textproduct: Cheyenne

KEY MESSAGES

- A slight chance of rain is possible for the southern Nebraska panhandle Wednesday afternoon into Wednesday evening.

- Cooler temperatures continue through Thursday, but warmer and drier weather will prevail Friday through early next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 259 AM MDT Wed Sep 30 2026

A strong upper-level closed low will traverse the Four Corners region today, sending some moisture northward into the Interstate 80 corridor. The surface low associated with this system will move northeastward into Kansas by the end of the day, bringing minor chances for precipitation. Most models, both Hi-Res and synoptic, are in agreement that most, if not all, precipitation will stay south and east of the forecast area. However, cannot rule out a light shower or two in the southern Nebraska panhandle during the afternoon and evening hours as the surface low moves into Kansas. Current satellite imagery shows cloud cover beginning to push into northern Colorado. These clouds will eventually make their way into southeast Wyoming and western Nebraska. As a result, increasing cloudiness can be expected throughout the day. The cloud cover will lead to a cool day, but still seasonable for this time of year with highs in the 60s and 70s. Clouds will gradually decrease Wednesday night, with a stray shower still possible overnight for the southern Nebraska panhandle.

Thursday will mark the start of a dry pattern as the low pressure system moves further east. Clouds will continue to clear out during the morning hours, leading to mostly sunny skies by the afternoon. Upper-level ridging building over the Four Corners region will help clear clouds out as well as keep precipitation chances low. High temperatures will be similar to Wednesday with highs in the 60s and 70s. With mostly clear skies expected Thursday night, overnight lows will be on the chilly side with 40s and potentially a few 30s possible.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 212 PM MDT Tue Sep 29 2026

Generally tranquil weather will persist through much of the long- term period. Large-scale ridging will dominate the weather pattern over the western CONUS resulting in generally mild above-average temperatures and limited precipitation chances over southeast Wyoming and western Nebraska. This ridging pattern is, broadly speaking, a general result of the highly active tropical pattern over the eastern Pacific. As the firehose of EPAC tropical storms move west and then recurve to the north in the mid-latitudes of the central Pacific, potent synoptic troughing is noted over the Bearing Sea/Gulf of Alaska which thus drives downstream ridging over western North America. These types of stable-synoptic-wave patterns can often persist for weeks or more, locking in high-confidence forecasts over much of the west including our region.

Regarding local details in the forecast, expect above-average temps from Friday onward. High confidence exists in temps around 5 degrees above average this weekend (low to mid-70s east of the mountains) and highs 10 to 15 degrees above average through next week. Despite the drier weather in place late this week and through the weekend, rising heights should result in overnight lows remaining above average as well. This should hold off any threats of frosts (or freezes) for any populated area of southeast Wyoming outside of the mountains. Afternoon RH values will drop to near or slightly below 20% throughout the weekend during the afternoon hours across all of southeast Wyoming and portions of the Nebraska panhandle. However, generally light surface flow out of the west less than 20 mph will likely preclude the need for any fire weather headlines. Overall, given the synoptic pattern described earlier in this discussion, forecast confidence is quite high throughout the entire long-term period with limited impacts expected.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 1058 AM MDT Wed Sep 30 2026

VFR conditions will prevail at all terminals this afternoon. Expect high cirrus clouds over CYS and over the southwestern Nebraska terminals. Ceilings will lower at SNY later this afternoon but should remain above MVFR thresholds. Forecast trends have indicated that any shower activity should stay south and east of SNY leaving all terminals dry through the forecast period. Dry weather and VFR expected at all terminals on Thursday.

CYS WATCHES/WARNINGS/ADVISORIES

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