000
FXUS61 KRLX 280014
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
714 PM EST MON DEC 27 2010
.SYNOPSIS...
STRONG...COLD NORTHWEST FLOW CONTINUES THROUGH TONIGHT AS MAJOR
UPPER LEVEL LOW MOVES OFF THE NEW ENGLAND COAST. WARMING TREND THIS
WEEK. STRONG COLD FRONT THIS WEEKEND.
&&
.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
BASED ON LATEST RADAR TRENDS AS WELL AS SURFACE OBSERVATIONS...WINTER
WEATHER ADVISORY...THAT WAS IN EFFECT UNTIL 9 PM...WAS CANCELLED.
REMAINDER OF DISCUSSION...
MAJOR LOW PRESSURE SYSTEM LOSING ITS GRIP OVER WV WEATHER AS IT
EXITS OFF THE NEW ENGLAND COAST. SNOW SHOWERS HAVE ENDED ACROSS
THE LOWLANDS. HOWEVER...UPSLOPE SNOW WILL CONTINUE OVER THE
NORTHEAST MOUNTAINS THIS EVENING...ENDING BY EARLY TUESDAY
MORNING.
THEN...A HIGH PRESSURE BUILDS ACROSS THE SOUTHERN PLAINS TUESDAY
THROUGH MID WEEK PROVIDING DRIER AND WARMER WEATHER CONDITIONS.
GUSTY WIND AND COLD/DRY TEMPERATURES WILL KEEP WIND CHILLS IN THE
NEGATIVE SIDE ACROSS MOST PARTS OF POCAHONTAS AND RANDOLPH COUNTIES
OVERNIGHT...BUT NOT REACHING THE COUNTY AVERAGE MINUS 10 ADVISORY
CRITERIA.
MODEL SOUNDINGS ALSO INDICATE THERE COULD BE BREAKS IN THE CLOUDS
LATER TODAY AND TONIGHT...MAINLY NEAR AND W OF THE OHIO RIVER. THIS
COULD PROVIDE COLDER TEMPS THERE.
WENT WITH A BLEND BETWEEN THE BIAS CORRECTED RUC13 AND CONSAII
GUIDANCE...TWEAKING DOWN AT SOME SITES.
&&
.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
LAST OF THE UPSLOPE SNOW SHOWERS WILL BE ENDING IN THE NORTHERN
MOUNTAINS TUESDAY MORNING AS MOISTURE BECOMES SHALLOW AND SURFACE
RIDGING TAKES OVER. EXPECT LOWER CLOUDS TO BREAK UP AS INVERSION
ALOFT IS TAKEN OUT. COULD BE A DECENT AMOUNT OF SUNSHINE BY THE END
OF THE DAY WEST OF THE MOUNTAINS.
MINOR RIPPLE IN THE MIDLEVEL FLOW MOVES THROUGH TUESDAY
NIGHT...ALONG WITH ANOTHER THIN BAND OF MOISTURE. NOT ENOUGH FOR A
15-PLUS POP ANYWHERE...BUT NOT SURE THE MOUNTAINS STAY UNSCATHED AS
THIS MOVES BY. WITH THE SOUNDINGS ALL BELOW 0C BUT THE MOIST LAYER
WARMER THAN -10C...CONCERNED THAT THERE COULD BE A MINOR PERIOD OF
FREEZING DRIZZLE. LIMITED THIS TO THE HIGHER ELEVATIONS...AND DO
NOT THINK IT WILL BE A BIG ISSUE.
BY 12Z WEDNESDAY...HIGH PRESSURE WILL BE CENTERED OVER CWA...WITH
SOME OF THE MILDEST TEMPERATURES SEEN IN OVER 2 WEEKS. WITH
SOUTHWEST FLOW DEVELOPING LATE IN THE DAY...SHOULD START TO SEE SOME
MID/HI CLOUDS DEVELOPING DURING THE AFTERNOON.
GFS IS THE QUICKEST TO BRING IN QPF ASSOCIATED WITH WARM ADVECTION
ON WEDNESDAY NIGHT. THINK IT IS TOO QUICK CONSIDERING THE DRY
AIRMASS THAT WILL BE IN PLACE...ALONG WITH GENERAL LACK OF LIFT...SO
THINK NAM/ECMWF HAVE A BETTER IDEA HOLDING BACK PRECIPITATION.
BACKED OFF ON POP GRIDS A BIT...KEEPING CHANCE CONFINED TO THE FAR
SOUTHWEST THROUGH 12Z THURSDAY. WARMING ALOFT AT H850/H925 MAY
COUPLE WITH SURFACE TEMPERATURES AROUND 30 TO SET UP A PERIOD OF
LIGHT FREEZING RAIN LATE WEDNESDAY NIGHT AND THURSDAY MORNING. ANY
SUCH PRECIPITATION WILL BE LIGHT. BY 15Z...ALL PRECIPITATION WILL BE
RAIN WITH THE BOUNDARY LAYER WARMING SUFFICIENTLY. BEST OF THE WEAK
ISENTROPIC LIFT OCCURS OVER THE WESTERN COUNTIES...AND HAVE HIGHER
CHANCE POPS HERE ON THURSDAY.
TEMPERATURE GRIDS DO NOT STRAY TOO FAR FROM MOS GUIDANCE OVERALL.
&&
.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
WARMING TREND WILL CONTINUE THROUGH THE END OF THE WEEK AHEAD OF A
STRONG PACIFIC FRONTAL SYSTEM. WILL SEE THICKNESSES IMPROVE OVER
550DKM IN EXTENSIVE WARM AIR ADVECTION WITH SOUTHERLY FLOW. MAIN
AREA OF LOW PRESSURE WILL TRACK FROM THE LEE SIDE OF THE ROCKIES
NORTHEASTWARD INTO NORTHERN ONTARIO/HUDSON BAY FOR THE WEEKEND.
SYSTEM WILL HAVE ENOUGH DYNAMICS TO PLOW THROUGH THE CWA FAIRLY
EASILY DESPITE THE ROUTE OF THE LOW GENERALLY AWAY FROM THE CWA.
AT THIS POINT...TOO EARLY TO SPECULATE ON THE CHANCES FOR
THUNDER...ALTHOUGH RIGHT NOW IT LOOKS LIKE SUFFICIENT INSTABILITY
WILL NOT BE ACHIEVED. MAIN CONCERNS WILL BE RAINFALL
AMOUNTS...WIND...AND DEGREE OF MELTING OF THE SNOWPACK AFTER A
RATHER SNOWY DECEMBER. AS EXPECTED...MODELS SHOWING STRONG LOW LEVEL
JET WITH THIS SYSTEM...BUT MAY NOT TRANSLATE INTO SURFACE WINDS VERY
WELL DUE TO THE UPGLIDING NATURE PRIOR TO COLD FRONT PASSAGE. BETTER
MIXING DOWN TO THE SURFACE LIKELY ON THE BACK SIDE.
AS MENTIONED EARLIER...WILL CAREFULLY WATCH THE WIND SPEEDS AND
DEWPOINT RISES IN THE WARM SECTOR WHICH COULD EXACERBATE MELTING OF
THE SNOW PACK. PRECIPITABLE WATER AND FLASH FLOOD GUIDANCE VALUES
WILL ALSO BE CRUCIAL TO THE IMPACTS...IF ANY...WITH THIS SYSTEM THIS
WEEKEND.
&&
.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
SNOW SHOWERS WILL CONTINUE TO DIMINISH ACROSS THE MOUNTAINS THIS
EVENING. EXPECT VFR/MVFR CONDITIONS WILL PREVAIL ACROSS MUCH OF
THE AREA...WITH IFR CONDITIONS POSSIBLE ACROSS THE MOUNTAINS THIS
TONIGHT.
AFT 15Z...EXPECT VFR CONDITIONS SHOULD BE COMMON ACROSS ALL BUT
THE NORTHERN MOUNTAINS...WHERE MVFR CONDITIONS SHOULD CONTINUE. VFR
CONDITIONS ARE ANTICIPATED REGION-WIDE AFT 18Z.
FORECAST CONFIDENCE AND ALTERNATE SCENARIOS THROUGH 00Z WEDNESDAY...
FORECAST CONFIDENCE: MEDIUM.
ALTERNATE SCENARIOS: UPSLOPE SNOW SHOWERS COULD CONTINUE LONGER
THAN FORECAST...WHICH COULD AFFECT CIGS AND VSBY FCST
SIGNIFICANTLY.
EXPERIMENTAL TABLE OF FLIGHT CATEGORY OBJECTIVELY SHOWS CONSISTENCY
OF WFO FORECAST TO AVAILABLE MODEL INFORMATION:
H = HIGH: TAF CONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
M = MEDIUM: TAF HAS VARYING LEVEL OF CONSISTENCY WITH MODELS.
L = LOW: TAF INCONSISTENT WITH ALL MODELS OR ALL BUT ONE MODEL.
DATE TUE
UTC 1HRLY 00 01 02 03 04 05 06 07 08 09 10 11
EST 1HRLY 19 20 21 22 23 00 01 02 03 04 05 06
CRW CONSISTENCY M M H M M M M M L L M M
HTS CONSISTENCY H H M M H H L L L L M M
BKW CONSISTENCY L L L L L L L L L L M M
EKN CONSISTENCY M M M M M M M M M M M M
PKB CONSISTENCY H H H H M M M L L L M M
CKB CONSISTENCY L L L L L L M M M M M M
AFTER 00Z WEDNESDAY...
WIDESPREAD IFR CONDITIONS ARE NOT EXPECTED.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...26/CL/ARJ
NEAR TERM...JSH/ARJ
SHORT TERM...CL
LONG TERM...26
AVIATION...JSH
