FORECAST SUMMARY: Monday September 18th, through Friday September 22nd, 2023

Ozone: Ozone concentrations are expected to be in the Good to Moderate range.

PM-2.5: PM-2.5 concentrations are expected to be in the Good to low-Moderate range.

FORECAST DISCUSSION: As this past weekend most definitely felt like Fall, we see a gradual warmup throughout this week for the majority of Michigan. We start off the week with two High-pressure systems dominating the region and look to hang around through the end of the work week. Surface winds look to be predominantly southerly with slight variations in the easterly and westerly direction throughout the week. These southerly winds are the reason for surface temperatures approaching, and even eclipsing, 80 degrees towards the end of the work week. Also thanks to the High-pressure systems, every day will see a fair amount of sunshine. As we approach the weekend, the High-pressures start to move off the east with a building low-pressure system setting up over the Great Plains, which will influence our weather towards the end of the weekend.

 In terms of air quality, PM-2.5 continues to be a non-issue compared to what was seen earlier in the summer. Southerly winds this week will also help keep any residual Canadian wildfire smoke to our north, hence why the PM-2.5 forecast is Good to low-Moderate. However, due to the High-pressure we will see this week, early morning stagnation could be possible in more populated areas due to morning commutes and low winds. For Ozone, we expect overall Good concentrations for this week mainly due to cooler temperatures than what produces high concentrations of Ozone and the fact of days becoming shorter and less overall energy coming from the sun. Although, with winds periodically being southwesterly in the latter half of the week, there may be some low-end Moderate Ozone concentrations more so towards west and southwest Michigan.

EXTENDED FORECAST: A change in airmass is expected towards the end of the weekend which will help clean out any buildup from the High-pressures this week. Overall air quality is expected to be Good.

Next Forecast Update: Friday, September 22, 2023