textproduct: Western and Central Wyoming

KEY MESSAGES

- Partly cloudy to mostly sunny skies are expected for the rest of the day across the state. Cool northwest flow is keeping afternoon high temperatures about 5-10 degrees below normal.

- Very isolated virga showers are possible over the mountains this afternoon, possibly crossing over into the Upper Green River Basin, western Bighorn Basin, western Wind River Basin, and the Buffalo area. Wind gusts up to 40 mph will be possible from the associated outflows.

- There is high confidence that temperatures will warm into the 70s and 80s Saturday through Monday (Memorial Day). Afternoon showers are possible (10-30% chance) across northern WY on Saturday, across southwest and southern WY on Sunday, and across western WY from Uinta County to Park County on Monday.

- The next chance for widespread precipitation across western and central WY looks to be Tuesday, with breezy and unsettled weather expected for the rest of the week.

UPDATE

Issued at 100 PM MDT Fri May 22 2026

In the post-storm cool northwest flow environment, conditions are some low-level cumulus clouds with a bit of cirrus flowing over from the west. Recent snowfall in the lower elevations is melting today as temperatures climb to the 50s and low 60s (5-10 degrees below normal). Models are suggesting some very isolated showers over the mountains this afternoon, and possibly moving into the eastern foothills of the ranges. Some storms could produce outflow winds around 40 mph. However, the 18Z KRIW sounding shows a fairly strong cap around 700 mb which should inhibit most convective activity. A weak shortwave trough in the the mid-level northwest flow from western MT could weakly destabilize the current profile across northern WY to produce isolated showers over the northern WY mountains this evening. Isolated showers are then possible during the overnight hours as well as the trough moves into SD Saturday morning.

More westerly flow develops on Saturday, with moister conditions across northern WY, and drier breezy/gusty conditions across southern WY. The Bighorns are the most likely locations for isolated showers Saturday afternoon. Afternoon high temps will climb into the 70s (3-5 degrees above normal) with mid 40s to upper 60s in the mountains. The westerly flow then brings increasing temperatures on Sunday with a weak shortwave trough also increasing clouds across western and southern WY. Isolated showers are possible from SW into southern WY Sunday afternoon. Overall, a very nice Memorial Day weekend across western and central WY, though pay attention to thunderstorm chances across western WY Monday afternoon and evening, with increasing gusty south winds across the state.

DISCUSSION

Issued at 1250 AM MDT Fri May 22 2026

Much of the forecast area received a nice beneficial rain Thursday, with amounts ranging between 0.10" and 0.40". Locally higher amounts of 0.50" to 0.60" were also measured at the Casper Airport, Boulder, Byron and Powell.

Skies continue to clear early this morning, with circulation around the upper low over Converse County prominently visible on satellite imagery. Light precipitation will end over Natrona County in the next couple of hours as the storm continues its east-northeast trajectory. Low clouds/fog will remain in place here before lifting out by 15Z this morning. Similar conditions are expected to develop across Sweetwater County, with any impacts of fog over I-80 being somewhat isolated and patchy. Temperatures rebound today, rising 5 to 15 degrees warmer than Thursday, into the upper 50s and 60s. Isolated virga showers will be possible over the western mountains after 20Z, with this activity being similar to Wednesday forming over western portions of the CWA and tracking eastward through the afternoon. Some of these will cross into the central basins and around sunset. Wind gusts up to 40 mph will be possible from the associated outflows from these showers, due to dewpoints dropping into the upper teens and 20s this afternoon.

Saturday continues to look to be a nice start to the holiday weekend, with highs in the 70s, mostly clear skies and generally light winds. Temperatures in the 70s and 80s will be in place Sunday and Monday, with elevated to critical fire weather conditions possible for portions of Johnson County and the Bighorn and Wind River Basins Monday afternoon. Isolated, late afternoon showers and thunderstorms will be possible Sunday and Monday as well. Winds will turn more southerly by Tuesday, as a storm system drops southward over the PACNW. Moisture will increase over the Cowboy State as well, with Gulf moisture making its way into areas east of the Divide. This looks to be the next day for widespread precipitation chances and possibly strong thunderstorms. Additional showers and thunderstorms will be possible across the Cowboy State Wednesday and Thursday, as the storm develops into a cutoff low and settles over NV/ID.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 447 PM MDT Fri May 22 2026

VFR conditions through the period. A few lingering virga showers will dissipate within the first couple of hours of the period. Gusty wind remains possible with these showers until they dissipate this evening. Light winds prevail overnight, with periods of high clouds. Winds increase late Saturday morning, with gusts generally 15 to 25 knots through the afternoon. A few light showers, or virga showers, are possible during the afternoon as well. These will mainly be confined to higher terrain and for northern Wyoming, but could spread into the nearby basins; have included VCSH for TAFs to account for this hazard.

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.