textproduct: Cheyenne

KEY MESSAGES

- Daily shower and thunderstorm chances continue Monday through the end of the week with slightly above average temperature expected until Thursday.

- Showers and Thunderstorms Monday afternoon may produce strong gusty winds over southeast Wyoming and western Nebraska through this evening.

- Near average temperatures through Wednesday, with a slight warming trend late this week and into the weekend.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 210 AM MDT Mon Aug 24 2026

Current KCYS radar loop shows some lingering showers and embedded thunder across central and south central Wyoming early this morning. Not much forcing in the area, so activity is likely due to remnant outflow boundaries and convection west of the area from Sunday afternoon. Expect this activity to dissipate over the next few hours with relatively quiet conditions expected early Monday morning.

Similar convective environment this afternoon in comparison to Sunday, but with more midlevel forcing and a bit more low level convergence along the Laramie Range and the southeast Wyoming eastern plains as a cool front dips south into the region later this afternoon. A poorly defined dry-line will also drift east today as westerly winds increase slightly ahead of the front. These factors should be enough to initiate high based convection for much of the area, especially southeast Wyoming and far western Nebraska. Models show inverted V soundings across most of the region into the afternoon, but a few locations in and around Sidney, Alliance, and Chadron continue to show 800 to 1600 j/kg of MLCAPE with marginal shear values around 25 to 30 knots. Initially, expect most of the convection to produce strong gusty winds...even without any thunderstorms due to the dry boundary layer up to 500mb. Once we head into the late afternoon and evening hours, the surface cool front will push south towards the I-80 corridor and North Platte River Valley. Expect a better chance of rain showers and thunderstorms during this time period, so kept POP between 25 to 40 percent into the late evening hours. The Marginal Risk for severe thunderstorms remains over the whole forecast area, mainly for strong gusty winds between 55 to 70 MPH. Further east, SPC has introduced a Slight Risk where the more favorable convective environment is located. Portions of western Nebraska may also see some marginally large hail and strong winds over 65 MPH this afternoon through later this evening. Some of this convection may linger past midnight as moisture advection and some jet energy aloft remains over the area through Monday night.

Weather becomes more active starting on Tuesday as models show another potent shortwave, embedded in northwest flow aloft, digging southeast across the I-25 corridor and the eastern plains. Thankfully, 0-6km shear relaxes a bit behind the front with shear values mainly below 25 knots. Heavy rainfall looks to be more of a concern due to slow storm motion/weak winds aloft...with a Marginal Risk for Excessive rain, especially near the Colorado border. Cooler temperatures are also expected with high temperatures around 80 to maybe 85 degrees east of the I-25 corridor. Increased POP up to 50 percent for high-end scattered thunderstorms near the I-80 corridor. May need to extent the highest coverage of thunderstorms further east into the southern and central Nebraska Panhandle depending on low level stability and the amount of CIN. However, the opposite may present a problem as well, and may need to lower POP across the area if low clouds and CIN are too strong along and east of the Laramie Range. For now, will continue to monitor and update as needed.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 252 PM MDT Sun Aug 23 2026

No major changes to the overall long term forecast as we see conditions slightly warmer than average to start the period and then by the end of the week into next weekend we warm back up to several degrees above average with monsoonal moisture providing a daily chance of thunderstorms with a low end severe risk generally expected each day. At the upper levels, a strong ridge of high pressure will control the Western US, and should continue to hold control until the end of the week when a deep low will approach the western Canadian coastline. This feature may begin to move inland and could interrupt our pattern by late next weekend, but until then expect largely similar conditions each day. Moisture at the surface may begin to slowly dwindle, and by the late week into the weekend elevated fire weather concerns may begin to arise as minimum daytime RH values drop back into the teens. Still, daily PWAT values will sit around 120-130% of normal, and between daytime instability and weak disturbances riding the periphery of the ridge, we should still see thunderstorm chances each afternoon with a low end severe threat possible. At the surface meanwhile, a cold front will stall out on Tuesday and then begin advancing back eastwards as a warm front but should become very slow moving to even stationary, helping to fuel storm initiation through the end of the week. Overall it will be more of the same as we remain in a fairly stagnant pattern through the period.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 600 AM MDT Mon Aug 24 2026

Tricky Aviation forecast today with multiple lines of showers and thunderstorms possible as a shallow cold front moves south across Wyoming and the eastern plains into this evening. Strong gusty winds will be the primary concern with this activity.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail over the next 24 hours. Low confidence with impacts from showers and thunderstorms for all terminals today and tonight, mainly due to uncertainties with coverage. Added VCSH and PROB30 for gusty winds due to thunderstorms and gusty showers. Can't rule out some gusts of 60 knots late this afternoon through late this evening (22z to 06z) and brief MVFR VIS.

CYS WATCHES/WARNINGS/ADVISORIES

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