FORECAST SUMMARY: Tuesday, July 6th, 2021, through Monday, July 12th, 2021
OZONE: 8-Hour average Ozone concentrations are expected to be Moderate on Monday then transitioning to mostly Good to Moderate during Tuesday and for the remainder of the forecast period.
PM-2.5: 24-hour average Fine Particulate concentrations are expected to be Good to Moderate throughout the forecast period.
FORECAST DISCUSSION:
The 4th of July holiday weekend is ideally hot and dry, but not too uncomfortable. The past weekend, temperatures reached the 90-degree mark but did not feel too oppressive.
As high pressure slipped eastward through the weekend, surface and upper-air winds were favorable through Saturday, and Air Quality Good. As the center of the high-pressure ridge passed by on Sunday, surface winds turned to the southwest. With that wind direction, especially this time of year, we tend to get concerned. However, anyone who spent time outside probably noticed a thick haze over the sky which filtered out the harshest of the sun’s rays. That haze was a thick layer of smoke over much of the Midwest courtesy of Canadian wildfires. The wind shift on Sunday thinned out the layer of smoke and we did see a creep in the ozone numbers during Sunday and Monday, but it got no worse than Moderate.
Fine particulates over a 4th of July holiday weekend always tend to run high due to fireworks. While this weekend was no different, I do not think it was as bad as some years in the past. That said, the Dearborn monitor did creep into the USG range on Sunday, but the rest of the state remained Moderate. I did notice some of the northern monitors starting to creep into the Moderate range earlier in the weekend but that was likely the smoke layer mixing down to the surface.
Tuesday will still experience heat and plenty of Moderates for ozone and fine particulates, but the threat of elevated levels of ozone should be low and confined to the southwest corner of the state. As a cold front drops through on Wednesday, that will eliminate any additional threats for the rest of the week. We will be in a cleaner, cooler air mass and have Good Air Quality. We will likely still see a smoke haze aloft and it will be interesting to see if any of that mixes down to the surface.
Another warm-up is not expected until early next week, in advance of a low-pressure system. As such, this forecast should be good through the weekend.
EXTENDED FORECAST:
Air Quality should be Good to Low Moderate going into the next work week.