FXUS61 KRLX 110851
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
351 AM EST FRI DEC 11 2009
.SYNOPSIS...
HIGH PRESSURE BUILDS IN TO YIELD DRIER AND WARMER WEATHER THROUGH
SATURDAY. ANOTHER SYSTEM PASSES SOUTHWEST TO NORTHEAST SUNDAY
MORNING. COLD FRONT TUESDAY.
&&
.NEAR TERM /THROUGH TONIGHT/...
HIGH PRESSURE CURRENTLY CENTERED OVER WESTERN KY/TN WILL CONTINUE TO
BUILD WEST INTO THE REGION TODAY...CREATING DRY CONDITIONS. ALTHOUGH
THE SURFACE PRESSURE GRADIENT WILL CONTINUE TO SLACKEN ACROSS THE
REGION AS THE CENTER OF THE HIGH CONTINUES TO MOVE EAST...WINDS WILL
CONTINUE TO REMAIN GUSTY FOR MUCH OF TODAY AS LLJ REMAINS IN PLACE.
THE WINDS WILL BE GREATEST OVER SE OHIO AND NORTHERN MOUNTAIN ZONES
WHERE 850MB WIND SPEEDS OF AT LEAST 40KTS ARE EXPECTED...BEFORE
FINALLY MOVING OFF LATE FRIDAY NIGHT. HAVE INCREASED WINDS SLIGHTLY
ACROSS THE AFOREMENTIONED ZONES FRIDAY TO ACCOUNT FOR THIS...WITH AN
OVERALL DECREASE IN WINDS ACROSS THE CWA FRIDAY NIGHT.
OTHERWISE...EXPECTING A MOSTLY SUNNY AND WARMER FRIDAY...ALTHOUGH A
FEW HIGH CLOUDS ARE EXPECTED TODAY AS A WEAK SHORTWAVE MOVES THROUGH
THE REGION. HAVE INCREASED MAX TEMPS FOR TODAY SLIGHTLY FROM
YESTERDAYS FORECAST AS EXPECTING LESS CLOUD COVER...AND AS LOW LEVEL
TEMPS CONTINUE TO WARM. GENERALLY TRENDED MAX TEMPS CLOSER TO THE
MET.
TONIGHT WILL BE ANOTHER CHILLY NIGHT ACROSS THE FORECAST AREA...WITH
MOST LOCATIONS EXPERIENCING TEMPERATURES IN THE TEENS ONCE AGAIN.
THINKING MIN TEMPS SATURDAY MORNING WILL GENERALLY BE A FEW DEGREES
WARMER THAN FRIDAY MORNING AS CLOUD COVER AND WAA CONTINUES TO
INCREASE ACROSS THE REGION AHEAD OF AN APPROACHING STORM
SYSTEM...PROGGED TO MOVE INTO THE REGION SATURDAY NIGHT. ALTHOUGH
TEMPS WILL BE QUITE COLD AGAIN...WIND CHILL SHOULD NOT BE AN ISSUE
FRIDAY NIGHT/EARLY SATURDAY DUE TO DECREASED WINDS. ALTHOUGH
RANDOLPH AND POCAHONTAS COUNTIES WILL SEE WIND CHILLS DIP BELOW ZERO
AGAIN...NOT EXPECTED TO BE COLD ENOUGH TO WARRANT AN ADVISORY.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY/...
QUIET DAY ON SATURDAY. RETURN SW FLOW SETS UP AT H850 AS SURFACE
HIGH SLIDES OFF TO THE EAST. WARM ADVECTION-INDUCED CI/AC WILL BE
ON THE INCREASE THROUGH THE DAY. BLENDED PREVIOUS TEMPS WITH NEW
MAV NUMBERS...YIELDING HIGHER NUMBERS THAN PREVIOUS.
OVERALL FAST WSW FLOW REMAINS IN PLACE THROUGH THE PERIOD. THIS
ALLOWS A QUICK-MOVING SHORTWAVE...IN THE U.S. SOUTHWEST AT 12Z
SATURDAY...TO RACE INTO THE OHIO VALLEY BY 12Z SUNDAY...AND THEN OFF
THE NEW ENGLAND COAST BY 12Z MONDAY. EXACT TIMING STILL AN
ISSUE...ALTHOUGH MODELS ARE MORE OR LESS IN AGREEMENT...LED BY THE
ECMWF. NOT MUCH OF A SURFACE REFLECTION WITH THIS SYSTEM UNTIL IT
IS OFFSHORE...MOST OF THE SUPPORT FOR LIFT COMES FROM WARM
ADVECTION...ISENTROPIC LIFT...AND RRQ OF H300 JET. MOISTURE AND
SUPPORT DO NOT ALIGN PERFECTLY. FOR INSTANCE...BRIEF SHOT OF
FRONTOGENESIS IN THE H500-H700 LAYER AROUND 06Z PRECEDES THE BEST
MOISTURE. THIS...ALONG WITH SPEED OF SYSTEM...SUGGEST OVERALL QPF
WILL BE RATHER LIGHT. STILL...MODEL CONSISTENCY SUGGESTS
LIKELY/CATEGORICAL POPS FOR THE SOUTHEAST HALF OF CWA SATURDAY NIGHT
AND SUNDAY.
STILL CONCERNED ABOUT FZRA POTENTIAL ALONG THE EASTERN SLOPES.
SOUTHEAST FLOW WILL INDUCE CAD FOR A PERIOD LATE SATURDAY NIGHT INTO
SUNDAY MORNING. THIS SHOULD NOT BE AS PRONOUNCED OR LONG-LIVED AS
THE PREVIOUS SYSTEM...AND STILL EXPECTING AROUND A TENTH OF AN INCH
OF ICE ACCUMULATION BEFORE RAIN CHANGEOVER. STRONG WAA SHOULD START
ERODING CAD BY 12Z SUN...WITH FZRA THREAT DONE BY NOON. MOST OTHER
AREAS WILL SEE JUST RAIN AS STRONG WARM ADVECTION ARRIVES BEFORE
PRECIP...ALTHOUGH SOUTHEAST OHIO MAY SEE A BRIEF MIX AT THE START.
WENT WITH A NONDIURNAL TEMPERATURE TRACE SATURDAY NIGHT...WITH
HOURLIES BASED ON THE NAM. AT OR BELOW THE COOLER MAV ON SUNDAY.
MAIN SHORTWAVE DEPARTS QUICKLY SUNDAY AFTERNOON/EVENING...ALTHOUGH
CONTINUING WARM ADVECTION MAY ALLOW LIGHT RAIN/DRIZZLE TO LINGER FOR
A TIME INTO SUNDAY NIGHT. HAVE SLIGHT CHANCE/CHANCE POPS FOR THIS.
THINK CWA IS DRY AT 12Z MONDAY AND REMOVED SLIGHT CHANCE POPS AT
THIS TIME. TIMING OF NEXT SYSTEM IS UNCERTAIN...BUT MAINTAINED
PRECIP CHANCES TOWARDS THE END OF THE DAY.
&&
.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
FORECAST WAS GENERALLY BASED ON HPC THINKING. A COLD FRONT WILL
PUSH EAST LATE MONDAY NIGHT/EARLY TUESDAY...WITH HIGH PRESSURE
SLOWLY BUILDING IN.
AS FRONT APPROACHES...MODELS INDICATE A WARM LATER WILL SPREAD NORTH
ACROSS THE REGION....SO PRECIP TYPE SHOULD DEPEND ON SURFACE TEMPS.
RAIN SHOULD PREVAIL WITH SOME AREAS OF FREEZING RAIN ACROSS THE
NORTHERN MOUNTAINS AS WELL AS PERRY COUNTY OH AT 12 UTC TUESDAY.
PRECIP SHOULD THEN TURN TO ALL RAIN AS THE SFC TEMPS WARM TUESDAY
AFTERNOON BEFORE TURNING BACK TO SNOW TUESDAY NIGHT.
PRECIPITATION SHOULD THEN GRADUALLY ACROSS THE LOWLANDS TUESDAY
NIGHT INTO WEDNESDAY. HOWEVER...SNOW SHOWERS SHOULD CONTINUE ACROSS
THE MOUNTAIN COUNTIES INTO THURSDAY AS NORTHWEST FLOW DEVELOPS.
PRECIPITATION CHANCES SHOULD THEN INCREASE ACROSS THE ENTIRE AREA
THURSDAY AS A MID-LEVEL SHORTWAVE APPROACHES.
GENERALLY WENT BELOW HPC NUMBERS FOR HIGHS FOR MONDAY/TUESDAY...AS
GUIDANCE WAS ON THE HIGH END OF THE ENSEMBLE NUMBERS...OR EVEN ABOVE
IT. OTHERWISE...MADE TWEAKS TO GUIDANCE TO MATCH UP BETTER WITH
NEIGHBORING OFFICES.
&&
.AVIATION /08Z FRIDAY THROUGH TUESDAY/...
06Z FRIDAY THRU 06Z SUNDAY...
VFR CONDITIONS AREA WIDE TONIGHT AND FRIDAY. GUSTY WINDS WILL SUBSIDE
ACROSS MANY LOCATIONS TONIGHT...EXCEPT OVER HIGHER TERRAIN AND
NORTHERN WV WHERE THEY WILL REMAIN. WESTERLY WINDS WILL BECOME GUSTY
AGAIN ON FRIDAY...ESPECIALLY OVER HIGHER TERRAIN...NORTHERN WV...AND
SE OHIO. GUSTS OF UP TO 24 KTS CAN BE EXPECTED OVER THE WV
LOWLANDS...WITH GUSTS OF UP TO 30 KTS OVER NORTHERN WV AND SE OHIO.
GUSTS OF UP TO 40 KTS CAN BE EXPECTED OVER THE HIGHER TERRAIN.
MODERATE TO STRONG WNW WINDS ALOFT.
AFTER 06Z SATURDAY...
IFR POSSIBLE IN RAIN SATURDAY NIGHT AND SUNDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...WIND CHILL ADVISORY UNTIL 10 AM EST THIS MORNING FOR WVZ046-
047.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...CL/SL
NEAR TERM...SL
SHORT TERM...CL
LONG TERM...JSH
AVIATION...SL
