Weather Service defines 'Arizona Monsoon Season' - East Valley Tribune: News

Weather Service defines 'Arizona Monsoon Season'

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Posted: Monday, March 10, 2008 8:01 pm | Updated: 9:49 pm, Fri Oct 7, 2011.

When it comes to safety during the monsoon, Arizonans seem to be missing the point - because they're too concerned with the dew point.

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The National Weather Service announced Monday it is scrapping the strict meteorological definition of the monsoon - the yearly weather phenomenon bringing thunderstorms to the Valley.

Instead, June 15 through Sept. 30 will be designated statewide as "Arizona Monsoon Season."

Until this year, the monsoon was said to begin when there were three consecutive days with a dew point, which relates to moisture in the air, of at least 55 degrees. Yet damaging thunderstorms can erupt weeks before that mark is reached, and some residents aren't prepared.

"It's pretty evident, to me, people don't get it," said Tony Haffer, the Weather Service's meteorologist in charge of the Phoenix office.

Under the new designation of a distinct season, Haffer hopes the focus will be on the potential for lightning strikes, dust storms, flash floods and punishing winds.

"The real issue is raising awareness of the violence of this weather," Haffer said.

The change is sure to create controversy. Last year, after news broke that Haffer was thinking of creating "summer thunderstorm season," the Tribune's online commenters came out passionately against dropping the monsoon name.

Haffer listened.

"The article suggesting we eliminate the word 'monsoon' was tantamount to suggesting we open our borders and invite all the terrorists in," Haffer joked. "It was the worst possible thing I could've said."

Haffer knows he is inviting criticism from pedants pointing out that "monsoon" comes from the Arabic word for "season," creating a redundancy on par with Table Mesa, the geographic feature and road in far northern Maricopa County.

Also, the monsoon is most accurately described as the change in wind direction which carries moisture into the state. Now, Haffer could be accused of embracing the common error of referring to an individual thunderstorm as a monsoon.

This time, Haffer won't listen.

"We're going to get some heat on this, and that's just fine," Haffer said.

The old 55-for-3 description was good, Haffer said, when it was developed in Phoenix about 50 years ago. It was a simple yet accurate measure of when moisture-laden air had surged into Arizona from the gulfs of California and Mexico.

But as years passed, this benchmark began to develop cracks. For example, experts realized Tucson entered monsoon conditions at 54 degrees dew point. Technology improved to the point that meteorologists could determine variations in humidity across large regions.

The old method also lacked finality. Haffer said there was no hard and fast way to determine when the monsoon was over. Instead, experts created an estimated end date by reading wind patterns, dew points, rainless days and so on.

Now, the monsoon is over when it's over.

Haffer said the new monsoon season's start and end is a "good window, and one that's probably going to get 99 percent of our most violent weather in the course of the summertime."

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