5/21/2021 Forecast Update
FORECAST SUMMARY:
FRIDAY, MAY 21st, THROUGH MONDAY, MAY 24, 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. The rest of the period should range between Good and Moderate.
PM-2.5: 24-hour average Fine Particulate concentrations will range between upper Good and middle Moderate.
AIR QUALITY ACTION DAY ADVISORY FOR FRIDAY, MAY 21ST, FOR THE FOLLOWING COUNTIES:
ALLEGAN, BERRIEN, CASS, KENT, MUSKEGON, OTTAWA, and VAN BUREN
FORECAST DISCUSSION:
Warm and humid weather lasts through the weekend; however, a frontal boundary sinks in from the north and settles into southern portions of the state Saturday. This boundary should provide more in the way of cloud cover and chances for scattered precipitation. The boundary lingers over the region early next week keeping partly to mostly cloudy skies and scattered precipitation.
As for air quality, less cloud cover is expected Friday and the threat for increased ozone in the west and southeast remains. Warm/muggy conditions continue Saturday through Monday, but more clouds, scattered precipitation, and wind shifts to the west/northwest Saturday/Sunday should hamper significant increases in ozone. Isolated areas that end up with more sunshine could possibly reach low-end USG, but the threat is not high enough at this time to warrant action days. We are keeping a Moderate ozone forecast Saturday through Monday and we will evaluate forecast maps this weekend. If conditions worsen where we feel increased ozone is likely, this forecast will be updated.
Fine particulate has been a mix of upper Good to middle Moderate and without a change in airmass anticipated, mostly Moderate readings continue.
EXTENDED FORECAST:
Extended forecast models finally hint at a change in airmass around mid-week with a stronger front passing through. Until then, expect warmer conditions, scattered precipitation, and mostly Moderate ozone and fine particulate.