summer rain

Monsoon forecast 2012

The University of Arizona is predicting our summer monsoon rains “to be more vigorous than average, with a strong beginning and end.”  See full story here.   The Old Farmer’s Almanac is predicting “near normal rainfall.”  See here.

Arizona’s monsoon in July, August, and September occurs because a high-pressure area perches over the Four-Corners area and draws moist air from the Gulf of Mexico and the Gulf of California.  The mountains and summer heat cause updrafts that condense the moisture-laden air to produce rain from thunderstorms.

To better understand thunderstorms, see my post Anatomy of a Thunderstorm.