Anticipate isolated thunderstorm activity over southeast AZ today before coverage increases significantly Saturday afternoon and evening. There will be day to day fluctuations in storm coverage through Tuesday but otherwise a familiar Monsoon pattern will be in place. With the upswing in Monsoon storms, anticipate more cloudiness and a downtrend in high temperatures. Until then however, an Extreme Heat Warning (issued by the National Weather Service) is in effect today and Saturday.

Peak 8 hour average Ozone levels today are anticipated to reach the Moderate category and thus the High Pollution Advisory has been cancelled. Anticipate a little bit of improvement Saturday to the low Moderate range with additional improvement Sunday to the upper Good range and remaining there through Tuesday.

Daily average PM10 is expected to remain in the Good range through Tuesday. Of note, as storm activity increases, there will be more potential for strong winds and in turn short lived episodes of blowing dust. But, those spikes in the hourly readings, if any, are not expected to be high enough to raise the daily average out of the Good range.

Daily average PM2.5 is anticipated to just reach the Moderate threshold today before improving over the weekend to the Good range. Daily readings are expected to trend up a bit during the early part of the next workweek with a typical increase in commercial and transportation activity but remain in the Good range through Tuesday.

- A. Jamison
ADEQ Meteorologist