The Arizona monsoon season produces up to a third of the region's annual rainfall but it is tough for forecasters to predict.
Some longtime residents of Arizona said the monsoon season is not as severe as it once was, The Arizona Republic reported. But possible explanations for the tamer weather range from urban sprawl to global warming.
Christopher Castro, a climate scientist at the University of Arizona who has worked extensively on monsoon study projects, has suggested the phenomena of El Nino and La Nina might cause monsoons. Scientists have looked to the equilateral Pacific Ocean for possible answers to the weaker monsoons.
Despite technological advances that allow meteorologists to predict trends on a planet-wide scale, monsoons have always had a random, unpredictable nature, the Republic said.
Copyright 2007 by United Press International
Explore further: Huge tract of Australia in 'biggest ever drought'