733
FNUS76 KOTX 211350
FWSOTX

Spot Forecast for Ptarmigan...USFS
National Weather Service Spokane WA
650 AM PDT Fri Aug 21 2026

Forecast is based on forecast start time of 0600 PDT on August 21.

...HEAT ADVISORY IN EFFECT FROM 11 AM THIS MORNING TO 10 PM PDT
THIS EVENING...

...FIRE WEATHER WATCH IN EFFECT FROM SATURDAY MORNING THROUGH
SUNDAY MORNING...

.DISCUSSION...

Conditions will be warm and dry Friday with southwest winds less
than 10 mph. High clouds will move into the area through the day
Friday ahead of an approaching storm system. Slight chances for
showers move in late Friday night into early Saturday morning.
Chances for showers increase late Saturday morning through
Saturday afternoon, as do chances for accompanying thunderstorms.
There is a high chance (75 percent) of the fire receiving a
wetting rain (greater than 0.10 inches). Winds increase out of the
southwest Saturday afternoon as the storm system and associated
cold front moves through.

If conditions become unrepresentative, contact the National Weather
Service.
***************************************************************
Forecasts for 20 foot wind speeds (valleys and ridge tops) are
10 minute averages reflecting RAWS wind.
***Ventilation Index is derived from transport wind
   multiplied by the mixing height divided by 100.
   Categories: low (< 200), moderate (200-500),
   high (500-800), and very high (> 800).
***************************************************************

.TODAY...

Sky/weather.........Mostly sunny in the morning becoming mostly
                    cloudy in the afternoon.
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....74-83.
Min humidity........21-26 percent.
Wind (20 ft)........South-southwest winds 5-8 mph.
Mixing height.......Inversion lifting around 0900. Mixing height
                    increasing to 6500 ft AGL in the afternoon.
Transport winds.....South 11-15 mph in the morning becoming
                    southwest 16-20 mph after 1100.
Ventilation Index...Moderate (413) increasing to very high (963) in
                    the afternoon.

.TONIGHT...

Sky/weather.........Cloudy. 20 percent chance of showers after 2000.
CWR.................0 percent.
Chance of lightning.5 percent.
Min temperature.....54-57.
Max humidity........58-63 percent.
Wind (20 ft)........South winds 4-7 mph in the evening becoming
                    variable 1-4 mph after 2200.
Mixing height.......Falling to 500 ft AGL around 1930.
Transport winds.....Southwest 10-13 mph.
Ventilation Index...High (631) decreasing to low (62) overnight.

.SATURDAY...

Sky/weather.........Cloudy in the morning becoming partly sunny in
                    the afternoon. 20 percent chance of showers in
                    the morning increasing to 60 percent after 1400.
                    10 percent chance of thunderstorms in the early
                    morning increasing to a 35 percent chance after
                    1000.
CWR.................75 percent.
Chance of lightning.10 percent in the early morning increasing to 35
                    percent after 1000.
Max temperature.....62-73.
Min humidity........48-53 percent.
Wind (20 ft)........Variable 1-4 mph in the morning becoming
                    south-southwest 8-11 mph with ridgetop winds
                    17-20 mph after 1300. Gusty and erratic winds
                    expected near thunderstorms in the afternoon.
Mixing height.......Inversion lifting around 0900. Mixing height
                    increasing to 4000 ft AGL in the afternoon.
Transport winds.....Southeast 6-9 mph in the morning shifting to
                    the south 17-22 mph in the afternoon.
Ventilation Index...High (775).

$$
Forecaster...RFKS
Requested by...Brian Campbell
Type of request...WILDFIRE
.TAG 2620029.1/OTX
.DELDT 08/21/26
.FormatterVersion 2.0.0
.EMAIL michael.barajas@usda.gov,brian.d.campbell@usda.gov,William.Burks4@usda.gov