253
FXUS62 KCAE 171033
AFDCAE
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE COLUMBIA SC
633 AM EDT FRI JUL 17 2026
WHAT HAS CHANGED
AVIATION UPDATED FOR 12Z TAF.
KEY MESSAGES
- 1. ISOLATED CONVECTION POSSIBLE TODAY WITH HOT/HUMID
TEMPERATURES AND HEAT INDICES NEAR 105F.
- 2. INCREASED CHANCES OF RAIN AND SEVERE WEATHER OVER THE
WEEKEND WITH HIGHEST CHANCES SUNDAY INTO MONDAY.
DISCUSSION
KEY MESSAGE 1: ISOLATED CONVECTION POSSIBLE TODAY WITH
HOT/HUMID TEMPERATURES AND HEAT INDICES NEAR 105F.
ANOTHER HOT/HUMID DAY IS IN STORE TODAY AS UPPER RIDGING
REMAINS IN PLACE. 850MB TEMPERATURES CURRENTLY NEAR 20C ARE
EXPECTED TO RISE A BIT FURTHER TOWARD 22C AND STRONG HEATING IS
EXPECTED TO BRING TEMPERATURES INTO THE MID TO UPPER 90S. DEEPER
MIXING IS EXPECTED TODAY, BUT DESPITE THIS, SURFACE DEWPOINTS
IN THE MID 70S MAY ONLY MIX OUT TOWARD THE LOWER 70S WITH 925MB
DEWPOINTS PROGGED TO BE NEAR 69-72F. THIS SHOULD BRING HEAT
INDICES ABOVE 100F BY THE LATE MORNING, WITH HEAT INDICES
PEAKING AROUND 105F DURING THE AFTERNOON. A COUPLE LOCATIONS
BRIEFLY REACHING 108F CANNOT BE RULED OUT, BUT CONFIDENCE IN
WIDESPREAD 108F HEAT INDICES IS LOW, THUS A HEAT ADVISORY WAS
NOT ISSUED WITH THIS FORECAST PACKAGE. THE OTHER POTENTIAL FLY
IN THE OINTMENT IS CONVECTION DURING THE AFTERNOON. THE MEAN
HREF SOLUTION AND HRRR KEEP COVERAGE RATHER ISOLATED AND MAINLY
CONFINED TOWARD THE SEA BREEZE LATER IN THE AFTERNOON, BUT WITH
CONVECTIVE TEMPERATURES BETWEEN 94-96F, I WOULD NOT BE SURPRISED
IF COVERAGE ENDS UP BEING A BIT MORE SCATTERED, AND GETS GOING
A BIT EARLIER THAN MODELED. IF THIS SCENARIO PANS OUT, AFTERNOON
HIGHS MAY END UP A BIT COOLER THAN FORECAST, BUT EITHER WAY,
HOT/HUMID CONDITIONS SHOULD BE EXPECTED TODAY.
WIDESPREAD SEVERE WEATHER IS NOT EXPECTED WITH TODAY'S ACTIVITY
AS GREATER MOISTURE AND KINEMATICS IS EXPECTED TO MOVE IN THIS
WEEKEND. WITH THAT SAID, STRONG HEATING AND DEWPOINTS IN THE 70S
SHOULD YIELD MUCAPE VALUES BETWEEN 2500-3000 J/KG. DEEPER
MIXING SHOULD ALSO YIELD DCAPE VALUES NEAR 1000 J/KG WITH TEI
VALUES BETWEEN 24-27. IF A STRONG UPDRAFT CAN ESTABLISH ITS SELF
IN THIS WEAKLY SHEARED ENVIRONMENT, AN ISOLATED STRONGER STORM
WITH THE RISK OF GUSTY DOWNBURST WINDS.
KEY MESSAGE 2: INCREASED CHANCES OF RAIN AND SEVERE WEATHER
OVER THE WEEKEND WITH HIGHEST CHANCES SUNDAY INTO MONDAY.
THERE HAS NOT BEEN A SIGNIFICANT SHIFT IN THE OUTLOOK HEADING
INTO THIS WEEKEND AND EARLY NEXT WEEK. SUBTLE MID LEVEL HEIGHT
FALLS ARE PROGGED TO OCCUR SATURDAY AS A DEEPENING TROUGH MOVES
INTO THE GREAT LAKES. STRENGTHENING MOISTURE ADVECTION IS ALSO
EXPECTED AS A DEVELOPING WEAK TROPICAL DISTURBANCE IN THE
NORTHEASTERN GULF BRINGS PWAT'S ABOVE 2". THIS SHOULD YIELD
RELATIVELY WEAK, BUT SUFFICIENT FORCING FOR SCATTERED CONVECTION
DURING THE AFTERNOON/EVENING SATURDAY. OVERALL, A FAIRLY
TYPICAL STRONG TO MARGINALLY SEVERE PULSE ENVIRONMENT IS
EXPECTED TO DEVELOP AS MUCAPE VALUES IN THE 00Z HREF REMAIN NEAR
2500 J/KG, BUT EVEN DEEPER MIXING MAY YIELD DCAPE VALUES NEAR
1200 J/KG. ISOLATED MICROBURSTS AND THE ASSOCIATED DAMAGING WIND
RISK WOULD BE THE MAIN CONCERN. WITH FAIRLY WEAK KINEMATICS
STILL IN PLACE, MEAN STORM MOTIONS ARE EXPECTED TO BE NEAR
10KTS, BRINGING A LOCALLY HEAVY RAINFALL RISK AS WELL.
GREATER HEIGHT FALLS ARE SHOWN IN ENSEMBLE GUIDANCE SUNDAY AND
MONDAY AS THE UPPER TROUGH DEEPENS A BIT. AT THIS POINT, PWAT'S
ARE EXPECTED TO RISE UP NEAR 2.10-2.20" WITH THE WEAK LOW LEVEL
CIRCULATION IN THE NORTHEASTERN GULF BECOMING A BIT MORE
COLLECTED. THERE SHOULD ALSO BE ENHANCED SURFACE TROUGHING OVER
THE REGION, YIELDING SOLID MOISTURE CONVERGENCE. CLOUD LAYER
SHEAR AROUND 30-35 KTS IS EXPECTED ON SUNDAY, POSSIBLY BRINGING
BETTER STORM ORGANIZATION DURING THE AFTERNOON/EVENING AS LREF
PROBABILITIES FOR SBCAPE OVER 2000 J/KG ARE NEAR 50%. THIS COULD
YIELD A GREATER SEVERE RISK (MAINLY IN FORM OF DAMAGING WINDS)
WITH THE AREA REMAINING IN SPC'S SLIGHT RISK (LEVEL 2 OUT OF 5).
AI/ML GUIDANCE HINT A COUPLE STRONG TO MARGINALLY SEVERE STORMS
COULD BE POSSIBLE AGAIN ON MONDAY AS THE WEAK TROPICAL
DISTURBANCE SLOWLY DRIFTS NORTHEASTWARD, BUT THERE IS STILL
GENEROUS UNCERTAINTY IN THE EVOLUTION OF THIS DISTURBANCE. HEAVY
RAINFALL COULD ALSO ACCOMPANY THIS ACTIVITY EACH DAY WITH THE
DEEP MOISTURE IN PLACE AND FAIRLY LONG/SKINNY CAPE PROFILES.
AVIATION /12Z FRIDAY THROUGH TUESDAY/
SCATTERED AFTERNOON STORMS MAY LEAD TO BRIEF RESTRICTIONS BUT
OTHERWISE VFR.
VFR CONDITIONS IN PLACE AT ALL TERMINALS WITH LIGHT AND VARIABLE
WINDS. WINDS GENERALLY EXPECTED TO REMAIN LIGHT, OUT OF THE
SOUTH AROUND 5 KNOTS. SCATTERED THUNDERSTORMS EXPECTED TO
DEVELOP THIS AFTERNOON INTO EVENING WITH GREATER COVERAGE THAN
YESTERDAY. PROBABILITY REMAINS AROUND 30 PERCENT OF STORMS
IMPACTING THE TERMINALS SO HAVE INCLUDED PROB30 MENTION FROM
19-00Z.
EXTENDED AVIATION OUTLOOK...POTENTIAL FOR RESTRICTIONS FROM
SHOWERS AND THUNDERSTORMS CONTINUE THIS WEEKEND INTO EARLY NEXT
WEEK.
CAE WATCHES/WARNINGS/ADVISORIES
SC...AIR QUALITY ALERT FROM 10 AM THIS MORNING TO 8 PM EDT THIS
EVENING FOR SCZ115-116.
GA...NONE.
DISCUSSION...DH
AVIATION...96
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