textproduct: Western and Central Wyoming

KEY MESSAGES

- Elevated to critical fire weather conditions continue this afternoon for much of central and southern Wyoming. A Red Flag Warning is in effect for the lower elevations of Natrona County through 5 PM.

- Precipitation chances return Sunday morning west of the Continental Divide. This is expected to bring light snowfall to the mountains with accumulations of 1 to 6 inches through Sunday evening.

- Monday will see another round of light mountain snow, as well as lower elevation rain chances on both sides of the Divide.

- Above normal temperatures persist through the week, with the next chance for widespread precipitation coming Wednesday night and Thursday.

UPDATE

Issued at 1137 AM MST Sat Feb 28 2026

The forecast remains on track today, with another afternoon of favorable fire weather conditions. With wind a little lighter than yesterday, the area of greatest concern is more limited, mainly focused across Natrona County. Otherwise, satellite imagery shows tonight's system approaching from the Great Basin, with high clouds now beginning to filter into Wyoming. This will bring a shot of moisture west of the Continental Divide starting as early as tonight, though most of the appreciable moisture will hold off until late Sunday morning. As noted below, this will be focused over the western mountains, which are favored to pick up a few inches of snow through Sunday evening.

DISCUSSION

Issued at 144 AM MST Sat Feb 28 2026

08Z surface observations indicate that a northwest/southeast oriented surface boundary is roughly located across the northeast corner of Wyoming. Winds west of the boundary have a westerly component whereas winds east are more northeasterly. Aloft, unsaturated northwest flow continues to dominate the Intermountain West with an upper ridge over the west coast and a broad trough to the east. Upper level winds are not expected to be as strong as they were the past few days, with mean speeds generally in the 70kt to 90kt range. Nonetheless, a somewhat tight surface pressure gradient remains so another breezy day is in store, mainly across the Wind Corridor. Expect afternoon wind gusts of 20 to 30 mph and potentially up to 35 mph across higher terrain. Breezy winds, mostly sunny skies, and warm 700mb temperatures (0C to -5C) will favor temperatures being comparable to Friday (40s across the west and 50s elsewhere).

These breezy winds, above normal temperatures, and dry conditions brings another day of elevated to critical fire weather conditions to the central and southern Wyoming. The area of greatest concern today is focused to lower elevations of Natrona County, where there is a 70%-90% of relative humidity values below 20% and a 40%-50% chance of values below 15%. Although Red Flag Conditions (RH less than 15% and wind gusts greater than 25 mph) are more marginal for low elevations of Natrona County, a Red Flag Warning has been issued from 11AM MST to 5PM MST today. The factors that pushed us to issue the Red Flag Warning are that it has been very dry and windy the past few days, so should a fire start it will be able to spread quickly. It is important to note that across the Wind River Basin, relative humidities are forecast to be 15%-20%, but winds are expected to remain light so no headlines were issued there. Elevated to critical fire weather conditions will quickly diminish after 5PM today as the overall pattern begins to shift.

By late this afternoon, the ridge will have made an eastward shift and "flattened". This will weaken the pressure gradient and allow the aforementioned surface boundary to drift into central Wyoming and position itself along the Continental Divide. Additionally, zonal flow will begin to set up over the state and allow for the return of Pacific moisture to portions of the area. By Sunday, deep available moisture will largely be confined to areas west of the Continental Divide due to the surface boundary remaining along the Divide. This moisture combined with a passing shortwave disturbance aloft will support western mountain snow chances (60%-80%) for Sunday. This is not looking to be a notable snow event by any means. Through late Sunday night, there is a 70% chance of at least 3 inches of snow and only a 20% chance for 6 inches or more of snow for the western mountains.

There is good agreement among both deterministic and ensemble guidance that an upper level trough with an associated closed low will be located over the Great Basin by Monday. This will finally allow that surface boundary to fizzle out and push Pacific moisture east of the Divide. So on Monday, precipitation chances (40%-80%) become much more widespread over the area. Temperatures are still expected to remain well above normal so rain is forecast for low elevation areas. Snow amounts for the mountains on Monday are even less notable than Sunday with only a 40% chance of 3 inches or more. The closed low is forecast to traverse east along or just south of the southern Wyoming border late Monday into Tuesday. As it ejects east into the central CONUS Tuesday afternoon, it will take the Pacific moisture with it. This means to expect overall dry weather Tuesday afternoon and Tuesday night.

A more potent weather system looks to develop as early as Wednesday afternoon as a longwave trough moves onshore the Pacific Northwest and eventually into the Intermountain West. An associated cold front will traverse Wyoming as the trough moves east. Because of the Pacific origin of this system, there will be plenty of available moisture. As of right now, it looks like the system will push across the Intermountain West on Thursday and bring widespread snow and rain chances. Snow is expected across the mountains. However, the current forecast has rain transitioning to snow behind the cold front for low elevations. However, don't get too excited if you like snow as there is only up to a 30% chance of 2 inches of snow. There will inevitably be changes to the forecast given we are still over 5 days out, but it is something that we will need to keep an eye on.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 1005 AM MST Sat Feb 28 2026

West of the Divide...KBPI/KJAC/KPNA/KRKS Terminals.

VFR conditions today, with increasing high clouds. Light winds tonight, with continued increasing clouds ahead of the next, weak weather system. Precipitation chances move into KJAC as early as 14z/Sun, with a 30 percent chance for a rain or rain/snow mix through the end of the period, but better chances for rain after the period, for Sunday afternoon. Chances are only 15 percent at KBPI, KPNA, and KRKS from about 13z to the end of the period.

East of the Divide...KCOD/KCPR/KLND/KRIW/KWRL Terminals.

VFR conditions through the period. Clouds will be increasing through the period as a weak weather system moves through. Any precipitation should be confined along and west of the Continental Divide. Otherwise, winds are diurnal, with increasing gusts for KCPR and KRKS during the afternoon.

Please see the Aviation Weather Center and/or CWSU ZDV and ZLC for the latest information on icing and turbulence forecasts.

RIW WATCHES/WARNINGS/ADVISORIES

Red Flag Warning until 5 PM MST this afternoon for WYZ280.