textproduct: Cheyenne

KEY MESSAGES

- Another round of rain and high elevation snow is expected late Wednesday afternoon through Thursday morning.

- Accumulating snow is expected above 7000 ft this evening through Thursday morning. Snow levels may lower down to 5500 to 6000 feet briefly before precipitation ends later Thursday morning.

- A growing-season-ending freeze is expected Thursday night into Friday morning across the entire area.

- Drier and milder weather expected this weekend into early next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 400 PM MDT Wed Oct 14 2026

Most of our area is in the midst of another lull in the action as the slow moving, powerful upper level low rotates to our south. Dry air in the middle to upper atmosphere is apparent on GOES water vapor imagery moving over most of the area as a dry slot on the eastern flank of the storm system. This is not obvious looking up from the surface though, as persistent easterly upslope flow is keeping low clouds firmly locked in place everywhere along and east of the Laramie range. Low clouds are clearly apparent on GOES visible satellite imagery with the mid to upper level cloud cover gone. Precipitation rates have gone down to near zero without the moisture aloft, but portions of the area are still observing mist. The cloud cover is holding temperatures down for the entire area. Only around Chadron are temperatures exceeding 50 degrees, while everywhere else remains stuck in the 40s.

A dynamic period of weather is anticipated over the next 18 hours as the last phase of this storm system gets underway. The center of the upper level low is currently located near the Four Corners, but the primary band of precipitation is developing across central Wyoming. This feature is forced by positive theta-e advection and isentropic lift, which should eventually transition into the TROWAL. Model guidance is finally converging on a solution with this system, but there have been a few recent changes in the overall evolution. While this has removed several of the outlier models from previous runs and increased confidence, the official forecast has not changed significantly. The latest RAP guidance shows the upper level low struggling to fully separate from the northern branch trough this evening. This is expected to limit isentropic lift on the entire northeast flank of the system, which reduces the window for precipitation to just the narrow TROWAL on the back edge. Shower activity is still expected to increase this evening, but QPF expectations are more modest until the primary band of precipitation develops and moves through the area from northwest to southeast Thursday morning. While precipitation rates are still expected to be healthy underneath this band, it will be narrow and moving fairly rapidly, reducing overall QPF compared to some of the more aggressive model solutions yesterday. Current expectations are for 0.5 to 0.75" liquid precipitation in the core of the band from around Arlington towards Torrington and possibly Alliance. 0.25 to 0.5" of QPF are now the most likely scenario along the Douglas to Chadron corridor and along I-80 east of Cheyenne, though localized embedded convective cores will likely lead to locally higher amounts in a few areas. Precipitation will come to an abrupt end Thursday morning, around daybreak along a Rawlins to Chadron line, and then closer to noon around Sidney as a very dry airmass pushes in behind the northern branch shortwave sweeping through.

The cold air expectations for this system remain on track with previous forecasts. Snow levels will plummet overnight tonight as the coldest air moves in between about 3AM and 9AM. This is still expected to align with the timing of the heaviest precipitation rates moving across the area. Confidence remains high in accumulating snow about 7000 ft in elevation, including the city of Laramie. The Winter Weather Advisory has been expanded to include the Laramie Valley with between 2 and 4 inches of snow as the most likely scenario at this time. While this is somewhat on the low end for an advisory, it will be the first event of the season and likely come with a brief window of heavy snowfall rates aligned with the Thursday morning commute. The remaining Winter Weather Advisories remain on track. Between 6000 ft and 7000 ft, snow is expected to mix in with rain in the narrow coldest window Thursday morning. Between a dusting and an inch of snow can be expected in this elevation window, which includes Cheyenne. Temperatures will be highly marginal, and may not quite reach freezing even if areas receive some snow.

Expect a cold and blustery day across the area Thursday. While skies will clear, expect gusty north to northwest winds up to around 30 to 40 mph over much of the area with highs stuck in the 40s to low 50s. This will set up Thursday night for the coldest temperatures of the season. Recent model guidance has trended slower in the end of the gusty winds, meaning we may still be quite breezy into the overnight hours, especially early. This has moderated temperature expectations slightly, but the airmass should still be sufficiently cold to produce a widespread freeze, even if a shallow surface inversion never manages to develop. A Freeze Watch has been issued for the entire area excluding the mountains from midnight until 9AM Friday.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 400 PM MDT Wed Oct 14 2026

After coming off a hard freeze Thursday night, temperatures will gradually warm up Friday after melting off frost and potentially snow for some areas. As the Pacific storm exists towards the Great Lakes region, upper-level ridging will begin to build in behind it. The ridge will rapidly usher in warm air aloft, with 700 mb temperatures rising into the upper single digits. Despite the warm temperatures aloft, surface temperatures will take longer to rebound. Highs on Friday will be about 10 degrees below average, with temperatures generally in the 50s across the forecast area. Areas with snow cover could be cooler, namely the Laramie Valley, with highs in the 40s. Even though temperatures will be on the seasonably cool side, ample sunshine throughout the day will help cut through some of the chill.

As the upper-level ridge shifts eastward overnight on Friday, mid- level winds will become more westerly. The westerly winds will pose a possible concern for high winds in the typical southeast Wyoming wind prones of Arlington and Bordeaux during the day Saturday. MSLP gradients will steepen along and west of the Laramie Range. CAG to CPR 850 mb gradients also reach the 50 meter range, signaling the potential for gradient driven marginal high winds in the wind prones. 700 mb winds will reach about 40 kts, but subsidence is rather weak and will likely not play a huge role in the winds Saturday into Sunday morning. Wind gusts of at least 40 to 50 MPH will be likely during the day Saturday and into the overnight hours. Westerly winds will help play a role in the warm, above average temperatures on Saturday. Downsloping winds will aid 90th percentile 700 mb temperatures in achieving daytime highs in the 70s for areas east of the Laramie Range. To the west, highs around 60 degrees can be expected. Ample sunshine is once again expected for Saturday.

Above average temperatures will continue into the start of next week with highs in the 60s and 70s expected Sunday through Tuesday. Conditions during this time are also expected to remain dry, with mostly sunny skies expected each day. Cannot rule out a low-end chance of precipitation during the evening on Tuesday as a shortwave glances the CWA, however, models seem to have trended this drier.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1145 AM MDT Wed Oct 14 2026

A storm system will begin to move into the area today, bringing major aviation impacts to both southeast Wyoming and western Nebraska terminals. Although not much precipitation is expected during the afternoon today, the area will be socked in by clouds, with MVFR to IFR CIGs expected for all terminals. A few terminals may briefly see CIGs lift to VFR, but the window for this will be short. Precipitation will begin to move in early this evening to southeast Wyoming terminals. Precipitation will start out as rain, but transition to snow overnight when winds turn northerly. Snow will likely significantly reduce visibility. IFR visibility is anticipated once snow begins. Rain is not expected to transition to snow at western Nebraska terminals, but starting this evening, precipitation will continue throughout the night. Impacts to visibility are still possible in moderate rain.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Freeze Watch from late Thursday night through Friday morning for WYZ101-102-104>111-113-115>119. Winter Weather Advisory from 6 PM this evening to noon MDT Thursday for WYZ110-112-116. Winter Weather Advisory until noon MDT Thursday for WYZ114. Winter Weather Advisory from midnight tonight to noon MDT Thursday for WYZ115. Dense Fog Advisory until 6 PM MDT this evening for WYZ116. NE...Freeze Watch from late Thursday night through Friday morning for NEZ002-003-019>021-054-055-095-096.