Sunday, November 26, 2023

A Sea of Stratus

It's pretty rare that stratus clouds, which otherwise are a zero on a meteorological scale of 1 to 10, can make for a great weather day, but they did today.  

Morning dawned in the Salt Lake Valley with dreary, grey overcast in the form of stratus clouds covering the entire sky (the image below taken looking south from the U at 8:12 AM).  However, a look toward the Cottonwoods showed a brighter spot, suggesting that perhaps there was hope for sun at high elevations.  

Source: University of Utah Department of Atmospheric Sciences

Sure enough, the Alta webcam showed clear skies above a Sea of Stratus over the Salt Lake Valley.  

Source: Alta Ski Area

And the morning satellite loop was really quite incredible with snow capped mountains, especially the central Wasatch, Southern Wasatch, and Uinta Mountains, sticking up above the Stratus Sea.  

Source: College of DuPage

And, as we started out ski tour from Alta at 9:52 AM, skies were clear, although stratus clouds hung in the central canyon.  

It's not uncommon for such clouds to work their way up the canyon during the day.  This is a result of thermally forced circulations.  Nocturnal cooling favors down canyon at night and in the early morning, which sometimes keeps the upper and middle canyon cloud free.  Then daytime heating results in up canyon flow with the stratus pushing up the canyon.  Indeed, when we returned to the car at 12:56 PM, shallow but thin clouds had made it to the Albion base area.

The cool thing about this was that there were just enough ice crystals around (some natural, but perhaps some artificial) for a nice atmospheric optics display with a 22 degree halo, sun dogs, and, if you squint, evidence of what is known as a parhelic circle cutting across the sun and through the sun dogs.  

When I lived in Innsbruck, such weather was common.  The meteorologists called the low clouds valley stratus.  Such clouds often filled the deeply incised valleys of the Alps, but spectacular weather prevailed above them at mid and high elevations.  I learned quickly to check the web cams to see if you could get above the clouds.  

That was definitely the case today, and we enjoyed spectacular views from the Supreme Area.  

We need more snow.  Think, pray, whatever. 

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