FXUS62 KGSP 271910
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
210 PM EST FRI NOV 27 2009
.SYNOPSIS...
HIGH PRESSURE WILL REMAIN OVER THE AREA THROUGH THE WEEKEND AND
ALLOW TEMPERATURES TO REACH A FEW DEGREES ABOVE NORMAL. ON
MONDAY...A COLD FRONT WILL APPROACH THE CAROLINAS AND NORTHEAST
GEORGIA...AND CROSS EAST OF THE REGION THROUGH THE DAY. HIGH
PRESSURE WILL AGAIN BUILD BACK IN UNTIL A STORM SYSTEM APPROACHES
FROM THE SOUTH WEDNESDAY.
&&
.NEAR TERM /THROUGH SATURDAY/...
TAKING A GANDER AT UNOFFICIAL/SUPPLEMENTAL OBSERVING STATIONS...IT
APPEARS THAT MARGINAL WIND ADVISORY CRITERIA ARE STILL BEING REACHED
FROM TIME TO TIME ACROSS OUR NORTHERN MOUNTAIN ZONES. WE WILL
CONTINUE THE ADVISORY THROUGH THE OVERNIGHT...AS MODELS DEPICT A
RESURGENCE OF H8 WINDS THIS EVENING. HOWEVER...THIS IS LIKELY TO BE
ALMOST EXCLUSIVELY A HIGH ELEVATION EVENT...AS THE PRESSURE GRADIENT
ACROSS THE MOUNTAINS WILL BE QUITE WEAK BY EVENING. FURTHER SOUTH
AND WEST...WINDS AREN/T HIGH ENOUGH TO WARRANT CONTINUATION OF THE
ADVISORY. IN FACT...EVEN AN LWA MAY BE A BIT OF A STRETCH. WE HAVE
OPTED TO CANCEL THE CURRENT LWA...AND REPLACE THE WIND ADVISORY FOR
THE REMAINDER OF THE SRN/CTRL MTNS WITH A LWA.
OTHERWISE...TONIGHT IS GOING TO BE CHILLY...THE COOLEST OF THE
SEASON SO FAR. IN FACT...IT APPEARS THAT WIDESPREAD FREEZING TEMPS
WILL FINALLY AFFECT THE PIEDMONT AND FOOTHILLS FOR THE FIRST TIME
THIS SEASON. CONSIDERING THE EXISTENCE OF IDEAL RADIATIONAL COOLING
CONDITIONS...THE COOLEST NUMERICAL GUIDANCE HAS BEEN UNDERCUT BY A
COUPLE OF DEGREES FOR TONIGHTS MINS.
ANOTHER DRY/SUNNY AND SEASONABLY COOL DAY IS ANTICIPATED FOR
SATURDAY...JUST SLIGHTLY WARMER AND LESS BREEZY THAN TODAY.
&&
.SHORT TERM /SATURDAY NIGHT THROUGH TUESDAY NIGHT/...
AS OF 2 PM FRI...A DEEP CLOSED LOW WILL BE IN PLACE OVER THE EXTREME
SW CONUS SAT NIGHT...WITH A NRN STREAM SYSTEM DIGGING INTO THE NRN
PLAINS. WEAK UPPER SHORTWAVES ARE EXPECTED TO EJECT NE TOWARD THE
AREA FROM THE SW SYSTEM SAT NIGHT INTO SUN...BUT DAMPEN OUT AS THEY
APPROACH THE AREA. SOME INCREASE IN MID AND HIGH LEVEL CLOUDS IS
EXPECTED ON SUNDAY...ESPECIALLY IN WRN SECTIONS...BUT WITH HIGHS
STILL REACHING WELL INTO THE 60S MOST AREAS.
THE NRN STREAM ENERGY WILL THEN BECOME THE DOMINANT FEATURE SUN
NIGHT INTO MON...AS A TROUGH DIGS THROUGH THE MIDWEST AND MOISTURE
FROM THE DEEP SW FETCH POOLS ALONG AN ASSOCIATED COLD FRONT. MODEL
CONSENSUS IS NOW SLIGHTLY FASTER WITH THE FRONTAL ZONE
MOISTURE...DEPICTING IT APPROACHING THE WRN NC MOUNTAINS AROUND
DAYBREAK MON...BUT WITH THE DEEPER MOISTURE AND THE COLD FRONT
ARRIVING MON AFTN. UPPER DVPA WITH THE NRN STREAM TROUGH WILL CROSS
THE AREA ON MON NIGHT...BUT WITH SOME POST FROPA DRYING FROM THE NW
LIKELY UNDERWAY AT THIS POINT. WILL FEATURE THE BEST SOLID CHANCE TO
LOW LIKELY POPS MAINLY MON AFTN.
NW FLOW MOISTURE AND VERY COLD PROFILES APPEAR A BIT OVERDONE LATE
MON NIGHT ON THE GFS. LEANING TOWARD A CONSENSUS SOLUTION...WILL
ONLY ADVERTISE SLIGHT CHANCES OF A BRIEF RAIN/SNOW HIGH ELEVATION
MIX IN THE NRN MTNS EARLY TUE. A BRIEF RECOVERY IN HEIGHTS IS THEN
ANTICIPATED TUE AS THE SW SYSTEM SLOWLY MIGRATES INTO W TX. SOME
GRADUAL MOISTURE RETURN OVER THE BOUNDARY IS EXPECTED LATER IN THE
DAY.
&&
.LONG TERM /WEDNESDAY THROUGH FRIDAY/...
AS OF 205 PM FRIDAY...HPC IS ONCE AGAIN FAVORING THE ECMWF FOR THE
EXTENDED PART OF THE FORECAST. IT LIFTS THE SRN STREAM LOW FARTHER
TO THE WEST...AND MAINTAINS A STRONGER MID LEVEL VORTEX...THAN DOES
THE GFS. IT DOES THIS AS IT IS DEEPER AND FARTHER WEST WITH THE
STRONG NRN STREAM LONG WAVE TROUGH THAT DEVELOPS OVER THE NRN AND
CENTRAL PLAINS STARTING IN MID WEEK. THE LATEST GFS ENSEMBLE MEMBERS
SURE ARE IN GOOD AGREEMENT WITH THE OPERATIONAL GFS...BUT I/LL GO
ALONG WITH HPC/S GUIDANCE GRIDS FOR THE MOST PART FOR THIS PACKAGE.
THERE HASN/T BEEN MUCH CHANGE RUN TO RUN WITH THE AIRMASS
CHARACTERISTICS OF THE SFC RIDGE THAT WILL BE IN PLACE OVER THE
REGION AS THAT SRN STREAM ENERGY LIFTS TO OUR WEST. THE HIGH IS OF
MODIFIED PACIFIC ORIGIN...AND SHOULDN/T HAVE VERY LOW DEWPOINTS. THE
RIDGE IS ALSO PROGRESSIVE AND NOT WELL ANCHORED BY AND DOWNSTREAM
MID-TROPOSPHERIC CONVERGENCE. THEREFORE...THE BULK OF THE PCPN WITH
THE EVENT ON WED SHOULD BE A CHILLY...STRATIFORM RAIN. I DO HAVE
SOME MIX EARLY IN THE DAY OVER THE MTNS AS THE AIRMASS STARTS OUT
VERY DRY. THIS WILL ALMOST CERTAINLY LEAD TO A BRIEF PERIOD OF SNOW
OR SLEET...BUT IT WILL BE OF NO CONSEQUENCE.
THE LONG WAVE CONSOLIDATES INTO A STRONG UPPER LOW THU AND FRI AS IT
MOVES SLOWLY INTO THE GREAT LAKES STATES. THE DEEP LAYER FLOW WILL
BE OUT OF THE SW ON THURSDAY OVER OUR FA...AND WHILE THERE WILL BE A
STRONG TEMPERATURE CONTRAST BETWEEN THE MILDER AIR EAST OF THE MTNS
AND THE MODIFIED ARCTIC DRAPE TO THE WEST...TEMPS ACROSS MOST OF THE
FA SHOULD BE CLOSE TO NORMAL. THE FLOW WILL TURN A LITTLE MORE
WESTERLY THU NGHT AND FRI AS A SERIES OF WEAK UPPER LOWS RIDE UP THE
EAST SIDE OF THE CLOSED LOW. THIS MAY RESULT IN PERIODIC RAIN/SNOW
SHOWERS IN THE HIGH TERRAIN...PARTICULARLY IF THE NW FLOW IS STRONG
ENOUGH TO SATURATE THE AIRMASS ALONG THE WRN SLOPES. OVERALL IT WILL
BE A DRY AND COLDER DAY FOR FRI.
&&
.AVIATION /19Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT...DRY HIGH PRESSURE BUILDING INTO THE REGION WILL RESULT IN
CLEAR SKIES OVER THE NEXT 24 HOURS...LEAVING MAINLY A WIND FORECAST.
UNFORTUNATELY...A CROSS-RUNWAY...OR QUASI-CROSS-RUNWAY WIND IN THE
9-12 KT RANGE SHOULD PERSIST FOR MOST OF THE AFTERNOON. WIND SHOULD
EVENTUALLY BECOME SLIGHTLY NORTH OF DUE WEST...AND WILL FORECAST
THIS TO OCCUR AROUND 20Z.
ELSEWHERE...VFR CONDITIONS WILL CONTINUE THROUGH THE TAF PERIOD.
WEST/NORTHWEST WINDS OF 10-15 KT WILL PERSIST THROUGH THE AFTERNOON.
OCCASIONAL GUSTS TO AROUND 20 KT WILL BE POSSIBLE FROM TIME TO
TIME...BUT WILL BE MORE PERSISTENT AT KAVL. WINDS WILL BECOME LIGHT
AT MOST TERMINALS THIS EVENING.
OUTLOOK...DRY HIGH PRESSURE WILL DOMINATE THE AREA THROUGH SATURDAY
NIGHT AND WILL GRADUALLY WEAKEN ON SUNDAY. A COLD FRONT IS EXPECTED
TO REACH THE WESTERN CAROLINAS LATE SUNDAY NIGHT AND SWEEP ACROSS
THE REGION ON MONDAY...WITH PRECIPITATION AND RESTRICTIONS POSSIBLE.
CONDITIONS SHOULD IMPROVE ON TUESDAY.
&&
.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...WIND ADVISORY UNTIL 6 AM EST SATURDAY FOR NCZ033-049-050-501-
503-505.
LAKE WIND ADVISORY UNTIL 6 PM EST THIS EVENING FOR NCZ048-052-
053-059-063>065-507-509.
SC...NONE.
&&
$$
SYNOPSIS...SBK
NEAR TERM...JDL
SHORT TERM...HG
LONG TERM...MCAVOY
AVIATION...JDL
