textproduct: Cheyenne

KEY MESSAGES

- Snow showers will come to an end from north to south this morning. Slushy, icy, or slick conditions will affect the Wednesday morning commute in some areas.

- Winds will increase tonight in the wind prone areas of southeast Wyoming, then spread elsewhere Thursday.

- Scattered showers and isolated thunderstorms Thursday afternoon and evening will have the potential to produce gusty and erratic winds.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 400 AM MDT Wed May 6 2026

Snow showers continue to move across the I-80 corridor this morning, but we are nearing the end of this long duration late season snow event. GOES water vapor imagery shows the axis of the upper level shortwave moving from north to south across central Wyoming at this time. Drier air aloft is already moving into our northern counties, but moisture and lift remain in place further south. The trough axis should clear through the area between about 6am and 9am, bringing snow activity to an end. A cold airmass is firmly in place this morning, but the cloud cover over most of the area is keeping temperatures from dropping below the mid 20s to lower 30s and in most areas. The center of this cold surface high pressure system will move across the area today, keeping temperatures well below seasonal averages. Skies will clear form north to south, but most will see some sunshine by the end of the day today. As such, temperatures should warm above yesterday's highs. Laramie and Cheyenne will be the coldest, with highs in the upper 40s, but all other areas should reach the mid 40s to mid 50s.

Since we are in the midst of a very wintry weather pattern this week, it is only fitting that we will also have to talk about high winds. The aforementioned surface high pressure will get abandoned over the interior Rockies tonight. This will be enhanced by clear skies and plentiful radiative cooling over the fresh snowfall in north central Colorado. Meanwhile, the western ridge will recover and transition the area into a progressive northwest flow pattern. A fast moving upper level shortwave will push into the northern Rockies tonight. This will be accompanied by a surface trough, and as a result, we can expect to see surface pressure over the High Plains dropping rapidly. Thus, the pressure gradient across the area will strengthen this evening and into Thursday morning, peaking around 3am to 6am. This potential wind event appears to be entirely surface driven, and parameters aloft and at 700-mb are unimpressive. Surface driven events are rare this time of year, which reduces confidence. Surface pressure gradients are sufficient to produce high winds in some models, but not in others. Both in-house and NBM guidance gives approximately a 40% chance for high winds at each of the typical wind prone spots in southeast Wyoming. There is a little uncertainty in how the new snow will respond to the slightly warmer temperatures and limited sunshine today, but patchy blowing snow was introduced to the official forecast. If we get more sunshine than expected, that could remove the threat for blowing snow by wetting the snow and allowing it to bond to itself. Confidence was not high enough to a High Wind Watch this morning, but we will need to continue to minor this.

Northwest flow will spread into the High Plains quickly Thursday morning, setting up a fairly windy day across the area. Temperatures will recover to near or slightly above seasonal averages. We will be right back into a more typical spring-like weather pattern. This will still be a very progressive pattern though. The shortwave trough mentioned above will arrive Thursday afternoon, and provide some forcing for large scale ascent. Instability in the ballpark of 300 to 800 J/kg SBCAPE may be present over the High Plains, with moderately steep lapse rates and fairly good moisture. Shear will be unidirectional, but around 20 to 40 knots. As a result, the synoptic lift should be able to kick off scattered showers and thunderstorms, which will move quickly from northwest to southeast. These storms could produce gusty and erratic winds. A few gusts over 60 mph cannot be ruled out. These storms will be moving quickly, which will temper hopes for widespread beneficial rainfall. Still, brief moderate to heavy rainfall can be expected, with highly localized rainfall amounts in the 0.1 to 0.25" range anticipated. This activity will likely continue well into the evening hours.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 400 AM MDT Wed May 6 2026

A progressive northwest flow pattern will remain over the area through the weekend. This will be driven by a persistent ridge over the West Coast and troughing over the Great Lakes region. Temperatures should remain close to seasonal averages each day, with breezy conditions continuing. Winds will tick up on Friday night into Saturday as the next upper level shortwave trough makes its way through the area. We have another 20 to 40% chance for high winds in the wind prone areas with this feature, and increased chances for showers and thunderstorms over the High Plains.

The ridge will shift eastward early next week, sending temperatures up for Monday. This may extend into Tuesday and Wednesday as well, but ensembles differ in their handling of another upper level shortwave riding over the top of the ridge. About half of LREF members bring this feature through far enough south to knock temperatures down to near average for Tuesday, while the others keep the feature to the north, which would lead to a continuation of temperatures 10 to 20F above seasonal average. The warming trend will also likely increase fire weather concerns. While the recent rain and snow will probably be able to kick start a decent greenup in the I-80 corridor, those to the north remain quite parched with fuels ready to burn.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 526 AM MDT Wed May 6 2026

Conditions are expected to improve over the next few hours as snow comes to an end. LAR and CYS may still see VIS/CIG drops into MVFR or IFR for the next few hours, but should reach VFR by mid morning and remain there through the rest of the forecast period. Winds could be variable at times as the current storm moves out of the area.

Overnight, southwest winds will setup across the area, becoming gusty at Wyoming terminals. There may be some LLWS concerns in addition to occasional surface gusts to around 30 knots.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Winter Storm Warning until noon MDT today for WYZ110-114-116- 117. Winter Weather Advisory until 9 AM MDT this morning for WYZ112. Winter Storm Warning until 9 AM MDT this morning for WYZ115- 118. NE...None.