textproduct: Cheyenne

KEY MESSAGES

- Cold front will move through Friday night, leading to a cooler day on Saturday.

- Storm chances increase on Sunday with the potential for severe weather.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 223 PM MDT Fri Sep 11 2026

Dry and windy conditions persist this afternoon ahead of an incoming cold front. This is fueling Red Flag conditions, mainly for areas east of the Laramie Range. Increased moisture aloft from a shortwave that moved across the area last night has lead to some cumulus fields developing this afternoon. There is some elevated instability as well as some lift from the approaching front. This could lead to a few isolated showers and storms developing later this afternoon and evening. Given the dry surface, it is likely that not much precipitation will make it to the ground. Wind and dry lightning will be the main concern in any storms that do develop today. The cold front will move through later this evening, putting an end to the Red Flag conditions and shower chances.

A pleasant Saturday is expected for most of the forecast area. Temperatures will be much cooler behind the front, with highs in the upper 70s to low 80s. There is another chance for isolated showers and thunderstorms from another weak shortwave, however there will be very little instability and shear in the post-frontal environment. Therefore severe and long lived storms are unlikely. Sunday looks more promising for storms and severe weather. A stronger trough will begin to push into Wyoming, raising temperatures and advecting moisture into the CWA. Instability will be much higher, with CAPE values rising well above 1500 J/kg. Ample shear and even high SRH values in the Nebraska panhandle make severe weather seemingly likely on Sunday. However, model soundings do show a strong capping inversion for much of the day which could affect severe weather potential. Will continue to monitor the storm threat for Sunday over the next few model cycles.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 223 PM MDT Fri Sep 11 2026

Sunday night into Monday morning shows a cold front passing over the CWA. After this front moves out, a ridge starts to build, bringing cooler temperatures and dryer air. Some storm and shower activity is possible Tuesday evening with return flow. A shortwave passes through on Thursday evening, allowing the ridge to continue to build. On Friday the ridge gets pushed out by a trough forming over the region. Some models are showing precipitation potential Friday afternoon, but more to come on that as we get closer. 700mb temperatures are in the 10-15C range in this long term period. Temperatures start to cool off and feel more like fall as the week progresses.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1001 PM MDT Fri Sep 11 2026

A weak cold front has pushed through the area this evening, shifting surface winds from westerly to either northerly or northeasterly. There are low probabilities (<15%) of KCYS and the Nebraska terminals seeing low cloud development, primarily from 09Z to sunrise given the NE upslope flow. Confidence isn't high enough given current obs/trends to include a PROB30 group for MVFR cigs. Winds will shift to more out of the SE tomorrow at 10-15 knots east of the Laramie Range. KLAR and KRWL will maintain westerly flow with gusts as high as 30 knots.

CYS WATCHES/WARNINGS/ADVISORIES

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