textproduct: Cheyenne

KEY MESSAGES

- Lower coverage of showers and thunderstorms today, mainly further south near the Colorado border and western Nebraska. Brief strong gusty winds and locally heavy rainfall expected with this activity into this evening.

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

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 252 PM MDT Sun Aug 23 2026

Another active afternoon and evening is forecast. Storms have already begun to appear on radar early this afternoon, albeit not many. Coverage of storms will likely be less than yesterday with more dry air present from westerly winds aloft. A weak dryline is also present on observations across the CWA, roughly running along the Interstate 25 corridor. Behind the dryline remains fairly quiet with just a few cumulus fields. Ahead of the dryline is where storms currently are in Nebraska. The Nebraska panhandle is also where the highest instability is, with mesoanalysis suggesting more than 1500 J/kg of SBCAPE. Shear is decent, but likely not enough to get very strong storms. A few isolated severe storms are likely, with initial discrete cells posing a hail risk. As afternoon progresses to evening, the threat will switch to more of a wind one, with storm clusters entering the far western portion of the CWA. The intensity of these storms will be weaker than the ones in the Nebraska panhandle, but severe wind gusts will still be possible due to DCAPE values in excess of 1200 J/kg from the dry surface. Showers and storms will continue through the evening hours with a few lingering showers possible after midnight.

Rinse and repeat the same song and dance again for Monday. The environment looks similar to Sunday but with better forcing from an upper-level shortwave moving through the ridge. Coverage and intensity of storms on Monday will likely depend largely on where the weak dryline can set up. Some models push the dryline far enough east out of the CWA where the more intense storms will not impact the forecast area. Newer CAM guidance has begun to recede the dryline further back into the Nebraska panhandle which will likely result in storm development during the afternoon hours. Initial discrete cells that develop will pose more of hail threat, but will shift more towards a wind threat as they cluster. Much like Sunday, showers and weaker storms will enter the western portion of the CWA during the evening and move eastward. Wind will be the primary concern with these given the drier low-levels and high DCAPE values. Severe wind gusts cannot be ruled out. Showers will linger through the overnight hours.

LONG TERM /TUESDAY THROUGH SATURDAY/

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 /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1125 AM MDT Sun Aug 23 2026

VFR conditions expected over the next 24 hours. Added a mention of showers and/or thunderstorms in all sites due to recent high resolution model guidance, but pinpointing exact storm activity is a bit more difficult today and these probabilities are still on the low side. Winds breezy, 15-30 knots, stronger and more erratic near any precipitation activity. Winds should weaken overnight into tomorrow morning and become 10 kts or less. CIGs will generally be mid level, with some clouds nearing low level with thunderstorms, lifting and clearing overnight into tomorrow morning.

CYS WATCHES/WARNINGS/ADVISORIES

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