textproduct: Cheyenne

KEY MESSAGES

- A potent Pacific storm system will remain north of the region today, with somewhat cooler temperatures and evening showers and thunderstorms possible north of Interstate 80. A few of these thunderstorms may contain hail and gusty winds.

- Elevated fire weather conditions continue Sunday, with critical conditions possible Monday. Elevated fire weather conditions will continue for much of the week ahead.

SHORT TERM /THROUGH TUESDAY/

Issued at 305 AM MDT Sun Jun 28 2026

Current observations and IR Satellite loop across the northern Rockys show a potent late-season Pacific storm system producing high elevation snowfall for Montana, Idaho, and northwest Wyoming. This storm will continue to plague the region over the next few days. Further south in our area, a slow cooling trend is expected today and Monday (likely into Tuesday also) as another reinforcing shot of cooler air moves across the area late Tonight and Monday.

For Sunday, models continue to show the drier airmass moving into western Nebraska with dewpoints briefly lowering into the upper 30s to mid 40s by this afternoon. Although a little cooler compared to Saturday, high temperatures in the 80s to around 90 are still expected over the eastern high plains...warmest below 5000 feet. Mostly dry today with little to no precipitation through late in the afternoon. Once the reinforcing shot of cooler air begins to move east later this evening, a surface low is expected to form across the plains and rapidly move northeast along the main cold front. Low level winds are forecast to shift back into the south or southeast across the eastern plains with moisture advection and return flow off the Great Plains. Models continue to indicate a conditional risk for thunderstorms in the late evening hours and overnight as a 100kt jet max moves into the eastern part of the state. High res guidance and CAMs show a few isolated thunderstorms getting going near Chadron, Lusk, and Alliance. Kept the highest POP in this area with very little activity as far south as I-80. Synoptic models are not quite as aggressive as yesterday, but the ECMWF still shows a good chance of scattered showers and widely scattered thunder for east central Wyoming and the northern/central Nebraska panhandle. A few strong to marginally severe thunderstorms are possible due to pretty good forcing for late June. Models soundings show between 1000 to 1500 j/kg of elevated MUCAPE in the Chadron area between 9 PM tonight and 3 AM early Monday, so will have to watch this area for strong gusty winds and some marginally severe hail. Again, overall risk if pretty low at this time with SPC showing a Marginal Risk of severe weather clipping Sioux and Dawes counties later today and tonight.

For Monday, models show the base of the potent upper level trough axis lifting northeast across the area. Can't rule out some light snow for the Sierra Madre and Snowy Ranges with snowlevels around 9500 feet and 700mb temperatures briefing falling to -1c. As this trough axis moves across central and east central Wyoming, strong 700mb winds are expected with speeds around 50 to 55 knots for a few hours. Models also show a pretty strong surface pressure gradient for late June in the late morning and early afternoon. In-house wind guidance has picked up on this potential with probabilities of 30 to 45 percent chance for High Wind criteria, although it is only brief and doesn't last any more than a few hours. Kept wind gusts of 45 to as high as 60 MPH...mostly across Albany, Converse, and Platte counties, with the Arlington/Elk Mountain area another secondary concern. Fire weather concerns will continue to be tricky on Monday with dry air and a cooler airmass playing a balancing act. Will continue to monitor model trends as we head into Monday for any potential High Wind and/or Fire Weather headlines. As of right now, won't issue anything due to lower than average confidence. Pretty chilly Monday night into Tuesday morning with low temperatures likely in the 30s for Carbon and Albany counties.

LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/

Issued at 303 PM MDT Sat Jun 27 2026

The upper level low will eject to the east by Tuesday, reducing the gradients and thus the wind speeds across our area Tuesday onwards. Expect a gradual warming trend through the week ahead as the broad ridge dominating the eastern two thirds of the country expands westward. Tuesday and Wednesday will probably see temperatures fairly close to seasonable averages, increasing to above average by Thursday and Friday. Winds look marginal for Red Flag Warnings during this period, but it would not be surprising to see wind speeds increase as we get closer. Fire weather concerns will be at least elevated for much of the week. Most afternoons and evenings during the week will bring potential for a few isolated showers and thunderstorms, but it is difficult to determine which days will be most noteworthy, and what the storm hazards might be.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1133 AM MDT Sun Jun 28 2026

On Satellite we may have a cumulus fied starting to develop which may give KCYS a brief shower but its more for the skies to become scattered to broken this afternoon. This evening the trough that is slowly pushing through may also give KBFF a brief shower but its more likely to be like KCYS and have scattered to broken skies. The models have a weak thunderstorm dropping down from South Dakota to give KCDR thunderstorm chances in the late evening otherwise every other terminal looks dry. The winds look to pick up tonight into tomorrow as that trough moves into the Northern Plains. Gusts between 35-40 kts will be possible tomorrow afternoon.

CYS WATCHES/WARNINGS/ADVISORIES

WY...None. NE...None.