Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 141428
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
1028 AM EDT MON APR 14 2014

.SYNOPSIS...
WARM SOUTHERLY FLOW WILL PROVIDE DEEP MOISTURE ACROSS THE REGION BY
THIS AFTERNOON. A COLD FRONT IS EXPECTED TO MOVE ACROSS THE AREA
ON TUESDAY. IN THE WAKE OF THE FRONT...A DRY AND UNSEASONABLY COOL
AIR MASS WILL REMAIN OVER THE REGION DURING THE REMAINDER OF THE
WORK WEEK.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 1010 AM...STRATUS DECK CONTINUES TO STREAM ACROSS THE AREA
LATE THIS MORNING AS MOST OF THE PRECIP REMAINS WELL TO OUR WEST AND
SW. A FEW POCKETS OF LIGHT SHOWERS HAVE MOVED OVER THE CENTRAL AND
NORTHERN MTS OF NC BUT THAT IS ABOUT IT THUS FAR. NO SIG CHANGES WERE
MADE TO THE OVERALL FCST FOR LATER TODAY/TONIGHT...HOWEVER ONSET OF
HEAVIER SHOWERS AND TSRA MAY BE DELAYED A FEW MORE HOURS AS THE
ANTICIPATED PROGRESSION OF THE SYNOPTIC FRONT COULD LIKELY SLOW.

AS OF 315 AM...THICK HIGH CLOUDS REMAIN OVER THE AREA WITH LOW
CLOUDS BEGINNING TO FORM. EXPECT THE LOW CLOUDS TO SPREAD ACROSS THE
AREA BY DAYBREAK...WITH ISOLATED SHRA FORMING ALONG AND NEAR THE
BLUE RIDGE IN THE INCREASING ISENTROPIC LIFT AND UPSLOPE FLOW.
EXPECT COVERAGE OF SHRA TO INCREASE TO NUMEROUS THRU THE MORNING
OVER THIS AREA AND BECOME SCATTERED ELSEWHERE. THE COVERAGE
CONTINUES TO INCREASE THRU THE AFTERNOON AS BETTER SYNOPTIC FORCING
MOVES IN WITH SHORT WAVES AND UPPER DIVERGENCE FROM UPPER JET MAX.
INSTABILITY DEVELOPS AS WELL...LEADING TO ISOLATED TO SCT TSRA
ACROSS MOST OF THE AREA. BREEZY SLY WINDS WITH LOW END GUSTS ARE
EXPECTED AS WELL...WITH HIGHS NEAR OR SLIGHTLY ABOVE NORMAL.

PRECIP COVERAGE INCREASES RAPIDLY FROM LATE AFTERNOON THRU EARLY
EVENING AS STRONG SYNOPTIC FORCING AND UPPER DIVERGENCE INCREASE.
INSTABILITY INCREASES DRAMATICALLY AS WELL WITH SREF MEAN CAPE FROM
500 TO 1000 J/KG ACROSS NE GA AND THE UPSTATE...WITH LESSER AMOUNTS
OVER NC. SREF MEAN ALSO SHOWS MODERATE AMOUNTS OF BULK SHEAR AND
HELICITY DEVELOPING ACROSS THE AREA. THE NAM IS SIMILAR IN ITS
DEPICTION OF INSTABILITY BUT IS EVEN MORE DIRE WITH IT SHEAR. THE
GFS AGREES WITH MODERATE TO STRONG SHEAR...WITH MUCH LESS...BUT NOT
ZERO...INSTABILITY. BEST OVERLAP OF SHEAR AND INSTABILITY LOOKS TO
BE ACROSS NE GA AND THE UPSTATE FROM LATE AFTERNOON THRU EARLY
EVENING. THAT SAID...CANNOT RULE OUT SOME OVERLAP ACROSS THE NC SRN
PIEDMONT BEFORE MIDNIGHT. SPC HAS NE GA AND THE UPSTATE IN A SEE
TEXT FOR SVR STORM POTENTIAL FROM MAINLY WIND DAMAGE. WILL INCLUDE
THIS AREA IN IN THE HWO HIGHLIGHTING THE POTENTIAL.

EXPECT WIDESPREAD SHRA AND SOME TSRA THRU THE REST OF THE NIGHT AS A
COLD FRONT APPROACHES...KEEPING THE AREA IN DEEP MOISTURE AND
FORCING. BREEZY WINDS WITH LOW END GUSTS WILL CONTINUE ACROSS THE
AREA AS WELL. LOWS REMAIN WELL ABOVE NORMAL AHEAD OF THE FRONT.

&&

.SHORT TERM /TUESDAY THROUGH TUESDAY NIGHT/...
AS OF 245 AM MONDAY...BY DAYBREAK TUESDAY...SHORT RANGE MODELS
INDICATE THAT THE SFC COLD FRONT WILL RUN NORTH TO SOUTH ACROSS THE
SOUTHERN APPALACHIANS. THE COLD FRONT IS EXPECTED TO PUSH WEST TO
EAST ACROSS THE FORECAST AREA DURING THE DAYLIGHT HOURS
TUESDAY...LIKELY PUSHING EAST OF THE CWA BY MID AFTERNOON. AT
H5...THE TROF AXIS IS EXPECTED RIPPLE FROM THE MISSISSIPPI VALLEY AT
12Z TUES TO THE WESTERN CAROLINAS BY 0Z WED. GFS INDICATES THAT A
SIGNIFICANT BAND OF MID LEVEL Q-VECTOR CONVERGENCE WILL MOVE ACROSS
THE FORECAST AREA ON TUESDAY. THE NAM FORECAST SOUNDINGS INDICATE
THAT 0-1 KM HELICITY VALUES WILL PEAK AROUND 400 M2/S2 DURING THE
EARLY DAYLIGHT HOURS ON TUESDAY. CAPE VALUES MAY SURGE ABOVE 500
J/KG ACROSS THE I-77 CORRIDOR BETWEEN 9Z-14Z. THE OVERLAP OF
SIGNIFICANT SYNOPTIC FORCING... WEAK/MARGINAL INSTABILITY...AND HIGH
HELICITY MAY SUPPORT A WINDOW FOR ORGANIZED CONVECTION EARLY TUESDAY
MORNING ACROSS THE PIEDMONT BETWEEN 9Z-14Z. THE OVERLAP OF
INSTABILITY AND HELICITY CERTAINLY APPEARS GREATER EAST OF THE
FORECAST AREA DURING THE AFTERNOON.

ON TUESDAY...IN THE WAKE OF THE COLD FRONT...CAA WILL LOWER H85
TEMPERATURES ACROSS THE MTNS FROM 1-3C AT 12Z TUES TO -5 TO -7C BY
18Z TUES. I WILL INDICATE COOLING MTN TEMPERATURES ACROSS THE MTNS
THROUGH THE DAY. IN FACT...HIGH TEMPERATURES WILL LIKELY OCCUR
AROUND MID DAY...WITH STEADY TO COOLING FOOTHILL AND PIEDMONT
TEMPERATURES DURING THE AFTERNOON. IN ADDITION...VEERING WINDS WILL
STRENGTHEN ACROSS THE MTNS IN THE WAKE OF THE FRONT TUESDAY
AFTERNOON THROUGH TUESDAY NIGHT. THE WINDS ACROSS PORTIONS OF THE
MTNS AND ADJACENT FOOTHILLS MAY REACH WIND ADVISORY CRITERIA LEVELS
BETWEEN 21Z TUES THROUGH 6Z WED. THE STRONG NORTHWEST WINDS AND
ONGOING CAA SHOULD RESULT IN MTN LOW TEMPERATURES INTO THE UPPER 20S
TUESDAY NIGHT. FOOTHILL AND PIEDMONT AREAS ARE FORECAST TO RANGE
FROM 30 TO 35 DEGREES.

&&

.LONG TERM /WEDNESDAY THROUGH SUNDAY/...
AS OF 320 AM MONDAY...THE POTENTIAL FOR FROST OR FREEZE WILL REMAIN
ACROSS THE MTNS AND PORTIONS OF THE NC FOOTHILLS AND PIEDMONT
WEDNESDAY NIGHT AND THURSDAY MORNING. DRY SFC RIDGING WILL PROVIDE
GOOD RADIATIONAL COOLING ACROSS THE REGION WEDNESDAY NIGHT. A BLEND
OF PREFERRED MOS SUPPORTS MIN TEMPERATURES FROM THE LOW 30S ACROSS
THE MTNS TO THE MID TO UPPER 30S EAST.

HIGH TEMPERATURES FROM WEDNESDAY THROUGH FRIDAY WILL LIKELY RANGE 8
TO 12 DEGREES BELOW NORMAL. TEMPERATURES WILL WARM CLOSE TO NORMAL
BY THE WEEKEND. THE GFS AND ECMWF INDICATES THAT A COLD FRONT AND
SOUTHERN STREAM LOW PRESSURE SYSTEM WILL DRIFT ACROSS THE SOUTHEAST
FRIDAY NIGHT AND SATURDAY...I WILL MAINTAIN CHC POPS FOR -SHRA. SFC HIGH
PRESSURE SHOULD SETTLE OVER THE REGION ON SUNDAY.

&&

.AVIATION /15Z MONDAY THROUGH FRIDAY/...
AT KCLT...TOOK A LITTLE LONGER THAN EXPECTED...BUT MVFR CLOUDS AND
CIGS FINALLY DEVELOPING ACROSS THE AREA. EXPECT THESE CIGS TO
CONTINUE THRU THE MORNING...THEN LIFTING TO LOW VFR FOR EARLY
AFTERNOON. COULD BE SOME SHRA FOR EARLY AFTERNOON...BUT BEST CHC OF
SHRA AND TSRA WILL BE LATE AFTERNOON. STARTED PROB30 AT THE EARLIEST
POSSIBLE TIME OF 21Z. TSRA CHC CONTINUES THRU THE NITE WITH CIGS
LOWERING TO MVFR THEN IFR. SLY WIND CONTINUES THRU THE PERIOD WITH
GUSTS FOR THE AFTERNOON AND OVERNIGHT.

ELSEWHERE...SIMILAR CONDITIONS TO KCLT...BUT EARLIER ONSET FOR THE
WESTERN SITES. KAVL LESS LIKELY TO HAVE TSRA UNTIL LATE TONIGHT WHEN
A COLD FRONT APPROACHES. HAVE INCLUDED A PRO30 FROM 09Z ON.

OUTLOOK...WIDESPREAD SHOWERS AND RESTRICTIONS WILL CONTINUE THRU
TUESDAY MORNING. A COLD FRONT WILL MOVE EAST OF THE AREA LATE
TUESDAY...WITH DRY HIGH PRESSURE SETTLING IN WED THROUGH LATE WEEK.

CONFIDENCE TABLE...

            14-20Z        20-02Z        02-08Z        08-14Z
KCLT       HIGH  92%     HIGH  92%     HIGH  81%     HIGH  88%
KGSP       HIGH  85%     HIGH  82%     HIGH  89%     HIGH  98%
KAVL       MED   77%     MED   76%     HIGH  95%     HIGH 100%
KHKY       HIGH  86%     HIGH  85%     HIGH  91%     HIGH 100%
KGMU       HIGH  84%     MED   76%     HIGH  95%     HIGH  98%
KAND       HIGH  85%     MED   78%     MED   73%     HIGH  89%

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...NED
NEAR TERM...JPT
SHORT TERM...NED
LONG TERM...NED
AVIATION...JPT






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