FORECAST SUMMARY: MONDAY, JULY 3RD, THROUGH TUESDAY, July 4TH, 2023
OZONE: Ozone concentrations will range mostly Moderate Monday with a range of Moderate to USG Tuesday.
PM-2.5: 24-hour average Fine Particulate through the period should range mostly Moderate.
FORECAST DISCUSSION:
As anticipated, ozone concentrations look to begin increasing Monday and more so Tuesday as winds switch to a southerly direction. Contributing to the threat for increased ozone will be plentiful sunshine, southerly winds, and warmer temperatures both at the surface and upper levels. Maximum 8-hour ozone Monday should remain generally Moderate, with isolated USG possible along the western lakeshore and in the southeast. The threat for higher concentrations remains Tuesday and being the second day with this set-up, increased ozone in the Unhealthy for Sensitive Groups (USG) range is more likely. Therefore, we are issuing an Action Day for Tuesday covering the western lakeshore areas and the southeast portion of the state.
Overall PM2.5 levels continue to improve as wildfire smoke has less ground level influence over the region. We anticipate daily averages of PM2.5 to remain generally Moderate, however, localized higher concentrations can be expected due to fireworks displays in celebration of the 4th of July. Any evening hourly PM2.5 increases should improve by late morning/early afternoon the following day.
This forecast will be updated tomorrow, Tuesday, July 4, to look ahead at potential Ozone issues for Wednesday.
EXTENDED FORECAST: Forecast models show sunny and warm conditions continuing Wednesday before a frontal boundary brings precipitation into the forecast. The possibility exists for another day of increased ozone on Wednesday; therefore, this forecast will be updated tomorrow to determine if the Action Day will need to be continued.
Next Forecast Update: Tuesday, July 4, 2023