FORECAST SUMMARY:

Friday, June 26th, 2020 through Monday, June 29th, 2020

OZONE: 8-Hour average Ozone concentrations will range between Good and Moderate; a few USG readings are possible early next week.

PM-2.5: 24-hour average Fine Particulate concentrations will range from Good to low Moderate.

FORECAST DISCUSSION:

Strong storms are forecast to move through the state Friday late afternoon through the overnight hours as a cold front drops in from the northwest. This boundary sinks just south of the state Saturday, possibly triggering more showers and storms across southern locations. Sunday into Monday this boundary slowly sinks south into the Ohio valley as high pressure moves over the northern Great Lakes region. Behind this boundary temperatures do not fall and highs above normal are expected as we move into next week.

As for air quality, ozone has been Good the past few days and with clouds moving in I am expecting mostly Good readings again Friday. The boundary drops south Saturday, and temperatures remain warm; however, clouds starting the day and a west/northwesterly wind at the surface and upper levels should keep ozone between Good and low Moderate. The difficulty in the forecast for early next week is the exact placement of the Saturday boundary and how far south it gets.

Models show more in the way of sunshine Sunday while some clouds may linger further south. I am expecting ozone readings to increase from Saturday with most locations into the Moderate range Sunday. By Monday, winds at the surface and upper levels look to become east/southeasterly as high pressure moves northeast of the state. For now, I am going with a Moderate forecast for ozone Monday with a few locations having the possibility to reach USG; mainly along the west Michigan lakeshore if afternoon lake breezes develop. We will evaluate weather maps Sunday morning and will update this forecast if we feel widespread USG levels become a threat for Monday.

Fine particulate has been running mostly Good and levels through early next week will range from middle Good to low Moderate.

EXTENDED FORECAST:

Extended models keep us in the same weather pattern as we continue towards mid-week. Without an airmass change, the warm, dry, sunny conditions will bring a threat for increased ozone. This threat for higher ozone concentrations will be detailed in the Monday forecast update, or Sunday if one is necessary.

Forecast update by: Stephanie M. Hengesbach June 26th, 2020.
Next forecast update: Monday, June 29th, 2020