Science behind a weather heat dome

The heat dome over the southwest

MINNEAPOLIS - By now, you have probably heard about the extreme heat in the southwest. In Phoenix, temperatures have been 100 degrees or warmer 23 of the 26 days we have had so far this month.

What that much heat, a heat dome has formed over the southwest United States, and this can affect our weather.

A heat dome forms under a zone of high pressure. Think of it like a plate cover that's designed to keep food warm. The heat dome does the same thing -- it traps the heat under a zone of sinking air, which keeps the skies clear and the temperatures hot.

When this happens in the atmosphere, the jet stream goes around it, and in this case, it moves right on top of us, increasing the chances we get passing areas of low pressure, or thunderstorms with heavy rain.

Here in our area, we had a chilly weekend and it continued this morning when we had temperatures drop down to 39 degrees in the North Metro.

So how does this weather pattern change? It all depends on what storms develop over the eastern Pacific Ocean.

This hurricane, along with other incoming oceanic storms, will move the jet stream to more of a normal position, warming us back up and giving us chances for more thunderstorms this week.

© 2017 KARE-TV


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