textproduct: Cheyenne

KEY MESSAGES

- Shower and storm chances are expected through the weekend. Strong to severe wind gusts will be possible, with moderate to heavy rain likely.

- Marginal Risk for severe thunderstorms Saturday with strong gusty winds possible.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 200 AM MDT Sat Aug 29 2026

Current IR Satellite loop shows mostly cloudy skies over southeast Wyoming and western Nebraska which is keeping nighttime temperatures in the 60s and 70s at 200 AM, not only for the eastern plains but the high valleys as well. A few light sprinkles are showing up on radar, but likely very little precipitation is reaching the ground with surface humidities below 50% across Carbon county. Therefore, pretty quiet weather this morning until about noon with stable conditions and mostly cloudy skies. However, active late summer weather pattern is expected to continue this weekend with additional thunderstorms likely for Saturday.

All models show the potent upper level trough near the Pacific NW coastline moving onshore today as a relatively strong 85 knot to 100 knot jet max develops and translates eastward into Wyoming this weekend. Although cloud cover today may keep instability at-bay early, upper level jet energy and remaining low to midlevel monsoon-like moisture will be enough forcing to aid in the development of scattered to numerous showers and thunderstorms this afternoon through this evening. Not only that, but expect several bands of thunderstorms to move through the area and expect some of this activity to linger into the late evening hours and possibly well past midnight tonight. A quick glance at models soundings (RAP, NAM, GFS) all show 30 to 45 knots of mainly speed shear with straight hodographs and roughly between 500 to 1000 j/kg of CAPE. With PWATs a little higher than average, these profiles suggest several lines of thunderstorms with strong gusty winds the primary hazard. Can't totally rule out some hail, but squall lines and multicell clusters will likely be the primary mode of thunderstorms today. These winds may top out near 70 MPH, especially over Carbon and Albany county where the "driest" airmass will be located with ample DCAPE and inverted-V soundings. High res models (HRRR, NAMNEST) show activity beginning as early as noon and continuing through the late evening hours with some pretty strong convection lingering past midnight and into the early morning hours of Sunday. High temperatures will be similar to Friday with afternoon readings in the mid 80s to mid 90s for much of the eastern plains, with slightly cooler temperatures for Carbon and Albany county because of the cloud cover and the potential for continuous thunderstorm activity through the afternoon.

Cooler temperatures for Sunday, but highs should still top out in the mid 70s to mid 80s for most of southeast Wyoming. Western Nebraska will remain pretty hot, but expect the afternoon highs in the low 90s to lower back into the 80s through the afternoon. Confidence of showers and thunderstorms is lower, mainly due to Saturday's thunderstorm activity likely persisting into Sunday morning for at least the Interstate 80 corridor. However, pacific jet energy and an associated upper level disturbance should be enough forcing to initiate widely scattered showers and isolated thunder through the afternoon and evening hours. There is a marginal risk for severe thunderstorms for most of western Nebraska and far eastern Wyoming Sunday afternoon as convective parameters looks suitable for some locally strong gusty winds. MLCAPE and SBCAPE remain around 1000 to 1500 j/kg across portions of eastern Wyoming and western Nebraska, with the NAM a bit more aggressive and over a larger area. Otherwise, both days should be pretty windy due to the upper level trough and jet max not far too our north. Expect wind gusts of 35 to 45 MPH, mainly Carbon and Albany counties and east central Wyoming.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 234 PM MDT Fri Aug 28 2026

A fairly stagnant synoptic weather pattern will last through much of next week. Looking at the big picture, ensembles are in strong agreement showing the upper level ridge migrating eastward, and setting up over the southern Plains or southeastern US for much of next week. A series of fairly potent upper level lows will move into the West Coast throughout the period as well. That leaves our area under steady southwest flow for much of the week.

Beginning on Monday, model guidance depicts a notable shortwave trough ejecting to the northeast out of the monsoon region. This will be accompanied by a surge in moisture which should support another round of scattered PM showers and thunderstorms. An early look at the overall setup suggests a typical monsoonal thunderstorm pattern with good forcing, but unimpressive instability. PoPs are currently around 30 to 50%, generally the scattered category, with locally heavy rainfall possible due to precipitable water remaining quite high. The limited instability presents a failure mode though. Several ECMWF ensemble members show heavy rainfall failing to make it far enough north to reach our area, likely due to the lack of instability, while GEFS members as a whole are more aggressive on thunderstorm coverage. Monday also looks like the coolest day of the week, with highs generally near seasonal averages.

Beyond Monday, precipitation chances look more limited but will not disappear entirely. Precipitable water looks to remain elevated for most of the week with the stubborn upper level pattern continuing to bring in a good fetch of monsoon moisture. Expect at least isolated PM showers and thunderstorms every day, but coverage should be more limited than the more potent monsoon surge over the weekend. PoPs remain generally in the 10 to 20% range each day of the upcoming work week. While the core of the upper level ridge will remain southeast of our area, expect a slow warming trend through the week, with highs generally around 5 degrees above seasonal averages. Southwest flow aloft will also support regular breezy to windy conditions in the typical areas of Carbon, Albany, and Converse counties, leading to continued elevated fire weather conditions.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1122 PM MDT Fri Aug 28 2026

Overnight, across all terminals, expect drier conditions with winds easing a bit to generally less than 10 knots except for KLAR where it may stay a bit breezier. Then, looking ahead to Saturday afternoon/evening, rounds of showers and thunderstorms are possible, impacting most of the terminals. This activity may linger into the overnight hours. Therefore, introduced a new round of PROB30 groups to account for this. Winds will ramp back up at all terminals by Saturday morning with gusts of 20 to 35 knots in Wyoming and 20 to 25 knots in the Nebraska Panhandle.

CYS WATCHES/WARNINGS/ADVISORIES

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