FORECAST SUMMARY: Tuesday, September 5, 2023, through Friday, September 8, 2023

Ozone: 8-hour average ozone concentrations are expected to be Good to Low Moderate.

PM-2.5: 24-hour average Fine Particulate concentrations are also expected to be Good to Low Moderate

FORECAST DISCUSSION: Tuesday may well be the last hot and humid day for summer 2023. Temperatures are expected to top out in the low 90’s in the southern half of the state with dew points in the mid-60’s.  With that level of temperature and humidity, it is possible to see popup thunderstorms during the afternoon.  A slow-moving front will bring an end to this episode of hot and humid weather during Wednesday and Thursday along a decent dose of precipitation.  Following the frontal passage, temperatures by the end of the week and into the weekend should be in the lower 70-degree range with mostly dry conditions.

The heat and humidity of the holiday weekend brought concerns about potentially elevated ozone, especially along the western lake shore counties.  While we did see numbers in that area reach the mid to upper 60 ppb range, we fortunately did not see any USG values.

As has been the pattern for most of this summer, Air Quality concerns have bounced between ozone problems and smoke problems, with occasional episodes where both have simultaneously been a problem.  As we get past the high ozone potential during the holiday weekend, we now look to smoke issues currently in the Plaines states.  A series of wildfires in the North Dakota and Montana are combining with nearby wildfires in Canada to present smoke problems in that area.  Fortunately, all the smoke models are in good agreement that for the next few days, the smoke should get no closer than western Minnesota and Iowa. 

As our ozone season winds down with shorter, cooler days, fine particulates in smoke are not limited by temperature, solar intensity, or season.  As such, we will keep a close eye on the smoke out west.  As that smoke currently does not look to travel this far east, I do not see a need to update this forecast before our regular weekend forecast update posted on Friday.

EXTENDED FORECAST: Air Quality should be generally Good to Moderate through the weekend.

Next Forecast Update: Friday, September 8, 2023