textproduct: Cheyenne

KEY MESSAGES

- Widespread precipitation likely late Monday through Tuesday evening, with snow possible down to elevations of 6000 feet.

- Next impactful system expected to arrive late Wednesday night through the end of the work week with another round of rain and snow and cooler temperatures.

SHORT TERM /THROUGH WEDNESDAY/

Issued at 215 PM MST Sun Mar 1 2026

Current surface analysis shows a stationary front near or slightly west of the Interstate 25 corridor early this afternoon with breezy westerly winds at Laramie, Rawlins, and even Cheyenne Airport. In contrast, Locations to the east of this boundary show northerly or easterly winds. This boundary is not expected to move much over the next 12 hours, and then drift westward as another frontal boundary moves into western Wyoming early Monday morning. Yesterday, models showed shower activity developing along this boundary, but high res guidance has delayed any shower activity until later this evening due to the change in position of the front. Removed the mention of shower activity for most areas this afternoon, but kept a 20 percent chance for tonight as the stationary front drifts west and a vort max aloft moves northeast across the region. Any precip is expected to be light and short-lived.

Another mild day on Monday before the next potent Pacific storm system moves into the region Monday night. Models show this storm system moving across the Great Basin region Monday afternoon. Low to midlevel flow will become more south to southwesterly across the Front Range ahead of the potent trough, with 700mb temperatures climbing above +4c along the Interstate 80 corridor. It will be mostly cloudy for much of the day, but believe there will be enough sun to justify high temperatures in the mid 60s to near 70 for most of the eastern high plains...and generally in the upper 50s to near 60 for the high valleys of Carbon and Albany counties. Increased high temperatures a few degrees ahead of the main cold front. Expect two windows of possible shower activity, first one will be associated with the midlevel vort max which is expected to lift northeast into the early morning hours across east central Wyoming and the northern/central Nebraska panhandle. The second window of precip should be ahead of the primary cold front, which is forecast to push into western and central Wyoming Monday afternoon and evening. High res guidance showing a decent coverage of thunderstorm activity ahead of this front. Continued to mention thunder in the forecast late Monday afternoon and Monday evening for most areas north of Interstate 80 where the best forcing, moisture, and instability will be. Dewpoints may climb close to 40 degrees across these areas, which is well above climatology for early March. A quick look at NAEFS shows the 12z to 23z PWAT above the 99th percentile for this time of the year...and nearly an 18z maximum for late winter. Increased POP in these areas towards 70% or numerous coverage of showers and scattered thunder. Most of this activity will be in the form of rain, with mainly a little snow above 9500 feet.

For Monday night and Tuesday, models have remained status quo for the Tuesday system and have not trended warmer nor cooler. One key difference, models are no longer showing a resemblance of a closed low trying to form across northeast Colorado until very late in the forecast period (mainly the ECMWF), with a positively tilted progressive trough moving through the area Tuesday evening. Model QPF has stayed mostly the same with good agreement from all ensemble guidance...generally between 0.20 to 0.40 of liquid. Placed most locations around the 50th percentile of QPF (0.20 to 0.25 of an inch), but expect some locations to get close to a half of an inch due to instability. Expect all rain below 5000 feet and mostly snow above 7500 feet. It's the far western high plains along I-25 and the high valleys of Carbon and Albany counties that have the least confidence with this system since snowlevels are questionable, in addition to most of the event occurring during the daytime hours. Model soundings have not changed much from yesterday, and still show an isothermal layer developing between 1000 feet and 3000 feet AGL for locations like Laramie and Cheyenne. At this point, forcing looks potent but brief, with models not showing as much frontogenesis compared to yesterday but still show WAA, jet dynamics, and ample low level convergence. Kept POP on the high side for QPF amounts around 0.25 for most of the area. Continued a rain/snow mix between elevations of 5500 to 7000 feet. Pretty confident that even if snow falls in Douglas, Cheyenne, and Wheatland, that pavement/surface temperatures will be too high to result in much of a travel impact with any low-end snow accumulations mainly on elevated and grassy surfaces. Places like Laramie and the I-80 Summit will need to be monitored for last minute Winter Weather Advisories for 1 to 3 inches of snow Tuesday evening. The higher mountains will likely need a Winter Weather Advisory shortly for 6 to 12 inches for the Snowy Range and Sierra Madre Range. High temperatures in the low 40s to low 50s will likely occur early in the day, with temperatures falling through the afternoon hours.

Upper level trough axis will eject east of the area Tuesday night with clearing skies and ending precipitation by midnight. All models show a shortwave ridge axis moving into the Front Range by Wednesday morning, resulting in pleasant and mild day with high temperatures in the 50s to low 60s.

LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/

Issued at 1251 PM MST Sun Mar 1 2026

Thursday, A reinforced shortwave trough will push through the Intermountain West. The models have trended the storm track to be more south in the last 24 hours of model runs. This new trajectory pushes the jetstream to our south limiting the potential for high winds later this week and increases the synoptic lift over our region increasing the chances for more widespread precipitation. Our in-house algorithm reflects this thought process as it has probability for high winds at less than 10 percent for the wind prones. However, there is still almost a 40 percent chance for elevated winds. That probability is expected to go down if this track remains consistent but also a gust between 30 and 40 mph could happen almost everyday here without a system. More importantly our precipitation chances do increase as this system passes right over our region. The 00z run (12z hasn't come in yet) of the LREF paints a wide swath of 20 percent probs across the CWA for greater than 0.10 inches Thursday into Friday. This much needed precipitation will likely vary from location to location, but it does depict decent chances for widespread beneficial precipitation during our warm and dry winter. Behind this system, colder air will move into the Intermountain West Thursday night into Friday as the trough and trailing cold front push through. 700mb temperatures will drop from the +3-4C on Thursday to a -5 to potentially -10c by Friday morning to early afternoon. This will cause the Thursday daytime 50-60 temperatures for the lower elevations to drop into the 30's and 40's for Friday. However, overnight temperatures will likely be rather stable in the mid 20's these two days. This will be due to the forecasted cloudy skies acting as a thermal blanket in the night time trapping the terrestrial radiation closer to the surface creating a stable warm layer overnight. Also because of this surge of colder air, our showers will likely switch from rain to snow Thursday night through Friday morning. While snow accumulations can vary depending on how fast the rain transitions to snow generally light accumulations are expected. THe LREF does highlight the Northern Laramie range south of Douglass and the higher elevations between Rawlins and Laramie as having the greatest probability for exceeding 1 inch of snow while the lower elevations east of I-25 have about a 10 to 20 percent chance of exceeding an inch. This weekend the Intermountain West transitions back into a Westerly flow rebounding the temperatures back into the the 40's and 50's. This will slowly increase the downsloping winds and start to dry us back out. The Intermountain West essentially becomes the middle man in between two low pressure systems moving through the North American Continent. This weekend there is decent consensus that the low pressure system will be cut off from the flow in the southwestern US as another low pressure system moves through the Canadian providences. These two systems will move the jetstream over the Rocky mountains due to the compression of the 500mb gradient. If this occurs then we could possibly see the return of high winds next week (8 March-13 March).

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1040 AM MST Sun Mar 1 2026

Winds are going to be calmer throughout the TAF period compared to the last couple of days. There is some precipitation chances tonight for KRWL and KLAR but its unclear if precip will reach the ground. The next stronger wave will start around 10z for KRWL and KLAR. There is more confidence these showers will reach the ground. Under these showers there is a chance ceilings will drop to 2,000 to 3,000ft. Through the morning the showers look to move through almost every TAF site with the exception of CYS and SNY which may get VCSH instead.

CYS WATCHES/WARNINGS/ADVISORIES

WY...None. NE...None.