Rain in Phoenix

Deborah in Phoenix reports:

At 10:12 PM on June 22 a monsoon storm hit Phoenix with high winds and buckets of rain. whoo hoo!

Interesting! And puzzling!

The dew point is now considerably higher than it was earlier today, and so there is definitely a flux of moisture into the area. But from where exactly? I remember seeing a paper several years ago that stressed the importance of a low-level nighttime southerly jet along the western slope of the Sierra Madre for bringing moisture into AZ. That jet must be active. Interestingly, the moisture is flowing faster than the storms: the storms are staying in mostly place, centered in the Nogales-Tucson area, almost like a mesoscale convective complex (MCC), and moving north rather slowly, but the moisture is passing THROUGH the storms, headed for points north. Strange. But if it works, so be it!