textproduct: Cheyenne

KEY MESSAGES

- Widespread showers and storms are expected over the next several days. Monsoon moisture will lead to heavy rain with the potential for flash flooding. Isolated severe storms will also be possible.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 220 AM MDT Tue Jul 21 2026

Lift from a cold front that moved across the area earlier has lead to continued shower and thunderstorm activity early this morning. Storms are not moving particularly fast, allowing some decent rainfall accumulations. Hi-Res guidance does suggest showers and storms dissipating around sunrise, with a small lull in activity before storms once again develop early in the afternoon. Moist south to southwest flow will drive ample monsoon moisture into the CWA throughout the day. PWATs will rise into the 90th percentile as a result. Vorticity maxes aloft will aid in sparking convection across the area. Hi-Res guidance has storms developing early in the afternoon off the high terrain, gradually pushing eastward through the afternoon and into the evening hours. Model soundings do show cloud layer winds to be on the slower side, meaning storms today will be slow moving. The combination of high PWATs and slow storms will lead to heavy rain and the potential for flash flooding. Cannot rule out an isolated severe thunderstorm or two as there are pockets of elevated instability across both southeast Wyoming and western Nebraska. Storms will become more numerous and widespread by the evening hours, but will start to weaken and decrease in coverage by midnight.

Wednesday will basically be a repeat of Tuesday, albeit with better parameters. PWATs will reach the 99th percentile with even slower cloud layer winds meaning an even greater potential for heavy rains and flash flooding. Instability will be higher, especially across the Nebraska panhandle meaning a better likelihood for severe thunderstorms. Hi-Res guidance shows greater coverage of storms across the area, with precipitation once again continuing well into Wednesday night.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 1229 PM MDT Mon Jul 20 2026

Thursday...More beneficial rains are anticipated as a decent positively tilted shortwave trough aloft passes overhead near peak heating, and with beaucoup...plenty of low and mid level moisture and decent upslope southeast winds advecting low level moisture northwestward, expect to see numerous to widespread showers with scattered thunderstorms in the afternoon and evening, focused once again along the I-25 corridor and near the mountains where orographics will coincide with the best 850/700 mb theta-e ridge axis.

Friday...Drier air at low and mid levels advects into our counties as the dominant ridge over Colorado and southern Wyoming reasserts itself. Thus dry and hotter.

Saturday through Monday...Isolated to scattered afternoon and evening thunderstorms expected, with areal coverage increasing each day due to increased mid level moisture. Fortunately, more beneficial rains expected concentrated south of a Rawlins to Scottsbluff line and over and near the Snowy, Sierra Madre and Laramie Ranges. Typical weak northwest flow aloft on the northeast periphery of the ridge aloft will aid in occasional passing shortwave troughs aloft near peak heating.

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1115 PM MDT Mon Jul 20 2026

Continued scattered shower activity is evident on regional radars. This activity is not widespread enough to warrant including as a group in TAFs and is expected to diminish as the night progresses. Winds are variable and light at most terminals, but KLAR and KSNY are gusting to 25 knots out of the east. No MVFR CIGs are expected through tomorrow afternoon. In the early afternoon hours showers and thunderstorms are expected to start near KRWL and spread in coverage eastward through the afternoon and evening. Based on current trends and confidence in coverage in model guidance, prob30 group were added/kept to southeast Wyoming terminals. These cover tomorrow afternoon through the end of the forecast period. Some of these storms could produce strong winds to 45 knots or greater, lightning, and heavy rain at terminals. Outside convection the prevailing winds are out of the southeast between 10 to 20 knots.

CYS WATCHES/WARNINGS/ADVISORIES

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