765
FNUS76 KOTX 162007
FWSOTX

Spot Forecast for Upper Smith...USFS
National Weather Service Spokane WA
107 PM PDT Sun Aug 16 2026

Forecast is based on forecast start time of 1300 PDT on August 17.
.DISCUSSION...

209:
A warm and relatively moist air mass remained over the fire on Sunday.
Excellent humidity recoveries in the morning gave way to afternoon
temperatures in the 70s to low 80s.  Afternoon heating in concert with
a weak midlevel wave resulted in numerous cumulus buildups, some which
matured into showers and thunderstorms.  Winds were light with speeds less
than 10 mph away from thunderstorm outflows that reached close to 25 mph.

The air mass will remain mild with a subtle drying trend Monday through
Wednesday.  The threat for afternoon showers and thunderstorms will lower
through the week closer to 10-15%.  Winds will be light and mainly terrain
driven with increasing southerly breezes near the US 95 corridor on
Wednesday.

Discussion:
Expect a subtle warming and drying trend the next several days.
There remains a 15% chance for afternoon showers and thunderstorms
Monday (1300-2000) which decreases to 5-10% on Tuesday.  Any thunderstorms
that do develop afternoon will be capable of producing brief heavy
downpours and gusty, erratic winds. Winds will generally be light and
terrain driven away from thunderstorm outflows. Exposed east aspect facing
the Kootenay River could see slightly strong winds Monday afternoon from
the north/northeast. On Tuesday, midlevel winds increase slightly from
the southwest. This is reflected in the transport winds and would only
impact the highest ridges.


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

.MONDAY...

Sky/weather.........Partly sunny. 15% chance for showers and
                    thunderstorms between 1300-2000.  Patchy smoke.
CWR.................10 percent.
Chance of lightning.15 percent.
Max temperature.....77-83.
Min humidity........31-36 percent.
Wind (20 ft)........Upslope/upvalley or east/northeast 3 to 6 mph.
                    Locally 5 to 10 mph on slopes facing the Kootenay
                    River.
Mixing height.......7500 ft AGL.
Transport winds.....Southwest around 9 mph.
Ventilation Index...High (668).

.MONDAY NIGHT...

Sky/weather.........Partly to mostly cloudy.
CWR.................0 percent.
Chance of lightning.0 percent.
Min temperature.....51-56.
Max humidity........50-55 percent.
Wind (20 ft)........Downslope/downvalley 1 to 4 mph.
Mixing height.......4500 ft AGL falling to near surface.
Transport winds.....West 5 mph.
Ventilation Index...Moderate (346) decreasing to low (25)
                    overnight.

.TUESDAY...

Sky/weather.........Mostly sunny becoming partly cloudy with a
                    5-10% chance for afternoon showers/thunderstorms.
CWR.................5 percent.
Chance of lightning.5 percent.
Max temperature.....78-84.
Min humidity........29-34 percent.
Wind (20 ft)........Upslope/upvalley or east/northeast 3 to 6 mph.
Mixing height.......7500 ft AGL in the afternoon.
Transport winds.....Southwest 8-10 mph.
Ventilation Index...Moderate (281) increasing to high (799) in the
                    afternoon.

$$
Forecaster...SB
Requested by...David Pearson
Type of request...WILDFIRE
.TAG 2619090.11/OTX
.DELDT 08/16/26
.FormatterVersion 2.0.0
.EMAIL david_pearson@firenet.gov,IDCDC@firenet.gov,2026.uppersmith.plans@firenet.gov