textproduct: Cheyenne

KEY MESSAGES

- Widely scattered showers and isolated thunderstorms in the afternoon and evening will bring the potential for localized strong, gusty winds for both Sunday and Monday.

- Near record high temperatures will continue through Tuesday.

- A stormier weather pattern will setup on Tuesday and continue through the remainder of the week with daily chances for PM showers and thunderstorms.

- Increasing potential for strong to severe thunderstorms is being monitored for Wednesday through Friday.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 130 PM MDT Sun May 24 2026

Summer weather is back across the area today as upper level troughing that has dominated most of the last week is replaced by a modest ridge. While temperatures have warmed to values about 10 degrees above average today, this is not a very clean ridge. A jumbled mess of 500-mb vorticity continues to translate over the central and northern Rockies on top of the ridge aloft. While the boundary layer remains quite dry this afternoon, moisture aloft is beginning to increase as Pacific moisture is advected inland from the west. Cloud cover will increase from west to east this afternoon and evening. Weak synoptic lift in place of modest instability (100 to 300 J/kg SBCAPE over the High Plains and 300 to 700 J/kg in Carbon and Albany counties) will also support increasing coverage of high based showers and isolated thunderstorms. Soundings across the area show a deep inverted-v, but ample moisture aloft should prevent today's activity from being completely dry. Brief downpours are more likely west of the Laramie Range. Further east, expect rainfall to be more limited as rain drops will need to travel through a much deeper and drier boundary layer. The primary hazard today will be dry microbursts (or dry-ish microbursts west of the Laramie range) thanks to the warm temperatures and dry boundary layer. DCAPE is already substantial, around 600 to 800 J/kg west of I-25 and 800 to 1200 J/kg east of I-25. These values may climb by a few hundred J/kg over the next few hours too. The axis of the very subtle upper level shortwave will not really move overhead until around midnight tonight. As a result, showers will probably continue well into the evening hours tonight. After sunset, the surface will decouple from the well-mixed boundary layers aloft, which may set the stage for a few heat bursts over the High Plains this evening. Most storms will produce wind gusts in the 40 to 55 mph, but a few gusts over 60 mph are certainly possible.

Monday will transition into a different weather pattern that will prevail for most of the week ahead. A powerful upper level closed low will begin to dive into the Pacific northwest on Monday, pushing the ridge aloft east of the area and into the central Plains. Southerly flow aloft will increase in between the two, pulling improved moisture northward in a pseudo-monsoonal pattern. The warmth will peak on Monday with NAEFS mean 700-mb temperatures around +10 to +12C across the area. Expect highs to range from the mid 70s in Laramie and Rawlins up to the lower 90s in the Nebraska panhandle. Nebraska locations will be within a few degrees of daily record highs. As moisture arrives from the south in the early afternoon hours, another round of widely scattered showers and isolated thunderstorms will kick up, bringing another chance for dry microburst activity. NBM PoPs remain too low over the High Plains as they have for the last several days, so slight chance (20%) PoPs were maintained from the previous forecast for Monday afternoon and evening.

While Monday will feature a very weak pressure gradient and thus light winds across the area, this will change heading into Tuesday. The powerful upper level trough will dive southward, taking on a negative tilt underneath a blocking ridge which will amplify over the northern Plains. Nearly vertically stacked, strong southerly flow will increase as pressure falls to the west, and rises to the east. Integrated Water Vapor transport values per the NAEFS mean are around the 90 to 97.5 percentile, pushing precipitable water over the climatological 90th percentile. Over the Plains, warm and breezy conditions will continue with highs a touch warmer than Monday north of the North Platte River, and a touch cooler to the south. While dewpoints will be improving with the southerly moisture fetch, the warm temperatures will keep RH fairly low. Further west, forecast soundings show near saturation throughout the column with ample moisture moving in. Another vort-max is expected to be pulled up from the south, moving into the area with peak-heating in the early afternoon hours. This will initiate widespread showers and isolated embedded thunderstorms (instability looks limited) over Carbon and Albany counties during the early afternoon hours, and continuing through the evening. This will spread east of I-25 in the late afternoon and evening, but coverage to the east will be much more limited.

LONG TERM /WEDNESDAY THROUGH SUNDAY/

Issued at 130 PM 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. Thursday into Friday, The spinning upper level low looks to eject a surface low to increase the amount of forcing on Friday. Each of the global models puts the area of the most unstable CAPE in a different area (which is to be expected) but given those values range between 1500 to 2500 Joules, Friday could be signaling a particularly explosive environment and with the right dynamics and spin all hazards could be possible at the end of the work week.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1738 PM MDT Sun May 24 2026

Some stronger showers are north of KLAR and near the CO/WY border near the Snowy Mountain Range. Otherwise not much rain has been hitting the ground so VCSH was used and any -TSRA or -RA was taken out of the TAFs. not quite sure if the showers will make it to the Nebraska Border as the showers are weakening and dissipating before reach KBFF. Will amend as needed but not to hopeful that any of the stronger showers will make it through the evening.

CYS WATCHES/WARNINGS/ADVISORIES

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