Ask a Climatologist: How the jet stream affects Alaska

Banded cirrus clouds run perpendicular to the jet stream—a telltale feature photographed by an astronaut aboard Space Shuttle Discovery. (Photo courtesy of NASA’s Goddard Space Flight Center)

The jet stream circles the globe from west to east affecting weather, climate and even the length of many airplane flights.

This week on Ask a Climatologist we’re answering a question from a listener who asked how the jet stream affects weather in Alaska.

Climatologist Brian Brettschneider says the jet stream is basically a ribbon of air circling the globe at high speed.

Interview Transcript:

Brian: It’s generally the boundary between cold, polar air and much warmer mid-latitude or subtropical air. It’s always present, all year round, but it varies in intensity quite a bit and when it’s not quite as cold, in the summer months and fall months it’s in the vicinity of Alaska. In the heart of the winter, usually it’s farther south so it doesn’t really affect us that much. But it’s always there, so it’s something that’s of great interest to the weather and the climate community, to the aviation community. So a lot of people are focused on where the jet stream is, how it’s moving and what it’s going to do over the next number of days.

Annie: But in Alaska, it doesn’t affect us too much?

Brian: The jet stream does affect us here in Alaska. Particularly in the fall and the spring months, we are right at the boundary of where the cold polar air is and the much warmer air farther to the south. The jet stream moves like a ribbon, so at times it goes up and other times it goes down and it has to stay in equilibrium. Where it comes down, you actually spin up low pressure areas and those then form precipitation and have wind. We do have these large fall storms and sometimes in spring as well, those are very frequently associated with these dips in the polar jet stream as they’re situated near Alaska.

Annie: And how is climate change affecting the jet stream?

Brian: In the last few years, there’s been a fair bit of research that’s looked into this issue of what does a warming world do, what will it do to the jet stream. The strength of the jet stream is the temperature difference between the high latitude, arctic polar latitudes, and the equatorial or tropical latitudes.

In a warming world, high latitudes warm faster and that difference in temperatures is reduced which then reduces the strength of the jet stream. The jet stream in a weaker state is more susceptible to these wild gyrations. When you have this jet stream that’s more susceptible to moving around, in the Lower 48 you can get paradoxically more arctic outbreaks. But then you can also get more dramatic warm ups in the winter. So, more variability and more storms are possible.

It’s something that’s an emerging area. It makes sense from a physics point of view and now researchers are trying to put that puzzle together and confirm what they think the theory indicates.

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