650 FXUS65 KCYS 300522 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1022 PM MST Mon Dec 29 2025 .KEY MESSAGES... - High winds are expected for the typical gap wind areas tonight into Tuesday morning. Another round is possible Tuesday night into Wednesday morning. - Above average temperatures and breezy conditions expected through the weekend, with a chance of precipitation primarily in the mountains to end the week. && .SHORT TERM /THROUGH TUESDAY NIGHT/... Issued at 330 PM MST Mon Dec 29 2025 Clear skies are present over nearly the entire area this afternoon with temperatures generally quite closer to seasonal averages. Yesterday's upper level low is rapidly moving off to the east, with a broad ridge over the West Coast now beginning to encroach to the east again, which will support the expected warming trend over the next several days. 700-mb temperatures will return back to around 0C for Tuesday, which will help boost high temperatures about 8 to 10F warmer than where they are today. Gap winds remain the primary weather concern of the near term forecast period. With the broad ridge overhead and jet streak dynamics supporting large scale subsidence over the area, we will see somewhat of a diurnal cycle of winds developing over the next few days. During the overnight hours, surface high pressure will build in over the snow-covered interior Rockies while a weak surface trough passes over the High Plains. This will result in an increased MSLP gradient across out typical gap areas, peaking likely around 5AM tonight. Gradients and winds at 700-mb are unimpressive, but 850- mb and surface pressure gradients are marginally supportive of high winds in the typical gap areas. As a result, decided to upgrade the existing High Wind Watches to Warnings, and expand this to the Bordeaux area as well. As mentioned by the prior forecast, confidence is a little lower for the Bordeaux area due to more inconsistent signals for subsidence reaching far enough east towards I-25. Expect winds to drop off by early Tuesday afternoon, with breezy conditions spreading over much of the area after. This overall pattern is expected to repeat Tuesday night into Wednesday morning. Another weak surface trough traversing the plains will boost the MSLP gradient again Tuesday night. Most measures of the cross-barrier gradient appear a little weaker tomorrow night compared to tonight, with the exception of the Arlington to Bordeaux MSLP gradient which is better correlated with Bordeaux's winds specifically. In-house guidance gives approximately a 40% probability of high winds for each of the three primary gap wind areas for the Tuesday night/Wednesday morning period. Tonight's event will be a good trial run with this setup, which will likely inform any potential warning decisions for the next event. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... Issued at 239 PM MST Mon Dec 29 2025 A relatively calm long term forecast period is expected, as high pressure ridging brings above normal temperatures and dry conditions on Wednesday, but a quick moving system from off of California will disrupt this pattern beginning Thursday and continuing into the the weekend, helping to bring a bit more breeziness and mountain precipitation to the region. Wednesday will be a benign day as high pressure ridging controls the region and we see above normal temperatures and dry conditions, but clouds will be building as moisture begins increasing across the area. On Thursday an upper level low will move inland across California and then across our region through Friday, disrupting the ridge and bringing mountain precipitation alongside breezy winds. In house guidance indicates the potential for high winds to return to our wind prone locations, with Arlington seeing peaks of around 50-65% probability for gusts 58+ Thursday through the weekend. Meanwhile we'll see a moisture plume move across the region, but with a lack of significant forcing the bulk of this activity should be driven by orographic enhancement via southwesterly flow, leading to mostly mountain precipitation in the form of high elevation snow. And overall QPF amounts aren't overtly impressive, so while some fresh snow will be welcome for the area, overall accumulations shouldn't be on the high side. After this system moves across, ridging should re-establish into Saturday, but another quick moving system should help to flatten this feature out while bringing another chance of breezy winds as the jet begins to settle over the area. Meanwhile our temperatures should stay relatively similar through the period without a stronger cold airmass to interrupt, leading to continued above normal highs with temperatures east of the Laramie Range in the 50's to 60's, and to the west in the 40's. The new year will be starting off similarly to how our Christmas went, with warmth and wind. && .AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/... Issued at 1021 PM MST Mon Dec 29 2025 The remainder of the overnight will feature calm, VFR conditions. Clear skies and light winds are expected to continue through mid- morning. LLWS will be possible at KLAR and KCYS due to strong winds aloft. Winds at the surface will begin to increase late morning, with most terminals seeing diurnal gusts of 20 to 25 kts. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...High Wind Warning until 11 AM MST Tuesday for WYZ106. High Wind Warning until 1 PM MST Tuesday for WYZ110-116. NE...None. && $$ SHORT TERM...MN LONG TERM...CG AVIATION...SF