textproduct: Cheyenne

KEY MESSAGES

- Temperatures bounce back and forth through the week with Tuesday the coolest day, followed by a Wednesday warmup, Thursday cool off, and Friday back up above normal again. Temperatures over the weekend should be around near normal.

- Daily shower and thunderstorm chances continue through the week as well with activity remaining

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 1223 AM MDT Tue Sep 15 2026

Upper level pattern will see troughing moving out of the area and overall southwesterly to westerly flow taking over, followed by ridging building in on Wednesday and then a quick and weak shortwave trough riding the periphery of that feature on Thursday. At the surface, we'll be in a post-frontal environment today, with a warm front lifting up on Wednesday and another modest cold front passing through on Thursday. Under this pattern, we'll see a nice rollercoaster to temperatures as highs will be at their lowest today with 60's to only mid 70's for the day, but tomorrow's warm front will then bring us back above normal in the 70's to 80's, followed by another cool off on Thursday as we drop back into the 70's and approach closer to near normal for the day. Meanwhile, flow today should allow for a few showers and storms to develop across the high terrain of our western zones mainly in Carbon and Albany Counties, but this activity will be limited by the modest PWAT values present alongside meager forcing mostly driven by upslope flow. Into Wednesday increasing moisture should allow for a bit more widespread isolated to scattered shower and thunderstorm development, but once again a lack of favorable severe ingredients will preclude stronger storm development. Seeing a little bit of instability in the Nebraska Panhandle by the evening though, so maybe a storm could become stronger if it moves into this area but unlikely. And Thursday increasing moisture plus the quick moving shortwave will present widespread showers and thunderstorms through the day, but with how quickly this feature moves across we won't have the time to develop stronger ingredients and so once again garden-variety storms are anticipated. Finally, pressure gradients should allow for a modestly breezy day today but shouldn't be nearly as strong as Monday ones, with winds declining on Wednesday and Thursday.

LONG TERM /FRIDAY THROUGH MONDAY/

Issued at 240 PM MDT Mon Sep 14 2026

Ahead of a Pacific upper level low a few embedded shortwave impulses in the southwesterly flow aloft are anticipated to pass through the area. The best resolved of these shortwave troughs is anticipated Thursday and will be attended by an impressive fetch of monsoonal moisture. Ensemble PWAT values are progged to be near or just outside of the climate maximum. Widspread 1 to 1.5 inch PWAT values could lead to proficient rainfall potential. GFS forecast soundings for some spots in the NE Panhandle feature a near saturated profile with an impressive depth to the warm cloud layer for this area. The CAPE values are rather paltry however. At the surface a weak lee cyclone may develop and move NE over the Panhandle locations. Behind this cyclone cooler air filters in to drive afternoon temperatures a few degrees lower than Wednesday. The WPC has a marginal risk of excessive rainfall over our area. Fog is a possibility in the morning hours east of I-25.

Friday continues the cloudy and wet trend while the Pacific trough continues to inch eastward. The fetch of monsoonal moisture continues with widespread light showers and thunderstorms. The near surface layer does dry out limiting greater rainfall potential. The marginal risk of excessive rainfall continues in the latest outlook.

This weekend the trough begins to flatten and decay as it nears our neck of the woods. Continued shower and storm activity in the afternoon and evening hours is likely to continue, but by this point the monsoonal flow could be largely shut off with us on the dry western side of the trough. Southwesterly flow continues in the very long term with more embedded shortwave troughs which could provide a stormy start to the work week.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 523 AM MDT Tue Sep 15 2026

Mostly VFR conditions expected over the next 24 hours. A few low clouds have moved into KCYS bringing MVFR conditions, but these should move out within the next hour or two based on current model guidance. CIGs through the day into tomorrow should remain mostly mid to high level, with some clearing today before widespread cloudiness returns tonight into tomorrow morning. Winds breezy again today all sites with gusts between 20-30 knots, with many sites lessening overnight except for KRWL, KSNY, and KAIA where enhanced gusts likely through the remainder of the TAF period. Some showers may move into KRWL/KLAR tonight into tomorrow morning, but they should be fairly scattered and not expecting significant drops in flight categories from this activity.

CYS WATCHES/WARNINGS/ADVISORIES

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