Sunday, January 8, 2023

Two Storm Week Ahead

Our winter of wonder continues this week with two storms on tap.  

That's not counting todays small appetizer as a weak trough swings through and may give a few snow showers to the Cottonwoods this afternoon.  

The first of the two significant storms develops late Monday and Monday evening as an atmospheric river penetrates through southern California and Nevada to northern Utah (see lower right panel below). 

Monday night and early Tuesday morning look windy and mild.  Our GFS-derived forecast guidance shows peak gusts on Mt. Baldy over just over 70 mph in the early morning hours on Tuesday with the wet-bulb zero level peaking at just over 7000 feet (that would equate to a snow level near 6000 feet).  Water equivalent precipitation from 11 AM Monday to 11 AM Tuesday is 1.12" with 7" of high-density snow.  

The 12Z HRRR run is in and it's not quite as windy (peak gusts near 60 mph), but is is milder, with the wet-bulb zero getting up to just over 8000 feet.  The HRRR only goes through 48 hours, but from 11 AM Monday to 5 AM Tuesday it's putting out 1.32" of water and about 7" of high-density snow.  

The second storm is coming in on the heels of the first and expected to spread into the area on Tuesday night and extend into Wednesday.  This storm looks cooler, with lower snow levels and snow densities more typical of Utah.  After that, we may get a break for a couple of days with mild weather.  The models are not in good agreement for what happens next weekend, so we will need to see how that plays out.  

To summarize, a mild, windy storm is on tap for Monday night through Tuesday morning that will probably put down 5-10" of high density snow at Alta.  Then a cooler storm comes in for Tuesday night and Wednesday.  By and large another good week for snowpack and skiers if you are happy playfully surfing some higher-density snow in the first storm.  

9 comments:

  1. Would you be able to post a link to view an ensemble grid, either gfs or ecmwf or both? I have been trying to find it but no success. Thanks for all you do!

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    1. See weather.utah.edu. NAEFS-Downscaled and SREF-Downscaled in left hand nav bar provide access to ensemble forecasts. Look for LCC Guidance (GFS) and LCC Guidance (HRRR) for Little Cottonwood forecasts derived from those models in the top nav bar.

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  2. I was trying to find your old post about the shortfalls of the powder buoy to explain it to a friend. I dug way back through your archives to no avail. Would you mind pointing me in the right direction? I wanted to give you some work for tomorrow, since it'll be too heavy to tour in. ;)

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    1. I don't recall ever discussing it on the blog and it doesn't come up when I search the site for buoy.

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    2. Ha. I've also been in Reid's position where someone I know has waxed religious about the mythical powder buoy, claiming it to be some type of meteorological cheat code that the experts haven't caught up on...

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    3. Powder Buoy. Great fun but nothing but a marketing shill! I have a t-shirt…

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    4. Thanks for checking into it!

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  3. Not sure I’ve ever seen a SPC marginal risk area for Utah in January…

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  4. This comment has been removed by a blog administrator.

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