269  
FXUS62 KCHS 261835  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
235 PM EDT SAT JUL 26 2025  
   
SYNOPSIS  
 
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH EARLY NEXT WEEK,  
WHILE A TROUGH OF LOW PRESSURE RESIDES INLAND.  
 
 
   
NEAR TERM /THROUGH TONIGHT/  
 
REST OF THE AFTERNOON: STRONG UPPER-LEVEL RIDGING REMAINS  
CENTERED ACROSS THE SOUTHEAST, WITH 596 DAM NOTED ON 500MB  
ANALYSIS. AT THE SURFACE, HIGH PRESSURE RESIDES ACROSS THE  
FLORIDA/GEORGIA LINE, WITH AN INLAND TROUGH DEVELOPING  
THROUGHOUT THE DAY. AS THE 12Z CHS SOUNDING INDICATES, STRONG  
SUBSIDENCE AND MID-LEVEL DRY AIR WILL INHIBIT SHOWER AND  
THUNDERSTORM ACTIVITY THIS AFTERNOON. IN AGREEMENT WITH THIS,  
THE 15Z HRRR AND 12Z HREF HAVE KEPT POPS TO ZERO. THEREFORE, THE  
FORECAST HAS NO MENTIONABLE POPS FOR THIS AFTERNOON. SKIES WILL  
REMAIN MOSTLY SUNNY WITH SOME SHALLOW CUMULUS CLOUDS MAKING AN  
APPEARANCE. WITH TEMPERATURES INTO THE MID TO UPPER 90S,  
COMBINED WITH DEWPOINTS IN THE MID 70S, HEAT INDICES WILL PEAK  
THIS AFTERNOON AROUND 108 TO 112 TODAY. THUS, A HEAT ADVISORY  
REMAINS IN EFFECT FOR SOUTHEAST SOUTH CAROLINA AND GEORGIA FOR  
THE REST OF TODAY.  
 
TONIGHT: 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. THE  
HEAT ADVISORY WILL CONTINUE THROUGH TONIGHT GIVEN THE LACK OF  
RELIEF FROM THE WARM OVERNIGHT TEMPERATURES.  
 
 
   
SHORT TERM /SUNDAY THROUGH MONDAY/  
 
THE KEY CONCERN FOR SUNDAY AND MONDAY REMAINS THE HEAT. IF YOU HAVE  
TO GO OUTSIDE, PLEASE DRINK PLENTY OF FLUIDS AND STAY IN THE SHADE.  
IF AT ALL POSSIBLE, STAY IN AN AIR-CONDITIONED ROOM. CHECK UP ON  
RELATIVES AND NEIGHBORS.  
 
SUNDAY: THE MID-LEVEL RIDGE WILL CENTER ACROSS GEORGIA WITH HEIGHTS  
REACHING 597 DAM AND 1000/850 MB THICKNESSES AROUND 1440 M. THE GFS  
CONTINUES TO BE THE OUTLIER WITH LOW LEVEL THICKNESSES AT 1455 M  
NEAR KCAE. THE LATEST RUN OF THE ECMWF EXTREME FORECAST INDEX (EFI)  
SHOWS VALUES AROUND 0.8 INDICATING A STATISTICALLY SIGNIFICANT SHIFT  
FROM M-CLIMATE ON MAX TEMPERATURES WITH THE SHIFT OF TAIL (SOT)  
VALUES AROUND OR JUST SHY OF 1. THIS WOULD INDICATE SOME VALUES OF  
THE EPS EXCEEDING M-CLIMATE, BUT NOT ALL. PUTTING THIS INTO A  
STATISTICAL PERSPECTIVE, THE LAST TIME KCHS REACHED 100 F WAS MAY  
29, 2019 (JUNE 2022 FOR SAVANNAH). ALSO TAKING A LOOK AT THE BC NBM,  
THERE IS A SLIGHT NUDGE UPWARD (1 OR 2 DEGREES) COMPARED TO THE RAW  
GUIDANCE. GIVEN THE THICKNESSES, EFI, SOT, AND BC NBM VALUES THIS  
WOULD SUPPORT HIGH TEMPERATURES RIGHT AT OR NEAR 100 F. THERE WILL  
BE SOME MIXING OF DEWPOINTS ON SUNDAY, BUT OVERALL NOT MUCH AT ALL  
IN THE WAY OF RELIEF. FOR THE TRICOUNTY, EXPECT WIDESPREAD HEAT  
INDEX VALES OF 110 F TO 115 F. GIVEN THIS, WE HAVE OPTED TO ISSUE AN  
EXTREME HEAT WARNING FOR THE TRICOUNTY AND COASTAL SOUTH CAROLINA.  
MONDAY NIGHT, LOW TEMPERATURES WILL ONLY FALL TO AROUND 80 F  
OFFERING LITTLE IN THE WAY OF RELIEF.  
 
MONDAY: THE MID-LEVEL CENTER WILL NUDGE WEST WITH HEIGHTS STARTING  
TO SLOWLY FALL. LOW LEVEL THICKNESSES WILL ALSO SLOWLY START TO  
FALL/ RESPOND. HIGH TEMPERATURES MONDAY WILL BE SIMILAR TO SUNDAY,  
BUT PROBABLY A DEGREE COOLER. HOWEVER, DEWPOINTS WILL LIKELY NOT MIX  
OUT AS MUCH. AS SUCH, THE EXTREME HEAT WARNING FOR THE TRICOUNTY AND  
COASTAL SC HAS BEEN CONTINUED THROUGH MONDAY EVENING. AN EXTREME  
HEAT WATCH REMAINS FOR THE OTHER ZONES ON MONDAY.  
 
 
   
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/  
 
LATEST WPC CLUSTER ANALYSIS SHOWS GLOBAL ENSEMBLES IN GOOD AGREEMENT  
WITH MID-LEVEL RIDGING BEGINNING TO SPLIT WEDNESDAY/ THURSDAY. THIS  
IS DUE TO VORTICITY ON TUESDAY THAT IS FORECAST TO UNDERCUT THE  
RIDGE AND THEN MOVE WEST. AS THIS OCCURS, THE RIDGE WILL BEGIN TO  
BREAK DOWN OVER THE SOUTHERN MISSISSIPPI RIVER VALLEY WITH HEIGHTS  
RISING OVER THE SOUTHWESTERN PLAINS WITH HEIGHTS FALLING OVER THE  
EASTERN UNITED STATES. THE RIDGING ACROSS THE SOUTHEASTERN UNITED  
STATES THEN BEGINS TO REFORM OVER FLORIDA. THIS TYPE OF PATTERN  
FAVORS TEMPERATURES ABOVE NORMAL, BUT NOT NEAR AS WARM AS THIS  
WEEKEND (HIGHS IN THE LOW TO MID 90S). A CHANCE OF SHOWERS AND  
THUNDERSTORMS WILL ALSO EXIST EVERY AFTERNOON THANKS TO PLENTIFUL  
INSTABILITY AND THE LACK OF RIDGING OVERHEAD.  
 
ONE THING OF NOTE IS THE VORTICITY THAT IS SCHEDULED TO ROUND THE  
NORTHEAST FLANK OF THE MID-LEVEL RIDGE LATE MONDAY/ EARLY TUESDAY.  
GLOBAL GUIDANCE SHOWS A STRONG CONVECTIVE SIGNAL WITH A WEDGE OF PVA  
SWEEPING SOUTH OUT OF NC MONDAY EVENING AND THEN MOVES IT OVERHEAD  
TUESDAY MORNING. MID AND UPPER LEVEL RH OUT AHEAD OF THE WAVE IS  
ONLY AROUND 20%, WHICH WILL HELP BOOST DCAPE VALUES WELL ABOVE 1000  
J/KG. THE PROBABILITY OF CONVECTION REMAINS RELATIVELY LOW, BUT IF  
CONVECTION WERE TO FORM DAMAGING WIND GUSTS WOULD BE POSSIBLE.  
 
 
   
AVIATION /18Z SATURDAY THROUGH THURSDAY/  
 
18Z TAFS: WITH THE UPPER-LEVEL RIDGING OVERHEAD AND MID-LEVEL  
SUBSIDENCE, VFR SHOULD REMAIN THROUGHOUT THE PERIOD.  
 
EXTENDED AVIATION FORECAST: PREVAILING VFR. BRIEF FLIGHT  
RESTRICTIONS ARE POSSIBLE IN AFTERNOON SHOWERS/THUNDERSTORMS NEXT  
WEEK.  
 
 
   
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 SOUTHERLY WINDSWELL AND UNDERLYING  
EASTERLY-SOUTHEASTERLY SWELL WILL BE ON TAP FOR THE AFTERNOON.  
SEAS WILL RANGE FROM 2 TO 3 FT OVERNIGHT. OTHERWISE, NO MARINE  
CONCERNS EXPECTED.  
 
SUNDAY THROUGH THURSDAY: NO MARINE CONCERNS ARE ANTICIPATED THROUGH  
THE WEEK. SOUTHERLY FLOW IS EXPECTED, WITH A SLIGHT BACKING OF THE  
WINDS EACH AFTERNOON FOR THE SEA BREEZE WITH ATLANTIC HIGH PRESSURE  
TO THE SOUTHEAST OF BERMUDA. WIND SPEEDS WILL GENERALLY BE LESS THAN  
15 KNOTS WITH SEAS 1 TO 3 FEET.  
 
 
   
CLIMATE  
 
RECORD HIGH TEMPERATURES:  
 
JULY 26: KCHS: 99/2010  
 
JULY 27: KCHS: 100/2005 KSAV: 100/2010  
 
JULY 28: KSAV: 102/1949  
 
RECORD HIGH MINIMUM TEMPERATURES:  
 
JULY 26: KCHS: 78/2012 KSAV: 80/1884  
 
JULY 27: KCHS: 80/2014 KSAV: 80/1885  
 
JULY 28: KCHS: 80/2016 KCXM: 83/1999 KSAV: 81/1878  
 
JULY 29: KCHS: 80/2016  
 
JULY 30: KCHS: 81/2016 KSAV: 81/1878  
 
JULY 31: KCHS: 80/2022 KSAV: 80/2010  
 
AUGUST 1: KSAV: 79/2020  
 
 
   
CHS WATCHES/WARNINGS/ADVISORIES  
 
GA...HEAT ADVISORY UNTIL 10 AM EDT MONDAY FOR GAZ087-088-099>101-  
114>119-137>141.  
EXTREME HEAT WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING  
FOR GAZ087-088-099>101-114>119-137>141.  
SC...HEAT ADVISORY UNTIL 10 AM EDT MONDAY FOR SCZ040-042-043-047.  
EXTREME HEAT WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING  
FOR SCZ040-042-043-047.  
HEAT ADVISORY UNTIL 10 AM EDT SUNDAY FOR SCZ044-045-048>052.  
EXTREME HEAT WARNING FROM 10 AM SUNDAY TO 8 PM EDT MONDAY FOR  
SCZ044-045-048>052.  
MARINE...NONE.  
 
 
 
 
 
NEAR TERM...DENNIS  
SHORT TERM...HAINES  
LONG TERM...HAINES  
AVIATION...DENNIS/HAINES  
MARINE...DENNIS/HAINES  
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