688
FNUS75 KBYZ 211037
FWSBYZ

Spot Forecast for Glacier Fire...Forest Service
National Weather Service Billings MT
437 AM MDT Fri Aug 21 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 if you have questions
or concerns with this forecast.

.DISCUSSION...
Wind fields are weak and difficult to get a good handle on. That
said, we expect terrain driven winds under 15 mph early this
morning, switching to the northeast in the afternoon generally
under 15 mph, but there is a slight chance of occasional gusts
20-25 mph in early to mid afternoon. Humdity is expected to drop
into the 20s during the day. Weather is generally quiet this
evening and overnight, but a disturbance brings a line of showers
into the fire vicinity after 6 AM Saturday morning. Scattered
showers and isolated thunderstorms are possible in the afternoon.
Southwest winds should be main direction Saturday...but erratic
stronger gusts possible near showers. BT

.TODAY...

Sky/weather.........Mostly sunny.
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....72-76.
Min humidity........23-29 percent.
Wind (20 ft)........
 Slope/valley.......Terrain driven winds early 7-12 mph. Shifting to the
                    northeast 7 to 11 mph in the afternoon.
 Ridgetop...........Northwest around 10 mph.
Mixing height.......600 ft AGL early in the morning increasing to
                    6000 ft AGL in the afternoon.
Transport winds.....Northwest around 11 mph.

.TONIGHT...

Sky/weather.........Mostly cloudy. Very slight chance of a rain shower in
                    the evening...isolated showers after 4 AM.
CWR.................0 percent.
Chance of lightning.3 percent.
Min temperature.....53-57.
Max humidity........43-47 percent.
Wind (20 ft)........
 Slope/valley.......North winds 7 to 12 mph in the evening becoming
                    light.
 Ridgetop...........Southeast around 5-10 mph.
Mixing height.......4000 ft AGL early in the evening decreasing to
                    500 ft AGL overnight.
Transport winds.....West around 9 mph.

.SATURDAY...

Sky/weather.........Mostly cloudy. Chance of rain showers and isolated
                    of thunderstorms in the afternoon.
CWR.................20 percent.
Chance of lightning.35 percent.
Max temperature.....70-74.
Min humidity........38-46 percent.
Wind (20 ft)........
 Slope/valley.......Southwest winds 6 to 12 mph. Gusty and erratic
                    winds expected near thunderstorms in the
                    afternoon.
 Ridgetop...........Southwest around 15 mph.
Mixing height.......500 ft AGL early in the morning increasing to
                    4700 ft AGL in the afternoon.
Transport winds.....Southwest around 13 mph.

$$
Forecaster...Tesar
Requested by...IC Trainee Thompson
Type of request...WILDFIRE
.TAG 2620140.0/BYZ
.DELDT 08/21/26
.FormatterVersion 2.0.0
.EMAIL mtbdc@firenet.gov