FXUS65 KCYS 191750 AFDCYS Area Forecast Discussion National Weather Service Cheyenne WY 1150 AM MDT Tue May 19 2026 .KEY MESSAGES... - Near record cold Monday and Monday night will lead to widespread freezing temperatures, which may damage sensitive vegetation and outdoor irrigation systems. - Slow warming trend by the mid to late week with temperatures near normal by Thursday and Friday. Numerous showers and a slight chance of thunderstorms each day, but mostly Thursday and Friday. - Above average temperatures and pleasant weather expected for the weekend. && .SHORT TERM /THROUGH THURSDAY/... Issued at 215 AM MDT Tue May 19 2026 Relatively quiet early this morning after an eventful Sunday and Monday. Additional storm total snow amounts are trickling in and there are some impressive totals across the mountains and adjacent valleys. Several reports of 12 to 18 inches from south of Rawlins over towards Rock River. The Snowy Range lived up to its name during this event with a few SNOTEL sites reporting over 3 feet of snow and nearly 3 inches of SWE! Accumulating snow has ended across the area with only a few flurries detected on radar. Main forecast concern today and tonight will be the very cold temperatures. Current observations across the area show temperatures in the middle 20s to low 30s. Portions of the area have struggling with cloud cover and/or gusty winds, but both are expected to subside over the next several hours. Kept low temperatures as is with Freeze Warnings in effect. There is also the potential for fog, but it shouldn't be widespread under CAA. Another round of freezing or near- freezing temperatures expected tonight, mainly west of the I-25 corridor. Kept the Freeze Watch in effect to see how this morning's Freeze Warnings do before upgrading. Otherwise, another chilly day Tuesday, but not as cold as yesterday with highs in the 40s to middle 50s for southeast Wyoming, but not as cold across western Nebraska with highs 55 to 60. May see a few lingering snow flurries or sprinkles today near the Colorado border and in the mountains. Slight warming trend for Wednesday and Thursday, but northwest flow aloft will continue...so temperatures during the afternoon will struggle to reach the 50s west of I-25, and 60 for areas east of I-25. Instability will still be present in this pattern, and models tend to underestimate daytime convection. Kept 20 to 40 percent POP for Wednesday with scattered rain showers and isolated thunder expected, mainly where it's warmest along and west of I-25. Some snowpack may remain over Carbon and Albany counties...even on Thursday...which will greatly decrease potential for convection. Even Thursday morning, low temperatures in the upper 20s and low 30s are expected over the high valleys of Carbon and Albany counties. Later on Thursday, models show a potent clipper system out of Alberta Canada digging south into Wyoming and slowing down. Will have to monitor this system for additional mountain snowfall, but expect most of the lower elevations to stay as rainfall. Good forcing with this clipper with another shot of cooler air. Daytime instability will aid in shower and thunderstorm development with CAPE values between 400 to 800 j/kg. Could see some decent rainfall amounts into Friday. Increased POP above 60 percent for most of the area with the likelihood of multiple rounds of showers moving through the region. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... Issued at 303 PM MDT Mon May 18 2026 A secondary vorticity maximum will propagate across our region on Friday, combined with PWAT near the 60th percentile, resulting in another chance for a few showers and thunderstorms with little change in high temperatures from the previous day given the cloud cover. Into the weekend, 500 mb heights rise as weak longwave ridging establishes itself across the Rocky Mountain West, resulting in a warming trend and mostly dry conditions. High temperatures are expected to be near climatology (average high in Cheyenne on May 23 is 67 degrees), with 60s west of the I-25 corridor and 70s further east. The warm up will continue Sunday into Monday as the ridge axis shifts over Wyoming, resulting in above-average temperatures and little to no chances of precipitation. && .AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/... Issued at 1141 AM MDT Tue May 19 2026 KRWL is currently experiencing IFR to LIFR conditions due to localized fog, but this should begin to clear out over the next hour or two. Thereafter, expecting light winds and VFR conditions all sites through the early night hours. Precipitation may begin to move into KCYS beginning around 22Z and continue into the nighttime hours through around 04Z, with light precipitation then possible for all Nebraska Panhandle sites except KBFF as it appears to be just outside of possible rain. This precipitation will bring lowered CIGs and VIS, which could produce MVFR to IFR conditions for all sites impacted. Winds will also begin to increase, becoming breezy starting around 12Z primarily for Nebraska sites. Finally, fog may be possible again for KRWL tomorrow morning, as well as KLAR and KCYS. Have introduced VCFG for KRWL, along with lowered decks and some BR for KCYS, with higher uncertainty for KLAR and have kept it out of this TAF for now. && .CYS WATCHES/WARNINGS/ADVISORIES... WY...Frost Advisory from midnight tonight to 8 AM MDT Wednesday for WYZ102-106-107-117. Freeze Warning from midnight tonight to 8 AM MDT Wednesday for WYZ101-115. Freeze Warning from 9 PM this evening to 10 AM MDT Wednesday for WYZ104-105-109>111-113-116. NE...Frost Advisory from midnight tonight to 8 AM MDT Wednesday for NEZ095. && $$ SHORT TERM...TJT LONG TERM...NB AVIATION...CG