FXUS61 KRNK 220504
AFDRNK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BLACKSBURG VA
1204 AM EST TUE DEC 22 2009
.SYNOPSIS...
HIGH PRESSURE WILL BUILD INTO THE MID ATLANTIC REGION TONIGHT
BRINGING AN END TO THE DRIZZLE AND LIGHT SNOW. AN AREA OF LOW PRESSURE
MOVING THROUGH THE EASTERN PLAINS THURSDAY...WILL BRING A CHANCE
OF FREEZING RAIN OR RAIN THURSDAY NIGHT AND FRIDAY ALONG WITH
GUSTY WINDS.
&&
.NEAR TERM /THROUGH TUESDAY/...
CLOUDS WILL REMAIN PERSISENT IN THE AREA WHERE THEY ARE RIGHT NOW
WITH MAYBE SOME DIMINISHING IN THE SOUTEHAST TOWARD 12Z. THEREFORE
INCREASED SKY COVER TO ACCOUNTY FOR THIS AND BUMPED LOWS UP SOME.
GETTING SOME MIX OF FREEZING DRIZZLE AND SNOW FLURRIES...DESPITE
DRYNESS IN THE BEST SNOW GROWTH ZONE...MORE LIKE SOLID PLATES TO
OR PRISMS.
WILL CONTINUE THE SPS FOR BLACK ICE.
TRANQUIL WEATHER ANTICIPATED TUESDAY AS WEAK SFC HIGH SHIFTS EAST. A
WEAK SHORTWAVE MOVING THROUGH THE UPPER ZONAL FLOW MAY BRING A FEW
HIGH/MID LEVEL CLOUDS...BUT TEMPS SHOULD BE A FEW DEGREES WARMER
WITH CLIMBING 1000-850MB THICKNESSES. HOWEVER...WENT BELOW GUIDANCE
FOR HIGHS IN SNOW COVERED AREAS.
&&
.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY NIGHT/...
SURFACE HIGH PRESSURE WILL HANG OVER THE FORECAST AREA WITH UPPER
LEVEL RIDGING OVER THE OHIO VALLEY. DRY WEATHER THROUGH THURSDAY IS
EXPECTED.
THE NEXT SYSTEM TO FOCUS ON WILL BE NEARING THURSDAY NIGHT. LOW
PRESSURE WILL DEVELOP ACROSS THE MIDWEST AND PUSH NORTHEAST OVER THE
GREAT LAKES...WHILE A SECONDARY LOW TRIES TO FORM ACROSS THE
SOUTHEAST BUT LOOKS TO REMAIN WEAK AT THIS TIME. THE LATEST MODEL
RUNS DIFFER SOMEWHAT WITH THE CANADIAN BEING THE FASTEST...THE ECMWF
BEING THE SLOWEST AND THE GFS ALSO FAVORING THE SLOWER TIMING. THE
MODELS HAVE BEEN CONSISTENTLY SLOWING DOWN THE TIMING OF THE SYSTEM
IMPACTING OUR COUNTY WARNING AREA. DUE TO THIS...HAVE DELAYED THE
PRECIP A FEW HOURS TO BEGIN 00Z FRIDAY.
MAX TEMPERATURES WILL BE IN THE UPPER 30S TO LOWER 40S ACROSS THE
BIGGEST PORTION OF THE FORECAST AREA WITH COLDER AIR FILTERING INTO
THE ALLEGHANY HIGHLANDS. THEREFORE...HAVE JUST ABOVE FREEZING AND
EXPECT FREEZING RAIN TO BEGIN IN THIS AREA AND EXPANDING
SOUTHWESTWARD FOLLOWING THE WEDGE OF HIGH PRESSURE.
THE MODELS INDICATE NORTHWESTERLY WINDS OF 60 TO 70 KNOTS AT 850MB
DEVELOPING OVER SOUTHEASTERN WEST VIRGINIA THURSDAY NIGHT. WIND
ADVISORY MAY BE POSSIBLE FOR THE WESTERN UPSLOPE REGIONS AS WIND
GUSTS COULD REACH INTO THE MID 30 MPH RANGE.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
MODELS CONTINUE TO SLOW DOWN EASTWARD PROGRESSION OF THE OCCLUDED
FRONT ON CHRISTMAS DAY WITH POSSIBLE TRIPLE POINT WAVE ON THE
BOUNDARY QUITE WEAK AT THIS POINT. PER THE SLOWER ECMWF...LIKE IDEA
OF A BETTER SWATH OF PRECIP ACROSS THE WESTERN HALF FRIDAY
MORNING...THEN INTO THE EAST DURING THE AFTERNOON/EVENING. LOOKS
LIKE THINGS WILL BE COLD ENOUGH ALONG THE BLUE RIDGE TO PRODUCE A
CONTINUED THREAT OF ICING THRU MID MORNING...THEN GRADUALLY
TRANSITIONING TO MAINLY A COLD RAIN BY MIDDAY MOST SPOTS. SINCE
TIMING ISSUES REMAIN ONLY BOOSTED TO LOW END CAT POPS OVER THE WEST
DURING THE MORNING WITH LIKELYS ELSW. 85H SELY JET OVER THE WEST
STILL PROGGED AT 50-60 KTS AROUND 12Z FRIDAY WITH RAOBS SHOWING SOME
OF THIS POSSIBLY MIXING TO THE SURFACE TAZEWELL/BLF REGION SO
BOOSTING SPEEDS INTO ADVISORY/WARNING CRITERIA AT ELEVATION. THUS
WILL KEEP MENTION IN THE HWO. DEEP RH CHASES OUT TO THE NE FRIDAY
NIGHT WITH LINGERING LIKELY POPS NE...DIMINISHING TO LOW CHANCE SW
THRU MIDNIGHT AS THE DRY SLOT KICKS IN AHEAD OF THE FRONT. MAY BE
ENOUGH LINGERING COLD AIR FOR SOME SPOTTY -FZRA FRIDAY EVENING
BEFORE COLDER ADVECTION ALOFT ARRIVES CHANGING WHATS LEFT OF THE
MOISTURE TO SNOW SHOWERS WEST. HIGHS FRIDAY TRICKY AS 85H TEMPS WARM
QUITE A BIT OVERTOP THE CAD BUT HOW MUCH OF THIS IF ANY MIXES DOWN.
POTENTIAL FOR WESTERN/SOUTHERN SPOTS TO REALLY ZOOM UP AS THE PRECIP
ENDS BUT GIVEN SNOW PACK AND STRONG WEDGE LI FEATURE OFF THE GFS
PLAYING MOST SPOTS WELL BELOW MOS FOR NOW.
5H TROF PIVOTING BY TO THE NORTH SHOULD ENHANCE UPSLOPE -SHSN A BIT
SAT INTO SAT NIGHT BUT GIVEN MORE OF A WESTERLY TRAJECTORY ONLY
CHANCE POPS WESTERN THIRD FOR NOW. MORE OF AN OVERALL ZONAL FLOW
WILL TAKE SHAPE LATER IN THE WEEKEND INTO EARLY NEXT WEEK ALLOWING
HIGH PRES TO BUILD IN FROM THE SW BY MONDAY. THUS OTHER THAN SOME
RESIDUAL UPSLOPE FLURRIES EXPECTING A DRY SCENARIO UNDER MORE SUN
FOR DAYS 6/7. TEMPS WILL REMAIN A BIT BELOW NORMAL SAT-MON ESPCLY AT
NIGHT BUT NOT TERRIBLY COLD AS THE ARCTIC AIR BASICALLY REMAINS
LOCKED UP TO THE NORTH AT THIS POINT.
&&
.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
WILL BE MORE PESSIMISTIC IN SKY COVER OVERNIGHT IN SE WV WITH MVFR
TO IFR CIGS EXPECTED. THINK CIGS WILL RISE TO MVFR DURING THE DAY
TUESDAY HERE...WITH MAYBE SOME BREAKS IN THE AFTN.
OTHERWISE...VFR CIGS WILL REMAIN AT THE REST OF THE TERMINALS WITH
CLEARING TAKING PLACE BETWEEN 12-16Z.
COLD HIGH PRESSURE WILL BUILD INTO THE REGION LATE TUESDAY NIGHT INTO
WEDNESDAY...GENERALLY SUPPORTING UNRESTRICTED VFR CONDITIONS AT
ALL TERMINAL FORECAST POINTS. HOWEVER...A POTENTIAL EXISTS FOR
SOME PATCHY OVERNIGHT/EARLY MORNING FOG GIVEN SNOW ON GROUND AND
SOME INCREASE IN TEMPERATURES AND MOISTURE ALOFT. BEST THREAT FOR
PATCHY FOG IN NORMALLY FAVORED MOUNTAIN VALLEYS AND NEAR WATERWAYS
(SUCH AS/NEAR KLWB) WILL BE ON WEDNESDAY AND THURSDAY MORNING.
ANOTHER STORM SYSTEM WILL LIKELY BRING ANOTHER ROUND OF MVFR TO IFR
CONDITIONS THURSDAY NIGHT INTO FRIDAY...WITH FREEZING RAIN AND/OR
RAIN THE MOST PROBABLE PRECIPITATION THREAT.
&&
.RNK WATCHES/WARNINGS/ADVISORIES...
VA...NONE.
NC...NONE.
WV...NONE.
&&
$$
SYNOPSIS...PH
NEAR TERM...PH/WP
SHORT TERM...REB
LONG TERM...JH
AVIATION...PH/WP
