Wednesday, January 13, 2016

Parade of Storms

The upper-level analysis and satellite imagery over the north Pacific this morning is simply beautiful.  There is a well-consolidated jet with speeds at 250 mb reaching over 75 m/s (150 knots) over the western Pacific with a parade of storms as one moves downstream and eastward across the Pacific Basin.  I've highlighted the position of the upper-level troughs associated with each of these storms with a red line in the image below.

IR satellite imagery and GFS 500-mb height (black contours) and 250-mb wind-speed contours (orange = 60 m/s; red = 75 m/s) at 1200 UTC 13 Jan 2016.
The first of these storms, which in the image above is moving into the western U.S., will come in tonight and looks to be a quick hitter that produces periods of mountain snow through tomorrow morning in the Wasatch Range.

Plumes from the experimental NCAR ensemble suggest that the strongest burst of snow will probably be sometime late tonight or early tomorrow morning at Alta Collins.

The range of water equivalent produced by the ensemble is very large.  One member produces very little precipitation (blue line), whereas the wettest member generates a bit over 0.8".  The latest NAM is going for .23" at Alta through 2 PM tomorrow.  Temperatures are such that this will be lower density snow, at least in those areas it doesn't get trashed by the wind.  Something in the 4-8 inch range for snowfall seems most likely for the upper Cottonwoods through noon tomorrow with some potential to fall a bit above or below that range depending on how productive the storm is in terms of water equivalent and the snow-to-liquid ratio.      

Storm #2 will looks to be a player for Thursday night and Friday.  It looks to be a quick hitter, although it is currently advertised to be a bit larger than this first storm for the Cottonwoods.  We'll see how it holds together.

For storm #3, much depends on storm track.  It could play a role over the weekend, although some model solutions call for it to track to the north with northern Utah getting a brush by.  

All in all, this ain't too bad.  I like small storms every couple of days, although the effects of the winds on avy hazard and snow quality may warrant some attention.  

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