textproduct: Cheyenne

KEY MESSAGES

- Afternoon and evening storms, some of which may become strong to severe, will be possible Saturday and again early next week along and east of I-25.

- Sunday will be the driest day as an upper level ridge builds over the area.

- Hot temperatures expected Sunday and Monday, with highs topping out in the mid 80s to mid 90s.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 225 AM MDT Sat Jul 4 2026

Pretty quiet weather this morning as all of the thunderstorm activity has moved well south and east of the forecast area, leaving mostly clear skies over the region. Otherwise, a typical July weather pattern will continue over the Front Range as a ridge of pressure aloft gradually intensifies over the next 60 hours. Weak winds will continue along with 700mb temperatures climbing above 15c by Sunday afternoon. Pleasant Independence Day today with highs in the 80s to low 90s. Models, including high res CAM guidance, showing a lower coverage of showers and thunderstorms today compared to what was previously expected. Although SPC hangs onto the Slight Risk for severe thunderstorms along and east of the I-25 corridor, high res guidance shows most of this activity further south along I-80 and mostly into Colorado and central Nebraska. This is because models have initialized the upper level shortwave further south and east...now showing it exiting the region as early as 3 PM this afternoon. Not completely comfortable lowering POP and Prob thunder below 25 percent quite yet with some activity expected from around Cheyenne to Sidney, and another potential cluster of thunderstorms forming along the Pine Ridge of the northern Nebraska panhandle and quickly moving southeast into Box Butte and Morrill counties between 3 PM and 5 PM. Any of these thunderstorms may contain large hail and/or strong gusty winds. Model soundings still show MLCAPE and SBCAPE around 1000 to 1500 j/kg, which is a little lower compared to yesterday but sufficient to produce significant convection with 0-6 km shear around 30 knots. The other question is the westward extent of the convection. Current observations along the I-25 corridor show the lack of return flow from the Great Plains with dewpoints stuck in the low to mid 30s for portions of the I-25 corridor and the Laramie Range. Will keep and eye on this trend and may need to lower the coverage of thunderstorms and/or limit the severe wording in this area. Thankfully, it looks like the bulk of the activity will be moving southeast out of the area by 6 PM this evening (may change depending on outflow boundary interactions). Lowered POP and prob thunder this evening as a result.

Sunday looks much quieter as a strong upper level ridge axis develops over the Front Range. 700mb temperatures are forecast to respond with values between 14c to 19c across the region, warmest over central Wyoming. Therefore, expect even Rawlins and Laramie to see highs in the mid to possibly upper 80s Sunday afternoon. With dry air aloft mixing down to the surface as a result of increasing midlevel subsidence associated with the upper level ridge, expect daytime convection to struggle to develop. High res models show some activity trying to get going around the Laramie Range and the northern part of the Cheyenne Ridge over towards Banner county and southern Platte/Goshen, but all high res CAMs show the activity quickly dissipating. In addition, shear is expected to decrease with only 10 to 15 knots in the afternoon. Lowered POP below 15 percent with only a few single cell thunderstorms possible, but unlikely at this time.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 121 PM MDT Fri Jul 3 2026

Monday...Similar synoptic pattern to Sunday, with enough mid level moisture to produce isolated to widely scattered afternoon and evening thunderstorms, primarily east of I-25 where convergence at low levels will be maximized.

Tuesday...Beneficial rain appears increasingly likely as low and mid level moisture increases markedly, while a shortwave trough aloft, also known as an atmospheric perturbation, moves overhead near peak heating, sparking scattered showers and thunderstorms, especially east of a Douglas to Laramie line, with isolated convection further west in the drier airmass.

Wednesday...Shortwave ridging builds aloft and with decreasing atmospheric moisture in the low and mid levels, expect a corresponding decrease in areal coverage of showers and thunderstorms.

Thursday...Expect a slight increase in afternoon and evening shower and thunderstorm coverage, as a shortwave trough aloft passes overhead near peak heating, though coverage will be limited and scattered due to warm temperatures aloft producing some convective inhibition, also known as CIN.

Friday...GFS showing a decent discontinuity in PWAT, precipitable water values, and low and mid level moisture from dry punch across southeast Wyoming, to a buoyant and moist atmosphere across western Nebraska. Since it is still day seven, our relatively low POPS for our eastern counties looks decent for now, though later shifts may see chances for thunderstorms, particularly across western Nebraska increase for the afternoon and evening.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 545 AM MDT Sat Jul 4 2026

Upper level disturbance is forecast to slide southeast across the high plains by mid afternoon, resulting in an isolated to widely scattered coverage of thunderstorms. Gusty winds and brief heavy rainfall possible.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail today and tonight with relatively light winds. Models have trended towards lower coverage of thunderstorm activity today compared to 24 hours ago with activity moving out of the area earlier in the evening. Kept PROB30 groups for KCYS, KBFF, and KSNY between 20z and 00z which have the best chance of thunder and rain showers this afternoon.

CYS WATCHES/WARNINGS/ADVISORIES

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