Yesterday, peak 8 hour Ozone values just reached the Unhealthy for Sensitive Groups category. Very similar conditions are expected today and thus, the High Pollution Advisory for Ozone remains in effect for today. A big improvement in ozone is expected Friday with morning cloudiness (and possibly showers) being thicker and lasting longer which will reduce Ozone production and help keep levels in the upper Good category (close to the Moderate threshold). A gradual uptrend is anticipated Saturday through Monday with less storm activity and associated cloudiness.

Also like yesterday, Monsoon storm activity later today and tonight is expected to produce areas of gusty winds and pockets of blowing dust. But, winds are not expected to be quite strong enough to produce dense enough blowing dust to push the 24 hour average of PM10 out of the Moderate range. Likewise for PM2.5. Plus, a larger footprint of follow-on rainfall should help settle dust more quickly. Anticipate significant improvement in Particulates Friday with much less wind as well as more stabilized soils from rainfall. Modest outflow activity on the lower deserts is anticipated to continue in the Saturday through Monday time frame for continued daily averages in the Good range.

- A. Jamison
ADEQ Meteorologist