Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 050512
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1212 AM EST THU MAR 5 2015

.SYNOPSIS...
A SLOW MOVING COLD FRONT WILL CROSS THE REGION FROM THE NORTHWEST
THROUGH THURSDAY.  COOL AND DRY HIGH PRESSURE RETURNS FOR
FRIDAY...THEN A SIGNIFICANT WARM UP OVER THE WEEKEND.  EXPECT A
COUPLE OF LOW PRESSURES TO COME OUT OF THE GULF NEXT WEEK.

&&

.NEAR TERM /THROUGH TODAY/...
AS OF 945 PM...FIRST BATCH OF SHOWERS MOVING INTO THE MTNS NEARLY ON
SCHEDULE...WITH LARGER AREA OF RAIN STILL OFF TO THE WEST. THIS WILL
MOVE IN AFTER MIDNIGHT. THEREFORE...EXPECT MORE SCT SHOWERS BEFORE
MIDNIGHT WITH WIDESPREAD RAIN SLOWLY MOVING IN AFTER. TEMPS ARE
STILL RUNNING QUITE WARM AS THE COLD AIR MASS REMAINS OFF TO THE NW.
LOOKS EVEN MORE LIKELY THAT ANY WINTRY PRECIP WILL HOLD OFF UNTIL AT
LEAST DAYBREAK WHEN THE COLDER AIR STARTS TO FILTER IN. HAVE UPDATED
ALL FIELDS BASED ON THE LATEST CONDITIONS AND TRENDED THEM INTO THE
GOING FCST AFTER MIDNIGHT. OTHERWISE...LITTLE CHANGE TO LATER
PERIODS.

AS OF 710 PM...LARGE AREA OF PRECIP STILL WELL TO THE WEST BEHIND
THE COLD FRONT ENTERING THE AREA. THIS AREA OF PRECIP WILL ONLY
SLOWLY MOVE IN...MAINLY AFTER MIDNIGHT. A FEW SHRA HAVE DEVELOPED TO
THE SW AND WILL MOVE ACROSS THE MTNS THIS EVENING. HAVE UPDATED POPS
TO REFLECT THESE TRENDS. TEMPS ARE RUNNING QUITE WARM AS WELL.
HOWEVER...GUIDANCE STILL SHOWS WINTRY PRECIP DEVELOPING ALONG THE TN
BORDER NEAR DAYBREAK THEN SPREADING ACROSS THE MTNS DURING THE DAY.
HAVE MADE SOME MINOR UPDATES BASED ON THE LATEST TRENDS AND
GUIDANCE. THIS DID AFFECT SNOW FALL TOTALS...GENERALLY SLIGHTLY
DOWNWARD...BUT COMBO OF ICE AND SNOW STILL WARRANT CURRENT ADVISORY.

AS OF 335 PM...A QUICK UPDATE TO ACCOUNT FOR CLEARING SKIES AND
WARMER TEMPS. HAVE ALSO SLOWED PRECIP ONSET PER REGIONAL RADAR.

AS OF 200 PM EST WEDNESDAY...STRATUS ASSOCIATED WITH REMNANT COOL
POOL IS FINALLY LIFTING AND MIXING OUT ACROSS THE PIEDMONT. MAX
TEMPS SHOULD STILL BE ABLE TO REACH THE UPPER 60S TO AROUND 70 EVEN
WHERE CLOUDS PERSISTED. REGIONAL RADARS INDICATE THE REMAINDER OF
THE AFTERNOON SHOULD REMAIN DRY AS PRECIP ASSOCIATED WITH THE COLD
FRONT IS STILL BACK OVER EAST CENTRAL TN.

FOR THE OVERNIGHT...THE COLD FRONT WILL BEGIN MAKING PROGRESS
SOUTHEASTWARD AS A SHORT WAVE MOVES SE INTO THE GREAT LAKES BY EARLY
THU AND THEN TO NEW ENGLAND BY THU EVENING. THE FRONT IS A CLASSIC
ANAFRONT IN THAT THE ASSOCIATED PRECIP IS LOCATED MOSTLY BEHIND THE
FRONT. HENCE...WILL RAMP UP POPS WITH THE EXPECTED FRONTAL PASSAGE
AND THEN HOLD ON TO THEM FOR A RATHER LONG DURATION. THE FRONT WILL
PUSH THROUGH MOST OF WESTERN NC BY 12Z THU AND THEN THROUGH NE GA
AND UPSTATE SC DURING THE MORNING. WITH MOST OF THE PRECIP FALLING
BEHIND THE FRONT IN THE COLD AIR...SOME PRECIP TYPE PROBLEMS EMERGE.
THE SHALLOW COLD AIRMASS WILL LOWER SURFACE TEMPS TO FREEZING OR
BELOW OVER MOST OF THE MOUNTAINS AND PERHAPS THE NORTHERN FOOTHILLS.
HENCE...A PERIOD OF FREEZING RAIN IS LIKELY...GRADUALLY
TRANSITIONING TO A PERIOD OF SLEET...AND THEN EVEN TO SNOW IN SOME
AREAS WHERE THE COLUMN HAS A CHANCE TO COOL THROUGH THE WARM NOSE.
USED A TOP DOWN APPROACH FOR WX GRIDS WHICH BRINGS FREEZING RAIN
INTO A LARGE PORTION OF THE MOUNTAINS...WITH MOST OF THE SLEET/SNOW
OCCURRING OVER THE TN BORDER COUNTIES. WILL ISSUE A WINTER WEATHER
ADVISORY ON THURSDAY FOR ALL OF THE TN BORDER COUNTIES EXTENDING
INTO THE CENTRAL MOUNTAINS AND INTO THE NORTHERN NC FOOTHILLS.
ELSEWHERE...JUST A COLD RAIN IS ANTICIPATED.

TEMPS WILL BE MILD OVERNIGHT...ESPECIALLY IN NE GA...UPSTATE SC AND
THE SOUTHERN NC PIEDMONT WHERE THE COLD FRONT WILL NOT ARRIVE. ON
THE FLIP SIDE...MIN TEMPS WILL FALL TO NEAR FREEZING IN THE TN
BORDER COUNTIES BY 12Z THU.

ON THU...A NON-DIURNAL TEMPERATURE TRACE WILL OCCUR WITH TEMPS
FALLING. THE PIEDMONT AREAS WILL SEE MAX TEMPS OCCUR IN THE MORNING
(UPPER 50S TO LOWER 60S) AND THEN FALL INTO THE UPPER 30S TO LOWER
40S BY THE END OF THE DAY.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
AS OF 130 PM EST WEDNESDAY...THE SHORT TERM FCST PERIOD INITIALIZES
THURSDAY EVENING AMONGST AN UPPER TROF DIGGING ACROSS THE MID
MISSISSIPPI RIVER VALLEY LEADING TO FALLING HEIGHTS OVER THE
SOUTHERN/CENTRAL APPS.  AT THE SURFACE...SLOW MOVING ANAFRONT WILL
BE SPREADING THROUGH THE REGION WITH SOME WINTRY PRECIP OF CONCERN
EARLY ON IN THE PERIOD.  POPS WILL INITIALIZE AT SLIGHT CHANCE
LEVELS ACROSS MUCH OF THE SC/NC/GA HIGH TERRAIN WITH LOW END CHANCE
POPS FAVORED FURTHER EAST ALONG AND SOUTH OF INTERSTATE 85 IN CLOSER
PROXIMITY TO THE PRIMARY MOISTURE AXIS.  AT THAT TIME...CAA REGIME
IN FULL EFFECT ACROSS THE CENTRAL/NORTHERN NC MTNS WILL LEAD TO A
WINTRY MIX OF PRECIPITATION...MAINLY ALONG AND NORTH OF THE
INTERSTATE 40 CORRIDOR.  CRITICAL THICKNESS VALUES ALONG WITH LATEST
FCST SOUDNINGS INDICATE MOSTLY SLEET/SNOW FAVORED...WITH PERHAPS
SOME VERY BRIEF PERIODS OF FREEZING RAIN ON THE SOUTHERN MOST FRINGE
OF THE ADVECTING COLD AIRMASS.  EITHER WAY...NOT EXPECTING THIS TO
AMOUNT TO MUCH INTO THE EVENING AS POPS FALL OFF SHARPLY WITH A DRY
FCST PREVAILING REGIONWIDE BY MIDNIGHT.

BEYOND THAT...HIGH PRESSURE WILL SLIDE ACROSS THE OH VALLEY BEFORE
SETTING UP A BRIEF CAD WEDGE REGIME FOR FRIDAY.  IN
RESPONSE...CLOUDY SKIES WILL PREVAIL EARLY ON BEFORE SCT OUT THROUGH
THE AFTERNOON HOURS.  THIS COMBINED WITH LIGHT NE FLOW AT THE
SURFACE WILL LIKELY YIELD HIGH TEMPS ON FRIDAY NEARLY 1-2 CATS BELOW
NORMAL.  CONDITIONS WILL RECOVER SOMEWHAT ON SATURDAY AS MOSTLY
SUNNY SKIES DOMINATE AMONGST GRADUALLY SOUTHERLY VEERING FLOW.  WEAK
WAA REGIME WILL ALLOW FOR MODERATING TEMPS WITH HIGHS SURGING TO
JUST BELOW NORMAL ON SATURDAY.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
AS OF 210 PM EST WEDNESDAY...THE MEDIUM RANGE FCST PICKS UP AT 00Z
ON SUNDAY WITH VERY BROAD UPPER TROFFING OVER THE EASTERN CONUS AND
MULTIPLE EMBEDDED UPPER SHORTWAVES PASSING OVER THE GREAT LAKES
REGION. OVER THE NEXT COUPLE OF DAYS...THE PATTERN GRADUALLY
DEAMPLIFIES AND WEAK UPPER RIDGING BEGINS TO BUILD OVER THE SE
REGION BY NEXT WEDNESDAY. THE LATEST 12Z GFS IS A BIT MORE BULLISH
WITH THE UPPER RIDGE COMPARED TO THE ECMWF...YET BOTH SOLUTIONS
TREND IN THE SAME DIRECTION.

AT THE SFC...DRY HIGH PRESSURE WILL STILL BE IN CONTROL OF THE
PATTERN AT THE START OF THE PERIOD. AS WE MOVE INTO MONDAY
AFTERNOON...THE GFS TRIES TO BRIEFLY RESTRENGTHEN THE HIGH AS IT
SLIDES EASTWARD AND PUTS THE CAROLINAS UNDER A WEAK CAD PATTERN. THE
ECMWF AND THE CANADIAN SOLUTIONS DO NOT STRENGTHEN THE HIGH AS MUCH
AND ALLOW A BROAD AREA OF DEEP LYR MOISTURE...THAT ORIGINATES TO OUR
SW...TO MOVE INTO THE CWFA BY EARLY TUES. BY 12Z...THE GFS ALSO HAS
THE SAME PLUME OF DEEP MOISTURE OVERSPREADING THE CWFA YET IT
MAINTAINS A MORE PERSISTENT NELY SFC WIND. BEYOND THIS POINT...THE
GFS KEEPS THE DEEP MOISTURE OVER THE FCST AREA THRU THE REMAINDER OF
THE MEDIUM RANGE WHILE THE ECMWF DRIES THINGS OUT BY EARLY WED AND
KEEPS THE DEEPER MOISTURE JUST TO OUR SOUTH. AS FOR THE SENSIBLE
FCST...I AM CONFIDENT THAT SUN WILL BE DRY AND MOST OF MON WILL
LIKELY BE DRY AS WELL WITH ONLY SOME SLIGHT CHANCE POPS IN THE FCST.
THE REST OF THE PERIOD IS PRETTY UNCERTAIN WITH SLIGHT TO SOLID
CHANCE POPS FOR THE CWFA. I THINK THE GFS IS TOO OPTIMISTIC WITH ITS
PRECIP FCST...ESPECIALLY ON TUES...AND THE ECMWF IS TOO DRY ON WED.
TEMPS SHOULD PERSIST RIGHT AROUND CLIMATOLOGY WITH LOWS A BIT WARMER
THAN NORMAL FOR EARLY/MID MARCH.

&&

.AVIATION /05Z THURSDAY THROUGH MONDAY/...
AT KCLT AND THE PIEDMONT TERMINALS...SHOWER CHANCES WILL SLOWLY
INCREASE OVERNIGHT AHEAD OF AN APPROACHING COLD FRONT WITH SOUTHERLY
WINDS LIKELY TO CONTINUE THROUGH DAYBREAK. A TRICKY TIMING SITUATION
EXISTS FOR THE PERIOD AT AND AFTER SUNRISE WHEN A WIND SHIFT TO
NORTH BECOMES LIKELY...CIGS CRASH TO IFR AND RAINFALL CVRG BECOME
CATEGORICAL. AN INCREASINGLY BRISK NNELY FLOW IS LIKELY TO DEVELOP
AS THE DAY WEARS ON WITH A SLOW IMPROVEMENT IN CIG RESTRICTIONS
THROUGH SUNSET. BONAFIDE RAIN CHANCES SHOULD ALSO DECREASE
DRAMATICALLY AFTER SUNSET AS CIGS CONTINUE TO IMPROVE.

AT KAVL...SHOWER AND CIG RESTRICTION CHANCES QUICKLY INCREASE
OVERNIGHT WITH STEADY RAIN AND IFR CIGS LIKELY TO CONTINUE INTO
A GOOD PART OF THE DAYLIGHT HOURS. IT REMAINS TO BE SEEN IF
TEMPERATURES CAN FALL ENUF FOR FREEZING RAIN LATER THIS AFTERNOON
AND WILL MAINTAIN A PROB GROUP TO ADDRESS THREAT. IFR CIGS SHOULD
IMPROVE TO MVFR BEFORE SUNSET. SLY WINDS SHOULD SWITCH TO NW WITHIN
THE NEXT FEW HOURS...THEN GUSTY NLY NEAR DAYBREAK AND CONTINUING
THRU THE DAY.

OUTLOOK...DRYING CONDITIONS WILL CONTINUE TO OVERSPREAD THE FA
TONIGHT RESULTING IN A RETURN TO VFR CONDITIONS BEFORE DAYBREAK
ON FRIDAY. VFR CONDITIONS ARE EXPECTED TO PERSIST THEN THROUGH THE
WEEKEND.

CONFIDENCE TABLE...

            13-19Z        19-01Z        01-07Z        07-12Z
KCLT       HIGH  95%     HIGH 100%     HIGH 100%     HIGH 100%
KGSP       HIGH 100%     HIGH 100%     HIGH 100%     HIGH 100%
KAVL       MED   74%     HIGH 100%     HIGH 100%     HIGH 100%
KHKY       MED   77%     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...WINTER WEATHER ADVISORY FROM 6 AM THIS MORNING TO 6 PM EST
     THIS EVENING FOR NCZ033-048>053-058-059.
SC...NONE.

&&

$$
SYNOPSIS...DEO
NEAR TERM...LG/RWH
SHORT TERM...CDG
LONG TERM...JPT
AVIATION...CSH/RWH


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