Thursday, December 2, 2010

KSLC: Another planet

It is remarkable how different the weather can be between the east bench and the Salt Lake International Airport (KSLC) during some inversion events.

At 1530 UTC this morning, it was a balmy 32F at the University of Utah, but a frigid 19F at the airport.

Further, I could spy a thin layer of fog around the airport while running in the avenues foothills this morning.  Fog was first reported at the airport at 0335 UTC and persists thusfar this morning.  The minimum visibility reported was only 1.5 miles (at 1000-1030 UTC), but it is up to 5 miles now.

Soundings from 1200 UTC yesterday and today pretty much tell the tale.  Yesterday (and the previous night) we had abundant mid-level clouds and isothermal conditions extending from the surface almost to 700 mb.

With warm advection aloft overnight, temperatures at 775 mb have climbed several degrees, leading to fully inverted conditions over the valley floor.

Further, with mainly clear skies, conditions were better for radiational cooling and temperatures at KSLC fell more than the previous night.

An interesting paradox with regards to the inversion evolution is that it is colder at KSLC this morning than yesterday morning, but warmer at the University of Utah.  Knowledge of the evolution of inversion structure is critical to microscale forecasting over the valley.

1 comment:

  1. Its interesting how it is so well-mixed from about 800 to 650 mb... this has been showing up in some of the Reno/Elko/SLC soundings last couple of days but not further upwind in the California soundings. I suspect this layer was mixed out due to turbulence from crossing the Sierra Range, which has brought warmer air down to just above the surface.