Saturday is an Air Quality Action Day! Warm temperatures, increasing humidity, mostly sunny skies and southerly winds, coupled with recirculation of today’s ozone, will push air quality into the Code Orange range. PM concentrations will rise as well but remain in the moderate range.
Poor air quality is likely to extend into Sunday. A weak cold front will arrive but is unlikely to significantly change the air mass characteristics. Temperatures will reach the low 90’s F and ozone will remain in the Code Orange range. A bit cooler and less humid on Monday. Air quality will improve but a threat of Code Orange ozone remains. To follow air quality in PHL between forecasts: "aqforecast" at www.twitter.com -Ryan/Bradbury