FORECAST SUMMARY: Friday May 27th, 2022, through Tuesday May 31st, 2022

OZONE:

Ozone concentrations are expected to be in the mid-high Moderate range for portions of southern Michigan with the possibility of reaching USG levels.

PM-2.5:

PM-2.5 concentrations are expected to be Good throughout the weekend.

FORECAST DISCUSSION:

Changes to the forecast for the upcoming holiday weekend warranted an updated air quality forecast summary. Today, Friday, will see the Low pressure and associated frontal boundary that has brought rain to our area leave the region. Areas throughout Michigan will see temperatures in the mid-to-high 60s F with light NNW winds. Once the Low pressure exits the region early Saturday morning, a High-pressure sets up to our south providing light winds and ample sunlight. It is not until Sunday early morning when we see a true warmup. A warm front enters the region from the south and pushes temperatures into the upper 70s F and low 80s F. Dewpoint temperatures also look to increase with peak dewpoint being around the low-to-mid 60s F Sunday afternoon. Winds look to increase throughout the day on Sunday with the predominant wind direction being from the south. With this warm front, clouds look to be present throughout the day with some hours being completely overcast.

This trend continues into Monday with overcast skies for much of the morning but looks to open up as we go through the afternoon. Temperatures continue to rise with 80-degree F temperatures expected all throughout Michigan. Along with surface air temperatures, dewpoint temperatures are expected to rise as well, with peak dewpoint approaching 70 degrees F in some areas. Winds start out from the south and slowly shift to more southwesterly as we go through the late morning and early afternoon hours. As we go into the day on Tuesday, temperatures are expected to rise into the upper-80s F for the majority of Michigan with some northern Michigan areas in the low-80s F.

In terms of air quality, PM-2.5 does not look to be an issue whatsoever, Good concentrations are expected. The ingredients are looking to be present for ozone development in the latter half of the holiday weekend. Temperatures well into the 80s F and southwesterly winds are typically two of the main surface-level criteria we look for in surface-level ozone development. Along with surface-level, upper-level criteria such as temperature and wind direction help to forecast surface ozone as well. Upper-level temperatures in upper-teens to low-twenties Celsius are expected along with southwest winds—which are both surface ozone development indicators. There are still some uncertainties at this time, however. Cloud-cover models still show broken to overcast skies on Sunday and late-Monday morning. Also, high dewpoints sometimes inhibit the development of ozone, so dewpoints well into the upper-60s F for Sunday and Monday, could pose a “cap” for surface-level ozone development. Regardless of the uncertainties, Ozone is expected to be at least in the Moderate range, with some hourly-USG levels expected. I will be looking at the forecast and expected ozone ingredients throughout the weekend in case USG levels are expected to persist for longer than a few hours. If USG levels are expected to persist in the latter half of the forecast period, an updated forecast will be sent out with an associated Action Day.

EXTENDED FORECAST:

A cold front is expected to come through during the day on Wednesday, washing out the buildup of concentrations and drop temperatures into the mid-60s F.

Forecast updated by: Alec Kownacki, Friday May 27th, 2022

Next Forecast update: Tuesday May 31st, 2022