textproduct: Cheyenne

KEY MESSAGES

- Cool and unsettled weather will remain in place through Wednesday night with several chances for rain showers.

- A nocturnal low-level jet is expected to bring strong, gusty southerly winds to the High Plains tonight into Wednesday morning.

- Accumulating snow is expected for the higher mountains above 9000 ft in elevation tonight through Wednesday evening.

- Numerous showers and isolated thunderstorms are expected Wednesday afternoon and evening. A brief period of strong winds may occur along Interstate 80 behind this activity.

- After a brief warmup Thursday, another strong cold front will sweep through the area and bring additional chances for rain, snow, and high winds Thursday afternoon into Friday.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 300 PM MDT Tue Mar 31 2026

Unsettled weather has finally returned to the area after nearly three weeks of record warmth and high fire danger. Cooler than average temperatures prevail along and east of the Laramie Range, but the cold front did not quite make it west of the mountains, so mild temperatures continue in Carbon and Albany counties. Shower activity has been quite limited so far. Even though we have ample moisture in place aloft, forcing is weak today. Elevated shower activity will increase in coverage this afternoon and evening, especially along the Laramie Range where low-level convergence will help force some activity. Minimal instability in place may allow for a few lightning strikes.

Overnight, we will begin to see a few changes as the next Pacific trough approaches from the west. Increasing moisture and westerly flow will initiate moist orographic lift in the mountains. Integrated water vapor transport values are near climatological maximums over Colorado, but southern Wyoming will be on the edge of the moisture plume with values around the 97.5 percentile. Expect mountain snowfall to kick up overnight and continue through Wednesday morning, before becoming more showery during the afternoon and early evening hours. Further east, the surface ridge axis will pass by our area. Meanwhile, the approaching trough will support rapidly falling surface pressure over central Wyoming, which will increase the reverse pressure gradient over the High Plains. South to southeast winds will increase this evening and continue into Wednesday morning. Widespread wind gusts of 35 to 50 mph can be expected, with a chance for a few gusts over 60 mph, mainly along the Pine Ridge. Confidence was too low in exceeding this threshold to issue any High Wind products, but this will need to be monitored through the evening.

This system continues to trend slower, such that now the window for the best low elevation precipitation does not begin until around midday Wednesday. The 700-mb low will become better defined over western Wyoming during the day tomorrow, which should help produce stronger isentropic lift over the High Plains. Forecast soundings show strong instability over the area, at least for this time of year, with SBCAPE around 500 to 1000 J/kg along and west of the Laramie Range. Lastly, we will have cyclonic vorticity advection aloft helping to support large-scale lift over the area. Expect numerous to widespread showers with isolated embedded thunderstorms to develop. By mid afternoon, models show the central Wyoming surface low falling apart, allowing the strengthening lee cyclone over central Colorado to take over. As surface pressure rises from west to east, this may provide a focus to organize shower activity into the early evening hours as the frontal boundary from the west becomes absorbed into the developing cyclone. We will also need to watch for another round of strong winds developing for 3 to 6 hours behind this front. Strong cyclogenesis is a good reason to lean on the higher end for wind speeds, so winds were adjusted to the NBM 90th percentile along the I-80 corridor Wednesday evening. In-house guidance depicts approximately a 20-30% probability for high winds during this time along I-80 in southeast Wyoming, but this will need to be monitored over the next few forecast cycles as well. Precipitation should come to an end around midnight Wednesday night.

LONG TERM /THURSDAY THROUGH TUESDAY/

Issued at 300 PM MDT Tue Mar 31 2026

The long term forecast remains on track with a potent upper-level trough coming ashore Thursday and quickly making its way eastward throughout the day. This trough will bring cooler temperatures and precipitation chances to the CWA for the end of the work week. By Thursday afternoon, the trough will enter western Wyoming, with precipitation creeping into Carbon and Albany Counties. The cold front associated with this trough will be rather strong, advecting much colder air into the region very quickly. While precipitation may start as rain Thursday afternoon, it may quickly change to snow with the frontal passage. This raises concerns for snow squall potential as there will be minor instability out west with blustery conditions from a strong MSLP gradient. A flash freeze behind the front is also in question depending how quickly temperatures drop and when precipitation arrives. Snow will likely continue into the overnight hours for areas west of the Laramie Range with some accumulation possible for the lower elevations. High winds may also develop late Thursday night/early Friday morning. With the leeside trough and a high pressure building in northwest Colorado, a strong MSLP gradient will develop over the western half of the CWA. Winds aloft will increase up to 55 kts over the wind prones with strong subsidence to bring these winds down to the surface. In-house guidance gives most of the wind prone and wind prone adjacent areas about a 50 percent of hitting high winds. The window for high winds will likely be brief, with winds starting to weaken by Friday afternoon.

Models have come into better agreement regarding the upper-level closed low associated with the trough. Both the GFS and ECMWF track the low across the northern border of the CWA, however the models differ on precipitation amounts and placement. The GFS is dryer, primarily because of the strong downsloping winds off the Laramie Range. Downsloping winds will help dry out the low and mid-levels, keeping precipitation out of most of most of the Interstate 25 corridor. As a result, the GFS keeps most of the precipitation in the northern zones of the CWA. The ECMWF erodes the downsloping winds fairly quickly, bringing wrap around moisture a bit farther south in the North Platte River Valley. However, it still keeps the Interstate 80 corridor east of Cheyenne rather dry. Regardless of which solution comes to fruition, both have much colder high temperatures on Friday behind the front. Highs will mainly be in the 30s and 40s. These colder temperatures mean precipitation could fall as snow, or at least a rain/snow mix. At this time, cannot rule out some lower elevation accumulations for areas east of the Laramie Range, but for now, the most confidence in accumulation remains in the high terrain.

Once the trough moves out of the region, a return to warmer and drier conditions can be expected as upper-level ridging takes its place. Cold air aloft will still be in place Saturday, so the return to above average temperatures will happen on Sunday with highs in the 50s and upper 60s. Warm and dry conditions will persist at least through mid next week.

AVIATION /00Z TAFS THROUGH 00Z THURSDAY/

Issued at 528 PM MDT Tue Mar 31 2026

Light shower activity is being noted on radar in the vicinity of KLAR currently. Winds are generally out of the south at 20-25 knots with gusts to 30 knots for the Southeastern Wyoming terminals. At the Nebraska Panhandle terminals winds are out of the south to southeast at 10-15 knots. Overcast conditions prevailing into the overnight hours. Ceilings will drop to around 3000 feet from west to east as an upper-level disturbance propagates east. In response the low- level winds will increase particularly for the Nebraska terminals with gusts to the 30s possible. Rain chances increase starting around 17z tomorrow at Wyoming terminals then spread east to Nebraska around 20z. Periods of moderate rain are likely with some prob 30 chance of thunderstorms in the afternoon. Expect ceilings and visibilities to drop to MVFR for terminals with the onset of rain and IFR during thunderstorms.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Winter Weather Advisory until 9 PM MDT Wednesday for WYZ112- 114. NE...None.