Wild December Weather, and a Less Active Start to the New Year

December was an incredibly active month, with punishing winter storms affecting the entire West. There was an amazing arctic outbreak in the Pacific Northwest, bringing the coldest temperatures in many years. Daily temperature records fell in the lowlands of Western Oregon and Washington, along with snow falling at sea-level. The North interior of Washington experienced blizzard-like conditions with over a foot of snow falling in the Bellingham and Port Angeles areas. This storm pushed south into California, and later brought a blast of winter weather to the interior West. In fact, it was record breaking snowfall in parts of the Sierra Mountains. Check this out from the Berkley Lab at Donner Pass, which ended up with 202" by the time it was all done. 

This wasn't just a great snow month for the Sierra Mountains, it was terrific throughout the West. Check out this snow water equivalent map as of Jan 3, 2022. Many interior mountains were way below average after a very disappointing November. But look now, most mountain sites are actually above average! Light green/Light blue is near 100% and dark blue is near 200% of average! 

Want to know a little more about Utah? Well, I have some good news to share on that front as well. The Salt Lake Airport had a very late first measurable snow, but not the latest on record which occurred on Christmas day, twice. There was no snow measured for the water year at the airport (starts October 1st) until 1.4" fell on December 9th. This was the start of a major pattern change, with a parade of storms battering Utah through the remainder of the month. Temperatures averaged out to slightly warmer than normal due to the very mild first week of the month. The rest of the West was generally colder than average, and greatly contrasts with the above average temperatures across most the Eastern part of the country. Here's the December average temperature anomaly:

It's hard to believe, but after measly snowfall in Utah last November, we are actually above average at most spots for the water year, ending Jan 2nd. Don't believe me? Here's the Alta accumulation graph from October 1st to Jan 2nd. Slightly above average snowfall (green). The average is the brown line. Better yet, liquid equivalent is several inches above average.  

The valleys have also done great with snow. December snowfall at the Salt Lake Airport reached 21.5" by the end of the month, way above the average of 12.1". Snowfall and liquid equivalent is now above average for the entire water year for Salt Lake City! Not easy to accomplish.   

So, what should be expected as we head into January with substantial progress under the belt? Right now, trends look OK, but not great. Here's the expected rainfall over the next 7 days. A couple of modest storms will bring mostly valley rain to northern Utah and maybe a couple inches liquid to the northern mountains. This would translate to perhaps 2-3 feet of snow at the ski areas over the next 7 days, not bad! However, the pattern evolves into something less than ideal for the mid part of the month. Take a look at the official Climate Prediction Center Outlook for days 8-14. Mild temperatures and below average precipitation. Not so good. 

What about the rest of January? That's a tough call at this point. I would NOT expect January to end as a block buster month for rain or snow. Long range models do show some indication that a long wave trough (a region where storms tend to be active) may develop again over the West toward the end of the month. This doesn't tell us much about certain details, such as potential valley snow. It does indicate more active weather is possible and could bring more snow to the Utah mountains. The signal is not strong, but it's there, so let's hold out hope! We need several good months of active weather to get our snowpack up and get those reservoirs in better shape for this summer! Happy New Years!