textproduct: Cheyenne

KEY MESSAGES

- Scattered strong to severe thunderstorms are anticipated this afternoon and evening across much of the area.

- All severe weather hazards are possible today, but the greatest concern is the risk for large hail.

- Daily chances for showers and thunderstorms will continue through much of the week ahead with temperatures near average west of I-25, and cooler than average east of I-25.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 150 PM MDT Sat Jun 20 2026

Active weather is on track to return to the area this afternoon. GOES satellite imagery shows a potent upper level low over the northern Rockies approaching the area today. A dry slot to it's south is pushing into south central Wyoming at this time, while plentiful moisture is entrenched over the High Plains. With a surface high sitting over the northern Plains, south to southeast flow dominates today, supporting the influx of low-level moisture. Cloud cover has broken up west of a line from roughly Pine Bluffs to Chadron, but low clouds remain fairly entrenched over the rest of the Nebraska panhandle. Expect the cloud cover to continue to erode this afternoon, but it may not totally clear out at all today. As a result, the forecast temperature for portions of the Nebraska panhandle was decreased considerably through the afternoon.

Looking towards the convective threat this afternoon, we will see the dryline become better defined along the Laramie Range as drier air mixes down to the surface in southern Carbon and Albany counties. Ahead of the approaching shortwave trough, expect vertical wind shear to increase as the day progresses, with strong synoptic forcing for lift kicking up this afternoon as well. Potent instability is already developing in southeast Wyoming, and this is expected to grow in western Nebraska shortly. However, due to the morning cloud cover, the capping inversion is still quite strong, especially in Nebraska. West of the state line, CIN is expected to break down by mid afternoon, but this may not occur at all to the east. Normally this would prohibit thunderstorm development, but today, the large scale ascent is substantial enough that we may be able to sustain elevated convection overtop the low-level inversion. MUCAPE is already pushing around 1000 to 2000 J/kg and progged to climb towards 2000 to 3000 J/kg later this afternoon. So, we are generally expecting surface based convection to develop around 1-2PM along the Laramie Range (tied to the dryline), and then grow upscale as they move eastward. Upon reaching the state line, storms will either weaken as they lose surface instability, or they will be able to tap into some elevated instability and maintain or strengthen. It's difficult to say which storms will take which path at this time, but expect to see a little of both occurring today. The primary hazard will be large hail today, but all severe weather hazards are possible. For Carbon, Albany, and Converse counties, strong to damaging winds will be the primary concern, but isolated hail will still be possible in these areas. Late this afternoon and through the evening, east to southeast winds will increase, leading to fairly potent low level shear over the High Plains. Even if storms become elevated, this may allow for a few tornado spin- ups, with the primary risk area remaining in far southeast Wyoming and the southern Nebraska panhandle. Due to the strong forcing, multiple rounds of thunderstorms will be possible. While the primary window for severe weather is between 2PM and 10PM, a few storms may linger as late as 1AM. Due to these expectations, a Tornado Watch has been issued for the southern Nebraska panhandle, and a Severe Thunderstorm Watch has been issued for remaining portions of the area.

Sunday will start off with a few areas of isolated fog across the High Plains following the moisture return, but winds will turn westerly shortly after sunrise following the passage of a surface trough / weak cool front. Localized strong winds are possible (30% chance) along the typical wind prone areas of I-80, with breezy conditions anticipated elsewhere. Look for another round of scattered afternoon showers and thunderstorms. A few storms will have the potential to become strong to severe, but the risk will be a bit lower thanks to vertically stacked winds.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 150 PM MDT Sat Jun 20 2026

Monday into Tuesday, A low pressure system drops into a the Northern Plains sending a frontal passage through our area. This weak front will bring some cool air over the Intermountain West keeping our temperatures mostly in the 70's for both days but some isolated 80 temperatures will be possible as warm dry air starts to also push in from the West. As more of the dry air begins to filter in over night RH values West of I-25 will start to drop into the teens while everything east will stay into the 30's and 40's. This dry air will most likely follow the upper level ridge that sets up on the West coast and slightly pushes east. The ridge does look to compress on Thursday and Friday to allow for some continued chances for rainfall as more troughs/system push into Pacific Northwest from the Alaskan Bay. This active pattern could potential last through the weekend if the ridge and dry airmass stay centered over the southwestern part of the United States.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1152 AM MDT Sat Jun 20 2026

Low stratus is slowly lifting out of IFR and into MVFR range. The plus side to this low stratus deck is that it may inhibit severe convection this evening but we shall see. Today's severe thunderstorm potential really lies over KCYS and the Nebraska terminals. KLAR and KRWL may see some vicinity showers and rumbles of thunder but that may be it as the models and dynamics put the storm potential in the lower elevations today.

CYS WATCHES/WARNINGS/ADVISORIES

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