textproduct: Cheyenne

KEY MESSAGES

- Dry conditions and above average temperatures will continue through the work week.

- A pattern change is increasingly likely beginning around Sunday into early next week, but the details remain uncertain.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 145 AM MDT Tue Oct 6 2026

All models in good agreement through the middle of the week showing the upper level ridge axis gradually flattening out through Wednesday. This is expected to be a slow process with the lack of upstream Pacific disturbances influencing the mid to upper levels, but expect high temperatures not quite as warm as Monday with a slow cooling trend (if you can really call it that) by the end of the week. A shallow backdoor cool front on Wednesday will help in cooling things off a bit, but temperatures will still remain around 10 to 15 degrees above average.

Little to no precipitation is expected with dry conditions continuing through early Thursday morning. We're exiting convective season, so can't completely rely on buoyancy alone to generate showers across the area. As the backdoor cool front moves southwestward across southeast Wyoming on Wednesday, models show increasing low level convergence near the mountains. This will be our "best" chance for precipitation over the next 5 days across southeast Wyoming. High res models showing some shower activity developing along and south of the I-80 corridor from Rawlins to Cheyenne, but mainly added 15% to 20% POP to the mountains with mostly virga expected in the valleys due to a dry boundary layer. Otherwise, the majority of the forecast area will remain dry with occasional scattered clouds in the afternoon.

Record high temperatures are expected once again Tuesday for southeast Wyoming with afternoon high temperatures in the upper 70s to low 80s. Cheyenne, Rawlins, and Laramie have the best chance to see record highs around 80 degrees. Western Nebraska will get close, but highs may be a few degrees cooler compared to Monday. This, combined with higher daily records set back in the 1970's, will make it harder for breaking daily record high temperatures today...although record high low temperatures look more probable. Once the weak backdoor cool front moves through the region Wednesday, record highs are unlikely for most places along and east of Albany County.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 205 PM MDT Mon Oct 5 2026

High confidence in warm and dry weather continues through Saturday, but a major pattern change is increasingly likely beginning around Sunday.

Broad ridging will continue to dominate the western US through the end of the week. Ensembles are in pretty good agreement showing the strength of the ridge moderating just slightly on Wednesday and Thursday, so forecast highs will be just a few degrees cooler than today and tomorrow. Temperatures will be closest to records again at Laramie and Rawlins, as the core of the ridge will remain to our west. While humidity will remain low and lead to elevated fire weather conditions, winds are expected to remain light through this period. Therefore, critical fire weather conditions are unlikely. The ridge will start to amplify again on Friday into Saturday as its axis shifts rapidly eastward towards the central CONUS. 700-mb temperatures will remain around the climatological 90th percentile for this period. With the ridge moving east, flow aloft will turn more to the southwest, opening the door to increased wind speeds especially in Carbon, Albany, and Converse counties. While high winds are unlikely (10-20% chance) this may increase fire weather concerns for Friday and Saturday. In addition, a few ensemble members show some disorganized vorticity meandering through our area under the ridge during this period. Combined with the southwest flow increasing mid to upper level moisture, we may see isolated high- based showers returning to the forecast by the end of the week. Current chances for measurable precipitation remain slim.

Major changes are increasingly likely beginning around Sunday. While confidence is high that something will change, there is low confidence in what the new weather pattern will look like. Ensembles are unanimously showing some type of powerful Pacific trough approaching the area Sunday or Monday, but are in very poor agreement on exactly how this moves through the area. The LREF suite is split nearly 50-50 into two clusters. In one cluster, the Pacific trough moves through more quickly, and as an open wave. This would lead to a dramatic cool down on Sunday or Monday with higher chances for widespread freezing temperatures. Overall QPF expectations are lower in this scenario (widespread 0.1 to 0.4"), but the chance for snow falling in more populated areas would be higher. The other cluster of ensembles depicts the upper level low diving further south and closing off over the western US. The storm moves through much more slowly, leading to significantly warmer temperatures Sunday and Monday and a delayed cool down after the end of the operational forecast period. In this scenario, overall QPF expectations look considerably higher (widespread 0.4 to 0.8", but the chance for snow would be lower due to warmer temperatures when precipitation is falling. One other interesting tidbit is that ECMWF AIFS and GEFS AI members tend to strongly prefer the faster, drier, and colder former scenario. This will be an interesting event to watch for the performance of these relatively new guidance tools.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1122 PM MDT Mon Oct 5 2026

No major changes from the previous forecast as VFR conditions will continue to prevail across all terminals for the duration of this TAF period. Under mainly clear skies, with a few high clouds, expect variable winds less than 10 knots across all sites for the remainder of the overnight hours through Tuesday afternoon.

CYS WATCHES/WARNINGS/ADVISORIES

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