Sunday, February 9, 2014

Positively Cascadian

Before discussing the balmy nature of the weather this morning, here's a very quick rundown of the water totals produced by the storm since 5 AM Thursday based on my eyeball estimates:

Tony Grove Lake (8474 ft): 6.6 inches (Logan Area Mountains)
Ben Lomond Peak (8000 ft): 6.2 inches (Ogden Area Mountains)
Snowbasin Middle Bowl (7400 ft): 3.5 inches (Ogden Area Mountains)
Alta-Collins (9662 ft): 2.3 inches (Salt Lake Area Mountains)

I don't have much faith in any of the automated stations in Big Cottonwood Canyon that measure snow water equivalent, but the Utah Avalanche Center reports 3.21 inches for whatever site they are using (probably manual measurements from one of the resorts), so we will go with that.

The Snowbasin-Middle Bowl and Alta-Collins observing sites are two of the most reliable in the Wasatch and they pretty much tell the tale for this storm.  Temperatures have risen dramatically through the period and are now a Cascade-like 35ºF at Snowbasin Middle Bowl and 27ºF at Alta-Collins.

Thus, we're probably seeing a snow level somewhere near 8000 feet in the central and northern Wasatch and a freezing level near about 8500 feet.  That huge temperature increase means a transition from lower to higher density snow as well as from snow to rain at below 8000 feet during the storm.  Ski conditions today should be "interesting."  Perhaps nobody will care about the Cascadian conditions since beggars can't be choosers.  

One of the interesting aspects of this event is that it has come in waves, despite the fact that the models called for relatively steady precipitation rates.  You can see this in the data from both Snowbasin-Middle Bowl and Alta-Collins.

Clearly we have some work to do to improve our modeling and prediction of these variations in precipitation rate as they are critical for avalanche mitigation efforts along highways at at the resorts and for people like me who are simply hoping to ski when it is snowing the hardest. 


  1. Hi Jim, SNOTEL isn't making it into MesoWest, and the NRCS website appears to be down. Did you find an alternative source for the latest Tony Grove and Ben Lomond obs, or is this a guesstimate based on the non-SNOTEL sites nearby?

    By the way, strong winds and heavy graupel just now on Capitol Hill...

    1. Google tony grove snotel and it will pull up a site that has the data.

      Things getting very convective now. The hits just keep coming...

    2. Hmm... some data seems to be getting through to other sites, but you have to hunt for it. Thanks.

      Lightning strike in Bountiful with the latest band. Based on 12Z obs and forecast soundings, looks like it's moist neutral or weakly unstable all the way up to 450 mb. Imagine if it were cold too.