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.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 145 PM MDT Sat May 23 2026

We are enjoying a pleasant day across the region today as we transition from the cool and unsettled weather pattern that has dominate the last several days into a warmer pattern that will prevail for the next several. Aloft, the broad trough is moving out as apparent on GOES satellite imagery, and ridging is starting to build in over the western CONUS. A very disorganized series of vort- maxes continues to progress through the area, providing some very weak ascent in place of minimal instability. SBCAPE ranges from about 100 to about 500 J/kg across the area, with the higher values present further east. This will support a few widely scattered high- based showers, which are already showing up on radar and satellite, continuing through the early evening. Expect a few rumbles of thunder and gusty and erratic winds near this activity, but rainfall will be minimal.

Ridging will start to take over on Sunday, pushing high temperatures above 10 degrees above today's values. A jumbled mess of 500-mb vorticity will push in from the west during the afternoon hours. At the same time, a weak tap of Pacific moisture will allow mid to upper level moisture to begin to recover. This will lead to another round of high based showers and thunderstorms, with overall coverage expected to be greater than today. Rainfall will also be more likely to reach the ground Sunday with the higher moisture content aloft. This activity will be concentrated further westward, beginning in Carbon county in the early afternoon and spreading eastward later in the afternoon and through the evening. This activity will start to run out of steam heading east of the I-25 corridor, but expect a few isolated showers with some rumbles of thunder to survive. With the vorticity aloft maintaining forcing into the evening, we could see a few evening heat bursts after the surface decouples from the deep, mixed boundary layer just above.

Monday will be the warmest day of the period to round out the holiday weekend. The ridge axis will shift east of our area and amplify significantly as a strong upper level low begins to dive into the Pacific northwest. Another more subtle upper level low over the desert southwest states will set up southerly flow aloft and initiate a pseudo-monsoonal pattern for a day or two. Expect another round of scattered afternoon and evening showers and thunderstorms Monday. NBM PoPs remain consistently too low for all three days of the holiday weekend, but slight chance (20%) PoPs from the previous forecast were maintained and slightly expanded between 18z and 06z each day. In addition, Monday will bring a chance for record highs. Highs will be at or above the climatological 90th percentile across the area, but the greatest chance for records is in the Nebraska panhandle, where forecast highs are generally within 1-3 degrees of the daily record.

LONG TERM /TUESDAY THROUGH FRIDAY/

Issued at 145 PM MDT Sat May 23 2026

The global models continue the trend of a deep reinforced trough from the Low over the Alaskan Bay and pushing into the Pacific Northwest. This will still push us into a southwest advecting in some moisture from the Pacific on Tuesday. By Tuesday afternoon the low pressure system gets close enough to send a shortwave as a catalyst to another wet pattern. Thanks to our summer sun, the synoptic set up of this deep trough will lead to decent destabilization of the atmosphere and produce scattered thunderstorms for the afternoon and evening. This bowling ball of a low gets temporarily cut off from the synoptic as an omega block begins to setup over the CONUS region. An area of high pressure appears to sit over the Northern Plains region while Lows sit and spin over the Nova Scotia region and the West coast. While the low from the West coast parks itself over Nevada it will send with corresponding shortwaves through the intermountain west for almost daily chances for showers and thunderstorms to finish out the month of May. The global models still show a sort of a wet start to June but the models have diverged on the details. But any moisture to have put a dent in the drought is more than welcome for Southeast Wyoming and the Nebraska Panhandle.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1132 AM MDT Sat May 23 2026

A cumulus field is already starting to develop with some light showers just to east of KCDR. Isolated to scattered showers are expected this afternoon but with our westerly flow no precipitation is really expected to hit the ground. There is an isolated chance for a couple bolts of lightning with some rumbles of thunder but for the main part these are going to be more your afternoon garden variety showers. A pocket of high pressure does look to move through our area where the winds will become light and variable at times overnight.

CYS WATCHES/WARNINGS/ADVISORIES

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