textproduct: Cheyenne

KEY MESSAGES

- High winds remains possible Thursday morning, with another round possible on Friday.

- Accumulating snow possible in the Snowy and Sierra Madre Ranges Thursday and Friday. Winter Weather Advisories are in effect.

- Above average temperatures, breezy conditions and a chance of precipitation primarily in the mountains expected through early next week, with a pattern change possible late.

SHORT TERM /THROUGH FRIDAY/

Issued at 244 PM MST Wed Dec 31 2025

A breezy day continues across the forecast area with wind gusts of 30 to 40 MPH this afternoon. Conditions remain on the mild side, with observations showing temperatures in the upper 40s to low 60s. Temperatures will remain on the mild side overnight as winds increase in the wind prones. MSLP gradients will tighten as high pressure builds over western Colorado and leeside troughing occurs east of the Laramie Range. This will increase winds aloft roughly to 50 kts over some of the wind prones areas. High winds look most favorable for the Bordeaux area based on current variables as well as in-house guidance. In- house guidance gives Bordeaux and the South Laramie Range a 40 to 50 percent chance of high winds overnight. However, decided to hold off on wind headlines tonight as the previous night's wind highlights did not verify under similar conditions.

A mild start to the year is expected on Thursday as the upper-level ridge axis sits over the Rockies. Southwest flow aloft will keep 700 mb temperatures a few degrees above 0C, which puts these temperatures above the 90th percentile for NAEFS climatology. Temperatures will once again be above average, with highs out west in the 40s, and highs east of the Laramie Range in the 50s and low 60s. These highs are roughly anywhere from 10 to 20 degrees above average for the start of January. Southwest flow will not only usher in warm temperatures, but good Pacific moisture. Southwest flow with great mid-level moisture will lead to orographic lift over the mountains, leading to snow accumulation in both the Sierra Madre and Snowy Ranges. Snow will continue Thursday night and into the day Friday. The mountains could pick of 6 to 12 inches of snow which prompted the issuance of Winter Weather Advisories. Higher amounts will be possible above 9000 feet. Hi-Res guidance does show some showers making it into the plains by Thursday afternoon, however, little to no snow accumulation will be possible in these showers as it will likely be too warm. Showers will dissipate overnight with drier conditions expected in the plains on Friday.

Ridging will flatten out more into zonal flow on Friday, leading to the potential for high winds in the usual southeast Wyoming wind prones. Winds aloft will increase up to 50 kts with strong subsidence to help bring these winds down to the surface. Temperatures will remain above average on Friday with highs in the 40s and 50s.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

Issued at 244 PM MST Wed Dec 31 2025

A quick moving system from off of California will continue to disrupt the upper level ridge pattern into the the weekend, helping to bring a bit more breeziness and mountain precipitation to the region.

Models show the leading edge of the upper level ridge to be just to the west of the CWA with a weak upper level low undercutting the area Friday night. This will bring will bring in a weak round of precipitation in the form of snow to the Sierra Madres. Raw ensembles show the heaviest snow accumulations will be Friday afternoon. Over night accumulations of up to an inch along the highest peaks will occur (80-90% confidence). Elsewhere will remain dry as the upper level ridge remains mostly in place. This will also enhance the winds along the ridgetops with models showing strong downsloping along the Sierra Madres, Snowy Range, primarily the southern Laramie Range out through the Cheyenne Ridge. Raw ensembles show wind gusts nearing 50 mph (50-60% confidence). Winds will settle overnight taking on a diurnal pattern with gusts dropping to 30-35 mph.

Saturday through Monday afternoon will remain dry as models continue to remain in firm agreement with the upper level ridge remaining in place. Dry conditions will persist through Monday. However, a disturbance will shift around the pattern bringing heightened winds back Sunday. A strong 700 mb jet will align with the North Laramie Range with a decent downsloping signal. There is also a weaker 700 mb jet aligning with the Snowy Range. 45-55% of the raw ensembles show these areas will see winds between 45-50 mph. Models show the winds settling down Sunday afternoon with winds settling to 25-30 mph gusts overnight. Models do show there is a 60-80% probability of the lower elevations seeing gusts nearing 30 mph as well.

Monday models show the back end of the upper level ridge to be breaking down as an upper level low digs in from the PacNW. South- west flow aloft will allow for some moisture advection to infiltrate the western portion of the CWA bringing in some mountain snow. In- house calculations show the ridgetops of the Sierra Madre Range has 60-80% probability of seeing 5-7 inches of snow accumulating between Monday and Tuesday. The Snow Range has 40-50% probabilities of seeing 1.5-2.5 inches. Areas between 7000-8000 feet will see between 0.5-1 inches while elsewhere will remain dry. Winds associated with this disturbance will also increase the winds Monday into Tuesday with the ridgetops seeing winds of 35-34 mph gusts (50-70%) while the lower elevations will see 25-30 mph. CB

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 1030 PM MST Wed Dec 31 2025

VFR conditions will last through tomorrow afternoon. After 18z KRWL and KLAR will start to see the celings lower with a rain/snow mix starting after 20z. KRWL may start having celings drop into the MVFR category after 00z and KlAR may drop into MVFR category by 06z at the end of this TAF period. The showers may push as far east as KCYS after 00z but not enough confidence to put into the TAF this period.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Winter Weather Advisory from 11 AM Thursday to 5 PM MST Friday for WYZ112-114. NE...None.