textproduct: Western and Central Wyoming

KEY MESSAGES

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

- Somewhat drier air moves in Sunday, bringing 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.

UPDATE

Issued at 1130 AM MDT Sat Aug 15 2026

Early day showers and thunderstorms become more widespread this afternoon. Best chances still look to be across the northern half of the area, with widespread 20 to 60 percent chances. Locally moderate to heavy rainfall is possible with precipitable water values 0.75 to 1 inch for much of the area. Showers linger through this evening, with most done by midnight. Current satellite shows the drier air to the southwest making its way here, which will decrease rain chances Sunday.

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 /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1027 AM MDT Sat Aug 15 2026

VFR conditions are expected across nearly all terminals throughout much of the TAF period. Low clouds have lingered across KJAC this morning but gradual improvement is expected over the next hour or so after the start of the TAF period. Otherwise, monsoonal moisture is expected to persist across the region today. This influx of moisture will help fuel scattered showers and thunderstorms through the afternoon and evening Saturday. Showers and thunderstorms have already begun to develop across portions of western WY. Convection will continue to spread east through around 00Z Sunday with nearly all terminals having a 10-40% chance for a brief shower or thunderstorm. MVFR to IFR conditions cannot be ruled out at times especially if storms move directly overhead any terminals. Gusty winds may occur nearby developing storms with gusts of 30 knots or more possible. Conditions should improve after 00Z Sunday for nearly all terminals with KWRL and KCPR possibly seeing showers or storms linger to about 04Z. Conditions are expected to remain dry through the overnight into the morning hours on Sunday. Winds are forecast to remain light through this time period with speeds of 5 to 10 knots.

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.