textproduct: Cheyenne

KEY MESSAGES

- Red Flag Warning in effect for Converse and Niobrara Counties.

- Warming and drying trend expected through the end of the week.

- Precipitation chances return for the beginning of next week.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 532 AM MDT Fri Sep 4 2026

A weak surface low is pushing through the area this morning sparking some weak thunderstorms for the Nebraska Panhandle. The RAP extends a finger of 300 joules of CAPE across the northern periphery of this low helping to sustain these weak thunderstorms. They haven't been producing a lot of rain as the Scottsbluff ASOS reported only a trace of rain and Alliance only reported lightning as these showers passed over them. This afternoon and evening an isolated shower will be possible. Another weak shortwave will be pushing through around peak heating at 21/22Z. Besides the shortwave providing some synoptic support, the convective temperature around 90 will likely be reached in areas east of the I-25 corridor. Also accompanying this shortwave is a stream of vorticity that will be kind of moving ENE from Laramie county and into the Panhandle. Despite the synoptic support given to the storms the models aren't too excited about today. The reason may be is that there is very little moisture at the surface. Model soundings show a pretty stout inverted V sounding but the models also show the afternoon RH values to hover between 15 to 20 percent. So with little moisture and only decent synoptic support today may agree with the models showing an isolated to slightly scattered thunderstorm day. SPC would also agree with the models in this particular lack luster of a day as our portion of the Intermountain West is only covered by a general thunder where lightning will be the main threat. Also considering how dry the surface will be there will be also a slight risk for dry thunder. The HRRR and Nam Nest have lingering showers lasting through to Saturday morning. However, showers until 11Pm may be more reasonable as the RAP shows the wave moving out of the area by 11pm with almost no energy left for the storms to utilize. Saturday, will be kind of the same story. The low pressure system just off the West coast will send another shortwave through our region. The moisture content will be marginally better than today as the low pressure system helps funnel moisture from the Pacific ocean and into the Rocky mountains. The Hi-res models are more excited about the storm situation on Saturday than today. THe RAP places about 1500 joules along the eastern portion of Laramie county and the majority of the panhandle. There is some vorticity support with Saturday but the deciding factor for Saturday will be how much moisture is the Low able to send into our area. The best timing for shower/storm development looks to be after 3pm for our area with the models quickly pushing the storms out of our area around 7pm. However, the major vorticity support does come later into the evening. So the most likely scenario looks to be some scattered showers with a couple of potential supercells. SPC has drafted a Marginal risk for severe thunderstorms in the Nebraska Panhandle were the environment is ever so slightly better for sustaining thunderstorms.

LONG TERM /SUNDAY THROUGH THURSDAY/

Issued at 532 AM MDT Fri Sep 4 2026

Sunday, the low over the Pacific Northwest starts to push against our upper level ridge as it tries to push further into the interior of western United States. When this occurs more of the monsoonal moisture will feed over our region priming the Intermountain west for more storm activity. The storm coverage will slowly increase as well as more moisture feeds into the region. The system will inch towards the Intermountain West and start to flatten our ridge.

The trend of showers and thunderstorms continue through Monday and Tuesday as the stubborn trough to the northwest finally ejects into the central plains. While moisture will remain high, a lobe of drier air associated with a ridge to the east may be pulled in ahead of the trough which would reduce rain potential. However, since the trough is ejecting it is possible that cyclogenesis occurs nearby increasing the severe weather potential. Some machine learning models are highlighting an uptick in that potential for the Nebraska Panhandle area. The details of how this unfolds will be ironed out as we get closer.

The remainder of the long term is in a drying trend. The ridge noses in. This would not completely shut down storm activity.

AVIATION /12Z TAFS THROUGH 12Z SATURDAY/

Issued at 515 AM MDT Fri Sep 4 2026

High based showers and thunderstorms will be moving through the Northern Panhandle this morning producing very little rain as they move through. Another shortwave is expected today with isolated chances of hitting an airport today. There isn't very much moisture at the surface so the most likely threat will be lightning and gusty outflows that may provide a little wind shear if it hits a terminal. Confidence isn't very high in these shower locations or impacts to the terminals. VCSH was put into the TAF for the best timing of any possible showers hitting the terminal. For areas east of I-25 including KCYS the best window looks to be from 21z to 03z. For KLAR and KRWL showers aren't anticipated to affect the area as this looks like more of a lower elevation storm day and not the typical storms start in the mountains and move down into the lower areas.

CYS WATCHES/WARNINGS/ADVISORIES

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