A Cool, Dusty Spring?

A lot of people have commented to me that it has seemed lie a cool spring, however, the numbers tell another story.  

At the Salt Lake City International Airport, the average temperature from April 1 to May 9 was 51.9˚F.  This is a bit cooler than we have seen since 2013, but tied for 58 out of 148 comparable periods since 1875.  

Source: NOAA Regional Climate Centers

That's not unusually warm, but it is above the median for the entire period of record.  

We have had a few upper-elevation snowfall events, but these haven't been able to counter melt losses except in the highest elevations.  Basin wide, the Jordan shows a sawtooth-like decline since late March with water equivalent increases during snowy periods interspersed with declines during intervening dry periods.  The basin-wide average now sits at 5.2 inches, or 63% of median for the date.  

Source: NRCS

Still, the episodic snowfall events have enabled some good upper-elevation skiing.  I suspect yesterday morning was a lot of fun if you got out.  

Meanwhile, we've seen several wind-blown dust events.  PM2.5 observations from the University of Utah over the past 30 days show several extended periods of slightly elevated PM2.5 (say 2.5 to 7.5 ug/m3) and then briefer but dirtier spikes to higher values associated with the passage of fronts or other boundaries.  

Has this year been exceptional from a dust perspective?  I don't know the answer to that.  Dust storms are not unusual in our region during the spring.  I've written about them since the inception of this blog (see https://wasatchweatherweenies.blogspot.com/search/label/Dust), including events much stronger than anything we have seen this year (e.g., Postfrontal Dustpocalypse and Black Tuesday Becomes White Wednesday).  

Dust storms exhibit a great deal of year-to-year variability due to meteorology and land-surface conditions.  The bed of the shrinking Great Salt Lake is an emerging dust source, but there are many sources in the Great Basin, some of which have waxed and waned over the years.  For a while, the Milford Flat Fire scar was a big producer, but that seems to not be the case anymore. Agricultural fields west of Utah Lake were big producers a few years ago, but don't seem to have been exceptionally active this year.  Some of the dust we've been seeing this year in northwesterly flow has originated over northern Nevada, so it's not all from the Great Salt Lake.  

It will take someone smarter than me to place this spring into a long-term context and perhaps try to identify key sources.  My anecdotal view is that we've seen more low-intensity dust events this year than in the past several years, but the high-intensity events haven't been as intense.  That's an anecdotal perspective, however, subject to change with additional information.