Fri. Dec 13th, 2019

Meandering jet stream delivers warmth to the Arctic, unusual storm to South Oregon, strong, cold easterlies to South Island.

A very strong low pressure ‘bombed’ off of the coast of Oregon and Northern California last night. This explains the very strong winds this morning.

Check out the animation in this tweet.

There have been power outages and impacts on BC Ferries.

You can see the low on the UWash maps as well. It has moved inland into southern Oregon this morning. Winds flow along the isobar (pressure) lines you see below. The tighter the lines, the lower the low, and the stronger the winds.

A 986hpa low is extremely low and it is unusual to see something like that so far south. Usually our area — Washington, and the BC coast — are about as far south as these storms get. They are most common on the North BC and Alaska Coasts.

The culprit? An extremely wonky jetstream.

The culprit of that wonky jet stream? This is an area of very active research and we’re getting into a very complex process. A lot of research points to a warmer Arctic lessening the temperature difference between north and mid-latitude areas is making the jet stream less “latitudinal”…ie: it doesn’t flow west to east. as much. It’s meandering like a lazy river.

Arctic sea ice remains at or near record lows for this time of year.

The most prominent area with lack of sea ice for this time of year is the Bering Sea and Chukchi Sea, which lie on the south and north side of the Bering Strait respectively, separating Alaska and Russia, see the zoomed in area below.

The orange line is essentially where the ice ‘should’ be at this time of year.

This is a positive feedback loop. If you look again at the image further up with all the rainbow of colours. The jet stream (brighter colours) is flowing northward, toward Alaska, the Aleutians, and the Bering Sea.

As we know when we get our “Pineapple Express” or “Atmospheric Rivers”, the jet stream brings warm winds with it from the tropical ocean. That’s going to make it harder for ice to return, which will make the air warmer than normal, which will cause this kind of meandering pattern…. and so on.

Sometimes climate change is difficult to see in front of us. Today is not one of those days.

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