Saturday, April 20, 2013

Orographic Effects

This morning's radar loops shows the dramatic influence that the mountains of northern Utah can have on winter storms.  Note the persistent radar echoes that are produced over and upstream of the Stansbury and Oquirrh Mountains (identified by red boxes in the radar loop below) as the northwesterly flow is forced upwards by those mountain ranges.

Things are a little more complicated over the Salt Lake Valley and central Wasatch Mountains (ugly oval above).  Here, precipitation develops over the southeast corner of the Great Salt Lake, well upstream of the initial mountain slope.  Lake-effect?  Perhaps.  The contrast in lake and air temperature right now is marginal for lake effect, but it is a juicy airmass, so perhaps it's enough to do the job.  Another possibility is that the funneling of air into the Salt Lake Valley due to the terrain concavity formed by the Stansbury, Oquirrh, and Wasatch Mountains is doing the job.

In any event, it's a nice rainy day out there with snow falling in the mountains.  Enjoy it while it lasts.  You'll be wishing for a day like this in July.

1 comment:

  1. Jim thanks for posting all the radar loops, really drives the point home. Just returned from a skin and ski at Snowbasin. Top of the JP lift at 8840 MSL had almost 10" new in the last 24 hours and it was still snowing hard. Felt like the 10-12% density cream we experience in the northern Wasatch. Of course the sun was out at the bottom, 6410 MSL making for soft and sloppy snow. It has been a fun April! Thanks again Ron Gleason