PHILADELPHIA - The hazy, smoky skies that created bad air quality and vivid red sunrises and sunsets the last few days will be cleaned out Wednesday afternoon as gusty thunderstorms threaten the Delaware Valley.
NOAA's Storm Prediction Center has highlighted much of our region for a slight risk (level 2 out of 5) of severe weather Wednesday.
Scattered strong to severe thunderstorms are expected to develop along an approaching cold front by midday or early afternoon across eastern Pennsylvania and New Jersey, then expand in coverage across the rest of our area through the afternoon and early evening.
The main threat from these thunderstorms will be damaging wind gusts, with isolated large hail possible as well. The storms will push off the coast later Wednesday evening.
Wednesday's severe thunderstorm outlook. (NOAA's Storm Prediction Center)
Before the thunderstorms arrive, air quality will remain poor across the Delaware Valley due to wildfire smoke originating more than 2,000 miles away in the western United States and western Canada.
Air quality alerts remain in effect for much of the region on Wednesday. As of midday Wednesday, the Air Quality Index (AQI) in Philadelphia was considered unhealthy for sensitive groups, or code orange.
The Delaware Valley Regional Planning Commission and the Pennsylvania Department of Environmental Protection have issued a code orange air quality alert for the Philadelphia metro area and the Lehigh Valley/Berks County area, respectively.
Additionally, the New Jersey DEP has issued a code orange air quality alert day Wednesday for Burlington, Camden, Gloucester, Mercer, Middlesex, Monmouth and Ocean counties.
This means air pollution concentrations within our region may become unhealthy for sensitive groups. These groups include children, the elderly and people suffering from asthma, heart disease or other lung diseases. The effects of air pollution can be minimized by avoiding strenuous activity or exercise outdoors.
NOAA's HRRR-Smoke forecast model shows the haze and smoke clearing out by Wednesday night following the passage of the cold front responsible for the gusty thunderstorms.