textproduct: Cheyenne

KEY MESSAGES

- A warming trend will carry through Memorial Day weekend, with near record high temperatures possible by Monday.

- Isolated high-based showers and storms will be possible each afternoon over the long weekend, but rainfall will be limited.

- Potential for thunderstorms and rainfall will increase Tuesday and continue through much of next week. Stronger storms possible on Wednesday.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 200 AM MDT Sun May 24 2026

Zonal flow aloft continues through the early evening hours today before southwesterly flow returns ahead of an incoming upper-level low off the southern coast of California. The southwesterly shift in the upper-level flow will open a gate of Pacific moisture to funnel into the CWA throughout much of the day Monday and into Tuesday as well. Ahead of the incoming trough, multiple lobes of 500mb vorticity will eject out and into the region, leading to synoptic ascent during the afternoon to early evening hours Sunday. 700mb flow suggests a few weak, subtle disturbances pushing through the flow, further supporting additional synoptic ascent into the afternoon and evening hours. Additionally, 700mb warm air advection will be abundant across the CWA, leading to increasing confidence in enough lift across the region to get a few isolated to scattered showers and storms this afternoon and evening. Hires guidance suggests isolated showers and storms mainly along and east of the Laramie Range. The biggest factor preventing showers and storm development today will be low-level moisture. Forecast RAP soundings suggests a pretty typical, strong Inverted-V signature with large DCAPE and minimal SBCAPE, likely only around 100-200 J/kg. Therefore, any shower that develops today will likely struggle to get rain to actually reach the surface, given the very dry low- levels. Additionally, 100-200 J/kg of SBCAPE is enough to get some lightning strikes across the area. With precipitation likely evaporating before reaching the ground, dry lightning is possible. Temperatures this afternoon will warm into the 70s and 80s, with clouds increasing from west to east throughout the day and into the overnight hours. Overnight lows will remain on the warmer side, due to the increasing cloud coverage, remaining in the 40s and 50s across the region.

Monday will be a transitional day as the upper-level trough evolves and moves into the southwestern CONUS. Southwesterly flow aloft will continue to funnel more Pacific moisture into the region, with strong southerlies develop across the Intermountain West as the day progresses. Multiple vorticity maxima will continue to eject out ahead of the re-organizing trough near the Four Corners Region, while 700mb warm air advection ramps up across the region. Therefore, another day of isolated to scattered showers and thunderstorms is expected across the region. Forecast RAP soundings once again suggests Inverted-V signatures everywhere, though MUCAPE and SBCAPE will be significantly higher on Monday, between 300 and 500 J/kg. While precipitation will not be favored to reach the ground with the dry surface-layer, if a strong enough storm is able to form, it could produce decent enough rainfall to get some reaching the surface. There is low confidence in this right now. One thing that is quite confident is that Monday will be hot. Temperatures west of the Laramie Range will rise into the mid-70s to low-80s, while temperatures soar into the low-80s to low-90s east of the Laramie Range, with the warmest temperatures across western Nebraska.

Stout southerly flow is expected by Tuesday morning as the upper- level trough over the Four Corners region starts to move northward before getting absorbed by the much stronger, and still strengthening, trough dropping south along the West Coast. With the turbulent upper-level pattern Tuesday morning into the afternoon hours, multiple vorticity maxima will eject out across the region, while the strongest vorticity remains within the strong trough along the West Coast. Fairly strong southerly 700mb flow will develop by Tuesday afternoon, pulling in additional moisture from the moisture rich regions of Texas and Oklahoma, with additional moisture from the broad southwesterly flow west of the Laramie Range. 700mb warm air advection will likely be at its peak on Tuesday afternoon with the very strong southerly flow across the region at that level. Therefore, stronger lift is anticipated across the region. With surface flow turning south-southeasterly Tuesday afternoon, the added easterly component will lead to some additional lift due to upslope flow along the eastern side of the Laramie Range and along the Cheyenne Ridge. Despite this, medium range models still suggest only about 200 to 500 J/kg of MUCAPE with pockets of 700 J/kg according to the NAM. So while strong forcing will be ongoing, the instability remains fairly low. Strong storms could be possible Tuesday afternoon, but gusty winds look to be the primary threat due to the Inverted-V forecast sounds, if a storm can get going. Isolated to scattered showers will also be possible, though wider coverage is expected west of the Laramie Range due to this region being closer to the upper-level support provided by the incoming trough. Wednesday looks to be the better day for strong thunderstorms. Tuesday will also be warm once again, with highs in the mid-70s to low-90s once more.

LONG TERM /WEDNESDAY THROUGH SATURDAY/

Issued at 200 AM MDT Sun May 24 2026

The upper-level low dropping south will continue its progression Wednesday, but starts to become cutoff from the flow mid-day Wednesday. The low looks to be cutoff over Nevada, with strong southerly flow across the CWA Wednesday through the rest of the week. This low will remain cutoff and spinning over Nevada until Friday when it gets absorbed back into the flow by the next incoming strong trough. However, with this cutoff low progged to spin over Nevada for several days, a very wet pattern is anticipated Wednesday onwards, due to continued synoptic ascent and support downstream of the churning upper-level low. This especially true with 700mb and surface flow remaining strongly southerly through Friday when a weak front tries to push through. With 700mb and surface flow remaining southerly, warm, moist air will continue to advect into the region leading to a warm week ahead that might event feel a touch muggy! With warm, moist air and synoptic ascent nearby, daily afternoon showers and storms will be possible, with Wednesday looking more favorable for stronger storms across the region. This cutoff low pattern looks to come to an end for next weekend, as cooler, more seasonable air starts to the return to the region ahead of the upper- level trough pushing through.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1115 PM MDT Sat May 23 2026

Some mid level cloud cover is passing through the area in association with a shortwave impulse, but should be parting around sunrise. Gusty winds at Nebraska Panhandle terminals is likely for the next few hours in response to air mass recovery from the storm complex that pass through the state yesterday evening. These winds will calm down and become variable by sunrise. Mostly clear skies at daybreak become increasingly cloudy as daytime convection forms. Winds out of the west at 15-25 kts are expected at all terminals in the afternoon hours. As showers and isolated thunderstorms mature there may be downburst potential at terminals. Some high resolution guidance are resolving wind gusts to 45 knots or higher from this activity. These showers or storms can pose a risk to aviation with strong and erratic winds. KRWL, KLAR, and KCYS have the greatest chances at being impacted by this activity through tomorrow evening. A cluster of these showers may persists late into the forecast period to impact Nebraska Panhandle terminals.

CYS WATCHES/WARNINGS/ADVISORIES

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