Dust Risk-Based Forecast | Maricopa County

Tuesday

Stagnation: Morning and evening stagnation

Wind: West-southwest winds of 5-10 mph

Wednesday

Stagnation: Morning and evening stagnation

Wind: South-southwest winds of 5-10 mph

Thursday

Stagnation: Morning and evening stagnation

Wind: Light and variable winds. Outflows possible in afternoon

Friday

Stagnation: Morning and evening stagnation

Wind: Light north-northeast winds

Saturday

Stagnation: Morning and evening stagnation

Wind: East winds of 5-10 mph

Forecast Discussion:

Decent cloud cover outside this morning with some very light and sparse rainfall as well. Sky Harbor has recorded a couple of traces early this morning, and if we see measurable rainfall (an amount equal to or above 0.01 inches), we will be tied with the record number of measurable rain days during the monsoon season! 2021 is currently ranked 2nd with 23 days of rain equal to or greater than 0.01 inches, and the number one spot dates back to 1896 with 24 days. With the continued chance of rain today and later this week, we could tie or break this record!

The disturbance that has been assisting with the showers across the state this weekend is looking to move out of the region by tomorrow. As this weather system makes its way eastward, there are still chances for isolated rainfall today throughout central Arizona. Tomorrow the valley will receive a short break from these "rainy" days but we are expecting another trough to sweep through Arizona Wednesday afternoon through Thursday. We could see additional thunderstorms develop during these couple of days later this week. We'll keep an eye on the timing and moisture content of this disturbance as we progress through the week.

Once this second system passes through, a warming trend should begin for the valley. Recent/upcoming rainfall and cloud cover has kept our temperatures in the 80s, but by the end of the week/weekend, we will expect a few more 90 degree days.

As for air quality, ozone is going to be a tricky pollutant to forecast for this week. Cloud cover and dominating low-pressure help reduce ozone values, but depending on how long the cloud cover sticks around during the afternoon, ozone can quickly begin to rise (ozone needs sunlight to form). As a result, we are forecasting Good Air Quality Index (AQI) for ozone today, and Thursday but Moderate AQI the rest of the time. PM10 (dust) and PM2.5 (smoke) should have no problem remaining in the Good AQI range this forecast period thanks to recent and upcoming precipitation.

Have a great day!

- P. Swenson
ADEQ Meteorologist