textproduct: Western and Central Wyoming

KEY MESSAGES

- Another day of showers and thunderstorms today, with most activity across northern Wyoming today. Local heavy rain remains possible.

- Somewhat drier air moves in on Sunday and brings warmer temperatures and fewer showers and storms.

- Monsoonal moisture moves in and out next week, with Tuesday and Wednesday looking like the most active days, with the least coverage on Thursday and Friday.

DISCUSSION

Issued at 132 AM MDT Sat Aug 15 2026

The weather has been rather active over the past couple of days, with some reports of flooding with the monsoonal moisture over the area. It also brought some needed rain to portions of the area. And this looks to continue, although there will be some fluctuations over the next few days. As for now, we still have some showers and embedded thunder out there right now, although they are slowly weakening. A few showers may hang around until sunrise though.

We will still be under the monsoonal moisture today. However, the core of it will shift a bit more to the north and east as some drier air tries to punch in from the southwest. Precipitable water values on average are around 15 to 20 percent lower than on Friday, with a northeast to southwest gradient from most moist to the least (from around a 1 in 6 chance in southern Wyoming to as much as 1 out of 2 in the northern mountains. So, the best chance of showers and storms will be across northern Wyoming where we still have a marginal risk of excessive rainfall today. There is still some steering flow so this should cut the threat of flooding somewhat but it is still possible in local areas. Temperatures will be similar to yesterday, evening around 5 degrees below seasonal averages. Most guidance is also showing an earlier show, with most convection over by sunset and almost all showers and storms over by midnight.

Drier air should then push further eastward on Sunday, dropping the chance of showers and storms even more. There will still be a few around, but with precipitable water values returning close to seasonal normals and dew points generally 10 to 15 degrees lower than on Saturday, most locations should be rain free. There will also be more sunshine along with somewhat warmer temperatures aloft. This will allow for warmer temperatures, probably returning closer to seasonal normals. At this point, things look largely quiet after sunset on Sunday night.

Things may turn more active again on Monday, especially later and into the night. Guidance shows precipitable water values climbing back to around 130 to 150 percent of normal. At the same time,a subtle shortwave will be moving through the area. As a result, the chance of showers and storms increases again this day, and possibly lasting into the nighttime hours as well. This more active pattern looks to last into Tuesday and possible Wednesday as well, especially across northern Wyoming where another shortwave may be passing. Temperatures through this period look to be near to possibly slightly below normal.

Following Wednesday, most guidance shows ridging over the desert southwest building back northward into the central and northern Rockies for the end of the work week. As a result, temperatures should begin a warming trend starting on Thursday and especially Friday and into next weekend, when above normal temperatures again look likely for most of the area, with 90s across many of the lower elevations East of the Divide. As for convection, Thursday and Friday look largely dry at this point, with only isolated showers over the higher elevations. Some monsoonal moisture may return for the weekend, but this far out it uncertain is rather high. So, the story for the next seven days will be the monsoon, and it's ebbs and flows over the period.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 401 AM MDT Sat Aug 15 2026

Monsoonal moisture will remain over the area with a scattering of showers and thunderstorms, mainly in the afternoon and evening between 19Z Saturday and 02Z Sunday, although a few showers will be around in the morning as well (around a 15 percent chance). All TAF sites will have a chance of showers and thunderstorms and PROB30 groups were kept at most TAF sites. The chance in vicinity of KRKS (20 percent) is too low to include in the TAFs at this time.

With the rain that fell in vicinity of KJAC on Friday, patchy fog will be around until around 15Z from time to time so we included a TEMPO group there. Wind should be mainly under 10 knots except in and around any shower or thunderstorm where gusts to 30 knots are possible.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

None.