571
FXUS62 KCAE 180623
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
223 AM EDT SAT JUL 18 2026
WHAT HAS CHANGED
HEAT ADVISORY ISSUED ALONG AND SOUTH OF
THE I-20 CORRIDOR TODAY. CONVECTIVE COVERAGE THIS AFTERNOON HAS
TRENDED A BIT LOWER. AVIATION DISCUSSION UPDATED FOR 06Z TAFS.
KEY MESSAGES
- 1. HEAT ADVISORY IN EFFECT FROM 12 PM TO 8 PM ALONG AND SOUTH
OF THE I-20 CORRIDOR AS HEAT INDICES REACH BETWEEN 105-108F.
ISOLATED TO SCATTERED CONVECTION EXPECTED WITH A COUPLE STRONG
TO SEVERE STORMS POSSIBLE THIS AFTERNOON/EVENING.
- 2. MORE THUNDERSTORM CHANCES SUNDAY INTO MONDAY WITH POSSIBLE
SEVERE THUNDERSTORMS. ANOTHER CHANCE FOR STRONG CONVECTION
POSSIBLE DURING THE MIDWEEK.
DISCUSSION
KEY MESSAGE 1: HEAT ADVISORY IN EFFECT FROM 12 PM TO 8 PM ALONG
AND SOUTH OF THE I-20 CORRIDOR AS HEAT INDICES REACH BETWEEN
105-108F. ISOLATED TO SCATTERED CONVECTION EXPECTED WITH A
COUPLE STRONG TO SEVERE STORMS POSSIBLE THIS AFTERNOON/EVENING.
THE MAIN CHANGE TODAY IS A HEAT ADVISORY WILL BE IN EFFECT
ALONG AND SOUTH OF THE I-20 CORRIDOR FROM NOON TO 8 PM. THIS
COMES AS RECENT TRENDS HAVE BEEN TOWARD KEEPING SURFACE
DEWPOINTS IN THE LOW TO MID 70S THROUGH THE DAY TODAY WITH
MINIMAL MIXING OUT. THIS IS MAINLY DUE TO 925MB DEWPOINTS
REMAINING NEAR 70-72F TODAY. TEMPERATURES SHOULD ONCE AGAIN
REACH THE MID TO UPPER 90S AND THUS HEAT INDICES ARE EXPECTED TO
REACH AS HIGH AS 108F IN THE ADVISORY AREA. THE 00Z SUITE OF
CAMS AND THE 00Z HREF DEPICT FAIRLY SIMILAR CONVECTIVE COVERAGE
AS TODAY, GIVING INCREASED CONFIDENCE IN REALIZING ADVISORY
LEVEL HEAT INDICES. BE SURE TO TAKE HEAT SAFETY PRECAUTIONS
TODAY WITH ANY OUTDOOR ACTIVITY!
AS MENTIONED ABOVE, CONVECTIVE COVERAGE THIS AFTERNOON/EVENING
HAS TREND A BIT SIMILAR TO THAT SEEN YESTERDAY. THIS COMES AS
BUFKIT SOUNDINGS INDICATE LINGERING MID-LEVEL CAPPING SHOULD
HOLD ON INTO THE EARLY AFTERNOON BEFORE A COMBINATION OF
INCREASED SURFACE TROUGHING AND THE SEA BREEZE INITIATE DEEPER
CONVECTION LATE IN THE AFTERNOON AND INTO THE EVENING HOURS.
UPPER SUPPORT REMAINS VERY MEAGER WITH EFFECTIVE SHEAR VALUES
UNDER 10 KTS, BUT STRONG INSTABILITY IS STILL PROGGED TO DEVELOP
(SBCAPE NEAR 3000 J/KG) IN THIS VERY MOIST ENVIRONMENT. A
COUPLE STRONG TO SEVERE STORMS WILL BE POSSIBLE AS ROBUST DCAPE
VALUES BETWEEN 1000-1300 J/KG, 3KM CAPE NEAR 100 J/KG, AND TEI
VALUES BETWEEN 25-30 BRING AN INCREASED RISK FOR STRONG
DOWNBURSTS AND THE ASSOCIATED DAMAGING WIND RISK. DUE TO THIS,
PORTIONS OF THE FA ARE IN SPC'S MARGINAL RISK (LEVEL 1 OUT OF 5)
FOR SEVERE WEATHER TODAY.
KEY MESSAGE 2: MORE THUNDERSTORM CHANCES SUNDAY INTO MONDAY
WITH POSSIBLE SEVERE THUNDERSTORMS. ANOTHER CHANCE FOR STRONG
CONVECTION POSSIBLE DURING THE MIDWEEK.
AS HAS BEEN DISCUSSED, A DEEPENING SHORTWAVE IS PROGGED TO MOVE
INTO THE MID-ATLANTIC THROUGH THE DAY SUNDAY, DRAGGING A
SURFACE FRONT THAT COULD NEAR THE PEE DEE SUNDAY NIGHT. ENHANCED
MOISTURE ADVECTION IS SHOWN ACROSS GUIDANCE AHEAD OF THESE
FEATURES WITH PWAT'S REACHING ABOVE 2", PARTLY THANKS TO GULF
MOISTURE BEING TRANSPORTED NORTHWARD ON THE EASTERN PERIPHERY OF
A DEVELOPING WEAK TROPICAL DISTURBANCE IN THE NORTHEASTERN
GULF. OVERALL, THE ENVIRONMENT IS NOT EXPECTED TO BE ALL THAT
DIFFERENT FROM THE LAST COUPLE OF DAYS, FAVORING A DAMAGING WIND
RISK FROM PRECIP-LOADED DOWNDRAFTS. THE MAIN DIFFERENCE IS
MARGINAL UPPER SUPPORT SHOULD BRING INCREASED COVERAGE AND
EFFECTIVE SHEAR VALUES NEAR 10-15 KTS, ESPECIALLY TOWARD THE PEE
DEE, WHICH COULD AID IN BETTER ORGANIZATION OF A FEW CLUSTERS.
THIS HAS RESULTED IN MOST OF THE FA REMAINING IN A MARGINAL RISK
FOR SEVERE WEATHER, BUT A SLIGHT RISK (LEVEL 2 OUT OF 5) STILL
SCRAPES THE PEE DEE WITH THE GREATER SHEAR HERE. THE FRONTAL
BOUNDARY IS EXPECTED TO REMAIN NEAR THE PEE DEE INTO MONDAY WITH
WEAK SHORTWAVE ENERGY PASSING THROUGH THE REGION, BRINGING
ANOTHER DAY WITH INCREASED AFTERNOON CONVECTIVE COVERAGE AND THE
CHANCE FOR A COUPLE STRONG TO MARGINALLY SEVERE STORMS.
THE EC ENSEMBLE AND GOOGLE DEEPMIND HAVE TRENDED MORE TOWARDS
THE WEAK TROPICAL DISTURBANCE MEANDERING THROUGH THE
NORTHEASTERN GULF EARLY IN THE WEEK BEFORE SLOWLY DRIFTING
WESTWARD INTO THE MID WEEK. THIS SHOULD STILL ALLOW DEEP
MOISTURE TO ADVECT INTO THE REGION FROM THE SOUTH, BUT BOTH
ENSEMBLE AND DETERMINISTIC GUIDANCE HAVE DISPLAYED INCREASED
CONFIDENCE THAT AN EVEN SHARPER SHORTWAVE SHOULD DIG INTO THE
EASTERN CONUS DURING THE MID-WEEK, POSSIBLY DRAGGING ANOTHER
FRONTAL BOUNDARY NEAR THE FA. ENHANCED KINEMATICS COUPLED WITH
SEASONABLE TO STRONG INSTABILITY COULD BRING ANOTHER CHANCE FOR
STRONGER CONVECTION DURING THE MIDWEEK AS HIGHLIGHTED IN
CSU/CIPS/NCAR MACHINE LEARNING AND AI GUIDANCE. TIMING
DIFFERENCE STILL NEED TO BE SORTED OUT ACROSS DETERMINISTIC
GUIDANCE, BUT THE PATTERN SEEMS FAVORABLE FOR POTENTIAL SEVERE
WEATHER AGAIN.
AVIATION /06Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS EXPECTED FOR MUCH OF THE PERIOD WITH BRIEF
RESTRICTIONS POSSIBLE EARLY MORNING AND IN STORMS.
VFR CONDITIONS ARE IN PLACE AT ALL TERMINALS AS CONVECTION HAS
DIMINISHED ACROSS THE AREA. WHILE VFR CONDITIONS ARE GENERALLY
EXPECTED TO CONTINUE, INCREASED LOW LEVEL MOISTURE MAY LEAD TO BRIEF
RESTRICTIONS, GENERALLY AT OGB AND AGS, ALTHOUGH MODELS ARE NOT
OVERWHELMINGLY POINTING TO THIS SOLUTION. ANY RESTRICTIONS SHOULD
DISSIPATE SHORTLY AFTER SUNRISE WITH VFR CONDITIONS AS SCATTERED
CUMULUS AROUND 5KFT DEVELOP. WINDS INCREASING OUT OF THE SOUTH,
GENERALLY BETWEEN 5 TO 10 KNOTS. SCATTERED THUNDERSTORMS DEVELOP
LATE THIS AFTERNOON INTO EVENING SO HAVE INCLUDED A PROB30 GROUP TO
ACCOUNT FOR INCREASING STORM COVERAGE.
EXTENDED AVIATION OUTLOOK...POTENTIAL FOR RESTRICTIONS FROM SHOWERS
AND THUNDERSTORMS CONTINUES INTO NEXT WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
SCZ016-022-027>031-035-037-038-041-135>137.
GA...HEAT ADVISORY FROM NOON TODAY TO 8 PM EDT THIS EVENING FOR
GAZ063>065-077.
DISCUSSION...DH
AVIATION...96
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