582
FXUS62 KGSP 222324
AFDGSP
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC
724 PM EDT WED JUL 22 2026
WHAT HAS CHANGED
UPDATED THE AVIATION DISCUSSION.
KEY MESSAGES
1. ISOLATED SEVERE STORMS ARE POSSIBLE THROUGH THIS EVENING,
WITH AN ESCALATING RISK OF HEAVY RAINFALL AND POTENTIAL FLASH
FLOODING TONIGHT THROUGH AT LEAST FRIDAY. A FLOOD WATCH IS IN
EFFECT TONIGHT THROUGH THURSDAY FOR MUCH OF WESTERN NC.
2. A RETURN TO TYPICAL LATE JULY WEATHER IS EXPECTED NEXT WEEK.
DISCUSSION
KEY MESSAGE 1: ISOLATED SEVERE STORMS ARE POSSIBLE THROUGH THIS
EVENING, WITH AN ESCALATING RISK OF HEAVY RAINFALL AND POTENTIAL
FLASH FLOODING TONIGHT THROUGH AT LEAST FRIDAY. A FLOOD WATCH IS IN
EFFECT TONIGHT THROUGH THURSDAY FOR MUCH OF WESTERN NC.
THE AXIS OF AN UPPER TROUGH WILL REMAIN OVER THE EAST THROUGH
THE END OF THE WEEK, BRINGING AN ACTIVE PERIOD OF CONVECTIVE
WEATHER. AS OF THIS AFTERNOON, THE LEADING EDGE OF A SLOW-MOVING
FRONTAL ZONE EXTENDS FROM MIDDLE TENNESSEE ENE TO ROUGHLY ALONG
THE WV/VA BORDER. THIS BOUNDARY HAS BEEN MOVING EVEN SLOWER THAN
EARLIER MODEL GUIDANCE HAD SUGGESTED, AND THIS SLOW-MOVING TREND
IS LIKELY TO CONTINUE UNTIL AN AREA OF MORE SUBSTANTIAL HEIGHT
FALLS PASSES OVER THE MID-ATLANTIC ON THU. WITH MEAN CLOUD-BEARING
WINDS ORIENTED ALMOST PERFECTLY WITH THE BOUNDARY ORIENTATION,
SHOWERS AND SCATTERED THUNDERSTORMS CONTINUE TO TRAIN AHEAD OF
THE BOUNDARY ACROSS EAST TENNESSEE AND NW NC/SOUTHERN VA, AND THIS
TRAINING ACTIVITY WILL CONTINUE TO BUILD GRADUALLY SOUTHEAST INTO
OUR CWA THROUGH THE AFTERNOON. AS A SW LOW LEVEL JET INCREASES TO
25-30 KTS TONIGHT, CONVERGENCE ALONG THE BOUNDARY WILL INCREASE AND
WILL INTERACT WITH TROPICAL PWATS OF OVER 2," WARM CLOUD DEPTHS OF
OVER 12 KFT, AND MODEST INSTABILITY POOLING ALONG THE BOUNDARY TO
RESULT IN TRAINING, HIGHLY EFFICIENT RAINFALL-PRODUCING CONVECTION
THAT WILL GRADUALLY SAG SOUTH THROUGH THE OVERNIGHT, WITH WIDESPREAD
1-2" RAINFALL AMOUNTS AND LOCALIZED AMOUNTS AS HIGH AS 5" EXPECTED
ACROSS MUCH OF WESTERN NC BY SUNRISE THURSDAY. A FLOOD WATCH FOR
FLASH FLOODING HAS BEEN ISSUED FOR ALMOST ALL OF OUR NC COUNTIES
FROM THIS EVENING THROUGH 00Z FRIDAY.
FOR LOCATIONS FARTHER SOUTH, TRAINING SHOWERS MAY NOT EVEN REACH THE
UPSTATE AND NORTHEAST GA UNTIL AFTER SUNRISE, AND WITH LINGERING
CONCERNS ABOUT THIS TIMING AND HOW CONVECTIVE TRENDS WILL EVOLVE
ON THURSDAY, THESE AREAS WILL BE LEFT OUT OF THE WATCH FOR THE
TIME BEING. HOWEVER, IT IS LIKELY THAT SOME AREAL EXTENSION TO THE
SOUTH WILL OCCUR AT SOME POINT TONIGHT, AS THE MAIN HEAVY RAINFALL
THREAT SAGS SOUTH WITH THE BOUNDARY.
WITH THE AFOREMENTIONED HEIGHT FALLS PASSING NORTH OF THE AREA
TOMORROW...FOLLOWED BY A 1020+ MB AREA OF SURFACE HIGH PRESSURE THAT
WILL BUILD INTO THE NORTHEAST BY THE END OF THE DAY...DEVELOPING
INVERTED RIDGE EAST OF THE APPALACHIANS SHOULD PUSH THE BOUNDARY
CLEAR OF THE CWA THU NIGHT. THIS WILL SPELL A DIMINISHING FLASH
FLOOD THREAT LATE TOMORROW INTO TOMORROW NIGHT/FRIDAY, BUT SOME
MARGINAL THREAT IS EXPECTED TO CONTINUE THROUGH THE END OF THE WEEK,
AS A SERIES OF WEAK UPPER WAVES INTERACT WITH AN ENVIRONMENT THAT
IS GENERALLY STABLE, YET STILL MOIST (ALBEIT NOT AS TROPICAL.)
OTHER THAN NEAR-NORMAL TEMPS ACROSS THE SOUTHERN TIER THU AFTERNOON,
TEMPERATURES (ESPECIALLY MAX TEMPS) ARE FORECAST TO BE AT LEAST
5-10 DEGREES BELOW NORMAL THROUGH SATURDAY UNDER THE INFLUENCE OF
ENE LOW LEVEL, ANOMALOUSLY LOW HEIGHTS, AND PLENTY OF AFTERNOON
STORMS AND/OR SHOWERS.
KEY MESSAGE 2: A RETURN TO TYPICAL LATE JULY WEATHER IS EXPECTED
NEXT WEEK.
A CONSENSUS OF GLOBAL MODELS INDICATES THE AXIS OF A LONG WAVE
TROUGH WILL SHIFT TO...OR JUST OFF THE ATLANTIC COAST BY SUNDAY,
AND GENERALLY REMAIN THERE THROUGH AT LEAST MID-WEEK, WITH THE
FLOW ALOFT SLOWLY BECOMING MORE ANTICYCLONIC AS A RIDGE BUILDS
STRONGLY ACROSS THE ROCKIES/GREAT PLAINS. THE RESULT WILL BE
A RETURN OF SEASONABLY HOT CONDITIONS, WITH TEMPS FORECAST TO
BE WITHIN A COUPLE OF DEGREES EITHER SIDE OF CLIMO FROM SUNDAY
ONWARD. THIS TIME FRAME WILL BE MUCH LESS CONVECTIVELY ACTIVE WITH
SHOWERS/STORMS MORE STRONGLY TIED TO THE DIURNAL HEATING CYCLE AS
WELL, WITH POPS MOSTLY IN THE 10-30% RANGE WARRANTED EACH DAY.
AVIATION /00Z THURSDAY THROUGH MONDAY/
AT KCLT AND ELSEWHERE: VFR CONDITIONS TO START BUT RESTRICTIONS COME
IN OVERNIGHT AS SHRA AND TSRA ARRIVE AT ALL TERMINALS. PROB30 FOR
TSRA AT ALMOST ALL SITES OVERNIGHT FOR TSRA AND MVFR VSBY/CIGS. SHRA
CONTINUES THURSDAY MORNING WITH A FEW TSRA POSSIBLE AT THE NC
TERMINALS. WINDS SHIFT FROM W/SW TO NE BETWEEN 18Z-22Z THURSDAY.
MVFR/IFR CIGS AND SHRA/-TSRA REMAIN TOWARD THE END OF THE FORECAST
AT MOST SITES.
OUTLOOK: RESTRICTIONS CONTINUE THROUGH FRIDAY AS SHOWERS AND
THUNDERSTORMS REMAIN. LOW STRATUS AND/OR FOG ARE POSSIBLE EACH
MORNING IN THE MOUNTAIN VALLEYS AND LOCATIONS WHICH RECEIVE
HEAVY RAINFALL.
GSP WATCHES/WARNINGS/ADVISORIES
GA...NONE.
NC...FLOOD WATCH THROUGH THURSDAY EVENING FOR NCZ033-035>037-
048>053-056>059-062>065-068>072-501>510.
SC...NONE.
JDL
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