558
FNUS75 KBOI 202213
FWSBOI

Spot Forecast for Second Flat Coleman Creek Jackass Butte and...DOI
National Weather Service Boise ID
413 PM MDT Thu Aug 20 2026

Forecast is based on forecast start time of 0700 MDT on August 21.
If conditions become unrepresentative...contact the National Weather
Service.

Please contact our office at (208)334-9060, if you have questions
or concerns with this forecast.

...FIRE WEATHER WATCH IN EFFECT FROM SATURDAY AFTERNOON THROUGH
SATURDAY EVENING FOR LOW RH AND WIND...
...HOT AND DRY THROUGH FRIDAY...
...THUNDERSTORM CHANCE FRIDAY NIGHT AND SATURDAY EVENING...
...COOLER TEMPS AND BREEZY WINDS DUE TO A COLD FRONT THIS WEEKEND...

.DISCUSSION...
Upper level trough approaching from the west will continue the
influx of monsoonal moisture for Friday and Saturday. Clouds will
limit daytime temperatures a bit on Friday but not enough to
significant cool the 8 to 10 degree above normal temperatures. Of
greater concern is the potential for thunderstorms and outflow
winds across all fires Friday evening. Development looks to begin
around 4 PM PDT with outflow winds up to 50 MPH pushing south to
north across much of southeast Oregon through sunset. At the
moment, Second Flat and Jackass fires have the highest chance
(20%) for lightning Friday evening with all fires have the same
chance (40%) of seeing outflow winds up to 50 MPH.

A slight chance of thunderstorms early Saturday followed by gusty
winds and low RHs behind the cold frontal passage Saturday
afternoon. Based on the latest frontal timing, the highest chance
for thunderstorms looks to be on the Coleman Creek and Bald
Mountain fires Saturday morning. A fire weather watch has been
issued for westerly winds 15 to 25 mph with gusts to 35 mph with
RHs in the low teens covering all fires except the Coleman Creek
fire. Current forecast is mainly representive of the Coleman Creek
Fire. Should you need greater forecast detail for operations on a
specific fire please submit a spot for that fire.


.FRIDAY...

Sky/weather.........Cloudy.
Max temperature.....85 to 95.
Min humidity........8 to 18 percent.
CWR.................0 percent.
Wind - 20 foot......South 8 to 14 mph. Gusts up to 14 mph in the
                    morning increasing to 20 mph in the afternoon.
Mixing height.......10500 ft AGL.
Transport winds.....South around 15 mph.
Ventilation Index...1575 excellent.

.FRIDAY NIGHT...

Sky/weather.........Cloudy. A 20 percent chance of showers and
                    thunderstorms in the evening. Some
                    thunderstorms may produce gusty winds in the
                    evening.
Min temperature.....60 to 70.
Max humidity........30 to 40 percent.
CWR.................10 percent.
Wind - 20 foot......West 13 to 19 mph with gusts to around 30 mph.
                    Gusty and erratic winds expected near
                    thunderstorms in the evening.
Mixing height.......200 ft AGL.
Transport winds.....Southwest around 10 mph.
Ventilation Index...20 poor.

.SATURDAY...

Sky/weather.........Cloudy in the morning then becoming partly
                    sunny in the afternoon. A 20 percent chance of
                    showers and thunderstorms.
Max temperature.....81 to 91.
Min humidity........8 to 15 percent.
CWR.................10 percent.
Wind - 20 foot......Southwest 14 to 20 mph. Gusts up to 24 mph in
                    the morning increasing to 30 mph in the
                    afternoon. Gusty and erratic winds expected
                    near thunderstorms.
Mixing height.......10500 ft AGL.
Transport winds.....Southwest around 20 mph.
Ventilation Index...2100 excellent.

$$
Forecaster...Smith
Requested by...Travis Clapp
Type of request...WILDFIRE
.TAG 2620118.0/BOI
.DELDT 08/21/26
.FormatterVersion 2.0.0
.EMAIL travis_clapp@ios.doi.gov