Monsoons, more than rain clouds, dust storms

  • Published
  • By Senior Airman C.J. Hatch
  • 56th Fighter Wing Public Affairs
LUKE AIR FORCE BASE, Ariz. --  Starting June 15, things in Arizona can get a little bit electric, the sky will darken, the wind will pick up and liquid will fall from the sky. The Arizona Monsoon season, brings with it those little black rain clouds that can quickly escalate into full blown thunderstorms.

According to the National Weather Service, "the word monsoon is derived from the Arabic word mausim which means season. Ancient traders sailing in the Indian Ocean and adjoining Arabian Sea used it to describe a system of alternating winds which blew persistently from the northeast during the winter and from the southwest during the summer. Thus, the term monsoon actually refers solely to a seasonal wind shift and not to precipitation."

For many years there was a debate over if the Southwest actually had a monsoon. The Southwest Arizona Monsoon Project from 1990 to 1993 determined that Arizona truly did have one and is characterized by large-scale winds and rainfall shifts.

The monsoon season in Arizona has three phases that go from mid-June to late September: the ramp up, peak and decay.

The ramp up starts mid-June as tropical moisture begins to flow into the Sierra Madres in Mexico. During late June and early July the moisture causing many of the storms begins to move north through Mexico to the Arizona border.

"Most of the rain from these mainly mountain thunderstorms evaporates before reaching the ground," said the NWS. "The storms will produce strong, gusty and highly variable wind and dry lightning. By this time, the mountain forests have not received precipitation since April, so both live and dead vegetation is at its driest. Thus the risk of wildfires is at its highest as well."

As the moisture moves north, the monsoon season reaches its peak starting around mid-July.

"This is monsoon prime time in southeast Arizona," the NWS said.
Even though the peak monsoon brings rain to the valley there are safety concerns of which to be aware.

"There are seven safety factors to look at," according to the NWS in Tucson. "Lightning, straight-line winds, dust storms, flash floods, tornadoes, hail and excessive heat."

These conditions can be present during all phases of the monsoon season.

"The monsoon is the busiest time of year for us here at the Luke weather shop," said Staff Sgt. Tanya Davis, 56th Operations Support Squadron weather forecaster. "Dust storms limiting visibility, thunderstorms and strong cross-winds shutting down the runway, and severe winds causing damage on base are always concerns during these storms. It can be very challenging, but we always try to stay on top of the situation and prepare agencies for what's to come to keep personnel and other assets protected."

The last phase of the monsoon, the decay, begins late August and can last until late September. During the decay, things begin to calm and thunderstorms weaken.

The lack of low-level moisture and a more stable atmosphere causes thunderstorm activity to diminish and the monsoon to fade, according to the NWS.

The decay phase doesn't mean the dangers of the monsoons are over. In this phase, the weather can still turn active.

For more information on the Monsoon, visit the Tucson National Weather Service web page on Monsoons at http://www.wrh.noaa.gov/twc/monsoon/monsoon_info.php.