933
FXUS62 KCHS 262256
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
656 PM EDT SAT JUL 26 2025
...EXTREME HEAT WARNING EXPANDED SOUTH TO INCLUDE MUCH OF THE
GEORGIA COAST AND THE SAVANNAH METRO AREA...
SYNOPSIS
ATLANTIC HIGH PRESSURE WILL PREVAIL THROUGH EARLY NEXT WEEK,
WHILE A TROUGH OF LOW PRESSURE RESIDES INLAND.
NEAR TERM /UNTIL 6 AM SUNDAY MORNING/
A PUBLIC INFORMATION STATEMENT HIGHLIGHTING MAXIMUM OBSERVED
HEAT INDICES SO FAR TODAY HAS BEEN ISSUED.
BASED ON INCOMING MODEL DATA AS WELL AS OBSERVED HEAT INDICES
BEHIND THE SEA BREEZE THIS AFTERNOON, THE DECISION HAS BEEN
MADE TO UPGRADE THE HEAT ADVISORY TO AN EXTREME HEAT WARNING
FOR INLAND COLLETON, INLAND JASPER, ALL OF CHATHAM COUNTY AS
WELL AS COASTAL PORTIONS OF LIBERTY, BRYAN AND MCINTOSH
COUNTIES. SEVERAL OBSERVATION SITES INCLUDING THOSE FROM THE
USGS AND THE UGA MESONET SHOW HEAT INDICES SURGED TO NEAR 113
FOR A FEW HOURS LATE THIS AFTERNOON AS DEWPOINTS SURGED INTO THE
UPPER 70S/LOWER 80S THE SEA BREEZE. SIMILAR BEHAVIOR IS LIKELY
TOMORROW WITH EVEN WARMER AFTERNOON HIGHS. THIS WILL LIKELY
PLACE MANY COASTAL AREAS ALONG THE GEORGIA COAST, INCLUDING MUCH
OF THE SAVANNAH METRO AREA, AND LOCATIONS ROUGHLY EAST OF I-95
IN SOUTH CAROLINA INTO EXCESSIVE HEAT WARNING LEVELS. THE
EXTREME HEAT WARNING WILL EXTEND INTO MONDAY.
CONDITIONS REMAIN WARM AND MUGGY OVERNIGHT, WITH TEMPERATURES
ONLY FALLING INTO THE MID TO UPPER 70S INLAND TO AROUND 80 NEAR
THE COAST AND BEACHES. THE HEAT ADVISORY WILL CONTINUE THROUGH
TONIGHT GIVEN THE LACK OF RELIEF FROM THE WARM OVERNIGHT
TEMPERATURES.
SHORT TERM /6 AM SUNDAY MORNING 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 SATURDAY/
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 /00Z SUNDAY THROUGH THURSDAY/
27/00Z TAF DISCUSSION:
KCHS/KJZI/KSAV: VFR THROUGH SUNDAY EVENING.
EXTENDED AVIATION FORECAST: PREVAILING VFR. BRIEF FLIGHT
RESTRICTIONS ARE POSSIBLE IN AFTERNOON SHOWERS/THUNDERSTORMS NEXT
WEEK.
MARINE
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
THE LOW TEMPERATURE OBSERVED SO FAR AT KCHS TODAY IS 79 DEGREES.
IF THIS HOLDS THROUGH 1 AM EDT SUNDAY, THIS WILL TIE THE RECORD
HIGH MINIMUM FOR THE DATE, LAST SET IN 2000.
RECORD HIGH TEMPERATURES:
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>116-137-138-140.
EXTREME HEAT WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING
FOR GAZ087-088-099>101-114>116-137-138-140.
HEAT ADVISORY UNTIL 10 AM EDT SUNDAY FOR GAZ117>119-139-141.
EXTREME HEAT WARNING FROM 10 AM SUNDAY TO 8 PM EDT MONDAY FOR
GAZ117>119-139-141.
SC...HEAT ADVISORY UNTIL 10 AM EDT MONDAY FOR SCZ040-042.
EXTREME HEAT WATCH FROM MONDAY MORNING THROUGH MONDAY EVENING
FOR SCZ040-042.
HEAT ADVISORY UNTIL 10 AM EDT SUNDAY FOR SCZ043>045-047>052.
EXTREME HEAT WARNING FROM 10 AM SUNDAY TO 8 PM EDT MONDAY FOR
SCZ043>045-047>052.
MARINE...NONE.
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