939
FNUS76 KOTX 311944
FWSOTX

Spot Forecast for Upper Smith South...Upper Smith
National Weather Service Spokane WA
1244 PM PDT Mon Aug 31 2026

Forecast is based on forecast start time of 0600 PDT on September 01.
.DISCUSSION...

209: Warmer and drier conditions were observed Monday with highs
in the 60s and 70s. Relative humidity recoveries Monday morning
were good to excellent. Minimum relative humidity values were in
the 40 to 50 percent range. Winds were terrain driven.

Temperatures trend warmer and drier on Tuesday. Winds will be
from the east in the morning before increasing and shifting to the
south to southwest in the afternoon. Chances for thunderstorms
begin to increase mid Tuesday afternoon into the evening.
Thunderstorms will initially be drier with gusty outflow winds,
becoming wetter Tuesday night into Wednesday. Through 5AM
Thursday, rain amounts will range between 0.15 to 1 inch. Rain
chances continue into Thursday with a 90% chance of a wetting
rain (greater than 0.10 inches in 12 hours).

Spot Discussion: Temperatures trend warmer and drier on Tuesday.
Active weather returns Tuesday night into Wednesday with chances
for showers and thunderstorms increasing later Tuesday afternoon
and continuing through the weekend. There is very high confidence
for wetting rains Wednesday through Friday over the fires. Winds
will increase out of the south to southwest Tuesday and Wednesday
afternoons. Gusty outflow winds up to 35-40 mph will be a concern
with thunderstorms.

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).
***************************************************************

.TUESDAY...

Sky/weather.........Mostly sunny. 10% chance of showers and thunderstorms
                    between 1400-1700.
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....Ridgetops........69.
                    Valley bottoms...80.
Min humidity........25-30 percent.
Wind (20 ft)........Ridgetops........East 5 to 9 mph in the morning
                    shifting to the south 7 to 11 mph around 1300.
                    Valley bottoms...East 1 to 3 mph in the morning
                    shifting to the south to southwest 2 to 4 mph
                    around 1300.
                    Gusty and erratic winds with any thunderstorms.
Mixing height.......Inversion lifting around 0900 with mixing height around
                    2000 ft AGL until 1200. Increasing to 6000 ft AGL
                    after 1200.
Transport winds.....East around 5 mph shifting to the south around
                    13 mph in the afternoon.
Ventilation Index...Low (96) increasing to high (787) in the
                    afternoon.

.TUESDAY NIGHT...

Sky/weather.........Mostly cloudy. 30% chance of rain showers in
                    the evening increasing to 50% chance overnight.
                    10% chance of thunderstorms overnight.
CWR.................10 percent.
Chance of lightning.10 percent.
Min temperature.....Ridgetops.......42.
                    Valley Bottom...47.
Max humidity........85-90 percent.
Wind (20 ft)........South to southwest 4 to 9 mph. Gusty and erratic winds
                    expected near thunderstorms.
Mixing height.......3000 ft AGL falling to near the surface between
                    1900-2000 hours.
Transport winds.....Southwest 7 to 11 mph.
Ventilation Index...Moderate (451) decreasing to low (31)
                    overnight.

.WEDNESDAY...

Sky/weather.........Mostly cloudy. 80% chance of rain showers in the
                    morning and afternoon. 20% chance of thunders in
                    the afternoon.
CWR.................75 percent.
Chance of lightning.20 percent.
Max temperature.....Ridgetops.......47.
                    Valley Bottom...59.
Min humidity........65-70 percent.
Wind (20 ft)........South to southwest 6 to 11 mph. Gusty and erratic winds
                    expected near thunderstorms in the afternoon.
Mixing height.......3000 ft AGL in the afternoon.
Transport winds.....Southwest 7 to 14 mph.
Ventilation Index...Low (146) increasing to moderate (401) in the
                    afternoon.

$$
Forecaster...VT
Requested by...Wendy
Type of request...WILDFIRE
.TAG 2620106.11/OTX
.DELDT 08/31/26
.FormatterVersion 2.0.0
.EMAIL idcdc@firenet.gov,2026.uppersmith.plans@firenet.gov