TCEQ meteorologists make daily Ozone Action Day (OAD) forecasts for 17 major areas in Texas.
The Ozone Action Day forecast seasons are based on when each region is likely to experience elevated ozone concentrations. Each forecast predicts whether ozone levels for the following day in an area are expected to reach or exceed the EPA’s AQI Level Orange — an eight-hour average of 71 parts per billion or a one-hour average of 125 ppb.
TCEQ meteorologists use a set of criteria from historic meteorological data, ozone measurements, and ozone prediction models to make these predictions. When they forecast an Ozone Action Day, TCEQ meteorologists contact the National Weather Service, which then broadcasts the information across its “weather wire.” TCEQ also contacts officials in affected areas so that local community clean air coalitions can notify their media, government, business, and industry. Ozone Action Days are issued, in most cases, by 2 p.m. local time and are valid for the next day.