John Wheeler, WDAY, Published August 22 2012
Weather Talk: Persistent weather pattern leads to drought conditionsA letter came into the weather office this week asking about the power and strength of the high-pressure system that has been causing the drought across the central United States. Drought, or any kind of persistent weather pattern, is caused not so much by a terribly strong weather system but by a very persistent one.
A long period with limited rainfall is the result of steering currents in the region guiding most of the storms elsewhere. It can also be the result of those steering currents just being weak over the region. This spring and summer, the polar jet stream, the primary current for storms across North America, has been weaker and displaced farther northward than it has been in most recent years. This has caused a lack of rainfall and a reduction in severe thunderstorms, along with an abundance of sunshine.
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