800
FNUS75 KTFX 261335
FWSTFX

Spot Forecast for Twin Sisters Fire...USFS
National Weather Service Great Falls MT
735 AM MDT Sun Jul 26 2026

Forecast is based on forecast start time of 0800 MDT on July 26.
If conditions become unrepresentative...contact the National Weather
Service.

.DISCUSSION...

Southwesterly flow aloft on the western periphery of an upper level
ridge will result in continued hot temperatures and low relative
humidity through Monday. While low probability (Largely 15% or
so), any shower or thunderstorm in the vicinity of the wildfire
this afternoon and early evening will be capable of producing
erratic wind gusts well away from where the precipitation is
occurring.

.REST OF TODAY...

Sky/weather.........Sunny (15-25 percent).Increasing clouds late
                    afternoon with a slight chance for a shower
                    or thunderstorm after 4 PM.
CWR.................5 percent.
Chance of thunder...15 percent.
Max temperature.....88-93.
Min humidity........15-20 percent.
Wind (20 ft)........
 Slope/valley.......Up slope/valley around 5 mph through late morning,
                    becoming south to southwest around 5-10 mph, with
                    gusts up to 20 mph in the afternoon
 Ridgetop...........Southwest 15 to 20 mph shifting to the south
                    late in the afternoon.
Mixing height.......7500 ft AGL.
Transport winds.....Light and variable through the morning, then
                    shifting to the south 15 to 20 mph in the
                    afternoon.

TIME (MDT)      8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........12  21  14  23  17  16  14  9   32  32
Weather cov.....                                RW  RW
Weather type....                                SCH SCH
Tstm cov........                                SCH SCH
CWR.............0   0   0   0   0   0   0   0   5   5
Chc of thdr (%).0   0   0   0   0   0   0   0   15  15
Temp............71  73  77  80  82  85  87  88  88  89
RH..............31  29  27  25  23  22  19  17  18  21
20 FT wind dir..N   N   NE  E   SE  SE  S   S   S   S
20 FT wind spd..5   5   5   5   10  15  15  15  15  15
20 FT wind gust.10  10  10  15  20  25  30  30  30  25
Ridge wind dir..W   SW  SW  SW  SW  SW  SW  W   SW  S
Ridge wind spd..15  15  15  15  15  15  20  20  15  15
Mix hgt (kft)...1.0 1.5 2.0 2.5 4.0 5.0 6.0 7.5 7.0 6.5
Transp wind dir.N   N   N   E   S   S   S   S   S   S
Transp wind spd.10  10  5   10  15  15  20  20  20  15

.TONIGHT...

Sky/weather.........Partly cloudy (20-30 percent). Slight chance of
                    thunderstorms early in the evening.
CWR.................10 percent.
Chance of thunder...15 percent.
Min temperature.....61-66.
Max humidity........28-33 percent.
Wind (20 ft)........
 Slope/valley.......Southwest winds 5 to 10 mph through sunset,
                    becoming downslope/valley around 5 mph.
                    Northwest wind 5-10 mph after 3 AM.
 Ridgetop...........South 10 to 15 mph becoming light/variable.
Mixing height.......500 ft AGL.
Transport winds.....South 10 to 15 mph shifting to the northwest
                    overnight.

TIME (MDT)      6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........25  43  25  25  25  11  9   20  20  20  13  19
Weather cov.....SCH SCH SCH SCH SCH
Weather type....RW  RW  RW  RW  RW
Tstm cov........SCH SCH SCH
CWR.............10  10  10  10  10  10  0   0   0   0   0   0
Chc of thdr (%).20  20  20  10  10  0   0   0   0   0   0   0
Temp............88  85  82  75  72  71  70  70  69  66  65  65
RH..............22  24  28  31  32  32  32  32  32  33  33  32
20 FT wind dir..S   S   SW  SW  SW  SW  SW  W   W   NW  NW  NW
20 FT wind spd..15  15  10  10  10  10  10  10  10  10  10  15
20 FT wind gust.25  20  15  15  15  15  15  15  15  15  15
Ridge wind dir..S   S   S   SE  SE  S   S   S   SE  SE  E   N
Ridge wind spd..10  10  10  10  10  15  15  15  10  5   5   5
Mix hgt (kft)...5.0 3.5 1.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Transp wind dir.S   S   S   S   S   S   SW  SW  NW  N   N   NW
Transp wind spd.15  15  10  10  10  10  10  10  10  10  15  15

.MONDAY...

Sky/weather.........Mostly sunny (25-35 percent).
CWR.................0 percent.
Chance of thunder...1 percent.
Max temperature.....86-91.
Min humidity........14-19 percent.
Wind (20 ft)........
 Slope/valley.......Northwest winds 10 to 15 mph shifting to the
                    east late in the afternoon.
 Ridgetop...........Light and variable, becoming southwest 10 mph
                    in the afternoon.
Mixing height.......10500 ft AGL.
Transport winds.....North 10 to 15 mph shifting to the southwest 15
                    to 20 mph in the afternoon.

TIME (MDT)      6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........37  37  37  25  25  25  25  25  25  28  28  28
Weather cov.....
Weather type....
Tstm cov........
CWR.............0   0   0   0   0   0   0   0   0   0   0   0
Chc of thdr (%).0   0   0   0   0   0   0   0   0   0   0   0
Temp............64  67  70  72  77  79  80  82  86  86  87  88
RH..............31  29  27  24  24  23  21  21  19  19  19  19
20 FT wind dir..NW  NW  N   N   N   NE  NE  NE  E   E   E   SE
20 FT wind spd..15  10  10  10  10  10  10  10  10  10  10  10
20 FT wind gust.    15  15  15  15  15  20  20  20  20  20  20
Ridge wind dir..N   NW  W   W   W   SW  SW  SW  SW  SW  SW  SW
Ridge wind spd..5   0   0   5   5   5   5   5   10  15  15  15
Mix hgt (kft)...0.5 0.5 1.0 2.0 2.5 3.0 3.5 6.5 9.5 7.5 11  8.5
Transp wind dir.NW  N   N   N   N   N   N   SW  SW  SW  SW  SW
Transp wind spd.15  15  15  10  10  10  10  15  15  15  20  15

$$
Forecaster...McDowell
Requested by...Clifford Reynolds
Type of request...WILDFIRE
.TAG 2618277.0/TFX
.DELDT 07/26/26
.FormatterVersion 2.0.0
.EMAIL clifford.reynolds@usda.gov, tfx.ops@noaa.gov, mt.hdc@firenet.gov