Wednesday, February 29, 2012

Strong Valley Flow

There is a very strong pressure gradient ahead of the approaching cold front that is driving strong southerly along-valley flow in many of the valleys of northern Utah including the Salt Lake and Tooele Valleys.  The strong pressure gradient is evident in the 1800 UTC (1100 MST) sea-level pressure analysis below.
Source: NCAR/RAL
It has been fairly windy in the Salt Lake Valley this morning.  In fact, the wind gusts on the valley floor are nearly as high as at some mountain site.  For example, at 1100 MST, winds at Salt Lake City International Airport were gusting to 43 mph, while at the top of Mount Baldy in upper Little Cottonwood, an extremely exposed ridge-top site, they were only reaching 50 mph.  Looking at the gusts in the map below (red text), you can see a number of valley sites with gusts comparable to or higher than observed at many upper-elevation sites in the Wasatch Mountains (ignore the 59 mph gust in Sandy which appears erroneous).

Source: NOAA/NWS
The crest-level flow will, however, be picking up with the approach of the cold front during the day today, leading to dendrite armageddon, the destruction of the blower pow that fell yesterday, throughout the range.  Fortunately, more snow is coming.  

1 comment:

  1. It is interesting to note that winds have been mostly light and quite variable in Utah County, where temps are a few degrees cooler. Apparently the strong winds are overshooting the mostly closed basin there as often happens in southerly flow, although this seems like a pretty dramatic case. Several sites there even report northerly surface winds, perhaps an eddy-like effect in the lower levels with reverse flow near the surface.