textproduct: Cheyenne

KEY MESSAGES

- A messy pattern is anticipated today through much of the upcoming week, allowing for ongoing precipitation chances across the entire CWA. The best chance for precipitation will be Monday night, with widespread rain and snow showers.

- A Winter Weather Advisory has been issued for the Sierra Madre and Snowy Ranges from 6PM Saturday through 6AM Monday.

- The messy, upper-level pattern continues mid-week through at least Friday before weak riding returns for the weekend.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 237 PM MDT Mon Apr 27 2026

The Intermountain West is currently under some very brief and weak ridging ahead of the next shortwave pushing into the high plains. Some of the clouds have dissipated leading to a clearing along the central portion of the Southeast Wyoming and the majority of the southern half of the Nebraska Panhandle. The RAP model wants to place between 200-700 joules of CAPE in the mountains of Carbon and Albany county, however a mix of low-mid level clouds have kind of parked themselves over that region for much of the day. The area that would be most likely with the highest potential energy would be the area that have cleared out this morning to allow diurnal heating to make the area weakly unstable. There should be enough CAPE for rain showers to utilize the energy to create a very weak updraft separating the ice crystals in the cloud, polarize the shower, and produce some bolts of lightning much like yesterday. Some light showers have already begun to form in the mountains and these showers are expected to move Northeast from the Sierra Madre and Snowy mountain ranges. A fast moving trough will impact the region later tonight. Looking at low-level water vapor and surface observations there is a sufficient amount of moisture for the wave to lift. Some lobes of strong vorticity with modest warm air advection (WAA) should give us decent precipitation amounts into the overnight period. The Hi-res models generally put the highest accumulations in the Summit/Foothill area between Laramie and Cheyenne around midnight tonight. This correlates to the timing of the trough axis and strongest WAA pushing through our section of the Intermountain West. As the wave pushes through overnight, the showers should slowly push northeast with some areas experiencing the cold rain transition to a light snow overnight. Outside of the the mountain ranges, snow accumulations will generally range from a very light dusting to possibly 0.5inches. THere may be some very isolated areas that may see an inch of snow overnight but its very low confidence as the models start to disagree how the showers will evolve overnight due to different placement of enhanced precipitation past the foothills. For Wednesday, a weak shortwave ejects out of the parent low over the Hudson bay leading to a slight trough to dive through the Intermountain West. Most models aren't "excited" by this wave in any means but some short lived showers may be produced as there looks to be some vorticity to enhanced the synoptic lift. Most models have the showers dissipating by Wednesday afternoon with no to very little precipitation accumulations.

Temperatures this weak should be fairly consistent the first half of the work week as 700mb temperatures bounce between 1C and -3c through Wednesday afternoon. This should keep the daily high temperatures in the 40's and 50's with overnight temperatures in the 20's and 30's.

LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/

Issued at 237 PM MDT Mon Apr 27 2026

As we head into the long term period, unsettled conditions will continue as the 500mb pattern remains active. This in part is due to a robust upper-level low centered over Ontario giving us northwesterly flow with weak shortwaves dropping south into our CWA. This will keep chances of precipitation elevated Thursday into Friday morning. As we progress in this forecast period, the upper- level low drifts off to the east while ridging noses into our CWA from the west. This will put an end to the precipitation by Friday afternoon after an unsettled week. The aforementioned ridge will be the primary feature controlling conditions here locally heading into and through the weekend, keeping us dry. Keep in mind, there are some disagreement in the main global deterministic models (GFS and ECMWF) with the placement and strength of said ridge. Well, all good things will come to an end if you want more chances of precipitation. Starting off next week, even though there is some model spread, another active pattern will commence as another upper level low slides east across the Intermountain West to our doorstep possibly by Tuesday of next week. However, there is significant model spread which creates uncertainty, so over the next few days we will get a clearer picture.

Lets briefly talk about temperatures and winds, really nothing to write home about on either. So, the focus will be on temps and what they will do. Starting out the long term, 700mb temps remain cool but gradually increase by Saturday into the +2 to +4C range and a few degrees warmer on Sunday. This translates to highs on Thursday climbing into the lower 50s along and west of the I-25 corridor with mid-to-upper 50s to the east. As mentioned above, 700mb temps will increase gradually over the weekend and by Sunday highs will soar into the mid-to-upper 60s west of I-25 and 70s to the east, warmest across the Nebraska Panhandle. This wont last long as cooler temperatures will return as we head into early next week.

AVIATION /00Z TAFS THROUGH 00Z WEDNESDAY/

Issued at 553 PM MDT Mon Apr 27 2026

Complicated forecast associated with numerous shortwave troughs propagating across SE Wyoming and W Nebraska bringing a combination of precipitation, low ceilings, and decreased visibility. For the Wyoming terminals, expect IFR conditions after 02Z given visibilities of 2-3 SM and CIGS below 3 kft until 16Z once precipitation is expected to be to the east over Nebraska. Winds are expected to range from 5-10 knots.

For the Nebraska terminals, precipitation coverage is expected to increase after 06Z. CIGS will fall below 1 kft especially in the vicinity of any showers resulting in IFR conditions. Confidence in the precipitation coverage and timing is low and will ultimately depend on the when exactly the vorticity maximum ejects over our region. 5-10 knot winds will be variable in direction throughout the TAF period.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Winter Weather Advisory until 3 PM MDT Tuesday for WYZ112-114. NE...None.