358
FNUS75 KSLC 140223
FWSSLC

Spot Forecast for Haystack Fire...USFS
National Weather Service Salt Lake City UT
823 PM MDT Wed Aug 13 2025

Forecast is based on forecast start time of 0700 MDT on August 14.
If conditions become unrepresentative...contact the National Weather
Service.

...RED FLAG WARNING IN EFFECT FROM NOON TO 9 PM MDT THURSDAY...

.DISCUSSION...Midlevel moisture will continue to spread north into
Utah for Thursday and Friday, leading to scattered showers and
thunderstorms. On Thursday afternoon, these initial showers and
thunderstorms will likely remain high-based, so expect little in
the way of rainfall but strong gusty outflow winds with gusts in
excess of 40 mph will be possible. As the airmass continues to
trend more moist, wetting rain chances will increase for Friday,
but not significantly. As such, strong, gusty outflow winds will
remain a threat on Friday as well. Outside of showers and
thunderstorms, winds will remain relatively light. Expect
temperatures to trend gradually cooler and humidities higher
through the end of the week.


.THURSDAY...

Sky/weather.........Partly cloudy (30-40 percent cloud cover) then
                    becoming mostly cloudy (65-75 percent cloud
                    cover). Rain showers likely and a chance of
                    thunderstorms in the afternoon.
CWR.................10 percent.
Chance of pcpn......60 percent.
Chance of lightning.30 percent.
Max temperature.....72-75.
Min humidity........21-24 percent.
Wind (20 ft)........West winds 2-5 mph becoming southwest 4-9 mph
                    after noon. Gusty and erratic winds expected near
                    thunderstorms in the afternoon.
Mixing height.......10000 ft AGL.
   Climatology......70-80th Percentile.
Transport winds.....West 17 to 18 mph.

.THURSDAY NIGHT...

Sky/weather.........Partly cloudy (45-55 percent cloud cover).
                    Chance of rain showers and slight chance of
                    thunderstorms in the evening, then slight
                    chance of rain showers overnight.
CWR.................15 percent.
Chance of pcpn......40 percent.
Chance of lightning.15 percent.
Min temperature.....51-54.
Max humidity........46-49 percent.
Wind (20 ft)........Southwest winds 4-8 mph becoming southeast 2-5
                    mph after 2200. Gusty and erratic winds expected
                    near thunderstorms early in the evening.
Mixing height.......0 ft AGL.
Transport winds.....West around 15 mph becoming south around 8 mph
                    overnight.

.FRIDAY...

Sky/weather.........Partly cloudy (45-55 percent cloud cover).
                    Chance of showers and thunderstorms in the
                    afternoon.
CWR.................15 percent.
Chance of pcpn......50 percent.
Chance of lightning.30 percent.
Max temperature.....68-71.
Min humidity........26-29 percent.
Wind (20 ft)........Southeast winds 2-5 mph becoming southwest 5-9
                    mph after 1000. Gusty and erratic winds expected
                    near thunderstorms in the afternoon.
Mixing height.......8600 ft AGL.
   Climatology......60-70th Percentile.
Transport winds.....Southwest around 12 mph becoming southeast
                    around 14 mph in the afternoon.

$$
Forecaster...Cheng
Requested by...Roman Valdez
Type of request...WILDFIRE
.TAG 2519867.0/SLC
.DELDT 08/13/25
.FormatterVersion 2.0.0
.EMAIL roman.valdez@usda.gov,utnuc@firenet.gov