851
FNUS75 KBOU 041249
FWSBOU

Spot Forecast for Devils Thumb...USFS
National Weather Service Denver/Boulder CO
549 AM MST Thu Dec 4 2025

If conditions become unrepresentative...contact the National Weather
Service.

.DISCUSSION...Clouds and even a couple flurries were trapped in
Middle Park and much of Grand County this morning. Daytime heating
will attempt to break these clouds up, but overall smoke
dispersal may be later to improve. However, with westerly winds
increasing, we expect at least fair smoke dispersion by this
afternoon.

Winds aloft will continue to increase on Friday. There will also
be light snow moving into the area late tonight and Friday. Both
of those elements together will support fair smoke dispersion
for Friday. Heavier snowfall is expected to develop late Friday
night and continue through Saturday.

.REST OF TODAY...

Sky/weather.........Mostly cloudy (60-70 percent) until 1100, then
                    partly cloudy (40-50 percent).
Chance of pcpn......10 percent.
Max temperature.....Around 16.
Min humidity........58 percent.
Wind (20 ft)........West winds 11 to 19 mph with gusts to around 30
                    mph.
Mixing height.......Below 1000 FT AGL until 1200, then 1400 ft AGL
                    until 1600, then Below 1000 FT AGL.
Transport winds.....West 15 to 24 mph until 1200, then 23 to 28
                    mph.
Smoke dispersal.....Poor.

TIME (MST)      7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........57  60  54  48  46  41  40  42  47  57  62
Weather cov.....                PTY PTY PTY PTY PTY PTY PTY
Weather type....                BSN BSN BSN BSN BSN BSN BSN
Tstm cov........
Chc of pcpn (%).10  10  10  10  10  10  10  10  10  10  10
Temp............2   1   4   7   9   11  13  14  15  16  14
RH..............91  95  87  79  76  73  67  64  61  58  64
20 FT wind dir..W   W   W   W   W   W   W   W   W   W   W
20 FT wind spd..14  15  16  18  21  22  23  23  23  23  22
20 FT wind gust.22  24  25  30  33  35  35  35  35  35  35
Mix hgt (kft)...0.1 0.1 0.1 0.3 0.8 1.4 1.4 1.4 1.4 0.3 0.1
Transp wind dir.W   W   W   W   W   W   W   W   W   W   W
Transp wind spd.15  15  20  23  24  26  28  28  28  25  23
Vrate kt-ft/1K..0   0   0   6   16  40  42  42  40  8   2
SmokeDispersion.P   P   P   P   P   F   F   F   F   P   P

.TONIGHT...

Sky/weather.........Mostly cloudy (65-75 percent). Patchy blowing
                    snow until 0500Areas of blowing snow after
                    0500. Slight chance of snow after 2000 until
                    2300, then chance of snow until 0200, then snow
                    likely.
Chance of pcpn......70 percent.
Min temperature.....Around 4 above.
Max humidity........100 percent.
Wind (20 ft)........West winds 20 to 28 mph with gusts to around 37
                    mph.
Mixing height.......Below 1000 FT AGL.
Transport winds.....West 21 to 26 mph.
Smoke dispersal.....Poor.

TIME (MST)      6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........62  56  55  57  57  60  60  59  70  72  78  84
Weather cov.....PTY PTY SCH SCH SCH CHC CHC CHC LKY LKY LKY LKY
Weather type....BSN BSN SN  SN  SN  SN  SN  SN  SN  SN  SN  SN
Tstm cov........
Chc of pcpn (%).10  10  20  20  20  40  40  40  60  60  60  70
Temp............10  7   5   4   5   5   4   4   4   5   5   6
RH..............76  87  87  95  87  87  91  95  95  91  95  96
20 FT wind dir..W   W   W   W   W   W   W   W   W   W   W   W
20 FT wind spd..23  23  24  24  24  24  24  23  23  23  23  23
20 FT wind gust.35  35  37  37  37  37  36  35  35  35  35  35
Mix hgt (kft)...0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1 0.1
Transp wind dir.W   W   W   W   W   W   W   W   W   W   W   W
Transp wind spd.24  25  25  25  25  24  23  23  22  22  23  23
Vrate kt-ft/1K..0   0   0   0   0   0   0   0   0   0   0   0
SmokeDispersion.P   P   P   P   P   P   P   P   P   P   P   P

.FRIDAY...

Sky/weather.........Mostly cloudy (80-90 percent). Patchy blowing
snow. Snow likely until 1700. Chance of snow
after 1700.
Chance of pcpn......70 percent.
Max temperature.....Around 13.
Min humidity........91 percent.
Wind (20 ft)........West winds 17 to 25 mph with gusts to around 35
                    mph.
Mixing height.......Below 1000 FT AGL until 1400, then 1200 ft AGL
                    until 1500, then Below 1000 FT AGL.
Transport winds.....West 23 to 29 mph.
Smoke dispersal.....Poor.

TIME (MST)      6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........84  85  85  84  84  83  81  80  80  80  80  80
Weather cov.....LKY LKY LKY LKY LKY LKY LKY LKY LKY LKY LKY CHC
Weather type....SN  SN  SN  SN  SN  SN  SN  SN  SN  SN  SN  SN
Tstm cov........
Chc of pcpn (%).70  70  70  70  70  70  70  70  70  70  70  40
Temp............5   5   6   7   9   10  11  11  12  13  11  10
RH..............100 100 100 100 96  96  96  100 96  91  96  100
20 FT wind dir..W   W   W   W   W   W   W   W   W   W   W   W
20 FT wind spd..22  22  22  21  21  21  21  20  20  20  20  20
20 FT wind gust.35  35  35  33  33  33  33  31  31  31  31  31
Mix hgt (kft)...0.1 0.1 0.1 0.2 0.3 0.4 0.7 1.4 1.4 1.4 0.5 0.2
Transp wind dir.W   W   W   W   W   W   W   W   W   W   W   W
Transp wind spd.24  24  24  24  25  25  26  28  29  26  25  23
Vrate kt-ft/1K..0   0   0   3   6   10  20  42  42  40  11  4
SmokeDispersion.P   P   P   P   P   P   P   F   F   F   P   P

.FORECAST DAYS 3 THROUGH 7...
.SATURDAY...
Breezy, snow. Blowing snow. Lows around 11. Highs around 13. West
winds around 27 mph.
.SUNDAY...
Snow. Blowing snow until 2400. Patchy blowing snow after 2400.
Lows around 7. Highs around 11. West winds around 20 mph.
.MONDAY...
Mostly cloudy. Chance of snow. Lows around 6. Highs around 17.
West winds around 23 mph.
.TUESDAY...
Mostly cloudy with chance of snow. Lows around 12. Highs in the
lower 20s.
.WEDNESDAY...
Mostly cloudy with chance of snow. Lows around 18. Highs in the
lower 20s.

$$
Forecaster...Barjenbruch
Requested by...Tim  Egan
Type of request...PRESCRIBED
.TAG 2526845.2/BOU
.DELDT 12/04/25
.FormatterVersion 2.0.0
.EMAIL timothy.egan@usda.gov