955
FNUS75 KCYS 201855
FWSCYS

Spot Forecast for Brittania Mountain...Casper Interagency Dispatch
National Weather Service Cheyenne WY
1255 PM MDT Thu Aug 20 2026

If conditions become unrepresentative, contact the National Weather
Service at (307) 772-2227

.DISCUSSION...

Warm and dry conditions will continue through this afternoon with a
temperature in the mid 80s and a minimum relative humidity around
15 percent. Winds will remain relatively light into the evening hours.
There is a slight chance of showers this evening, mainly between 9 PM
and 12 AM. Showers could contains gusty and erratic winds. Overnight
humidity recoveries will be rather poor, with a maximum humidity
around 45 percent. Another warm day is expected Friday with highs in
the upper 80s. Minimum relative humidity will once again be near 15
percent. Winds will be out of the north to northwest at around 10 MPH.
There is a slight chance of a stray shower during the afternoon
which could contain occasional lightning and gusty winds.

.REST OF TODAY...

Sky/weather.........Sunny (5-15 percent).
CWR.................0 percent.
Max temperature.....Around 83.
Min humidity........16 percent.
Wind (20 ft)........Northwest winds 5 to 7 mph.
Mixing height.......11600 ft AGL.
Transport winds.....Northwest 15 to 17 mph.
Smoke dispersal..... very good (126400 knot-ft) early in the
                    morning increasing to excellent (174100
                    knot-ft) in the afternoon.

TIME (MDT)      1PM 2PM 3PM 4PM 5PM
Sky (%).........6   8   13  13  9
Weather cov.....
Weather type....
Tstm cov........
CWR.............0   0   0   0   0
Temp............80  82  83  82  82
RH..............20  18  17  17  17
20 FT wind dir..W   NW  NW  NW  NW
20 FT wind spd..5   5   6   6   7
20 FT wind gust.8   9   10  10  12
Mix hgt (kft)...9.7 11  11  12  12
Transp wind dir.W   W   NW  NW  NW
Transp wind spd.15  15  17  17  16
SDspl kt-ft/1000126 139 167 174 162

.TONIGHT...

Sky/weather.........Mostly clear (20-30 percent).
CWR.................2 percent.
Min temperature.....Around 62.
Max humidity........43 percent.
Wind (20 ft)........Northwest winds around 7 mph shifting to the
                    southwest 7 to 9 mph late in the evening.
Mixing height.......500 ft AGL.
Transport winds.....Northwest around 12 mph shifting to the east
                    around 8 mph early in the evening, then
                    shifting to the south 9 to 12 mph late in the
                    evening shifting to the southwest 10 to 15 mph
                    overnight.
Smoke dispersal.....Good (93600 knot-ft) early in the evening
                    decreasing to poor (3500 knot-ft) late in the
                    night.

TIME (MDT)      6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........9   13  14  22  17  29  28  37  33  27  30  34
Weather cov.....
Weather type....
Tstm cov........
CWR.............0   0   0   0   0   0   0   0   0   0   0   0
Temp............82  80  76  71  70  69  68  67  65  64  63  63
RH..............16  19  23  28  30  32  36  37  40  43  43  39
20 FT wind dir..N   NW  NW  W   SW  SW  S   SW  SW  SW  W   W
20 FT wind spd..7   7   7   7   7   7   7   7   8   8   9   9
20 FT wind gust.12  13  13  13  14  14  14  15  15  16  16  17
Mix hgt (kft)...9.4 2.0 0.5 0.5 0.5 0.5 0.6 0.5 0.6 0.5 0.5 0.5
Transp wind dir.NW  E   E   SE  S   S   S   SW  W   W   SW  W
Transp wind spd.12  8   8   9   9   12  10  10  12  13  13  15
SDspl kt-ft/100094  14  4   4   4   5   5   5   6   6   5   7

.FRIDAY...

Sky/weather.........Mostly sunny (30-40 percent).
CWR.................2 percent.
Max temperature.....Around 87.
Min humidity........16 percent.
Wind (20 ft)........West winds 7 to 9 mph shifting to the north
                    around 7 mph late in the afternoon.
Mixing height.......7700 ft AGL increasing to 12400 ft AGL in the
                    afternoon.
Transport winds.....West 14 to 16 mph shifting to the northwest 13
                    to 14 mph late in the afternoon.
Smoke dispersal.....Poor (6500 knot-ft) early in the morning
                    increasing to good (99900 knot-ft) in the
                    afternoon increasing to very good (111900
                    knot-ft) in the afternoon.

TIME (MDT)      6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........31  35  31  28  25  23  21  36  51  44  49  38
Weather cov.....
Weather type....
Tstm cov........
CWR.............0   0   0   0   0   0   0   0   0   0   0   0
Temp............62  65  69  71  77  83  85  85  87  84  83  86
RH..............39  34  30  29  24  19  17  17  16  17  18  16
20 FT wind dir..W   W   W   W   W   W   W   NW  NW  N   N   N
20 FT wind spd..9   9   9   8   8   8   7   7   7   7   7   7
20 FT wind gust.17  17  17  16  16  15  15  14  14  14  14  13
Mix hgt (kft)...0.5 0.5 0.5 0.9 3.1 7.7 11  12  12  10  12  11
Transp wind dir.W   W   W   W   W   W   NW  NW  NW  NW  NW  NW
Transp wind spd.16  16  15  15  15  15  15  14  14  13  13  14
SDspl kt-ft/10007   7   7   12  41  100 137 145 149 112 127 135

$$
Forecaster...Fuller
Requested by...S.Daubin
Type of request...WILDFIRE
.TAG 2620097.0/CYS
.DELDT 08/20/26
.FormatterVersion 2.0.0
.EMAIL burke.lee.r@gmail.com