textproduct: Cheyenne

KEY MESSAGES

- Mild temperatures return to the region for this weekend as upper-level ridging moves in.

- Mountain snow and high winds possible in the wind prones and wind prone adjacent areas of southeast Wyoming on Sunday.

SHORT TERM /THROUGH SUNDAY NIGHT/

Issued at 235 AM MST Sat Jan 3 2026

Another day ahead that will not seem like early January with no snow in sight for many locations across southeast Wyoming along with temperatures more reminiscent of fall/spring, not the heart of winter. Upper level ridging builds across the CWA today, so expect a pleasant day under mainly sunny skies and warm temperatures. Put that thick winter coat away and get out those shorts with temperatures soaring into the 40s west of I-25 and 50s to low 60s east of the corridor, warmest across the Nebraska Panhandle. Don't expect much cooling Saturday night as lows will only dip into the 30s. More of the same, with regards to temperatures, across the CWA for Sunday.

The benign conditions will come to an end Saturday night with a change in the mid/upper levels. The ridging mentioned earlier will slide off to the east while a shortwave moves up the backside into our western forecast zones, with southwest flow, this portion of our CWA will see an increase of mid-level moisture. As said moisture reaches the mountainous terrain, this change in the topography will help in lift, thus increasing chances of snow across the higher terrain of the Sierra Madres Saturday night. Now for the main event in the short term, a return of strong winds after a brief lull by Saturday night. You read correctly, strong winds will make a return late Saturday night into Sunday. A 700mb jet maximum will slide into our CWA with winds 65-70 knots, this coupled with ample subsidence, negative Omega (GFS), will help mix these winds down to the surface. Not only this, but a tight surface pressure gradient will develop along with a lee side, all working together to ramp up the winds. So, expect winds to increase into the 30-50 mph range with gusts topping out near 70 mph, strongest affecting are usual wind prone areas across southeast Wyoming. There is the possibility that some of these stronger winds may make into the Cheyenne area. In-house guidances continues to show high probabilities for a high wind event starting late Saturday night into Sunday morning. As such, high wind products may be needed later this morning, holding off for now, waiting to see additional runs of in-house guidance. As quickly as these winds begin, they will end just as fast as the 700mb jet maximum will shift off to the east Sunday afternoon along with a weakening surface gradient, so the strong winds will wind down by Sunday evening.

LONG TERM /MONDAY THROUGH FRIDAY/

Issued at 235 AM MST Fri Jan 2 2026

No major changes to the long term forecast. Please see previous discussion...

Models are in firm agreement with an upper level low off the coast of California pulling the gradients aloft to a southwest flow Sunday night through Monday before flattening and becoming westerly flow aloft Wednesday. This will bring in some moisture advection from the southwest and west with snow returning to the mountains. Snow will persist across the Sierra Madres and Snowy Range through Tuesday with higher accumulations in the Sierra Madres. Raw ensembles show 70-80% probabilities of 7-8 inches of snow in the Sierra Madres and near 3 inches of snow in the Snowy Range beginning Monday afternoon and persisting through Tuesday afternoon. Models show surface CAPE values of up to 500 J/kg so, not only will there be snow, but deterministic guidance also shows 15% probabilities of thunderstorms across the Sierra Madres between 11 AM Monday through 5 AM Tuesday. Snow will continue through Tuesday afternoon at 11 PM with another round of accumulations of 3-4 inches along the Sierra Madres with 55- 65% probabilities.

Models show a break in precipitation as the upper level flow turns westerly before becoming southwest again Wednesday and bringing in more moisture from the southwest through Friday night. In-house guidance shows snow accumulations from 11 AM Wednesday through 5 PM Friday to be near 11 inches along the ridge line of the Sierra Madres and near 6 inches along the Snowy Range. Guidance also shows the lower elevations could see a skiff of snow as well with 45% probabilities even this far out.

Winds will remain slightly elevated Monday through Wednesday as the 700 mb jet makes slowly makes its way to the east and winds turn more to a southwest flow aloft. 500 mb winds will drop from 70 kts to around 40 kts which will continue to allow mixing at the surface. However, not nearly as strong at the last few events. In-house guidance show winds to be elevated as apposed to high. Raw ensembles shows winds will be primarily diurnally driven with peak gusts between 30-35 mph with some locally higher gusts in some isolated locations (70-80% confidence) As for the areas east of Laramie Range, winds will also be diurnally driven with peak gusts between 25-30 mph and 60-80% confidence. After Wednesday, models begin to diverge and show at least some sort of southwest flow aloft. Raw ensembles and in-house calculations all show the winds to remain diurnally driven and below 25 mph at the surface Thursday and Friday.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 420 AM MST Sat Jan 3 2026

VFR conditions will prevail across all terminals for the entirety of this TAF period. Winds will generally be less than 10 knots for most of this forecast; however, gusty winds up to 40 knots will start to impact KRWL and KLAR around 07Z Sunday. By the tail end of this TAF period, gusty winds to 30 knots will make it to KCYS.

CYS WATCHES/WARNINGS/ADVISORIES

WY...High Wind Watch from late tonight through Sunday afternoon for WYZ101-107-108-117-118. High Wind Watch from this evening through Sunday afternoon for WYZ106-110-116. NE...None.