WeatherWatcher: Cold Blast, New Year's Day snow, December in review

Cold Blast: The forecast is calling for one of the coldest periods we've seen in a couple of years. With pretty good certainty it is expected to be sunny and cold through Friday afternoon. We are looking for high temperatures in the low-mid 30's and lows in the teens and low 20's. Wednesday will have a second strong outflow from Canada bringing temperatures down a notch once again.

Getting further out, next weekend has a storm moving in Friday night into Saturday that is expected to start as snow, but a warm up to rain is expected. Longer range is showing rain for a few days before another cold blast arrives around January 11th or 12th with a renewed chance of snow once again.

New Year's Day snow: We had snowfall New Year's Eve and New Year's Day, however the ground and air temperatures were still too marginal for most of it to stick. It wasn't until New Year's Day morning that temperatures got cold enough for snow to stick, however, most of the moisture had already started moving out by that point. The convergence zone band that was expected did develop, but it missed Shoreline and actually got Burien near Sea-Tac, dumping up to 6 inches of snow there. We dodged that heavier snow, but notice how easily that could have been us.

Total reported accumulations in Shoreline were up to 1 inch if you were further west such as Richmond Beach (Particularly North Richmond Beach neighborhood). Half inch of snow graupel was also reported in North City and at my weather station, with about a quarter inch of regular snow on top of it.

December in review: In short, December was colder than normal, with several minor snow events mixed in. The graph below shows our daily high and low temperatures compared to the station's average.

Daily average temperature graphed compared to the station's average gives you a better idea of how much colder December 2016 was. Notice the large dips around the 7-9th and 13-18th.

We had, in total, between all snow events, just over 4 inches of accumulated snowfall. Most snow on the ground at one time was 3 inches on December 9. Rainfall was short of normal but not by a huge amount. We are still well above normal for the season in rainfall. This graph shows the precipitation for the month, both in rainfall and snow accumulation. Note that any snow that falls and snow that accumulates is measured as rain when it melts in the rain gauge.

Here are the numbers for December 2016:

High temperature: 47.3°F (Friday December 2nd)

Low temperature: 21.7°F (Saturday December 17th)

Rainiest day: 0.69 inches (Friday December 23rd)

Total rainfall: 3.5 inches

Total snow accumulation: 4.1 inches

Average temperature: 36.1°F

Normal average temperature: 37.7°F (1.6°F below average)

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