textproduct: Cheyenne

KEY MESSAGES

- Red Flag Warning in effect for Converse and Niobrara Counties.

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

- Precipitation chances return for the beginning of next week.

SHORT TERM /THROUGH TONIGHT/

Issued at 201 PM MDT Wed Sep 2 2026

A few thunderstorms are already popping up on radar early this afternoon as a strong shortwave swings through the main trough over the Pacific Northwest, sending some weak vorticity maxes into Wyoming. Mesoanalysis shows very little MLCAPE present through the afternoon with weak shear so showers and storms will be short-lived. The surface remains dry, with observations showing dewpoints in the 30s and 40s. Model soundings show steep inverted-V profiles, leading to DCAPE values well over 1000 J/kg. So while severe storms are not anticipated this afternoon and evening, a few rogue gusts over 60 mph will be possible. Hi- res guidance shows storms continuing through the evening with a few lingering showers possible after midnight. Outside of storms, some background windiness can be expected across southeast Wyoming this afternoon. A weak 250 mb jet currently sits over the CWA, so gusts over 45 mph can be expected, especially west of the Laramie Range.

With the shortwave moving into Canada, the CWA will remain sandwiched between a stagnant trough over the Pacific Northwest and a broad ridge over the eastern half of the country. The resultant weather on Thursday will be quiet, with warm temperatures expected east of the Laramie Range and seasonable temperatures west of the range. High temperatures east of the Laramie Range will be a few degrees warmer compared to Wednesday as warmer 700 mb air moves into the CWA. Highs will reach the mid 80s to mid 90s which is about 5 to 10 degrees above average for the start of September. Highs west of the Laramie Range will be in the 70s, which is more seasonable for this time of year. The forecast area will be more in the influence of the ridge on Thursday, so mostly sunny skies are expected with little to no chance of precipitation. Breezy conditions will continue for areas west of the Laramie Range under southwest flow. Near identical conditions are expected on Friday. Temperatures will be a few degrees warmer than Thursday as the ridge axis actually retrogrades back westward toward the center of the country. Sunny skies will still prevail through the day Friday with continued breeziness out west.

LONG TERM /THURSDAY THROUGH WEDNESDAY/

Issued at 201 PM MDT Wed Sep 2 2026

Saturday...Southwest flow aloft prevails. Looks like with a minor stream of the monsoonal moisture tap, we anticipate isolated to widely scattered showers and thunderstorms in the afternoon and evening.

Sunday...The precipitable water values increase somewhat as monsoonal moisture increases. With that said, expect scattered afternoon showers and thunderstorms to form over and near our Snowy Range and Laramie Range in the afternoon due to orographic effects and differential heating, with most of the convection propagating over the Nebraska Panhandle in the evening.

Monday...Somewhat drier air aloft moves overhead under southwest flow aloft, which should correspond to an areal decrease in afternoon and evening showers and thunderstorms.

Tuesday and Wednesday...Again, somewhat drier air infiltrates our western counties using precipitable water values, with a bit better moisture further east, thus isolated to scattered showers and thunderstorms expected mainly over the mountains and eastward.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 539 PM MDT Wed Sep 2 2026

Showers this evening linger over KCYS, KCDR, and KBFF before moving out later this evening. These showers are producing some rain and gusty winds. Gusty winds are to be expected over this TAF period, especially over the Wyoming terminals. VFR conditions are expected to prevail throughout the TAF period.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning from noon to 7 PM MDT Thursday for WYZ417-418. NE...None.