544
FXUS62 KCAE 091801
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
201 PM EDT WED JUL 9 2025
SYNOPSIS
A BIT COOLER TODAY WITH WIDESPREAD SHOWERS AND STORMS LIKELY AS
AN UPPER TROUGH APPROACHES. THE THREAT FOR DAMAGING WINDS AND
FLASH FLOODING WILL EXIST BOTH TODAY AND THURSDAY WITH HEAVY
RAINFALL EXPECTED. THE UPPER TROUGH IS REPLACED BY RIDGING LATE
IN THE WEEK AND THIS WEEKEND, ALLOWING TEMPERATURES TO SLOWLY
RISE WITH TYPICAL SUMMERTIME SHOWERS AND STORMS.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- WIDESPREAD STORMS EXPECTED THIS AFTERNOON WITH AN ASSOCIATED FLASH
FLOOD AND DAMAGING WIND THREAT THIS AFTERNOON & EVENING.
SHOWERS AND THUNDERSTORMS HAVE BEEN DEVELOPING ACROSS THE MIDLANDS
AND CSRA OVER THE LAST HOUR OR TWO. THIS IS THE RESULT OF AN
APPROACHING MID LEVEL TROUGH AND COPIOUS MOISTURE IN THE PRESENCE OF
STRONG HEATING. TEMPERATURES HAVE RISEN INTO THE LOW 90S WITH
DEWPOINTS IN THE LOW TO MID 70S, YIELDING NOT ONLY HEAT INDICES IN
THE LOW TRIPLE DIGITS, BUT SBCAPE VALUES UPWARDS OF 4000 J/KG.
MOISTURE CONVERGENCE HAS PUSHED PWAT'S OVER 2.0" FOR JUST ABOUT ALL
OF THE FORECAST AREA. GIVEN SATURATED SOUNDINGS AND WEAK
STEERING FLOW/SHEAR, WE'RE STILL DEALING WITH BOTH A FLASH FLOOD
AND SEVERE THUNDERSTORM THREAT TODAY. THE WIND THREAT WILL
LIKELY STEM FROM WATER LOADED DOWNDRAFTS, GIVEN DCAPE VALUES
LESS THAN 800 J/KG SIGNALING A LACK OF DRY AIR ALOFT. THE 12Z
HREF SUITE FEATURES SOME WEAK SIGNS OF ORGANIZATION, WITH A LINE
OF STORMS PUSHING THROUGH THE FORECAST AREA FROM WEST TO EAST
AFTER ABOUT 09/22Z. THAT SAID, GUIDANCE HAS BEEN A COUPLE OF
HOURS SLOWER THAN ACTUAL DEVELOPMENT, SO THIS MAY END UP
HAPPENING SOONER THAN EXPECTED. WE CONTINUE TO CARRY A WPC
SLIGHT RISK ERO FOR OUR ENTIRE AREA AND SPC HAS CONTINUED THEIR
SLIGHT RISK FOR THE NORTHERN MIDLANDS, WITH MARGINAL ELSEWHERE.
WHILE ITS EXPECTED THAT MOST CONVECTION WILL START TO DIMINISH
IN THE FEW HOURS AFTER SUNSET, A FEW MODELS SHOW STORMS
PERSISTING INTO THE FIRST HALF OF THE OVERNIGHT PERIOD, SO
WOULDN'T BE SURPRISED TO SEE SOME LINGERING CONVECTION THROUGH
MIDNIGHT OR SO. DEBRIS CLOUDS WILL THEN KEEP TEMPERATURES ON THE
WARMER SIDE, WITH LOW ONLY IN THE LOW TO MID 70S AND THE
POTENTIAL FOR SOME PATCHY FOG OR STRATUS TO DEVELOP FOR AREAS
WHICH SAW THE HEAVIER RAINFALL AMOUNTS.
SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/
KEY MESSAGE(S):
- POTENTIAL FOR STRONG TO MARGINALLY SEVERE STORMS MAINLY
THURSDAY, BUT POSSIBLE AGAIN ON FRIDAY.
- THE FLASH FLOOD POTENTIAL CONTINUES THROUGH THE SHORT TERM AS
HIGH MOISTURE AND WEAK STEERING FLOW CONTINUES.
AN ACTIVE SHORT TERM PERIOD CONTINUES TO BE EXPECTED AS THE
UPPER TROUGH WORKS THROUGH THE FA THURSDAY BEFORE BEGINNING TO
EXIT TOWARD FRIDAY EVENING AND OVERNIGHT. FORCING FROM THE
TROUGH WILL CONTINUE TO INFLUENCE SENSIBLE WEATHER EACH DAY
WHERE THE WHOLE CWA IS OUTLINE IN A SLIGHT RISK (LEVEL 2 OUT OF
5) FOR SEVERE WEATHER ON THURSDAY AND A MARGINAL RISK ON FRIDAY
(LEVEL 1 OUT OF 5). FOR THURSDAY, WEAK UPPER FORCING ALONG WITH
SOME SURFACE MOISTURE CONVERGENCE SHOULD DRIVE SCATTERED TO
WIDESPREAD SHOWERS AND STORMS ACROSS THE AREA DURING THE
AFTERNOON/EVENING. THE ENVIRONMENT HAS LONG SKINNY CAPE PROFILES
WITH MLCAPE ON THE ORDER OF 2000-2500 J/KG AND PWAT'S THAT
REMAIN NEAR 2.0-2.2", THOUGH THE DEGREE IN WHICH THE ATMOSPHERE
DESTABILIZES IS A BIT UNCERTAIN AS INCREASED CLOUD COVER IS
EXPECTED THURSDAY MORNING INTO THE AFTERNOON. DEEP LAYER SHEAR
REMAINS WEAK, BUT HAS SLIGHTLY INCREASED FROM PREVIOUS FORECAST
SOUNDINGS TO AROUND 15 KTS. DUE TO THIS, A COUPLE LOOSELY
ORGANIZED CLUSTERS COULD FORM AND POSSIBLY GROW UPSCALE SOME IF
A STRONG COLD POOL DEVELOPS. THE VERY MOIST SOUNDINGS, AND AT
LEAST MODESTLY STEEP 0-3KM LAPSE RATES, BRING THE MAIN THREAT OF
DAMAGING WINDS FROM POTENTIAL WET DOWNBURSTS, BUT THE OTHER
CONCERN, ESPECIALLY DEPENDING ON WHICH LOCATIONS SEE RAINFALL
TODAY, WILL BE THE POTENTIAL FOR ISOLATED SPOTS OF FLASH
FLOODING. CURRENTLY, THE CWA IS OUTLINED IN WPC'S MARGINAL RISK
(LEVEL 1 OUT OF 4) FOR EXCESSIVE RAINFALL THURSDAY BUT A SLIGHT
RISK (LEVEL 2 OUT OF 4) DOES EXTENDED INTO THE PEE DEE REGION.
WITH WEAK STEERING FLOW ONCE AGAIN OVERHEAD, SLOW STORM MOTIONS
ARE EXPECTED AND WHEN COUPLED WITH LONG/SKINNY CAPE PROFILES
OVER A DEEPLY MOIST ATMOSPHERIC COLUMN, EFFICIENT RAINFALL IS
LIKELY WHERE THE 12Z HREF LPPM HIGHLIGHTS LOCALIZED SPOTS OF
2-4" BEING POSSIBLE. AGAIN, THE AREAS AT HIGHEST RISK FOR THIS
POTENTIAL WILL PARTIALLY BE DRIVEN BY RAINFALL RECEIVED TODAY
AND HOW SOIL MOISTURES AND LOCAL BASINS RESPOND. THIS ACTIVITY
IS EXPECTED TO DWINDLE IN COVERAGE AND INTENSITY INTO THE
OVERNIGHT HOURS.
FRIDAY SEES THE TROUGH PIVOT OVERHEAD AND FINALLY OUT OF THE
REGION BY THE EVENING AND OVERNIGHT, THOUGH PWATS REMAIN NEAR 2"
STILL WITH A POSSIBLE SHORTWAVE THAT REACHES THE FA BY THE
EARLY AFTERNOON. THIS SHOULD DRIVE ANOTHER ROUND OF SCATTERED TO
WIDESPREAD SHOWERS/STORMS, WITH A COUPLE ON THE STRONG SIDE
POSSIBLE, AGAIN DUE TO THE POTENTIAL FOR DOWNBURST WINDS FROM
PRECIP LOADED DOWNDRAFTS AS SHEAR AND STEERING FLOW REMAIN WEAK.
LIKE THURSDAY, SOME ENHANCED CLOUD COVER TO START THE DAY
BRINGS IN UNCERTAINTY IN HOW MUCH INSTABILITY CAN BUILD. WITH
PWAT'S SLOWLY LOWERING DUE TO MOISTURE TRANSPORT VECTORS TURNING
A BIT MORE WESTERLY AND UPPER FORCING SLOWLY MOVING OUT, THE
POTENTIAL FOR ISOLATED FLASH FLOODING IN SPOTS IS A BIT LOWER
THAN THURSDAY, THOUGH THIS COULD EASILY CHANGE BASED ON WHERE
SLOW-MOVING CONVECTION MOVES OVER TODAY AND THURSDAY.
SHOWERS/STORMS LOOK TO MOVE OUT WITH THE UPPER SUPPORT DURING
THE EVENING AND OVERNIGHT AS RIDGING SLOWLY REPLACES THE TROUGH.
LONG TERM /SATURDAY THROUGH TUESDAY/
KEY MESSAGE(S):
- TEMPERATURES RETURN TO ABOVE NORMAL VALUES THIS WEEKEND INTO
MONDAY AS UPPER RIDGING REDEVELOPS.
- SHOWER/STORM CHANCES BECOME MORE DIURNALLY DRIVEN.
UPPER RIDGING CONTINUES TO BE EXPECTED TO TAKE GRIP THROUGH THE
WEEKEND AND INTO THE EARLY WEEK, LEADING TO INCREASED TEMPERATURES
AND HEAT INDICES THAT NEAR 105F MAINLY SUNDAY AND MONDAY. RETURNING
SEASONABLE MOISTURE UNDER THE RIDGE BRINGS TYPICAL DIURNAL
SHOWER/STORM CHANCES EACH DAY BEFORE THERE IS A LEAST A WEAK SIGNAL
IN GLOBAL MODELS THAT THE RIDGE COULD BREAK DOWN SLIGHTLY TOWARD
TUESDAY, POSSIBLY BRINGING CLOSER TO NORMAL TEMPERATURES AND
INCREASED POP'S EACH DAY.
AVIATION /18Z WEDNESDAY THROUGH MONDAY/
PREDOMINATELY VFR AT ALL TAF SITES, THOUGH WIDESPREAD SHOWERS AND
THUNDERSTORMS ARE LIKELY THIS AFTERNOON AND EVENING WITH THE
POTENTIAL FOR CIG/VSBY RESTRICTIONS.
SCT-BKN CU FIELD WITH BASES 3.5-5KFT MSL CONTINUES TO DEVELOP THIS
AFTERNOON ALONG WITH SCT-NUM SHRA/TSRA. AS SUCH, BRIEF CIG/VSBY
RESTRICTIONS LIKELY IN THE STRONGER CELLS, PARTICULARLY DUE TO
EXPECTED HEAVY RAINFALL. LINGERING CONVECTION IS EXPECTED WELL INTO
THE EVENING, POSSIBLY AS LATE AS 10/08Z THURSDAY. OUTSIDE OF ANY
CONVECTIVE GUSTINESS, SURFACE WINDS SHOULD GENERALLY REMAIN SLY AT
LESS THAN 10 KTS. LIGHT AND VARIABLE WINDS OVERNIGHT. LOW END CHANCE
FOR A STRATUS DECK AND PATCHY FOG DEVELOPMENT THURSDAY MORNING JUST
BEFORE DAYBREAK. THURSDAY AFTERNOON WILL FEATURE ANOTHER ROUND OF
CONVECTION WITH THE POTENTIAL FOR GUSTY WINDS AND RESTRICTIONS AT
ALL TAF SITES.
EXTENDED AVIATION OUTLOOK...THERE IS THE POSSIBILITY OF
DIURNALLY DRIVEN SHOWERS AND THUNDERSTORMS THIS WEEK WITH THE
POTENTIAL FOR PERIODIC RESTRICTIONS.
CAE WATCHES/WARNINGS/ADVISORIES
SC...NONE.
GA...NONE.
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