Spot Forecast
Issued by NWS Riverton, WY
Issued by NWS Riverton, WY
639
FNUS75 KRIW 192321
FWSRIW
Spot Forecast for Telephone...USFS SHF
National Weather Service Riverton WY
521 PM MDT Sat Sep 19 2026
Forecast is based on forecast start time of 0600 MDT on September 20.
If conditions become unrepresentative, contact the National Weather
Service
.DISCUSSION...
Low clouds/fog will be in place through at least 0900, with clouds
lifting/scattering out by 1000. Showers (and possibly a
thunderstorm) will become possible after 1300, with the greatest
confidence of 20 to 40% occurring between 1500 and 2000). Brief
heavy rain will remain possible as the air will remain very moist
Sunday, but confidence is low. Low clouds will return with the
chances for rain and linger after 2000. These clouds will
gradually scatter out through the overnight hours Sunday night,
with partly cloudy skies expected by sunrise Monday morning.
Freezing temperatures will be possible during this time as well.
Dry conditions will return Monday, with winds turning
southwesterly 10-15 mph after 1300.
...Thunderstorms imply strong gusty and erratic winds...
.SUNDAY...
Sky/weather.........Mostly cloudy (60-70 percent). Patchy fog early
in the morning. Slight chance of rain showers
early in the morning. Slight chance of
thunderstorms in the afternoon. Chance of rain
showers late in the afternoon.
CWR.................0 percent increasing to 11 percent in the
afternoon.
Chance of pcpn......50 percent.
Chance of thunder...16 percent.
Max temperature.....Around 59.
Min humidity........53 percent.
Wind (20 ft)........Light winds. Gusty and erratic winds expected
near thunderstorms in the afternoon.
Ridgetop wind.......West around 10 mph until 1600, then south.
Mixing height.......2000 ft AGL until 1100, then 4000 ft AGL.
Transport winds.....Northwest 8 to 12 mph.
Smoke dispersal.....Poor until 1000 increasing to fair after
1400.
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........75 75 55 45 60 60 75 70 65 70 75 85
Weather cov.....SCH PTY PTY SCH CHC CHC CHC CHC
Weather type....RNF FOG FOG RW RW RW RW RW
Tstm cov........ SCH SCH SCH SCH SCH
CWR.............0 0 0 0 0 0 10 10 10 10 10 10
Chc of pcpn (%).20 0 10 0 0 0 10 10 30 50 40 50
Chc of thdr (%).0 0 0 0 0 0 10 10 10 20 20 20
Temp............34 33 34 42 51 53 55 58 56 54 55 55
RH..............100 100 100 85 70 65 57 52 53 58 55 53
20 FT wind dir..W W N NW W W W W W SW SE S
20 FT wind spd..3 3 3 3 3 4 4 5 6 6 6 5
20 FT wind gust.6 6 6 7 7 8 8 10 12 13 13 12
Ridge wind dir..W W N NW W W W W W SW SE S
Ridge wind spd..10 10 10 10 10 10 10 10 10 10 10 10
Mix hgt (kft)...0.5 0.5 0.5 1.5 2.0 3.0 4.0 4.0 4.0 4.0 3.5 3.5
Transp wind dir.NW NW NW NW NW NW NW W W W NW NW
Transp wind spd.8 8 8 8 8 9 9 10 12 12 12 10
SDspl kt-ft/10004 4 4 9 15 25 31 34 40 41 37 30
.SUNDAY NIGHT...
Sky/weather.........Mostly cloudy (75-85 percent) then becoming
partly cloudy (30-40 percent). Chance of rain
showers early in the evening. Slight chance of
thunderstorms early in the evening.
CWR.................2 percent.
Chance of pcpn......30 percent.
Chance of thunder...14 percent.
Min temperature.....Around 32.
Max humidity........100 percent.
Wind (20 ft)........Light winds. Gusty and erratic winds expected
near thunderstorms early in the evening.
Ridgetop wind.......South around 10 mph until 2000, then light
until 0500, then north around 10 mph.
Mixing height.......1500 ft AGL until 2000, then 500 ft AGL.
Transport winds.....West around 10 mph until 1900, then south 7 to
8 mph until 2200, then light until 0100, then
north 7 to 10 mph.
Smoke dispersal.....Poor.
TIME (MDT) 6PM 7PM 8PM 9PM 10P 11P MID 1AM 2AM 3AM 4AM 5AM
Sky (%).........90 90 80 80 80 85 80 95 85 65 65 35
Weather cov.....CHC CHC 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 (%).30 30 20 10 10 0 0 0 0 0 0 0
Chc of thdr (%).10 10 10 10 10 0 0 0 0 0 0 0
Temp............55 53 48 46 44 41 40 39 38 37 35 34
RH..............53 57 68 74 80 91 95 100 100 100 100 100
20 FT wind dir..S S S S S N N W N N N N
20 FT wind spd..5 3 2 2 1 0 0 1 1 2 2 3
20 FT wind gust.12 8 6 5 4 2 2 2 4 5 5 6
Ridge wind dir..S S S S S N S W N N N N
Ridge wind spd..10 10 5 5 5 5 5 5 5 5 5 10
Mix hgt (kft)...3.0 1.5 1.0 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5
Transp wind dir.W S S S SE SE SE N N N N N
Transp wind spd.10 8 7 7 6 5 6 7 8 8 9 10
SDspl kt-ft/100027 12 5 3 3 2 3 3 4 4 4 5
.MONDAY...
Sky/weather.........Mostly sunny (25-35 percent).
CWR.................0 percent.
Chance of pcpn......0 percent.
Chance of thunder...1 percent.
Max temperature.....Around 64.
Min humidity........41 percent.
Wind (20 ft)........Light winds until 1600, then southwest around 7
mph with gusts to around 16 mph.
Ridgetop wind.......North around 10 mph until 0900, then light
until 1200, then southwest 10 to 15 mph.
Mixing height.......2000 ft AGL until 1100. 5500 ft AGL after 1500.
Transport winds.....Northwest 8 to 9 mph until 1100, then southwest
8 to 14 mph.
Smoke dispersal.....Poor until 1000. Fair after 1400.
TIME (MDT) 6AM 7AM 8AM 9AM 10A 11A 12P 1PM 2PM 3PM 4PM 5PM
Sky (%).........25 45 30 15 15 10 10 15 20 25 25 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............34 32 36 42 49 55 59 60 60 60 62 63
RH..............100 100 93 81 69 57 48 44 43 43 41 40
20 FT wind dir..N N NW NW W W SW SW SW SW SW SW
20 FT wind spd..3 3 3 2 2 2 3 4 6 6 7 7
20 FT wind gust.6 6 6 6 6 6 6 10 12 14 16 16
Ridge wind dir..N N NW NW W W SW SW SW SW SW SW
Ridge wind spd..10 10 10 5 5 5 10 10 10 15 15 15
Mix hgt (kft)...0.5 0.5 1.0 1.0 2.0 3.5 4.5 4.5 5.0 5.5 5.0 4.0
Transp wind dir.N N NW NW NW W SW SW SW SW SW SW
Transp wind spd.9 9 9 8 8 8 8 9 12 13 14 14
SDspl kt-ft/10004 4 6 7 15 23 31 38 50 58 57 51
.FORECAST DAYS 3 THROUGH 5...
.TUESDAY...
Partly cloudy. Lows in the lower 30s. Highs in the upper 60s.
Southwest winds 10-20 mph.
.WEDNESDAY...
Mostly cloudy. Chance of showers and slight chance of
thunderstorms. Lows in the upper 30s. Highs in the mid 60s.
West-northwest winds 10-15 mph.
.THURSDAY...
Mostly clear. Lows in the mid 30s. Highs around 70. Southwest
winds 5-10 mph.
$$
Forecaster...LaVoie
Requested by...Tim Sherwin
Type of request...WILDFIRE
.TAG 2621796.6/RIW
.DELDT 09/19/26
.FormatterVersion 2.0.0
.EMAIL brandon.bonenberger@usda.gov,timothy.sherwin@usda.gov