PA Ozone/PM2.5 Forecast
September 3, 2015
Date: Thursday, September 3, 2015
Thursday is an Air Quality Action Day for the Philadelphia metropolitan area for Code Orange (Unhealthy for Sensitive Groups; USG) ozone! Thursday will be another hot, humid, and hazy day. After a period of fog in the morning, mostly sunny skies and light surface will promote ozone formation. Particle concentrations will approach the upper Moderate range in the humid and stagnant air mass, with contributions from smoke transported from the western U.S. wildfires. A weak “back door” (north to south moving) cold front will approach Philadelphia in the evening, but it is not expected to produce widespread clouds or rain that would decrease ozone concentrations.
Temperatures will finally drop on Friday as winds turn onshore (northeasterly) and bring cooler and cleaner maritime air into the forecast area. It will still be humid, and particles will decrease but remain in the Moderate range. Scattered clouds and the chance for an afternoon thunderstorm will limit ozone to the low Moderate range. Saturday will be a pleasant start to the holiday weekend, with sunny skies, near average temperatures, and lower humidity. Both ozone and particles will return to the Good range under the influence of strong onshore flow.
Go to the new Air Quality Partnership of the Delaware Valley web site!