textproduct: Cheyenne

KEY MESSAGES

- Unsettled weather returns to the area today, with chances for showers and thunderstorms this evening through at least Tuesday.

- A cooling trend begins Monday with near or slightly below average temperatures expected mid-week. Another warming trend will resume for the end of the week.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 152 AM MDT Mon Sep 28 2026

Upper-level troughing will continue across the western CONUS to start the week. A fetch of southwesterly flow aloft originating in the Pacific Ocean at the base of the upper-leve trough, will continue to funnel moisture into the region. Per the NAEFS Mean Precipitable Water, precipitable water values will remain at and above the 90th percentile through the first half of the week, favoring continued rain chances across the CWA. Down at 700mb, the CWA will be sandwiched between the trough off to the west and the ridge across the Central Plains into western portions of the Midwest. As a result, 700mb height gradients will increase, leading to a low-level jet around 40kts across the western Nebraska Panhandle throughout the day today. This low-level jet will shift easterly during the afternoon hours today as the ridge starts to move further to the east. 700mb temperatures will peak in the 6 to 9C range this afternoon, leading to surface temperatures in the mid-60s to low- 80s. A weak 700mb cold front will move through overnight tonight into early Tuesday morning, dropping 700mb temperatures into the 4 to 6C range overnight and back into the 6 to 8C in the afternoon. Temperatures on Tuesday will be cooler, thanks to this front, with highs in the low-60s to low-70s everywhere. Precipitation chances return Tuesday afternoon, though probability of precipitation remains fairly low, around 30 to 50%.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 152 AM MDT Mon Sep 28 2026

No major changes, please see previous discussion...

Tuesday night through the end of the work week could see a few areas of showers trying to lift up into the region, but this remains largely uncertain and low confidence as models remain split on the evolution of low pressure to our south and how far north moisture can make it. While some ensembles have begun to push the low and moisture associated with what will be the remnants of Hurricane Polo further northwards compared to the last few runs, overall this system still looks to be too far south to bring any further appreciable moisture to our area beyond Tuesday outside of maybe our farthest southeast zones, primarily Cheyenne County in the Nebraska Panhandle. The NBM continues to keep us high dry as well, with the above scenario remaining in the grids as of this writing. Still through Thursday POP chances aren't completely zero, but outside of the I-80 corridor and southward it's not looking favorable for any meaningful moisture in the long term. Otherwise we'll see a very slight warming trend on Wednesday, with temperatures warming a few degrees with widespread 60's and a few 70's expected, but a second cold airmass should drop us right back down into the widespread 60's on Thursday. Friday and Saturday high pressure over the southwestern US will allow for a warming and drying trend, returning us to several degrees above normal with highs in the 70's across the region. Sunday flow turns more northwesterly and a glancing upper level trough will help push a weak cold front into the region, bringing temperatures back down to near normal, but a lack of notable moisture will keep our precipitation chances almost nil and provide little more than a brief cool down to end the long term forecast.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1124 AM MDT Mon Sep 28 2026

Moist southwest flow aloft will continue.

Wyoming TAFS...High confidence in VFR prevailing. Isolated to scattered showers will prevail through the afternoon, with an increase in shower coverage expected with diurnal heating until early this evening, thus will go with prevailing -SHRA at Rawlins and Laramie through this afternoon, with prevailing light showers at Cheyenne late this afternoon. Adequate surface gradients will lead to wind gusts up to 23 knots this afternoon.

Nebaska TAFS...Confidence is high for VFR continuing. Expected shower and thunderstorm coverage warrants PROB30s at Chadron, Alliance and Sidney late this afternoon, with showers in the vicinity at Scottsbluff. At all sites except Scottsbluff, thunderstorms will produce gusts up to 35 knots with brief MVFR ceilings. surface pressure gradients suggest winds gusts up to 30 knots through late afternoon.

CYS WATCHES/WARNINGS/ADVISORIES

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