textproduct: Cheyenne

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 /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1122 PM MDT Mon May 18 2026

Rain/snow activity will be coming to an end across all the terminals over the next hour or so. With the added moisture we've seen across southeast Wyoming coupled with winds becoming light and variable, BR and/or FG may develop and impact KRWL, KLAR, and KCYS with VIS 1SM or less and CIGs down to 500 feet, possibly lower at times. After about 15z, CIGs and VIS will improve for the aforementioned terminals. For the Nebraska Panhandle sites, CIGs will lift overnight with winds generally staying variable to around 6 knots.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Freeze Warning until 10 AM MDT this morning for WYZ101-102- 106>108-113-115>119. Freeze Watch from late tonight through Wednesday morning for WYZ101-115. Freeze Warning until noon MDT today for WYZ104-105-109>111. Freeze Watch from this evening through Wednesday morning for WYZ104-105-109>111-113-116.

NE...Freeze Warning until 10 AM MDT this morning for NEZ002-003- 019>021-054-055-095-096.