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