WITH MVFR TO IFR VIS. A BAND OF FLURRIES MAY IMPACT THE
CENTRAL TO NORTHERN PART OF THE REGION MIDDAY THROUGH
AFTERNOON...ALONG WITH CIGS STAYING IN MVFR CATEGORY FOR MOST
LOCATIONS. CONTINUED MOIST BOUNDARY LAYER LEADS TO RETURN OF AT
LEAST MVFR CONDITIONS AREAWIDE LATE THIS EVENING.
AFTER 06Z WEDNESDAY...
POCKETS OF IFR CIGS OR VIS EXPECTED EARLY WEDNESDAY MORNING...FROM
MOIST BOUNDARY LAYER.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...AAR
NEAR TERM...AAR
SHORT TERM...KMC
LONG TERM...JSH
AVIATION...MDP
