FXUS62 KGSP 050907
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
407 AM EST SUN FEB 5 2012

.SYNOPSIS...
AN UPPER LEVEL LOW WITH A COLD FRONT WILL MOVE THROUGH THE REGION
BRINGING UNSETTLED WEATHER TODAY. SURFACE HIGH WILL BUILD BEHIND THE
FRONT FOR MOSTLY DRY WEATHER THROUGH FRIDAY. ANOTHER COLD FRONT WILL
INFLUENCE OUR WEATHER IN THE WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AT 2 AM EST SUNDAY...A BACK DOOR COLD FRONT WAS LOCATED NEAR THE
INTERSTATE 40 CORRIDOR IN NC...WHILE AN EASTWARD MOVING COLD FRONT
WAS LOCATED IN THE GULF STATES. A WEAK UPPER SHORTWAVE WILL DEPART
OUR AREA TO THE EAST BY DAYBREAK. A POSITIVELY TILTED UPPER TROUGH
WILL DROP SOUTH ACROSS THE OH VALLEY TODAY...DRIVING THE BACK DOOR
FRONT SOUTH ACROSS OUR AREA. ISENTROPIC UPGLIDE AHEAD OF THE FRONT
WILL DECREASE...LEADING TO LESS PRECIPITATION COVERAGE. THE COLD
FRONT OVER THE GULF STATES IS EXPECTED TO PASS WELL SOUTH OF OUR
AREA. BETWEEN LINGERING CLOUD COVER...AND THE ARRIVAL OF COOL NE
FLOW...MAXIMUM TEMPERATURES ARE EXPECTED TO BE CLOSER TO THE COOLER
MET GUIDANCE THAN THE WARMER MAV...AT LEAST IN NC. THE WARMEST AREA
IS EXPECTED TO BE UPSTATE SC AND NE GA....WHERE THE MET CONURS WITH
THE MAV...AND FROTNAL PASSAGE IS NOT UNTIL MID AFTERNOON.

WITH LITTLE FORCING REMAINING IN THE WAKE OF THE FRONT...POPS WILL
BE ALLOWED TO FALL OFF TO SLIGHT CHANCE TONIGHT. GUIDANCE TAKES
TEMPERATURES DOWN TO NEAR FREEZING IN THE HIGHER MOUNTAINS...BUT
MODEL SOUNDINGS ARE NOT MOIST ENOUGH AT ICE NUCLEATION TEMPERATURES
TO SUPPORT SNOW. AT MOST SOME FREEZING DRIZZLE OR RIME ICING APPEARS
POSSIBLE ON SOME MOUNTAIN TOPS...BUT WITH THE GROUND RELATIVELY
WARM...ACCUMULATIONS SHOULD BE ON ELEVATED SURFACES...AND QUITE
LIGHT AT THAT.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 2 AM SUNDAY...THE SHORT TERM FORECAST STARTS WITH THE
SHORTWAVE PASSING FROM TN TO NC DURING THE DAY ON MONDAY. THERE IS
AGREEMENT IN THE GFS AND ECMWF IN THIS BEING A STRONG CLOSED OFF
500MB LOW WHILE THE NAM AND SREF HAVE A MUCH WEAKER SHORTWAVE AND
FAR FROM BEING CLOSED OFF. CONSENSUS IS FOR THIS TO MAINTAIN
CLOUDINESS ACROSS THE WESTERN CAROLINAS THROUGH MUCH OF THE DAY WITH
SOME LIGHT RAIN KEEPING TEMPS FROM RISING MUCH. MAXES ARE EXPECTED
TO BE CLOSE TO NORMAL ON MONDAY. THERE ARE TIMING DIFFERENCES AS TO
WHEN THE WAVE WILL MOVE EAST OF THE INTERSTATE 77 CORRIDOR. LATE IN
THE DAY TOWARD SUNSET SEEMS ABOUT RIGHT. BEHIND THIS...DRIER AIR
MOVES IN MONDAY NIGHT THROUGH TUESDAY. BRIEF ZONAL FLOW IN THIS
PERIOD WITH PLENTY OF SUNSHINE ON TUESDAY TAKING MAX TEMPS A FEW
DEGREES ABOVE NORMAL. CLOUDINESS BEGINS TO INCREASE AGAIN TUESDAY
EVENING AHEAD OF THE NEXT SHORTWAVE CROSSING THE MISS VALLEY. THE
LATEST GFS CREATES SOME LIGHT PRECIP ACROSS THE NC MOUNTAINS TUESDAY
NIGHT...BUT THAT IS THE ONLY MODEL WITH ANY LIFT CAPABLE OF
PRODUCING PRECIP. THE BRAND NEW ECMWF HOLDS OFF IN BRINGING THE
SHORTWAVE AND THUS ANY PRECIP TO THE NC MOUNTAINS UNTIL WED
AFTERNOON.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 230 AM EST SUNDAY...THE MEDIUM RANGE FORECAST WILL BE ANOTHER
LOW CONFIDENCE ONE AS THE LATEST 00Z OPERATIONAL MODEL RUNS CONTINUE
TO SHOW QUITE A BIT OF SPREAD. THE ECMWF HAS A WEAK UPPER LEVEL LOW
OVER TN/KY BRINGING LIGHT PCPN TO MAINLY OVER THE NC MOUNTAINS LATE
WED INTO THU WHILE THE GFS HAS A BROAD CONTINENTAL HIGH PRESSURE
COVERING THE EASTERN STATES DURING THE PERIOD. IF THE ECMWF PANS
OUT...THERE COULD BE SOME LIGHT SNOW SHOWERS OVER THE NC MTNS WED
NIGHT WITH COLDER TEMPS. HOWEVER...I KEPT DRY WEATHER WITH MOSTLY
CLOUDY IN THE GRIDS DUE TO THE UNCERTAINTY. THEN THE ECMWF HAS A
RATHER PROLONGED DRY CONDITIONS THROUGHOUT THE REMAINDER OF THE
MEDIUM RANGE PERIOD AS BROAD SURFACE HIGH DOMINATES THE EASTERN
STATES. THE GFS ON THE OTHER HAND...BRINGS DECENT MOISTURE TO OUR
CWFA LATE SAT INTO SUN MORNING AS A CLIPPER SYSTEM SWEEPING ACROSS
OUR REGION IN THE WAKE OF A DEEPENING UPPER LOW PRESSURE TROUGH OVER
THE GREAT LAKES. HOWEVER...WILL KEEP FCST DRY AGAIN DUE TO THE
UNCERTAINTY. TEMPERATURES WILL REMAIN NEAR SEASONAL AVERAGES THROUGH
SATURDAY, BEFORE DROPPING A FEW DEGREES BELOW THE NORMALS ON SUNDAY.

&&

.AVIATION /09Z SUNDAY THROUGH THURSDAY/...
AT KCLT...A GUIDANCE BLEND SUPPORTS LIFR CIG TOWARD DAWN...WITH MVFR
VSBY IN RAIN AND FOG. CIG TRANSITIONS TO MVFR THIS MORNING AS A BACK
DOOR COLD FRONT MOVES IN FROM THE NE...WHILE VSBY IMPROVES TO IFR
AND WINDS PICK UP FROM NE. IFR CIG RETURNS THIS EVENING IN COOL
MOIST AIR MASS NORTH OF THE FRONT.

KAVL...GUIDANCE BLEND SUGGESTS MVFR CIG THAT BECOMES IFR BRIEFLY AT
DAWN...THE RISES TO BECOME BRIEFLY VFR IN THE AFTERNOON...THEN BACK
TO IFR THIS EVENING. MVFR VSBY BEFORE DAWN IN RAIN. WINDS BECOME NNW
BY DAYBREAK AND STAY THERE.

ELSEWHERE...BLENDED GUIDANCE BRINGS IN MVFR CIGS OVERNIGHT...EXCEPT
BRIEFLY IFR AT KHKY AROUND DAYBREAK. CIGS BECOME VFR AT SC SITES
DURING THE DAY...THEN RETURN TO MVFR BEHIND A BACK DOOR COLD FRONT
THIS EVENING. MVFR VSBY RESTRICTIONS IN RAIN AND FOG BEFORE DAWN.
WINDS VEER FROM SW TO NE TODAY AS BACK DOOR FRONT ARRIVES FROM N.

OUTLOOK...DRY HIGH PRESSURE IS FORECAST TO BUILD ACROSS THE REGION
ON MONDAY. DRY AIR IS EXPECTED TO REMAIN THROUGH MOST OF THE WORK
WEEK.

AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE
PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE
CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)...

WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM

&&

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

&&

$$
SYNOPSIS...JOH
NEAR TERM...JAT
SHORT TERM...DEO
LONG TERM...JOH
AVIATION...JAT



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