Can Blowing Snow Forecasts Be Significantly Improved across the Rocky Mountain Region and Northern High Plains?

Harsh winter road conditions caused by blowing snow results in travel nightmares across Southern Wyoming for truckers, visitors, and even locals year after year. The United States’ hotspot for blowing snow is southern Wyoming and the adjacent mountains to the south (Colorado Front Range) and north (the Wind River Range and the Absarokas) as well as the immediate lee of these mountains, where downslope windstorms are common. This study will highlight two cases from wind prone areas along Interstates 80 (North Snowy Range Foothills) and 25 (Bordeaux Wind Gap) in southern Wyoming last year where blowing snow created hazardous road conditions. Both cases resulted in visibility reduction below ½ mile, wind gusts exceeding 45 MPH, and highway closures lasting multiple hours due to hazardous road conditions and crashes. Both cases showed their similarities with current snow cover and frigid temperatures, and differences with age of snowfall, cloud cover, and wind speed along with their respective terrain influences.

Blowing snow is very difficult to predict as it depends not just on current snow cover, snowfall, wind speed and turbulence, and temperature, but also on age of the snow, recent history of precipitation, daily maximum temperatures, and insolation. Accurate forecasts of these parameters are critical to the prediction of blowing snow, which is especially more difficult in complex terrain. Current blowing snow forecast technique consists of the Baggaley method, a probabilistic approach which utilizes nomograms to provide blowing snow probabilities based on wind speed, temperature, and snow age. The recently funded CSTAR project Improved operational prediction of blowing and falling snow and extreme wind events in the Rocky Mountain region and northern High Plains will begin to work on improved understanding, prediction, and dissemination of blowing snow events in addition to other high impact winter weather phenomena through collaboration with the University of Wyoming, High-Resolution Rapid Refresh Development Group, and neighboring Weather Forecast Offices.