Forecast Discussion

Date: Sunday, July 12, 2020

Forecast Valid: Monday, July 13, 2020

Today's Air Quality Conditions: Hourly ozone concentrations have temporarily risen into the Code Yellow range at the Mt. Mitchell and Linville Falls higher elevation monitors, and also are rising into the Code Yellow range in the Charlotte region. For a display of the most recent air quality conditions throughout the remainder of this afternoon, please visit the US EPA's AIRNOW web site.

General Forecast Discussion: Tomorrow, a shortwave and attendant vort max will swing across the areas sometime during the morning into the afternoon, and could be the catalyst for more widespread afternoon showers and storms, especially in the Sandhills and Coastal Plain. Ozone levels will be highly dependent upon the location and coverage of showers and storms, but with the expected coverage likely to be higher in the east, will continue to project Code Yellow ozone only in the Charlotte region -- where it is at least possible that shower and thunderstorm activity stays east of -- and Code Green range elsewhere. Particle pollution levels are expected to continue to remain predominantly in the Code Green range.

Outlook: On Tuesday into Wednesday - a weak, dissipating front will attempt to cross the areas overnight Monday into Tuesday behind the departing short wave. However, no discernible change in air mass is expected. Behind this upper shortwave, a weak area of high pressure will develop over the Ohio Valley/Great Lakes region and gradually strengthen as it builds eastward over New England. The primary effect on NC will be to keep an easterly component to the wind direction, which may introduce just enough surface moisture to enhance low and mid level clouds to at least some extent. Conversely, winds are expected to remain light -- which depending on the amount of cloud coverage -- may yet allow ozone levels to rise into the Code Yellow range in the usual metropolitan regions.

Extended Air Quality Outlook
Forecast Day
AQI Range
Category Range
Monday 45-58 Green-Yellow
Tuesday 45-71 Green-Yellow
Wednesday 45-71 Green-Yellow

The forecast Air Quality Index value for each pollutant represents the highest value expected within the forecast region, so some areas and monitors may see lower values. We use the best information and techniques available to ensure the quality and accuracy of the forecasts we provide to the public.

(McLamb - NC Division of Air Quality)


Date: Saturday, July 11, 2020

Forecast Valid: Sunday, July 12, 2020

Today's Air Quality Conditions: Air quality levels remain in the Code Green range statewide this afternoon. For a display of the most recent air quality conditions throughout the remainder of this afternoon, please visit the US EPA's AIRNOW web site.

General Forecast Discussion: Tomorrow, a mean trough will have developed over the east coast with another shortwave digging through the Ohio Valley. Height falls and potential PVA by Sunday afternoon could trigger some isolated showers and storms especially in the western part of the state. However, it appears coverage will remain low and cloud cover may not be sufficient to prevent ozone formation from occurring at a rate that would allow concentrations to rise into the Code Yellow range in the metropolitan areas. Monday, a shortwave and attendant vort max will swing across the areas sometime during the morning into the afternoon, and could be the catalyst for more widespread afternoon showers and storms, especially along in the Sandhills and Coastal Plain region. Ozone levels will be highly dependent upon the location and coverage of showers and storms, but with the expected coverage likely to be higher in the east, will continue to project Code Yellow ozone in the Charlotte region.

Outlook: A weak, dissipating front will attempt to cross the areas overnight Monday into Tuesday behind the departing short wave. However, no discernible change in air mass is expected. Winds are expected to remain light, and ozone levels may rise again into the Code Yellow range in the usual metropolitan regions.

Extended Air Quality Outlook
Forecast Day
AQI Range
Category Range
Sunday 45-67 Green-Yellow
Monday 45-64 Green-Yellow
Tuesday 45-64 Green-Yellow

The forecast Air Quality Index value for each pollutant represents the highest value expected within the forecast region, so some areas and monitors may see lower values. We use the best information and techniques available to ensure the quality and accuracy of the forecasts we provide to the public.

(McLamb - NC Division of Air Quality)