Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 260540
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1240 AM EST FRI DEC 26 2014

.SYNOPSIS...
HIGH PRESSURE WILL BE CENTERED OVER OUR AREA TODAY...PROVIDING
PLEASANT WEATHER WITH SLIGHTLY ABOVE NORMAL TEMPERATURES. EXPECT THE
NEXT COLD FRONT TO APPROACH FROM THE WEST THIS WEEKEND WITH LOW
PRESSURE RIDING UP ALONG THE FRONT. THE FRONT WILL CROSS THE AREA ON
MONDAY WITH COOLER HIGH PRESSURE BUILDING IN FROM THE WEST THROUGH
MID WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1230 AM EST...A CUTOFF LOW PRESSURE SYSTEM HAS DEVELOPED OVER
THE FOUR CORNERS REGION OF THE SOUTHWESTERN U.S. EARLY THIS MORNING.
DOWNSTREAM OF THIS FEATURE...BROAD RIDGING IS IN PLACE ALOFT OVER
SURFACE HIGH PRESSURE ACROSS THE SOUTHEAST. A FEW HIGH CLOUDS WILL
START ARRIVING OVER THIS SHALLOW RIDGE TODAY...BUT WITH LITTLE
IMPACT ON INSOLATION. WITH LIGHT SOUTHERLY FLOW IN MOST
AREAS...EXPECT MAXES TO REACH 5 TO 10 DEGREES ABOVE CLIMO...MAINLY
55 TO 60 DEGREES.

GENERALLY DRY PROFILES SHOULD REMAIN THROUGH TONIGHT...BUT WITH A
GRADUAL INCREASE IN MID TO HIGH LEVEL MOISTURE IN THE DEEP LAYER SW
FLOW. THE AIRMASS RECOVERY AND THE SLOWLY INCREASING CLOUDS MAY LEAD
TO MIN TEMPS REBOUNDING A CATEGORY OR TWO OVER FRI MORNING VALUES.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
AS OF 200 PM EST THURSDAY...LATEST SHORT RANGE MODELS AGREE THAT
592DM UPPER ANTICYCLONE WILL REMAIN ANCHORED SOUTH OF FL WHILE A
DEEP UPPER TROUGH OVER THE WESTERN CONUS FRI NIGHT WILL MOVE
EASTWARD...BECOMING POSITIVELY TILED AS IT REACHES THE MISSISSIPPI
VALLEY BY SUN. THIS UPPER PATTERN SHOULD ALLOW A MOIST SOUTHWESTERLY
FLOW ALOFT TO CONTINUE OVER THE REGION THRU THE PERIOD.

AT THE SURFACE...WE WILL SEE INCREASINGLY WAA SWLY FLOW FRI NIGHT
INTO SAT AS THE HIGH CENTERED OVER THE EASTERN CAROLINAS MIGRATES
OFFSHORE AND A COLD FRONT EXTENDING FROM THE WESTERN GREAT LAKES
REGION TO TX SLOWLY MOVES EASTWARD...REACHING THE MISSISSIPPI VALLEY
BY SAT AFTERNOON. LATEST MODELS HAVE TRENDED A BIT SLOWER WITH THE
ONSET OF PRECIP AS A WAVE OF SURFACE LOW OVER THE WESTERN GULF LIFTS
NORTHEAST ALONG THE FRONT...DRAWING A PLUME OF DEEP GULF MOISTURE
INTO THE UPPER SAVANNAH RIVER VALLEY AND THE EXTREME WESTERN NC MTNS
BY 00Z SUN. THEREFORE...POPS HAVE BEEN LOWERED ACCORDINGLY ON SAT
AFTERNOON/EVENING...HIGHLIGHTING A SLIGHT CHANCE TO LOW END CHANCE
RANGE OVER THE WESTERN HALF OF THE CWA.

SAT NIGHT AND SUN...THE FRONT WILL CONTINUE TO MOVE EASTWARD
SLOWLY...REACHING THE SOUTHERN APPALACHIANS BY 18Z SUN WITH A WAVE
OF LOW PRESSURE ALONG THE FRONT LIFTING NE ACROSS THE TN VALLEY AND
THE NC MTNS AT THE SAME TIME. THEREFORE...POPS QUICKLY RAMP UP INTO
THE LIKELY RANGE OVER MUCH OF THE REGION WITH CATEGORICAL POPS
OVER THE WESTERN NC MTNS SAT NIGHT THROUGH SUN. USING A MODEL
BLEND...TOTAL RAINFALL WILL BE AROUND 0.1-0.25" ACROSS MUCH OF THE
CWA WITH UP TO 0.5" OVER THE HIGHER ELEVATIONS OF THE WESTERN MTNS.
WITH PREVAILING WAA FLOW...FROZEN PRECIP IS NOT EXPECTED ATT. HAVE
MENTIONED A CHANCE OF AFTERNOON THUNDER...MAINLY OVER NE
GA...WESTERN UPSTATE SC..AND PORTIONS OF THE WESTERN NC MTNS ZONES
AS SOME DEGREE OF MUCAPE WILL BE PRESENT. TEMPERATURES WILL REMAIN
7-10 DEGREES ABOVE NORMAL THROUGH THE PERIOD.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
AS OF 215 PM THURSDAY...THERE IS STILL SOME DISAGREEMENT ON THE
TIMING AND AMPLITUDE OF SOUTHERN STREAM SHORTWAVE ENERGY SUNDAY
NIGHT THRU MONDAY. THE 12Z ECMWF/CMC ARE SLOWER AND STRONGER WITH A
SFC WAVE TRACKING ACRS THE SOUTHEAST STATES. UP UNTIL THOSE
SOLNS...THE MODELS SEEMED TO BE CONVERGING ON A MORE
PROGRESSIVE/SHALLOWER SYSTEM. I WILL CONTINUE TO GRADUALLY TAPER
POPS FROM SUNDAY NIGHT THRU MONDAY NIGHT...GIVEN THE UNCERTAINTY.
THIS WILL ALSO HAVE AN IMPACT ON TEMPS...AS A BACKDOOR COLD FRONT
SHUD PUSH THRU ON MONDAY. TEMPS WILL BE WELL ABOVE NORMAL AHEAD OF
THE FRONT...THEN CLOSE TO NORMAL BY TUESDAY BEHIND THE FRONT. THE
MODELS HAVE TRENDED FURTHER SOUTH WITH THE SFC FRONT FOR
MIDWEEK...ALLOWING A LARGE ARCTIC HIGH TO SPRAWL ACRS THE PLAINS TO
THE APPALACHIANS. I WILL TAKE OUT THE POP FOR LATE TUESDAY THRU
WEDNESDAY NIGHT. TEMPS WILL LIKELY BE SLIGHTLY BELOW NORMAL.
HOWEVER...DEPENDING ON ANY LINGERING CLOUD COVER (AS HINTED BY 850
MB RH)...MIN TEMPS MAY REMAIN ABOVE NORMAL.

UNCERTAINTY REALLY INCREASES BY THURSDAY...AS A CUTOFF LOW INVOF
CALIFORNIA IS EXPECTED TO EJECT AND TRACK THRU THE SOUTHERN STREAM
LATE NEXT WEEK. IT WOULD SEEM A SLOWER SOLN IS MORE LIKELY...GIVEN
THE BLOCKY PATTERN ACRS THE ERN PACIFIC AND THE WEST COAST. THE 12Z
ECWMF IS STILL ON THE EARLIER SIDE OF GUIDANCE WITH THE
SHORTWAVE...BREWING A SRN STREAM SYSTEM INVOF THE TX COAST BY
THURSDAY. INTERESTINGLY...THE 12Z GEFS HAS A BRIEF UPGLIDE EVENT
AHEAD OF THE SHORTWAVE FOR WED NGT AND THURSDAY ATOP A DOME OF
ARCTIC AIR ACRS THE SOUTHEAST STATES. THIS WOULD LIKELY RESULT IN A
WINTRY MIX OF PRECIP. THE GFS AND ECMWF DO NOT SHOW THIS...AND ONCE
MOISTURE DOES ARRIVE IN THEIR SOLNS...THE LLVLS WARM TO MAINLY A
RAIN EVENT. AGAIN...CONFIDENCE IN TIMING IN VERY LOW...AND THE
MOISTURE MAY NOT ARRIVE UNTIL BEYOND 12Z FRIDAY. I WILL BEGIN TO
INTRODUCE SLGT CHC TO LOW-END CHC POP FOR LATE THURSDAY.

&&

.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
AT KCLT AND ELSEWHERE...DRY HIGH PRESSURE WILL REMAIN OVER THE
TERMINAL FORECAST AREA THROUGH THE PERIOD. FEW TO SCATTERED HIGH
CLOUDS ARE EXPECTED IN THE DEEP SWLY FLOW OVER THE RIDGE. ANTICIPATE
CALM WINDS THROUGHOUT THIS MORNING...WITH LIGHT SRLY FLOW DEVELOPING
WITH MIXING BY LATE MORNING...EXCEPT LIGHT NW FLOW IN THE FRENCH
BROAD VALLEY AT KAVL.

OUTLOOK...VFR CONDITIONS CONTINUE THROUGH LATE SATURDAY. MOISTURE
WILL RETURN AHEAD OF THE NEXT COLD FRONT SATURDAY NIGHT...WHICH
COULD BRING FLIGHT RESTRICTIONS BACK ON SUNDAY. SOME IMPROVEMENT IS
EXPECTED ON MONDAY...WITH THE NEXT APPROACHING COLD FRONT ARRIVING
BY WEDNESDAY.

CONFIDENCE TABLE...

            06-12Z        12-18Z        18-24Z        00-06Z
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 SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES AND ENSEMBLE FORECASTS
ARE AVAILABLE AT THE FOLLOWING LINK: (MUST BE LOWER CASE)

WWW.WEATHER.GOV/GSP/AVIATION_TABLES

&&

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

&&

$$
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...JOH
LONG TERM...ARK
AVIATION...HG



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