textproduct: Cheyenne

KEY MESSAGES

- Strong to Marginally Severe thunderstorms expected Tuesday through Thursday for most locations.

- Slight Risk of severe thunderstorms Wednesday afternoon and evening with very heavy rainfall, hail, and strong gusty winds possible.

- A ridge builds late in the long term, drying the area out and perhaps breaking heat records.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 255 AM MDT Tue Jul 7 2026

Surface observations across the region show relatively mild temperatures early this morning with readings in the upper 60s to upper 70s in a few spots, mainly over the western Nebraska panhandle. South to southeasterly winds continue to result in good low level moisture advection with dewpoints in the 50s for eastern Wyoming and western Nebraska. With decent low level moisture remaining over the region today...and similar convective parameters as yesterday (Monday), expect Tuesday to be nearly a carbon copy of yesterday with scattered showers and thunderstorms by mid to late afternoon. High resolution CAMs have been very consistent with this activity developing around noon across the mountains and pushing east across the plains. Slightly more favorable shear profiles and SBCAPE/MLCAPE values around 1500 j/kg/1000 j/kg respectively should result in more than just isolated strong to marginally severe thunderstorms. SPC has extended the Slight Risk area to include extreme east central Wyoming and the far northern Nebraska Panhandle this afternoon and this evening. Overall, it looks like the primary threat will be strong gusty winds, as it was yesterday. Marginally large hail (1.00 to 1.50 inch diameter) looks slightly more favorable today also, but should be very isolated due to the relatively weak shear...which really doesn't increase until later in the day. Thunderstorm and/or shower activity may actually linger well into the late evening hours and after midnight tonight since models now show another upper level shortwave axis moving into central Wyoming and eventually east across the high plains after midnight. Have to keep an eye on the convective environment as this feature tracks east later tonight. NAM and GFS soundings show elevated MUCAPE of 1000 to 1500 j/kg north of I-80. Confidence is very low at this time with all high res guidance showing weak and very isolated activity, so kept POP around 20 percent up until 3 AM Wednesday for now. High temperatures today may be a few degrees cooler compared to the last few days, but highs in the mid 80s to mid 90s are expected for a bulk of the area...with highs near the century mark across the northern and central Nebraska Panhandle.

For Wednesday, all models show the upper level ridge flattening as near-zonal flow develops over the forecast area. A potent and broad upper level shortwave is forecast to quickly push east- southeast across the plains. Expect Wednesday afternoon and evening to be the best chance so far for severe thunderstorms. Increasing midlevel unidirectional flow will result in nearly straight hodographs with plenty of speed shear. This set up tends to favor upscale growth and squall lines for most locations. A quick look at the model soundings show CAPE values increasing to 2000 to 3000 j/kg with PWATs near the 90th percentile. Could see some very heavy rain and strong gusty winds, with the potential for multiple bands of thunderstorms as the shortwave moves overhead. Not surprised to see SPC introduce a Slight Risk of severe thunderstorms to most of the high plains, including the I-25 corridor. This Slight Risk will favor strong gusty winds, but can't rule out some large hail in this environment also. Several places may see some good rainfall amounts in this set up (fingers crossed). Kept POP on the high side, between 50 to 70 percent across a large portion of the forecast area. Noticeably cooler with highs in the 80s, but cooling off rapidly with any nearby rainfall.

LONG TERM /THURSDAY THROUGH MONDAY/

Issued at 152 PM MDT Mon Jul 6 2026

Afternoon thunderstorms should be ongoing through the first couple of hours of Wednesday night. This activity should tapper off before midnight leaving for a cloud filled and muggy night. Some fog could be possible in portions of the Nebraska Panhandle.

Thursday will be the last day in a stretch for mild afternoon temperatures. The remainder of the monsoon moisture and upper level lifting will keep the weather interesting, something that cannot be said for later on. Afternoon highs are likely to stay below 90. We will need to watch the western most counties for elevated fire conditions. Minimum relative humidity values will bottom out in the mid to lower teens for portions of Carbon, Albany, and Converse Counties. Winds look to be just below red flag criteria at this time however. Afternoon thunderstorms are anticipated along I-25 where MUCAPE values of around 2000 J/kg and bulk wind shear of 30-40 knots could support some organized thunderstorms. The sub cloud layer may not be as dry as it has been during the previous days allowing for more rainfall from storms along with severe weather potential.

Past Thursday and through at least Monday the upper level ridge builds with force and subsiding air starts drying and heating the area. A large portion of the Nebraska Panhandle will see +100 degree afternoons while the inner basins see 90s. The GFS has been showing some rather hot temperatures the last few days, however runs recently are trending down thankfully. The GFS does have a warm bias at longer ranges. That being said model blends are still hot and if the ridge center slides east of our area, downsloping effects can cause temperatures lee side of ridges to heat a few degrees on top of expected temperatures.

Lets talk about the fire weather outlook. Naturally this subsiding air also dries the environment efficiently and forecasts have afternoon minimum relative humidities in the teens and single digits. Being directly underneath of such a strong ridge does have a perk, the winds are typically lessened. We will likely still see 25- 35 mph wind gust during this period, but consistent winds above 25 mph may be difficult to achieve. Regardless, the antecedent conditions and critical fuels could lead to us having afternoon critical fire conditions through much of the ridging pattern days.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 600 AM MDT Tue Jul 7 2026

Another round of showers and thunderstorms expected this afternoon as an upper level disturbance moves east across the region. Brief heavy rainfall and strong gusty winds will be the primary concerns for most terminals into this evening.

HAZARDS/WEATHER TRENDS: VFR conditions will prevail over the next 24 hours with no signal for low clouds or fog tonight. Thunderstorms will form in the mountains between 18z and 20z and push east over the high valleys and high plains between 20z today and 02z Wednesday. Kept PROB30 groups for MVFR conditions and the potential for strong wind gusts. Activity should diminish around sunset.

CYS WATCHES/WARNINGS/ADVISORIES

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