Friday, September 12, 2014

Canyon Winds

Our first canyon wind event of the season is underway this morning.  Unlike big downslope wind events that typically roar along much of the northern Wasatch Front, this morning stronger winds are confined to a few locals including near Weber Canyon (currently gusting to 36 mph in the canyon) and near Centerville (25 mph).

Wind and wind gust observations within one hour of 14:47 UTC (8:47 MDT).  Source: MesoWest.
There are also east winds on the University of Utah Campus and Parley's Canyon.

Wind and wind gust observations within one hour of 14:47 UTC (8:47 MDT).  Source: MesoWest.
The winds at Parley's Canyon increased at a very gradual rate overnight.  The peak gust of 49 mph occurred early this morning.

The cause of these canyons winds is an area of high pressure that slid down the east side of the Rockies and is currently centered in northwest Nebraska.  The resulting pressure gradient is driving easterly flow into northern Utah.

This easterly flow is, however, very shallow.  By the time one gets up to 700-mb (10,000 ft), the flow over the northwest portion of the state is northwesterly.

As a result, this event is confined to some of the deeper canyons (e.g., Weber, Parleys) and areas where the Wasatch Crest to the east is relatively low (e.g., the University of Utah).

The key ingredient missing from this event and preventing it from being a big, widespread downslope windstorm is a closed upper-level low centered near Las Vegas.  Such an upper-level low is needed to drive easterly flow at mountain-top level.

These east winds should slacken later this morning.  


  1. The 10K ft break in wind direction also apparently corresponds to a break in airmass (I assume, but I'm just an amateur meteorologist--heavy, cold air sliding in underneath?).

    Case in point: In Colorado Springs this morning it was snowing while up on Pike's Peak it was not. The 10K ft. break was visible in the cloud tops from above.


    1. Yes, in the Denver sounding the top of the cold air lies very near 10,000 feet. This is a pretty common situation when there are cold-air intrusions on the east side of the Rockies.