340
FXUS62 KCAE 011710
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
110 PM EDT FRI AUG 1 2025
SYNOPSIS
HEAT AND HUMIDITY CONTINUES TODAY WITH WIDESPREAD SHOWERS AND
STRONG STORMS EXPECTED DURING THE LATE AFTERNOON AND EVENING.
THIS HEAT SPELL IS THEN EXPECTED TO BREAK AS A COLD FRONT IS
FORECAST TO BRING COOLER CONDITIONS FOR THE WEEKEND. CHANCES FOR
TYPICAL AFTERNOON AND EVENING SHOWERS AND THUNDERSTORMS
CONTINUE EACH DAY THROUGH THE FORECAST PERIOD.
NEAR TERM /THROUGH TONIGHT/
KEY MESSAGE(S):
- HEAT ADVISORY IN EFFECT FOR AREAS ALONG AND SOUTH OF I-20.
- SEVERE THUNDERSTORMS POSSIBLE LATE THIS AFTERNOON INTO
TONIGHT. STORMS WILL PRODUCE HEAVY RAIN AND GUSTY WINDS.
TODAY WILL BE THE LAST OF THE LONG STRETCH OF HOT AND HUMID
DAYS. THOUGH DEWPOINTS ARE LOWER TODAY, TEMPERATURES WILL AGAIN
REACH INTO THE MID 90S FOR MANY AREAS. HEAT ADVISORY CRITERIA
(108F) MAY BE MET THIS AFTERNOON BEFORE CONVECTION DEVELOPS BUT
ADDITIONAL CONSIDERATION WAS GIVEN TO THE FACT THAT THIS HAS
BEEN A LONG DURATION STRETCH OF DANGEROUS HEAT WHICH COULD LEAD
TO AN INCREASED RISK OF HEALTH IMPACTS.
ISOLATED STORMS ARE EXPECTED TO DEVELOP BY THE MID-AFTERNOON.
STRENGTHENING LOW LEVEL CONVERGENCE WILL LEAD TO THUNDERSTORMS
ACROSS THE NORTHERN PORTION OF THE FORECAST AREA AND IN THE
UPSTATE. AS CONVECTIVE COVERAGE INCREASES THROUGH THE AFTERNOON,
CAMS SHOW STORMS IN THE UPSTATE DEVELOPING A SE STORM MOTION,
POTENTIALLY GROWING INTO A CONVECTIVE SYSTEM IN THE EVENING AND
WORKING INTO CENTRAL SC. SEVERE THREAT IS A BIT HIGHER TODAY
COMPARED TO THE PREVIOUS DAYS WITH AN UPTICK IN DEEP LAYER SHEAR
LEADING TO MORE ORGANIZED MULTICELL CLUSTERS POSSIBLE. THIS
TYPE OF SUMMERTIME SETUP WITH EXTREMELY WARM, MOIST CONDITIONS
AND SOMEWHAT ORGANIZED CONVECTION TYPICALLY LEADS TO SEVERE
WEATHER IN THIS PART OF THE COUNTRY. WE WOULD EXPECT AT LEAST
ISOLATED DAMAGING WINDS WITH SOME POTENTIAL FOR AREAS OF
DAMAGING WINDS IF CONVECTION IS ABLE TO ORGANIZE.
FLOODING ALSO REMAINS A RISK. WHILE THE FLOW SHOULD ALLOW
STORMS TO MOVE, ANY TRAINING WILL LEAD TO A LOCALIZED FLASH
FLOODING RISK. STORMS ARE EXPECTED TO CONTINUE INTO THE EVENING
AND AT LEAST THE FIRST PART OF THE NIGHT. ALTHOUGH THE THREAT OF
DAMAGING WINDS WILL DECREASE TONIGHT. A COLD FRONT WILL PUSH
INTO THE AREA TONIGHT WHICH WILL LEAD TO COOLER OVERNIGHT LOWS,
AROUND 70.
SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/
KEY MESSAGE(S):
- COLD FRONT PUSHING THROUGH THE REGION WILL BRING UNSEASONABLY
COOL TEMPERATURES TO THE REGION
- RAIN CHANCES OVER THE REGION REMAIN HIGH BUT ARE UNCERTAIN
AND MODULATED BY HOW FAR SOUTH AND WEST THE SURFACE FRONT
MAKES IT
THE COLD FRONT IS GENERALLY FORECAST BY GUIDANCE TO BE PUSHING
THROUGH THE FORECAST AREA DURING THE DAY ON SATURDAY. SLOWLY BUT
SURELY, IT SHOULD BE IN THE SOUTHERN/WESTERN PORTION OF THE AREA BY
SUNDAY. COPIOUS MOISTURE IS STILL EXPECTED TO REMAIN ACROSS THE AREA
THROUGH THE DAY ON SATURDAY, AND WHILE OVERALL FLOW IN THE LOW-
LEVELS (THROUGH ~850 HPA AT LEAST) SHIFTS NORTHEASTERLY, THE
PRESENCE OF FRONTAL FORCING SHOULD AID IN RAIN SHOWERS PERSISTING AT
TIMES THROUGH THE DAY ON SATURDAY. HOW HEAVY AND WIDESPREAD THEY
WILL BE IS UP FOR DEBATE, AS THE SPREAD AMONGST GUIDANCE SOLUTIONS
IS ABNORMALLY HIGH FOR THIS RANGE. COVERAGE MAY BE SIMILAR TO TODAY
AND YESTERDAY BUT WIDESPREAD THUNDERSTORMS LOOK PRETTY UNLIKELY.
THERE MAY BE SOME HEAVIER RAIN IN SHOWERS ACROSS THE CSRA & SOUTHERN
MIDLANDS WITH EMBEDDED RUMBLES OF THUNDER AS WELL. BUT IN GENERAL,
THIS SHOULD BE MORE RAIN SHOWERS THAN IT HAS BEEN THIS WEEK. THE
BEST SENSIBLE WEATHER IMPACT SHOULD BE THE PRESENCE OF WELL BELOW
NORMAL TEMPS. CLOUD COVER IS EXPECTED MOST OF THE DAY, AND WITH
PERIODIC SHOWERS, HIGHS SHOULD ONLY GET INTO THE LOWER 80S. THE
FRONT IS FORECAST TO CONTINUE PUSHING SOUTH AND SOUTHWESTWARD
OVERNIGHT ON SATURDAY, WITH LOWS IN THE UPPER 60S/LOWER 70S.
BY EARLY SUNDAY, GUIDANCE REMAINS ALL OVER THE PLACE WITH RESPECT TO
WHERE THE SURFACE BOUNDARY WILL BE. THIS IS CRITICAL FOR SENSIBLE
WEATHER ON SUNDAY AND HEADING INTO NEXT WEEK, TOO, AS IT WILL
MODULATE RAIN CHANCES FOR MULTIPLE DAYS. THE ECMWF CONTINUES TO LOOK
LIKE AN OUTLIER, HANGING THE FRONT UP DIRECTLY IN THE CSRA AND
SOUTHERN MIDLANDS. MEANWHILE, THE NAM (WHICH HANDLES BACKDOOR FRONTS
WELL HISTORICALLY), GFS, AND CANADIAN ALL PUSH THE FRONT THROUGH THE
AREA BY SUNDAY, WITH IT STRETCHING FROM THE SC COASTAL PLAIN TO
SOUTH-CENTRAL GA. HOWEVER, EVEN THIS SOLUTION LEADS TO DIFFERENT
SENSIBLE WEATHER WITH THE CANADIAN SHOWING WIDESPREAD RAINFALL
ACROSS THE WESTERN FA SUNDAY ATOP THE SURFACE CAD SETUP. IN ADDITION
TO THE DIFFERENCE BETWEEN SURFACE FRONT PATTERNS, THERE IS A
SHORTWAVE ALOFT THAT SHOULD PUSH INTO THE TN VALLEY SUNDAY MORNING
THAT MODELS ARE HANDLING DIFFERENT. THE WETTER SOLUTIONS ARE
SLIGHTLY MORE AMPLIFIED WITH THE TROUGH, WHICH PLACES MORE OF A
STRONG RIGHT-ENTRANCE REGION OF THE UPPER LEVEL JET STREAK OVER US.
THIS WOULD INTRODUCE MORE ISENTROPIC LIFT TO THE REIGN AND LEAD TO
SHOWERS DEVELOPING THROUGH THE DAY ON SUNDAY. THE DRIER SOLUTIONS
ARE FLATTER AND FASTER WITH THE TROUGH, LEADING TO A LACK OF
ISENTROPIC LIFT. NOT TOTALLY CONFIDENT IN WHICH IS GOING TO WORK OUT
AS THE MODELS ARE SPLIT ON THIS. LEAN TOWARDS TRUSTING THE NAM GIVEN
ITS USUAL EXCELLENCE WITH CAD EVENTS BUT TRUSTING THE NAM IS A TOUGH
PLACE TO BE IN. REGARDLESS, THE BEST CHANCE FOR RAINFALL ON SUNDAY
CERTAINLY LOOKS TO BE ACROSS THE WESTERN/SOUTHERN MIDLANDS AND
CSRA, WITH THE POSSIBILITY THAT RAINFALL ENDS UP BEING MORE
WIDESPREAD THAN THAT. THE NORTHERN MIDLANDS COULD END UP WITH
QUITE THE NICE SUNDAY IF DRIER SOLUTIONS WORK OUT. REGARDLESS,
CLOUDS WILL CONTINUE TO BE AROUND AND SHOULD KEEP THINGS COOL.
TEMPERATURES CONTINUE TO LOOK WELL BELOW NORMAL, WITH UPPER 70S
AND LOW 80S EXPECTED. SIMILAR UNCERTAINTY AS TO HOW INTENSE
AND/OR WIDESPREAD PRECIP IS GOING INTO SUNDAY NIGHT, WITH LOWS
LIKELY IN THE UPPER 60S AND LOW 70S.
LONG TERM /MONDAY THROUGH THURSDAY/
KEY MESSAGE(S):
- CONFIDENCE IS RELATIVELY HIGH IN A COOL AND WET PERIOD THROUGH THE
MIDDLE OF NEXT WEEK.
IN GENERAL, THE LONG TERM DOES LOOK FAIRLY ACTIVE WITH THE SURFACE
CAD BOUNDARY SLOWLY LIFTING NORTHWARD AND BECOMING MORE DIFFUSE
THROUGH THE WEEK. AS IT DOES SO, A TROUGH IS EXPECTED TO CONTINUE
AMPLIFYING TO OUR WEST BY MIDWEEK, WITH PWS RETURNING BACK TO 1.9"+
RANGE FOR MOST OF THE WEEK. GIVEN THE TROUGH SETTING UP TO OUR WEST,
INCREASING MOISTURE, AND DIFFUSE FRONT RETURNING TOWARDS THE REGION,
SHORTWAVES ALOFT WILL HAVE AN EASY TIME INITIATING SHOWERS AND
STORMS EACH DAY. POPS SHOULD BE IN THE 45%-75% RANGE EACH AFTERNOON,
ABOVE NORMAL THIS TIME OF YEAR ESPECIALLY FOR THIS POINT IN THE
FORECAST. SO WHILE TEMPERATURES WILL LIKELY MODERATE INTO THE UPPER
80S, THIS WILL STILL BE A FEW DEGREES BELOW NORMAL ACROSS THE AREA
THROUGH THE WEEK. DEPENDING ON HOW MUCH RAIN FALLS WHERE THIS
WEEKEND INTO EARLY NEXT WEEK, WE'LL NEED TO BE INCREASINGLY AWARE OF
A FLASH FLOODING POSSIBILITY AS WE GET FURTHER INTO NEXT WEEK. WHILE
THE ECMWF AND ECE ARE THE WETTEST GUIDANCE, THE ECE EFI DOES POINT
TO HIGH QPF POTENTIAL IN THE CSRA DURING THE SAT-THUR TIMEFRAME,
WITH HIGH EFI VALUES AND A SHIFT-OF-TAILS OF ~1. SO WHILE THERE IS
UNCERTAINTY THROUGHOUT THE SHORT/LONG TERM, ITS LIKELY THAT SOMEONE
WILL END UP WITH QUITE A BIT OF RAINFALL IN THIS KIND OF
PATTERN.
AVIATION /18Z FRIDAY THROUGH WEDNESDAY/
STORMS EXPECTED THIS AFTERNOON AND EVENING WITH HIGHEST STORM
CHANCES IN THE CENTRAL AND EASTERN FA. RESTRICTIONS LIKELY
TONIGHT AS A FRONT WORKS INTO THE REGION.
SHOWERS AND STORMS WILL DEVELOP THIS AFTERNOON BUT APPEARS THAT
THE HIGHEST CHANCE FOR IMPACTS TO THE TERMINALS WILL BE THIS
EVENING AS MORE ORGANIZED CONVECTION WORKS ACROSS THE AREA.
IF STORMS IMPACT THE TAF SITES THEN THEY WILL LIKELY PRODUCE
HEAVY RAIN AND GUSTY ERRATIC WINDS. A COLD FRONT WILL MOVE INTO
THE AREA TONIGHT WITH BLENDED GUIDANCE INDICATING WIDESPREAD
STRATUS DEVELOPING OVER THE TERMINALS TOWARDS THE END OF THE TAF
PERIOD.
EXTENDED AVIATION OUTLOOK...A COLD FRONT OVER THE AREA WILL
BRING MORE WIDESPREAD RESTRICTIONS AND RAIN THIS WEEKEND.
CAE WATCHES/WARNINGS/ADVISORIES
SC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ018-022-
025>031-035-037-038-041-135>137. GA...HEAT ADVISORY UNTIL 8 PM
EDT THIS EVENING FOR GAZ040-063>065- 077.
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