WeatherWatcher: The cold is here, coldest air since December 21, 1990

 

Band of clouds in the weak convergence band on the leading edge of the modified arctic front.
January 11, 2024, photo by Gordon Snyder

Thursday afternoon, as arctic air surged out of Canada, a leading convergence band of clouds and snow showers in a northwest to southeast line developed near Marysville and slowly moved south. 

Initially passing through Everett and south Snohomish County, it then moved into Shoreline, Lake Forest Park, and other east side communities such as Kenmore and Kirkland. Some of the showers made it past downtown Seattle and Bellevue before drying out.

The arctic air is here now, and it has turned out to be the coldest arctic air our region has seen since December 21, 1990, where we had a daytime high temperature of 14°F. 

Our high temperature on Friday was set at midnight at 25°F. Later Friday morning about an hour after sunrise our low temperature was set at 13°F, only to rise in the daytime hours to 18°F before the sunset. 

Another interesting thing that happened Friday is sublimation. The small amount of snow that accumulated in the area started to evaporate. This arctic air mass is very dry, with dew points in the single digits. When you have very dry air, snow and ice can transition directly from a solid state into water vapor. 

I observed an icicle do this in my back yard. Instead of melting, it evaporated slowly throughout the day with no visible liquid water. The evaporation started during the overnight hours Friday morning.

What's ahead:

Saturday could be an even colder day yet; we are looking at low temperatures into the low teens or possibly single digits (if you're away from the Puget Sound or Lake Washington.) Daytime high temperatures may once again not make it past the 20°F mark. 

Some clouds are possible on Saturday and maybe even a stray flurry as a storm passes us to the south. Portland, Oregon is expected to get the bulk of that snowstorm. 

That said, there still has been a lot of change in the forecast so uncertainty remains. There is an extremely slight chance that we might see a snowfall Saturday or Saturday night.

Sunday is expected to be sunny and cold, but temperatures are expected to come up a little bit and bring us into the low to mid 20's for a high temperature. Lows will be dipping down into the upper teens or low 20's Sunday night.

Monday and Tuesday are expected be mostly clear and sunny as well with each day getting a little bit warmer. 

Our next Pacific storm approaches Tuesday afternoon and evening, and there is a lot of disagreement how that will start out. 

I will do another update on Monday, but at this time forecasts are leaning towards a snowy start with an eventual transition to above freezing temperatures and rain by Wednesday afternoon or Thursday.

For current weather conditions in Shoreline visit www.shorelineweather.com