FORECAST SUMMARY: Monday, September 25, 2023, through Friday, September 29, 2023
Ozone: 8-hour average Ozone concentrations remain Good through the forecast period.
PM-2.5: 24-hour average Fine Particulate levels will range between Good and Moderate.
FORECAST DISCUSSION: Two systems will influence weather conditions this week. High pressure to our northeast keeps dry conditions further north while a slow-moving low-pressure area traveling from Minnesota Monday to southwest Michigan early Thursday produces a cool, showery pattern for most of the lower peninsula. High temperatures through the period will range mostly in the middle and upper 60s with an east/southeasterly wind flow in place.
While not as prevalent as this past summer, wildfires persist in Quebec and Ontario, Canada. Looking back to Sunday, smoke over the region did produce low Moderate PM2.5 across some northern and central monitors. Satellite imagery Monday morning shows a smoke plume dropping southwest towards the upper Great Lakes region. The smoke plume moving towards northern locations may allow for Moderate PM2.5 through Wednesday. We do not anticipate daily averages of PM2.5 to reach higher than Moderate, but this is something we will monitor, and the forecast will be updated if conditions worsen. Overall, daily averages of PM2.5 levels should range between middle Good and middle Moderate this week.
On Thursday, some showers linger in southern areas, but high pressure becomes more dominant for the end of the week. Winds become more southerly and warmer/dry conditions are anticipated. Moderate PM2.5 may persist in the south, but smoke plume models show any lingering plumes pushing north of the area. Concentrations of PM2.5 should end the forecast period in the Good to low Moderate range.
Cooler temperatures, precipitation across much of the state, and a lower sun angle this time of year should keep ozone Good through the week.
EXTENDED FORECAST: Extended models show dry weather and warmer conditions for the coming weekend. Pollution levels may increase towards Moderate late in the forecast period.
Next Forecast Update: Friday, September 29, 2023