Friday, October 23, 2020

Flakes for Salt Lake City?

This weekends storm looks to be "meh" like the last, although we might see a few flakes in Salt Lake City.  

The models agree on a cold frontal passage through northern Utah on Saturday with some precipitation in it's wake eventually moving in late Saturday or Saturday night, but there are differences in the timing and amount of precipitation depending on the track and intensity of the upper-level trough.  As things stand now, this looks to be a "central Wasatch skipper" with the odds and amount of precipitation greater in the mountains to the north, south, and east, as illustrated by our downscaled SREF product below, covering the period ending 0000 UTC 27 November (6 PM Monday).    


I'd be perfectly fine with this storm skipping us and going to Colorado as they could use the fire-fighting assistance and a small storm will do us no good for skiing at this stage.  

In terms of snowfall, odds of more than an inch are about 50-60% in the upper elevations of the central Wasatch and > 90% in the upper elevations of the western Uintas.  Odds are also > 60% in high elevation areas of central, southern, and eastern Utah.

However, the odds of > 6" are low (<10%) in northwest Utah including the Wasatch Range.  In high-elevation areas of southern Utah, there are modest odds of > 6" and some slim chances of a significant storm.  

At Alta-Collins, the downscale SREF shows a trace to 3 inches of snow being produced by 25 of the 26 ensemble members, some generating that snow with the cold frontal passage on Saturday, others lateron Sunday.  One member has some late snow showers on Monday.  In any event, these numbers are fairly paltry and only one member approaches 5 inches.  No reason to get excited, said the joker to the thief.  

A wider range of possibilities is possible to the south.  For instance, at 10,000 feet on the Manti Skyline, there are SREF members that produce trace amounts, but others that generate 7.5 to 17".  It turns out that low-snow members are those using one model formulation (the "NMB), whereas the high-snow members use another (the "ARW").   

I suspect we'll see convergence around a solution in one of the forthcoming model cycles, so if you are planning to recreate in this area on Sunday or Monday, be sure to catch an update and monitor NWS forecasts, but be aware of the possibility of upper-elevation snow.  

Finally, we have the plume for Salt Lake City.  There are two challenges for snow at the airport.  One is whether or not there's any precipitation.  The other is that when there is precipitation, the temperatures are marginal (note that it will be plenty cold here Sunday afternoon and Monday, but during that period it's likely to be dry).  It looks like 9 ensemble members call for virtually nothing, whereas the remaining 17 members give amounts ranging from trace to jus over half an inch.  

Not much to get excited about, but we haven't had much in the weather department for a long time.  


  1. You’re my go to when I’m wondering if I should consider touring tomorrow. Thank you!

  2. 11° in suburban Denver now with snow showers. Only 3" so far. Pretty chilly for October. I hope it helps to extinguish the massive wildfires.

  3. Revise "dust on crust" to "dust on ash".

  4. Wait, that isn't poetic at all. Maybe "flakes on bake", or the Deutch "schnee auf asche". Help!

  5. What is interesting to me is that this event, like two other somewhat recent ones (October 29-30, 2019 and September 8-9, 2020) is an unprecedented cold surge for so early in the season, as far back as records go. These events have all brought anomalous cold to fairly large areas of the western U.S. I am wondering if there is some common contributing factor, or simply coincidence? It might be interesting for someone to do a comparison of the evolution of these early season arctic cold surges, and any preceding or contributing factors.