FORECAST SUMMARY: Monday, July 10th, 2023, through Friday, July 14th, 2023
OZONE: 8-hour average Ozone concentrations Monday will range between Good and Moderate north and Moderate to USG south; Good to Moderate readings are expected the rest of the forecast period.
PM-2.5: 24-hour average Fine Particulate levels will range between Good to Moderate
FORECAST DISCUSSION:
A boundary sinking into the region brings clouds and precipitation chances Monday across the Upper Peninsula while dry conditions can be expected further south in the Lower Peninsula. Ample sunshine combined with southerly winds and warm surface and upper-level temperatures sets the stage for ozone development in the most prone locations; the western lakeshore and the southeastern portions of the state. We had an Air Quality Action Day in place on Monday in those areas to cover this threat. As the boundary treks southeast through the state, clouds and precipitation move with it late Monday into the day Tuesday. This boundary looks to stall just south of the state Wednesday with cooler temperatures in its wake.
As mentioned above, we had an Air Quality Action Day in place on Monday where 8-hour ozone concentrations into the USG range were possible. Across the rest of the state, levels will average Good to Moderate. Clouds increase from northwest to southeast Tuesday. This increase in cloud cover should help keep ozone from significantly developing, but Moderate readings are still possible, especially in the south/southeast. If clouds hold off Tuesday in the southeast where mostly sunny conditions linger there is a chance a monitor may increase back into the USG range, but that threat isn’t high enough at this time to warrant an action day. For the rest of the period, unsettled conditions are expected as the Wednesday boundary stalls south of the state. Some cloud cover and on and off storm chances should keep ozone from increasing higher than Moderate Thursday and Friday. If this changes, the forecast will be updated.
As for fine particulate, smoke models were evaluated, and a plume is overhead Monday with another plume associated with the approaching frontal boundary expected to move in as the front passes. The plumes, however, are not expected to significantly increase ground level fine particulate concentrations. As a conservative measure, we are forecasting Moderate levels both Monday and Tuesday. Cooler northerly winds should bring levels closer to Good, but the boundary south of the region may allow for Moderate levels in the south Thursday and Friday.
EXTENDED FORECAST:
Forecast models show cooler temperatures with on and off precipitation chances through the coming weekend. If this forecast pans out, air quality levels in the long-term period should be Good to low Moderate.
Forecast updated by: Stephanie Hengesbach on Monday, July 10th, 2023
Next Forecast Update: Friday, July 14th, 2023