textproduct: Cheyenne

KEY MESSAGES

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

- Near record high temperatures possible Monday afternoon, mainly across western Nebraska with highs around 90 degrees.

- 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 middle to late in the week.

SHORT TERM /THROUGH TUESDAY NIGHT/

Issued at 215 AM MDT Mon May 25 2026

Not much going on this morning with skies becoming mostly clear with relatively mild temperatures in the upper 40s to upper 50s. Winds are mostly light and variable with some breezy conditions observed in the wind prone areas, but gusts have remained below 40 MPH. Overall, another pleasant day setting up for this Memorial Day with highs in the 70s for Carbon and Albany counties, with readings in the 80s to around 90 for eastern Wyoming (east of I-25) and western Nebraska. A few locations will approach record high temperatures for the day over western Nebraska. Similar weather compared to Sunday with models showing another chance of widely scattered showers and isolated thunderstorms across the region. Activity will likely be more rain shower activity than thunderstorms due to the lack of forcing and the upper level ridge axis remaining over the area for the bulk of the day. Convective environment is pretty marginal as well with inverted V soundings for most areas. However, models indicate a shift in the weather pattern beginning later today as a deep upper level low digs south across the Pacific NW later in the day; meanwhile, a broad upper level disturbance will begin to lift northward near the Mexico and USA border. These two systems will be the primary drivers in our sensible weather for most of the week. Kept POP on the low side (15% to 25% outside the mountains) into this evening. Low level moisture will begin to increase this evening ahead of the upper level disturbance to our south with increasing south to southeast winds and low to midlevel moisture advection.

For Tuesday, all models show the upper level disturbance to our south continuing to lift north as the upper level low along the Pacific coastline digs south into the western Great Basin region. Should see the beginning of higher coverage of showers and thunderstorms for the week, but should be mainly confined along and west of the I-25 corridor at first where the best forcing will be located. High res models are showing several bands of heavy showers and thunderstorms lifting north across southeast Wyoming with little or no activity for most of western Nebraska. Kept POP highest ahead of the upper level disturbance and where NAEFS continues to show PWAT over the 90 to 95 percentile for this time of the year. Although the risk is low, there is some concern of heavy rain over the mountain snowpack from the last few late-season winter storms...especially on the lee-side of the Sierra Madre and Snowy Range. Mountain snowpack is on the low-side for this time of the year, so confidence is limited. Otherwise, some of these thunderstorms may become strong with hail and strong gusty winds the main threats. Not expecting severe weather at this time due little or no shear where CAPE>500 j/kg (east of I-25). There is quite a bit of speed shear (30 to 45 knots) across Carbon and Albany counties, but CAPE is not expected to be optimal with activity initiating too quickly/too often in the late morning and afternoon hours. Will continue to keep an eye on this in the event conditions change. Showers and thunderstorms will likely continue into the late evening hours towards the Nebraska border Tuesday night. Remaining warm on Tuesday, but noticeably cooler west of the Laramie Range with highs in the upper 60s to around 70.

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 /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 550 AM MDT Mon May 25 2026

An upper level ridge axis will remain of the area before lifting northeast later this afternoon and into tonight. Widely scattered showers and isolated thunder possible this afternoon and into this evening for most terminals.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail over the next 24 hours. Kept a mention of thunderstorms for the terminals with the best potential to see some activity between 20z this afternoon and 02z Tuesday. With the pretty isolated nature of the tstorms, kept PROB30 groups. Gusty winds up to 40 knots are possibly with any showers or thunderstorms that do develop. Reduced VIS looks unlikely at this time with a pretty dry boundary layer.

CYS WATCHES/WARNINGS/ADVISORIES

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