Area Forecast Discussion
Issued by NWS Greer, SC

Home | Current Version | Previous Version | Text Only | Print | Product List | Glossary On
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50
000
FXUS62 KGSP 262155
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
455 PM EST FRI DEC 26 2014

.SYNOPSIS...
HIGH PRESSURE WILL MOVE OFF THE CAROLINA COAST TONIGHT AND
SATURDAY AS A COLD FRONT APPROACHES FROM THE WEST.  EXPECT
TEMPERATURES TO BE A FEW DEGREES ABOVE NORMAL THIS WEEKEND.  THE
FRONT WILL CROSS MONDAY WITH A SECONDARY FRONT PASSING IN MID WEEK
DROPPING TEMPERATURES TO BELOW NORMAL. THE NEXT COLD FRONT WILL
ARRIVE AT THE END OF NEXT WEEK.

&&

.NEAR TERM /THROUGH SATURDAY/...
AS OF 450 PM...LATEST SATELLITE IMAGES INDICATED A FEW PATCHES OF
HIGH CLOUDS DRIFTING ACROSS THE WESTERN CAROLINAS LATE THIS
AFTERNOON. I WILL UPDATE THE FORECAST TO ALIGN HOURLY TEMP/DWPTS TO
OBSERVATIONS AND ADJUST SKY COVER. OTHERWISE...THE CURRENT FORECAST
REMAINS ON TRACK.

AS OF 200 PM EST FRIDAY...DEEP MOISTURE ASSOCIATED WITH A WEAK UPPER
DISTURBANCE CURRENTLY OVER THE NORTHERN AL/TN IS EXPECTED TO LIFT
NEWARD...PASSING WEST OF THE SOUTHERN APPALACHIANS THROUGH TONIGHT.
THIS WILL BRING CONSIDERABLE HIGH CLOUDS TO THE WESTERN MTNS ZONES
THROUGH THE EVENING HOURS. OTHERWISE...WE WILL SEE CONTINUED DRY
WEATHER WITH MOSTLY CLEAR SKIES AS AN UPPER RIDGE CONTINUES TO
AMPLIFY ACROSS THE SOUTHEAST STATES AND A SURFACE HIGH REMAINS IN
PLACE. WITH INCREASING THICKNESSES AND PREVAILING WEAK SOUTHERLY
WINDS...MORNING LOW TEMPS ON SAT WILL BE AROUND 2-3 DEGREES WARMER
THAN THIS MORNING/S LOW.

SAT...MOIST SWLY FLOW DEVELOPS ACROSS THE AREA AS THE UPPER RIDGE
AXIS MOVES OFFSHORE AND AN UPPER TROUGH MOVES EAST ACROSS THE
ROCKIES. THIS WILL ALLOW SURFACE HIGH TO MIGRATE OFF THE EAST COAST
AND A SURFACE COLD FRONT TO MOVE EASTWARD INTO THE MISSISSIPPI
VALLEY  THROUGH SAT AFTERNOON. LATEST MODELS CONTINUE TO SUGGEST
THAT A WAVE OF LOW WILL DEVELOP OVER THE WESTERN GULF AND LIFT NE
ALONG THE FRONT THRU SAT EVENING. THIS WILL DRAW A DEEP PLUME OF
GULF MOISTURE INTO THE SOUTHEAST. HOWEVER...MODELS HAVE TRENDED A
BIT SLOWER WITH THE ONSET OF PRECIP...KEEPING OUR CWA DRY UNTIL 00Z
SUN. HENCE...HAVE GONE WITH DRY FORECAST THRU SAT EVENING. PARTLY
CLOUDY SKIES SAT MORNING WILL GIVE WAY TO MOSTLY CLOUDY BY SAT
EVENING IN LIGHT OF INCREASING MOISTURE. AFTERNOON TEMPS WILL STAY
7-10 DEGREES ABOVE CLIMO FOR MOST LOCATIONS.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY NIGHT/...
AS OF 230 PM FRI...HOPE YOU MADE THE MOST OF THE SUNSHINE TODAY AND
WILL MAKE THE BEST OF IT ON SATURDAY...BECAUSE IT LOOKS LIKE WE ARE
IN FOR ANOTHER PERIOD OF CLOUDY AND WET WEATHER STARTING SATURDAY
NIGHT. THE MODELS ARE IN GOOD AGREEMENT WITH SPREADING FORCING AND
DEEP MOISTURE INTO THE REGION FROM THE SOUTHWEST STARTING ON
SATURDAY EVENING. THAT SAID...THE MODELS ALSO INDICATE A DELAY WITH
THE ONSET OF THE PRECIP RELATIVE TO THE OLD FORECAST. SOME MID LEVEL
FORCING SHOULD ARRIVE VERY LATE IN THE DAY...AS A LEAD WAVE COMES UP
FROM THE SW AND MID LEVEL ISENTROPIC UPGLIDE COMMENCES...BUT THAT
WILL PROBABLY NOT BE ENOUGH TO GET THE PRECIP DOWN TO THE GROUND
UNTIL AFTER 00Z SUNDAY WITH AN EXPECTED DRY SUBCLOUD LAYER TO
OVERCOME. SO...THE TIMING OF ONSET HAS BEEN NARROWED TO INDICATE A
DELAY THEN MORE RAPID RAMP UP OF HIGH PRECIP PROBABILITY...
ESPECIALLY OVER THE WRN PIEDMONT OF NC. THE NEW FCST EVENTUALLY
CATHES UP TO THE OLD FCST BY SUNRISE ON SUNDAY WITH A CATEGORICAL
POP OVER THE WEST AND A LIKELY POP OVER THE EAST. FROM THAT POINT
ONWARD...THE MODELS KEEP DEEP MOISTURE AND SOME MANNER OF FORCING
OVER THE REGION INTO MONDAY...BE IT UPPER DIVERGENCE SUNDAY
MORNING...MID LEVEL DPVA SUNDAY AND SUNDAY NIGHT...OR MOIST UPGLIDE
THROUGHOUT THAT PERIOD. THE FCST KEEPS A FAIRLY HIGH POP...FAVORING
THE MTNS A BIT THROUGH SUNDAY NIGHT. THE PASSAGE OF THE MAIN SHORT
WAVE AXIS EARLY MONDAY SHOULD BRING AN END TO THE BETTER CHANCES OF
PRECIP. FROM THAT POINT ONWARD...A SLOW DECREASE IN COVERAGE ON
MONDAY. WE SHOULD DRY OUT BY SUNRISE ON TUESDAY. FORTUNATELY...TEMPS
WILL REMAIN ABOVE FREEZING THROUGH THE WHOLE PERIOD...SO NO PRECIP
TYPE ISSUES ARE EXPECTED AT THIS TIME. UNLIKE PREVIOUS EVENTS...THE
CENTER OF HIGH PRESSURE TO OUR EAST CLOSER TO BERMUDA SHOULD ALLOW
US TO REMAIN UN-WEDGED. EVEN MORE FORTUNATELY...THE MODELS FAIL TO
DEVELOP ANY INSTABILITY ACROSS THE REGION...SO SEVERE WEATHER
CHANCES LOOK VERY LOW IN SPITE OF BEING FREE FROM COLD AIR DAMMING.

&&

.LONG TERM /TUESDAY THROUGH FRIDAY/...
AS OF 215 PM FRIDAY...MODELS ARE COMING INTO A LITTLE BETTER
AGREEMENT ON THE MEDIUM RANGE FORECAST. TUESDAY THRU THURSDAY STILL
LOOKS DRY AND SEASONABLY COOL...AS A LARGE MODIFYING ARCTIC AIR MASS
SETTLES ACRS THE MID SECTION OF THE COUNTRY UNDER CONFLUENT SPLIT
FLOW ALOFT. A CUTOFF LOW INVOF CALIFORNIA WILL EVENTUALLY GET KICKED
OUT INTO THE SOUTHERN STREAM...AT SOME POINT LATE NEXT WEEK. MODELS
CONTINUE TO DELAY THE TIMING OF THIS SHORTWAVE TROF. USING THE
LATEST CONSENSUS...I HAVE DELAYED POPS RETURNING UNTIL FRIDAY
MORNING. WITH A COLD AIR MASS STILL IN PLACE WHEN THE MOISTURE FIRST
STARTS ADVECTING BACK IN FROM THE SOUTHWEST...THERE MAY BE SOME P-
TYPE CONCERNS. HOWEVER...THERE IS STILL A LOT OF UNCERTAINTY ON THE
EXACT TIMING. ALSO...REGARDLESS OF THE MODEL SOLN...IT DOES LOOK
LIKE LLVL THICKNESSES WILL INCREASE AS PRECIP MOVES IN...SUCH THAT
PRECIP SHUD CHANGE OVER TO ALL RAIN. BOTH THE GFS AND ECMWF HAVE
ONLY A WEAK IN SITU COLD AIR DAMMING WEDGE ACRS THE CWFA BY FRIDAY
NIGHT. HIGH TEMPS WILL CONTINUE TO BE SLIGHTLY BELOW NORMAL THRU
FRIDAY...WITH NEAR TO SLIGHTLY ABOVE NORMAL LOWS.

&&

.AVIATION /22Z FRIDAY THROUGH WEDNESDAY/...
AT KCLT AND ELSEWHERE...DRY HIGH PRESSURE WILL CONTINUE TO DOMINATE
OUR WEATHER...YIELDING VFR CONDITIONS THRU 18Z SAT. WITH MOIST SWLY
FLOW ALOFT SETTING UP...HIGH CLOUDS WILL OVERSPREAD THE AREA THIS
EVENING INTO SAT. LIGHT S/SSW WINDS WILL CONTINUE FOR MOST LOCATIONS
THRU THE TAF PERIOD...WITH THE EXCEPTION OF KAVL WHERE WINDS WILL
VEER TO THE NORTH BY THIS EVENING.

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

CONFIDENCE TABLE...

            22-04Z        04-10Z        10-16Z        16-18Z
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...NED/JOH
SHORT TERM...PM
LONG TERM...ARK
AVIATION...JOH


USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.