660
FXUS62 KCHS 201055
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
655 AM EDT SAT JUN 20 2026
WHAT HAS CHANGED
ALL SECTIONS AND KEY MESSAGES HAVE BEEN UPDATED.M
KEY MESSAGES
- 1) RISK FOR HEAVY RAIN AND FLOODING THIS AFTERNOON ACROSS
PARTS OF SOUTHEAST GEORGIA.
- 2) A FAIRLY TYPICAL SUMMERTIME PATTERN IS EXPECTED THROUGH
THE MIDDLE OF NEXT WEEK WITH DAILY SHOWER AND THUNDERSTORM
CHANCES.
- 3) HOT AND HUMID CONDITIONS LIKELY TO PEAK MONDAY AND
TUESDAY. HEAT ADVISORIES COULD BE NEEDED.
DISCUSSION
KEY MESSAGE 1: RISK FOR HEAVY RAIN AND FLOODING THIS AFTERNOON
ACROSS PARTS OF SOUTHEAST GEORGIA.
WEAK CYCLONIC FLOW WILL REMAIN IN PLACE ACROSS THE SOUTHEAST
U.S. TODAY AS A SERIES OF SHORTWAVES PROPAGATE EASTWARD ACROSS
THE OHIO VALLEY INTO THE NORTHEAST STATES AND MID-ATLANTIC
REGION. A WEAK BACKDOOR COLD FRONT WILL DROP SOUTH INTO THE
AREA LATER THIS MORNING AND BECOME STATIONARY NEAR THE I-16
CORRIDOR LATER THIS AFTERNOON AS IT BECOMES INCREASINGLY
INTERMINGLED WITH THE SEA BREEZE. A PRONOUNCED CHANGE IN AIRMASS
WILL OCCUR BEHIND THE FRONT WITH AN INCREASINGLY DRIER AND
CAPPED ENVIRONMENT ADVECTING SOUTH INTO THE SOUTH CAROLINA
LOWCOUNTRY. SOUTH OF THE FRONT, WARM AND HUMID CONDITIONS WILL
PERSIST WITH PWATS HOLDING ABOVE 2 INCHES AND DEWPOINTS IN THE
LOWER-MID 70S.
20/00Z GUIDANCE IS SIMILAR IN SHOWING WEAK UPPER FORCING
OCCURRING LATER THIS AFTERNOON A REGION OF WEAK CHANNELED
VORTICITY PROPAGATING EAST ALONG THE NORTHERN GULF COAST MOVES
INTO SOUTHEAST GEORGIA. THIS COUPLED WITH BUILDING INSTABILITY
(MLCAPE 2000-2500 J/KG) AND LOW-LEVEL CONVERGENCE IN THE
VICINITY OF BOTH THE FRONT ITSELF AND THE SEA BREEZE SHOULD
SUPPORT ISOLATED TO SCATTERED SHOWERS/TSTMS ACROSS FAR SOUTHERN
SOUTH CAROLINA WITH SCATTERED TO WIDESPREAD SHOWERS/TSTMS ACROSS
PARTS OF SOUTHEAST GEORGIA. THE HIGHEST COVERAGE LOOKS TO OCCUR
NEAR ALTAMAHA RIVER WHERE MOISTURE, LIFT AND INSTABILITY WILL
BE MAXIMIZED. 850-300 HPA FLOW LOOKS TO REMAIN FAIRLY MODEST
(20-25 KT) SO STORMS SHOULD REMAIN FAIRLY PROGRESSIVE; HOWEVER,
GIVEN THE DEGREE OF PWATS THERE IS AN ELEVATED POTENTIAL FOR
TORRENTIAL RAINFALL WITH A RISK FOR ISOLATED FLASH FLOODING
ACROSS PARTS OF TATTNALL, LONG AND MCINTOSH COUNTIES WHERE 3-HR
NEIGHBORHOOD PROBABILITIES FOR >3" ARE RUNNING 30-35%. AT THIS
TIME, THE RISK FOR MORE SIGNIFICANT FLASH FLOODING LOOKS TO
REMAIN DISPLACED SOUTH OF THE ALTAMAHA RIVER WHERE AS MUCH AS
4-10" OF RAIN HAVE FALLEN OVER THE PAST 24-36 HRS. WFO
JACKSONVILLE HAS ISSUED A FLOOD WATCH FOR THAT PART OF SOUTHEAST
GEORGIA AS A RESULT. A FLOOD WATCH WILL NOT BE ISSUED FOR
TATTNALL, LONG AND MCINTOSH COUNTIES AT THIS TIME GIVEN THIS
AREA HAS OBSERVED CONSIDERABLY LESS RAIN, BUT THIS WILL BE
CAREFULLY MONITORED THROUGHOUT THE DAY. IN ADDITION TO HEAVY
RAIN, AN ISOLATED STRONG/SEVERE TSTM OR TWO CAN NOT BE RULED
OUT WITH LOCALIZED STRONG/DAMAGING WIND GUSTS AND FREQUENT
CLOUD-TO-GROUND LIGHTNING BEING THE PRIMARY NON-RAIN HAZARDS.
CONVECTION WILL QUICKLY WIND DOWN THIS EVENING WITH A RISK FOR
ISOLATED CONVECTION LINGERING ACROSS PARTS OF SOUTHEAST GEORGIA
THROUGH LATE EVENING.
HIGHS TODAY WILL WARM INTO THE UPPER 80S/LOWER 90S. HEAT INDICES
COULD PEAK IN THE 100-104 RANGE ACROSS SOUTH OF A REIDSVILLE-
BEAUFORT LINE BEFORE THE ONSET OF CONVECTION. OVERNIGHT LOWS
WILL RANGE FROM THE UPPER 60S/NEAR 70 WELL INLAND TO THE MID-
UPPER 70S AT THE BEACHES AND DOWNTOWN CHARLESTON.
KEY MESSAGE 2: A FAIRLY TYPICAL SUMMERTIME PATTERN IS EXPECTED
THROUGH THE MIDDLE OF NEXT WEEK WITH DAILY SHOWER AND
THUNDERSTORM CHANCES.
THE FORECAST AREA WILL BECOME POSITIONED BETWEEN HIGH PRESSURE
OFFSHORE AND AN APPROACHING COLD FRONT EARLY NEXT WEEK, BEFORE
FORECAST TO STALL NEAR OR OVER THE AREA MIDWEEK. ALOFT, A SERIES
OF WEAK DISTURBANCES WILL CROSS THE SOUTHEAST, BEFORE LARGER
SCALE TROUGHING POSSIBLY SETTLES INTO THE EASTERN CONUS.
ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE BOTH SUNDAY AND
MONDAY, WITH COVERAGE INCREASING TUESDAY THROUGH AT LEAST
THURSDAY. SHOWERS AND THUNDERSTORMS ARE EXPECTED TO PEAK IN THE
AFTERNOON AND EVENINGS WHEN INSTABILITY IS HIGHEST. AT THIS
TIME, THE THREAT FOR ORGANIZED SEVERE WEATHER IS LOW, BUT CANNOT
RULE OUT A COUPLE OF STRONG TO SEVERE STORMS, ESPECIALLY
TUESDAY ONWARD.
KEY MESSAGE 3: HOT AND HUMID CONDITIONS LIKELY TO PEAK MONDAY
AND TUESDAY. HEAT ADVISORIES COULD BE NEEDED.
ALREADY HOT AND HUMID CONDITIONS WILL INTENSIFY MONDAY AND
TUESDAY AS A RIDGE ALOFT STRENGTHENS ACROSS THE SOUTHERN CONUS
AND WESTERN ATLANTIC. HIGH TEMPERATURES ARE FORECAST TO REACH
THE LOW TO MID 90S ON MONDAY, WITH TEMPERATURES CLIMBING A FEW
DEGREES HIGHER ON TUESDAY. SOME LOCATIONS COULD APPROACH OR
EXCEED THE UPPER 90S TUESDAY AFTERNOON. COMBINED WITH DEW POINTS
IN THE 70S, HEAT INDEX VALUES COULD REACH 105-110F ON MONDAY,
ESPECIALLY ACROSS THE COASTAL COUNTIES. CONFIDENCE IS HIGHER ON
TUESDAY, WHEN MORE WIDESPREAD HEAT INDICES ABOVE 105F ARE
EXPECTED. A FEW LOCATIONS COULD REACH MAX HEAT INDICES BETWEEN
110-113F. LITTLE OVERNIGHT RELIEF IS EXPECTED MONDAY AND
TUESDAY, PARTICULARLY NEAR THE COAST, WHERE MINIMUM TEMPERATURES
COULD ONLY FALL INTO THE UPPER 70S TO LOWER 80S. IN ADDITION,
NWS HEATRISK GUIDANCE INDICATES A MAJOR RISK (LEVEL 3 OF 4)
ACROSS PORTIONS OF THE AREA. GIVEN THE COMBINATION OF EXTREME
HEAT, HIGH HUMIDITY, AND LIMITED NIGHTTIME COOLING, HEAT
ADVISORIES COULD BE NEEDED WHERE HEAT INDICES MEET OR EXCEED OUR
LOCAL CRITERIA OF 108F DEGREES. FORECAST TRENDS WILL CONTINUE
TO BE MONITORED OVER THE COMING DAYS.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
20/12Z TAF DISCUSSION:
KCHS/KJZI: IFR/MVFR CIGS ARE EXPECTED TO LIFT BY MID-MORNING
WITH VFR PREVAILING THROUGH THE REMAINDER OF THE 12Z TAF CYCLE.
KSAV: LIFR/IFR CIGS WILL STEADILY IMPROVE NOW THAT THE SUN IS
UP. VFR CIGS SHOULD RETURN BY MID-MORNING CONVECTION MAY BEGIN
TO POP NEAR THE TERMINAL LATE AFTERNOON, BUT THE GREATEST
COVERAGE SHOULD REMAIN WELL TO THE SOUTH. PROB30 FOR MVFR
CONDITIONS IN TSRA WAS INCLUDED 22-02Z FOR NOW.
EXTENDED AVIATION OUTLOOK: BRIEF PERIODS OF FLIGHT RESTRICTIONS
POSSIBLE WITH ANY SHOWERS AND THUNDERSTORMS.
MARINE
THROUGH TONIGHT: A WEAK BACKDOOR FRONT WILL STALL ACROSS
SOUTHEAST GEORGIA AND THE NEARBY ATLANTIC WATERS TODAY. WIND
FIELDS WILL BECOME A BIT CHAOTIC LATER IN THE DAY AS THE
AFTERNOON SEA BREEZE DEVELOPS AND INTERMINGLES WITH THE FRONT.
SPEEDS SHOULD REMAIN 10 KT OR LESS. SOUTHWEST WINDS WILL TURN
MORE WESTERLY OVERNIGHT WITH SPEEDS GENERALLY LESS THAN 10 KT.
SEAS OF 2-4 FT THIS MORNING WILL SUBSIDE TO 1-3 FT BY THIS
AFTERNOON WITH 1-2 FT OVERNIGHT. TSTMS COULD PRODUCE WIND GUSTS
IN EXCESS OF 34 KT ACROSS MAINLY THE GEORGIA AND FAR SOUTHERN
SOUTH CAROLINA WATERS THIS AFTERNOON/EVENING. A FEW SPECIAL
MARINE WARNINGS MAY BE NEEDED.
SUNDAY THROUGH THURSDAY: NO MARINE CONCERNS ARE EXPECTED
SUNDAY. THE COASTAL WATERS WILL BECOME POSITIONED BETWEEN HIGH
PRESSURE CENTERED WELL OFFSHORE AND AN APPROACHING COLD FRONT
MONDAY AND TUESDAY, LEADING TO INCREASING WINDS AND BUILDING
SEAS. GUSTS COULD APPROACH 25 KNOTS AT TIMES ESPECIALLY IN THE
AFTERNOONS, BUT LOOKS FAIRLY MARGINAL FOR SMALL CRAFT ADVISORIES
AT THIS TIME. CONDITIONS SHOULD STAY BELOW ADVISORY LEVELS
THROUGH THURSDAY.
CLIMATE
RECORD HIGH MINIMUM TEMPERATURES:
JUNE 23:
KCHS: 78/2024
KCXM: 82/1998
KSAV: 77/2017
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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