568  
FXUS62 KCHS 251820  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
220 PM EDT FRI JUL 25 2025  
   
SYNOPSIS
 
 
ATLANTIC HIGH PRESSURE WILL PREVAIL INTO EARLY NEXT WEEK, WHILE  
A TROUGH OF LOW PRESSURE RESIDES INLAND.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
WATER VAPOR IMAGERY SHOWS THE CENTER OF A RIDGE OF HIGH PRESSURE OFF  
THE NC/SC COAST, WITH MODELS INDICATING THE STRENGTH AT 500 MB NEAR  
595 DM. AT THE SURFACE, A HIGH PRESSURE IS EAST OF THE GA/FL COAST  
AND A BROAD LOW PRESSURE OVER THE DEEP SOUTH. THIS HAS RESULTED IN  
WEAK SOUTH-SOUTHWESTERLY FLOW WITH TEMPERATURES IN THE UPPER 80S TO  
LOWER 90S, RISING INTO LOWER TO MID 90S AREA-WIDE BEFORE DECREASING  
INTO THE EVENING HOURS. WITH DEWPOINTS IN THE MID/UPPER 70S, HEAT  
INDEX VALUES OF 104-107 ARE EXPECTED THIS AFTERNOON. HOWEVER,  
PORTIONS OF THE SOUTH CAROLINA LOWCOUNTRY WILL LIKELY SEE HEAT INDEX  
VALUES OF 108+ FOR A FEW HOURS THIS AFTERNOON, SO HAVE ISSUED A HEAT  
ADVISORY FOR TODAY AND WILL CARRY IT OVERNIGHT INTO TOMORROW GIVEN  
THIS IS THE START OF THE PROLONGED HEAT WAVE FOR THE REGION.  
 
AS FOR CHANCES FOR RAIN, WE'VE OBSERVED A FEW SHOWERS ATTEMPTING TO  
FORM, BUT WITH THE STRONG DOWNWARD VERTICAL MOTION FROM THE RIDGE  
STORMS HAVE NOT BEEN ABLE TO SUSTAIN THEMSELVES. IN THE NORTHWEST  
QUADRANT OF THE SURFACE HIGH ACROSS SOUTHEASTERN GA, WEAK POSITIVE  
THETA-E ADVECTION IN COMBINATION WITH THE SEA-BREEZE WILL ATTEMPT TO  
CREATE ADDITIONAL SHOWERS/TSTORMS, AS EVIDENT BY THE AGITATED CU  
FIELD ALONG THE SEA-BREEZE IN SOUTHEASTERN GA. FOR TONIGHT, EXPECT  
THE WARM CONDITIONS TO CONTINUE WITH OVERNIGHT LOWS ONLY DIPPING  
DOWN INTO THE LOWER TO UPPER 70S, WARMEST ALONG THE COAST. MAY BE  
ABLE TO BREAK RECORD HIGH MINIMUM TEMPERATURES, BUT CURRENT FORECAST  
HAS US STAYING 2 DEGREES ON THE COOL SIDE.  
 

 
   
SHORT TERM /SATURDAY THROUGH MONDAY/
 
 
MAIN FOCUS FOR THE PERIOD WILL BE THE LONG-DURATION HEAT SET TO  
IMPACT THE REGION. HEAT ADVISORIES AND/OR EXTREME HEAT  
WATCHES/WARNINGS WILL LIKELY BE NEEDED.  
 
A STRONG MID LEVEL RIDGE, NOTED BY 500 MB HEIGHTS 2-3 STANDARD  
DEVIATIONS ABOVE NORMAL PER NAEFS, WILL BECOME SITUATED OVERHEAD FOR  
THE WEEKEND AND EARLY NEXT WEEK. AT THE SURFACE, TROUGH WILL RESIDE  
INLAND, WHILE HIGH PRESSURE REMAINS OFFSHORE WITH A WEAK GRADIENT  
LOCALLY. THIS PATTERN SUPPORTS VERY HOT TEMPERATURES AND LIMITED  
PRECIPITATION, ESPECIALLY WHEN COINCIDING WITH THE  
CLIMATOLOGICALLY-HOTTEST TIME OF YEAR.  
 
TEMPERATURES...NEAR RECORD HIGH TEMPERATURES ARE FORECAST THROUGH  
EARLY NEXT WEEK (SEE CLIMATE SECTION BELOW). TEMPERATURES WILL BE  
HOTTEST SUNDAY AND MONDAY WHEN HIGHS COULD EXCEED 100F IN SEVERAL  
LOCATIONS AWAY FROM THE IMMEDIATE COAST. HEAT INDICES WILL BE EVEN  
HIGHER, LIKELY REACHING HEAT ADVISORY CRITERIA (108F) AND EVEN  
APPROACHING OR EXCEEDING EXTREME HEAT WARNING CRITERIA (113F) IN  
MANY SPOTS. LITTLE RELIEF IS EXPECTED OVERNIGHT WITH LOWS ONLY IN  
THE UPPER 70S TO AROUND 80, WHICH WOULD STILL BRING HEAT INDEX  
VALUES IN THE UPPER 80S TO 90S ALONG THE COAST OVERNIGHT. THIS KIND  
OF RELENTLESS HEAT IS DANGEROUS TO VULNERABLE POPULATIONS EVEN  
OVERNIGHT.  
 
CONVECTION-WISE...THE WEEKEND SHOULD BE FAIRLY QUIET WITH JUST  
ISOLATED SHOWERS/THUNDERSTORMS POSSIBLE ON SUNDAY, MAINLY FROM  
COLLETON COUNTY NORTHWARD. THE RIDGE WILL EXPAND AND SHIFT SLIGHTLY  
WESTWARD ON MONDAY. THIS COULD BRING A SLIGHTLY HIGHER CHANCE FOR  
SHOWERS/THUNDERSTORMS WITH SOME SIGNALS OF A WEAK SHORTWAVE DROPPING  
THROUGH THE AREA ON PERIPHERY OF THE RIDGE LATE IN THE DAY. POPS ARE  
GENERALLY IN THE 20-30% RANGE.  
 

 
   
LONG TERM /MONDAY NIGHT THROUGH FRIDAY/
 
 
THE FORECAST AREA WILL REMAIN UNDER THE INFLUENCE OF AN EXPANSIVE  
UPPER RIDGE CENTERED OVER THE SOUTH CENTRAL U.S. THROUGH THE MIDDLE  
OF NEXT WEEK. CONSENSUS SHOWS A LARGER SCALE TROUGH MOVING INTO THE  
NORTHEASTERN U.S. LATE. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE  
POSSIBLE EACH DAY, PRIMARILY DURING THE AFTERNOON WHEN INSTABILITY  
IS MAXIMIZED. MAIN FORECAST CONCERN REMAINS THE PROLONGED HEAT. HEAT  
INDICES HAVE THE POTENTIAL TO REACH HEAT ADVISORY AND/OR EXTREME  
HEAT WATCH/WARNING CRITERIA THROUGH AT LEAST WEDNESDAY, PERHAPS  
EXTENDING INTO THURSDAY AS WELL, THOUGH INCREASED CLOUD COVER AND  
SHOWER/STORM UNCERTAINTY MAKE THIS PORTION OF THE FORECAST LESS  
CERTAIN.  
 

 
   
AVIATION /19Z FRIDAY THROUGH WEDNESDAY/
 
 
LARGELY VFR CONDITIONS EXPECTED ACROSS THE REGION THROUGHOUT  
THE PERIOD, THOUGH CAN'T RULE OUT VERY MARGINAL MVFR CIGS AT  
FL029 AT JZI FOR A FEW MORE HOURS THIS AFTERNOON. WINDS WILL  
REMAIN LIGHT, THOUGH VARIABLE AT TIMES AS THEY SWITCH FROM  
SOUTHWEST-SOUTHEASTERLY TO EASTERLY BY TOMORROW MORNING.  
 
EXTENDED AVIATION FORECAST: PREVAILING VFR. BRIEF FLIGHT  
RESTRICTIONS ARE POSSIBLE IN AFTERNOON SHOWERS/THUNDERSTORMS NEXT  
WEEK.  
 

 
   
MARINE
 
 
THE SFC PATTERN WILL SUPPORT STEADY SOUTH WINDS AROUND 10 KTS ACROSS  
THE MARINE ZONES TODAY, SHIFTING FROM THE SOUTHWEST TONIGHT TO THE  
WEST BY SATURDAY MORNING. WAVE HEIGHTS SHOULD GENERALLY RANGE  
BETWEEN 2 TO 3 FT.  
 
SATURDAY THROUGH WEDNESDAY: NO MARINE CONCERNS ARE ANTICIPATED OVER  
THE WEEKEND AND INTO THE MIDDLE OF NEXT WEEK. GENERALLY EXPECT  
SOUTHERLY FLOW WITH SPEEDS LESS THAN 15 KNOTS. SEAS WILL AVERAGE 1-3  
FEET.  
 

 
   
CLIMATE
 
 
RECORD HIGH TEMPERATURES:  
 
JULY 26:  
KCHS: 99/2010  
 
JULY 27:  
KCHS: 100/2005  
KSAV: 100/2010  
 
JULY 28:  
KCHS: 101/1949  
KSAV: 102/1949  
 
RECORD HIGH MINIMUM TEMPERATURES:  
 
JULY 26:  
KCHS: 78/2012  
 
JULY 27:  
KCHS: 80/2014  
KCXM: 84/2021  
KSAV: 80/1885  
 
JULY 28:  
KCHS: 80/2016  
KCXM: 83/1999  
KSAV: 81/1878  
 
JULY 29:  
KCHS: 80/2016  
 
JULY 30:  
KCHS: 81/2016  
KCXM: 83/2016  
KSAV: 81/1878  
 
JULY 31:  
KCHS: 80/2022  
KSAV: 80/2010  
 

 
   
CHS WATCHES/WARNINGS/ADVISORIES
 
 
GA...HEAT ADVISORY FROM 10 AM SATURDAY TO 10 AM EDT SUNDAY FOR  
GAZ087-088-099>101-114>119-137>141.  
EXTREME HEAT WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING  
FOR GAZ087-088-099>101-114>119-137>141.  
SC...HEAT ADVISORY FROM 10 AM SATURDAY TO 10 AM EDT SUNDAY FOR  
SCZ040-042.  
EXTREME HEAT WATCH FROM SUNDAY MORNING THROUGH MONDAY EVENING  
FOR SCZ040-042>045-047>052.  
HEAT ADVISORY UNTIL 10 AM EDT SUNDAY FOR SCZ043>045-047>052.  
MARINE...NONE.  
 

 
 

 
 
NEAR TERM...APT  
SHORT TERM...CEB  
LONG TERM...CEB  
AVIATION...APT/CEB  
MARINE...APT/CEB  
 
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