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FXUS62 KCHS 051811
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
211 PM EDT TUE MAY 5 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 18Z TAF ISSUANCE.
KEY MESSAGES
- 1) A COLD FRONT WILL BRING AN INCREASED RISK FOR SHOWERS AND
THUNDERSTORMS TO THE REGION THURSDAY INTO SATURDAY.
DISCUSSION
KEY MESSAGE 1: A COLD FRONT WILL BRING AN INCREASED RISK FOR SHOWERS
AND THUNDERSTORMS TO THE REGION THURSDAY INTO SATURDAY.
HIGH PRESSURE ACROSS THE ATLANTIC WILL CONTINUE TO YIELD LIGHT
SOUTHERLY WINDS ACROSS THE EASTERN SEABOARD, WHILE AN UPPER-LVL
TROUGH SCOOTS ACROSS THE GREAT LAKES. EXPECT THIS TROUGH MOVE INTO
THE LOWER MISSISSIPPI VALLEY BY WEDNESDAY. SIMULTANEOUSLY, AN
ASSOCIATED COLD FRONT WILL MARCH ACROSS THE CENTRAL GULF STATES ON
WEDNESDAY, AND THEN INTO THE SOUTHEAST ON THURSDAY NIGHT. THIS WILL
LEAD TO SCATTERED SHOWERS AND THUNDERSTORMS AS THE FRONT APPROACHES
ON THURSDAY.
AHEAD OF THE FRONT, A SEASONABLY MOIST AIRMASS FROM THE GULF WILL
ADVECT INTO THE REGION WITH PWATS RANGING 1.8 TO 2.0 INCHES. ALONG
WITH THIS RICH MOISTURE, THE KINEMATIC ENVIRONMENT REMAINS FAVORABLE
FOR STRONG TO SEVERE THUNDERSTORMS ON THURSDAY. MODERATE 0-3KM SHEAR
(250-300 M^2/S^2) COUPLED WITH STRONG DEEP-LAYER FLOW COULD AID TO
THE SEVERITY OF THURSDAY. THE LIMITING ENVIRONMENTAL FACTOR REMAINS
TO BE THE CLOUD COVER AHEAD OF THE FRONT AS THIS MIGHT TEMPER
DESTABILIZATION, HOWEVER IF THERE ARE SOME BREAKS IN CLOUD COVER,
POCKETS OF STRONGER DAYTIME HEATING COULD YIELD MODEST MLCAPE VALUES.
THE STORM PREDICTION CENTER (SPC) HAS HIGHLIGHTED THE ENTIRE REGION
IN A MARGINAL RISK (1/5) FOR SEVERE THUNDERSTORMS ON THURSDAY. THE
PRIMARY THREAT WILL BE ISOLATED DAMAGING WING GUSTS WITHIN
THUNDERSTORMS THAT EVOLVE, WITH LOCALLY HEAVY POCKETS OF RAINFALL
POSSIBLE GIVEN THE ANOMALOUSLY MOIST ENVIRONMENT.
HOWEVER, SUBSTANTIAL UNCERTAINTY REMAINS IN REGARDS TO THE PHASING
OF THE UPPER-LVL TROUGH AND IT'S INTERACTION WITH THE UPPER-LVL
CLOSED LOW SITUATED ACROSS SOUTHERN CALIFORNIA. WITH THE LATEST
GUIDANCE, THE FRONT REMAINS TO BE ON THE PROGRESSIVE SIDE OF THE HI-
RES GUIDANCE AS THE 12Z HRRR INDICATES MOST OF THE SHOWER AND
THUNDERSTORM ACTIVITY WILL TRANSPIRE IN THE EARLY MORNING HOURS ON
THURSDAY. THIS MATCHES WELL WITH THE 12Z GFS AS IT SUGGESTS A MORE
PROGRESSIVE SOLUTION AS WELL. AS OF RIGHT NOW, IT SEEMS LIKE THIS
WILL BE THE MORE LIKELY SOLUTION, HOWEVER MODEL GUIDANCE REMAINS
STILL SPLIT WITH THE 06Z ECMWF DISPLAYING A LESS PROGRESSIVE
SOLUTION (W/ AN AFTERNOON ARRIVAL OF CONVECTION). A MORE PROGRESSIVE
SOLUTION WOULD REDUCE THE SEVERE RISK, WHILE A SLOWER SOLUTION
COUPLED WITH GOOD AFTERNOON HEATING WOULD SUPPORT A HIGHER RISK.
THUS, FORECAST CONFIDENCE REMAINS LOW AS THE SEVERE THREAT IS
DEPENDENT ON THE FRONTAL TIMING AND THE DEGREE OF DESTABILIZATION
THAT TAKES PLACE AHEAD OF THE FRONT. REGARDLESS, THE FRONT SHOULD
PUSH OFFSHORE OVERNIGHT ON THURSDAY AS DRIER, MORE STABLE AIR
FILTERS IN BEHIND IT.
AVIATION /18Z TUESDAY THROUGH SUNDAY/
18Z TAFS: VFR CONDITIONS WILL PREVAIL AT CHS/JZI/SAV TERMINALS
THROUGH 18Z WEDNESDAY. IT'S IMPORTANT TO NOTE THAT BREEZY SOUTH-
SOUTHEASTERLY WINDS (NEAR 20-22 KT) WAS MAINTAINED FOR ALL TERMINALS
THIS AFTERNOON.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS FROM SHOWERS AND
THUNDERSTORMS ARE POSSIBLE THURSDAY AND FRIDAY AS A COLD FRONT
PASSES THROUGH THE REGION.
MARINE
THROUGH TONIGHT: AS SURFACE HIGH PRESSURE SITUATES ITSELF ACROSS THE
ATLANTIC, EXPECT LIGHT SOUTH-SOUTHEASTERLY WINDS TO PREVAIL. EXPECT
LIGHT NORTH-NORTHEASTERLY WINDS TO BECOME MORE SOUTHERLY OVERNIGHT.
OTHERWISE, MARINE CONDITIONS SHOULD BE QUITE TRANQUIL WITH SEAS
RANGING FROM 2 TO 3 FT.
WEDNESDAY THROUGH SUNDAY: AHEAD OF AN APPROACHING COLD FRONT, THE
PRESSURE GRADIENT WILL BECOME PINCHED ON WEDNESDAY, LEADING TO
MARGINALLY BREEZY SOUTH-SOUTHEASTERLY WINDS. HEADING INTO THURSDAY
(AS THE FRONT INCHES CLOSER), WINDS WILL BECOME BREEZIER WITH MODELS
SUPPORTING GUSTS UP TO 22-23 KTS THROUGH THURSDAY EVENING ACROSS THE
MOST OF THE LOCAL WATERS. SIMULTANEOUSLY, SEAS SHOULD GRADUALLY
BUILD TO 3-5 FT ACROSS THE SOUTH CAROLINA WATERS AND 3-4 FT ACROSS
THE GEORGIA WATERS. SMALL CRAFT ADVISORY CONDITIONS REMAIN BORDERLINE
ACROSS THE NEARSHORE CHARLESTON WATERS ON THURSDAY, AND THIS WILL
CONTINUE TO BE MONITORED. AFTER THE FRONT PUSHES OFFSHORE, MARINE
CONDITIONS SHOULD STABILIZE OVERNIGHT ON THURSDAY INTO THE
WEEKEND.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
DENNIS
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