For the past week, high pressure domes over the Desert Southwest and off the Southeast Coast, separated by a deep low pressure trough through the middle of the U.S., have brought extreme weather to portions of the country while producing a pleasant, relatively cool summer across the Heartland.
Beneath the domes, air is sinking, heating up and spreading outward, creating a clockwise spiral of wind along their rims. The southwestern dome has produced excessive heat; the sinking air dries out as well as heating up, negating cloud formation and intensifying both solar radiation and evaporation. Record or near record highs have been set across the region and Pacific storm systems have been shunted to the north, allowing wildfire conditions to worsen.
In the Southeast, the winds around the Bermuda High are sweeping copious moisture onshore from the Gulf of Mexico and the Atlantic Ocean. Interacting with the low pressure trough, which provides the lift, this soupy air has ignited thunderstorms; training across the same areas, the storms have dropped up to 20 inches of rain in parts of western Florida and southwestern Alabama. Farther north, most of the Piedmont and Coastal Plain set precipitation records for the month of June and, unless the current weather pattern breaks down, the same may occur in July. Of course, those of us beneath the relatively cool central trough would be pleased to see our mild summer continue.
