000
FXUS61 KRNK 030559
AFDRNK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
159 AM EDT FRI SEP 3 2010

.SYNOPSIS...
HURRICANE EARL IS STILL ON TRACK TO MOVE NORTH...AND THEN
NORTHEAST...TRACKING ALONG THE MID ATLANTIC COAST LATE TONIGHT AND
FRIDAY MORNING. THE COLD FRONT WHICH WILL MOVE EARL NORTHEASTWARD
WILL MOVE THROUGH OUR REGION LATE FRIDAY AFTERNOON AND FRIDAY
NIGHT. THIS FRONT WILL BRING GUSTY WEST WINDS..AND DELIVER MUCH
COOLER AND DRIER WEATHER FOR THE WEEKEND.

&&

.NEAR TERM /THROUGH TODAY/...
MID AND HIGH CLOUD CANOPY ASSOCIATED WITH THE WESTERN EDGE OF THE
MOISTURE SHIELD ASSOCIATED WITH EARL HAS BACKED INTO MUCH OF THE
EAST THIS EVENING WITH EVEN A FEW SPRINKLES ACROSS THE FAR SE.
LATEST CANADIAN CLOUD DEPICTION HANDLES THIS WELL AND KEEPS SOME
DEGREE OF CLOUDS ALONG/EAST OF THE BLUE RIDGE UNTIL LATE WHEN THE
CENTER OF EARL PASSES WELL TO THE EAST AND TRAJECTORIES START TO
TURN MORE NW. ALTHOUGH NOT EXPECTING MUCH RAINFALL AS DEEPER RH
LOOKS TO STAY CLOSER TO THE COAST...UPDATING TO INCLUDE A FEW
SPRINKLES SE AND TO GO WITH MORE CLOUDS ESPCLY EAST INTO THE EARLY
MORNING HOURS. ELSW WILL MAINTAIN CLEAR TO PC OVERNIGHT WITH
MAINLY HIGH CLOUDS AROUND. WITH MORE CLOUDS...EXPECT LOW TEMPS
OVER THE EAST TO STAY A BIT WARMER SO UPPED LOWS A FEW DEGREES
ESPCLY PIEDMONT WHERE DEWPOINTS REMAIN HIGHER.

PREVIOUS DISCUSSION BELOW...

ALL EYES ARE ON EARL TONIGHT AS IT REMAINS ON TRACK TO MOVE OFF
SHORE PARALLEL TO THE OUTER BANKS LATE TONIGHT...AND THEN
ACCELERATE NORTHEASTWARD UP THE ATLANTIC COAST. THIS WILL HAVE
LITTLE AFFECT ON THE FORECAST AREA...OTHER THAN TO PROVIDE A BOOST
TO THE WINDS ASSOCIATED WITH THE SFC FRONT WHICH WILL MOVE THROUGH
THE AREA FROM ROUGHLY 500 PM IN THE MTNS...TO MIDNIGHT IN THE
PIEDMONT. STRONGEST WINDS WILL BE BEHIND THE FRONT BEGINNING
FRIDAY NIGHT...BUT INCREASED SUBSIDENCE ON THE PERIPHERY OF EARL
MAY HELP INCREASE THE WINDS FRIDAY AFTERNOON IN THE PIEDMONT. I
HAVE INCREASED THE WINDS TO BETWEEN 10 AND 15 MPH...WITH
AFTERNOON GUSTS OF 20 TO 25 MPH. HOWEVER..WITH LIGHT WINDS
TONIGHT...ESPECIALLY IN THE MTNS...AND CLEAR SKIES...I HAVE
MAINTAINED LOW TEMPS COOLER THAN GUIDANCE IN THE MTN VALLEYS.

SATELLITE DERIVED PWATS SHOWS A GOOD INFLUX OF MOISTURE NORTHWARD
AHEAD OF THE FRONT...AND CURRENT RADAR SHOWS A SOLID BAND OF
SHOWERS/SCT TSTMS AHEAD OF THE FRONT. THINK THAT THERE WILL BE AT
LEAST A BROKEN LINE OF SHOWERS MOVG INTO THE MTNS...WHICH WILL
QUICKLY DISSIPATE AS IT MOVES PAST THE WESTERN SLOPES WITH A
BRISK LOW LEVEL WEST WIND. HAVE INCREASED THE POPS TO LIKELY ON
THE WESTERN SLOPES OF SE WV...BUT KEPT THE LOW CHC OR SLIGHT CHC
POPS WE HAD FURTHER EAST INTO THE MTNS. LESS THAN 15 PCT CHC IN
THE FOOTHILLS AND PIEDMONT. HIGHS FRIDAY WILL STILL BE WARM TO
HOT...WITH PLENTY OF SUN...ALONG WITH SUBSIDENCE AND DOWNSLOPE
WINDS IN THE PIEDMONT.

&&

.SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/...
EARL WILL SPIN BY TO THE NORTHEAST FRIDAY NIGHT AS IT GETS PICKED UP
BY THE UPPER TROUGH PUSHING FROM THE WEST. WINDS FRIDAY NIGHT INTO
SATURDAY WILL BECOME GUSTY ESPECIALLY ALONG THE MOUNTAIN TOPS. CROSS
SECTION SUGGESTED UP TO 35 KNOTS ALONG THE RIDGE TOPS...THUS HAVE
INCREASED SUSTAINED WINDS AND GUSTS FRIDAY NIGHT THROUGH 00Z SUNDAY.
ANTICIPATING GUSTS COULD REACH 30 TO 35 MPH. STRONGEST WINDS IN THE
PIEDMONT WILL BE DURING THE DAY SATURDAY WITH MIXING.

A SURFACE COLD FRONT WILL ARRIVE FROM THE WEST WITH MAINLY THE
WESTERN SLOPES GETTING MOST OF THE PRECIPITATION. WITH A WEST
WIND...EXPECT THE PRECIP TO BREAK UP WHILE CROSSING THE MOUNTAINS
LATE. DO NOT EXPECT ANY PRECIP LASTING MUCH PAST 00Z SATURDAY.

SURFACE HIGH PRESSURE WILL BUILD IN FROM THE SOUTHWEST THROUGH
SUNDAY NIGHT. THIS WILL RESULT IN LOWERING DEWPOINTS AS DRIER AIR
ENTERS THE FORECAST AREA. THEREFORE...EXPECTING REFRESHINGLY COOLER
AND DRIER WEATHER THROUGH THE SHORT TERM.

WITH COOL AIR ADVECTION MOVING IN BEHIND THE FRONT...TEMPERATURES
ARE EXPECTED TO BE BELOW SEASONAL NORMS WITH THE COOLEST TIME BEING
SATURDAY AND SATURDAY NIGHT.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
HIGH PRESSURE ALOFT WILL BUILD INTO THE AREA MONDAY NIGHT INTO
TUESDAY BEHIND THE UPPER TROUGH MOVING OFF INTO THE ATLANTIC. 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 /06Z FRIDAY THROUGH TUESDAY/...
OVERALL CONDITIONS WILL PRIMARILY BE VFR THROUGH MUCH OF THE TAF
PERIOD.

HURRICANE EARL IS STILL ON TRACK TO SKIRT BY TO THE EAST OF THE
NC OUTER BANKS THIS MORNING AND THEN ACCELERATE NORTHWARD AWAY FROM
THE REGION. THE WESTERN PERIMETER OF THIS SYSTEM HAS RESULTED IN
SHIELD OF MID/HIGH CLOUDS INLAND AND AS FAR WEST AS THE BLUE
RIDGE. RAIN HOWEVER...IS CONFINED TO THE TIDEWATER AREA OF VA.
WINDS OVER WRN VA AND SOUTHEAS WV REMAIN LIGHT...SO NOT OUT OF
THE QUESTION FOR BRIEF PERIOD OF EARLY MORNING FOG WHERE SKIES ARE
CLEAR WEST OF THE UPPER LEVEL CLOUD SHIELD FROM EARL...ESP THE MTN
VALLEY TERMINALS SUCH AS KLWB. AS SUCH...MAINTAINED A TEMPO GROUP
FOR KLWB FOR LOWER VSBYS TOWARD DAYBREAK.

ONCE EARL PASSES TO THE NE FRIDAY...WILL SEE SUBSIDENCE AND
MIXING AHEAD OF THE UPSTREAM COLD FRONT ENHANCE WINDS...WITH GUSTS
TO 25 KTS OR BETTER POSSIBLE DURING THE AFTERNOON.

A COLD FRONT ARRIVES IN THE FAR WEST LATE FRIDAY AFTERNOON AND
COULD BRING SOME BRIEF MVFR VSBYS/CIGS WITH SHOWERS AND ISOLD
TSRA TO KLWB/KBLF...MAINLY AFTER 5-6 PM. SINCE MOST MODEL GUIDANCE
HAS SOME COVERAGE OVER SE WVA TOWARD THE END OF THE TAF
PERIOD...INCLUDED A CB MENTION AT BOTH KLWB/KBLF. 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
KROA...KLYH OR KDAN. UPSLOPE CLOUDINESS IN THE NORTHWEST FLOW
BEHIND THE FRONT MAY DEVELOP ALONG THE WESTERN SLOPES OF THE MTNS
FRIDAY NIGHT...WITH POTENTIAL IMPACT TO KBLF/KLWB WITH SUB VFR
CIGS. A PERIOD OF STRONGER WINDS WILL FOLLOW THE FRONTAL PASSAGE
FOR FRIDAY NIGHT AND SATURDAY. WIND GUSTS OF 25-30 KTS ARE
POSSIBLE ALONG THE RIDGES...AND WILL LIKELY IMPACT KROA.

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 INTO FRIDAY RELATIVE
HUMIDITY MINIMUMS OF NEAR 25 PERCENT CAN BE EXPECTED IN THE
FOOTHILLS AND PIEDMONT FRIDAY AFTERNOON. THE LOW HUMIDITY WILL
FAVOR CONTINUED DRYING OF BOTH THE LARGE AND FINE FUELS. DUE TO
THE LACK OF WIND TONIGHT THERE WILL AGAIN BE EXCELLENT HUMIDITY
RECOVERY ...BUT THIS WILL CHANGE FRIDAY NIGHT AFTER A COLD FRONT
PASSES THROUGH WITH STRONG WINDS BEHIND IT. THE STRONGER WINDS
WILL CONTINUE INTO SATURDAY...AND DESPITE COOLER TEMPERATURES...
THE MINIMUM RELATIVE HUMIDITY WILL AGAIN DROP TO AS LOW AS 25
PERCENT IN THE FOOTHILLS AND PIEDMONT. THE ONLY RAIN EXPECTED WILL
BE ON THE WESTERN SLOPES IN THE MTNS.

FIRE CONCERNS WILL INCREASE DUE TO THE PERSISTENT LOW
HUMIDITY...VERY WARM TEMPERATURES...AND INCREASING WIND FRIDAY
AFTERNOON INTO SATURDAY AFTERNOON. HOWEVER...CRITICAL FIRE
WEATHER CONCERNS MAY BE MITIGATED DUE TO LACK OF LEAF LITTER PER
FACT THAT TREES ARE STILL IN FULL CANOPY.

&&

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

&&

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

NWS RNK Office Area Forecast Discussion