textproduct: Cheyenne

KEY MESSAGES

- High wind warnings in effect tonight through Saturday for the wind prones and areas immediately along the lee side of the Laramie range

- Areas of blowing snow may impact travel conditions in the wind prone areas of southeast Wyoming.

- Prolonged period of mountain snow expected through Sunday morning. Winter Storm Warnings have been issued for Sierra Madre and Snowy Ranges.

SHORT TERM /THROUGH SATURDAY NIGHT/

Issued at 322 PM MST Fri Dec 5 2025

Tough forecast in the short term as we see one round of high winds and winter conditions give way to a second round. High wind warnings from this morning were ended early as conditions had subsided, but a fresh batch of warnings have been issued for a much larger area as we are expected to see a stronger wind event across the CWA. Models highlight a very strong 700mb jet moving into Saturday morning around 12Z, with a 60-70 knot maximum from Arlington through the Cheyenne area alongside favorable downward omega values to bring these winds to the surface, and coinciding with strong cross pressure gradients through the region to also favor these expected high winds. In house guidance continues to agree, with probabilities of 40-90% across these areas, highest in our usual wind prone locations. Because of this, high wind warnings from Rawlins along I-80 to Cheyenne and up into Bordeaux have been issued from this evening through Saturday afternoon.

Meanwhile, have continued the winter products that were already issued, including the Winter Weather Advisory for the Arlington area that does coincide with the high wind warning for overnight into tomorrow as well. While snow on the ground plus fresh falling snow could promote periods of lowered visibilities, current expectation from similar past events is that we will not achieve visibilities below 1/4 of a mile for 3 hour sustained periods, precluding the need to upgrade to a full on blizzard warning in this area. Still, expect that this snow and wind could dramatically reduce conditions and cause hazardous travel across this zone. Otherwise the mountains look on track to achieve this criteria, with the heaviest snow expected overnight tonight as a surge of moisture alongside snow ratios in excess of 15:1 helps to fuel nearly a foot of new accumulation. Expect a fairly robust system to continue our early December wintry pattern, but a warmup is on the way in the long term.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 322 PM MST Fri Dec 5 2025

Variability remains in ensemble guidance in the exact placement of the upper jet streak but all guidance does meander the jet over the region with transient shortwave activity being the primary driver of its position and orientation. There will be a 500mb jet of 100- 120kts frequently over the area and 700mb flow regularly over 50kts and occasionally over 60kts. The GFS remains on the higher end of guidance with flow over 70kts at times. With that said there is above average confidence this far out in High Wind Warnings being issued during the Tuesday to Thursday period in the wind prones with a mentionable signal for high wind potential extending into adjacent zones and event the front range at times.

Associated with the shortwave activity that will drive the wind potential will be a few surges of moisture that bring high elevation snow (up to a foot above 8000ft) and a dusting to the front range from Tuesday morning through Wednesday afternoon. One thing to look forward to in the long term for those that still are not quite ready for winter will be temperatures that are much more seasonal with highs in the 40s and 50s below 7500ft. For those areas above 7500ft expect highs in the 20s and 30s through the coming week.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/

Issued at 1040 PM MST Fri Dec 5 2025

A strong jet stream and potent Pacific upper level disturbance will push southeast over the area for the rest of tonight and into Saturday. Very windy conditions are expected for the southeast Wyoming terminals with breezy conditions across western Nebraska. Periods of light to moderate snow are expected at most terminals until 18z Saturday.

HAZARDS/WEATHER TRENDS: Main concern over the next 6 to 9 hours will be coverage and intensity of snow bands moving southeast across the area through Saturday morning. High res guidance showing some pretty intense bands of snow, even though they won't last long, impacting areas near KRWL, KLAR, and KCYS. However, westerly downslope winds will be increasing each hour, which may limit impacts for area terminals. Tricky forecast for snow, but decided to add some mention of snow and MVFR conditions...and include potential timing windows for all terminals, including western Nebraska. LIFR VIS in locally heavy snow bands possible, but confidence is less than 10%.

Very windy conditions will begin shortly for KLAR...and eventually KCYS by 12z. Expect gusts of 40 to 50 knots for all southeast Wyoming terminals through 21z Saturday, and gusts of 25 to 35 knots for the western Nebraska terminals. Some LLWS expected before the onset of the strongest winds early this morning.

CYS WATCHES/WARNINGS/ADVISORIES

WY...High Wind Warning from 8 PM this evening to 5 PM MST Saturday for WYZ106-109-110-116. Winter Weather Advisory until 5 PM MST Saturday for WYZ110. Winter Storm Warning until 5 AM MST Sunday for WYZ112-114. High Wind Warning from 2 AM to 5 PM MST Saturday for WYZ115- 117. High Wind Warning from 2 AM to 2 PM MST Saturday for WYZ118. NE...None.