For us in Teton Valley, a strong North American monsoon brings us daily afternoon thunderstorms almost like clockwork.

It’s baaaack! You’ll see it in forecasts and discussions from the National Weather Service and in television and radio forecasts. The M word has returned: MONSOON!

When you hear that word used around here, you don’t have to start building Noah’s Ark or anything. If you are familiar with the heavy monsoon rains that are currently threatening India’s wildlife, or maybe you are a veteran --thank you! — who remembers the monsoons of SE Asia, the word has a whole different and much milder meaning here.

Around here, when people use the word monsoon, they mean a much smaller event more correctly called the North American monsoon, or sometimes the Mexican monsoon.

In parts of the world where true monsoons occur regularly, monsoon means a complete 180 change in the direction of the wind which usually brings heavy rain. While these rains can be devastating due to the flooding they bring, without them there would be devastating famine without the crops that depend on monsoon rains to grow.

The North American monsoon involves a change in wind direction and increased precipitation too, but neither is as dramatic nor long lasting as the Asian version. This has a lot to do with geography, the size of the plateau over which the wind blows and the arrangement of land and sea areas.

Were it not for the North American monsoon, parts of northwest Mexico would be without 50 percent of their annual water. There and in the southwest United States, this annual replenishment of the water supply is vital.

For us in Teton Valley, a strong North American monsoon brings us daily afternoon thunderstorms almost like clockwork. Occurring late in the summer, this is a mixed blessing. After a long hot, dry spell, the rain is welcome but the lightning and wind add to wildfire danger. By mid-September, the monsoonal weather pattern breaks down and fall sets in.

You will undoubtedly see the word monsoon used in weather forecasts as summer unfolds, even on the Teton Valley Weather Facebook page. But when you see it, think afternoon thunderstorms, not those hard flooding rains of the monsoons in India and Southeast Asia.


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