FORECAST SUMMARY:
THURSDAY, MAY 20TH, 2021 THROUGH FRIDAY, MAY 21ST, 2021
OZONE: 8-Hour average Ozone concentrations are expected to range from Good to Moderate with USG possible in the west and southeast, especially Friday.
PM-2.5: 24-hour average Fine Particulate concentrations will range between upper Good to middle Moderate.
FORECAST DISCUSSION:
As expected, warm and humid weather is in place across the state. Ridging at the surface and upper levels will keep this trend going the next few days. Cloud cover has been the difficult part to the forecast and that holds true as we move towards the weekend. Less clouds than expected were seen Tuesday and three monitors in the eastern part of the state reached low-end USG. Wednesday concentrations improved and levels did not reach higher than Moderate.
After evaluating most recent forecast maps we feel conditions Friday are conducive for ozone development in parts of the state; therefore, we are issuing Air Quality Action Day Advisories in both west and southeast Michigan. Increased temperatures, southwest winds, and less cloud cover than expected earlier this week is what lead to our decision to issue the Action Days. In other parts of the state, while it will be warm and muggy, clouds will be more prevalent and there are chances for scattered precipitation which should keep ozone in the Good to Moderate range.
Fine particulate has been a mix of upper Good to middle Moderate and without a change in airmass anticipated, readings in this range will continue.
EXTENDED FORECAST:
Extended forecast models show warmer conditions as the weekend begins, but a frontal boundary may bring precipitation chances Sunday. With the threat for increased ozone continuing Saturday, we will update this forecast tomorrow to detail weekend air quality conditions.