846
FNUS75 KBYZ 011006
FWSBYZ

Spot Forecast for North Derby Unit 3...USFS
National Weather Service Billings MT
406 AM MDT Thu Oct 1 2026

Forecast is based on ignition time of 1000 MDT on October 01.
If conditions become unrepresentative...contact the National Weather
Service.

Please contact our office if you have questions
or concerns with this forecast.

.DISCUSSION...
Look for variable cloudiness across the burn site today.
Conditions are still expected to be cooler with easterly winds
prevailing. RH readings are only expected to drop to around 50-55%
range by mid afternoon. RH recoveries will be above 65% tonight.
Winds should turn a little more southwesterly late tonight into
Friday. Friday will be mostly sunny and warmer, and humidity
dropping into the 20s. Winds will be west/northwest with some
gusty conditions in the afternoon, but not as strong as Wednesdays.
BT


.TODAY...

Sky/weather.........Partly sunny.
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....53-57.
Min humidity........50-55 percent.
Wind (20 ft)........
 Slope/valley.......East/southeast winds 5-7 mph early, 6-9 mph with a few gusts
                    to 13-16 mph in the afternoon.
 Ridgetop...........West around 15 mph.
Mixing height.......1400 ft AGL early in the morning increasing to
                    3300 ft AGL in the afternoon.
Transport winds.....East 7 to 9 mph.

TIME (MDT)      10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........35  36  35  27  39  31  39  44
Weather cov.....
Weather type....
Tstm cov........
Chc of ltng (%).0   0   0   0   0   0   0   0
Temp............46  47  49  52  54  55  55  54
RH..............72  70  65  62  56  54  54  54
20 FT wind dir..SE  E   E   E   E   E   E   E
20 FT wind spd..6   6   6   6   7   8   8   7
20 FT wind gust.7   10  12  13  13  14  14  12

.TONIGHT...

Sky/weather.........Partly cloudy.
CWR.................0 percent.
Chance of lightning.0 percent.
Min temperature.....39-45.
Max humidity........70-76 percent.
Wind (20 ft)........
 Slope/valley.......Southeast winds up to 7 mph in the evening
                    becoming light, then becoming southwest up to 6
                    mph after 3 am.
 Ridgetop...........South around 5 mph.
Mixing height.......2100 ft AGL early in the evening decreasing to
                    400 ft AGL overnight.
Transport winds.....Southeast 7 to 10 mph shifting to the southwest
                    6 to 8 mph overnight.

TIME (MDT)      6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........47  51  44  42  28  44  49  46  58  59  51  47
Weather cov.....
Weather type....
Tstm cov........
Chc of ltng (%).0   0   0   0   0   0   0   0   0   0   0   0
Temp............53  51  48  47  46  45  45  45  44  44  45  42
RH..............55  60  66  69  71  72  73  73  70  67  66  67
20 FT wind dir..E   SE  SE  SE  SE  S   S   S   SW  W   W   SW
20 FT wind spd..7   7   7   7   6   5   4   4   4   4   5   6
20 FT wind gust.11  11  12  13  10  7   6   6   6   6   6   7

.FRIDAY...

Sky/weather.........becoming mostly sunny.
CWR.................0 percent.
Chance of lightning.0 percent.
Max temperature.....68-72.
Min humidity........23-27 percent.
Wind (20 ft)........
 Slope/valley.......West winds 7-10 mph with afternoon gusts 16-22 mph.
 Ridgetop...........Northwest around 12 mph.
Mixing height.......increasing to 7400 ft AGL in the afternoon.
Transport winds.....West 9 to 13 mph increasing to 13 to 17 mph
                    in the afternoon.

TIME (MDT)      6 AM      9 AM      NOON      3 PM
Sky (%).........51        22        32        23
Weather cov.....
Weather type....NONE      NONE      NONE      NONE
Tstm cov........
Chc of ltng (%).0         0         0         0
Temp............45        53        64        70
RH..............61        49        36        24
20 FT wind......SW 6G10   W 6G11    NW 7G14   W 8G17

$$
Forecaster...Tesar
Requested by...Greg Oyler
Type of request...PRESCRIBED
.TAG 2622650.4/BYZ
.DELDT 10/01/26
.FormatterVersion 2.0.0
.EMAIL gregory.oyler@usda.gov