FORECAST SUMMARY: Monday, August 21, 2023, through Tuesday, August 22, 2023
PM-2.5: 24-hour average Fine Particulate levels will range between upper Good and low Moderate.
OZONE: 8-hour average Ozone concentrations are expected to be Good to Moderate.
FORECAST DISCUSSION: A weak cold front moved through late Sunday/early Monday bringing in northeasterly winds and less humid conditions. Monday will feel more comfortable than Sunday with lower dew points and temperatures in the upper 70s to low 80s. A switch back is in store, however, as heat and humidity build to our west Monday and Tuesday. Surface high pressure north of the state tracks east, as a boundary lifts north Wednesday. This changes winds back to a southerly direction by mid-week bringing the heat and humidity east and into Michigan. Overnight storms are also a possibility both Monday night into Tuesday morning, and more so Tuesday night into Wednesday morning. Current forest models show these systems missing the southwest portion of the state both periods, keeping conditions dry.
High clouds and northeasterly/easterly winds through Tuesday should keep pollution levels in check with readings higher than Moderate not anticipated for either ozone or PM2.5. Southerly winds developing Wednesday, coupled with increases in both surface and upper-level temperatures, brings a threat for increased ozone. Ozone models are picking up on this as well, showing increases into the Unhealthy for Sensitive Groups range, mostly in the southwest, by Wednesday. A forecast update will be done Tuesday morning to evaluate updated models, and to determine if an Action Day for ozone will be necessary Wednesday.
Wildfire smoke maps were reviewed and there is still a plume lingering over the region. Thankfully, the smoke has for the most part remained at upper levels only resulting in small PM2.5 increases. Daily averages of PM2.5 were in the upper Good to low Moderate range this past weekend. Smoke models do show a bit of an improvement Tuesday, but the plume looks to linger, mostly at upper levels, this week. With smoke remaining overhead, PM2.5 should continue in the upper Good to low Moderate range. Along with ozone trends, we will be keeping an eye on smoke models and PM2.5 readings, making updates if necessary.
EXTENDED FORECAST: The warm-up Wednesday and Thursday may be short-lived due to a cold front expected to pass through late in the week. If this pans out, the threat for increased ozone should come to an end Friday.
Next Forecast update: Tuesday, August 22, 2023