textproduct: Western and Central Wyoming

KEY MESSAGES

- Breezy north to northwest winds will persist through the day today, but gusts will be notably less than those on Saturday, with 15 to 25 mph gusts in the forecast for most locations. Gusts closer to 35 mph are expected in the Upper Green River Basin and Sweetwater County.

- Temperatures on Sunday will be about 15 to 40 degrees colder than those experienced Saturday.

- Snow showers are expected off the east slopes of the Bighorns this afternoon, impacting the I-25 corridor in the southern half of Johnson County. Reduced visibilities will be the main impact with minor snowfall accumulations.

- Widespread windy conditions return Tuesday, with high winds possible (30-50%) over the Cody Foothills and Wind River Basin. - Confidence is high (90%) for well above average temperatures from Tuesday into next weekend, with record-breaking heat expected from Wednesday into the weekend. Some locations east of the Divide could have the earliest 80 degree day on record.

UPDATE

Issued at 1226 PM MDT Sun Mar 15 2026

The current temperature at the office is 22 degrees, which is the normal low temperature for today. Visible satellite imagery shows the freshly fallen snow already starting to erode as late winter/early spring higher angle sunshine warms things up. For the most part, skies will remain mostly clear, allowing for some more melting through sunset. Enough melting may occur in the areas that received the most snowfall that some freezing fog formation is possible, especially around Lander and along I-25. Signal is not overly strong, but added moisture in the atmosphere does not rule it out. Overnight temperatures still on track to fall back into the single digits and teens east of the divide, and in the 20s to the southwest.

Longer term outlook for the week still looks like an unprecedented warm spell, with highs pushing 30 degrees above normal...

DISCUSSION

Issued at 122 AM MDT Sun Mar 15 2026

Snow continues to end from north to south early this morning, with most of the snow ending over central portions between midnight and 1AM (07Z). On average, temperatures rapidly dropped 20 degrees in 30 minutes Saturday evening behind the front, with the Riverton Airport dropping 11 degrees in 5 min. Temperatures will continue to slowly drop through the rest of the night, with readings in the single digits and teens by sunrise. It will be a raw day today across the Cowboy State, with readings 15 to 40 degrees colder from Saturday, leaving daytime highs in the 20s and 30s. The southern end of Flaming Gorge looks to be the warmest location, with a high near 40F. Winds will also continue to decrease through the rest of the morning, before increasing again over the western half of the CWA by 18Z. North to northwest winds will occur across the forecast area today, with gusts of 25 to 30 mph in the aforementioned area. Snow showers will develop off the east slopes of the Bighorns this afternoon as a result of these winds and impact the I-25 corridor in the southern half of Johnson County. This would include Kaycee and the I-25 Divide. Snowfall amounts will be minor, less than 1 inch, but visibilities could be reduced so caution is advised for any travelers this afternoon. Winds will decrease again this evening, but will increase back toward 25-30 mph over Sweetwater County by the predawn hours Monday morning. Snow showers will redevelop over northwestern portions of the CWA after 06Z Monday, as a fresh round of Pacific moisture rounds the ridge and over this area within a northwest flow pattern. This snow will continue through the day Monday, with minor accumulations. The western slopes of the Absarokas along the eastern edge of YNP will have the highest amounts of 2-4 inches. The cold conditions today will be temporary though (it is March after all), as a strong ridge builds over the West Coast. Monday morning will be cold again, with readings in the single digits to middle 20s. Temperatures will quickly rise through late morning into the early afternoon, with some locations having about a 40 degree swing from the morning low to the afternoon high. Gusty west to northwest winds will aid in the warmer temperatures, with gusts of 25 to 40 mph occurring over the Upper Green River Basin and the Wind Corridor (Rock Springs to Casper), as well as the Upper Wind River Basin.

The story from Tuesday onward will be the above normal temperatures as the high center from the ridge begins to move over southern CA. This high center will slowly track eastward over the Desert Southwest and the Four Corners through Saturday. The high center will start as high as 591dm (at 500mb), strengthening to 594-597dm by Thursday over the Desert Southwest. This is very anomalous for this time of year and can expect highs in the 60s and 70s by Tuesday. The gradient will tighten again Tuesday, with northwest flow aloft remaining in place. 700mb winds will increase to 30-40kt for much of the CWA. High winds are looking likely again in the Cody Foothills and the Wind River Basin, as models prog 700mb winds of 50-60kt off the east slopes the Absarokas and the Upper Wind River Basin. Tuesday was already looking to be a windy day across the CWA again, but High Wind Warnings look likely now ("Just when I thought I was out, they pull me back in").

Gusty winds look to continue Wednesday as the gradient remains tight, however this will change by Thursday as the influence from the PFJ gets shunted northward and the high center moves over the Desert Southwest. Several locations could reach 80 degrees Thursday and Friday, which would be the earliest 80 degree day on record by about 4 weeks. Here are some dates for reference: Casper - April 11; Lander - April 11; Worland - March 28; Riverton - April 23. Lastly, river levels may begin to rise by next Friday as a result of these anomalously warm temperatures, but soil conditions remain very dry and are expected to absorb any extra water.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1118 AM MDT Sun Mar 15 2026

North to northwest winds will be in place for most locations in the wake of yesterday's cold front. The unstable northwest flow aloft may produce some spotty snow showers coming off the mountains, so an occasional light snow is possible for near mountain locations, like KJAC, but it should mainly be dry. Snow chances increase tonight over the western mountains, with KJAC possibly seeing snow as early as about 07z/Mon, but peak chances (30%-40%) occur near the end of the period.

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.