Cowboy State Daily - Wyoming News

News

Headlines

View all

Daily Features

View all
Sunrise 3 18 24
PinYour Wyoming Sunrise: Tuesday, March 19, 2024

Today's Wyoming sunrise was captured by Don Crank at the Seedskadee National Wildlife Refuge. Don writes, "Just an awesome morning to catch the sun coming up on the Green River."

Photo by Don Crank

Today's question to Don Day

Wayne Sibilia of Pinedale
I'm curious how the terrain in the Pinedale seems to respond totally different to winter storms and the resulting snow amounts when arriving from the west or southwest? When compared to areas like Bondurant, the Hoback Canyon, Hoback Ranches or the Star Valley, we've gotten very little to no snow while our surrounding areas have been dumped on. The storms this winter seem to have almost totally bypassed the Pinedale area and yet our neighbors to our north, east and west have all received much heavier snow amounts. What causes the snow to almost totally skirt this area? And almost all the NWS predicted snow events so far this winter have totally missed their marks.
Don Day
Wayne - Your observation is a good one in regards to understanding that terrain plays a huge role in how snow falls across Wyoming. The two largest basins in Wyoming, the Upper Green River Basin and the Big Horn Basin are the two areas where it is hardest to get snow to fall. The reason, the terrain/topography and its relation to wind direction. The Upper Green River basin is bounded by the Wind River Mountains to the east and the Wyoming Range and Salt River Range to the west. With large winter storms it is common for storms to bring easterly winds (wind from the easterly directions) or when Pacific storms come in the from the west-northwest (wind from the W-NW direction). In the easterly wind situation, the wind has to climb up the Wind River Mountains which in turn causes the heaviest snow to fall on the east side of the range and communities along the eastern slopes (ie,Lander). As air is forced to rise over terrain, it cools and will condense the moisture in the air. This results in clouds/snow. However, as the air comes over the divide and into the Upper Green River Basin, it sinks coming down the west side of the range. Sinking air causes the humidity to drop and temperatures rise, in turn that eliminates or greatly reduces snowfall amounts. The situation is similar when Pacific storms come in from the W-NW. The mountains to the west catch the snow on the windward sides of the ranges (Gros Ventre, Salt and Wyoming Ranges) and the sinking air moves into the Upper Green River Basin. For the Pinedale/Daniel/Boulder/Cora areas to receive "big snow" you need a storm to direct wind flow in from the SSW where the terrain is lower upstream and the winds can rise on the west side of the Wind River Range. This happens most frequently when you get a large, slow moving storms that will move into NV then UT. If storms track north or south of those areas, the heavier snow will go around you. The Big Horn Basin is in a similar situation with the Absarokas, Owl Creek and Big Horn Mountains having a big influence.
DD

Newsletter