FORECAST SUMMARY:
FORECAST SUMMARY: Friday, July 30th, 2021 through Monday, August 2nd, 2021
Ozone: Ozone concentrations are predicted to be mostly Good for most of the weekend. Winds out of the west-southwest Saturday may bring Ozone from over Lake Michigan to the shoreline but concentrations should not cross the 8-hour average Moderate threshold.
PM-2.5: PM-2.5 concentrations will be mostly Good as well with a north wind clearing the wildfire smoke from the region until Saturday. Wildfire smoke will enter the region Saturday which may present Moderate concentrations and will track southward but, will exit the region come Sunday afternoon.
FORECAST DISCUSSION:
Upper-level winds will be from the north for most of today, Friday, with winds shifting to more west-southwest flow come Saturday due to the low-pressure system to our north-northeast. As the low-pressure moves out of the area, winds return to a northerly flow Sunday. Upper-level temperatures will be cooler this weekend with temperatures barely approaching the teens, hovering around 10 degrees Celsius for much of the weekend. The combination of north winds and lower temperatures will inhibit the development of Ozone, which is why concentrations will be mostly Good. As mentioned above, the north wind will help with PM-2.5 concentrations as well as clearing out the area.
Surface winds follow similarly to upper-level winds with the flow coming from the north today, Friday, and into Saturday before winds shift to westerly flow as the pressure-system treks across Ontario. The shift to westerly flow may bring some hourly Ozone concentrations to Moderate, but overall, 8-hour average concentrations are expected to be Good. As mentioned above, the west wind on Saturday will return some smoke concentrations to the area and will present Moderate concentrations but will quickly exit the area as the winds shift to northerly on Sunday. Once the low-pressure exits the area, some rainfall may occur which will help with concentrations as well.
EXTENDED FORECAST:
The low-pressure system treks off to the East and opens the door for a High-pressure system to set up to the West with cooler temperatures. Concentrations are expected to remain Good going into early next week.