Tuesday, July 8, 2008

Monsoon Season Is Here

A huge part of the summer weather pattern here in the west is the annual monsoon.

The North American Monsoon, sometimes called the Mexican Monsoon, usually begins during the first week of July and lasts into the month of September. It can start as early as late June.

What exactly is a monsoon?

It is a seasonal shift in the wind pattern that usually lasts for a few months -- and in our case or the case of places like India -- that shift brings the wind pattern off a major body of water, and thus it transports moisture into the region.

For states like Colorado, Arizona, New Mexico and Utah -- it is a VERY critical part of the local climate, and provides very beneficial moisture to this arid part of the world.

Up until this year, the monsoon was declared active when the dewpoint temperature in Tucson, Arizona reached 54 degrees or higher for 3 consecutive days. The start date could range anywhere from June 25 to July 10.

Now, the National Weather Service is simply defining a monsoon season, which runs from July 1 through September 30. It is just easier when teaching public awareness to define an exact date range rather than waiting each year to see when it officially starts and ends.

Monsoon season brings a huge threat of flash floods.

If you like to watch the US satellite and radar, keep an eye on the 4 corners. Almost like clockwork, over the next several weeks, our states like up like a Christmas tree with radar returns shortly after the noon hour.

The daytime heating interacts with the moisture coming off the Pacific Ocean -- and we get numerous showers and thunderstorms.

Usually they have gusty winds, small hail and brief but very heavy rain. Tornadoes aren't usually a threat this time of year, but sometimes they can spin up for a few minutes.

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