243
FXUS62 KCHS 290625
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
225 AM EDT TUE JUL 29 2025
SYNOPSIS
ATLANTIC HIGH PRESSURE WILL PREVAIL FOR MOST OF THE WEEK,
RESULTING IN HOT AND HUMID CONDITIONS ACROSS THE REGION. A COLD
FRONT THEN LOOKS TO DIVE ACROSS OUR AREA FRIDAY, ALLOWING
COOLER TEMPERATURES AND INCREASED RAIN CHANCES TO RETURN OVER
THE WEEKEND.
NEAR TERM /UNTIL 6 AM THIS MORNING/
TODAY: A STRONG AND EXPANSIVE UPPER LEVEL RIDGE (H5 598 DAM)
WILL REMAIN IN PLACE OVER THE CENTRAL AND SOUTHEAST U.S., WHILE
A WEAK AND SOMEWHAT BROAD AREA OF LOW PRESSURE RESIDES OVER THE
FORECAST AREA. EMBEDDED WEAK VORTICITY IN THE NORTHWESTERLY
UPPER-LEVEL FLOW WILL CONTINUE ROTATING AROUND THE NORTHEASTERN
EDGE OF THE RIDGE, ADVECTING UPPER-LEVEL FORCING INTO THE
REGION. WITH DEEP MOISTURE IN PLACE (PWATS AROUND 2.25"),
NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP IN
THE AFTERNOON AND CONTINUE THROUGH THE EVENING. LIGHT SURFACE
WINDS WILL FAVOR AN INLAND MOVING SEA BREEZE, WHICH IS WHERE
INITIAL CONVECTION IS MOST LIKELY TO DEVELOP, KEEPING MOST OF
THE STORM ACTIVITY AWAY FROM THE IMMEDIATE COASTLINE. THERE
COULD EVEN BE AN ISOLATED SHOWER OR THUNDERSTORM SPARK EARLY
THIS MORNING WITH SOME INSTABILITY AND UPPER FORCING MECHANISMS
AT PLAY. STRONG DAYTIME HEATING WILL DRIVE MLCAPE VALUES UP TO
4000–5000 J/KG, WITH DCAPE VALUES RANGING FROM 700–900 J/KG.
THIS ENVIRONMENT SUPPORTS THE POTENTIAL FOR A FEW STRONG STORMS
CAPABLE OF PRODUCING DAMAGING WIND GUSTS. STORM MOTION WILL ONCE
AGAIN BE SLOW, AROUND 5–10 KT, RAISING THE RISK OF LOCALIZED
FLOODING DURING HEAVIER DOWNPOURS. SOME AREAS COULD SEE 1 TO 2
INCHES OF RAIN FALL QUICKLY. HREF GUIDANCE INDICATES A 30–60%
CHANCE OF AREAS RECEIVING 2+ INCHES OF RAIN, MAINLY FOR AREAS
ALONG THE SEA BREEZE BOUNDARY, WITH A 10–30% CHANCE OF AMOUNTS 3
INCHES OR GREATER.
TEMPERATURES WILL BE SLIGHTLY COOLER THAN PREVIOUS DAYS BUT STILL
UNCOMFORTABLE, WITH HIGHS REACHING THE MID TO UPPER 90S INLAND AND
AROUND 90 DEGREES ALONG THE COAST. FORECASTING HEAT INDICES WILL
BE CHALLENGING TODAY DUE TO THE COOLING EFFECTS OF STORMS, BUT
MOST AREAS ARE EXPECTED TO PEAK AROUND 108-111 BEFORE CONVECTION
DEVELOPS. A HEAT ADVISORY IS IN EFFECT FOR ALL COUNTIES IN
SOUTHEAST SOUTH CAROLINA AND SOUTHEAST GEORGIA.
TONIGHT: SHOWER AND THUNDERSTORM ACTIVITY WILL GRADUALLY TAPER OFF
LATE IN THE EVENING AS INSTABILITY DIMINISHES, LEADING TO MOSTLY DRY
CONDITIONS BY MIDNIGHT. HOWEVER, SOME MODEL GUIDANCE SUGGESTS
INCREASING VORTICITY ALOFT OVERNIGHT, WHICH COMBINED WITH DEEP
MOISTURE AND WARM TEMPERATURES COULD SPARK ISOLATED SHOWERS OR
THUNDERSTORMS OVERNIGHT. LOWS WILL REMAIN MILD, RANGING FROM THE MID
TO UPPER 70S INLAND TO AROUND 80 DEGREES NEAR THE COAST.
SHORT TERM /6 AM THIS MORNING THROUGH THURSDAY/
HOT AND HUMID CONDITIONS CONTINUE MID-WEEK AS UPPER LEVEL RIDGE
MAINTAINS ITS INFLUENCE OVER THE REGION. SIMILAR TO DAYS PAST, HAVE
AFTERNOON HIGHS RISING INTO THE 90S WITH DEWPOINTS IN THE MID TO
UPPER 70S. AS A RESULT, EXPECT HEAT INDICES TO RANGE FROM 102
ACROSS OUR INTERIOR COUNTIES, TO 110-112 DEGREES ACROSS OUR COASTAL
COUNTIES. WHILE AN ADVISORY WILL LIKELY BE NEEDED ACROSS PORTIONS OF
OUR AREA WEDNESDAY, HAVE OPTED TO FORGO ANY HEADLINES WITH THIS
FORECAST PACKAGE AFTER COLLABORATION WITH NEIGHBORS. IN TERMS OF
PRECIPITATION, LATEST CAMS SHOW SCATTERED SHOWERS AND STORMS
DEVELOPING DURING THE AFTERNOON AND EARLY EVENING. 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.
LOOK FOR A RINSE AND REPEAT ON THURSDAY AS THE RIDGE AXIS REMAINS
NEARBY. SFC COLD FRONT THEN LOOKS TO DIVE ACROSS THE SOUTHEASTERN
CONUS LATE THURSDAY NIGHT INTO FRIDAY, ALLOWING THE STAGNANT UPPER
LEVEL PATTERN TO FINALLY SHIFT. THAT BEING SAID, STILL HAVE A FEW
TIMING DIFFERENCES TO IRON OUT WITH THE FRONT, AS THIS WILL
ULTIMATELY AFFECT WHEN WE FINALLY SEE COOLER TEMPERATURES. FOR NOW,
MOST GUIDANCE HINTS THAT AFTERNOON HIGHS IN THE 90S WILL CONTINUE AT
LEAST THROUGH FRIDAY, IN ADDITION TO DIURNALLY DRIVEN SHOWERS AND
STORMS.
LONG TERM /THURSDAY NIGHT THROUGH MONDAY/
A REPRIEVE FROM THE HEAT FINALLY ARRIVES OVER THE WEEKEND, AS A SFC
COLD FRONT CONTINUES TO SAGE SOUTHEASTWARD ACROSS OUR AREA. AS SUCH,
LOOK FOR HIGHS IN THE MID 80S TO LOWER 90S TO PREVAIL SATURDAY, WITH
HIGHS IN THE LOW TO MID 80S BECOMING COMMON SUNDAY INTO MONDAY.
WHILE SOME TIMING FLUCTUATIONS WITH THE FRONT ARE STILL POSSIBLE,
LATEST GUIDANCE CONTINUES TO SUGGEST THE BETTER CHANCES FOR SEEING
MEANINGFUL RAINFALL WILL OCCUR LATE FRIDAY NIGHT INTO SATURDAY, AND
ESPECIALLY SATURDAY AFTERNOON. OTHERWISE, WILL LIKELY SEE THE FRONT
STALL ALONG THE COAST HEADING INTO THE NEW WEEK.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
06Z TUESDAY: MAINLY VFR THROUGH EARLY TUESDAY AFTERNOON. THEN FLIGHT
RESTRICTIONS ARE LIKELY TUESDAY AFTERNOON AS NUMEROUS SHOWERS
AND THUNDERSTORMS DEVELOP ACROSS THE AREA. THE GREATER CHANCES
APPEAR TO OCCUR AWAY FROM THE IMMEDIATE COAST, AND CLOSER TO
KCHS/KSAV TERMINALS MID AFTERNOON INTO THE EVENING. THERE IS
POTENTIAL FOR DIRECT IMPACTS AT THOSE TERMINALS, HOWEVER MORE
DETAILS WILL LIKELY COME WITH THE 12Z TAF ISSUANCE. FOR NOW WE
MAINTAINED VCTS FOR KCHS AND KSAV FROM 19-23Z TUESDAY.
EXTENDED AVIATION FORECAST: MAINLY VFR. EXPECT BRIEF FLIGHT
RESTRICTIONS IN AFTERNOON/EVENING SHOWERS/THUNDERSTORMS.
MARINE
TODAY AND TONIGHT: NO MARINE CONCERNS WITH LIGHT SOUTHERLY WINDS
AROUND 5-10 KT THROUGH TUESDAY NIGHT. SEAS WILL RANGE 1-2 FEET.
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 MINIMUM TEMPERATURES:
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 FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING
FOR GAZ087-088-099>101-114>119-137>141.
SC...HEAT ADVISORY FROM 11 AM THIS MORNING TO 8 PM EDT THIS EVENING
FOR SCZ040-042>045-047>052.
MARINE...NONE.
NEAR TERM...BRS
SHORT TERM...SST
LONG TERM...SST
AVIATION...BRS/SST
MARINE...BRS/SST
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