textproduct: Western and Central Wyoming

KEY MESSAGES

- A weather system moving across the area will bring areas of showers and isolated thunderstorms today into this evening.

- Locally heavy rain will be possible with any shower or thunderstorm today, although the chance of flooding is low.

- Largely tranquil weather is then expected for most of remainder of the week, with only a couple of chances of light showers. Temperatures will continue to average near to above normal.

DISCUSSION

Issued at 129 AM MDT Mon Sep 28 2026

We are currently getting some much needed moisture across the area with some areas of showers and isolated thunderstorms. This is courtesy of a shortwave moving toward the area. It is getting an a assist from a 95 knot jet streak that is approaching southwestern Wyoming and will cross southern Wyoming this afternoon and evening, putting much of the area in the left front quadrant of it to enhance lift somewhat. As a result, almost all areas will have a chance of showers today. There will also be some embedded thunderstorms. However, with cloud cover around the area, surface instability may be limited. The main threat from any storm would be locally heavy rain, with precipitable water values generally running anywhere from 125 to 150 percent of normal. A mitigating factor will be that there will be steering flow, so any storms will have decent motion and not be able to anchor. With more cloud cover, temperatures will also run around 5 to 10 degrees cooler than Monday. Coverage of showers and thunderstorms should decrease after sunset, ending generally from northwest to southeast, although with the jet still in the area overnight, isolated showers and thunderstorms may linger south of a Casper to Rock Springs through the night.

And, we could see some higher elevations snow from this. Any accumulation would likely be restricted to above 11000 feet though. The highest elevations of the Wind River Range, like the Gannett Peak, have a 1 in 2 chance of seeing 3 inches of new snow. There should be little or no impact to travel though.

We should then enter a quieter period of weather as ridging builds into the area from the west, pushing drier air into western and central Wyoming. There may be just enough leftover moisture for some isolated showers in southern Wyoming, but this looks like the exception rather than the rule. Following that, things look mainly dry through the week and even into the weekend. A large majority of the guidance keeps the moisture associated with an upper level low and the remnants of Hurricane Polo to the south of the area through the forecast period.A weak cold front will move into northern and central Wyoming Wednesday night. This front is moisture starved though so it will likely only bring some clouds and somewhat cooler temperatures and a gusty breeze, especially to northern Wyoming. Another front may move through Friday night or Saturday, but again it has little moisture to work with so any showers would be isolated with the only impacts somewhat cooler temperatures and some gusty breezes. Temperatures will generally average above normal, with Thursday and Sunday looking like the coolest days behind the front. But even here, temperatures will only fall back to near normal levels. So, once we get past the next 24 to 36 hours, things look fairly uneventful as we head into October.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 434 AM MDT Mon Sep 28 2026

A weather system will bring areas of showers and isolated thunderstorms through much of the TAF period, before ending from northwest to southeast after sunset tonight, although a few showers may linger in vicinity of KRKS and KCPR much of the night. Largely VFR conditions are expected a majority of the time, but brief MVFR or even IFR conditions may occur in the heavier showers and thunderstorms. Confidence timing of the rounds of showers and thunderstorms, especially after 18Z today, remains low as model agreement remains low. Wind should remain under 11 knots for the most part, although gusts to 30 to 35 knots will be possible in vicinity of any shower or thunderstorm. Occasional mountain obscurations will be around through the day and into the night. Patchy fog may develop after 07Z tonight, although not enough confidence to include in the forecast at this time.

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.