985
FXUS62 KCHS 281805
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
205 PM EDT MON JUL 28 2025
SYNOPSIS
ATLANTIC HIGH PRESSURE WILL PREVAIL EARLY THIS WEEK, WHILE A
TROUGH OF LOW PRESSURE RESIDES INLAND. A COLD FRONT COULD
APPROACH THE REGION LATE IN THE WEEK.
NEAR TERM /THROUGH TONIGHT/
REST OF THE AFTERNOON: A STRONG UPPER-LVL RIDGE SITUATED OVER
ARKLATEX REGION CONTINUES TO SHIFT WESTWARD, WHILE AN INLAND/LEE
TROUGH REMAINS IN PLACE. WEAK VORTICITY ASSOCIATED WITHIN
NORTHWESTERLY FLOW ALOFT IN THE AFOREMENTIONED UPPER-LVL RIDGE WILL
ALLOW FOR MID-LVL MOISTURE TO ADVECT INTO THE REGION. THEREFORE,
THIS WILL BE ENOUGH TO SPARK UP SHOWERS AND THUNDERSTORMS INLAND
AND/OR ALONG THE SEABREEZE THIS AFTERNOON. WHILE A WIDESPREAD SEVERE
WEATHER THREAT APPEARS UNLIKELY, FORECAST SOUNDINGS INDICATE MLCAPE
VALUES ~3000–4000 J/KG, WITH DCAPE VALUES ~1500 J/KG. THIS SETUP
COULD SUPPORT A FEW STRONG TO MARGINALLY SEVERE STORMS CAPABLE OF
PRODUCING DAMAGING WIND GUSTS. CONVECTION IS ALREADY POPPING UP OVER
THE INTERIOR COUNTIES OF SOUTH CAROLINA AND THE GREATEST COVERAGE
LOOK TO STAY NORTH OF I-16 AND AWAY FROM THE IMMEDIATE COAST WHERE
THE GREATER MOISTURE AND FORCING IS FOCUSED. ADDITIONALLY, WITH
PWATS IN EXCESS OF 2 INCHES AND SLOW-MOVING STORM MOTION (~5-10 KT),
ANY SHOWER AND/OR THUNDERSTORM THAT DOES DEVELOP COULD LEAD TO
LOCALIZED FLOODING. ACCORDING TO HREF QPF 3-HR PROBABILITIES, THE
AREA OF GREATEST CONCERN FOR LOCALIZED FLOODING WILL BE INLAND SOUTH
CAROLINA. LIGHT, WESTERLY SURFACE FLOW WILL RESULT IN A SEMI-PINNED
SEABREEZE AND PUSH MORE INLAND LATER THIS AFTERNOON, WHICH WILL
ADVECT UPPER 70S TO NEAR 80 DEW POINTS INLAND.
WITH TEMPERATURES INTO THE UPPER 90S TO LOW 100S, COMBINED WITH
DEWPOINTS IN THE MID 70S, HEAT INDICES WILL PEAK THIS AFTERNOON
AROUND 108 TO 115 TODAY. AS A RESULT, AN EXTREME HEAT WARNING IS IN
EFFECT FOR ALL COASTAL ZONES ACROSS SOUTHEAST SOUTH CAROLINA AND
SOUTHEAST GEORGIA INCLUDING BERKELEY, DORCHESTER, INLAND COLLETON,
INLAND JASPER, AND INLAND CHATHAM COUNTIES, AND A HEAT ADVISORY IS
IN EFFECT FOR THE REMAINING COUNTIES/ZONES. ALL THREE OF OUR LOCAL
CLIMATE SITES ARE FORECAST TO COME CLOSE TO BREAKING OR TYING RECORD
HIGHS AND/OR RECORD HIGH MINS TODAY/TONIGHT, SEE CLIMATE SECTION
BELOW FOR DETAILS.
AGAIN, ONE CAVEAT TO THE FORECAST IS THE PRESENCE OF THE STRONG
RIDGE ALOFT. MODEL CROSS SECTIONS SHOW NOTABLE SUBSIDENCE ALOFT,
WHICH COULD STUNT UPDRAFT STRENGTH AND POTENTIALLY LIMIT CONVECTIVE
INTENSITY. SO WITH THAT, IT WILL BE INTERESTING TO SEE HOW
CONVECTION EVOLVES THROUGHOUT THE AFTERNOON.
TONIGHT: ANY REMAINING CONVECTION SHOULD DISSIPATE LATER THIS
EVENING SETTING UP FOR RAIN-FREE NIGHT. CONDITIONS REMAIN WARM AND
MUGGY OVERNIGHT, WITH TEMPERATURES ONLY FALLING INTO THE MID TO
UPPER 70S INLAND AND STRUGGLING TO FALL BELOW 80 ALONG THE COASTAL
CORRIDOR.
SHORT TERM /TUESDAY THROUGH THURSDAY/
THE MID-LEVELS WILL CONSIST OF OUR REGION INITIALLY BEING ON THE
EASTERN PERIPHERY OF AN EXPANSIVE RIDGE. THOUGH, IT'LL BUILD BACK
OVER OUR AREA BY THURSDAY. AT THE SURFACE, HIGH PRESSURE WILL BE IN
THE ATLANTIC WITH TROUGHING INLAND.
EXPECT HOT AND HUMID CONDITIONS. TEMPERATURES WILL BE ABOVE NORMAL
WITH DEWPOINTS INTO THE MID TO UPPER 70S. THIS WILL EQUATE TO HEAT
INDICES REACHING HEAT ADVISORY CRITERIA OF 108-112F ON TUESDAY,
SLIGHTLY HIGHER IN SOME SPOTS. THEREFORE, WE HAVE A HEAT ADVISORY IN
EFFECT. THERE IS THE POTENTIAL FOR THIS HAPPENING AGAIN ON WEDNESDAY
AND THURSDAY. HOWEVER, CONVECTION COULD COOL TEMPERATURES BEFORE THE
HEAT PERSISTS TOO LONG BOTH OF THOSE DAYS.
THE MOST ACTIVE DAY OF THE SET APPEARS TO BE ON TUESDAY WITH BETTER
FORCING IN PLAY. NUMEROUS SHOWERS AND THUNDERSTORMS FORECAST TO
DEVELOP BY MID TO LATE AFTERNOON. POPS FOR WEDNESDAY AND THURSDAY
ARE MORE IN THE SCATTERED RANGE (30-50%). GIVEN THE AIRMASS IN
PLACE, A COUPLE STRONGER STORMS WITH DAMAGING WIND GUSTS WILL BE
POSSIBLE DESPITE RELATIVELY WEAK SHEAR, FOLLOWED BY LOCALLY HEAVY
RAINFALL.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
THERE WILL FINALLY BE REPRIEVE FROM THE OPPRESSIVE HEAT LATE WEEK
AND OVER THE WEEKEND AS MID LEVEL HEIGHTS FALL IN RESPONSE TO A
TROUGH OVER THE NORTHEAST AND MID-ATLANTIC. SOME TIMING
INCONSISTENCIES EXIST, BUT CONSENSUS SHOWS A COLD FRONT MOVING INTO
THE AREA AS HIGH PRESSURE BUILDS FROM THE NORTH. THIS WILL BRING
COOLER TEMPERATURES AND INCREASED RAIN CHANCES. THE FRONT COULD
STALL IN THE VICINITY THROUGH EARLY NEXT WEEK.
AVIATION /18Z MONDAY THROUGH SATURDAY/
28/18Z TAFS:
KCHS/KJZI/KSAV: AS THE UPPER-LVL RIDGE CONTINUES TO SHIFT
WESTWARD, ISOLATED TO SCATTERED THUNDERSTORMS MIGHT DEVELOP
~3-4PM INLAND AND/OR ALONG THE SEABREEZE. THE VCTS THAT WAS
MENTIONED IN THE 12Z TAF HAS BEEN KEPT AT KCHS AND KJZI AS THE
CONFIDENCE REMAINS LOW ON STORM COVERAGE. MOST CONVECTION LOOKS
TO STAY NORTH OF I-16, THUS LEFT THE MENTION OF VCTS OUT FOR
KSAV AT THIS TIME. IF A CONVECTION DOES DEVELOP AND PASS
DIRECTLY OVER A TERMINAL, REDUCTIONS IN VISIBILITY AND CEILINGS
ARE LIKELY.
EXTENDED AVIATION FORECAST: MAINLY VFR. EXPECT BRIEF FLIGHT
RESTRICTIONS IN AFTERNOON/EVENING SHOWERS/THUNDERSTORMS.
MARINE
REST OF AFTERNOON AND TONIGHT: EXPECT GENERALLY SOUTH-SOUTHWESTERLY
FLOW AT 5 TO 10 KT, WITH GUSTS UP TO 15 KT LATE THIS AFTERNOON. MIX
OF SOUTHEASTERLY SWELL WILL BE ON TAP FOR THE AFTERNOON. SEAS WILL
RANGE FROM 1 TO 2 FT OVERNIGHT. OTHERWISE, NO MARINE CONCERNS
EXPECTED.
EXTENDED MARINE: THE COASTAL WATERS WILL BE SANDWICHED BETWEEN HIGH
PRESSURE IN THE ATLANTIC AND COASTAL TROUGHING INLAND MOST OF THIS
WEEK. THIS WILL YIELD A TYPICAL SUMMERTIME WIND PATTERN.
EACH DAY, EXPECT BACKING WINDS WITH THE FORMATION OF THE AFTERNOON
SEA BREEZE. THE HIGHEST GUSTS WILL BE ALONG THE LAND/SEA INTERFACE
AND ACROSS CHARLESTON HARBOR (WITH ITS PASSAGE). EACH NIGHT, EXPECT
VEERING OF THE WINDS AS A NOCTURNAL JET SETS UP CLOSE TO SHORE. SEAS
WILL AVERAGE 1-3 FEET. A COLD FRONT IS EXPECTED TO MOVE INTO THE
REGION LATE THIS WEEK AND INTO THE WEEKEND. WINDS MAY TURN TO THE
NORTH AND EVENTUALLY NORTHEAST, AND INCREASE. BUT THESE DETAILS WILL
NEED TO BE IRONED OUT IN FUTURE FORECASTS.
CLIMATE
RECORD HIGH TEMPERATURES:
JULY 28:
KCHS: 101/1949
KCXM: 100/1936
KSAV: 102/1949
RECORD HIGH MINIMUM TEMPERATURES:
JULY 28:
KCHS: 80/2016
KCXM: 83/1999
KSAV: 81/1878
JULY 29:
KCHS: 80/2016
KSAV: 82/1878
JULY 30:
KCHS: 81/2016
KCXM: 83/2016
KSAV: 81/1878
JULY 31:
KCHS: 80/2022
KCXM: 84/2016
KSAV: 80/2010
AUGUST 1:
KCHS: 81/1999
KSAV: 79/2020
AUGUST 2:
KCHS: 79/2022
CHS WATCHES/WARNINGS/ADVISORIES
GA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR GAZ087-088-
099>101-114>116-137-138-140.
HEAT ADVISORY FROM 11 AM TO 8 PM EDT TUESDAY FOR GAZ087-088-
099>101-114>119-137>141.
EXTREME HEAT WARNING UNTIL 8 PM EDT THIS EVENING FOR
GAZ117>119-139-141.
SC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ040-042.
HEAT ADVISORY FROM 11 AM TO 8 PM EDT TUESDAY FOR SCZ040-
042>045-047>052.
EXTREME HEAT WARNING UNTIL 8 PM EDT THIS EVENING FOR
SCZ043>045-047>052.
MARINE...NONE.
NEAR TERM...DENNIS
SHORT TERM...
LONG TERM...
AVIATION...DENNIS
MARINE...DENNIS
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