textproduct: Cheyenne

KEY MESSAGES

- An unsettled weather pattern will continue into the weekend with daily chances for afternoon/evening showers and thunderstorms.

- Strong to severe thunderstorms could be possible Friday and Saturday. Storms could contain damaging winds and large hail.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 427 AM MDT Fri May 29 2026

Low clouds remain over the majority of the forecast area this morning as the surface and low level moisture gets trapped under a transient ridge. This ridge is expected to push east as a negatively tilted trough begins pushing into the Intermountain West this afternoon. This push will provide the synoptic forcing to develop some showers with some embedded thunderstorms possible on the eastern side of our southeastern corner of Wyoming. Hi-res guidance places about 1800 joules of CAPE near the Wyoming and Nebraska Border this late afternoon. NAEFS still places PWAT values in the 90th percentile between 0.75 and 1 inch values along the same area. While there will be ample forcing for storm initiation the lack of shear will prevent most thunderstorms from being able to sustain themselves and eventually collapse one themselves. Most Hi-Res guidance does throw out the idea of potential pockets of 30 knot shear that could sustain a weak thunderstorm but the vast environment lacks the shear needed by thunderstorms to separate the updraft and downdraft region and survive. This now pulsy environment will have thunderstorms quickly pulse up and then collapse on itself leading to a very microburst-y environment. As these storms collapse it wouldn't surprise me if we start seeing brief strong wind gusts (microburst) underneath these collapsing cells. Saturday, looks to be a little drier as the upper level low begins to pivot and lift northward making us become rather dry slotted for most of the area. SPC has drawn a slight risk for the eastern edge of our portion of the Panhandle. Hi-res guidance paints a swath of 2,000 joules with favorable lapse rates and forcing to initiate convection. However, due to the proximity of the most favorable environment it is likely that storms may develop on our side of the Nebraska Panhandle and quickly push into South Dakota or into the more eastern Panhandle outside our jurisdiction. So it will be interesting to see how the dynamics come into play with the Low essentially pivoting over us and dryslotting our area on one half and eject strong streams of vorticity to increase forcing on the other. As this upper level low pivots and begins to lift northward, our pressure gradient begins to tighten and switches us to westerly flow. 700mb pressure gradients fields on the GFS and some hi-res models show a short-lived jet between 55 to 60kts develop overnight Saturday into Sunday. With the strong subsident flow of the dry slot those brief faster winds should easily mix to the ground to give us potential high winds between 03z and 09z Sunday with strong winds slowly dieing down throughout the afternoon Sunday the further the system lifts northward. Looking at the model omega fields, strong subsident flow remains over Bordeaux starting Saturday night and remains over it through Sunday afternoon increasing confidence in the strong gusty wind outcome. However, it's a little uncertain if the jet will remain strong enough to give us those high winds results or if we just end up getting close. This uncertainty in reaching high wind criteria has resulted in no headlines being issued on this shift and passed the torch to the day crew for one last look.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 427 AM MDT Fri May 29 2026

On Sunday, the flow becomes more zonal and 500 mb heights begin to rise as weak ridging builds in across our region, also yielding a drop in PWAT. Values remain around the 45th percentile across our area per ensemble guidance, so expect to see a drop in shower and storm coverage, with an activity being confined primarily to the Snowy and Sierra Madre Ranges. Thanks to rising heights and zonal flow, Sunday will be breezy with highs near or slightly above normal (average high for Cheyenne on May 31 is 71 degrees). Monday will be similar to Sunday, with a slight decrease in the winds and mostly dry conditions. Heading into the middle of the work week, the mid-level ridge begins to build across the Rocky Mountain West resulting in a gradual warming trend and mostly dry conditions, with no meaningful and widespread precipitation in the extended. Ensembles are hinting at an increase in in low-level moisture as well as PWAT mainly for our Nebraska counties (nearing the 85th percentile), however these details will need to be sorted out in future updates.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 546 AM MDT Fri May 29 2026

Some low level moisture is trapped under a weak area of high pressure resulting in IFR conditions for majority of the terminals in Nebraska. However there is an upper level low that will start to push in this morning effectively clearing the low level clouds and replacing them with higher level clouds for VFR ceiling heights. This upper level low will also develop some gusty showers this afternoon for the Wyoming terminals as well as some possible thunderstorms for our Nebraska side. Storm activity should subside after 00z for our Wyoming airports and around 06z for our Nebraska airports.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Dense Fog Advisory until 9 AM MDT this morning for WYZ116>118. NE...None.