Late June or early July is the traditional start time for the North American (or Southwest) Monsoon, during which moisture streams northward from Mexico into the southwestern U.S., bringing substantial showers to Arizona, New Mexico, Nevada, and sometimes Oregon, Idaho, and eastern Washington.
See the schematic below. Such monsoons are often associated with an area of high pressure over Colorado and northern New Mexico, which draws moist air from the Gulf of Mexico into the American Southwest.
In a few days, the monsoon will get revved up, and some of the wet action will reach portions of the Northwest.
Let me show you!
Here is the predicted precipitation total over the next 10 days. Some of the Mexican moisture pushes into Arizona and Nevada, and a small amount will extend into eastern Oregon.
The official NOAA Climate Prediction Center 6-10 day forecast is for wetter-than-normal conditions over the southwest U.S. The far southeastern portion of Oregon gets a wet taste of it.
As expected, this monsoon moisture will be driven by an upper-level high over the 4-corners area that will move moisture into the southwest from the southeast (500 hPa --about 18,000 ft map for each Sunday morning is shown below)
Here is the predicted precipitation for Tucson, Arizona. Very wet!
There will be some good thunderstorms in Arizona if you enjoy big boomers.
This is not a particularly hot pattern for the Northwest, and Seattle will stay moderate in temperature (see below).
I've become quite amused at how the use of the word 'Monsoon' has spread so rapidly in recent years. Two inches of rain over a week or more in AZ? What about two inches a day for 3 months of the year? That's the way it is with the 'original monsoon' in parts of South Asia, particularly up near the Himalaya.
ReplyDeleteThe term "monsoon" has been used to describe the summer weather pattern in the Southwest for nearly 80 years. It was first specifically applied to the region's seasonal summer storms in 1949 by geographer Ronald Ives, who referred to it as the "Sonoran Monsoon
DeleteThis is very interesting. Thanks for the information. I do accept that the term monsoon can be utilized to describe other seasonal wind patterns outside of Asia. But it is simply the most dramatic in S. Asia!
DeleteSteve S., monsoon does not refer to extreme rain, but an annual seasonal event that cause a lot of rain for a long period.
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ReplyDeleteSome years ago there was a video of folks in India waiting for and then experiencing the Monsoon. The crew doing the video moved north with the rain and chronicled the excitement and customs of the local communities. This was a cultural exposition and not a physical science explanation but there was some of the latter.
If the people of Arizona and northern Mexico respond similarly, I have not been exposed to such traditions. {In WA, east of the Cascades, we only get hot, dry, and winds. Oh well.}
"Monsoon" is from the obsolete Dutch "monssoen." first known use in 1584 for this summer circular rain event. And, south Asia has a lesser fall northeast monsoon. In the southern hemisphere is the summer event called their northeast monsoon?
ReplyDeleteDespite the sunshine and seemingly dry weather, it sure is muggy right now. It's 72 degrees out with a dewpoint of 58 right now.
ReplyDeleteFor not being a particularly warm day today, it has certainly felt warm. Amazing what a high dewpoint will do.
DeleteLake Powell could use a biblical style monsoon https://powell.uslakes.info/Level/
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