textproduct: Cheyenne

KEY MESSAGES

- Widespread rain and mountain snowfall expected today and Monday as a central Pacific system lifts northeast across the region. - Near normal temperatures and a bit warmer by Tuesday through Thursday, but the next Pacific system will be approaching from the eastern Pacific later in the week.

SHORT TERM /THROUGH MONDAY NIGHT/

Issued at 212 PM MDT Sun Oct 25 2026

What a difference a day will make as we see a more active weather pattern through Monday morning across the CWA as a stout upper level low moves from the Desert Southwest into the region. But first, lets take a quick look at today's temperatures with highs west of I-25 topping out in the lower 50s and lower to upper 40s east of the corridor. While lows tonight dip into the lower to mid 30s. Switching gears a bit and taking a look at the upper levels, initially we have a cut off low over the Desert Southwest while we sit under a southwesterly flow regime with a ridge to our east across the Mississippi Valley. As we progress through this afternoon, the cut off low will lift northeast and as it does so, the flow aloft over the CWA will become difluent, this combined with a plume of Pacific moisture and favorable ascent will support increased precipitation chances across the CWA by the late afternoon hours through the overnight into Monday morning.

Lets take a closer look at today through Monday morning, the low over the Southwest will continue to lift northeast closer to our CWA. Guidance indicates a surge of moisture ahead of this system, with ensemble members having PWATs above and around the 98th percentile. With adequate forcing, moderate rainfall looks to be a possibility. So, with ingredients in place, this looks like a scenario where up to 0.5" of rainfall, locally higher amounts, are possible across southeast Wyoming. With the best dynamics setting up over the Nebraska Panhandle, many locations there have the best chances of seeing 1.0" of precipitation. With this system moving in, especially in the afternoon hours, it is not out of the realm of possibility to see a few embedded weak thunderstorms as there is some instability in place, albeit a very slight chance. The coverage with regards to the rain showers will initially be scattered in nature then become more widespread this afternoon into the evening/overnight hours, when the heaviest of the precipitation is expected due to the influx of Pacific moisture. As we head into the overnight hours, the upper level low will slide northeast across the CWA. As it continues to lift off to the northeast Monday morning, rain showers will linger across the Nebraska Panhandle with clearing off to the west. This clearing will continue through the day as the system lifts out of the region, from a west to east. Most of the precipitation should remain as all rain, but for the late evening hours through the overnight can't rule out a few snow flakes mixing in. Not expecting any accumulations at lower elevations due to the warm soil temperatures, but higher elevation may see sub-advisory snowfall, with amounts on the order of 5.0" or less.

Expect slightly cooler temperatures Monday to hang on east of the I- 25 corridor as highs will only top out in the lower to mid 40s across the Nebraska Panhandle while elsewhere highs will approach the low 50s. Looking west of I-25, highs will top out into the lower to mid 50s. Lows Monday night will tank into the lower 30s, to near freezing.

LONG TERM /TUESDAY THROUGH SUNDAY/

Issued at 150 AM MDT Sun Oct 25 2026

No major changes in the long term period, please see previous discussion...

Medium to long range models in reasonable agreement through late week, with a period of quiet weather expected for southeast Wyoming and western Nebraska during the middle of the week. Models show moderate southwesterly flow across the area with the polar jet staying north of the Front Range, and the subtropical jet staying well to the south over Texas and northern Mexico. We're kind of in- between these two separate storm tracks for most of the week with mostly quiet weather expected and near or slightly above average temperatures. A pair of potent Pacific shortwave troughs are forecast to impact the area late this weekend and early next week, with the second one likely missing southern Wyoming and remaining north of the area Tuesday. Models show a surface "cold front" rapidly moving east and clipping the forecast area to the north. However, all this front will do is shift low to midlevel winds into the west and increase wind speeds on Tuesday and Tuesday night...producing somewhat warmer downslope winds for a bulk of the area, including the high plains. Will need to watch for High Wind criteria for the typical wind prone areas of southeast Wyoming since most models show 700mb winds increasing over 45 knots by Tuesday morning and remaining elevated through Tuesday night with a decent surface pressure gradient and some hint of brief mountain wave activity. At this time, in-house wind guidance shows probability of wind gusts over 55 MPH around 20% to 45% for Arlington, Bordeaux, and even some of the sub wind prone areas along Interstate 25 near Douglas. For now, increase wind speeds up to criteria but did not increase wind gusts over 60 MPH quite yet. Event should be pretty brief and not too widespread, and peak mid Tuesday morning. Models have backed off on winds Tuesday night/early Wednesday with a slight downward trend, so kept those winds lower for now.

Downslope winds should result in relatively mild temperatures for this time of the year Tuesday through Thursday, but not quite as warm as it has been prior to this weekend. Kept high temperatures in the upper 50s to upper 60s, warmest of the eastern plains below 5000 feet and coolest temperatures across Carbon and Albany counties. Peak temperatures should occur later in the week with highs approaching 70 degrees over the western Nebraska panhandle as an upper level ridge axis across the southern United States and the Gulf amplifies ahead of the next Pacific storm system. Model solutions begin to diverge at this time, which is to be expected nearly 7 days out, as potential long wave trough attempts to settle across the eastern Pacific Ocean with a potent storm system pushing inland and into the Great Basin Region by late next Saturday and into next Sunday. Will have to keep an eye on this storm later in the forecast period as some model solutions and ensembles show a decent amount of colder air along with a subtropical moisture tap from the central Pacific. This pattern typically favors lee-side low pressure systems and an active weather pattern for the Front Range.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 539 PM MDT Sun Oct 25 2026

A complex weather forecast for terminals, particularly for Nebraska Panhandle terminals. An upper level low pressure is located to our west with two distinct vorticity maximums. The southern max is anticipated to strengthen through the night into tomorrow. Increasing rain chances and cloud coverage will occur as this vort max incites surface cyclogenesis on the lee side of the Rockies and treks northeast into the Panhandle. Recent observations from terminals indicate MVFR to IFR conditions are already occurring. Continued lowering of CIGs and visibility are highly confident along and east of I-25 through the morning. Periods of LIFR seem likely, but the timing is tricky. High resolution models indicate that airfield minimums will be, at times, met off and on. Adverse conditions continue until about 16 to 20Z Monday. A crossover to snow is possible at KLAR and KCDR. After about 16Z, at KRWL and KLAR, winds increase to 12-16 knots out of the southwest with gusts to above 25 knots possible. Clearing from west to east is anticipated through the afternoon and evening hours. All terminals are anticipated to stay above freezing through this forecast period.

CYS WATCHES/WARNINGS/ADVISORIES

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