ASK THE METEOROLOGIST
“I’ve been hearing a lot about the Chetco Effect, what is it?”
The Chetco Effect is a term to define the phenomenon in which dry adiabatic heating increases the temperature of an air mass as it descends the slopes where the Chetco River creates a valley and to a lesser extent Gold Beach via the Rogue River. The dry adiabatic lapse rate is 10 degrees Celsius per 1 kilometer or 5.5 degrees Fahrenheit per 1,000 feet. If the parcel of air is dry than it warms at the dry adiabatic lapse rate on descent or cools by that rate during lift. The air gets funneled down towards Brookings and is able to warm up much more than the rest of the South Coast. This is the same phenomenon as the Santa Ana winds in southern California when you get dry air descending from the Great Basin.
The hottest day ever recorded in Brookings was due to the Chetco Effect which warmed the Brookings airport to 108 degrees on July 8, 2008!