textproduct: Cheyenne

KEY MESSAGES

- Dry conditions and above average temperatures will continue through Friday.

- Elevated to critical fire weather conditions likely Friday afternoon into the early evening, with the potential for gusty showers.

- A pattern change Sunday into Monday will drop temperatures closer to near seasonal normals, and bring renewed chances for rainfall primarily in Carbon and Converse counties.

SHORT TERM /THROUGH FRIDAY NIGHT/

Issued at 247 PM MDT Thu Oct 8 2026

The anomalously warm pattern continues over the next 48 hours across SE Wyoming and the Nebraska Panhandle beneath an upper-level ridge that has been responsible for the unseasonably hot temperatures so far this month. This longwave ridge will begin to flatten into tomorrow ahead of a shortwave trough digging into the Pacific Northwest, which will set the stage for more unsettled weather into early next week.

Current radar imagery shows a few weak convective showers across Larimer and Jackson Counties south of the state line that are likely being driven by differential heating of the higher terrain. These are also being aided by another weak influx of subtropical moisture being advected in from the southwest along the western periphery of the mid and upper-level ridge, resulting in PWAT around 0.4" (which is surprisingly around the 80th percentile relative to climatology). Due to very weak (5-10 knot) 850-300 mb flow beneath the ridge, not expecting any of the showers to make it off onto the plains. Kept some very low (<15%) PoPs over the extreme Southern Laramie Range if a gusty shower happens to sneak in from Colorado from the south and west, but confidence and likelihood of this occurring is far too low to mention in any deterministic wording. Even if this happens, surface dewpoints are in the low to mid-20s with temperatures in the 70 with even some lower 80s, so any light precipitation would evaporate before reaching the surface. As for fire concerns, despite afternoon critical RH values of 10-15% along the I-25 corridor, the limiting factor for Red Flag conditions today will be the lack of winds. Gusts are peaking between 15-20 mph in the region of lowest RH, so no fire highlights are in place for this afternoon. Temperatures have again continued to be 15 to 20 degrees above average, with Laramie having a decent shot at tying their daily record on 75F set way back in 2020. Tonight will be similar to the previous couple of nights, with mainly clear skies and light winds of 5-10 knots. Despite conditions that are conducive for effective radiative cooling, overnight lows will still remain around 10 degrees above average underneath the ridge.

Friday will be slightly more interesting than today (although not in a good way), as our winds will increase drastically from today thanks to low-level response from lee cyclogenesis occurring up north across Alberta and Saskatchewan. This will bring an increase in SW winds tomorrow morning into the afternoon hours, with gusts as high as 35-40 mph primarily north of I-80 thanks to the increasing gradient flow. Combined with critical afternoon RH values ranging from 11-18%, a Red Flag Warning has been issued for tomorrow afternoon/evening until 7PM MDT, mainly for SE Wyoming locations north of the I-80 corridor, and for the extreme northern Nebraska Panhandle. Temperatures tomorrow will continue to remain above average given the gusty, downsloping flow regime. Locations across the Panhandle have the greatest chance at reaching or breaking record highs for this day as the 500 mb ridge axis shifts towards the east. It is likely that many locations in W Nebraska reach the upper 80s to perhaps 90 degrees for afternoon highs.

With the onset of mid and upper-level subtropical moisture embedded in the SW flow pattern ahead of our next series of systems, tomorrow will also increase our chances for high-based, gusty showers tomorrow afternoon into the evening, with perhaps a lightning strike or two given MLCAPE around 100 J/Kg. Although instability is quite weak (though still impressive for October) and while the low-levels are very dry, any of these showers will be capable of producing gusty, erratic winds at the surface, in addition to dry lightning. These hazards will not only escalate the anticipated fire concerns, but also outdoor activities on Friday afternoon and evening for those looking to get one last taste of summer before the cooler weather next week. Have decided to increase PoPs as CAMs have started to pick up some increased coverage of showers/storms beginning sometime early to mid-afternoon into the evening. The highest confidence in gusty shower coverage tomorrow afternoon and evening will be over the higher terrain of SE Wyoming, therefore have included the highest PoPs here (~15-20%), with much lower confidence (5-10%) in the Nebraska Panhandle.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

Issued at 247 PM MDT Thu Oct 8 2026

In the long term we're finally going to see active weather as troughing begins to take over the western US with an uptick in moisture and instability fueled by the remnants of two tropical systems lifting up from the Pacific. Over the weekend we'll see ridging breaking down and moving off to the east as two lows overtake the West Coast, one from the north and one from the south. These two systems will continue to merge bringing a large and deep cutoff upper level low that will control the Western US into the start of the work week. As flow turns more southwesterly during the weekend, we'll see a notable influx of moisture overspread the region. This should begin to fuel shower chances that will just barely move into the CWA on Saturday ahead of a cold front which will slowly drop down across the region through Sunday. Current forecast calls for precipitation to struggle to move further than the high terrain through Sunday as the bulk of the moisture remains confined further west, bringing stronger impacts across western and northern Wyoming. Also of note, this initial push of colder air won't be nearly enough to completely shut down our October masquerading as summer, with highs on Saturday still 12-18 degrees above normal as 700mb temperatures still remain around 10-12C on Saturday, and then slightly cooling on Sunday with highs still 8-12 degrees above normal in the 60's to 70's.

Monday into the middle of the week the closed upper level low off of California will begin to weaken by Tuesday and then eject across the Rockies Tuesday into Wednesday, becoming absorbed by upper level flow as another trough begins to then develop to bring further impacts just beyond the long term. While ridging will be able to amplify to our east across the Mississippi River Valley, we'll remain in a split flow between this and the troughing to our west. The NBM brings at least a low-end chance of some precipitation on Monday and Tuesday as moisture remains with PWAT values slightly above normal, but this also means our temperatures should hover where they stood on Sunday in the 60's to 70's. Wednesday is when we should finally see cooler conditions and a bit more widespread precipitation occur as the aforementioned West Coast low ejects across the Rockies and just south of our region. While highs will be a few degrees cooler and near normal to the west of the I-25 corridor, temperatures further east should still remain a few degrees above normal in front of the cold front. But the long term doesn't end without a shot of colder air, as the overnight lows moving into Thursday morning should drop into the 30's to 40's, with some locations getting their first freeze of the season potentially. And with air this cool, the mountains should finally dip low enough that snow will begin returning to the higher terrain of the region. This could even spread down into the adjacent valleys and lower terrain, but don't expect our first significant snow storm just yet as this will likely be mixed with rain and brief for the most part. But snowy peaks may finally be on tap as we beginning moving into the second half of the month, and relief from our warm and dry conditions is expected.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 1200 PM MDT Thu Oct 8 2026

VFR conditions expected over the next 24 hours. A few high clouds to clear skies expected, though some scattered lowered ceilings may be possible this evening near KCYS. These lowered CIGs will be from precipitation just south of the region in Colorado, but at this time keeping any mention of it out of the TAFs due to low probs. Winds breezy this afternoon, should lessen during the evening before picking back up late tomorrow morning into the afternoon, with gusts of 20-30 knots possible generally from a westerly to northerly direction.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Red Flag Warning from noon to 7 PM MDT Friday for WYZ417>422- 425-427-432. NE...Red Flag Warning from noon to 7 PM MDT Friday for NEZ434.