Dust Risk-Based Forecast | Maricopa County

Wednesday

Stagnation: Morning and evening stagnation

Wind: Mostly light winds

Thursday

Stagnation: Morning and evening stagnation

Wind: Mostly light winds

Friday

Stagnation: Morning and evening stagnation

Wind: Mostly light winds

Saturday

Stagnation: Morning and evening stagnation

Wind: Light winds

Sunday

Stagnation: Morning and evening stagnation

Wind: Light winds

Forecast Discussion:

Yesterday's air quality in Phoenix came in just about as expected, with ozone and PM10 (dust) remaining in the Good AQI, and PM2.5 (smoke) just reaching the Moderate AQI threshold. It is expected for ozone and PM10 to take quite some time to recover from that storm system this past weekend, especially with what we may expect over the next couple of days.

A cut-off low centered off the Northern California coast is expected to make its way towards Arizona today, and will reach the northern portion by early tomorrow morning. Though rainfall is not expected for the Phoenix metro area; good ventilation, cloud cover, and southwesterly winds of 5-15 mph will keep ozone and PM10 from elevating quickly. Just a steady increase in these levels are expected. PM2.5 is a different animal in forecasting as it is mainly human behavior, and is not affected as much by meteorological phenomena like the other two. Since we are moving further away from the weekend, PM2.5 is mainly driven by mobile sources such as transportation, and is not a elevated as levels on the weekends. This is when more stationary sources come into play like fireplaces, outdoor grills, and firepits. Due to lower values in PM2.5 this morning, levels are expected to be in the Good AQI category. Tomorrow levels will be around the Good/Moderate threshold.

For you air quality forecast, ozone and PM10 will increase steadily throughout the period, but are expected to remain in the Good AQI category. PM2.5 Will also increase throughout the week, but at a faster and more abrupt pace. Levels will reach the Moderate AQI by the back half of the week, and will be the main parameter to watch as we move into the weekend.

- B. Droppleman
ADEQ Meteorologist