Forecast Discussion

Ozone levels have risen into the Code Yellow range in the Triangle and north to the Triad, as well as in the Fayetteville metro area. Current daily average PM2.5 levels are in the Code Yellow range throughout most of the state this afternoon.

On Friday, low-level winds will veer southerly as North Carolina becomes situated between an offshore surface high and an area of low pressure lifting over the Great Lakes region. The warm, moist air mass combined with some weak shortwave disturbances passing overhead will, as in the past couple days, allow for scattered showers and storms to develop across the state. The southeastern US airshed has been characterized by moderate PM2.5 values for several days and this will not change on Friday, given the localized nature of potential storms. Max 8-hour average ozone concentrations should again hold in the Code Green range, inhibited by the moisture and the cloud cover.

The attendant cold front of the aforementioned low will begin to cross the state from the northwest on Saturday evening. Prior to that, rainy southwest flow will persist. Moderate PM2.5 concentrations are expected in much of the Piedmont and western Coastal Plain ahead of this frontal passage. Ozone may rise a bit behind the front as skies clear, but overall should remain in the Green range. Once the front clears the state by Sunday, high pressure will build in again and the day will be sunny and dry. Both ozone and PM2.5 concentrations should drop down to the Code Green range for the day on Sunday.