textproduct: Western and Central Wyoming

KEY MESSAGES

- A potent late winter storm will sweep across Wyoming through the rest of the week, bringing widespread snowfall to most of the state. Winter Storm Warnings are in effect for the northwest mountains tonight through Friday.

- Cold air moves in with the winter storm, with temperatures likely falling below 28 degrees both Friday morning and Saturday morning (90% +). Extent of temperatures below freezing could reach 12 to 15 hours Friday night into Saturday morning.

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 /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 359 AM MDT Wed Apr 15 2026

VFR conditions should continue through around 20Z for all terminals. An approaching area of low pressure will begin to spread showers into the western mountains this afternoon, with showers possible in vicinity of KJAC starting around 20Z. Precipitation should begin as rain, then transition to snow tonight as colder air moves in behind a cold front. Other showers spread into KPNA and KBPI later tonight. Almost all showers should hold off until after 12Z Thursday in the terminals East of the Divide. Mountain obscurations will be common later today and tonight to the west of the Continental Divide.

Wind will increase at all terminals this morning as the low approaches the area. The strongest wind will occur in vicinity of KCPR and KRKS where gusts to over 35 knots will be possible after 18Z. Wind should decrease somewhat at most terminals after sunset but remain strong in vicinity of KCPR through most of the night.

RIW WATCHES/WARNINGS/ADVISORIES

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

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