348
FXUS62 KGSP 142351
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
751 PM EDT FRI AUG 14 2020
SYNOPSIS
NUMEROUS TO WIDESPREAD SHOWERS AND THUNDERSTORMS ARE EXPECTED
THROUGH SATURDAY WITH HIGHS SLIGHTLY BELOW NORMAL. THUNDERSTORM
CHANCES DIMINISH SUNDAY THEN SLOWLY INCREASE THROUGH THE WEEK. HIGHS
WILL BE AROUND NORMAL THROUGH THE FIRST PART OF THE WEEK THEN FALL
BELOW NORMAL.
NEAR TERM /THROUGH SATURDAY/
AS OF 740 PM EDT FRIDAY: WATER VAPOR IMAGERY SHOWS THE BASE OF A
DIGGING TROUGH STEADILY ADVANCING EASTWARD ACROSS WESTERN TENNESSEE
THIS EVENING, WITH BETTER FORCED CONVECTIVE COVERAGE DEVELOPING
UPSTREAM ACROSS ALABAMA AND GEORGIA. COVERAGE HAS BEEN SPARSER AND
WEAKER ACROSS THE WESTERN CAROLINAS AND NORTHEAST GEORGIA THUS FAR,
AND WHAT OUTFLOWS EXIST AT PRESENT DO NOT LOOK TERRIBLY ROBUST. POPS
HAVE THUS BEEN SHAVED A BIT IN PIEDMONT SECTIONS, BUT WITH CONTINUED
LIKELY COVERAGE ACROSS THE HIGHER TERRAIN AND THE NC FOOTHILLS FOR
ONGOING SHOWERS AND EMBEDDED THUNDERSTORMS. IT'S QUITE POSSIBLE THAT
THE REGION WILL STILL EXPERIENCE AN UPTICK TONIGHT AS THE UPSTREAM
COVERAGE ARRIVES FROM THE SOUTHWEST LATER THIS EVENING, BUT SBCAPE
VALUES WILL START TRENDING DOWN SOON AND THERE MAY NOT BE GOOD
INSTABILITY TO GET COVERAGE BACK UP ABOVE THE HIGH SCATTERED RANGE.
WILL KEEP THE BEST OVERNIGHT POPS IN SOUTHWEST MOUNTAIN SECTIONS,
CLOSER TO THE DEEPER MOISTURE AND FORCING AND WHERE UPSLOPE FLOW
WILL BE BEST. WILL LIKELY ALLOW THE FLASH FLOOD WATCH TO EXPIRE ON
SCHEDULE AT MIDNIGHT, WITH JUST ABOUT ANY LOCATION POSSIBLY SEEING
LOCALIZED FLOODING WITH ANY TRAINING SHOWERS OVERNIGHT.
POPS WILL RAMP UP A BIT SOONER THAN TYPICAL DIURNAL TRENDS INDICATE
ON SATURDAY, AS UPPER DPVA AND JET ENERGY BEGINS TO PUSH EAST INTO
THE AREA. THE BEST 2+ INCH PRECIPITABLE WATER VALUES OF THE EVENT
WILL OCCUR ON SATURDAY, AND THE DEEP FORCING, ABUNDANT MOISTURE AND
SLIGHTLY IMPROVED LAPSE RATES SHOULD YIELD MORE COVERAGE, STRONGER
STORMS, AND A SLIGHT UPTICK IN THE HYDRO THREAT WITH ANY TRAINING
CELLS. A NEW FLASH FLOOD WATCH COULD BE NEEDED AT SOME POINT
SATURDAY WHERE ANTECEDENT RAINFALL CONDITIONS ARE THE WETTEST
(MAINLY WESTERN NC). EXPECT MILD AND MUGGY CONDITIONS OVERNIGHT, AND
THEN BELOW CLIMO MAXES SATURDAY AFTERNOON GIVEN ALL THE CLOUD COVER.
SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/
AS OF 200 PM EDT FRIDAY: THE MID LEVEL TROF WILL BE PULLING EAST OF
THE AREA BY SATURDAY NIGHT. WE SHOULD HAVE SOME SHOWERS AND STORMS
IN THE EVENING, BUT THEY WILL MOVE EAST OF THE AREA LEAVING A DRY
OVERNIGHT PERIOD. AS THE TROF MOVES EAST, A DRIER AIR MASS WILL
MOVE INTO THE AREA FOR SUNDAY AND MONDAY AS NORTHWEST MID LEVEL FLOW
DEVELOPS. THERE WILL BE A SMALL CHANCE OF A SHOWER OR STORM EACH DAY
BUT CONDITIONS SHOULD BE QUIET OVERALL.
HIGHS BOTH DAYS WILL BE NEAR CLIMO. SLIGHTLY LOWER DEWPOINTS WILL
MAKE CONDITIONS RELATIVELY COMFORTABLE FOR MID AUGUST.
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
AS OF 200 PM EDT FRIDAY: ANOTHER MID LEVEL TROF IS EXPECTED TO
DEVELOP TO OUR WEST FOR THE MIDDLE TO LATTER PART OF NEXT WEEK. THIS
SHOULD ACT TO PULL DEEPER MOISTURE BACK INTO THE AREA LEADING TO A
MORE ACTIVE, MAINLY DIURNAL, CONVECTIVE PATTERN. THE INCREASED CLOUD
COVER AND RAINFALL SHOULD KEEP HIGH TEMPERATURES IN CHECK AND A FEW
DEGREES BELOW CLIMO THROUGH THE PERIOD.
AVIATION /00Z SATURDAY THROUGH WEDNESDAY/
AT KCLT AND ELSEWHERE: CONVECTION CHANCES WILL BE BEST THIS
EVENING FROM KAVL TO KHKY, BUT WITH A SHARP GRADIENT TO LOWER
CHANCES ACROSS THE UPSTATE TAF SITES AND KCLT, WHERE MAINLY VCSH OR
VCTS IS WARRANTED THROUGH EARLY OVERNIGHT. ABUNDANT MOISTURE SHOULD
YIELD ANOTHER ROUND OF LOW CLOUDS AND FOG, WITH IFR TO LIFR
CONDITIONS MAINLY FROM KAVL TO KHKY, BUT WITH MVFR LIKELY AT THE
OTHER SITES, INCLUDING KCLT, AND A WINDOW OF IFR POSSIBLE AS WELL.
RESTRICTIONS WILL BE SLOW TO LIFT THROUGH NOON, AND INSOLATION WILL
BE LIMITED BY ABUNDANT CLOUDS THROUGH THE AFTERNOON HOURS. EXPECT
MAINLY AFTERNOON VFR CONDITIONS BUT WITH MVFR TO IFR POSSIBLE IN ANY
HEAVY DOWNPOURS. THE BEST CONVECTIVE CHANCES WILL BE DURING THE
AFTERNOON AND EVENING HOURS AS THE UPPER TROUGH MAKES A PUSH INTO
THE REGION. EXPECT VERY SLOW DRYING TO BEGIN FROM THE WEST RIGHT
AROUND THE END OF THE TAF PERIOD, BUT WITH LOW-LEVEL MOISTURE
PERSISTING. LIGHT AND VARIABLE WINDS WILL BE MAINLY S TO SW WITH ANY
MIXING TONIGHT THROUGH SATURDAY, EXCEPT NW AT TIMES IN THE FRENCH
BROAD VALLEY TONIGHT. WINDS WILL BE BRIEFLY GUSTY NEAR ANY
THUNDERSTORMS.
OUTLOOK: SLIGHTLY LESS THUNDERSTORM COVERAGE IS EXPECTED SUNDAY AND
MONDAY COMPARED TO RECENT DAYS, BUT PERHAPS STILL SLIGHTLY ABOVE
NORMAL AS LOW-LEVEL MOISTURE CONTINUES. AN UPTICK IN THUNDERSTORM
COVERAGE IS THEN LIKELY TUESDAY THROUGH WEDNESDAY. FOG AND LOW
STRATUS RESTRICTIONS WILL BE POSSIBLE EACH MORNING, ESPECIALLY OVER
THE USUAL MOUNTAIN VALLEYS.
CONFIDENCE TABLE...
00-06Z 06-12Z 12-18Z 18-00Z
KCLT HIGH 97% MED 78% MED 69% HIGH 96%
KGSP HIGH 98% MED 71% MED 73% HIGH 88%
KAVL MED 74% LOW 58% MED 78% MED 75%
KHKY HIGH 90% MED 62% MED 65% MED 78%
KGMU HIGH 98% MED 70% MED 68% HIGH 90%
KAND HIGH 98% MED 78% MED 79% HIGH 94%
THE PERCENTAGE REFLECTS THE NUMBER OF GUIDANCE MEMBERS AGREEING
WITH THE SCHEDULED TAF ISSUANCE FLIGHT RULE CATEGORY. COMPLETE HOURLY
EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLES ARE AVAILABLE AT
THE FOLLOWING LINK:
WWW.WEATHER.GOV/GSP/AVIATION
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NCZ033-
035>037-056-057-501>506.
SC...NONE.
SYNOPSIS...DEO
NEAR TERM...HG
SHORT TERM...SCW
LONG TERM...SCW
AVIATION...HG
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