FXUS62 KGSP 262324
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
624 PM EST THU NOV 26 2009
.SYNOPSIS...
HIGH PRESSURE WILL BE IN CONTROL DURING THE WEEKEND AND INTO EARLY
MONDAY. ANOTHER COLD FRONT WILL ARRIVE LATE MONDAY AND MONDAY
NIGHT. AS THAT FRONT STALLS OUT...LOW PRESSURE WILL TRACK NORTHEAST
ALONG THE FRONT FROM THE GULF TOWARD OUR AREA IN MID WEEK.
&&
.NEAR TERM /THROUGH FRIDAY/...
LATEST SURFACE ANALYSIS PLACES THE COLD FRONT ROUGHLY ALONG THE
NC/TENN BORDER...EXTENDING INTO NORTHWEST GA INTO SOUTHERN ALABAMA.
SOME LIGHT SHOWER ACTIVITY HAS DEVELOPED THIS AFTERNOON ACROSS THE
TENN VALLEY...SO SLT CHANCE POPS WILL BE MAINTAINED THROUGH EARLY
EVENING ACROSS THE MTNS. MODEL SOLUTIONS CONTINUE TO INDICATE AN
ENHANCEMENT IN MOISTURE OCCURRING ALONG THE FRONT AS IT MOVES INTO
THE PIEDMONT LATE THIS AFTERNOON/EARLY THIS EVENING...SO SLIGHT
CHANCES WILL BE MAINTAINED THERE AS WELL.
FREEZING LEVELS ACROSS THE MTNS WILL FALL OFF QUICKLY BEHIND THE
FRONT THIS EVENING...WITH SNOW LEVELS DROPPING TO ALL AREAS EXCEPT
THE VALLEY FLOORS BY MIDNIGHT. MEANWHILE...VEERING/STRENGTHENING
FLOW WILL RESULT IN A STRONG NW UPSLOPE COMPONENT BY MIDNIGHT. THE
BEST SUPERIMPOSITION OF NORTHWEST FLOW AND MOISTURE WILL OCCUR AFTER
MIDNIGHT...AND LIKELY TO CAT POPS APPEAR REASONABLE...WITH THE
HIGHEST POPS OCCURRING IN THE HIGH ELEVATIONS RIGHT ALONG THE TENN
BORDER. RELATIVE SHALLOWNESS OF THE MOISTURE AND UNFAVORABLE TEMP
PROFILE FOR GOOD SNOWFALL RATES SHOULD LIMIT ACCUMULATIONS TO 1-3
INCHES IN MOST AREAS FROM MADISON COUNTY NORTH. FURTHER SOUTH ALONG
THE TENN BORDER...ACCUMULATING SNOWS SHOULD BE LIMITED TO THE HIGHER
ELEVATIONS OF THE NEWFOUND MTNS/SMOKIES/CHEROHALA SKYWAY CORRDIOR.
WITH DEEPENING SURFACE LOW OFF THE ATLANTIC AND STRONG COLD
ADVECTION...WINDS REMAIN A CONCERN OVER THE MTNS TONIGHT. AT THIS
POINT...THE PREPONDERANCE OF THE EVIDENCE HAS ME LEANING AGAINST
UPGRADING TO A WARNING. THE NAM H8 WINDS OF 50-55 KT IN THE LEE ARE
NOTED. HOWEVER...THE NAM HAS TRADITIONALLY BEEN TOO AGGRESSIVE WITH
DOWNSLOPE WIND SPEEDS IN NW FLOW EVENTS OVER THE PAST COUPLE OF
SEASONS. ONE POTENTIAL FLY IN THE OINTMENT IS THE RECENT WET
WEATHER/MOIST SOIL CONDITIONS...WHICH COULD MAKE TREES MORE
SUSCEPTIBLE TO FALLING THAN WOULD BE USUAL. WE WILL MENTION THIS
POSSIBILITY IN THE WIND ADVISORY.
SNOW SHOWERS WILL END QUICKLY FRIDAY...AS UPPER TROUGH TRANSLATES
OVER THE REGION. THIS WILL PAVE THE WAY FOR A DRY/BREEZY/COOL FRIDAY
AFTERNOON IN MOST AREAS.
&&
.SHORT TERM /FRIDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 200 PM THU...ANY RESIDUAL NW FLOW MOISTURE WILL HAVE
DISSIPATED BY FRIDAY EVENING...HOWEVER...A TIGHT PRESSURE GRADIENT
WILL PERSIST ALONG WITH COLD ADVECTION ACROSS THE NRN NC MTNS. THE
WIND ADVISORY WILL BE EXTENDED FOR THE NRN MTNS UNTIL MIDNIGHT.
A FLAT RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE SOUTHEAST ON
SATURDAY. GOOD INSOLATION AND A NW DOWNSLOPING FLOW WILL ALLOW
PIEDMONT TEMPS TO WARM INTO THE 60S...WITH GENERALLY 50S ACROSS MOST
OF THE MTNS.
A POTENT SOUTHERN STREAM UPPER JETLET EMERGING FROM THE BAJA
PENINSULA WILL MOVE OVER THE SRN PLAINS ON SUNDAY...AND THEN RIDE UP
OVER THE FLATTENING SE RIDGE ON MONDAY. MOISTURE FROM THIS SRN
PINEAPPLE EXPRESS WILL INCREASE RAPIDLY ON SUNDAY ALONG A COLD FRONT
PUSHING SOUTHEAST INTO THE OH VALLEY...WITH MAINLY JUST AN INCREASE
IN MID AND HIGH CLOUDS FOR OUR FORECAST AREA. A DIGGING NRN STREAM
SYSTEM WAVE OVER THE GREAT LAKES WILL THEN PUSH THE FRONTAL ZONE
INTO THE FORECAST AREA MONDAY THROUGH MONDAY NIGHT. WILL RAMP CHC TO
LIKELY POPS UP FROM THE WEST ON MONDAY...WITH SHOTGUN SOLID CHANCES
ACROSS THE ENTIRE AREA WITH A LIKELY FROPA MONDAY NIGHT. THE GFS
APPEARS A LITTLE TOO AGGRESSIVE WITH COLD AIR BEHIND THE FRONT LATE
MONDAY NIGHT...BUT A HIGH ELEVATION RAIN/SNOW SHOWER MIX IN THE NW
FLOW IS POSSIBLE.
&&
.LONG TERM /TUESDAY THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THE GFS AND ECMWF ARE IN GOOD AGREEMENT IN
BRINGING DRIER AIR INTO THE REGION ON TUESDAY AS HIGH PRESSURE
FOLLOWS BEHIND A NORTHERN STREAM TROUGH. THE SOURCE REGION OF THE
HIGH APPEARS TO BE SOMEWHERE OVER THE NRN PACIFIC. EVEN THOUGH IT
WILL SEE SOME DRYING AS IT CROSSES THE CONUS...I DON/T THINK IT WILL
HAVE SUPER LOW DEWPOINTS. THIS IS IMPORTANT AS A SRN STREAM UPPER
LOW WILL QUICKLY EJECT ACROSS THE SRN MS RIVER VALLEY ON WED/THU IN
RESPONSE TO SIGNIFICANT HEIGHT FALLS OVER THE NRN TIER OF THE US.
AS THE LOW EJECTS...THE HIGH WILL TAKE ON A DAMMING CONFIGURATION
ACROSS THE REGION ON WEDNESDAY. ATTM...THOSE DEWPOINTS JUST DON/T
LOOK AS THOUGH THEY WILL BE COLD ENOUGH FOR MUCH IN THE WAY OF MIXED
PCPN. THE GFS BUFKIT SOUNDINGS SHOW A STRONG WARM NOSE AS THE LOW
EJECTS...WHICH DEFINITELY MEANS NO SNOW. THE EC IS EVEN FARTHER WEST
WITH THE LOW...IMPLYING AN EVEN WARMER AIRMASS. WE WOULD NEED THE
COLD AIR DAMMING PROCESS TO LOCK IN COLD DRY AIR NEAR THE SFC FOR
ANY KIND OF MIX. WITH THOSE MODIFIED PACIFIC DEWPOINTS...AND THE
FAIRLY TRANSITORY NATURE OF THE RIDGE...THIS APPEARS TO BE UNLIKELY.
OF COURSE...A BRIEF PERIOD OF MIX OVER THE MTN VALLEYS IS ALWAYS
POSSIBLE...BUT THAT/S SOMETHING TO REFINE CLOSER TO THE EVENT.
THURSDAY SHOULD SEE IMPROVING CONDITIONS AND FAIRLY MILD TEMPS AS
ALL THE COLD AIR WILL BE BACK OVER THE PLAINS UNDER THE AMPLIFYING
TROUGH OVER THE CENTRAL PART OF THE COUNTRY.
&&
.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
AT KCLT...SHOWERS TIMED TO BE EAST OF THE TERMINAL BY 00 UTC.
MID-LVL CLOUDS WILL DIMINISH THIS EVENING AND NW WINDS COULD BE
ACCOMPANIED BY LOW-AMPLITUDE GUSTS. ON FRIDAY...NW WINDS TO
BECOMING GUSTY DURING THE LATE MORNING HOURS AND CONTINUE INTO THE
AFTERNOON UNDER MOSTLY SUNNY SKIES.
ELSEWHERE ACRS THE FA...WELL MIXED...POST FRONTAL CAA REGIME...
TO INCREASINGLY LIMIT CLOUDS TO THE NC MTNS TONIGHT...WHERE THE
NW WIND GUSTS SHOULD BE MOSTLY LIMITED TO. OVER KAVL...THERE REMAINS
THE POSSIBILITY OF DEVELOPING MVFR CIGS TONIGHT AS WELL. CLEARING
OR REMAINING MOSTLY CLEAR ON FRIDAY...AS NW WIND GUSTS SPREAD FROM
THE MTNS TO THE LOWER ELEVATIONS.
OUTLOOK...BREEZY NORTHWEST WINDS WILL SHRINK BACK TO THE MTNS
FRIDAY EVENING. VFR CONDITIONS ARE EXPECTED THROUGH SUNDAY.
RESTRICTIONS ASSOCIATED WITH PRECIPITATION COULD OCCUR ON MONDAY
INTO TUESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...WIND ADVISORY UNTIL 6 PM EST FRIDAY FOR GAZ010.
NC...WINTER WEATHER ADVISORY UNTIL NOON EST FRIDAY FOR NCZ033-
048>053-058-059-501-503-505.
WIND ADVISORY UNTIL MIDNIGHT EST FRIDAY NIGHT FOR NCZ033-049-
050-501-503-505.
WIND ADVISORY UNTIL 6 PM EST FRIDAY FOR NCZ048-051>053-058-059-
062>065-507-509.
SC...NONE.
&&
$$
SYNOPSIS...DEO
NEAR TERM...JDL
SHORT TERM...HG
LONG TERM...MCAVOY
AVIATION...CSH/JDL
