This morning, if you looked at satellite data and national weather maps based on weather balloon data, you would see a large low-pressure circulation/wave from the Pacific Ocean advancing into the continental U.S. This system will be the main driver for Arizona's weather the next couple days.

Already this morning, thick cloud cover is spreading over Arizona from the southwest, ahead of the circulation/wave. Moisture has also increased significantly around the state. Once rising motion associated with the circulation reaches southeastern Arizona, rain chances will begin.

The bulk of rain looks to be later tonight into Thursday. Areas in/around Tucson could see upwards of a half inch of rainfall in total, with higher terrain areas seeing more. The more rain that southeastern Arizona can get today, the better, as that will reduce the dust risk tomorrow, when the stronger winds arrive ahead of a front. However, we can't rule out pockets of dust this afternoon before any rain begins.

Beyond Thursday, conditions look to dry up and clear out. Temperatures will also be cooling down, with highs topping out in the 70s. Assuming enough rain falls, local PM10 (dust) levels will be low. However, PM2.5 (smoke) will have the potential to be somewhat elevated during overnight periods.

Check back again tomorrow morning for the latest!

- M. Graves
ADEQ Meteorologist