textproduct: Cheyenne

KEY MESSAGES

- Winter Weather Advisories have been issued for the Sierra Madre, Snowy, and North Laramie Ranges, as well as the I-80 Summit and Arlington area today and tonight through 5 PM Tuesday.

- Isolated to scattered showers and thunderstorms possible today with above average temperature and moisture present, and instability driving some stronger thunderstorm activity moving into Carbon County.

- Another round of accumulating snow is expected Thursday morning through Saturday morning. Exact accumulations uncertain at this time.

- Upper-level blocking pattern may start this weekend, leading to the potential for multiple rounds of precipitation across the region.

SHORT TERM /THROUGH WEDNESDAY NIGHT/

Issued at 221 PM MST Mon Mar 2 2026

Our next impactful system is moving into the region this afternoon bringing thunder to Carbon County and winter weather to our high elevation and mountain zones. As the trough moves eastward through the region, synoptic forcing is favoring thunderstorm development in our western zones, and solid instability is keeping this threat a reality. Current mesoanalysis shows around 500 J/kg of MUCAPE in the region where thunderstorm initiation is ongoing, and a storm just outside the CWA is registering the potential for small hail, with webcams as of this writing confirming that on the roadways. With favorable conditions present, particularly in Carbon County, don't be surprised if we continue to see some relatively strong storms for this time of year before weakening into the evening hours. Otherwise the other feature from this system in the form of winter weather is impacting our high terrain zones and mountains. Latest high resolution guidance is indicating a bit more precipitation making it into the Arlington area thanks to upslope flow from northerly to northeasterly winds. Based on this guidance, went ahead and added this zone to the winter weather advisory for around 2 to 5 inches of accumulations, but don't be surprised to see some isolated locations nearing the mountains to see heavier totals. Along the I-80 corridor, we should see around 4-5 inches, so notable impacts to travel in this area could occur. Not confident enough that we'll see 6 inches or just over at this time, so held off on a Winter Storm Warning for now, but the bulk of the heaviest accumulations begin later tonight into the morning hours tomorrow, so there's still time for this evening's shifts to look at the latest high resolution guidance and make any adjustments accordingly.

Moving into Tuesday itself we should see our temperatures descend with this system, with highs back to near to just above normal and a bit more seasonable overall in the 40's to 50's. While precipitation will linger into the evening, the heaviest accumulations are expected during the morning and early afternoon hours, with locations east of the Laramie Range expected to see mostly rain. If we do get any snow to mix in, it wouldn't be for long and the warm ground temperatures will melt that off fast. We return to sub-freezing lows overnight into Wednesday morning, but by the afternoon the region will be back to well above normal highs as the 50's to 60's return under transient ridging, which will also keep us dry for the mid-week timeframe. This will be brief however, and by the start of the long term forecast period into Thursday look for a more progressive pattern to return.

LONG TERM /THURSDAY THROUGH SUNDAY/

Issued at 221 PM MST Mon Mar 2 2026

In the wake of our system earlier in the week, our area will briefly be under the influence of a shortwave ridge, bringing us well-above average temperatures with a chance for some light precipitation ahead of the next incoming system. High temperatures will likely exceed 60 degrees east of the Laramie Range, with 50s west of the I- 25 corridor. Models actually have some weak instability progged primarily over our Wyoming counties, so any precipitation may be more convective in nature. Lee cyclogenesis will take place on Friday downstream of a vigorous shortwave trough digging across the Four Corners region, with an associated front impacting SE Wyoming and W Nebraska during the day, resulting in a 20-25 degree drop in high temperatures relative to the previous day. For once, our temperatures will actually be cooler than average, so enjoy the brief taste of winter while it lasts. Given our location relative to the vorticity maxima associated with the 500 mb closed low (resulting in differential cyclonic vorticity advection) along with progged 700 mb frontogenesis, we expect that precipitation will be rather widespread and likely in the form of snow given the post- frontal air mass.

As we head into the weekend, we remain in a cold advection regime under northerly flow, resulting in another day of below-average temperatures and blustery conditions. We will be in the left- entrance region of a 110 knot 250 mb jet, therefore large-scale subsidence and dry conditions are expected at this time. On Sunday, 500 mb heights rise as a zonally-oriented ridge (weird, right?) builds on the eastern periphery of a mid-level anticyclone located off the California coast. This should result in a warming trend into early next week, which will also be accompanied by an increase in our winds. 700 mb cross-barrier flow is progged to exceed 50 knots, with supporting guidance from an in-house wind product suggesting greater than 60% probabilities of Arlington meeting high wind criteria. Details will become more apparent as we get closer in time to this event, but generally the trend is towards warmer, drier, and windier conditions after a brief cooldown heading into this weekend (which will hopefully involve some beneficial moisture).

AVIATION /06Z TAFS THROUGH 06Z WEDNESDAY/

Issued at 1045 PM MST Mon Mar 2 2026

A fast moving Pacific storm system will push across the region tonight and Tuesday with rain changing to snow above 6000 feet, and periods of moderate rain across the high plains through much of Tuesday. MVFR and IFR conditions are expected, especially across the southeast Wyoming terminals over the next 12 to 18 hours.

HAZARDS/WEATHER TRENDS: Tricky Aviation forecast for tonight and Tuesday morning with multiple bands of precipitation moving across the area. In addition, expect rain to change over to snow at KRWL and KLAR between 06z and 12z, and around 12z to 15z for KCYS. These terminals have the best chance to see IFR or even LIFR conditions for multiple hours through Tuesday morning. Can't rule out some locally heavy bands of snow with VIS below 1/2 mile between 10z and 18z. Conditions should improve after 20z.

Further east, mostly a rain event for western Nebraska with occasional MVFR to near IFR CIGS starting around sunrise Tuesday morning (13z) for all terminals except KCDR. Can't rule out a brief thunder shower tonight, but not confident enough to add to area TAFs.

CYS WATCHES/WARNINGS/ADVISORIES

WY...Winter Weather Advisory until 5 PM MST Tuesday for WYZ103. Winter Weather Advisory from 11 PM this evening to 5 PM MST Tuesday for WYZ110-116. Winter Weather Advisory until 5 PM MST Tuesday for WYZ112-114. NE...None.