FORECAST SUMMARY: Saturday, September 2, 2023, through Sunday, September 3, 2023
Ozone: 8-hour average Ozone concentrations are forecast to range between Good and Moderate; with isolated USG possible.
PM-2.5: 24-hour average Fine Particulate levels are also expected to be in the Good to Moderate range.
FORECAST DISCUSSION: Clouds and scattered precipitation move from north to south across the state today, Saturday, as a boundary sinks through. This system will keep air quality from reaching higher than Moderate for ozone while some low-Moderate PM2.5 is possible. The forecast is still on track for a warmup Sunday through the Labor Day holiday. High pressure dominates at the surface and an upper-level ridge builds over the area bringing in southerly winds and warm temperatures. Dew points also increase; therefore, conditions will feel muggier outside.
As for air quality, there is still some question on ozone levels Sunday. Models are keeping higher concentrations confined to the west Michigan lakeshore. While more sunshine is expected tomorrow compared to today, Saturday, forecast models are picking up on some clouds as well. One thing is still on track and that’s southerly winds at the surface and upper levels bringing in warmer temperatures. At this point, we feel widespread USG ozone is unlikely Sunday in the west, and an Action Day is not warranted. Based on forecast models, higher wind speeds also hamper significant ozone development helping keep ozone Moderate. Current pollution trends will be evaluated tomorrow morning and if this changes, the Moderate forecast will be updated to USG triggering EnviroFlash notifications.
There have been some increases in PM2.5 this morning into the low-Moderate range and we expect this trend to continue. Concentrations over the next few days should range from upper Good to low Moderate.
EXTENDED FORECAST: Extended models show a pattern change mid-week with chances for precipitation and cooler conditions. This will improve any pollution increases seen earlier in the week.
Next Forecast Update: Sunday, September 3, 2023