Area Forecast Discussion
Issued by NWS Greer, SC

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000
FXUS62 KGSP 191115
AFDGSP

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
715 AM EDT SUN APR 19 2015

.SYNOPSIS...
A VERY MOIST WARM FRONT WILL LIFT NORTHEAST ACROSS THE AREA TODAY. A
COLD FRONT WILL THEN CROSS THE AREA ON MONDAY...USHERING IN
SEASONABLE TEMPERATURES AND DRY CONDITIONS THROUGH MIDWEEK. ANOTHER
COLD FRONT WILL CROSS THE AREA FROM THE NORTHWEST ON THURSDAY.

&&

.NEAR TERM /THROUGH TONIGHT/...
AS OF 715 AM...WIDESPREAD SHRA DEVELOPING NEARLY ON SCHEDULE...AND
WILL CONTINUE THRU THE DAY. HAVE SLOWED THE ONSET OF TSRA AS THERE
IS NOT EVEN ANY IN CLOUD LIGHTNING SHOWING UP TO THE WEST.
OTHERWISE...GOING FCST ON TRACK WITH UPDATES MAINLY FOR CURRENT
CONDITIONS.

AS OF 335 AM...PRIMARY FCST CONCERN THROUGH THE NEAR TERM REMAINS
THE POTENTIAL FOR HEAVY RAIN ACROSS MUCH OF THE AREA TODAY. THE
CURRENT WATCH LOOKS TO BE WELL PLACED WITH QPF UP TO 3 INCHES
POSSIBLE IN THE WATCH AREA. SHRA ARE DEVELOPING ACROSS THE CWFA AND
WILL CONTINUE TO EXPAND IN COVERAGE AND INCREASE IN INTENSITY THRU
THE MORNING...WITH WIDESPREAD COVERAGE BY MIDDAY. IN ADDITION TO THE
HEAVY RAIN POTENTIAL... GUIDANCE SHOWS WEAK INSTABILITY WILL DEVELOP
ACROSS THE AREA TODAY. THE GUIDANCE ALSO SHOWS MODERATE BULK SHEAR
ALONG WITH HIGH LEVELS OF 0-1KM HELICITY. THE FCST HODOGRAPHS ARE
GREATLY CURVED AS WELL. ALL THIS WOULD INDICATE A HIGH SHEAR/LOW
CAPE ENVIRONMENT DEVELOPING TODAY AS THE WARM FRONT TO OUR SOUTH
MOVES ACROSS THE AREA. THAT SAID...FCST SHERB VALUES REMAIN BELOW 1
TODAY. WE ARE IN A SLIGHT RISK FOR SEVERE STORMS TODAY...SO THIS
WILL NEED TO BE WATCHED THRU THE DAY. SHOULD SEE GUSTY WINDS
DEVELOPING ACROSS THE AREA IN ANY CASE AS THE FRONT MOVES THRU.

CONVECTION WILL MOVE EAST OF THE AREA DURING THE EVENING WITH A
DIMINISHING POP TREND. HOWEVER...SOME GUIDANCE SHOWS A SECONDARY
LINE OF CONVECTION MOVING THRU EARLY IN THE EVENING...THEN A
TERTIARY LINE OF CONVECTION MOVING IN TOWARD DAYBREAK AS SHORT WAVES
ROTATE ACROSS THE AREA. KEEP HIGHER POP EARLY EVENING DIMINISHING
AROUND MIDNIGHT...THEN PICKING BACK UP THRU DAYBREAK. COULD BE SOME
LINGERING HEAVY RAIN DURING THE EVENING...WITH MUCH LOWER QPF
EXPECTED AFTER MIDNIGHT. GUST WINDS WILL DIMINISH THRU THE EVENING.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
AS OF 300 AM SUNDAY...MODELS IN GOOD AGREEMENT ON A COLD FRONT
CROSSING THE AREA DURING THE DAY ON MONDAY. THE FRONT SHUD HAVE
SOLID 1500-2000 J/KG OF SBCAPE AND 35-45 KT OF GENERALLY
UNIDIRECTIONAL SHEAR TO WORK WITH. THE NEW DAY 2 SPC CONVECTIVE
OUTLOOK HAS EXPANDED THE SLGT AND MRGL RISK AREAS A BIT FURTHER WEST
OVER OUR AREA TO LINE UP WITH THE EXPECTED FRONTAL TIMING. THERE
WILL BE ANOTHER LOBE OF VORTICITY TO HELP SUPPORT CONVECTION...BUT
DEEP LAYER MOISTURE WILL BE THINNING DUE TO A STRONG DRY SLOT OVER
THE AREA. SO WILL GO WITH GENERALLY HIGH-END CHC TO LOW LIKELY POPS
MONDAY AFTN ACRS THE ENTIRE CWFA. THE MAIN THREATS LOOK TO BE
DAMAGING WIND GUSTS AND AN ISOLD TORNADO THREAT EAST OF THE MTNS.
LARGE HAIL WILL ALSO BE POSSIBLE. HIGHS WILL BE ABOUT 8-10 DEG ABOVE
NORMAL.

THE FRONT AND ASSOCIATED CONVECTION SHUD EXIT EAST OF THE AREA BY
MID EVENING...WITH A LINGERING SHWR THREAT ALONG THE TN BORDER
WITHIN NW FLOW. TEMPS WILL BE A CATEGORY OR TWO ABOVE NORMAL.

TUESDAY THRU TUESDAY NIGHT LOOKS DRY...AS SFC HIGH PRES BUILDS IN
UNDER QUASI-ZONAL FLOW ALOFT. TEMPS WILL BE BACK TO AROUND NORMAL.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
AS OF 315 AM SUNDAY...THE UPPER PATTERN WILL CHANGE LITTLE OVER THE
MEDIUM RANGE...WITH A LOW SPINNING OVER THE GREAT LAKES...AND SPLIT
FLOW UPSTREAM ACRS MOST OF THE CONUS. A SOUTHERN STREAM SHORTWAVE
TROF IS EXPECTED TO EVENTUALLY EJECT OUT ACRS THE PLAINS AND BRING A
RETURN OF MORE UNSETTLED WX FOR THE CWFA. THE LATEST WPC GUIDANCE
WAS BLENDED INTO THE FCST WITH THIS PACKAGE. THIS RESULTS IN NEAR
NORMAL TEMPS FOR WEDNESDAY AND THURSDAY...WITH A SLGT CHC TO LOW-END
CHC POP FOR THURSDAY WITH A REINFORCING COLD FRONT FROM THE NW.
BELOW NORMAL TEMPS FOR FRIDAY AND SATURDAY WITH AN INCREASE IN POPS
TO MID CHC TO LOW LIKELY BY SATURDAY.

&&

.AVIATION /11Z SUNDAY THROUGH THURSDAY/...
AT KCLT...SHRA AND MVFR TEMPO IFR RESTRICTIONS WILL CONTINUE EARLY
THIS MORNING WITH IFR FOR THE LATE MORNING/EARLY AFTERNOON. IFR AND
PROB30 TSRA FROM LATE AFTERNOON INTO THE EVENING. EXPECT MVFR TO
DEVELOP WITH PRECIP ENDING NEAR MIDNIGHT...THEN IFR CIGS TOWARD
DAYBREAK. SE WIND TODAY BECOME GUSTY FOR THE AFTERNOON THEN SW WIND
TONIGHT.

ELSEWHERE...GENERALLY SIMILAR TREND TO KCLT THOUGH AN EARLIER ONSET.
ALSO...LESS CHC OF TSRA KHKY. KAVL WILL SEE SLY WIND THRU THE PERIOD.

OUTLOOK...A COLD FRONT WILL SWEEP THROUGH THE REGION ON MONDAY WITH
STRONG TO SEVERE THUNDERSTORMS BEING A POSSIBILITY. RESTRICTIONS
WILL BE LIKELY AT TIMES ON MONDAY FOR ALL SITES. HIGH PRESSURE WILL
BUILD IN BEHIND THE COLD FRONT LEADING TO LOWER PRECIP/RESTRICTION
CHANCES.

CONFIDENCE TABLE...

            11-17Z        17-23Z        23-05Z        05-06Z
KCLT       HIGH  85%     LOW   56%     MED   64%     MED   73%
KGSP       HIGH  93%     MED   62%     MED   62%     HIGH 100%
KAVL       HIGH  85%     MED   65%     HIGH  83%     HIGH 100%
KHKY       HIGH 100%     LOW   56%     MED   78%     MED   73%
KGMU       HIGH  93%     MED   62%     MED   71%     HIGH  80%
KAND       HIGH  93%     LOW   52%     HIGH  83%     LOW   53%

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...FLOOD WATCH THROUGH THIS EVENING FOR GAZ010-017-018-026-028.
NC...FLOOD WATCH THROUGH THIS EVENING FOR NCZ033-035>037-049-050-
     053-056-057-062>065-068>072-501>510.
SC...FLOOD WATCH THROUGH THIS EVENING FOR SCZ001>010.

&&

$$
SYNOPSIS...ARK
NEAR TERM...RWH
SHORT TERM...ARK
LONG TERM...ARK
AVIATION...RWH


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