Dust Risk-Based Forecast | Maricopa County

Saturday

Stagnation: Morning and evening stagnation

Wind: Light west-southwest winds of 5-15 mph

Sunday

Stagnation: Morning and evening stagnation

Wind: Light west-southwest winds of 5-15 mph

Monday

Stagnation: Morning and evening stagnation

Wind: West-southwest winds of 10-15 mph

Tuesday

Stagnation: Morning and evening stagnation

Wind: West-southwest winds of 10-15 mph

Wednesday

Stagnation: Morning and evening stagnation

Wind: West-southwest winds of 10-15 mph

Forecast Discussion:

Monsoon activity is undoubtedly in full swing across Northern Mexico as several large thunderstorm complexes have developed over the past week. Another formed yesterday afternoon/evening, and as it collapsed, it sent debris clouds over the state, including the Phoenix Valley overnight into this morning. These clouds have also resulted in a warm morning, with the low temperature at Sky Harbor coming in at 91 degrees, which ties the record for this day of the warmest low temperature.

So what's going on? A large area of high pressure is currently sitting just east of the Arizona/New Mexico border and extends from the Southern California coastline back through Arkansas and Lousiana. Today through Sunday, the ridge will shift ever so slightly west over the Arizona/NewMexico border, and strengthen as it does so.

This strong area of high pressure will result in a few things: (1) scorching temperatures, with afternoon highs in Phoenix forecast to be in the 112 to 118-degree range today through Monday, with an excessive heat warning in place. (2) easterly/southeasterly flow around the high will import moisture into the eastern and southeast portions of the state, which will result in a chance of thunderstorms across the higher terrain of northern, eastern, and southeastern Arizona. (3) thunderstorm activity and the high pressure position will allow debris clouds to move over the Valley the next couple of days. If these clouds stick around through the late morning and early afternoon, it could help to keep temperatures slightly lower than currently forecast.

As for rain in the Valley, it is looking like it will stay rather dry. With that said, would not be surprised to see a weak outflow or two move through the Valley from the northeast or southeast where thunderstorms have the chance to form and collapse as they move off the mountains. Right now, not expecting widespread blowing dust as outflow looks to be fairly weak as they move into the Valley but will be watching trends closely.

Late Monday into the middle of next week, a trough will move into the Pacific Northwest, which will help to push the high further east, and potentially bring some dryer air into the region.

As for air quality, ozone concentrations are still forecast to be on the rise, but expecting them to stay below High Pollution Advisory criteria. The main reasoning is continued breezy winds each afternoon, the possibility of debris cloud cover, and weak outflows moving through allowing ozone to continue moving and not have enough time to influence the 8-hour average.

Have a great weekend, and another reminder to stay hydrated, take plenty of breaks if working outdoors, and NEVER leave your kids or pets in the car, not even for a minute!

- M. Pace
ADEQ Meteorologist