Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 011152
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
652 AM EST SUN FEB 1 2015

.SYNOPSIS...
LOW PRESSURE WILL MOVE UP THE OHIO VALLEY TODAY AND CROSS THE
APPALACHIANS NORTH OF THE FORECAST AREA TONIGHT. A COLD FRONT
TRAILING THIS LOW PRESSURE SYSTEM WILL CROSS THE REGION FROM THE
WEST DURING THE MORNING HOURS MONDAY. COOL AND DRY HIGH PRESSURE
WILL BUILD OVER THE REGION THROUGH TUESDAY AND MOVE OFFSHORE ON
WEDNESDAY. ANOTHER COLD FRONT WILL MOVE INTO THE AREA FROM THE
NORTHWEST ON THURSDAY...WITH DRYING OCCURRING INTO NEXT WEEKEND.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 645 AM...MADE SOME MINOR ADJUSTMENTS TO SKY AND TEMP/DEWPT PER
LATEST SATELLITE AND OBS. THE FCST APPEARS ON TRACK IN LIGHT OF
LATEST GUIDANCE.

SETTLED WEATHER WILL CONTINUE THRU THE EARLY PART OF
THE DAY TODAY AS HIGH PRESSURE PERSISTS OVER THE CAROLINA COAST.
UPPER LEVEL MOISTURE IS ALREADY STREAMING OVER THE AREA IN ADVANCE
OF A SFC LOW OVER THE PLAINS...WHICH WILL TRACK STEADILY EWD THRU
THE OHIO VALLEY THRU MON MRNG...PUSHING THE HIGH OFFSHORE. A SFC
COLD FRONT WILL MAKE ITS WAY ACRS THE LOWER MISSISSIPPI VALLEY THIS
AFTN...CROSSING OUR CWFA LATE TONIGHT. WIDESPREAD RAINFALL WILL
PRECEDE THE FRONT.

MAINLY MID-HIGH CLOUD COVER WILL BE SEEN THRU THE DAY WITH LOWER
CLOUDS ARRIVING DURING THE AFTERNOON AS WARM UPGLIDE STRENGTHENS.
LLVL FLOW IS STEADILY SWLY SO IT CAN BE EXPECTED THAT THE SW NC MTNS
AND AREAS ALONG THE BLUE RIDGE ESCARPMENT WILL SEE PRECIP CHANCES
RAMP UP FIRST. MODELS HAVE TRENDED LATER INTO THE DAY WITH THE ONSET
OF QPF...THE GFS BEING A BIT SLOWER THAN THE NAM...BUT THE
JUST-ARRIVED 06Z NAM FIELDS LOOK MORE LIKE THE GFS. NOTABLY THE 00Z
4KM SPC WRF DOES NOT BRING PRECIP TO THE UPSLOPE AREAS UNTIL 22-23Z.
THUS THE ONSET WAS DELAYED A BIT IN THE FCST. PRECIP IS EXPECTED
THROUGHOUT THE CWFA BY 06Z...BUT FOR THE MOST PART POPS DIMINISH
RAPIDLY BEHIND THE FROPA IN THE HRS JUST PRIOR TO DAYBREAK. SELECTED
A BLEND OF QPF NEAR THE SREF MEANS...APPRECIABLE BUT NOT ENOUGH FOR
HYDRO CONCERNS.

AS THE FLOW VEERS TO NWLY BEHIND THE FRONT...THE MTNS WILL CONTINUE
TO SEE PRECIP EVEN AS OTHER AREAS SEE IT DIMINISH. WITH WARM
ADVECTION OCCURRING THRU MOST OF THE NIGHT AT ALL ELEVATIONS...TEMPS
WILL BE RATHER STEADY IN THE 40S MTNS AND LOW 50S PIEDMONT. RAPID
COOLING IS LIKELY IN THE HIGH ELEVATIONS WHICH SHOULD ALLOW SNOW
LEVELS TO DESCEND AFTER 09Z OR SO. ENOUGH MODEL QPF IS PRESENT TO
WARRANT A MENTION OF A QUICK INCH OR MORE OF SNOW ACCUM ON THE HIGHER
RIDGETOPS BEFORE 12Z MON. GUIDANCE IS OPTIMISTIC AND KEEPS MOST TEMPS
WARM ENOUGH TO PRECLUDE SNOW...SO CONFIDENCE ON A HEADLINE EVENT IS
NOT HIGH. A HIGH ELEVATION WINTER WX ADVISORY COULD BE ISSUED TODAY
IF THE COLD ADVECTION SETS IN SOONER OR STRONGER THAN CURRENTLY
ANTICIPATED.

VERY STRONG 850-700MB WINDS ARE SEEN IN THE WARM SECTOR OF THE
LOW...WHICH SPREAD OVER OUR AREA THIS AFTN. CLOUD COVER APPEARS TO
LIMIT MIXING ENOUGH TO PREVENT STRONG GUSTS IN THE PIEDMONT...BUT THE
HIGH ELEVATIONS OF THE MTNS /PARTICULARLY SW OF THE FRENCH BROAD
VALLEY/ WILL LIKELY SEE FREQUENT GUSTS ABOVE 40 KT BY LATE AFTN. THE
WINDS ALOFT WILL INCREASE UNTIL THE FROPA OCCURS...WITH AN IMPRESSIVE
LLVL JET OVERNIGHT. THE HIGH ELEVATION WIND ADVY WILL BE MAINTAINED
AS-IS.

A VERY SMALL AMOUNT OF ELEVATED INSTABILITY IS SHOWN ON NAM/GFS PROG
SOUNDINGS TONIGHT. THE STRONG FLOW WILL CREATE IMPRESSIVE LLVL
SHEAR...BUT THE INSTABILITY IS FOR PARCELS LIFTED FROM THE WARM
NOSE...ABOVE THE BEST SHEAR. A COUPLE RUMBLES OF THUNDER IN THE AREA
WOULD NOT BE SURPRISING...BUT NO SEVERE WX IS EXPECTED.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 3 AM EST SUNDAY...A SMARTLY AMPLIFIED CLIPPER TYPE WAVE WILL
BE STRETCHED ALONG THE APPALACHIANS AROUND 12Z MONDAY...THEN MOVE
SWIFTLY TO THE ERN SEABOARD BY 18Z BEFORE EXITING OFF THE COAST.
THIS FEATURE WILL DRIVE THE ASSOCIATED SFC COLD FRONT QUICKLY EAST
OF THE AREA AS WELL MONDAY MORNING...WITH SNOW LEVELS DROPPING
ACROSS THE MTNS INTO THE LOWER VALLEYS. STRONG COLD ADVECTION IN THE
W TO NW UPSLOPE FLOW ALONG WITH ABUNDANT SFC TO 850 MB MOISTURE ARE
EXPECTED ACROSS THE WRN MTNS THROUGH MIDDAY MONDAY. NEARLY 50 KT OF
WIND IS EXPECTED AT THE TOP OF THE MIXED LAYER ALONG THE NRN BLUE
RIDGE. A WIND ADVISORY WILL MOST CERTAINLY BE NEEDED AT SOME POINT
FOR THIS AREA...AND POSSIBLY NEARBY AREAS...AND LOCALLY HIGH WINDS
CANNOT BE RULED OUT NEAR THE IMMEDIATE BLUE RIDGE WITH MIXING ON
MONDAY. BREEZY TO WINDY CONDITIONS WILL OCCUR EAST OF THE MTNS WITH
MIXING AS WELL. IN ADDITION...HIGHER ELEVATIONS OF THE WRN MTN SPINE
COUNTIES ARE LIKELY TO APPROACH OR EXCEED ADVISORY SNOW
ACCUMULATIONS BY MIDDAY MONDAY. A WINTER WEATHER ADVISORY COULD BE
NEEDED FOR THE ACCUMULATING SNOW OR BLOWING SNOW AS WELL. WILL
CONTINUE TO MENTION BOTH OF THESE HAZARDS IN THE HWO UNTIL THE
TIMING AND EXTENT OF THE HAZARDS BECOMES BETTER DEFINED...LIKELY
LATER THIS AFTERNOON. IT MAY BE POSSIBLE TO WRAP BOTH WIND AND SNOW
HAZARDS INTO A SINGLE PRODUCT AT THAT TIME FOR AT LEAST THE
MOUNTAINS.

A MUCH WEAKER SHORTWAVE WILL CROSS THE REGION ON TUE. ANY MID LEVEL
MOISTURE WITH THIS FEATURE SHOULD IMPACT MAINLY THE NRN TIER OF THE
FORECAST AREA. EXPECT MORNING MINS IN THE TEENS MTNS AND LOWER TO
MIDDLE 20S EAST. TUE AFTN MAXES SHOULD PEAK AT 5 TO 10 DEGREES BELOW
CLIMO.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 310 AM EST SUNDAY...ZONAL FLOW ALOFT IS EXPECTED ON WED...WITH
A SRN TIER LOW OPENING UP OVER SRN TX...WHILE ADDITIONAL NRN STREAM
ENERGY DIGS E OF THE ROCKIES. THE GFS REMAINS MORE AMPLIFIED AND
SLOWER WITH THE DIGGING SYSTEM INTO THE MS RIVER VALLEY ON THU AND
THEN ACROSS THE SE EARLY FRI. A CONSENSUS SOLUTION FOLLOWING MAINLY
ENSEMBLE MEAN FORECASTS BRINGS A COLD FRONT INTO THE REGION THU WITH
THE NRN STREAM...WITH VERY LOW END POPS FOCUSED MAINLY IN THE SRN
HALF AS ANY SFC LOW IN THE NRN GULF OF MEXICO PASSES WELL SOUTH OF
THE AREA. DRIER HIGH PRESSURE WILL START TO BUILD OVER FROM THE N
THROUGH FRI AND SETTLE IN PLACE OVER THE REGION BY SATURDAY.
FORECAST CONFIDENCE REMAINS LOW THROUGH THE PERIOD GIVEN THE MODEL
INCONSISTENCY IN HANDLING FEATURES APPROACHING THE SOUTHEASTERN U.S.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
AT KCLT...S TO SW FLOW WILL PREVAIL THRU THE PERIOD...AS COASTAL
HIGH PRESSURE GIVES WAY TO LOW PRESSURE COMING FROM THE WEST. SAID
LOW WILL BRING AN INCREASING CHC FOR PRECIP THRU THE DAY WHICH PEAKS
LATE TONIGHT. WINDS WILL ALSO PICK UP TONIGHT...BUT SIGNIFICANT
GUSTS UNLIKELY DUE TO POOR MIXING. BKN MIDLEVEL CIGS WILL PERSIST
UNTIL A LOW VFR DECK SPREADS IN LATE AFTN ON STRENGTHENING AND
MOISTENING FLOW ABOVE THE BDY LAYER. RESTRICTIONS ARE NOT EXPECTED
UNTIL RAIN GETS GOING IN THE EVENING...WITH MOST GUIDANCE SUGGESTING
IFR WILL FORM AFTER MIDNIGHT IF NOT SOONER. LIFR NOT OUT OF THE
QUESTION BUT WITH PRECIP RATES FAIRLY LIGHT THIS WILL BE OMITTED.
THE VERY FAST FLOW ALOFT COULD PRODUCE A LLWS THREAT IN THE
AREA...BUT BEING HARD TO PINPOINT FROM GUIDANCE THIS ALSO WILL BE
OMITTED.

ELSEWHERE...VFR THRU AT LEAST EARLY AFTERNOON WHEN THE MOISTENING
FLOW AHEAD OF THE LOW BEGINS TO SPREAD IN MVFR CIGS FROM THE SW AND
RAIN CHANCES RAMP UP FROM W TO E. LAMP CIG TRENDS LOOK FINE THRU
EARLY EVENING. S TO SW OVER MOST OF THE AREA DURING THE
DAY...GRADUALLY INCREASING INTO TONIGHT WITH THE TIGHTENING
GRADIENT. SIGNIFICANT GUSTS ARE LIKELY IN THE HIGH ELEVATIONS BY
LATE AFTN AND ESPECIALLY TONIGHT. HOWEVER THESE DO NOT LOOK LIKELY
TO MIX DOWN. IFR SHOULD FORM AFTER ONSET OF PRECIP....AND SOME
GUIDANCE BLANKETS THE WHOLE AREA WITH LIFR BY LATE EVENING. HOWEVER
THIS SEEMS A BIT OVERDONE GIVEN THE EXPECTED PRECIP RATES...BUT
AREAS ALONG THE BLUE RIDGE WILL SEE SOME ENHANCED LIFT SO IT IS
MENTIONED AT KGSP/KGMU.

OUTLOOK...RAIN AND LOWER CIGS/VSBY EXPECTED IN PARTS OF THE AREA
INTO MON MRNG. DRYING NW FLOW IS EXPECTED ON THE BACK SIDE OF THE
SYSTEM BY LATE MONDAY...BUT WILL BE ACCOMPANIED BY GUSTY WINDS...ESP
AT KAVL. ANOTHER MOIST LOW PRESSURE SYSTEM MAY AFFECT THE REGION
LATE IN THE WEEK.

CONFIDENCE TABLE...

            12-18Z        18-24Z        00-06Z        06-12Z
KCLT       HIGH 100%     HIGH 100%     HIGH  84%     HIGH  80%
KGSP       HIGH 100%     HIGH  90%     MED   64%     MED   76%
KAVL       HIGH 100%     HIGH  88%     HIGH  87%     HIGH  86%
KHKY       HIGH 100%     HIGH  95%     MED   67%     MED   78%
KGMU       HIGH 100%     HIGH  90%     MED   61%     MED   76%
KAND       HIGH 100%     HIGH  81%     MED   61%     MED   78%

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...WIND ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM EST MONDAY FOR
     NCZ048-051-052-058-059-062>064.
SC...NONE.

&&

$$
SYNOPSIS...HG
NEAR TERM...WIMBERLEY
SHORT TERM...HG
LONG TERM...HG
AVIATION...WIMBERLEY


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