The large-scale pattern for the past several days has featured an active polar jet over the north Pacific and an active subtropical jet across the subtropical eastern Pacific, Mexico, and the southern tier of the U.S. Upper-level troughs have been exiting the polar jet, digging southeastward across the western US, and then merging with the subtropical jet over the southwest US.
On Saturday morning, the upper-level trough that barely missed Utah and wreaked havoc on the PGA tournament in Tucson on Thursday, was over west Texas and was being carried downstream to wreak havoc on the eastern U.S. by the subtropical jet. The upper-level trough that produced our sublime weekend of powder skiing was over the Pacific Northwest and posed to move into Utah.
This morning, it is nearly deja vu all over again. The upper-level trough that gave us our weekend powder dug southeastward and merged with the subtropical jet over west Texas. Another upper-level trough is moving over the Pacific Northwest and is poised to move into Utah.
So, another foot plus dump for the Cottonwoods? Well, there was a reason why I said nearly deja vu all over again. Although the pattern is similar, there are some subtle but important differences. First, the upper-level trough over the Pacific Northwest this morning is not as strong as the one that affected us this weekend. Second, the pattern upstream is somewhat different this morning (Saturday featured a very strong explosively deepening storm in the western Aleutian Islands that helped further amplify the approaching trough). Third, the plume of moisture with the upper-level trough over the Pacific Northwest this morning is not quite as juicy as Saturday's Soy Sauce Express.
As a result, the models are calling for snow, but not as much as in the weekend storm. The latest NAM, for example, is calling for 0.21 inches of snow-water equivalent and 4.5 inches of snow for upper Little Cottonwood. This is about half of what it was putting out for the weekend storm.
So, a bit of a refill tonight and tomorrow morning, but like a drink in Utah, it will likely be metered a bit more than the weekend storm. The light powder should be a great frosting for backcountry skiing.