textproduct: Cheyenne

KEY MESSAGES

- Warming and drying trend expected through the end of the week.

- Precipitation chances return for the beginning of next week.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 114 PM MDT Fri Sep 4 2026

Current conditions are warm and dry area wide with mostly clear skies for most locations. Along mountain ranges there are some cumulus cloud development coinciding with increased insolation this afternoon. A few showers or storms could develop from these clouds in the later afternoon and evening hours along I-25 from Cheyenne to Douglas. The supporting mechanism for this activity would be a weak shortwave passage and monsoonal moisture aloft. PWAT values between 0.75 to 1.5 inch despite the low near surface moisture would additionally fuel showers/storms. CAPE values below 500 J/kg should limit the intensity of the storms moving off the mountains. Further east is the western extent of better moisture and instability. It is removed from the better force for ascent with the weak shortwave, so it is uncertain if storms will fire here. The best signal is for a storm to perhaps develop near Chadron and move east out of our area in quick order. Again this is of low confidence. Highs this afternoon will reach the low to mid 90s east of I-25 and low to mid 80s for points west. Some elevated fire weather conditions are possible, especially in Carbon, Converse, and Niobrara Counties given the low humidity and breezy conditions.

Tonight any lingering showers or storms along I-25 should dissipate by about 11 PM with the loss of daytime heating and our shortwave departing to the north. Lows in the 50s and low 60s are anticipated. Better moisture will be in place Saturday as the upper level trough over the Pacific Northwest sends yet another shortwave over the region. Storm coverage is expected to be greater as a result. Uncapped CAPE values generally around 500-1500 J/kg and shear 25-30 knots would promote clusters of multicellular storms. An isolated occurrence of severe caliber winds could manifest from any consolidated cold pools underneath these clusters. DCAPE values between 1000-1500 J/kg are certainly high enough to support this risk, though some low level dry air entrainment would hinder this somewhat. The SPC has a marginal risk for severe weather primarily for our Nebraska Panhandle areas. PWAT values between 1.0 and 1.5 inches and slow/training storms would make flooding an isolated concern. Highs in the afternoon are very similar to those seen Friday, generally in the 90s east of I-25 and 80s west. Overnight increasing cloud coverage and shower activity starts spilling over from the Pacific system moving closer to the area from the west.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 532 AM MDT Fri Sep 4 2026

Sunday, the low over the Pacific Northwest starts to push against our upper level ridge as it tries to push further into the interior of western United States. When this occurs more of the monsoonal moisture will feed over our region priming the Intermountain west for more storm activity. The storm coverage will slowly increase as well as more moisture feeds into the region. The system will inch towards the Intermountain West and start to flatten our ridge.

The trend of showers and thunderstorms continue through Monday and Tuesday as the stubborn trough to the northwest finally ejects into the central plains. While moisture will remain high, a lobe of drier air associated with a ridge to the east may be pulled in ahead of the trough which would reduce rain potential. However, since the trough is ejecting it is possible that cyclogenesis occurs nearby increasing the severe weather potential. Some machine learning models are highlighting an uptick in that potential for the Nebraska Panhandle area. The details of how this unfolds will be ironed out as we get closer.

The remainder of the long term is in a drying trend. The ridge noses in. This would not completely shut down storm activity.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1125 AM MDT Fri Sep 4 2026

VFR conditions are expected to prevail through the forecast period. Winds are being observed higher than progged in model guidance and previous forecasts. As such a bump in winds was added in the short term group for some terminals. A few afternoon and evening showers and thunderstorms are possible in high resolution model solutions. The greatest potential exists at KCYS where nearby storms could produce lightning and variable gusts. A smaller chance at KCDR of storms as well after 21z. Outside the isolated convection, winds should calm and remain weak going into the evening and into tomorrow, becoming variable at times. Increasing cloud coverage late in the forecast period can be expected ahead of the next shortwave.

CYS WATCHES/WARNINGS/ADVISORIES

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