A classic wave of monsoonal thunderstorm/rain activity swept through central Arizona yesterday, this time from the northeast. A line of gusty winds led the way, resulting in dust in western Pinal County. All PM10 monitors in western Pinal County saw a substantial bump in PM10. However, rain quickly followed, knocking down dust.

Looking ahead, we will have the potential for a repeat wave out of the north or northeast this evening/night. A low-pressure disturbance from the east will provide the needed atmospheric assistance for this. Details are hard difficult to pin down, as always, but brief blowing dust may be possible again.

After today, the monsoon does finally look to calm down a bit, at least for the Valley. Instead, we'll have to contend with the heat. Temperatures will approach 110°F, and the National Weather Service has issued an Extreme Heat Watch for Thursday-Monday.

During this time, we'll have to watch ozone, as the drier, sunnier, and calmer conditions will favor local ozone formation and build-up.

PM10 and PM2.5 (smoke) will return to being mostly locally driven, though we can't rule out outflow winds from distant thunderstorms in the evening/night. However, the recent rain should help to limit PM10 levels.

Check back again tomorrow morning for the next update!

- M. Graves
ADEQ Meteorologist