textproduct: Western and Central Wyoming

KEY MESSAGES

- The next weather system brings valley/basin rain and mountain snow Monday and Tuesday, with the highest totals most favored on and around the Wind River Mountains. - Colder temperatures this week, with Freeze Watches for lower elevations east of the Continental Divide Tuesday night and Wednesday morning when lows drop below 32 degrees.

- Another weather system skirts across northern and central Wyoming Thursday into Friday with additional precipitation chances (20-40%).

DISCUSSION

Issued at 200 AM MDT Mon May 4 2026

IR currently depicts a closed low to the southwest near California as WV shows the PFJ dipping further south out of Canada and Montana into northeastern portions of the state. Current model trends continue the southward progression of the jet with a jet max of 120kts pushing into the next shortwave expanding across much of the CWA for Monday. This will drop a cold front through the area in the morning hours that will see cooler temperatures from Sunday around 10 to 15 degrees for afternoon highs. Otherwise, scattered rain showers expected with the front that will expand into the evening and overnight hours as the shortwave progressively moves across the CWA. Minimal impacts expected with any snow accumulations constrained to higher elevations even above mountain passes.

Tuesday will see a more widespread mountain snow/valley rain effect as the aforementioned low to the southwest will embed into the positively tilted trough extending from the Dakotas. More ample divergence aloft expected, especially across the southern half of the CWA where QPF amounts could push over a quarter inch (60-70%) in some spots along the I-80 corridor of Sweetwater County and points south to the Colorado border. Otherwise, snowfall rates for the higher elevations will be greatest during the afternoon and into the evening hours. Minimal impacts expected to mountain passes (South Pass the only one to push advisory level amounts). However, with the warm temperatures ahead of this system and more of a longer duration time frame, any issuances were held off at this time for Tuesday and Tuesday night. However, a reinforcement of cooler air expected into Wednesday morning seeing a widespread below freezing event for basins east of the Divide. As such, freeze watches continue with this being the coldest morning of the week ahead.

Additional precipitation chances with minimal impacts expected Thursday and Thursday night as the main trough exits to the east. This will give way to upper level ridging to build back in Friday and into the weekend with dry conditions and a warming trend expected. Northwest flow aloft extends through into early next week with a minor shortwave pushing to the northeast Saturday afternoon that might see some sporadic showers for the Bighorns and northeastern counties, but much of the activity will remain northeast.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1114 AM MDT Mon May 4 2026

A complex weather pattern through the next 24 hours (and beyond). Today, afternoon heating combined with an approaching front will help to create showers and thunderstorms across the area, generally through about 02z. Locations generally have a 15 to 40 percent chance of seeing a shower or storm, with the main hazard being gusty outflow winds up to 40 knots. Chances don't completely end this evening, however, as the front begins to move through. Precipitation mode should chance from a showery coverage to more widespread precipitation, and will change from rain to snow or rain/snow mix overnight for most locations. Between the hours of 00z and 12z is challenging due to the complex transition of afternoon showers ending, widespread precipitation starting, the front moving through, and when/if a transition from rain to any snow occurs. For most locations, precipitation continues through the end of the period once it begins this evening or overnight. KCOD, KJAC, and KWRL would be the least favored for this continuous precipitation.

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

Freeze Watch from late Tuesday night through Wednesday morning for WYZ003>006-010-011-017-018-020.