Thursday, June 20th, 2019 through Monday, June 24th, 2019
Ozone: 8-hour Ozone concentrations will range between Good and Moderate through the forecast period.
PM-2.5: 24-hour Fine Particulate concentrations will also range from Good to Moderate.
Precipitation across lower Michigan will finally end Thursday afternoon as the storm system tracks east. This will be replaced with weak high pressure for Friday which will bring in dry conditions and warmer temperatures. The dry conditions may be short-lived, however, as an active weather pattern is expected for this weekend into early next week. Warm temperatures will remain in place through the period.
Cool, wet conditions Thursday will allow for Good air quality. More in the way of sunshine is expected Friday and surface temperatures will increase, but northerly winds and cooler upper level temperatures will hamper ozone development. Ozone is expected to range between Good and Moderate, and fine particulate will be mostly Good with a few low Moderates possible in the southeast. Storm chances may come into play early Saturday as a complex is expected to track southeast from Wisconsin early in the day. The exact track of this isn’t certain and parts of the state may remain dry. Upper level temperatures again remain lower, especially over the southeastern portion of the state. At this time a significant increase in ozone is not expected with both ozone and fine particulate levels ranging from upper Good to Moderate.
By Sunday, winds at the surface and upper levels turn more southwesterly and warmer temperatures move in. This is more conducive for ozone, but a warm front will also be tracking up from the south bringing with it clouds and scattered storms. Ozone may reach Moderate in areas with more hours of sunshine but levels higher than Moderate are not expected; more widespread Moderate fine particulate can be expected. Forecast maps will be evaluated again Friday morning and this forecast will be updated if we feel pollution levels will increase higher than what is currently anticipated.
The warm front, followed by an associated cold front, will keep storm chances through Monday. Ozone may reach Moderate in a few locations if the sun breaks out, otherwise levels should be Good. Fine particulate through early next week will range from upper Good to low Moderate.