FORECAST SUMMARY: Monday, September 4, 2023, through Tuesday, September 5, 2023
Ozone: 8-hour average Ozone concentrations are forecast to range between Good and Moderate; with isolated USG levels possible.
PM-2.5: 24-hour average Fine Particulate levels are expected to be in the Good to Moderate range.
FORECAST DISCUSSION: This Labor Day features sunshine and warm temperatures into the 90s. By Tuesday, dew points increase ahead of an approaching system. Warm and muggy conditions will be in place, however, more prevalent cloud cover and small chances for storm development keep ozone from significantly increasing. Ozone concentrations Sunday ranged upper Good to upper Moderate, and as expected, highest readings were in west Michigan along the lakeshore. Hourly concentrations Monday morning at western locations were running lower than they were this time yesterday, but since Sunday’s max 8-hour levels were close to USG, we decided to increase the forecast from Moderate to USG for our Grand Rapids forecast area for Monday; this forecast area includes the lakeshore areas from Muskegon to Holland. Across the rest of the state Moderate readings are anticipated. With increased clouds and precipitation chances, Good to Moderate ozone is to be expected Tuesday.
Regarding PM2.5, smoke models show any plumes staying north and west of the region the next few days. Hourly concentrations at some locations were ranging low Moderate Monday morning. Increased wind speeds should keep readings from climbing much through Tuesday; daily average PM2.5 concentrations should remain upper Good to low Moderate.
EXTENDED FORECAST: Extended models continue showing a pattern change mid-week with chances for precipitation and cooler conditions. Pollution levels will be mostly Good during this period.
Next Forecast Update: Tuesday, September 5, 2023