Thursday, April 21, 2016

Is Our Nearly Snirt Free Spring Coming to an End?

As far as dust storms go, this past cool season has been pretty quiet.  We've had a few minor events, but nothing significant, and the Wasatch snow cover remains fairly white and relatively snirt free (snirt = part snow part dirt, the dirt meaning dust).

The lack of dust so late into the spring is fairly unusual.  Estimates of total dust flux at the Salt Lake City international airport show a pronounced peak in April.
Source: Steenburgh et al. (2012)
What's been missing this year are strong south wind events that can tap into dust emission sources in southwest Utah.  We simply haven't had them, but that's about to change.

With the approach of an upper-level trough, we will see the development of south winds tomorrow.  The 1200 UTC NAM forecast valid at 0000 UTC 23 April (6 PM MDT Friday Afternoon) shows the upper-level trough over northern California with 30–40 knot SSW 700 mb (10,000 ft) winds and 15–25 knot SSW surface winds over western Utah.

The situation is not quite ideal for a strong wind-driven dust event as the surface trough is not especially deep and the surface front is still over eastern Nevada (ideally we want the front moving into northern Utah late in the afternoon), but it is the first event we've had this spring with the potential to stir things up.  We'll have to see tomorrow if the winds are strong enough and if the land-surface is ready for dust emissions.  I prefer my corn white, so I'm hoping that's not the case.

Oh, and in case you are wondering, some cream on crust is looking likely for the mountains on Saturday.

1 comment:

  1. In the absence of natural dust, it seems like there is plenty of man-made explosive residue accumulated from a season's worth of bombing routes. During the last major melt event it looked like Alta's mascara was running.