textproduct: Cheyenne

KEY MESSAGES

- An unsettled weather pattern will continue into the weekend with daily chances for afternoon/evening showers and thunderstorms.

- Strong to severe thunderstorms could be possible Friday and into the beginning of next week.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 325 AM MDT Thu May 28 2026

Today is a wash, rinse, and repeat of yesterday. Some showers may produce this morning as skies remain overcast through the day. The upper level low will remain cutoff from the main upper level flow. A stream of vorticity looks to eject from the cutoff low to give us a chance of showers in the afternoon and evening. With the overcast skies limiting convective initiation, shower coverage looks very limited today as well as very limited shear needed to sustain any shower/storm potential. There is a slight possibility of showers lingering into the overnight period however forcing seems to wane into the overnight period leading to low confidence in showers past 8pm. Friday, the upper level low will push into Utah becoming slightly negatively tilted by Friday afternoon. The RRFS suggests a couple pockets of 30 knot shear but, hi-res guidance generally depicts weak to no shear aloft. Therefore showers will have trouble utilizing CAPE and intensify into a possible thunderstorm. Most hi- res models paint a diagonal band of MUCAPE between 1500 and 2500 from Converse county, WY to Cheyenne county, NE. For now, a brief period of convection capable of producing wet microbursts is possible Friday afternoon into the evening hours before capping looks to return across the region. Uncertainty is fairly high at this time, due to the capping element as well as the uncertainty in sufficient lift across the region. However, there is a Marginal Risk (Level 1 of 5) for severe weather on Friday across far southeast Wyoming and western Nebraska.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 316 PM MDT Wed May 27 2026

An active, but very messy, pattern is in store for southeast Wyoming and western Nebraska through the mid-term and long-term forecast periods. Upper-level troughing will broadly be the dominant upper- level feature throughout the next week or so. Starting Friday, an upper-level trough and low will dig across Nevada and Utah, taking on a stout negative tilt by Friday afternoon with strong southerly flow throughout the atmosphere across the CWA. The NAM suggests between 2500 and 3200 J/kg of MUCAPE across western Nebraska late Friday afternoon into the early evening hours, but minimal to no shear to support the significant CAPE values. Therefore, organized storms may be difficult to reach. However, forecast soundings from the NAM across the southern Panhandle suggests Precipitable Water values of 1.2in, SBCAPE values of 3600 J/kg, and DCAPE values of 840 J/kg all suggest the potential for wet microbursts across western Nebraska, if storm initiation can occur. As of this forecast package, the biggest question for this set up will be whether there is enough forcing with the upper-level trough digging through and/or the 500mb vorticity lobes ejecting across the region, as well as the possibility of remaining capped all day due to low-level overcast cloud coverage. For now, a brief period of convection capable of producing wet microbursts is possible Friday afternoon into the evening hours before capping looks to return across the region. Uncertainty is fairly high at this time, due to the capping element as well as the uncertainty in sufficient lift across the region. However, there is a Marginal Risk (Level 1 of 5) for severe weather on Friday across far southeast Wyoming and western Nebraska.

The upper-level low will continue to impact the region through Saturday through Tuesday due to the messy evolution of this upper- level system. Both the GFS and ECMWF suggest the upper-level low closing off on Saturday and rotating northward along the Rocky Mountains before a secondary low pushes into the Pacific Northwest. This low will rotate across the region and head northward before a more defined trough develops Monday night into Tuesday and finally moves off to the east by early Thursday morning. With some version of troughing or upper-level lows across the CWA for multiple days, it is looking to be a fairly wet next several days with daily chances for afternoon showers and storms. Additionally, upper-level trough will keep surface temperatures quite comfortable with daily high temperatures Friday through Wednesday in the 70s and low-80s for all locations across the CWA. 700mb flow will largely see some for of troughing or 700mb lows throughout the next week or so, further supporting daily shower and storm chances.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1138 AM MDT Thu May 28 2026

Fog and low clouds are mixing out east of the Laramie Range, where CIGs are expected to rise resulting in VFR conditions with a standard diurnal cumulus field based around 6-10 kft. Can expect a few showers and thunderstorms mainly for KLAR, KSNY, and KAIA into the late afternoon hours given lingering low-level moisture. However forcing for ascent is weak and deep-layer vertical wind shear is negligible, so these showers/storms are expected to be brief.

Low-level moisture will remain in place into the overnight and early morning hours for KCYS, KBFF, KSNY, and KAIA as we remain under SSE upslope flow. This will result in MVFR conditions and low cloud development mainly after 06Z with CIGs ranging from 1-3 kft. Similar to what we saw earlier this morning, CIGs are expected to lift to VFR by 15Z as diurnal heating and mixing begins to occur towards the end of the TAF period.

CYS WATCHES/WARNINGS/ADVISORIES

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