Quite a mess of a storm right now over northern Utah. I'm not sure where to start, but maybe a look at some of the observations is a good place.
Easterly flow extends from southwest Wyoming to the northern Wasatch Front where strong downslope winds persist from the area around Parleys Canyon northward. One can also find strong easterlies in local canyons further south, such as Provo Canyon. In the western Salt Lake Valley and along the US-40 in the Wasatch Back, the flow is northerly. The former reflects what we sometimes call the "Sandy Eddy", a counterclockwise circulation that often forms over the Salt Lake Valley during downslope windstorms and is centered near Sandy.
A look at the flow on Hidden Peak and Mount Baldy in the central Wasatch, however, shows southerly flow. Indeed, the sounding from the Salt Lake City airport this morning is simply amazing.
The surface flow out at the surface was actually light and from the northwest, with a layer of strong easterlies between about 800 and 750 mb. This might seem odd, but often during downslope windstorms there is a hydraulic jump downstream of the mountains where the strong easterly flow becomes elevated, with a rotor beneath with reversed flow at the surface.
|Source: Whiteman (2000)|
|College of DuPage|
Finally, if we turn to radar, we see that each of those bands is associated with precipitation.