Batten the Hatches

TL;DR:

To quote the NWS Salt Lake City, "this will be one of the most impactful winter storms of the season." Heavy snow begins today and will persist through Thursday with excellent skiing conditions setting up for the latter half of the work week.

Current Conditions

Pre-Frontal conditions have made their way to the Wasatch with warmer temperatures and light precipitation expected through the early afternoon. Temperatures range from 32F near the base of Park City (7000') to 27F near the base of Alta (8700') to 19F at the top of Mount Baldy (11000'). Winds are generally from the SW at 10mph gusting to 20mph at mid-elevations and 25 mph gusting to 40mph at upper elevations. Alta has picked up 2 inches as of 11am MST.

Light precipitation starting in the Central Wasatch. Image courtesy of Alta Ski Area.

Short Term Forecast

A deepening upper-level trough is digging south through the Western United States associated with a decaying Atmospheric River. A strong cold frontal passage will be moving through Northern Utah Tuesday Afternoon sometime between 2-4pm in Salt Lake County. The heaviest precipitation rates will be following this frontal passage later in the evening. The plot below shows temperatures at the 700mb level (roughly 11,000' elevation) with the red contours. Note the tightly packed contours over NW Utah, indicative of strong cold air advection at this level.

GFS 700mb temperature (red contours), relative humidity (brown/green shading), and wind barbs valid 2300 MST Tuesday, Feb 21. Image courtesy of the Department of Atmospheric Sciences, University of Utah.

Precipitation rates will be high after the frontal passage. The plot below from the SREF Ensemble for Alta shows snowfall rates peaking around 8pm MST Tuesday. The horizontal red line near the middle of each purple rectangle is the median 3hr snow for each time period. The peak snowfall rates will likely be near 2 inches per hour at upper elevations for several hours this evening and into the night. Expect road weather delays and potential road closures due to avalanche concerns. 

3-hour snowfall rates and densities from the Short-Range Ensemble Forecast (SREF). Image courtesy of the Department of Atmospheric Sciences, University of Utah.

Snow Forecast through Thursday Night

Upper Little Cottonwood Canyon (Alta/Snowbird) - 28-36 inches

Upper Big Cottonwood Canyon (Brighton/Solitude) - 24-32 inches

Wasatch Back (Park City/Deer Valley) - 24-32 inches

Park City/Deer Valley Bases - 10-16 inches

Long Term Forecast

Snow will taper off Thursday afternoon. A series of weak systems (think 2-4 inches of snow for Alta) are expected Friday and Sunday before more significant precipitation returns early next week. Unsettled weather will continue through the end of the month and the Climate Prediction Center continues to note the potential for significant precipitation during the first week of March. Stay tuned for more details on these upcoming systems.