Spot Forecast
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
140
FNUS75 KRIW 202308
FWSRIW
Spot Forecast for Telephone...USFS SHF
National Weather Service Riverton WY
508 PM MDT Sun Sep 20 2026
Forecast is based on forecast start time of 0600 MDT on September 21.
If conditions become unrepresentative, contact the National Weather
Service
.DISCUSSION...
Conditions will remain dry Monday. There could be some low
clouds/fog through 0800, then mostly sunny. Partly cloudy skies
will develop after 1400. South winds, 10 to 15 mph, will also
develop around this time, decreasing below 10 mph by 1900. Clouds
will increase over the site around sunrise Tuesday morning, with
conditions remaining dry through most of the day. Showers and
thunderstorms will be possible between 1600 and 1800, with a
broader area of showers moving over the site after 2200 Tuesday
night.
...Thunderstorms imply strong gusty and erratic winds...
.MONDAY...
Sky/weather.........Sunny (15-25 percent). Areas of fog early in
the morning.
CWR.................0 percent.
Chance of pcpn......0 percent.
Chance of thunder...2 percent.
Max temperature.....Around 63.
Min humidity........46 percent.
Wind (20 ft)........Light winds until 1500, then south around 7 mph
with gusts to around 16 mph until 1700, then
light.
Ridgetop wind.......Light winds until 1200, then south 10 to 15
mph.
Mixing height.......1000 ft AGL until 1000. 5000 ft AGL after 1300.
Transport winds.....North around 7 mph until 1000, then light until
1100, then southwest 7 to 14 mph.
Smoke dispersal.....Poor until 1100. Fair after 1400.
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........25 20 15 15 15 10 15 20 15 20 20 15
Weather cov.....ARS ARS ARS
Weather type....FOG FOG FOG
Tstm cov........
CWR.............0 0 0 0 0 0 0 0 0 0 0 0
Chc of pcpn (%).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............32 31 33 42 51 55 59 60 59 58 59 62
RH..............98 100 99 77 64 54 48 45 46 48 47 44
20 FT wind dir..N N N N W SW S S S S S S
20 FT wind spd..2 2 2 2 1 2 4 5 6 7 7 6
20 FT wind gust.5 5 6 5 5 6 8 10 13 14 16 14
Ridge wind dir..N N N N W SW S S S S S S
Ridge wind spd..5 5 5 5 5 5 10 10 15 15 15 15
Mix hgt (kft)...0.5 0.5 0.5 1.0 2.5 3.0 4.0 4.5 5.0 5.0 4.0 4.0
Transp wind dir.N N N NW SW SW S SW SW SW SW S
Transp wind spd.7 7 7 7 6 7 9 10 13 14 14 13
SDspl kt-ft/10003 3 4 7 12 18 31 39 54 58 51 42
.MONDAY NIGHT...
Sky/weather.........Partly cloudy (25-35 percent).
CWR.................0 percent.
Chance of pcpn......0 percent.
Chance of thunder...2 percent.
Min temperature.....Around 32.
Max humidity........90 percent.
Wind (20 ft)........Light winds.
Ridgetop wind.......Southeast 10 to 15 mph until 2000, then light
until 2400, then north around 10 mph.
Mixing height.......2000 ft AGL until 2000, then 500 ft AGL.
Transport winds.....South 8 to 13 mph until 2000. North 8 to 9 mph
after 0100.
Smoke dispersal.....Poor.
TIME (MDT) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........25 25 25 15 20 20 20 25 30 30 35 40
Weather cov.....
Weather type....
Tstm cov........
CWR.............0 0 0 0 0 0 0 0 0 0 0 0
Chc of pcpn (%).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............60 57 50 47 44 41 40 39 37 37 37 37
RH..............46 51 61 69 74 83 86 90 93 90 87 85
20 FT wind dir..S SE SE SE NE N N N N N N N
20 FT wind spd..6 3 1 2 2 2 3 3 3 3 3 3
20 FT wind gust.13 7 5 5 6 6 6 6 6 7 7 6
Ridge wind dir..S SE SE SE NE N N N N N N N
Ridge wind spd..15 10 5 5 5 5 10 10 10 10 10 10
Mix hgt (kft)...3.0 2.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Transp wind dir.S S SE E E NE N N N N N NW
Transp wind spd.13 8 7 7 7 7 8 8 8 8 9 9
SDspl kt-ft/100034 13 4 3 3 3 4 4 4 4 5 4
.TUESDAY...
Sky/weather.........Mostly sunny (40-50 percent) then becoming
mostly cloudy (70-80 percent).
CWR.................0 percent.
Chance of pcpn......0 percent.
Chance of thunder...4 percent.
Max temperature.....Around 67.
Min humidity........35 percent.
Wind (20 ft)........Light winds until 1500, then southwest around 7
mph with gusts to around 16 mph until 1600,
then light.
Ridgetop wind.......Northwest around 10 mph until 1100, then
southwest.
Mixing height.......1000 ft AGL until 1000, then 4000 ft AGL until
1200, then 6500 ft AGL until 1500, then 7500 ft
AGL until 1600, then 5500 ft AGL.
Transport winds.....Northwest 8 to 10 mph until 1100, then
southwest 13 to 18 mph.
Smoke dispersal.....Poor until 1100, then fair until 1200, then
good. Increasing to very good until 1700, then
fair.
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........50 45 45 40 35 30 25 40 50 60 70 75
Weather cov.....
Weather type....
Tstm cov........
CWR.............0 0 0 0 0 0 0 0 0 0 0 0
Chc of pcpn (%).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............37 36 40 48 55 59 62 63 62 62 62 62
RH..............82 83 76 64 52 42 35 33 34 35 36 36
20 FT wind dir..N N N NW W W SW SW SW SW W W
20 FT wind spd..3 3 3 3 3 4 5 6 6 7 6 6
20 FT wind gust.6 6 6 7 8 10 10 12 14 16 14 13
Ridge wind dir..N N N NW W W SW SW SW SW W W
Ridge wind spd..10 10 10 10 10 10 10 10 15 15 15 10
Mix hgt (kft)...0.5 0.5 0.5 1.0 2.5 4.0 5.5 6.0 6.5 7.5 5.5 4.0
Transp wind dir.N NW NW NW NW W SW SW SW SW SW W
Transp wind spd.8 9 9 8 10 13 15 16 17 18 16 14
SDspl kt-ft/10004 4 5 6 21 43 72 85 100 116 79 48
.FORECAST DAYS 3 THROUGH 5...
.WEDNESDAY...
Partly cloudy. Chance of showers and slight chance of
thunderstorms. Lows in the mid 30s. Highs in the mid 60s. West-
northwest winds 10-20 mph.
.THURSDAY...
Mostly clear. Lows in the mid 30s. Highs around 70. South winds
5-10 mph.
.FRIDAY...
Mostly clear. Lows in the upper 30s. Highs around 70. Southwest
winds 15-20 mph.
$$
Forecaster...LaVoie
Requested by...Tim Sherwin
Type of request...WILDFIRE
.TAG 2621796.7/RIW
.DELDT 09/20/26
.FormatterVersion 2.0.0
.EMAIL timothy.sherwin@usda.gov,brandon.bonenberger@usda.gov