Saturday, March 31, 2012

Hot and Dusty

Looks like a hot and dusty day is in store for today.  The day has dawned with a mostly clear, remarkably dry airmass in place over the Intermountain West.

Source: NCAR/RAL
The NAM time-height section for Salt Lake City (time increases to the left) shows dry air (relative humidity < 30%) aloft and in the lower troposphere (<70%, including near 30% at the surface).  

NAM relative humidity (color fill), wind, and equivalent potential
temperature analysis (contours)
Actual surface relative humidities will likely be even lower than indicated by the NAM.  And, the NAM forecast for this afternoon shows strong southwesterly flow over Utah.

All of this adds up to a hot dusty day.  Hot in this instance is relative to climatology.  The all-time record high for March is 78ºF and we'll make a run at that today.  I think something close to that is likely.  Some have called for a high in the 80s.  While that's not impossible, I think it's not likely as the airmass is not that warm.  

Dust?  Yup, it's pretty likely.  The flow is coming from the primary source regions for dust in Utah (West Desert, Sevier Desert, Escalante Desert, and Milford Valley in western and southwestern Utah) and is certainly strong enough to support emissions and transport if the surface conditions are favorable.  

Hopefully clear skies will persist through this afternoon so we can get a good look at any plumes that form.  

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