All Weather News

How the Jet Stream Influences Heat Waves!

6 Jul 2015, 11:37 am

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The Pacific Northwest has seen more than its fair share of heat this past month.  Record high temperatures have been the norm in cities such as Seattle and Portland, Oregon, over the past month.  The unusually warm and dry June has also led to many fires such as the Sleepy Hollow fire in Wenatchee, Washington, and the 231 fire outside of Springdale, Washington.

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Much has also been said about the jet stream and how its unusual and persistent position in the atmosphere has allowed such extreme conditions to persist in the Pacific Northwest. But what exactly is the jet stream? And how does it cause the unusual heat in the Northwest for much of the past month?

First, the jet stream is a fast flowing, relatively narrow air current found in the atmosphere around 10 kilometers above the surface of the Earth, which forms at the boundaries of adjacent air masses with significant differences in temperature. Sure enough, the jet stream has formed right on the boundary between warm and cooler air.  Some meteorologists also say that the jet stream “allows” warmer air to move northward, while others would state something like the definition above. So which is true?

It turns out that – in some cases – both can be true.  The jet stream is as much the victim of the air masses on either side as well as affecting where it is cooler and warmer.  Certain large-scale phenomena like El Nino affect jet stream patterns, and jet stream itself can effect other large-scale patterns such as redirecting tropical cyclones. 

So is the heat “forcing” the jet stream further north, or is the jet stream “allowing” heat to travel northward? In reality it’s a bit of both. Forecasting the jet stream is like any other long-term forecast problem. Meteorologists are working all the time to develop better models to predict the behavior of the jet stream. Eventually we’ll solve that problem, and in turn be able to predict when and where the next crippling heat wave may strike.

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