Over the next several days, the monsoon will return to an active phase for southeastern Arizona. This means daily chances for thunderstorms in/around Tucson. Sunday afternoon/evening in particular looks to be a noteworthy time of greater thunderstorm coverage over the area. And if Sunday ends up being very active, Monday could be more of a "down" day for thunderstorm activity, as the atmosphere as to reload, as it were. For any thunderstorm that develops, clouds, gusty winds, and/or heavy rain can be expected, along with hazards such as lightning and blowing dust (prior to any rain).

Consistent with past air quality forecasts, ozone will continue to be the main pollutant to watch throughout this period. When light winds and sunny skies are present, local ozone formation and build-up can occur. However, how high ozone is able to reach will depend on timing of thunderstorms, or at least the timing of their winds and clouds arriving in Tucson. Ozone is forecast in the Moderate AQI category each day.

In regards to PM₁₀ (dust), briefly elevated PM₁₀ will be possible initially when thunderstorm gusts occur. But any rain will help to decrease airborne dust. In general, both PM₁₀ and PM_2.5 (smoke) are forecast in the Good AQI category each day.

Check back on Monday for the latest!

- M. Graves
ADEQ Meteorologist