textproduct: Cheyenne

KEY MESSAGES

- Monsoon moisture will remain in place through the end of the week across the high plains. Heavy rainfall and localized flooding possible through Wednesday night.

- More heat returns this weekend through Monday, with some near record high temperatures possible along with drier conditions.

SHORT TERM /THROUGH THURSDAY NIGHT/

Issued at 145 AM MDT Wed Jul 29 2026

Observations and IR Satellite this morning shows relatively quiet conditions with remnant convection from Tuesday evening weakening and drifting south across Colorado at this hour. Dewpoints are still in the 60s, even over Cheyenne, Wheatland and Douglas (I-25 corridor)...with dewpoints in the mid to upper 50s even in Laramie. Very moist airmass expected to remain over the area today with southeast winds through the day. Can't rule out some low clouds and/or patchy fog with the I-80 Summit reporting some fog at this hour. Added some fog to the forecast, but with limited coverage since probabilities are still pretty low. PWATs will remain between 1.00 to 1.60 inches, highest across the western Nebraska Panhandle. Another day of scattered to numerous showers and thunderstorms are expected Wednesday and Wednesday evening across most of the area as MLCAPE ranges between 1500 to 2500 j/kg. Models continue to show a broad upper level trough and embedded shortwave lifting northeast across the area today. However, upper level ridge axis is expected to remain strong out ahead of this feature with pretty low midlevel flow and the 70kt jet stream lifting north of the forecast area. This will greatly limit 0-6km shear across the region, so strong to severe thunderstorms appear unlikely at this time. Still see some marginal shear for a few model sounding locations across east central Wyoming, so may see some marginally large hail and, most likely, brief gusty winds. Heavy rainfall is still expected, but not seeing the same signals in the high resolution model data as we saw yesterday. Only a few locations in Morrill and Cheyenne Counties saw heavy rainfall amounts over an inch, so not nearly as concerned as we were yesterday. Some nocturnal convection is expected to linger past midnight early Thursday morning, but activity should be more isolated after 10 PM Wednesday evening. Forecast high temperatures will be tricky further south along the I-80 corridor due to cloud cover, some fog, and early initiation of convection. Lowered high temperatures by a few degrees along the I-80 corridor with highs in the 80s to maybe low 90s further east. Further north, high temperatures will generally remain in the 90s with more sunshine.

For Thursday, models show the upper level ridge axis attempting to rebuild over Utah, western Colorado, and western Wyoming behind the Pacific trough. Some drier air should make it into central Wyoming with a slight increase in westerly winds. Further east, models tend to dry things out too fast under weak northwesterly flow, so kept a slight chance of showers and thunderstorms in the forecast through the evening hours. In addition, the GFS and Canadian do show a subtle shortwave diving southeast embedded in the northwest flow aloft. May be a strong to marginally severe thunderstorm or two across east central Wyoming and the northern Nebraska Panhandle Thursday afternoon and evening. Temperatures will begin to climb over the whole forecast area on Thursday, with highs in the upper 80s to middle 90s expected. Drier air will take it's time moving into the eastern plains with weak advection in the low to midlevels.

LONG TERM /FRIDAY THROUGH TUESDAY/

Issued at 201 PM MDT Tue Jul 28 2026

Friday...Monsoonal moisture plume stretches north to south across far eastern Wyoming and western Nebraska, and with a ridge runner shortwave trough aloft in northwest flow, we expect to see scattered showers and thunderstorms generally east of a Douglas to Cheyenne line.

Saturday and Sunday...Ridging prevails with a decrease in monsoonal moisture and warm temperatures aloft will produce enough CIN, Convective Inhibition, to prevent thunderstorm development. Hot temperatures return with the hottest day being Sunday, and with 700 mb temperatures from 20 to 23 Celsius, high temperatures will range from 95 to 105 degrees, with possible Heat Advisories needed east of I-25 on Sunday.

Monday and Tuesday...Broad troughing aloft develops across the northern Rockies with zonal flow over our counties. This will help produce somewhat cooler temperatures as 700 mb temperatures lower to 13 Celsius. There may be enough low and mid level moisture to produce isolated late day thunderstorms over and near the Laramie Valley and southern Laramie Range.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 550 AM MDT Wed Jul 29 2026

Patchy fog will dissipate shortly after sunrise early this morning for mainly the eastern high plains. Another round of showers and thunderstorms will develop over the mountains around 18z to 20z and push east across the plains and high valleys this afternoon through late this evening. Gusty winds and very heavy rainfall possible for most terminals.

HAZARDS/WEATHER TRENDS: For early this morning, KAIA and KSNY observing some low fog due to nearly saturated conditions and light southeast winds. Expect conditions to improve to VFR after 14z.

VFR will prevail at all terminals through the late morning and afternoon hours. Thunderstorms will develop over the mountains and impact KRWL, KLAR, and KCYS after 19z. These thunderstorms will then move into western Nebraska after 00z Thursday. Very heavy rainfall, gusty winds, and IFR conditions possible (15% to 30% chance) for most terminals, especially KCYS, KLAR, and KSNY until 03z Thursday. Kept VCTS for the higher probability of thunder into this evening.

CYS WATCHES/WARNINGS/ADVISORIES

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