A monsoon in Arizona? Yes, indeed. The term monsoon was originally defined for the Indian subcontinent. It is actually a wind shift which brings precipitation. The Arizona Monsoon (some call it the summer thunderstorm season) is part of the larger Mexican Monsoon which occurs throughout the southwest area of the continent from Mexico to as far north as Wyoming.
Two things happen to bring on our monsoon. Heat builds in this area in April, May and June (with temps well over 100 F), and an upper level high pressure system (Bermuda High) moves north from winter to summer. These two events cause the wind to shift from a west or northwest direction to a south or southwest direction bringing tropical moisture from the Gulf of Mexico and the Gulf of California and with it humidity, clouds and rain.
|Arizona Dust Storm July 5, 2011|