textproduct: Cheyenne

KEY MESSAGES

- Slight Risk of severe thunderstorms this afternoon and Thursday with heavy rainfall, hail, and strong gusty winds possible.

- A ridge builds into the long term, drying the area out and developing Red Flag and potential heat advisory conditions through next week.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 125 PM MDT Wed Jul 8 2026

As of this afternoon the dryline is noted on radar right around the I-25 corridor and retreating westwards into Cheyenne proper. Development has begun along this boundary with a few storms noted, but nothing strong currently. Forecast sounding profiles across the region note inverted V's, which combined with DCAPE values into the 1000-1500 J/kg range would be indicative of high based storms with strong wind gusts the primary hazards. That being said, there is a little bit of instability across the region, and some meager support for updrafts, so we can't rule out a storm or two to have at least some hail, whether it be severe in size or small accumulating hail. Finally, moisture is actually notably plentiful east of I-25 despite the dry surface, with PWAT values into the 1-1.5" range. With the scattered nature of storm development, if any we get multiple stronger storms training over the same location, a marginal risk of excessive rainfall will be possible. Storms will continue into the early evening, but by around 8-9 PM storms should be on the decline as support wanes.

Moving into Thursday, our severe risk continues once again along and east of the I-25 corridor, but this time profiles will support a bit more organization to storm development. Initial storms should go up during the early afternoon with steep mid- level lapse rates and modest instability around 1000-2000 J/kg, which would support isolated storms capable of both large hail and damaging winds. This batch of activity though will likely grow upscale into a more linear feature, which will shift the primary hazard into mostly strong winds as storms evolve into western Nebraska. And like today, PWAT values into the 1-1.5" range should fuel at least a meager risk of localized flooding. Once again as the sun goes down we'll see storm activity wane and/or move out of our area.

LONG TERM /FRIDAY THROUGH WEDNESDAY/

Issued at 125 PM MDT Wed Jul 8 2026

Friday...The atmosphere dries out somewhat compared to today and Thursday, with shortwave ridging aloft bulging over eastern Wyoming. The 12Z GFS indicates decent low and mid level moisture for far southeast Wyoming and the Nebraska Panhandle, and diurnal heating and low level mechanical lift, along with a passing perturbation, will likely produce isolated late day showers and thunderstorms from I-25 eastward, and we may see our POPS and thunderstorm coverage increase somewhat in the next few model runs and days.

Saturday through Wednesday...Ridging aloft dominates our region, with quite dry air at low and mid levels, accompanied by 700 mb temperatures from 14 to 21 Celsius, thus chances for late day showers and thunderstorms will be nearly nil and non existent, and dry weather will prevail. The 700 mb temperatures will yield maximum temperatures in the 90 to 105 degree range. A weak perturbation and a slight increase in mid level moisture may spark isolated thunderstorms on Tuesday, and moreso on Wednesday, along the convective inhibition aloft gradient along the I-25 corridor and further to the west.

AVIATION /00Z TAFS THROUGH 00Z FRIDAY/

Issued at 547 PM MDT Wed Jul 8 2026

A relatively active evening for thunderstorm development is expected today, as the Storm Prediction Center in Norman, Oklahoma has a slight risk for severe thunderstorms through this evening, to the east of a Casper to Cheyenne line, including far southeast Wyoming and the Nebraska Panhandle. A marginal risk of severe thunderstorms for this evening exists elsewhere to the west of the aforementioned Casper to Cheyenne line.

Synoptically, a negatively tilted shortwave trough aloft will move into western Nebraska this evening, while a low level convergence axis develops along the Interstate 25 corridor, then storms will develop and strengthen as they develop and propagate across far southeast Wyoming, and especially the Nebraska Panhandle this evening, where scattered thunderstorms will likely conglomerate and develop into a Mesoscale Convective Complex, or MCC, somewhere over the Nebraska Panhandle this evening, thunderstorms will likely end across the Nebraska Panhandle in the 03Z to 05Z timeframe.

Wyoming TAFS...Using the 21Z HRRR, which has consistently been fairly accurate with respect to timing, high confidence, and expect thunderstorms to continue until around 02Z.

Expect TEMPO for thunderstorms at Rawlins, Laramie and Cheyenne for much of the early evening hours, and some storms will produce low level turbulence, strong downdrafts, as well as gusty and erratic winds up to 45 knots, along with brief MVFR visibility restrictions. VFR prevails however, with clouds clearing out late this evening and overnight. As is typical, expect gusty gradient and mix down winds until sunset.

At Cheyenne, best chance for thunderstorms, and high confidence, according to the likely accurate 21Z run of the HRRR, will be until 02Z, and storms increasing in coverage and intensity through early evening. Some storms will produce low level turbulence, strong downdrafts, as well as gusty and erratic winds up near 50 knots, along with brief MVFR visibility restrictions. VFR prevails however, with clouds clearing out late this evening and overnight. As is typical, expect gusty gradient and mix down winds until sunset.

Nebraska TAFS...High confidence in the 21Z HRRR run, which has consistently shown thunderstorms developing and/or propagating along the Wyoming and Nebraska state line around 23Z, and crossing the Panhandle during the 00Z to 04Z time frame, with clusters of thunderstorms and a possible MCC, Mesoscale Convective Complex, forming this evening, somewhere over the northern or central Nebraska Panhandle and propagating southeastward. The strongest storms will be capable of producing one inch diameter hail or larger, wind gusts in excess of 60 mph and locally heavy rainfall, along with low level turbulence, and strong downdrafts. Brief MVFR will be likely during the thunderstorms this evening, with skies clearing out late this evening and late tonight. As is typical, expect gusty gradient winds and mix down winds until sunset.

CYS WATCHES/WARNINGS/ADVISORIES

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