A pattern change is expected to bring precipitation to Utah beginning Saturday or Saturday night, according to a November 11 report from Wasatch Weather Weenies. Although dry weather is expected to continue through Friday, an upper-level ridge is currently influencing the region as a digging trough moves into the western United States.
The forecast shows an ECMWF HRES forecast valid for 0800 MST Saturday, November 14, illustrating the upcoming change. While the trough is expected to track far enough north to provide precipitation to Utah, the overall pattern involves a split flow along the west coast and strong flow across the US southwest. This split nature contributes to forecast uncertainty over the next 10 days, as water equivalent and snowfall amounts vary depending on the track and intensity of three major upper-level troughs and storms expected to move through the west through November 21.
The Utah Snow Ensemble Forecast for the Alta-Collins area is noted as being among the most optimistic seen so far this season. In this forecast, 90% of members produce at least 1.88 inches of water equivalent and 24 inches of snow through 0000 UTC November 21. However, there is disagreement regarding the first storm, with some members predicting scant amounts while others predict over 15 inches. The track of the storm on Saturday and Saturday night will be a significant factor.
As storms begin rolling in, the median wet-bulb 0.5°C height, a proxy for snow level, is at or below 8000 feet. Officials warned that if snow occurs, avalanche and other hidden hazards such as rocks, tree limbs, and stumps may be present under the fresh snow.
Jim Steenburgh, a Professor of Atmospheric Sciences at the University of Utah specializing in mountain weather and climate, authored the report. The Wasatch Weather Weenies blog examines weather, climate, and snow for the Wasatch Front, Wasatch Mountains, and western North America.
