Monsoon season for the four corners, but the dry season is here for us


PORTLAND, Ore. (KOIN) – Are you familiar with the North American Monsoon season? This is a summer event that impacts many states to the south of Oregon.

It’s a wind pattern that helps provide the moisture for summer storms and flood events for the four corners and neighboring states. This event offers more rain to areas like Arizona in the summer than places like Oregon and Washington.

The monsoon season can bring anywhere from a few inches of rain to upwards of 7 or 9 inches of rain for locations like Phoenix over the span of a few months, which is some hefty rain for the summer. The monsoon really starts to crank around mid-July for those states; meanwhile, we are entering our driest months locally.

Above is a chart that helps layout the weather pattern as we start to push through the summer. High pressure sets up east of the four corners area allowing for the wind to travel from the south upwards to locations like Utah and Colorado. This direction of the wind helps usher that moisture in from the gulf and that low at the south end of California will usher in moisture from the eastern Pacific.

However, at this time, the jet around the Pacific Northwest is driving moisture to the north of areas like Oregon and Washington. It also is split from the motion of the monsoon high coming in from the south. It virtually puts us in a zone that is benign, outside of the influence of our local geography. The satellite below paints a dry and clear environment for the PNW, while storms fire up around the four corners.

Let’s digest some of the dry stats for our July. We have a pitiful .05″ of measurable rain as of July 15. We started the month with a splash and then had another splash on July 7. We are now 0.31″ below our normal for the month, which isn’t very much rain in the first place. We know this and that is why the drought conditions leading up to the summer is very important.

The drought monitor for the United States is bleak for some locations, including Oregon. Those locations that will pick up moisture from the monsoon season may see some improvements. However, our conditions in the PNW may exacerbate when it’s all said and done this summer. There are currently no signs of measurable rain in the forecast for Portland.

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