TL; DR: A low pressure system will travel through Utah and bring several more inches of snow to ski resorts. The expected storm system would also help clean up the haze and smog in the valley and give you a nice snow scene during Christmas. Enjoy the powder gift from mother nature.
Nowcast: The models show the upper-level ridge has flattened this morning, and the pressure gradient has started increasing across the state out ahead of the next storm system. Winds and cloud coverage will increase throughout the day, but the dry air mass in place will hold off any precipitation until Thursday.
Short term: The global ensembles show a cold and moist air mass is moving toward Utah. This North pacific mid-latitude trough will pass through the western US over the next couple days. Snow will likely start falling around Thursday midday and continue through Friday night.The snow-to-liquid ratio (SLR) will start off at about 10:1 and increase to near 15:1 over the duration of the event as temperatures cool and the trough axis moves closer to the state. We’re expecting 1-2 feet of snow in the northern mountains and 6-12 inches across the southern mountains. In general, the dynamics of this storm are reliant on the support of the 150 knot jet and so most precipitation will be orographically enhanced. Resorts like Deer Valley, Sundance, Brighton, and Solitude are the most likely to overperform these projected totals.
Long term: After a short break in the snow on Saturday, multiple short waves embedded within a deeper Pacific trough are expected to bring snow storms from Sunday into the early part of next week. The snowfall totals in the ski resorts are uncertain now, but the snow is expected throughout the week.
As usual, If you are venturing into the backcountry refer to The Utah Avalanche Center for a full avalanche forecast for your local mountains.
Additionally see the Utah Department of Transportation for road and travel information.