Spot Forecast
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
013
FNUS75 KRIW 212309
FWSRIW
Spot Forecast for Telephone...USFS SHF
National Weather Service Riverton WY
509 PM MDT Mon Sep 21 2026
Forecast is based on forecast start time of 0600 MDT on September 22.
If conditions become unrepresentative, contact the National Weather
Service
.DISCUSSION...
Conditions will be dry, with chances for showers and a
thunderstorm increasing by 1500. Showers will be likely by 1800
and continue through 2200 as they move northward. Another wave of
showers will be possible after midnight, but look to stay further
west over Togwotee Pass early Wednesday morning. Skies will be
mostly cloudy to start Tuesday morning, scattering out briefly
late in the morning before the afternoon showers arrive. Winds
will become southwesterly 5 to 15 mph by 1300. Winds will then
have a more westerly component after 2000, staying 5 to 10 mph
through the overnight hours. Skies will stay mostly cloudy
Wednesday morning, gradually scattering out and becoming partly
cloudy/mostly sunny (10-20% sky coverage) by 1500.
...Thunderstorms imply strong gusty and erratic winds...
.TUESDAY...
Sky/weather.........Partly cloudy (40-50 percent) then becoming
mostly cloudy (70-80 percent). Slight chance of
rain showers late in the afternoon. Slight
chance of thunderstorms late in the afternoon.
CWR.................0 percent.
Chance of pcpn......30 percent.
Chance of thunder...20 percent.
Max temperature.....Around 64.
Min humidity........37 percent.
Wind (20 ft)........Light winds. Gusty and erratic winds expected
near thunderstorms late in the afternoon.
Ridgetop wind.......North around 10 mph until 1100, then southwest.
Mixing height.......2000 ft AGL until 1100, then 3500 ft AGL until
1200, then 7000 ft AGL until 1600, then 3500 ft
AGL.
Transport winds.....Northwest around 8 mph until 1000. Southwest 12
to 14 mph after 1500.
Smoke dispersal.....Poor until 1100, then fair. Increasing to good
until 1600, then poor.
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........45 55 50 35 35 40 40 45 55 80 75 65
Weather cov..... CHC SCH SCH
Weather type.... RW RW RW
Tstm cov........ SCH SCH SCH
CWR.............0 0 0 0 0 0 0 0 0 0 0 0
Chc of pcpn (%).0 0 0 0 0 0 10 10 10 30 10 20
Chc of thdr (%).0 0 0 0 0 0 10 10 10 20 10 20
Temp............37 34 38 46 57 61 62 64 62 60 60 59
RH..............79 79 77 62 48 41 37 36 39 45 46 49
20 FT wind dir..N N N N NW W W SW SW SW S SW
20 FT wind spd..3 3 3 3 3 4 5 6 6 6 6 5
20 FT wind gust.6 6 6 7 7 10 10 12 14 14 13 11
Ridge wind dir..N N N N NW W W SW SW SW S SW
Ridge wind spd..10 10 10 10 10 10 10 10 15 10 10 10
Mix hgt (kft)...0.5 0.5 0.5 1.0 2.0 3.5 5.5 6.5 7.0 5.5 3.5 3.0
Transp wind dir.N NW NW NW W W W SW SW SW S W
Transp wind spd.8 8 8 8 9 12 15 15 14 13 12 14
SDspl kt-ft/10004 4 4 6 15 35 70 82 83 60 33 38
.TUESDAY NIGHT...
Sky/weather.........Mostly cloudy (70-80 percent) then becoming
partly cloudy (45-55 percent) then becoming
mostly cloudy (50-60 percent). Rain showers
likely and slight chance of thunderstorms in
the evening.
CWR.................10 percent.
Chance of pcpn......60 percent.
Chance of thunder...23 percent.
Min temperature.....Around 34.
Max humidity........96 percent.
Wind (20 ft)........Light winds. Gusts up to 14 mph. Gusty and
erratic winds expected near thunderstorms in
the evening.
Ridgetop wind.......West 10 to 15 mph.
Mixing height.......500 ft AGL.
Transport winds.....Southwest 9 to 12 mph until 2000, then west 9
to 13 mph.
Smoke dispersal.....Poor.
TIME (MDT) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........90 95 90 90 85 80 60 60 55 45 50 55
Weather cov.....CHC LKY SCH CHC CHC SCH
Weather type....RW RW RW RW RW RW
Tstm cov........SCH SCH SCH SCH SCH SCH
CWR.............10 10 10 10 10 10 0 0 0 0 0 0
Chc of pcpn (%).50 60 20 30 40 10 10 10 10 0 10 0
Chc of thdr (%).20 20 20 10 10 10 10 10 10 0 0 0
Temp............56 55 51 48 45 42 41 40 39 39 37 36
RH..............55 58 65 71 78 84 87 92 95 95 96 96
20 FT wind dir..SW SW W W NW W W NW NW W NW NW
20 FT wind spd..5 4 4 5 5 6 6 6 6 6 6 6
20 FT wind gust.11 10 8 10 10 11 11 11 11 11 10 10
Ridge wind dir..SW SW W W NW W W NW NW W NW NW
Ridge wind spd..10 10 10 10 10 10 10 15 10 10 10 10
Mix hgt (kft)...2.0 1.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Transp wind dir.SW W W W W W W W W W W NW
Transp wind spd.12 9 9 10 10 12 12 13 12 12 12 12
SDspl kt-ft/100019 12 6 5 5 6 6 6 6 6 6 7
.WEDNESDAY...
Sky/weather.........Mostly sunny (40-50 percent).
CWR.................0 percent.
Chance of pcpn......0 percent.
Chance of thunder...1 percent.
Max temperature.....Around 64.
Min humidity........38 percent.
Wind (20 ft)........Light winds until 1100, then west around 7 mph
until 1700, then light. Gusts up to 20 mph.
Ridgetop wind.......West 10 to 15 mph.
Mixing height.......2000 ft AGL until 1000. 6500 ft AGL after 1300.
Transport winds.....West 12 to 15 mph.
Smoke dispersal.....Poor until 0800. Fair after 0900 increasing
to good after 1500.
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........40 65 50 35 30 25 20 20 20 20 20 25
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............36 35 38 44 49 55 59 60 60 60 61 62
RH..............96 99 95 85 73 60 50 45 44 43 40 38
20 FT wind dir..W W W W W W W W W W W W
20 FT wind spd..6 6 6 6 6 7 7 7 7 7 7 6
20 FT wind gust.10 11 12 13 14 14 14 16 16 16 16 14
Ridge wind dir..W W W W W W W W W W W W
Ridge wind spd..10 10 10 15 15 15 15 15 15 15 15 15
Mix hgt (kft)...0.5 0.5 1.5 2.0 3.0 3.5 4.5 5.0 5.5 6.5 6.0 5.5
Transp wind dir.W W W W W NW NW NW W W W W
Transp wind spd.12 12 14 15 15 14 14 14 14 14 14 13
SDspl kt-ft/10006 6 16 27 37 44 53 61 68 76 70 59
.FORECAST DAYS 3 THROUGH 5...
.THURSDAY...
Mostly clear. Lows in the mid 30s. Highs in the upper 60s.
Southwest winds 10-20 mph.
.FRIDAY...
Mostly clear. Lows in the upper 30s. Highs in the upper 60s.
West-southwest winds 15-30 mph.
.SATURDAY...
Partly cloudy. Slight chance of showers. Lows in the upper 30s.
Highs in the mid 60s. West-southwest winds 15-30 mph.
$$
Forecaster...LaVoie
Requested by...Tim Sherwin
Type of request...WILDFIRE
.TAG 2621796.8/RIW
.DELDT 09/21/26
.FormatterVersion 2.0.0
.EMAIL brandon.bonenberger@usda.gov,timothy.sherwin@usda.gov