publisher page - july 2008

The Arizona Monsoon

Summers in Arizona provide locals and visitors alike with one of nature’s most awesome spectacles of power – thunder and lightning storms The Sonoran Desert is defined by two rainy seasons per year, one of them being the Arizona Monsoon. As much as 70% of rainfall in the region can occur during the summer monsoon, although we typically receive one third of our annual rainfall during this time. Because of this, our desert is considered relatively “wet” when compared to others such as the Sahara.

The word “monsoon” comes from the Arabic “mausim” which means “season” or “wind shift.” In past years, the start date of the season began after three consecutive days of dew points above 55 degrees and typically lasted for a few months. This year, the National Weather Service decided to end the guesswork and set the monsoon season from June 15 through September 30.

Many desert plants are adapted to take advantage of this brief wet season. The monsoon plays a vital role in managing wildfire threat by providing moisture at higher elevations and feeding desert streams. Heavy monsoon rain can lead to excess winter plant growth, in turn a summer wildfire risk. A lack of monsoon rain can hamper summer seeding, reducing excess winter plant growth but worsening drought.

Flash flooding is a serious danger during the monsoon season. Dry washes can become raging rivers in an instant, even when no storms are visible as a storm can cause a flash flood tens of miles away (never camp in a dry wash in the desert). Lightning strikes are also a significant danger. Because it is dangerous to be caught in the open when these storms suddenly appear, many golf courses in Arizona have thunderstorm warning systems.

The strength of a monsoon can vary greatly from day to day. Some are nothing more than a gentle dust storm, while others produce tremendous thunder. A typical storm starts with high winds and a towering wall of dust that moves across the Valley. It is usually accompanied by heavy thunder and lightning and downpours.

However, it is not all doom and gloom. In addition to providing the desert with much needed water, these storms produce some of the most incredible thunder and lightning storms you’ll ever see.

A bit of common sense will get you through a monsoon. Don’t cross a wash or road with running water. Take the usual steps to protect yourself from lightning. Slow down when driving. And by all means, enjoy nature’s light show in the desert.

Thomas J. Ruberto
Owner / Publisher

Monsoon information courtesy of the National Weather Service and Wikipedia.