754 FXUS65 KCYS 052324 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 424 PM MST Fri Dec 5 2025 .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 /00Z TAFS THROUGH 00Z SATURDAY/... Issued at 434 PM MST Fri Dec 5 2025 Light snow will slowly bring ceilings back down in RWL over the next 6 hours today with MVFR from about midnight to sunrise. Winds frequently gusting over 30-40kts in RWL, LAR, and CYS by 06z onwards and 20-30kts for Nebraska sites after 06z. Wind shear will be prevalent for all sites (minus possibly AIA and CDR) beyond midnight, predominately Westerly or NW in direction and 35-50kts in magnitude. Other than RWL and LAR all sites staying above MVFR thresholds for visibility and ceiling but still seeing ceilings drop to 4-8kft for most at some point in the period. && .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. && $$ SHORT TERM...CG LONG TERM...WFOCYS AVIATION...WFOCYS