Bad day to be a storm

TL;DR:

Snow has started in the mountains. Expect this snow to continue through Wednesday as we get a steady stream of moisture from a storm off the west coast. No extremely heavy precipitation windows, but the overall totals could be substantial. I expect 20-30 in the mountains and 4-6 in the valley. 

Nowcast:

Snow has started falling at the resorts. It's a brisk morning with trailheads/bases sitting in the '20s and ridgelines in the '10s. The winds are relatively weak. 

Short-term: 

Large-scale setup (2/27/23 13:50:21 UTC). Courtesy: College of DuPage

Above is the upper-level water vapor channel on board GOES-West. The storm that will be providing us with more snow can be seen just off the coast of Oregon. The comma cloud stretches over Washington, Oregon, and Northern California. The GFS has this storm slamming into the west coast over Oregon and Northern California, after which it will make its way into Utah. 

Right now, the GFS and HRRR agree that there will be two "waves" of the storm. I don't want to call them fronts because they don't look like very organized fronts, at least to me. The first wave of the storm has just started and should continue through tomorrow morning. Substantial mountain accumulation is likely tonight. The Little Cottonwood GFS Guidance says just over 15 inches by midday tomorrow. The HRRR is suggesting a little less (12 inches). A foot is a safe bet, with more if it really gets going. 

There will be a break on Tuesday, and then the second wave comes in. It's going to start Tuesday night/early Wednesday morning. There should also be another 15 inches or so associated with this one. Take a peak at the SREF ensemble below.

Courtesy: UofU ATMOS

The ensembles are relatively tightly packed, around 30 inches or just under for this storm. The outliers are evenly distributed above and below the mean, so we'll have to see how it shapes out. I'd say 25-30 inches is a safe bet. 

It just keeps coming. 

Long-term:

After this storm, the GFS quiets down until later next week, where there is real potential for another big one if it shapes up. The Euro doesn't show a similar setup at the end of the run, but neither option looks too bad. I'm going to focus on skiing the powder that's in front of me. 

Have a good week out there y'all. If you're planning to venture into the backcountry, please check out what our friends at the UAC have to say.