Forecast Discussion

Current daily average fine particulate levels are in the Code Yellow range in a swath from Charlotte through the Sandhills, the Triangle area, and the Coastal Plain. Ozone levels have risen into the Code Yellow range north of Durham but are holding in the Code Green range elsewhere this afternoon.

Thursday will be characterized by an upper ridge over the eastern US and a surface high drifting off the New England coast. Weak disturbances along the southwesterly flow aloft will help produce scattered showers again over the mountains, southern Piedmont, southern Coastal Plain. The generous cloud cover and moisture-rich air mass will keep ozone levels in the Green range statewide. Easterly low-level flow should help keep the northeastern and coastal counties in the Code Green range for PM2.5 tomorrow, but particle pollution will likely accumulate into the Yellow range elsewhere.

On Friday the diffuse frontal boundary will lift north as a warm front and winds will veer southwesterly; scattered showers are likely again but won’t be enough to cleanse the airshed. Moderate fine particulate values will persist throughout most of the state while ozone levels hold in the Green range. On Saturday, low pressure traversing the Great Lakes region will drag a cold front across the area. The unsettled weather will again keep ozone concentrations low, and an area of moderate daily average PM2.5 concentrations will persist in the interior ahead of the boundary.