Winter Storm — Rock Springs & Green River, Wyoming

2020-09-07 to 2020-09-08 · Rock Springs & Green River, Wyoming

Event narrative

A tight pressure gradient and strong mid level winds mixed to the surface around Rock Springs and Green River, Wyoming. In addition, up to 7 inches of snow fell on trees that had full foliage. The result was widespread tree damage with large limbs and entire trees downed. At one point, almost the entire city of Green River along with much of Rock Springs, Wyoming was without power. Winds gusted as high as 67 mph in Green River at the height of the storm.

Wider weather episode

An unusually cold air mass dropped southward behind a cold front that moved across Wyoming. The front combined with ample moisture as well as strong mid and upper levels winds to bring an historic early season storm to much of western and central Wyoming. Many areas East of the Continental Divide, especially in the higher elevations and adjacent foothills, saw large amounts of snow. The highest amounts fell in the Wind River Range and Casper Mountain where up to 18 inches of new snow fell. Many areas around Casper and Lander, Wyoming, saw up to a foot of snow. The heavy, wet snow fell on trees with full foliage and brought down branches, limbs and in some cases entire trees. The trees fell on power lines causing numerous power outages. In western and southern Wyoming, wind was the main hazard. The strongest winds occurred in Sweetwater County, with wind gusts as high as 86 mph reported at the Rock Springs airport. Numerous trees were downed in Rock Springs and Green River, leading to thousands losing power. Portions of Teton and Sublette Counties also saw widespread tree damage and loss of power.

Source: NOAA Storm Events Database, event_id 920054. Narrative written by the NWS forecast office that issued the report.