142
FXUS62 KCHS 290642
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
242 AM EDT MON JUN 29 2026
WHAT HAS CHANGED
ALL SECTIONS HAVE BEEN UPDATED.
KEY MESSAGES
- 1) HOT AND HUMID CONDITIONS ARE EXPECTED TO OCCUR AGAIN
TODAY. A HEAT ADVISORY IS IN EFFECT FOR PORTIONS OF THE AREA.
- 2) HIGH TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL ON
TUESDAY, THEN GRADUALLY RISING THROUGH THE HOLIDAY WEEKEND.
HEAT ADVISORIES COULD BE NEEDED DURING THE HOLIDAY WEEKEND
ACROSS PORTIONS OF OUR AREA.
DISCUSSION
KEY MESSAGE 1: HOT AND HUMID CONDITIONS ARE EXPECTED TO OCCUR
AGAIN TODAY. A HEAT ADVISORY IS IN EFFECT FOR PORTIONS OF THE
AREA.
ALOFT, THE FORECAST AREA WILL CONTINUE TO SIT ON THE EASTERN
PERIPHERY OF PROMINENT UPPER RIDGING AND AN ANTICYCLONE THAT
WILL LIFT INTO THE TN VALLEY. AT THE SURFACE, A WEAK BOUNDARY
WILL PUSH SOUTHWARD ACROSS THE AREA AS HIGH PRESSURE CENTERED
OFF THE NEW ENGLAND COAST ATTEMPTS TO NOSE SOUTHWARD. THE
SURFACE FLOW PATTERN WILL BE CONSIDERABLY DIFFERENT THAN IT WAS
YESTERDAY, MUCH WEAKER AND BEGINNING THE DAY LIGHT AND OUT OF
THE NORTH-NORTHWEST. WINDS SHOULD THEN REMAIN RATHER WEAK AND
OUT OF THE NORTHWEST FOR MUCH OF THE AREA, EXCEPT ALONG THE
COAST WHERE THE SEA BREEZE WILL START TO TAKE OVER IN THE
AFTERNOON. THE RESULT IS A SETUP THAT WON'T FAVOR AS MUCH MIXING
OUT OF DEWPOINTS AND ALLOW FOR GREATER COVERAGE OF LOW TO MID
70S VALUES, ESPECIALLY ALONG THE COAST AND ALONG AND SOUTH OF
I-16. THIS SHOULD CROSSOVER WELL WITH EXPECTED TEMPERATURES AND
PROVIDE THE BEST CHANCE OF SEEING HEAT INDEX VALUES REACHING 108
DEGREES IN THESE AREAS. OUTSIDE OF THIS AREA, HEAT INDICES TO
AROUND 105 WILL BE MORE COMMON.
HOWEVER, THE SITUATION IS COMPLEX AS THE MODEL CONSENSUS FOR
THE GREATEST COVERAGE OF DIURNAL CONVECTION SHOULD COINCIDE WITH
THIS AREA OF HIGHEST POTENTIAL HEAT INDEX. THE PLAN WILL BE TO
GO WITH A HEAT ADVISORY FOR SOUTHEAST GA SOUTH OF I-16 AS WELL
AS BEAUFORT AND COASTAL JASPER COUNTIES. IF CONVECTION THEN
DEVELOPS EARLY ENOUGH TO DISRUPT PEAK HEATING AND PEAK HEAT
INDEX VALUES, THE ADVISORY COULD BE CANCELLED EARLY. CONCERNING
CONVECTION, THE MOST LIKELY SCENARIO IS FOR TYPICAL PULSE
SUMMERTIME THUNDERSTORMS THAT ARE MOSTLY SUB- SEVERE. MODEL
SOUNDINGS DO SHOW SOME POTENTIAL FOR ELEVATED DCAPE VALUES
(>1,000 J/KG) IS A VERY WEAKLY SHEARED ENVIRONMENT. A STRONG TO
MARGINALLY SEVERE STORM OR TWO IS POSSIBLE, ESPECIALLY WHERE
MORE SIGNIFICANT BOUNDARY COLLISIONS OCCUR.
KEY MESSAGE 2: HIGH TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL
ON TUESDAY, THEN GRADUALLY RISING THROUGH THE HOLIDAY WEEKEND.
HEAT ADVISORIES COULD BE NEEDED DURING THE HOLIDAY WEEKEND
ACROSS PORTIONS OF OUR AREA.
STRONG RIDGING WILL PERSIST OVER THE EASTERN HALF OF THE
COUNTRY ON TUESDAY, WITH A ROUGHLY 596 DAM 500 MB HIGH OVER THE
TN VALLEY. THIS IS AT LEAST 2 STANDARD DEVIATIONS ABOVE NORMAL
PER NAEFS. THIS HIGH WILL SHIFT TO OUR NORTH WEDNESDAY AND
THURSDAY, WHILE STRENGTHENING SLIGHTLY. THEN, IT'LL REMAIN IN
PLACE AND GRADUALLY WEAKEN LATE FRIDAY THROUGH THE HOLIDAY
WEEKEND.
THE COMBINATION OF RISING HEIGHTS AND INCREASING 850 MB
TEMPERATURES WILL CAUSE VERY HOT AND HUMID CONDITIONS TO SETTLE
OVER OUR REGION. HIGH TEMPERATURES WILL BE SLIGHTLY ABOVE NORMAL
ON TUESDAY, GENERALLY IN THE LOWER TO MIDDLE 90S. THEN, THEY'LL
INCREASE ABOUT 1-2 DEGREES EACH DAY THROUGH THE END OF THE
WEEK. IT APPEARS THE HOTTEST TEMPERATURES COULD BE ON THE 4TH OF
JULY OR SUNDAY, WHEN THEY PEAK IN THE UPPER 90S TO POSSIBLY 100
DEGREES ACROSS OUR AREA. EVEN THE BEACHES SHOULD BE IN THE 90S
BOTH OF THOSE DAYS. COMBINED WITH DEW POINTS IN THE 70S NEAR THE
COAST AND THE UPPER 60S FAR INLAND, AND WE COULD HAVE HEAT
INDICES WELL INTO THE 100S ACROSS OUR ENTIRE AREA FRIDAY INTO
THE HOLIDAY WEEKEND. HEAT INDICES COULD PEAK IN THE 105-110
DEGREE RANGE ON THE 4TH OF JULY AND SUNDAY, SO WE MAY NEED HEAT
ADVISORIES FOR PORTIONS OF OUR AREA.
AS FOR THE CONVECTIVE POTENTIAL, THE PATTERN WILL ONLY SUPPORT
SLIGHT CHANCE TO CHANCE POPS ALONG OUR GA COAST ON TUESDAY, THEN
DRY CONDITIONS WEDNESDAY AND THURSDAY, FOLLOWED BY POPS
GRADUALLY TRENDING HIGHER FRIDAY INTO THE HOLIDAY WEEKEND. EVEN
THOUGH POPS ARE NOT VERY HIGH, ANY CONVECTION THAT FORMS THIS
TIME OF YEAR, ESPECIALLY WITH THESE TEMPERATURES, WILL HAVE THE
POTENTIAL TO BE STRONG TO BORDERLINE SEVERE, ALONG WITH HAVING
LOCALLY HEAVY RAINFALL.
AVIATION /06Z MONDAY THROUGH FRIDAY/
THE 06Z TAF PERIOD BEGINS WITH VFR CONDITIONS AT KCHS, KJZI,
AND KSAV. HOWEVER, RADAR IMAGERY SHOWS BLOSSOMING SHOWER
COVERAGE ACROSS EASTERN BERKELEY AND UPPER CHARLESTON COUNTIES.
IT IS UNCLEAR IF THIS SHOWER ACTIVITY WILL REACH KCHS AND KJZI
OVER THE NEXT FEW HOURS. FOR NOW WE WILL LEAVE IT OUT OF THE
TAF'S AND HANDLE WITH AMENDMENTS IF NEEDED. ATTENTION THEN TURNS
TO THE POTENTIAL FOR AFTERNOON THUNDERSTORMS. MODEL CONSENSUS
IS FOR MOST SHOWER AND THUNDERSTORM ACTIVITY TO DEVELOP TO THE
SOUTHWEST OF KCHS AND KJZI, MEANING THAT KSAV WOULD HAVE THE
BEST CHANCE OF SEEING DIRECT IMPACTS. WE HAVE REMOVED THE PROB30
MENTION AT KCHS AND KJZI AND MAINTAINED IT AT KCHS.
EXTENDED AVIATION OUTLOOK: VFR.
MARINE
TODAY THROUGH TONIGHT: OVERALL, QUIET CONDITIONS EXPECTED
ACROSS THE LOCAL WATERS. NORTHWEST FLOW IS EXPECTED IN THE
MORNING, WEAKENING AND THEN TAKING ON THE SEA BREEZE CIRCULATION
IN THE AFTERNOON AND EVENING. WIND SPEEDS SHOULD MOSTLY TOP OUT
IN THE 10-15 KNOT RANGE. OVERNIGHT, STRENGTHENING NORTHEAST
FLOW SHOULD SPREAD IN WITH SPEEDS GETTING UP TO AROUND 15 KNOTS
BY SUNRISE TUESDAY. SEAS ARE EXPECTED TO AVERAGE 2-3 FEET.
EXTENDED MARINE: THE SYNOPTIC PATTERN WILL GENERALLY SUPPORT
WINDS FROM THE NE OR E THROUGH THURSDAY. THEN, THEY WILL CLOCK
AROUND TO THE SW BY FRIDAY MORNING. FRIDAY INTO THE HOLIDAY
WEEKEND, WINDS WILL HAVE A TYPICAL SUMMERTIME PATTERN. THIS WILL
CONSIST OF SOME BACKING DURING THE DAY, WITH THE HIGHEST WINDS
ALONG THE LAND/SEA INTERFACE WITH THE FORMATION OF THE SEA
BREEZE. GUSTS COULD APPROACH 20 KT, ESPECIALLY IN CHARLESTON
HARBOR AS THE SEA BREEZE MOVES THROUGH. AT NIGHT, EXPECT WINDS
TO VEER AND POSSIBLY EASE A FEW KT. SEAS SHOULD STAY 5 FT OR
LESS. NO SMALL CRAFT ADVISORIES ARE EXPECTED.
CLIMATE
RECORD HIGH TEMPERATURES:
JUNE 29:
KCHS: 99/1998
KSAV: 101/1959
JULY 4:
KCHS: 98/2023
KSAV: 99/1997
RECORD HIGH MINIMUM TEMPERATURES:
JULY 3:
KCHS: 78/2016
JULY 4:
KCHS: 79/2016
KSAV: 79/1931
CHS WATCHES/WARNINGS/ADVISORIES
GA...HEAT ADVISORY FROM NOON TODAY TO 6 PM EDT THIS EVENING FOR
GAZ114-115-137-216>219-238>241.
SC...HEAT ADVISORY FROM NOON TODAY TO 6 PM EDT THIS EVENING FOR
SCZ148-151.
MARINE...NONE.
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page