FXUS61 KRNK 271653
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1153 AM EST FRI NOV 27 2009
.SYNOPSIS...
VERY GUSTY NORTHWEST WINDS AND MOUNTAIN SNOW SHOWERS BEHIND A STRONG
COLD FRONT WILL CONTINUE THROUGH 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 TONIGHT/...
RADAR SHOWING SNOW SHOWERS BECOMING MORE CONVECTIVE/BANDED IN NATURE
ATTM IN RESPONSE TO HEATING AND NEXT S/W ROUNDING THRU THE TROF.
THIS TREND SHOULD SUPPORT ANOTHER FEW HOURS OF DECENT SNOW SHOWER
COVERAGE MAINLY WESTERN GREENBRIER CTY WHERE ALTHO MAY NOT END UP
WITH ADVISORY CRITERIA PER WARM GROUND...EXPECT ANOTHER INCH OR TWO
POSSIBLE THRU MID AFTERNOON. ELSW...CURRENT DEPTH OF DECENT RH SEEN
ON 12Z RAOBS SHOULD BEGIN TO DIMINISH SOME AS SUGGESTED BY MOST
GUIDANCE WITH MOISTURE BECOMING TOO SHALLOW FOR SNOW FROM SOUTH TO
NORTH IN THE UPSLOPE AREAS DURING THE DAY. LATEST WRF AS MOST
COVERAGE CONFINED TO THE FAR NW PORTION OF THE CWA BY 20Z SO
TRIMMING BACK POPS MOST AREAS SOUTH OF LWB/BLF FOR THE AFTERNOON BUT
KEEPING THE ADVISORY FOR A WHILE LONGER. SOME CLOUDS MAY CONTINUE TO
LEAK EAST OF THE BLUE RIDGE BUT LIKELY WONT LAST LONG GIVEN MIXING
SO KEEPING TRENDS OF MAINLY SUNNY EAST TO PC BLUE RIDGE AND MOSTLY
CLDY NW. WINDS AGAIN THE BIGGER ISSUE WITH OBS NEAR WARNING CRITERIA
ATTM NW NC MOUNTAINS AND PICKING UP ELSW OVER THE WEST AS THE
INVERSION LOWERS AND MIXING ENHANCES DUE TO SOME SUN. ALSO LATEST
RAOBS SHOW ANOTHER SURGE OF 50-60 KNOTS JUST ABOVE THE BOUNDARY
LAYER AFFECTING MUCH OF THE AREA BY 18Z AND BEYOND. THUS THINKING
OF STARTING THE SECOND PART OF THE WIND ADVISORY THAT INITS THIS
EVENING WITH THE MORNING UPDATE WITH THE ADDITION OF SMYTH COUNTY.
OTRW BOOSTED TEMPS SOME GIVEN SOME READINGS NEAR THE FORECAST
HIGHS AND EXPECTED BETTER RISES OVER THE EAST WHERE SOME 50S
LIKELY.
PREVIOUS DISCUSSION BELOW...
RADAR MOSAIC AND SATELLITE INDICATED INITIAL SURGE OF DEEPER LOW
LEVEL MSTR AND SNOW SHWRS IS ARRIVING INTO WRN SLOPE EARLY THIS
MORNING...WITH SOME LIGHT ACCUMULATIONS EXPECTED TO BEGIN IN FAVORED
AREAS AND LAST THROUGH MOST OF TODAY IN WV. DEEPEST MSTR AND BEST
UPSTREAM TRAJECTORIES FAVOR FRMO BLF NORTHWARD...WITH VERY SHALLOW
MSTR AND SHORT LIVED PERIOD OF SNOW SHWRS NOW EXPECTED FOR FAR SW
AND NW NC MTNS. BACKED OFF SLIGHTLY ON SNOW ACCUM IN ALL
LOCATIONS...WITH NOW ONLY ABOUT AN INCH MAX ALONG FAVORED RIDGES IN
NC...AND ROUGHLY 2 TO 4 FROM FLAT TOP TO WRN GREENBRIER COUNTY. BY
MID AFTERNOON SNOW ACCUM SHOULD BE TAPERING OFF EVEN IN WRN
GREENBRIER AS MSTR REALLY GETS SHALLOW...BUT LINGERING SNOW SHRWS
WITH VERY MINOR ADDITIONAL ACCUM EXPECTED TO CONTINUE UNTIL AROUND
MIDNIGHT. KEEPING SNOW AND BLOWING SNOW ADV IN PLACE ABOVE 3000 FEET.
BIGGER STORY IS PROBABLY THE STRONG NW WINDS BEHIND THE FRONT...WITH
MODELS CONTINUIING TO INDICATE INCREASING GRADIENT AROUND
850MB...AND THEN STRONG SUBSIDENCE DEVELOPING LATE TODAY AND
OVERNIGHT...WHICH SHOULD KEEP POCKETS OF STRONG GUSTS AND POSSIBLE
MTN WAVE ACTION GOING UNTIL GRADIENT FINALLY BEGINS TO WEAKEN TOWARD
DAWN. MUCH OF THIS IS IN RESPONSE TO DEEPENING SFC CYCLONE OFF NEW
ENGLAND COAST WITH SFC HIGH PRESSURE EASING UP FROM THE SOUTHWEST.
TYPICAL CLIMATOGICAL PATTERN FOR HIGH WIND EVENTS HERE. SO EXTENDED
HIGH WIND WARNING AND WIND ADVISORY THROUGH TONIGHT AND ALSO
EXPANDED WIND ADV FOR TONIGHT TO INCLUDE HIGHER RIDGES IN SW VA UP
THROUGH BATH COUNTY.
OTHERWISE...LOWERED DEW PTS A FEW DEG IN THE EAST GIVEN DOWNSLOPE
AND VERY DRY MET GUIDANCE...MAYBE TOO DRY. AS FAR AS
TEMPS...GUIDANCE WAS ALL VERY SIMILAR...AND BASICALLY WENT SLIGHTLY
ABOVE IN THE EAST TO TAKE INTO ACCOUNT DOWNSLOPE AND AT OR JUST
BELOW IN THE WEST GIVEN STRONG CAA. WENT WITH GUIDANCE FOR MINS
TONIGHT...AND DESPITE CLEARING SKIES IN ALL BUT FAR WEST MIXING
SHOULD STAY UP EVERYWHERE.
&&
.SHORT TERM /SATURDAY THROUGH MONDAY NIGHT/...
RIDGING AT THE SURFACE AND ALOFT CROSS EAST OVER THE AREA GIVING WAY
TO DRY WEATHER AND WARMER TEMPERATURES THROUGH SUNDAY.
A COLD FRONT WILL APPROACH THE REGION SUNDAY NIGHT INTO MONDAY.
THERE ARE TIMING AND LOCATION DIFFERENCES WITH THE LATEST RUNS OF
THE GFS AND THE ECMWF. THE GFS IS FAIRLY PROGRESSIVE WITH BRINGING
THE SURFACE FRONT THROUGH THE FORECAST AREA MONDAY AFTERNOON WHILE
THE ECMWF IS APPROXIMATELY 6 HOURS SLOWER. BEGAN SLIGHT CHANCE POPS
EARLY MONDAY MORNING AND INCREASING TO LIKELY BY AFTERNOON IN
SOUTHEAST WEST VIRGINIA. MAINTAINED THE LIKELY CATEGORY ALONG AND
WEST OF THE BLUE RIDGE MOUNTAINS THROUGH LATE MONDAY NIGHT...WHILE
CHANCE POPS REMAIN IN THE EAST.
NORTHWESTERLY FLOW WILL BRING A PUSH OF COLD AIR INTO THE COUNTY
WARNING AREA IN THE WAKE OF THE SYSTEM. BUFKIT SOUNDINGS SUPPORT
BELOW FREEZING TEMPERATURES ALL THE WAY DOWN TO THE SURFACE AT
BLUEFIELD AND LEWISBURG BUT AGAIN MOISTURE WILL BE LIMITED. DUE TO
THE FORECAST SOUNDINGS...NORTHWEST FLOW REGIME AND TEMPERATURES
DROPPING TO NEAR FREEZING MONDAY NIGHT...ANOTHER CHANCE FOR SOME
LIGHT SNOW SHOWERS IN THE WESTERN UPSLOPE REGION IS NOT OUT OF THE
QUESTION.
MIN TEMPERATURES WILL DROP INTO THE UPPER 30S SUNDAY NIGHT WITH LOWS
FALLING TO NEAR FREEZING MONDAY NIGHT. HIGH TEMPERATURES WILL RUN
ABOVE NORMAL THROUGH MONDAY...WHILE LOWS WILL STICK AROUND SEASONAL
NORMS THROUGH THE PERIOD.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
THE NEXT CHANCE FOR RAIN NEXT WEEK WILL BE WEDNESDAY. THIS EVENT
WILL BE MAINLY AN OVERRUNNING EVENT THAT COULD LINGER INTO THURSDAY
MORNING. WILL HAVE ABUNDANT GULF MOISTURE ASSOCIATED WITH IT AND
MODERATE RAIN COULD FALL. TEMPERATURES MONDAY WILL RUN ABOVE NORMAL
WITH THE FRONT MOVING SLOWLY TO THE EAST. AS TYPICAL WITH AN AUTUMN
SEASON OVER RUNNING EVENT...WEDNESDAY AFTERNOON TEMPERATURES WILL BE
ABOUT 10 DEGREES BELOW NORMAL. FOR THE MOST PART...TEMPERATURES
SHOULD REMAIN ABOVE FREEZING WHEN THE RAIN IS FALLING. WILL NEED TO
WATCH TUESDAY NIGHT/WEDNESDAY MORNING TEMPERATURES AND DEW POINTS
BECAUSE IF RAIN ENTERS PRIOR TO DAWN...FROZEN P-TYPE IS POSSIBLE. AT
THIS TIME...GROUND TEMPERATURES STILL FAIRLY MILD...IN THE 40S.
&&
.AVIATION /18Z 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/SK/WP
SHORT TERM...JH/REB
LONG TERM...RCS
AVIATION...JH/SK
