textproduct: Cheyenne

KEY MESSAGES

- A Slight Risk (2 of 5) of severe thunderstorms is possible Monday for eastern Wyoming and the Nebraska Panhandle, with all severe hazards possible.

- Expect a quick cool down on Monday before a quick warmup on Tuesday, and then temperatures moderate through the end of the week though still around 5 to 10 degrees above normal.

- Red Flag Warning in effect for the eastern high plains of southeast Wyoming and all of western Nebraska Tuesday through late Wednesday, with critical fire weather conditions likely extending through late in the week.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 1234 PM MDT Mon Jun 8 2026

Severe weather will once again be possible this afternoon for areas east of the Laramie Range. Model soundings show a favorable environment for all modes of severe weather with large hail, severe wind gusts and an isolated tornado all possible this afternoon and evening. Flash flooding also cannot be ruled out with high PWs over the Nebraska panhandle. Radar already shows a few storms over Albany County going up where a cumulus field developed. The uncapped environment here quickly led to the development of a few stronger updrafts with some small hail. As these storms progress eastward, they will enter a less favorable environment with less SBCAPE and shear, so they will likely weaken an fall apart. Mesoscale analysis as well as model soundings show a more favorable environment east of the Laramie Range around mid to late afternoon. Soundings from the GFS still indicate a strong capping inversion around 18Z that will first need to erode away. Hi-Res guidance like the HRRR also seems to be catching on to this, showing convection developing a little later in the day with each new run.

Once the cap erodes and convection can actually get going, the environment shows both good instability and shear. Model soundings show MUCAPE values up to 2000 J/kg of CAPE with about 45 kts of effective shear. These parameters along with steep mid-level lapse rates will support a large hail threat for areas east of the Laramie Range. Severe wind gusts will be a secondary threat in some of the stronger storms with DCAPE approaching 900 J/kg. Cannot rule out an isolated tornado or two as MLCAPE reaches about 1500 J/kg by this evening with the favorable shear. As previously mentioned, flash flooding could be possible with PWs around an inch in the Nebraska panhandle. Luckily, cloud layer winds are fairly fast so storms shouldn't sit in any one area for too long. While convection is already occurring and will continue for the next several hours, Hi-Res guidance has delayed the timing of severe storms, making the most likely window between about 6 PM and 10 PM this evening. Once storms move out later this evening, it will be a calm overnight.

Even though a strong trough will push into Wyoming on Tuesday, the weather will be a bit quieter compared to Monday. Ahead of the trough, southwest flow will dominate the low and mid-levels. Southwest flow will advect hot and dry desert air into the CWA. 700 mb temperatures will climb to about +14C which is roughly the 90th percentile of NAEFS climatology. This will lead to quite a hot day, mainly for areas east of the Laramie Range. High temperatures here will reach the upper 80s and 90s. These hot temperatures will help dry out the eastern portions of the CWA, with relative humidity dropping as low as the single digits. With the incoming trough, a 250 mb jet will move into the CWA creating windy conditions. This combination of dry and windy conditions will lead to fire weather conditions. As a result, the Fire Weather Watch in effect was upgraded to a Red Flag Warning. The trough could also trigger some shower and storm development across the CWA. Given the very dry low and mid-levels, gusty showers with severe wind gusts are possible. Dry lightning will also be possible, given a few hundred joules of elevated CAPE.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 1234 PM MDT Mon Jun 8 2026

The long term forecast appears dry with a switch in the flow regime from southerly flow to a more westerly. This is due to a persistent upper level trough pattern to our north into Canada. A cold front Wednesday will effectively cut us off from the more moist air that has been advecting in from the Gulf. During this period we are watching for conditions favorable for fire weather and high winds.

The high wind conditions spill over from Tuesday as flow at the 700 mb level stays elevated. The GFS is projecting winds at this level at around 50 knots. As daytime mixing commences the risk of these winds being mixed to the surface increases. Additionally enhancement by mountain wave breaking is likely to occur. Taking a horizontal cross section across our west to east ranges depict downsloping winds approaching 55 knots during the late morning to early afternoon hours collocated in areas of negative omega. Higher gusts are certainly possible given the low resolution of global models. This is not a great combination with the expected low relative humidities values. Across most of the area values are expected to plummet below 15 percent and temperatures in the 70s to high 80s. This is following previous poor nighttime recoveries of about 40-50 percent.

Going into Thursday and beyond, winds start to calm down after the departure of the mid level shortwave and ridging builds in. As mentioned our source of moisture has been cut off by the prevailing synoptic pattern, so humidity values remain very low. Winds are likely to remain high enough to warrant continued fire weather products through just about the entirety of the long term. Saturday and Sunday may see enough moisture and a source of lift from a clipper type system to support a few storms. Both GFS and Euro are on board with this solution with the usual caveat being that at this range solutions will change. If you are looking for any bit of good news past the long term, the latest CPC outlook has our area in below average temperatures and increased precipitation chances.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1131 AM MDT Mon Jun 8 2026

Scattered severe thunderstorms will be possible at terminals mainly east of the Laramie Range this afternoon and evening. Main concerns in storms will be severe winds with gusts over 50 kts and large hail. Moderate to heavy rain will also be possible, which could reduce visibility down to MVFR criteria at times. Storms will move out of the area before midnight. Cannot rule out some patchy low stratus and fog Tuesday morning from the moisture left behind from storms, however probabilities of this occurring are currently low.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning from noon Tuesday to 9 PM MDT Wednesday for WYZ430>433. NE...Red Flag Warning from noon Tuesday to 9 PM MDT Wednesday for NEZ434>437.