955
FXUS62 KGSP 120707
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
307 AM EDT SUN JUL 12 2026
WHAT HAS CHANGED
CONFIDENCE IS INCREASING AGAIN THAT COOLER AIR WILL INFILTRATE THE
AREA EARLY THIS WEEK, AND MAX TEMPS HAVE TRENDED DOWN (10+ DEGREES
BELOW NORMAL) FOR MON/TUE.
KEY MESSAGES
1. VERY ACTIVE CONVECTIVE WEATHER IS EXPECTED TO CONTINUE THROUGH
AT LEAST MONDAY. ISOLATED SEVERE STORMS AND LOCALIZED FLASH
FLOODING WILL BE POSSIBLE EACH DAY THROUGH MONDAY. OTHERWISE, A
COOLING TREND IS EXPECTED, WITH WELL-BELOW NORMAL HIGH TEMPERATURES
FORECAST MONDAY AND TUESDAY.
2. A RETURN TO SEASONABLY HOT CONDITIONS AND TYPICAL COVERAGE OF
DIURNAL SHOWERS AND STORMS IS EXPECTED DURING THE LATTER HALF OF
NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: VERY ACTIVE CONVECTIVE WEATHER IS EXPECTED TO CONTINUE
THROUGH AT LEAST MONDAY. ISOLATED SEVERE STORMS AND LOCALIZED FLASH
FLOODING WILL BE POSSIBLE EACH DAY THROUGH MONDAY. OTHERWISE, A
COOLING TREND IS EXPECTED, WITH WELL-BELOW NORMAL HIGH TEMPERATURES
FORECAST MONDAY AND TUESDAY.
ISOLATED TO SCATTERED CONVECTION CONTINUES ACROSS THE REGION
THIS MORNING, WITH THE BEST COVERAGE NOTED ACROSS THE NC
MOUNTAINS. HOWEVER, EVEN THIS ACTIVITY HAS BEEN WEAKENING
SUBSTANTIALLY AS IT CROSSES THE CREST OF THE APPALACHIANS FROM
EAST TN SUCH THAT MORNING POPS WILL MAINLY BE 10-30% FOR LOCATIONS
SOUTH AND EAST FROM THE COUNTIES BORDERING TN. CANNOT RULE OUT AN
ISOLATED FLASH FLOOD EVENT THIS MORNING ACROSS THE LOWER REACHES
OF THE FRENCH BROAD BASIN, AS AREAS OF MADISON COUNTY AND VICINITY
HAVE SEEN SOLID 2-4 INCH RAINFALL TOTALS IN THE PAST 24 HOURS.
A BACKDOOR FRONT WILL GRADUALLY SAG SOUTHWEST ACROSS THE FORECAST
AREA THROUGHOUT THE DAY...ALTHOUGH THE MAIN PUSH OF LOWER THETA-E
AIR INTO OUR AREA IS FORECAST TO HOLD OFF UNTIL TONIGHT. WITH THE
BULK OF THE FORECAST AREA EXPECTED TO REMAIN FREE OF CONVECTION
AND THICK CLOUD COVER THIS MORNING, MUCH OF THE AREA (ESPECIALLY
EAST OF THE MOUNTAINS) SHOULD HAVE NO ISSUE DESTABILIZING TO THE
TUNE OF 2000 J/KG (GIVE OR TAKE) OF SBCAPE. MEANWHILE, AN AREA OF
HEIGHT FALLS WILL DRIFT SOUTH ACROSS THE OHIO AND TN VALLEYS THIS
MORNING...WITH A WEAK UPPER LOW EXPECTED TO TAKE SHAPE ACROSS THE
TN VALLEY BY LATE TODAY. ACCELERATING MID-LEVEL FLOW IS FORECAST
TO IMPROVE SHEAR PARAMETERS (AROUND 25 KTS THROUGH A DEEP LAYER)
ACROSS OUR AREA TODAY. IN OTHER WORDS...SHEAR WILL BE IMPROVED OVER
THE PAST COUPLE OF DAYS...WHEN CONVECTION HAS BEEN ABLE TO MAKE
THE ABSOLUTE MOST OF RELATIVELY MODEST BUOYANCY TO PRODUCE AREAS OF
SEVERE WEATHER. THE SPC SLIGHT RISK FOR SEVERE STORMS LOOKS PRUDENT
AND WELL PLACED ACROSS THE PIEDMONT THIS AFTERNOON, ESPECIALLY IN
LIGHT OF THE FACT THAT THE SYNOPTIC AND MESOSCALE PATTERN SHOULD
FAVOR GOOD COVERAGE (POPS OF 70-80% IN MOST LOCATIONS) OF DIURNAL
SHOWERS AND STORMS.
OF EQUAL CONCERN WILL BE THE INCREASED POTENTIAL FOR LOCALLY
EXCESSIVE RAINFALL, ESPECIALLY LATER IN THE DAY THROUGH TONIGHT AS
THE FLOW TURNS EASTERLY UPSLOPE...WHICH WILL INTERACT WITH VERY
MOIST CONDITIONS (PWATS AROUND 2") AND WARM CLOUD DEPTHS OVER 10
KFT TO UP THE HEAVY RAINFALL ANTE. CELL TRAINING COULD ALSO BECOME
A CONCERN ALONG THE SURFACE BOUNDARY. COMBINED WITH LOCALLY POOR
ANTECEDENT CONDITIONS RESULTING FROM HEAVY RAINFALL OVER THE PAST
THREE DAYS WARRANTS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS
MUCH OF THE CWA THROUGH TONIGHT.
PRECIP CHANCES REMAIN HIGH MONDAY INTO MONDAY NIGHT, AS MOISTURE
CONTENT REMAINS HIGH AND LOW LEVEL UPSLOPE FLOW PERSISTS. HAVING
SAID THAT, WIDESPREAD THICKER CLOUD COVER AND ADVECTION OF LOWER
THETA-E AIR INTO THE CWA IS EXPECTED TO RESULT IN WEAK-AT-MOST
INSTABILITY MONDAY AFTERNOON, SO THE HEAVY RAINFALL THREATS BEGINS
TO GET A LITTLE MURKIER. AS SUCH, THE BIGGER STORY MONDAY MAY BE
THE MUCH COOLER WEATHER EXPECTED AS A CONSEQUENCE OF THE EASTERLY
FLOW/CLOUDY/SHOWERY REGIME. FORECAST MAXES ARE MORE THAN 10 DEGREES
BELOW CLIMO.
RELATIVELY COOL/MOSTLY STABLE AND SHOWERY CONDITIONS CONTINUE INTO
TUESDAY...ALTHOUGH GUIDANCE SIGNALS ADVECTION OF DRIER AIR INTO
THE HEART OF THE FORECAST AREA FROM THE N AND NE. STILL CAN'T RULE
OUT SOME DEGREE OF A HEAVY RAINFALL THREAT AROUND THE SOUTHERN AND
WESTERN PERIPHERY OF THE CWA TUESDAY, BUT MUCH OF THE AREA MAY
WELL BE FREE OF CONVECTION TUE AFTERNOON. FORECAST MAXES REMAIN
AROUND 10 DEGREES BELOW NORMAL TUE.
KEY MESSAGE 2: A RETURN TO SEASONABLY HOT CONDITIONS AND TYPICAL
COVERAGE OF DIURNAL SHOWERS AND STORMS IS EXPECTED DURING THE
LATTER HALF OF NEXT WEEK.
BY MID-WEEK, A REX BLOCK IF FORECAST TO BECOME ESTABLISHED ACROSS
THE CENTRAL CONUS, WITH A BROADENING ANTICYCLONE/ATTENDANT RIDGE
FORECAST TO BE CENTERED ACROSS THE CENTRAL/NORTHERN GREAT PLAINS. AS
WEAKENING UPPER LOW RETROGRADES ACROSS THE DEEP SOUTH, HEIGHTS
WILL RISE ACROSS OUR REGION, BRINGING A RETURN OF SEASONABLY HOT
CONDITIONS. LOW LEVEL MOISTURE AND INSTABILITY ARE FORECAST TO BE
ADEQUATE TO SUPPORT TYPICAL COVERAGE OF DIURNAL CONVECTION FROM
WED ONWARD...WITH MAINLY WIDELY SCATTERED ACTIVITY EXPECTED ACROSS
THE MOUNTAINS, AND ISOLATED COVERAGE ELSEWHERE.
AVIATION /07Z SUNDAY THROUGH THURSDAY/
AT KCLT AND ELSEWHERE: CONVECTION IS MOVING ACROSS THE SOUTHERN
APPALACHIANS EARLY THIS MORNING, AND COULD IMPACT KAVL BETWEEN
NOW AND 09Z. THE BULK OF THE ACTIVITY IS EXPECTED TO PASS NORTH OF
THERE, SO WILL RIDE WITH A VCSH FOR THE TIME BEING. LITTLE-TO-NONE
OF THIS CONVECTION IS EXPECTED TO SURVIVE THE TREK OVER THE HIGH
TERRAIN, SO WILL OMIT ANY CONVECTIVE MENTION AT THE OTHER TAF
SITES FOR THIS MORNING. AMPLE LOW LEVEL MOISTURE CREATES SOME
CAUSE FOR CONCERN OF FOG AND/OR LOW STRATUS DEVELOPING OVER THE
AREA THIS MORNING. WE'RE ALREADY SEEING IT IN THE USUAL MOUNTAIN
VALLEYS WEST OF KAVL, BUT LOCALIZED AREAS OF LOW STRATUS ARE ALSO
BEGINNING TO SHOW THEMSELVES ACROSS THE PIEDMONT. CONFIDENCE IN
CIG RESTRICTIONS AT THE TAF SITES IS LOW, BUT THE POTENTIAL IS
SUFFICIENT TO INCLUDE TEMPOS FOR FEW/SCT LIFR/IFR CLOUD LAYERS
AT ALL SITES BY DAYBREAK. MVFR VISBY IS ALSO INCLUDED AT THE
CLIMATOLOGICALLY FAVORED SITES AT KAVL AND KHKY.
THE AFTERNOON/EVENING IS EXPECTED TO BE MORE ACTIVE CONVECTION-WISE
THAN YESTERDAY, SUCH THAT TEMPOS FOR TSRA ARE WARRANTED AT ALL
SITES... BEGINNING AS EARLY AS 17Z AT KAVL, AND AS LATE AS 20Z AT
KCLT. THE CONVECTIVE POTENTIAL WILL LINGER INTO THE EVENING, AND
PROB30S REPLACE TEMPOS AFTER THE ALLOWED 4-HOUR TEMPO WINDOW. IN
FACT, CONDITIONS WILL BE FAVORABLE FOR AT LEAST ISOLATED CONVECTION
TO CONTINUE WELL INTO THE OVERNIGHT. GENERALLY LIGHT WSW WINDS
THIS MORNING ARE EXPECTED TO TURN TO THE NE THIS AFTERNOON.
OUTLOOK: GREATER THAN NORMAL COVERAGE OF SHRA/TSRA WILL CONTINUE
ACROSS OUR FCST AREA INTO MONDAY AS MULTIPLE ROUNDS OF STORMS ARE
EXPECTED ACROSS THE REGION. DRIER CONDITIONS SHOULD DEVELOP TUESDAY
INTO WEDNESDAY. LOW STRATUS AND/OR FOG WILL BE POSSIBLE EACH MORNING
IN THE MTN VALLEYS AND IN LOCATIONS THAT SEE APPRECIABLE RAINFALL
THE PREVIOUS AFTERNOON/EVENING.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...NONE.
SC...NONE.
JDL
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