FORECAST SUMMARY
Friday, September 10th, 2021, through Monday, September 13th, 2021
OZONE: 8-hour average Ozone concentrations are expected to range between Good and Moderate through the forecast period.
PM-2.5: 24-hour average Fine Particulate concentrations will also range between Good and Moderate.
FORECAST DISCUSSION:
After a few cool days with isolated sprinkles, warmer conditions move in for the weekend. High pressure positions itself east of the region which will produce south/southwest winds later Friday into Saturday. With that, warmer temperatures return along with possible wildfire smoke over the region.
Air quality Friday morning is Good across the state and with the low background in place, Good levels should continue through the day. On Saturday, winds pick up in speed from the south/southwest and both surface and upper-level temperatures increase. Saturday seems to be the most likely day for higher ozone concentrations, primarily along the west Michigan lakeshore. A few hourly readings may reach low-end USG; however, considering the time of year and earlier sunset, 8-hour concentrations in the USG range are not anticipated. 8-hour Ozone Saturday should range from upper Good to upper Moderate across the state.
By late Saturday/early Sunday a cold front settles in from the northwest. Expect northerly winds north of the front and southerly winds south of the boundary. The position of the boundary should be across southern Michigan Sunday and Moderate ozone may develop near and south of the boundary, but clouds should hamper a significant increase. The boundary moves close to or just south of the state Monday. Warmer temperatures remain, but again clouds should keep ozone from reaching higher than Good to low Moderate.
For fine particulate, wildfire smoke is light over the region Friday; however, models show smoke plumes moving over the state as southerly winds develop. Also, the frontal boundary lingering close to the state Sunday/Monday could allow for a fine particulate buildup. At this time, it doesn’t look as if smoke will significantly increase fine particulate levels, but the combination of smoke and a front could cause Moderate readings, especially across the southern portion of the state. We are forecasting Moderate fine particulate across central and southern locations through Monday.
EXTENDED FORECAST:
Extended models show the boundary lifting north early next week with a cold front passing Tuesday. The Tuesday front should clean out any Moderate pollution levels from Sunday/Monday.
Forecast updated by: Stephanie M. Hengesbach
Next Forecast update: Monday, September 13th, 2021