textproduct: Cheyenne

KEY MESSAGES

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

- 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 FRIDAY/

Issued at 302 AM MDT Wed Apr 1 2026

An active period of weather is expected today through at least Friday evening as multiple upper-level system push through the Intermountain West. Starting with today, southwesterly flow aloft is expected to turn southerly through the morning and early afternoon hours as an upper-level, negatively tilted, shortwave lifts northeast from southern Utah into northeastern Colorado then western Nebraska. This system is expected to have a strong, westward stacking with height, helping the system as a whole increase in strength as it moves across the CONUS. Multiple lobes of 500mb vorticity will eject out ahead of the incoming trough, leading to favorable differential cyclonic vorticity advection and synoptic lift throughout much of the atmosphere, especially with the CWA near the exit of the trough where rising motion is favored. Southwesterly flow at 700mb is expected to continue through the late mornings hours before more westerly flow develops as a 700mb low attempts to develop with the approaching system. A closed system at 700mb is progged to develop by 00Z Thursday in most models, further showcasing the increasing strength of this system. A stout Colorado Low will develop off the Rocky Mountains in eastern Colorado this afternoon and evening, leading to northwesterly flow across areas east of the Laramie Range and colder air funneling down into the region. Mountain precipitation has already begun across the Sierra Madre and Snowy Ranges, but precipitation chances spread northeastward through the late morning and early afternoon hours. Precipitation is anticipated to start as rain across much of the area as 700mb temperatures remain too warm for snow. Hires guidance suggests meager CAPE across western portions of the region, increasing confidence in an isolated thunderstorm or two this afternoon with the strong dynamics at play. With this in mind, beneficial precipitation is anticipated for much of the region, though some models remain a touch high on forecast QPF. However, NAEFS Mean Precipitable Water is above the 99th percentile this afternoon, so good moisture is anticipated with this system. Most locations will likely see anywhere between a 0.05 and 0.50in of precipitation this afternoon, with the higher amounts likely occurring under any thunderstorms that develop. Overcast skies will remain today with temperatures likely warming into the low- to mid- 50s east of the Laramie Range and upper-40s to low-50s west. Winter Weather Advisories remain in effect for the Sierra Madre and Snowy ranges where 5 to 10 inches of additional snowfall is anticipated through this evening.

A brief lull in precipitation is expected early Thursday morning through the afternoon hours before precipitation chances start increasing west to east. Upper-level flow will remain largely zonal throughout the morning hours Thursday before the next upper-level trough starts to move into the Intermountain West and upper-level flow turns southwesterly once more. The closed, 500mb system starts to move into western Wyoming by Thursday evening, with much of the western portions of the CWA under strong, southwesterly flow and within the left exit region of the trough, favoring synoptic lift across the region. Another 700mb system is progged to develop late Thursday night into the early morning hours Friday, leading to increasing height gradients and strong, southwesterly flow across western portions of the CWA and strong, westerly flow across the Laramie Range. As this system strengthens overnight, the 700mb jet will increase to 50 to 55kts across the CWA, leading to increasing concerns for high winds late Thursday through Friday. A second Colorado Low is progged to push off the Rocky Mountains early Thursday afternoon and deepen rapidly, leading to cold air once again funneling into the region and increasing surface pressure gradients and precipitation chances. A very strong cold front is anticipated to develop with this low, leading to rapidly falling temperatures Thursday evening into the overnight hours as 700mb temperatures cool rapidly to the -12 to -10C range by early Friday morning.

With this very strong cold front, a Bora High Wind Event is becoming increasingly likely across much of the area, with western portions of the CWA likely seeing high winds earlier in the day as the stout southwesterly flow dominates the area. High Wind Watches have been issued for portions of the CWA along I-80 and I-25 from Thursday morning (for western zones) through Friday evening. Eastern zones will not see high winds starting until Thursday evening into the overnight hours as the Bora sets up with maxed out downward omega values along the Laramie Range. As for precipitation on Thursday and Friday, the mountains will likely see primarily snow as temperatures remain cold enough for snow, rather than rain. However, lower elevations will see rain rapidly transitioning to snow west to east as the cold air moves into the region. However, the best QPF looks to remain west of the Laramie Range, where forcing is better. However, locations east of the Laramie Range will likely see another 0.01 to 0.10in of precipitation. The only location expected to see more precipitation than this is the area near the Pine Ridge, where northerly surface flow is expected to persist through much of the event, leading to several hours of upslope flow increasing precipitation amounts.

LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/

Issued at 302 AM MDT Wed Apr 1 2026

The upper-level trough slowly drags across the region Friday, with the trough not leaving the region until early Saturday morning. Strong 500mb vorticity will move through as the center of the 500mb low advects across the CWA. Very strong anticyclonic vorticity advection develops behind the 500mb low, leading sinking motion on the back side of the system and precipitation chances quickly tapering off. The 700mb low will strengthen rapidly Friday afternoon across central South Dakota, leading to a strong, northwesterly, 700mb jet across the Laramie Range as the strong cold front drags across the CWA. Downward omega values are expected to peak early Friday morning as the front pushes through, leading to the initial Bora event. However, as the 700mb low strengthens as it moves off to the east, a strong 700mb jet is expected to remain across the region, favoring high winds to continue through the afternoon and evening hours.

Dry, northwesterly flow returns to the region for Saturday as an upper-level ridge builds over the western CONUS once again. This will signal an end to the more active weather period as warmer temperatures and drier conditions return. Clear skies are expected this weekend with temperatures warming into the 40s and 50s on Saturday. Sunday will be beautiful, as skies remain clear and temperatures warm into the upper-50s west of the Laramie Range to the low-60s to low-70s east of the Laramie Range. Winds will remain mostly light on Sunday, further favoring a gorgeous end to the weekend. With the warmer and drier conditions returning, fire weather concerns start to creep back in Sunday afternoon as afternoon relative humidities drop back towards 15-20%. Another week of fire concerns is expected as afternoon humidites remain quite low for Monday, Tuesday, and Wednesday.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1133 AM MDT Wed Apr 1 2026

Lower ceilings and showers will move through all terminals this afternoon and early evening. Expect showers and possibly some thunder at LAR, CYS and RWL in the 21-0z timeframe. Thunder chances will be lower at the NE terminals however a period of light to moderate rainfall is likely at SNY and possibly AIA from 01z through 06z. MVFR ceilings will lower to potential IFR ceilings overnight during and after rainfall. Expect IFR ceilings to break after sunrise in the NE terminals on Thursday.

CYS WATCHES/WARNINGS/ADVISORIES

WY...High Wind Watch from Thursday evening through Friday afternoon for WYZ106. High Wind Watch from Thursday morning through Thursday afternoon for WYZ109. High Wind Watch from Thursday morning through Friday afternoon for WYZ110. Winter Weather Advisory until 9 PM MDT this evening for WYZ112- 114. High Wind Watch from Thursday morning through Friday evening for WYZ116-117. High Wind Watch from Thursday evening through Friday afternoon for WYZ118. NE...None.