textproduct: Cheyenne

KEY MESSAGES

- Quiet conditions end tonight as showers and severe weather return on Saturday, with further disturbances bringing a more active pattern through early next week.

- Somewhat drier air will move into the forecast area for Tuesday and Wednesday of next week, producing a decrease in areal shower and thunderstorm coverage, along with bringing a warming trend, though latest guidance does indicate the ridge may break down a bit and allow for more precipitation incursions.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 230 PM MDT Fri Jun 19 2026

Today will be the last quiet day for our region for a while as a more active pattern develops into Saturday and continues into next week. For this afternoon and evening, we'll see low level flow continue to shift to easterly to southerly, allowing an influx of moisture to move across the area. During the nighttime hours we could see an isolated shower develop, particularly in the Nebraska Panhandle or further west across Carbon County, but overall this risk remains slight to low. What we should most definitely see however is an influx of cloudiness in response to this surge of moisture. Cloudiness and moisture will also help to keep overnight lows a bit warmer, with temperatures in the widespread 50's.

Saturday is expected to be a very active day as we see the return of severe weather. At the surface, a developing low in eastern Colorado will include an attendant frontal boundary that will stall out along our high elevation zones, causing westerly to southwesterly flow through the Laramie Range, while easterly to southerly flow will prevail east of the mountains, continuing to pump moisture across the area. This boundary alongside the orographic lift should be the focal point for thunderstorm development. Aloft, the ridge over the area will breakdown as a shortwave rides the periphery of this feature, with a low- level jet strengthening into the afternoon and evening hours. Starting the day off, the aforementioned cloud cover could help to limit destabilization early on, but most model guidance expects that this won't be enough to stop thunderstorm development for the day. And with daytime heating shooting us back up into the 70's to upper 80's for highs, we should see plenty of warmth to promote bountiful instability. Current analysis of ensembles and high resolution guidance indicates a strong risk of both hail and even tornado potential for the area. Surface based instability is pushing 1000-2000 J/kg of CAPE, but portions of the southern Panhandle are nearing 3000 J/kg at their peak. Meanwhile bulk shear values of 50-80 knots will support rotating and strong updrafts, with very large hail possible. Hail stones exceeding 2 inches cannot be ruled out, particularly with any storms that can remain discrete. Meanwhile SRH values from the HREF show around 100-200 m2/s2, but isolated pockets nearing 300 are possible. And as the afternoon goes on into the evening, the strengthening low-level jet could fuel low level shear values of at least 20-30 knots, possibly more depending upon where it takes hold, though the most likely location for stronger shear would be the southeastern portion of the Nebraska Panhandle. If any storms can remain discrete at this time, roughly the 21-00Z timeframe, the tornado risk may be much higher than just an isolated one or two, and could include stronger and much more damaging activity. Finally, PWAT values from the increased moisture flow will help to lower LCL's while also producing a low risk of heavy, flooding rainfall. Of note, the fresh burn scar of the South Fork Fire in the northern Panhandle would be vulnerable to heavier rainfall and could produce flooding risk, and will need to be monitored accordingly should heavy rainfall train across this area. By the mid to late evening, most of the strong activity should be out of our region, though some lingering showers and thunderstorms will likely persist, but severe risk should be on the downward trend.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 230 PM MDT Fri Jun 19 2026

It will be a semi-active pattern for the long term. Sunday, a shortwave will drop down into the Intermountain West to continue our chances for much needed rain for our farmers. Some lingering mid-level moisture from Saturday will look to be sufficient for afternoon showers and thunderstorms. SPC has a Slight risk for Cheyenne County in Nebraska and a Marginal Risk from Kimball to Alliance. The rest of forecast area is in a general thunder instead of a severe risk. 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 the back half of the work week to allow some low chances for rainfall as more shortwaves push into Pacific Northwest from the Alaskan Bay.

AVIATION /00Z TAFS THROUGH 00Z SUNDAY/

Issued at 528 PM MDT Fri Jun 19 2026

Low clouds and early morning showers look likely in the morning and should clear by 18z for KCYS and the Nebraska Panhandle. After 18z the models want to develop some showers over our Wyoming terminals with Thunderstorm development right around 19z for KCYS. These thunderstorms are expected to move east and enter the Panhandle right around 21-22z and continue until about 03z after the TAF period to move out of the Panhandle. Large hail and tornadoes will be possible with any discrete thunderstorms. Severe wind risk up to 75mph will be possible if the storms merge into a line of thunderstorm after 22z progged by some of the models.

CYS WATCHES/WARNINGS/ADVISORIES

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