textproduct: Western and Central Wyoming

KEY MESSAGES

- Patchy fog will be possible over portions of Natrona and Sweetwater County this morning, as well as any location that received precipitation Thursday. Any fog that does develop is expected to lift by 9 AM.

- Isolated virga showers will be possible over western portions again this afternoon, possibly crossing over into the central basins. 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). Late afternoon showers are possible (10-30% chance) Sunday and Monday afternoons, mainly across western Wyoming.

- The next chance for widespread precipitation looks to be Tuesday, with western portions having the highest chances.

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 /06Z TAFS THROUGH 06Z SATURDAY/

Issued at 950 PM MDT Thu May 21 2026

Winds have decreased across the region for most locations, and most snow showers have also begun to dissipate. KCPR and portions of central Wyoming are the exception, where light snow continues to fall as today's weather system slowly exits to the east. Expect snow to end at KCPR during the early AM hours.

The next aviation weather concern is a few hours of fog on Friday morning, due to Thursday's precipitation and clearing skies. Confidence is not high (roughly 20%) on fog for most locations, but there are hints in high-resolution forecast models, and the overall pattern is supportive. So if your location received precipitation over the past 24 hours, its likely wise to plan for the possibility of early morning visibility restrictions.

After lower atmospheric mixing begins shortly after sunrise (around 22/1400Z), fog should quickly dissipate, followed by a relatively benign aviation weather day on Friday with light winds and VFR conditions.

RIW WATCHES/WARNINGS/ADVISORIES

None.