textproduct: Western and Central Wyoming

KEY MESSAGES

- Windy southwest winds are expected today, with widespread gusts of 25 to 40 mph. Wind prone locations could see gusts up to 50 mph. Otherwise, afternoon temperatures will be mild across the area.

- Snow chances (70-90%) increase this afternoon across west and northwest Wyoming. Precipitation (rain then snow) spreads east across the entire area midday on Thursday. Strong winds and snow could create hazardous travel conditions Thursday evening through Friday morning, especially along I-25, US 20/26, and US 287.

- There is high confidence (95%+) in a hard freeze (28 degrees or below) Friday morning and Saturday morning. Widespread morning lows in the low 20s and teens are expect on Saturday morning.

UPDATE

Issued at 1257 PM MDT Wed Apr 15 2026

1PM/19Z radar imagery shows light snow showers over the Tetons, indicating that the first push of Pacific moisture, associated with the winter weather system, has arrived. Expect only rain across Jackson Valley and Star Valley this afternoon with temperatures in the 40s. Snowfall rates for the northwest mountains and the Wind River Mountains will increase by 6PM MDT today as the upper level trough begins to push into the Northern Rockies, with moderate to heavy snow expected. Anticipate winter travel conditions across Teton Pass, Togwotee Pass, and South Pass with snow and gusty 30 to 50 mph winds. As for the western valleys, temperatures are forecast to remain above freezing until after midnight tonight. This means that rain will chance over to snow after midnight as well. Expect only light accumulations of 1 to 3 inches for the western valleys through Thursday night.

As mentioned in the morning discussion, precipitation will spread east across the state during the day on Thursday as the potent cold front pushes east. Expect precipitation to begin as rain ahead of the cold front with temperatures in the 50s. On Thursday, the cold front is expected to pass through sometime in the noon to 3PM timeframe for Johnson County and 3PM and 7PM timeframe elsewhere and quickly drop temperatures. Rain will quickly change over to snow due to the quick temperature drop during these timeframes. Also, widespread windy conditions are expected due to the tight temperature gradient both ahead and behind the front. Gusty 30 to 50 mph are forecast for most low elevations. Near and in Buffalo, northerly gusts of 60 mph are possible behind the front Thursday night.

Although snow amounts for Fremont, Natrona, and Johnson Counties are in the generally in the 1 to 5 inch range, Winter Weather Advisories have been issued for these areas due to wind and snow. The gusty 30 to 50 mph winds combined with light snow will no doubt cause reduced visibilities and periods of hazardous travel. Additionally, due to the strong temperature drop with the cold front, and thus increased frontogenesis, convective snow bands/snow squalls are possible across eastern Fremont, Johnson, and Natrona Counties along the front Thursday evening and overnight. This banding could also occur across eastern Sweetwater, including along I-80, but confidence is too low to include this area in the hazard. Any snow squall or convective snow band will cause sudden drops in visibility and create very hazardous travel conditions. Confidence remains very high (95%+) in a hard freeze (28 degrees or less) Friday morning as well. It is necessary to note that Winter Weather Advisories have also been issued for the Bighorns, Casper Mountain, and the Rattlesnake Mountains for the same reasons.

DISCUSSION

Issued at 109 AM MDT Wed Apr 15 2026

For most of the state, the mild temperatures will belie the abrupt and shift weather shift approaching. Most of the state will again see mild temperatures and gusty winds today, with highs in the 60s.

And then the bottom falls out of the forecast. The next winter system is coming ashore along the PacNW this morning, and will already start to spread snowfall into the NW mountains by this afternoon. This snowfall will only increase through the night tonight as the cold air pushes into the state. The main cold front will race across the state during the day Thursday, bringing a stunning drop in temperatures from the low to mid 50s around noon to the upper 30s by 6PM. As the front sweeps through, precipitation will come along as well. Precip will start as rain for the lower elevations briefly, before switching to all snow by early evening. Snow will continue across the state through the night into Friday, continuing through sunset before tapering off. Main forecast issue is how much of the initial snowfall will melt off, due to ground temperatures already being very warm. Putting all these factors together, Have gone ahead and upgraded current Winter WAtches to Winter Storms Warnings for the NW Mountains, including the Wind River Range. Will need to closely monitor the snow forecast for the Bighorns, along with lower elevations of Johnson, Natrona, and Fremont Counties for last minute model shifts for accumulations.

As this system sweeps southeast, skies will gradually clear west to east Friday night. The cold pool moving in behind the system is particularly cold for this time of year, and a couple factors will determine just how cold temperatures fall. First is how fast cloud cover clears out, allowing better radiational cooling. Second is if there's any considerable sfc snowpack insulating the cold pool as it moves through. Current forecast is for lows in the mid to upper teens. with clouds clearing sell before sunrise, and snowpack holding for most areas. Current forecast has temperatures in most lower elevations falling below 28 degrees (hard freeze) for 9 to 12 hours. This will have a significant impact on already flowering plant life, animals, lawn sprinkler and irrigation systems, and the like. Please take any and all precautions for a late-season cold snap.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 1127 AM MDT Wed Apr 15 2026

VFR conditions across nearly all terminals to start the TAF period. KJAC is the only exception as showers begin to move into the area leading to lowered ceilings and MVFR conditions. A nearing disturbance will bring rounds of precipitation to western terminals and increased winds to nearly all terminals this TAF period. KJAC as mentioned earlier will see showers through the afternoon into the evening. There may be some spotty showers after 02Z Thursday with another round of precipitation likely by 09Z. By this time temperatures should drop to near or below freezing leading to snow showers. Otherwise, winds increase for the start of the period at nearly all terminals with gusts of 20 to 35 knots possible through the evening. Winds decrease slightly after sunset with breezy winds of 10 to 20 knots persisting through the overnight. A cold front begins to enter the state Thursday morning which will bring precipitation chances to KCOD, KPNA, KBPI, and KJAC around the end of the TAF period. Winds will start to increase ahead of the frontal passage with many terminals seeing winds increase by around 15Z Thursday. Aside from increasing winds all terminals will likely see lowering ceilings around this time. Mountain obscuration will be persistent through the TAF period especially across western mountains with obscuration increasing by the end of the TAF period.

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

Winter Storm Warning from 6 PM this evening to 6 AM MDT Friday for WYZ001-002-012.

Winter Weather Advisory from 9 AM Thursday to 6 AM MDT Friday for WYZ008-009.

Winter Weather Advisory from noon Thursday to 6 AM MDT Friday for WYZ010-011.

Winter Storm Warning from 6 PM this evening to 6 PM MDT Friday for WYZ014-015.

Winter Weather Advisory from 3 PM Thursday to 6 AM MDT Friday for WYZ016>018.

Winter Weather Advisory from 3 PM Thursday to noon MDT Friday for WYZ019-020-022.