279  
FNUS72 KCHS 200858  
FWSCHS  
 
SPOT FORECAST FOR HORSE ISLAND WILDFIRE...USFS  
NATIONAL WEATHER SERVICE CHARLESTON SC  
458 AM EDT MON JUL 20 2026  
 
FORECAST IS BASED ON FORECAST START TIME OF 0900 EDT ON JULY 20.  
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER  
SERVICE.  
   
DISCUSSION  
 
MOSTLY DRY AND HOT CONDITIONS WILL PERSIST THROUGH TODAY,  
ALTHOUGH THERE IS A RISK FOR AN ISOLATED SHOWER OR THUNDERSTORM  
DURING THE LATE AFTERNOON HOURS ROUGHLY BETWEEN 1 PM AND 4 PM.  
RELATIVE HUMIDITY VALUES WILL BE GENERALLY AROUND 45 TO 50 PERCENT  
THIS AFTERNOON. THE BIGGEST CONCERNS WILL BE THE SEABREEZE THIS  
AFTERNOON WHICH WILL LIKELY REACH THE BURN SITE AROUND 3 TO 4 PM.  
WIND GUSTS TO AROUND 15 TO 20 MPH WILL BE POSSIBLE BEHIND THE  
SEABREEZE MOSTLY OUT OF THE SOUTH; HOWEVER, STRONGER GUSTS COULD  
BE MORE VARIABLE. TRANSPORT WINDS WILL BE PREDOMINANTLY  
SOUTHWESTERLY BECOMING MORE SOUTHERLY BY THE LATE AFTERNOON. WINDS  
SHOULD QUICKLY RELAX AROUND SUNSET AS MORE STABLE CONIDITONS  
SETTLE IN OVERNIGHT WITH CONTINUED DENSE SMOKE ISSUES POSSIBLE.  
 
   
REST OF TODAY  
 
SKY/WEATHER.........MOSTLY SUNNY. SMOKE.  
CHANCE OF PCPN......10 PERCENT.  
MAX TEMPERATURE.....AROUND 95.  
MIN HUMIDITY........54 PERCENT.  
WIND (20 FT)........LIGHT WINDS BECOMING SOUTH 5 TO 7 MPH WITH  
GUSTS TO AROUND 16 MPH IN THE AFTERNOON.  
MIXING HEIGHT.......MAX 4900 FT AGL.  
TRANSPORT WINDS.....SOUTHWEST 12 TO 14 MPH.  
MAX ADI.............69.  
INVERSION END.......0900  
 
TIME (EDT) 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM  
SKY (%).........28 44 56 59 56 59 50 48 42  
WEATHER TYPE....SMK SMK SMK SMK SMK SMK SMK SMK SMK  
TSTM COV........  
CHC OF PCPN (%).0 0 0 10 10 10 10 10 10  
TEMP............84 88 90 91 93 93 93 94 92  
RH..............85 72 68 60 56 56 56 54 58  
20 FT WIND DIR..SW SW SW SW S S S S S  
20 FT WIND SPD..3 3 4 4 5 5 6 7 7  
20 FT WIND GUST.11 11 11 11 13 13 14 16 16  
MIX HGT (KFT)...2.7 3.5 4.0 4.6 4.9 4.5 4.4 4.1 3.8  
TRANSP WIND DIR.SW SW SW SW SW SW SW SW SW  
TRANSP WIND SPD.12 12 12 12 12 12 14 14 14  
LVORI...........4 3 3 1 1 1 1 1 1  
ADI.............40 52 39 41 47 45 66 67 69  
   
TONIGHT  
 
SKY/WEATHER.........PARTLY CLOUDY THEN BECOMING MOSTLY CLOUDY THEN  
BECOMING PARTLY CLOUDY.  
CHANCE OF PCPN......10 PERCENT.  
MIN TEMPERATURE.....AROUND 78.  
MAX HUMIDITY........94 PERCENT.  
WIND (20 FT)........SOUTH WINDS 5 TO 7 MPH WITH GUSTS TO AROUND 16  
MPH EARLY IN THE EVENING BECOMING LIGHT.  
MAX LVORI...........7.  
MIN ADI.............1.  
INVERSION BEGIN.....2000  
 
TIME (EDT) 6 PM 8 PM 10 PM MIDNGT 2 AM 4 AM  
SKY (%).........45 52 35 25 27 19  
WEATHER TYPE....NONE NONE NONE NONE NONE NONE  
TSTM COV........  
CHC OF PCPN (%).10 0 0 0 0 10  
TEMP............90 86 82 82 81 80  
RH..............62 72 85 85 85 91  
20 FT WIND......S 7 S 5 S 4 S 3 S 3 S 3  
20 FT WIND GUST.16 14 14 13 13 13  
MIX HGT (FT)....3300 800 500 500 500 500  
TRANSPORT WIND..S 12 S 12 S 4 S 4 S 4 S 4  
LVORI...........3 3 5 5 5 7  
ADI.............1 4 2 2 2 2  
   
TUESDAY  
 
SKY/WEATHER.........SUNNY.  
CHANCE OF PCPN......10 PERCENT.  
MAX TEMPERATURE.....AROUND 95.  
MIN HUMIDITY........51 PERCENT.  
WIND (20 FT)........LIGHT WINDS BECOMING SOUTH 5 TO 11 MPH WITH  
GUSTS TO AROUND 22 MPH IN THE LATE MORNING AND  
AFTERNOON.  
MIXING HEIGHT.......MAX 5700 FT AGL.  
TRANSPORT WINDS.....LIGHT WINDS BECOMING SOUTHWEST 16 TO 22 MPH IN  
THE LATE MORNING AND AFTERNOON.  
MAX ADI.............111.  
INVERSION END.......0900  
 
TIME (EDT) 6 AM 9 AM NOON 3 PM  
SKY (%).........19 13 22 17  
WEATHER TYPE....NONE NONE NONE NONE  
TSTM COV........  
CHC OF PCPN (%).10 10 10 0  
TEMP............80 84 91 93  
RH..............88 85 66 54  
20 FT WIND......S 3G13 SW 5G14 S 8G18 S 10G22  
MIX HGT (FT)....500 3000 5000 5700  
TRANSPORT WIND..SW 4 SW 16 SW 18 SW 22  
LVORI...........6 4 1 1  
ADI.............3 55 99 86  
 
 
FORECASTER...BLACK  
REQUESTED BY...MICHAEL LESLIE  
TYPE OF REQUEST...WILDFIRE  
.TAG 2617769.0/CHS  
.DELDT 07/20/26  
.FORMATTERVERSION 2.0.0  
.EMAIL MICHAEL.C.LESLIE@USDA.GOV  
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