textproduct: Cheyenne

KEY MESSAGES

- Chances for afternoon and evening thunderstorms continue until mid week. Strong gusty winds and brief heavy rainfall are the primary threats.

- A temporary drying trend begins Mid-week and possibly continues through the end of next week.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 344 AM MDT Sun Sep 6 2026

The deepening low is slowly inching its way into the Northern Rocky Mountains. Midlevel Water Vapor shows a stream of dry air covering a majority of the forecast area, however as this system slowly lift the stream of moist inflow will be pulled into our area feeding the next wave to develop our next severe weather event this afternoon and evening. With this low creeping forward the storm coverage is expected to be a bit more scattered. Areas along and east have almost equal chances of seeing rain today if that moisture stream is pulled northward. RAP model soundings are putting up massive CAPE values in the southern half of the Nebraska Panhandle. By 21-00z the estimated CAPE values are expected to be between 3500 to 4000 joules with about 1500 joules available around 04z. DCAPE values is around 1000 to 1500 joules once again. The Hi-Res models are kind of divided but presents two scenarios. The HRRR goes right through the CWA with a cluster of storms moving northward placing thunderstorms (possibly severe) right through Platte, Goshen, and Niobrara with the Western most Panhandle counties also getting in the path before spreading out to steam roll Sioux and Dawes county. The RRFS and NBM (mpas edition) also depict this scenario. The Nam-Nest, FV3, and ARW bring the storms further west and have the storms develop in Albany, Carbon, and Converse county. Despite the NAM-Nest being one of the better models during Monsoonal moisture events, the current placement of the stream of moisture on Water Vapor better supports the HRRR scenario making it the most likely scenario currently. The newly created lake that resides in Alliance from the torrential rainfall will also have more moisture at the surface that will be available to lift than what the models are anticipating. SPC currently has in a Marginal Risk today for Wind gusts up to 60 mph and hail sized up to one inch. Don't be surprised when 0615am MDT rolls around and they put a Slight Risk over the Panhandle. Today looks to be another 2.0 to 2.5 inch hail today as the UH tracks are slightly more elongated than last nights depiction.

Monday will be interesting to say the least. So the upper level low is expected to have flattened our ridge even more and be traveling between Montana or into the Canadian Providences. This low (depending on the track) may provide enough synoptic support to produce light rain that pushes the through the Forecast area from west to east. Then in the afternoon/ evening the trailing cold front is expected to produce another phase of showers/storms. The question will be does the cold front get hung up on our mountains and pinwheels around the forecast area moving north to south now. Much like a person walking from Carbon county stumbles in Albany and is now falling towards Colorado. The other question is will we become too cloudy from the first phase to really become unstable enough to produce storms instead of a more steady light rain. If we don't stay clouded up then those areas with clear skies have a better chance of seeing storms initiated by the trailing cold front. But if we stay cloudy across the Forecast area then it will be more likely that majority of the area sees more of steady rain, maybe some embedded thunderstorms as opposed to seeing severe thunderstorms with clear skies.

LONG TERM /TUESDAY THROUGH SATURDAY/

Issued at 344 AM MDT Sun Sep 6 2026

In the long term the upper level low that was responsible for our rainy weekend and start to the week starts to push in the Great lakes region by Tuesday. Tuesday looks rather dry as we enter a more zonal westerly flow aloft. This dry westerly flow is expected to last until Thursday as agreed upon by the Global models. However, they are still continuing to trend with another low pressure system moving into the Pacific Northwest to give us another possible Friday and last through the weekend. The models haven't come to an agreement on timing and intensity as it tracks through the Intermountain West. So while we could still use the moisture for our farms and reservoirs The details of this system still remain undecided.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 1130 PM MDT Sat Sep 5 2026

Storms will move out of the vicinity of KSNY shortly after 06Z. Once storms move out, a quiet overnight is expected, with light and variable winds expected at most terminals. With the increased low- level moisture from storms, fog and low stratus will be possible at KSNY and KAIA during the morning hours on Sunday. MVFR to IFR conditions will be possible, but will likely clear by the afternoon. Another round of storms is expected Sunday afternoon.

CYS WATCHES/WARNINGS/ADVISORIES

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