FXUS62 KGSP 061822
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
222 PM EDT MON OCT 6 2008

.SYNOPSIS...
HIGH PRESSURE WILL REMAIN IN CONTROL ALONG THE EASTERN SEABOARD
THROUGH TUESDAY...BEFORE A STRONG COLD FRONT MOVES INTO THE WESTERN
CAROLINAS ON WEDNESDAY. MOISTURE FROM THIS FRONT WILL LINGER ACROSS
THE REGION THROUGH THURSDAY NIGHT...GRADUALLY DRYING OUT THROUGH THE
START OF THE WEEKEND. WEAK HIGH PRESSURE WILL THEN RETURN THROUGH
EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TUESDAY/...
A DEEP TROUGH AMPLIFYING OVER THE PLAINS STATES THIS AFTERNOON WILL
ALLOW A SHARP UPPER RIDGE AXIS TO PERSIST OVER THE SOUTHEAST THROUGH
TUESDAY. SLIGHTLY BETTER MOISTURE WILL ENCROACH UPON THE FORECAST
AREA FROM BOTH THE NORTH AND THE SOUTH THROUGH THE NEAR TERM. LOWER
LEVEL MOISTURE MOVING NORTH THROUGH GA LATE THIS AFTERNOON SHOULD
PIVOT TO THE WEST UNDER THE SURFACE RIDGE AND HAVE LITTLE IMPACT ON
THE SOUTHWEST ZONES. DEEPER MOISTURE ALONG THE BACKDOOR FRONT TO THE
NORTH SHOULD THIN SOMEWHAT AS THE BOUNDARY PUSHES SOUTHWARD INTO NC
TONIGHT THROUGH EARLY TUESDAY. VERY WEAK UPSLOPE AND ISENTROPIC LIFT
IN THE BETTER MOISTURE IS EXPECTED ALONG THE NORTHERN BLUE RIDGE
AFTER MIDNIGHT...AND THE PAST TWO RUNS OF THE NAM HAVE FEATURED
LIGHT PRECIPITATION AMOUNTS IN THAT AREA TOWARD DAYBREAK TUESDAY.
HOWEVER...SINCE THIS IS STILL NOT SUPPORTED BY THE SREF MEAN OR
GFS...WILL JUST MENTION ISOLATED SPRINKLES IN NW NC.

A SMALLER DIURNAL RANGE ON TEMPERATURES IS EXPECTED THAN OBSERVED
THE PAST FEW DAYS...WITH INCREASING CLOUDS FROM THE NORTH LATE
TONIGHT...AND THEN COOLER THICKNESSES SPILLING SOUTHWARD ON TUESDAY.
MOS CONSENSUS DEPICTS HIGHS GENERALLY IN THE 70S...EXCEPT IN THE 60S
ALONG THE RIDGE TOPS TUESDAY.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH FRIDAY NIGHT/...
AS OF 215 PM MONDAY...FORECAST FOR THE SHORT TERM WILL SHOW MORE
CONFIDENCE THAT WE WILL EXPERIENCE A WET PERIOD IN THE MID TO LATE
WEEK TIMEFRAME DESPITE SOME CONTINUED DISCREPANCIES BETWEEN THE
OPERATIONAL MODELS. ALL THE MODELS DEEPEN THE MIDWEST UPPER TROUGH
AND DEVELOP A CLOSED UPPER LOW OVER THE LOWER MISSISSIPPI VALLEY BY
WED. FROM THAT POINT ON...THERE IS QUITE A DISPARITY IN REGARD TO
THE MOVEMDENT OF THAT FEATURE. THE GFS REMAINS FAIRLY CONSISTENT
WITH ITSELF AND MOVES THE UPPER LOW SE INTO GA ON THU AND THEN KICKS
IT NE THROUGH THE CAROLINAS ON FRI. THE 12Z NAM TAKES THE UPPER LOW
TO GULF COAST NEAR THE FL PANHANDLE BY LATE THU...WHILE THE 00Z ECM
INITIALLY FOLLOWS A PATH SIMILAR TO THE GFS BUT ALLOWS THE LOW TO
LOSE MOMENTUM BY FRI AND STALL OVER THE SE. THE UPSHOT IS THAT I
DECIDED TO SIDE MORE CLOSELY TO THE GFS DUE ITS RUN TO RUN
CONSISTENCY. THEREFORE...WILL SHOW POPS SLOWLY INCREASING FROM W TO
E ACROSS THE FORECAST AREA TUE NIGHT AND WED. DID SLOW ONSET OF
PRECIP AS A NOD TO THE TOTALLY DRY NAM FOR WED. HOWEVER...MAV/MET
POPS QUITE HIGH SO HAVE SPREAD PRECIP ALL ACROSS THE AREA ON WED.
WIDESPREAD RAINFALL SHOULD OCCUR WED NIGHT AND THU WITH THE BULK OF
IT SHIFTING OFF TO THE E THU NIGHT...AND THEN ENDING ON FRI EXCEPT
FOR PERHAPS SOME SCATTERED LEFT OVER SHOWERS. WED/THU WILL BE COOL
DAYS WITH CONSIDERABLE CLOUDIENSS AND OFF AND ON SHOWERS. TEMPS WILL
TRY TO REBOUND ON FRI AS EXPECT SOME BREAKS IN THE CLOUD COVER WILL
OCCUR. USED A MOS BLEND FOR TEMPS WED...THEN GMOS/HPC FOR THU/FRI.



&&

.LONG TERM /SATURDAY THROUGH MONDAY/...
AS OF 200 PM MONDAY...THERE IS FAIRLY LOW CONFIDENCE IN THE MEDIUM
RANGE FORECAST WITH CONSIDERABLE SPREAD AMONG THE GFS ENSEMBLE
MEMBERS...AS WELL AS BETWEEN THE 12Z GFS AND THE 00Z ECMWF. THE GFS
REMAINS THE MORE PROGRESSIVE SOLUTION AS IT TAKES THE CLOSED UPPER
LOW NORTHEAST OF THE FA ON SATURDAY. ON THE OTHER HAND THE ECMWF
STALLS AND WEAKENS THE LOW OVER THE CAROLINAS...ALLOWING FOR DEEP
MOISTURE AND EASTERLY UPSLOPE ATLANTIC FLOW TO GENERATE PRECIP
THROUGH SUNDAY NIGHT. AT THIS POINT I WILL LEAN TOWARDS THE DRY GFS
SOLUTION AND WILL NOT INTRODUCE POPS INTO THE WEEKEND. THE RIDGE
CONTINUES TO BUILD AND TAKE CONTROL SUNDAY AND MONDAY ACROSS THE
SOUTHEAST SO WILL CONTINUE TO ADVERTISE TEMPS 3 TO 5 DEGREES ABOVE
NORMAL.

&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
A STRONG RIDGE OF DRY HIGH PRESSURE WILL ALLOW VFR CONDITIONS AND
LIGHT NORTHEAST FLOW TO CONTINUE THROUGH THE EVENING HOURS. A BACK
DOOR COLD FRONT WILL SLOWLY PUSH SOUTHWARD INTO THE TERMINAL
FORECAST AREA...BUT WITH DIMINISHING MOISTURE. UPSLOPE AND UPGLIDE
FLOW ALONG AND NORTH OF INTERSTATE 40 LATE TONIGHT SHOULD BRING THE
BEST CHANCE OF VFR CEILINGS TO KHKY AND KAVL...AND ANY CIGS THAT
DEVELOP MAY PERSIST THROUGH NOON TUESDAY BEFORE SCATTERING.

FOG REMAINS A POSSIBILITY TONIGHT WITH LITTLE AIRMASS CHANGE PRIOR
TO THE WEAK FRONTAL PASSAGE. HOWEVER...SREF AND LAMP PROBABILITIES
ARE NOT AS AGGRESSIVE AS THE MOS WITH LOWER VSBY
OVERNIGHT...ESPECIALLY AT KAVL...AND INCREASING CLOUD COVER FROM THE
NORTH COULD INHIBIT FOG POTENTIAL. WILL FEATURE A WINDOW OF MVFR
VSBY AT KHKY AFTER 09Z...IFR VSBY AT KAVL AFTER 08Z...AND ADVERTISE
NOTHING WORSE THAN 6SM AT PRESENT FOR THE REST OF THE
PIEDMONT/FOOTHILL TAF SITES.

WINDS WILL COME UP AT 7 TO 9 KT FROM THE ENE ON TUESDAY WITH
MIXING...AND SCT TO BKN VFR LEVEL STRATOCUMULUS SHOULD REMAIN IN THE
PICTURE THROUGH THE DAY...BUT WITH LITTLE PRECIPITATION CHANCE.

OUTLOOK...RAIN CHANCES WILL INCREASE RAPIDLY FROM THE WEST BY
WEDNESDAY AS A STRONG LOW PRESSURE SYSTEM APPROACHES FROM THE
PLAINS. MVFR CONDITIONS...WITH TEMPO IFR...WILL BE POSSIBLE
WEDNESDAY THROUGH THURSDAY...WITH GRADUAL CLEARING FRIDAY INTO
SATURDAY.

&&

.GSP WATCHES/WARNINGS/ADVISORIES...
GA...NONE.
NC...NONE.
SC...NONE.

&&

$$
SYNOPSIS...BSH
NEAR TERM...HG
SHORT TERM...LG
LONG TERM...BSH
AVIATION...HG



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