Sunday, June 19, 2011

Father's Day Lake- and Playa-Effect?

Mother Nature will not give us a break.  A well-advertised dousing is underway this morning as yet another upper-level trough moves through northern Utah.  The NAM-model analysis for 1200 UTC (0600 MST) this morning shows the uper-level trough axis just upstream of northern Utah with 700-mb temperatures of 1C over Salt Lake and less than 0C just upstream.

The latest regional radar shows that the heaviest precipitation is falling over and downstream of the Great Salt Lake and over and downstream of the Salt Flats to the west.

Source: NCAR/RAL
More frequent and intense convection over these two areas is quite evident in the KMTX radar loop from 1237–1453 UTC.

Is this simply a reflection of the larger-scale environment, or are the lake surface and salt playa contributing through locally enhanced surface heat and moisture fluxes?  

In the case of the Great Salt Lake, the latest MODIS derived lake-surface temperatures from yesterday were quite balmy and in the 18-22C range.  It certainly seems plausible that the lake is juicing things today.

In the case of the Salt Flats, playa has a very large thermal inertia compared to the surrounding land surface.  In other words, its temperature changes more slowly.  Further, it can sometimes be covered, especially in a year like this, with a thin lens of water, which would be quite warm due to yesterday's warm temperatures.  These two factors could be contributing to locally high heat and moisture fluxes over the Salt Flats.

So, perhaps we have lake- and playa-effect (or at least enhancement) occurring today.  

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