Area Forecast Discussion
Issued by NWS Greer, SC

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270
FXUS62 KGSP 111704
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1204 PM EST THU FEB 11 2016

.SYNOPSIS...
HIGH PRESSURE WILL MOVE ACROSS THE REGION TODAY AND TONIGHT. A
FAST-MOVING UPPER DISTURBANCE WILL BRING A BRIEF CHANCE OF
PRECIPITATION TO PARTS OF THE AREA FRIDAY. A STRONGER DOME OF
CANADIAN HIGH PRESSURE WILL SETTLE IN FOR THE WEEKEND...USHERING
IN ANOTHER PERIOD OF COLD TEMPERATURES. THIS WILL BE FOLLOWED
BY ANOTHER WEATHER SYSTEM WHICH WILL PRODUCE A BETTER CHANCE OF
PRECIPITATION EARLY NEXT WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
1715 UTC UPDATE...SKY COVER HAS BEEN ADJUSTED AGAIN PER VISIBLE
SATELLITE IMAGERY...ACCOUNTING FOR A BAND OF CLOUDS OVER THE SC
UPSTATE. WINDS WERE UPDATED WITH A BLEND OF THE LATEST NAM AND
ADJMAV.

1500 UTC UPDATE...SKY COVER WAS ADJUSTED PER INFRARED SATELLITE
IMAGERY...RESULTING IN A DECREASE EAST OF THE MOUNTAINS. WINDS WERE
UPDATED FROM A BLEND OF THE LATEST NAM AND ADJMAV...WITH ONLY A
SLIGHT DECREASE NOTED. MAXIMUM TEMPERATURES WERE LOWERED SLIGHTLY
BASED ON A MODEL BLEND. SNOWFALL ON THE TN BORDER WILL BE ALLOWED
TO DECREASE THIS MORNING PER RADAR TRENDS.

AS OF 615 AM...A RELATIVELY TIGHT UPPER HEIGHT GRADIENT PERSISTS
OVER THE CWFA TODAY...WITH UPPER TROUGH AXIS OVER THE ATLANTIC
COAST. NORTHWEST FLOW INTO THE APPALACHIANS WILL CONTINUE...BUT
WILL GRADUALLY WEAKEN IN RESPONSE TO WEAKENING GRADIENT BEHIND THE
DEPARTING TROUGH. BAND OF CLOUD COVER OVER KY/TN HAS SHIFTED NEWD
AS EXPECTED...AND WILL PROVIDE A CONTINUED SOURCE OF MOISTURE FOR
LIGHT SNOW SHOWERS IN THE UPSLOPE AREAS THRU THE FIRST HALF OF THE
DAY. PER RADAR MOSAIC...MOST PRONOUNCED BAND CURRENTLY POINTED
INTO MADISON CO IS SET TO SHIFT TOWARD THE NORTH...SO A BURST
OF SNOW IS EXPECTED IN THE NRN MTNS BEFORE THE SHOWERS FINALLY
TAPER OFF AT MIDDAY. THE DOWNSLOPE FLOW...RISING THICKNESSES...AND
PARTLY TO MOSTLY SUNNY SKIES WILL BRING MAX TEMPS UP A COUPLE OF
CATEGORIES FROM WEDNESDAY/S VALUES. THAT WILL STILL BE ABOUT 10
DEGREES BELOW CLIMO.

HEIGHTS RISE INTO THIS EVENING AS BROAD HIGH PRESSURE MOVES OUT OF
THE MID-MISSISSIPPI VALLEY...CENTERING OVER THE TIDEWATER REGION
BY EARLY FRI. HOWEVER...QUICKLY COMING IN THE WAKE OF THE HIGH IS A
WEAK SHORTWAVE PROGGED TO REACH THE OHIO VALLEY BY DAYBREAK. BACKING
LOW TO MIDLEVEL FLOW DOWNSTREAM OF THIS WAVE RESULTS IN SLIGHT
ISENTROPIC LIFT ACROSS OUR AREA IN THE WEE HRS OF THE MRNG. MOISTURE
IS MARGINAL...BUT IS DEEPEST OVER THE NRN HALF OF THE CWFA...SO I
WILL INTRODUCE A LOW POP THERE BEFORE 12Z. PTYPE EXPECTED TO BE ALL
SNOW...WITH WARM ADVECTION NOT HAVING OCCURRED LONG ENOUGH TO CREATE
A WARM NOSE IN PROFILES OVER THIS AREA. MINS WILL REMAIN SEVERAL
DEGREES BELOW NORMAL. NO WIND CHILL ISSUES ARE EXPECTED...WITH
LOWEST VALUES ALMOST ENTIRELY ABOVE ZERO EVEN ON RIDGES.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY NIGHT/...
AS OF 220 AM THURSDAY...A SHORT WAVE DIVING INTO THE EAST COAST
TROUGH CROSSES THE AREA FRIDAY. A WEAK SURFACE WAVE FORMING NEAR THE
GA/SC COAST AND MOVING NORTH ALONG THE COAST IN RESPONSE. THE
GUIDANCE IS IN GOOD AGREEMENT THAT THERE WILL BE CLOUDS FORMING
OUTSIDE OF THE MOUNTAINS...ALONG WITH SOME FLURRIES OR SPRINKLES
OVER NC AND THE EASTERN UPSTATE. DO NOT EXPECT ANY ACCUMULATIONS
BUT CANNOT RULE OUT SOME BRIEFLY HEAVIER THAN FLURRY OR SPRINKLE
PRECIP. EXPECT ANOTHER ROUND OF NW FLOW SNOWFALL ACROSS THE
MOUNTAINS WITH GOOD LOW LEVEL MOISTURE...COLD ADVECTION AND
STRENGTHENING NW FLOW. EXPECT GENERALLY LIGHT ACCUMS IN THE USUAL
HIGH ELEVATION AREAS NEAR THE TN BORDER...BUT CANNOT RULE OUT A
COUPLE OF INCHES BY THE TIME SNOW ENDS LATE FRIDAY NIGHT OR EARLY
SATURDAY MORNING.

EXPECT VERY COLD AND DRY CONDITIONS TO DEVELOP SATURDAY AND SATURDAY
NIGHT AS A SPRAWLING 1040+ ARCTIC HIGH PRESSURE BUILDS INTO THE
REGION. HIGHS SATURDAY AND LOWS SATURDAY NIGHT WILL BE 15-20 DEGREES
BELOW NORMAL. ADVISORY LEVEL WIND CHILL VALUES WILL BE POSSIBLE
ACROSS THE MTNS...ALONG WITH THE POTENTIAL FOR A COLD WAVE.

&&

.LONG TERM /MONDAY THROUGH WEDNESDAY/...
AS OF 405 AM THURSDAY...GUIDANCE COMING INTO BETTER AGREEMENT
REGARDING THE FORECAST OF THE STORM SYSTEM MONDAY AND TUESDAY.

BUT FIRST...SUNDAY WILL BE COLD AND DRY AS ARCTIC HIGH PRESSURE
SETTLES IN OVER THE AREA. HIGHS WILL BE NEAR THE NORMAL LOWS FOR THE
DAY WITH VERY COLD WIND CHILL VALUES ACROSS THE MOUNTAINS IN THE
MORNING.

THE GUIDANCE IS TRENDING TOWARD A MILLER A TYPE SYSTEM...BUT THE
SURFACE LOW IS WELL INLAND WITH AN I-20 TO I-95 TRACK. MOISTURE
SPREADS INTO THE AREA LATE SUNDAY NIGHT AND REMAINS OVER THE AREA
MONDAY AND MONDAY NIGHT AS THE HIGH MOVES EAST ALONG THE AFORE
MENTIONED TRACK. WITH THE VERY COLD AIR IN PLACE AT PRECIP ONSET...
P-TYPE SHOULD START OUT AS SNOW. A WARM NOSE DEVELOPS AS LOW LEVEL
WARM ADVECTION TAKES PLACE MONDAY AS THE LOW MOVES SOUTH OF THE
AREA. THIS WILL CHANGE THE SNOW TO RAIN SOUTH OF I-85...AND PORTIONS
OF THE SW NC MOUNTAINS. THAT SAID...THE SURFACE TEMPS COULD REMAIN
NEAR OR BELOW FREEZING NORTH OF I-85 AND THE WARM NOSE COULD BE
STRONGER AND FARTHER NORTH. THIS WOULD MEAN A TRANSITION TO SLEET
AND FREEZING RAIN...CHANGING MAINLY TO RAIN SOUTH OF I-85. QPF COULD
BE QUITE HIGH CREATING THE POTENTIAL FOR SIGNIFICANT ACCUMULATIONS
OF A WINTRY MIX BEFORE PRECIPITATION TAPERS OFF TUESDAY AS DRIER AIR
MOVES IN BEHIND THE DEPARTING LOW PRESSURE SYSTEM. WILL KEEP THE HWO
MENTION...BUT UNCERTAINTY REMAINS AND THE FORECAST COULD CHANGE
SIGNIFICANTLY AS THE EVENT APPROACHES.

THE REST OF THE MEDIUM RANGE LOOKS RELATIVELY BENIGN. THERE WILL
LIKELY BE A PERIOD OF NW FLOW SNOW ON THE BACK SIDE OF THE SYSTEM
TUESDAY AND TUESDAY NIGHT...TAPERING OFF WEDNESDAY. HIGHS WILL WARM
BACK TO NORMAL LEVELS AS SEASONAL HIGH PRESSURE BUILDS IN.

&&

.AVIATION /17Z THURSDAY THROUGH MONDAY/...
AT KCLT...A LOW VFR CIG WILL SPREAD INTO THE AREA LATE TONIGHT...
FALLING TO IFR BY MID FRIDAY MORNING...AS LOW LEVEL MOISTURE
INCREASES. WINDS ARE EXPECTED TO VEER FROM WSW TO NW THIS
AFTERNOON...THEN TO NE TONIGHT. SNOW SHOWERS ARE EXPECTED TO REACH
THE AREA BY DAWN...PERSISTING THROUGH MIDDAY...BUT AT THIS POINT THE
CHANCES IS QUITE LOW...AND VSBY RESTRICTIONS WILL NOT BE CARRIED AT
THIS TIME.

ELSEWHERE...HIGH CIGS WILL ARRIVE THIS EVENING...FOLLOWED BY LOW VFR
CIGS AFTER MIDNIGHT...AS LOW LEVEL MOISTURE INCREASES. BY MID
MORNING IFR CIGS ARE EXPECTED AT SC SITES. FOOTHILL WINDS WILL VEER
FROM SW TO NE THIS EVENING...WHILE KAVL WINDS VEER FROM NW TO SE
OVERNIGHT AN BACK TO NW AFTER DAWN. SNOW SHOWERS ARE EXPECTED TO
REACH NC SITES BEFORE DAWN...BUT CHANCES ARE RATHER LOW...AND VSBY
RESTRICTIONS WILL NOT BE CARRIED AT THIS TIME. SNOW CANNOT TOTALLY
BE RULED OUT AT SC SITES...BUT IS NOT IN THE FORECAST AT THIS TIME.

OUTLOOK...LOW VFR OT IFR CEILINGS ARE POSSIBLE ON FRIDAY...AS AN
UPPER LOW MOVES UP THE CAROLINA COAST. AN ARCTIC AIR MASS WILL BUILD
OVER THE REGION THIS WEEKEND...WITH UPSLOPE CLOUDS ON THE WEST SIDE
OF THE APPALACHIANS. A SIGNIFICANT WINTER WEATHER SYSTEM IS POSSIBLE
EARLY NEXT WEEK.

CONFIDENCE TABLE...

            17-23Z        23-05Z        05-11Z        11-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KGMU       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAND       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%

THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULE TAF ISSUANCE FLIGHT RULE CATEGORY.  COMPLET HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK:

WWW.WEATHER.GOV/GSP/AVIATION

&&

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

&&

$$
SYNOPSIS...WIMBERLEY
NEAR TERM...JAT/WIMBERLEY
SHORT TERM...RWH
LONG TERM...RWH
AVIATION...JAT



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