FXUS61 KRLX 111849
AFDRLX
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON WV
149 PM EST FRI DEC 11 2009
.SYNOPSIS...
HIGH PRESSURE YIELDS DRY AND WARMER WEATHER THROUGH
SATURDAY. ANOTHER SYSTEM PASSES SOUTHWEST TO NORTHEAST SUNDAY
MORNING. COLD FRONT TUESDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
NOT MUCH TO TALK ABOUT IN THE NEAR TERM. SFC HIGH WILL GRADUALLY
SLIDE EAST OF THE CWA THROUGH SAT. MID DECK FROM EARLIER TDY WILL
CONT TO SHIFT SOUTH AND EAST OF THE AREA THIS AFTN. WINDS SHOULD
FINALLY DIMINISH OVERNIGHT. THIS SHOULD ALLOW FOR A GOOD RADIATIONAL
COOLING SETUP. ONLY CAVEAT IS A MINOR PUFF AT TOP OF BL WITH A
FEW HIGH CLOUDS TOWARD DAWN. WAA WILL ALSO BE COMMENCING...WITH H85
TEMPS COMING UP TO ARND -5C BY MORNING. DIDNT GET TOO CARRIED
AWAY CONSIDERING...HOWEVER DID GENERALLY GO A FEW DEGREES BELOW
MAV...CLOSER TO LCL MOS. THIS GIVE LWR-MID TEENS OUTSIDE OF
MTNS...WITH SOME SINGLE DIGITS POSSIBLE ACROSS THE MORE PROTECTED
AREAS OF GREENBRIER VALLEY. TRIED TO CODE UP A NON-DIURNAL ACROSS
THE HIGHEST ELEVATIONS...IE SNOWSHOE...TO ACCOUNT FOR INCREASING
WAA BY MORNING.
HIGH AND MID CLOUDS WILL BE ON THE INCREASE
THROUGHOUT THE DAY SAT FRM SW TO NE...AS NEXT SYSTEM APPROACHES.
CODED UP A BLEND OF MET AND INHERITED NUMBERS FOR MAXT
SAT...GIVING LWR- MID 40S OUTSIDE OF THE MTNS.
&&
.SHORT TERM /SATURDAY NIGHT 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 FRIDAY/...
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 /19Z FRIDAY THROUGH WEDNESDAY/...
VFR THROUGH THE PERIOD COURTESY OF HIGH PRESSURE. SFC WINDS WILL
DIMINISH OVERNIGHT WITH GENERALLY LIGHT WINDS EXPECTED ON SAT. LIGHT
TO MODERATE WSW WINDS ALOFT SAT.
AFTER 18Z SATURDAY...
IFR POSSIBLE IN RAIN SATURDAY NIGHT AND SUNDAY.
&&
.RLX WATCHES/WARNINGS/ADVISORIES...
WV...NONE.
OH...NONE.
KY...NONE.
VA...NONE.
&&
$$
SYNOPSIS...MDP/ARJ/30
NEAR TERM...30
SHORT TERM...MDP
LONG TERM...ARJ
AVIATION...30
