000
FXUS61 KRNK 031653
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1253 PM EDT FRI SEP 3 2010

.SYNOPSIS...
HURRICANE EARL OFF THE MID ATLANTIC COAST WILL CONTINUE TO MOVE
NORTHEAST AND AWAY FROM THE REGION THROUGH THIS EVENING. A STRONG
COLD FRONT WILL MOVE SOUTHEAST OUT OF THE OHIO VALLEY AND ACROSS
THE AREA TONIGHT. THIS FRONT WILL BRING GUSTY WEST WINDS...WHILE
DELIVERING MUCH COOLER AND DRIER WEATHER FOR THE WEEKEND.

.NEAR TERM /THROUGH TONIGHT/...
HIGH CLOUD CANOPY ON THE WEST SIDE OF EARL CONTINUES OVER THE EAST
THIS MORNING AND MAY TAKE UNTIL THE AFTERNOON FOR THIS TO FADE AS
EARL HEADS FARTHER NE AND THE UPSTREAM FRONT APPROACHES. OTRW MAIN
CONCERNS FOR THE AFTERNOON WITH WINDS IN THE SUBSIDENCE WAKE
BEHIND THE DEPARTING COASTAL SYSTEM AND CONVECTIVE POTENTIAL IN
THE WEST ALONG THE FRONT LATER ON. WITH 25-30 KTS JUST OFF THE
DECK PER MORNING RAOBS...EXPECT HEATING AND BRIEF SINKING MOTION
TO PUSH GUSTS TO ABOVE 20 MPH THIS AFTERNOON BUT MAY BE LIMITED
MORE ACROSS THE EAST THAN EARLIER EXPECTED GIVEN CLOUDS SO TRIMMED
SPEEDS SLIGHTLY. SOUNDINGS CONTINUE TO INDICATE QUITE A BIT OF DRY
AIR ALOFT CAPPED BY A RATHER DEEP LAYER OF DOWNSLOPE IN THE WAKE
OF EARL. HOWEVER FCST RAOBS INDICATE A QUICK INCREASE IN
MOISTURE/THETA ADVECTION RIGHT AHEAD OF THE BOUNDARY OVER THE
MOUNTAINS LATER THIS AFTERNOON WITH 500-700 J/KG CAPES. LATEST
LOCAL WRF AND HRRR ALSO SHOW A BROKEN CONVECTIVE LINE ACROSS SE
WVA BETWEEN 4-8 PM AS THE TAIL OF PASSING UPPER JET WITH THE TROF
CLIPS BY. GIVEN RATHER STRONG UNIDIRECTIONAL FLOW ALOFT POTENTIAL
FOR GUSTY WINDS WITH ANY STORMS THAT POSSIBLY ORGANIZE SO
INCREASING POPS SOME WEST AND EDGING FARTHER EAST LATER ON GIVEN
STRONG WESTERLY FLOW. OTRW MORE SUN WEST EARLY AND OUT EAST DURING
THE AFTERNOON WITH HIGHS STILL 90-96 FOOTHILLS EAST PER DOWNSLOPE
AND WELL INTO THE 80S WEST GIVEN INSOLATION.

PREVIOUS DISCUSSION BELOW...

MAIN ACTION FROM HURRICANE EARL OCCURRING WELL EAST OF THE CWA
THIS MORNING. ASIDE FROM MID/HIGH CLOUDINESS ASSOCIATED WITH THE WESTERN
PERIPHERY OF THE STORM...NO IMPACT TO OUR CWA. HIGH CLOUDS SHOULD
EXIT THE CWA FORE NOON AS EARL CONTINUES TO TRACK NORTH AND AWAY
FROM THE AREA.

FOCUS FOR THE AFTERNOON AND EVENING WILL BE APPROACH OF STRONG
COLD FRONT THAT WILL BE CROSSING THE OHIO VALLEY. THIS FRONT IS
ASSOCIATED WITH A VIGOROUS UPPER LEVEL TROUGH OF LOW PRESSURE THAT
IS PLOWING ACROSS THE GREAT LAKES. THE FRONT IS THE LEADING EDGE
OF A COOLER DRIER AIRMASS THAT WILL INFILTRATE THE CWA TONIGHT.
WINDS AHEAD OF THE FRONT WILL INCREASE OUT OF THE WEST-
SOUTHWEST...THEN SHIFT WEST-NORTHWEST BEHIND THE FRONT TONIGHT.
WIND SPEEDS OF 10-15 MPH WILL BE COMMON TODAY AND MAY BECOME GUSTY
AHEAD OF THE FRONT THIS AFTERNOON. THE STRONGEST WINDS WILL LIKELY
OCCUR WITH THE FRONTAL PASSAGE...WIND GUSTS OF 20-25 MPH...THEN
PERSISTING IN THE HIGHER ELEVATIONS TONIGHT. POST FRONTAL MIXING
SHOULD PREVENT FOG/DEW FORMATION TONIGHT. THE ONLY WETTING MAY
COME FROM POTENTIAL SHOWERS/TSTMS THAT MAY FORM ALONG THE
FRONT...BUT LIMITED TO AREAS WEST OF THE BLUE RIDGE. THINK THESE
SHOWERS WILL QUICKLY DISSIPATE AS THE FRONT CROSSES THE
MOUNTAINS...WESTERLY DOWNSLOPE WINDS AND SUBSIDENCE SUPPORTING A
DRY SCENARIO EAST OF THE MOUNTAINS. AS SUCH...GOING FORECAST LOOKS
GOOD WITH HIGH CHC POPS FAR WESTERN CWA THIS EVENING TRANSITIONING
TO LITTLE OR NO PRECIP POTENTIAL EAST OF THE BLUE RIDGE.

TEMPS TODAY WILL CONTINUE TO BE VERY WARM. IF ANYTHING A WESTERLY
COMPONENT TO THE WIND AHEAD OF THE FRONT MAY ACTUALLY HELP BOOST
TEMPS A DEGREE OR TWO ABOVE MOS. AS FOR TONIGHT...TRANSITION WILL
TAKE PLACE AS COOLER DRIER AIRMASS ARRIVES. I DID NOT WANT TO GO
TOO COOL ON THE MIN TEMPS DUE TO POST FRONTAL MIXING WHICH MAY
PREVENT DECOUPLING AND RADIATIONAL PROCESS FROM COMING INTO PLAY.

.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
ON SATURDAY...MODEL GUIDANCE SUGGEST POST COLD FRONT 850 MB WINDS IN
THE 35 TO 40 KT RANGE ACCOMPANIED BY STRONG COLD AIR ADVECTION. THE
REGION...ESPECIALLY THE MOUNTAINS...WILL HAVE SOME THE STRONGEST
WIDESPREAD WINDS IT HAS HAD FOR A WHILE. GUSTS APPROACHING 30 TO 35
MPH AT THE HIGHEST RIDGE TOPS WILL BE COMMON THROUGHOUT THE DAY WITH
A TREND TOWARDS SLOWER SPEEDS IN THE AFTERNOON. ELSEWHERE IN THE
MOUNTAINS...GUSTS AROUND 25 MPH WILL BE COMMON WITH GUSTS OF 15 TO
20 MPH IN THE PIEDMONT. HIGHS ON SATURDAY WILL BE IN THE LOWER 70S IN
THE MOUNTAINS WITH READINGS AROUND 80 EAST OF THE BLUE RIDGE.

FROM SATURDAY NIGHT THROUGH MONDAY NIGHT THE TREND WILL BE FOR HIGH
PRESSURE TO START TO BUILD OVER THE MID WEST. THE RESULT FOR OUR
AREA WILL BE A DRY FORECAST AND A TREND TOWARDS MILDER TEMPERATURES
EACH DAY. BY MONDAY HIGHS OF LOWER 80S IN THE MOUNTAINS AND MID TO
UPPER 80S EAST OF THE BLUE RIDGE ARE EXPECTED. WINDS WILL BE LIGHT
AND VARIABLE THROUGH THE PERIOD BUT GRADUALLY TAKE ON MORE OF A
SOUTHERLY COMPONENT.

.LONG TERM /TUESDAY THROUGH THURSDAY/...
HIGH PRESSURE WILL ALSO REMAIN OVERHEAD AT THE SURFACE THROUGH
MID WEEK. WITH WINDS CLOCKING AROUND TO A SOUTH SOUTHEASTERLY
FLOW...DEWPOINTS WILL BE RISING AGAIN ALONG WITH WARMER
TEMPERATURES FOR THE FORECAST AREA. EXPECT WARM AND DRY WEATHER
THROUGH MOST OF THE EXTENDED. THE NEXT CHANCE OF PRECIP LOOKS TO
BE THE END OF THE WEEK AS ANOTHER FRONT IS ANTICIPATED TO APPROACH
THE COUNTY WARNING AREA.

TEMPERATURES WILL MODERATE TO ABOVE NORMAL NEXT WEEK.

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
VFR CONDITIONS ARE AGAIN EXPECTED TO PREVAIL THROUGH MUCH OF THE
VALID TAF TIME WITH ONLY BRIEF PERIODS OF MVFR ALONG AND BEHIND
THE FRONT ACROSS SE WVA INTO EARLY SAT. CLOUDS AHEAD OF THE FRONT
WILL INCREASE THRU LATE THIS AFTERNOON ACROSS THE WEST ALONG WITH
GUSTY WEST WINDS WHICH COULD TOP 25 KTS OR SO AT TIMES.

THE COLD FRONT SHOULD ARRIVE IN THE FAR WEST AROUND BLF/LWB BY
EARLY THIS EVENING AND COULD BRING SOME BRIEF MVFR VSBYS/CIGS WITH
SHOWERS AND ISOLD TSRA TO KLWB/KBLF...MAINLY AFTER 4-6 PM. SINCE
SHOWER CHANCES APPEAR A BIT BETTER BASED ON DEVELOPING COVERAGE TO
THE WEST INCLUDING A VICINITY SHRA MENTION AT KBLF/KLWB WITH CB
INCLUDED INTO EARLY THIS EVENING. MOISTURE WILL QUICKLY FADE AS
THE FRONT MOVES EAST OF THE RIDGES AND INTO STRONG DOWNSLOPE
MIXING...SO NO FLIGHT RESTRICTIONS IN SHOWERS EXPECTED AT KLYH OR
KDAN. HOWEVER IF THE CONVECTION IS A BIT SLOWER AND WINDS SUBSIDE
SOME BY EARLY EVENING...THEN POSSIBLE TO HAVE ISOLATED SHRA MAKE
IT AS FAR AS KROA BEFORE FADING. BEHIND THE FRONT...WILL SEE A SHOT
OF GUSTY W/NW WINDS AND DRYING TONIGHT BEFORE A PERIOD OF UPSLOPE
CLOUDINESS DEVELOPS IN THE NORTHWEST FLOW BEHIND THE FRONT ALONG
THE WESTERN SLOPES OF THE MTNS LATE. THIS COULD IMPACT KBLF/KLWB
WITH BRIEF SUB VFR CIGS TOWARD MORNING BUT NO LOWER THAN MVFR AT
THIS POINT GIVEN SUCH DRY AIR/MIXING. A PERIOD OF STRONGER WINDS WILL
FOLLOW THE FRONTAL PASSAGE FOR SATURDAY. WIND GUSTS OF 25-30 KTS
ARE POSSIBLE ALONG THE RIDGES...AND WILL LIKELY IMPACT KROA THRU
SATURDAY AFTERNOON.

HIGH PRESSURE WILL QUICKLY BUILD BACK OVER THE REGION BEGINNING
SATURDAY NIGHT AND EXTENDING INTO NEXT WEEK...PROVIDING
WIDESPREAD VFR CONDITIONS...WITH PERHAPS SOME MORNING VSBY RESTRICTIONS
AT KLWB AND OTHER RIVER VALLEYS DUE TO VALLEY FOG FORMATIONS.

.FIRE WEATHER...
VERY WARM DRY CONDITIONS WILL PERSIST TODAY WITH RELATIVE HUMIDITY
MINIMUMS OF NEAR 25 PERCENT ALONG AND EAST OF THE BLUE RIDGE THIS
AFTERNOON. THE LOW HUMIDITY WILL FAVOR CONTINUED DRYING OF BOTH
THE LARGE AND FINE FUELS. THE ARRIVAL OF A COLD FRONT THIS EVENING
WILL RESULT IN INCREASING WIND SPEEDS. WIND GUSTS OF 20 TO 25 ARE
LIKELY WITH THE FRONTAL PASSAGE...THESE WINDS PREVENTING ANY
SUBSTANTIAL RECOVERY OF THE RELATIVE HUMIDITY TONIGHT. BREEZY
CONDITIONS WILL CONTINUE SATURDAY...AND DESPITE COOLER
TEMPERATURES SATURDAY...THE RELATIVE HUMIDITY MAY STILL DROP TO
TO NEAR 25 PERCENT EAST OF THE BLUE RIDGE SATURDAY AFTERNOON.

RAIN CHANCES WITH THE FRONTAL PASSAGE THIS EVENING LOOK TO BE
MAINLY CONFINED TO THE MOUNTAINS. SCATTERED SHOWERS AND
A FEW THUNDERSTORMS ARE POSSIBLE FROM 400 TO 1000 PM THIS
EVENING IN THE MOUNTAINS...BUT THESE SHOWERS ARE EXPECTED TO
DISSIPATE AS THE FRONT MOVES EAST OF THE MOUNTAINS...ENCOUNTERING
DOWNSLOPE DRYING AND SUBSIDENCE.

FIRE CONCERNS WILL INCREASE THIS AFTERNOON AND PERSIST THROUGH
SATURDAY DUE TO THE VERY WARM TEMPERATURES TODAY...LOW HUMIDITY
THIS AFTERNOON AND SATURDAY AFTERNOON...POOR HUMIDITY RECOVERY
TONIGHT...AND ELEVATED WIND SPEEDS THIS AFTERNOON AND PERSISTING
THROUGH SATURDAY AFTERNOON. HOWEVER...CRITICAL FIRE WEATHER
CONCERNS MAY BE MITIGATED DUE TO LACK OF LEAF LITTER PER FACT THAT
TREES ARE STILL IN FULL FOLIAGE. THE CLOSED CANOPY WILL ALSO
SIGNIFICANTLY REDUCE WIND SPEEDS AT EYE LEVEL.

.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.

SYNOPSIS...JH/PM
NEAR TERM...JH/PM
SHORT TERM...DS
LONG TERM...REB
AVIATION...JH/PM
FIRE WEATHER...