136
FXUS61 KRNK 271943 AAA
AFDRNK
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE BLACKSBURG VA
243 PM EST FRI NOV 27 2009
SYNOPSIS
COLD NORTHWEST FLOW WILL KEEP VERY GUSTY WINDS AND MOUNTAIN SNOW
SHOWERS GOING INTO TONIGHT. HIGH PRESSURE WILL THEN BUILD EAST
ACROSS THE SOUTHEAST STATES DURING THE WEEKEND ALLOWING FOR A
MODERATION IN TEMPERATURES THROUGH SUNDAY. ANOTHER COLD FRONT WILL
ARRIVE ON MONDAY BRINGING A GOOD CHANCE OF RAIN TO MOST OF THE
REGION...WITH A FEW MOUNTAIN SNOW SHOWERS IN ITS WAKE.
NEAR TERM /THROUGH SATURDAY/
SNOW SHOWERS REMAIN QUITE LIGHT THIS AFTERNOON WITH WARM GROUND
TEMPS CONTINUING TO LIMIT ACCUMULATIONS TO JUST AN INCH OR TWO AT
THE HIGHEST PEAKS IN SE WVA. LAST IN A SERIES OF VORTS WILL SWING SE
AROUND THE DEPARTING UPPER TROF EARLY TONIGHT FOLLOWED BY SOME
INCREASE IN S/W RIDGING OVERNIGHT AS THE UPPER FLOW STARTS TO
FLATTEN. APPEARS ANY ADDED ACCUMULATING SNOWFALL WILL BE EARLY THIS
EVENING...MAINLY IN WESTERN GREENBRIER BEFORE THE AXIS OF DEEPER RH
SHIFTS TO THE NORTH. BANDED NATURE TO THE PRECIP MAY PRODUCE ANOTHER
INCH OR SO IN SPOTS ON THE RIDGES BUT ONLY PERIODIC -SHSN ELSW IN SE
WVA/WESTERN VA. THUS MAY CANCEL THE GOING WINTER WX ADVISORY EARLY
WITH THE AFTERNOON PACKAGE UNLESS GOING BANDS PERSIST. OTRW POPS MAINLY
ACROSS SE WVA WITH LIKELYS TAPERING TO ONLY ISOLATED ACROSS THE
GREENBRIER BY MIDNIGHT IF NOT SOONER. WINDS HOWEVER REMAIN A
BIGGER CONCERN ESPCLY THIS EVENING IN RESPONSE TO A LOWERING
INVERSION LEVEL AND NEXT SPIKE IN 85H WINDS WITH THE LAST S/W THIS
EVENING. LATEST FCST RAOBS DO SHOW A PERIOD THRU ABOUT 6Z WHERE
ANOTHER SURGE IN WINDS OCCURS AS THE GRADIENT AGAIN TIGHTENS
BETWEEN THE HIGH TO THE SW AND THE COASTAL LOW. THEREFORE WILL
KEEP THE GOING NPW IN PLACE THRU THE NIGHT ALTHO SPEEDS SHOULD BE
MUCH LIGHTER AFTER MIDNIGHT. STAYED A LITTLE ON THE WARMER SIDE
OF MOS LOWS GIVEN MIXING AS SOME OF THE RIDGES MAY EVEN RISE LATE
AS WARMER AIR ALOFT ADVECTS IN FROM THE WEST.
5H ZONAL FLOW DEVELOPS SAT WITH SURFACE HIGH PRESSURE BUILDING TO
THE SOUTH AND A WARMER WESTERLY FLOW TAKING SHAPE. DRY AIR AND
SUBSIDENCE SHOULD SUPPORT SUNNY SKIES WITH TEMPS SURGING BACK TO
NEAR 60 SOUTH AND 50-57 ELSW UNDER +8C 85H TEMPS.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/
RIDGING AT THE SURFACE AND ALOFT WILL MOVE EAST ACROSS OUR AREA
SATURDAY NIGHT AND SUNDAY. PLAYED TEMPERATURES CLOSE TO MOSGUIDEBC
FOR SATURDAY NIGHT AND SUNDAY. A COLD FRONT WILL APPROACH SUNDAY
NIGHT AND MOVE EAST ACROSS THE REGION MONDAY. DECIDED TO GO WITH THE
MORE PROGRESSIVE TIMING OF THE COLD FRONT SIMILAR TO THE SREF/GFS
OVER THE SLOWER ECMWF. NORTHWESTERLY FLOW WILL BRING A PUSH OF COLD
AIR INTO THE COUNTY WARNING AREA IN THE WAKE OF THE SYSTEM. WITH
SOUNDINGS STILL SUPPORT BELOW FREEZING TEMPERATURES ALL THE WAY DOWN
TO THE SURFACE IN THE NORTHWEST...WILL HOLD ONTO THE MENTION
OF SOME LIGHT SNOW SHOWERS IN THE WESTERN UPSLOPE REGION.
LOWS SUNDAY NIGHT WILL BE NEAR SEASONAL NORMALS WITH READINGS
FROM THE MID 30S TO THE LOWER 40S. HIGH TEMPERATURES ON MONDAY
WILL RUN FROM THE MID 40S IN THE NORTHWEST TO AROUND 60 IN
SOUTHSIDE. PLAYED LOWS MONDAY NIGHT NEAR HPCGUIDE FROM THE LOWER 30S
IN THE WEST TO NEAR 40 IN THE EAST.
LONG TERM /TUESDAY THROUGH THURSDAY/
FOLLOWING THE FRONTAL PASSAGE ON MONDAY... A SURFACE RIDGE WILL BUILD
INTO THE REGION WITH ZONAL FLOW ALOFT. DRY SEASONABLE WEATHER WILL
BE BRIEF AS THE NEXT STORM SYSTEM BRINGS RAIN TO THE AREA WEDNESDAY.
A DISTURBANCE WILL MOVE OUT OF THE GULF TUESDAY NIGHT AND OVER THE
AREA BY WEDNESDAY NIGHT. OVER RUNNING COLD RAIN SHOULD START
WEDNESDAY MORNING ALONG THE VA/NC BORDER...THEN SPREAD TO THE
NORTHEAST THROUGH THE DAY. MODELS STILL IN DISAGREEMENT TO WHETHER
THE UPPER LEVEL LOW IS THE DOMINATE FEATURE MOVING ACROSS THE OHIO
VALLEY...OR THE SURFACE LOW TRACKING ACROSS THE SOUTHEAST AND OFF
THE VA/NC COAST WEDNESDAY/THURSDAY MORNING. EITHER WAY...MEASURABLE
RAIN EXPECTED FOR THE ENTIRE AREA WITH BELOW NORMAL TEMPERATURES
EXPECTED WEDNESDAY. THE BASIC QUESTION TO BE ANSWERED WILL BE THE
AMOUNTS OF RAIN DURING THE EVENT. IF THE SURFACE LOW DOES
DOMINATE...BULK OF THE HEAVIER SHOWERS WILL BE EAST OF THE BLUE
RIDGE AND POSSIBLY NOT IN THE AREA AND MORE TOWARDS THE COAST.
TEMPERATURES ARE EXPECTED TO REMAIN ABOVE FREEZING FOR THIS EVENT TO
BE ALL RAIN. THURSDAY NIGHT INTO FRIDAY...MOISTURE ON THE BACK SIDE
OF THE SYSTEM AND COLD AIR FILTERING IN...COULD PRODUCE A FEW
MOUNTAIN SNOW SHOWERS/FLURRIES.
AVIATION /20Z FRIDAY THROUGH WEDNESDAY/
THROUGH LATE AFTERNOON...PERIODIC IFR TO MVFR CIGS IN SNOW SHWRS
AT BLF/LWB WITH MVFR TO VFR VSBYS AS SNOW SHOULD REMAIN RATHER LIGHT
AT THESE LOCATIONS. NEARBY HIGHER RIDGES WILL EXPERIENCE HEAVIER
SNOW SHOWERS ALONG WITH MOUNTAIN OBSCURATION. CIGS SHOULD LIFT
WITH SNOW SHOWERS ENDING BY 21-23Z...BRINGING VFR CIGS TO BLF AND
LWB FOR REMAINDER OF THE EVENING AND OVERNIGHT. THE MAIN AVIATION
IMPACT WILL BE THE STRONG NORTHWEST WINDS. LOOKING AT GUSTS AS
HIGH AS 40-45 KNOTS POSSIBLE INVOF ROANOKE AND 35 KTS AT BLF
.ESPECIALLY NEAR RIDGES. POSSIBLY SLIGHT WEAKENING OF WINDS
LATE THIS AFTERNOON BEFORE GUSTS PICK UP AGAIN OVERNIGHT IN AND
AROUND ROA MAINLY. WINDS AT LYH AND DAN AND LOCATIONS WELL EAST OF
THE BLUE RDG WILL SEE WINDS DIMINISH GRADUALLY OVERNIGHT TO LESS
THAN 10 KTS UNDER CLEAR SKIES. SAME SHOULD BE TRUE OF LWB IN THE
GREENBRIER VALLEY.
HIGH PRESSURE BUILDS BACK INTO THE REGION ON SATURDAY AND SUNDAY.
THIS WILL END ANY LINGERING THE UPSLOPE CLOUDS AND PRECIPITATION
WEST OF BLF AND LWB. NEXT FRONTAL SYSTEM WITH A CHANCE OF RAIN AND
POSSIBLE IFR CONDITIONS ARRIVES FROM THE WEST EARLY MONDAY. HIGH
PRESSURE FOLLOWS THE FRONT WITH VFR LIKELY IN THE TUE/WED TIMEFRAME.
RNK WATCHES/WARNINGS/ADVISORIES
VA...WIND ADVISORY UNTIL 6 AM EST SATURDAY FOR VAZ009>014-016>020-
022.
HIGH WIND WARNING UNTIL 6 AM EST SATURDAY FOR VAZ015.
NC...WIND ADVISORY UNTIL 6 AM EST SATURDAY FOR NCZ002.
HIGH WIND WARNING UNTIL 6 AM EST SATURDAY FOR NCZ001-018.
WV...WINTER WEATHER ADVISORY UNTIL 6 PM EST THIS EVENING FOR WVZ045.
SYNOPSIS...JH/SK
NEAR TERM...JH
SHORT TERM...KK
LONG TERM...RCS
AVIATION...JH/SK
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