textproduct: Cheyenne

KEY MESSAGES

- A significant, late season snow storm is moving across the area. The greatest impacts are between Tuesday afternoon and Wednesday morning.

- Snow will accumulate over 5500 feet in elevation, with significant snowfall expected in and near the Snowy Range and southern Laramie Range

- Snowfall is expected to be heavy and wet, which could damage tree limbs and produce power outages.

- Travel impacts due to snowfall are expected along Interstate 80 between Rawlins and Cheyenne, and Interstate 25 between Wheatland and the Colorado state line.

- Impacts may extend eastward on Interstate 80 towards Kimball, mainly Tuesday afternoon and Tuesday night as colder air moves into the area.

- Drier, warmer, and windier weather returns to the area for the second half of the work week.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 259 PM MDT Tue May 5 2026

The reinforcing trough is expected to come late this evening into tonight. The meso-low can be see on mid-level water vapor quickly diving southeast from Montana. This Meso-low should provide additional synoptic lift to produce some stronger snow rates and decent accumulations. The RAP also predicts another large band of FGEN to sit over the southern portion of Southeast Wyoming stretching from Carbon to Laramie County. The Hi-res models adds another 4 to 8 inches for Cheyenne and another 10 to 12 inches for the Foothills/Summit area. However, if the band moves quicker than forecasted then a lot less accumulation would be expected as the 10th percentile only has about 2 inches for Cheyenne and maybe 6 to 10 inches for the summit and foothills area. On the other hand if this wave over performs we could see another 8.0 to 10 inches for Cheyenne and 12 to 18 inches for the Summit and foothills as depicted in the 90th Percentile. Model guidance still shows some lingering showers that last into Wednesday afternoon, however with the dry air mass moving into the region and lack of synoptic support from the fleeting system, pops were reduced from NBM past 15z (9am) Wednesday. 15 percent pops were kept along the southern counties until 21z(3pm). Tonight, 700mb temperatures will drop between -9 to -12C. Temperatures will drop into the 20's tonight essentially freezing the currently wet roads. The slick icy roads may make travel a little more difficult and hazardous at times.

LONG TERM /WEDNESDAY NIGHT THROUGH TUESDAY/

Issued at 400 AM MDT Tue May 5 2026

Drier air will move in overhead Wednesday night, leading to clearing skies. Areas with fresh snow cover (primarily Laramie and Cheyenne) may have a window to see temperatures drop quickly before westerly winds and strong warm air advection returns late Wednesday night or Thursday morning. We could see overnight lows reached in the evening, with warming occurring later as the winds pick up. The arctic high pressure moving through over the next few days will be settled in over the interior Rockies by Wednesday night. On the large scale, the overall weather pattern will shift into a northwest flow pattern with a ridge located over the West Coast, and the persistent upper level trough remaining over the Hudson Bay region. Another progressive shortwave will approach the area as early as Thursday. This feature will be accompanied by a surface trough, which will drop surface pressure over the High Plains. As a result, we will need to watch for the potential for a gap wind event Wednesday night into Thursday morning. High wind probabilities remain around 30 to 40%. Interestingly, this event appears to a low- level / surface driven gap wind event, which is somewhat unusual this late in the wind season. 700-mb winds look unlikely to exceed 50 knots, and 700-mb height gradients are fairly unimpressive. For now, winds were nudged towards the NBM 90th percentile in the official forecast, but remain below high wind criteria. Both the Arlington/Elk Mountain and I-80 summit areas will have ample snow on the ground when the winds pick up. We could have some blowing snow concerns, but there is a lot of uncertainty in this owing to the snow consistency and how much thawing (i.e. wetting the snow) can occur on Wednesday.

Expect a breezy to windy day elsewhere Thursday with temperatures quickly recovering to near seasonal averages. The Laramie to Cheyenne corridor will remain cool, but the rest of the area should warm above average. The next shortwave aloft will arrive late Thursday, and will bring a chance scattered showers and isolated thunderstorms across the area Thursday afternoon and Thursday night. This will not bring much rainfall, but temperatures will be warm enough that we will not have to worry about snow. The northwest flow pattern should remain fairly locked in place through the weekend. Overall, expect temperatures near seasonal averages and breezy to windy northwest winds every day. We will also remain fairly unsettled, with chances for showers each day.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 456 PM MDT Tue May 5 2026

Snow and rain will continue to drive low clouds and IFR to LIFR conditions through the overnight hours for all sites except for KCDR/KAIA where only mid level clouds and a passing shower are anticipated. Tomorrow morning, conditions will begin to clear and we should see precipitation exiting and CIGs lifting and clearing. By tomorrow afternoon, all sites should have mid to high level or clear skies with winds light at around 10 knots or less.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Winter Weather Advisory until 9 AM MDT Wednesday for WYZ103- 105-106-112-119. Winter Weather Advisory until 9 AM MDT Wednesday for WYZ104- 109. Winter Storm Warning until noon MDT Wednesday for WYZ110-114- 116-117. Winter Storm Warning until 9 AM MDT Wednesday for WYZ115-118. NE...Winter Weather Advisory until 9 AM MDT Wednesday for NEZ054.