As we move later into the monsoon season, increased moisture may increase monsoon activity. Now, developments off the coast of Mexico may further fuel Valley storms.
Arizona’s monsoon season ranges from mid-June to the end of September. While Monday evening’s storm came a bit past the traditionally recognized peak of early August, state climatologist Nancy Selover said a surge of stronger storms later into the season is no surprise.
“We have more moisture moving up from Mexico," Selover said. "And by the time we get to late August, we have the probability of being able to have very deep moisture in the Phoenix area. And when these storms come in, the don’t dissipate as soon as they come over South Mountain, they just continue on moving.”
Increased urban development and surface material, like concrete and pavement, releases heat slowly into the night. The resulting heat island effect often pushes less dense storms toward the periphery of the Valley. But a tropical depression off the coast of Mexico will likely send more moisture into Arizona, increasing air density. Couple that with daytime heat, Selover said it may may the rest of the week interesting.
“If the skies clear up a little, and we get some good daytime heating, we’ll start developing those same kind of thunderstorms that we saw the past few days,” said Selover.
About 2.5 inches has fallen in the Phoenix area this season. While we are on pace to end above the average 2.7 inches, we are still well short of the record 9.5 inches that fell during the 1984 monsoon season.
