4 November 2021
Storm after storm has swept Northern California and the San Francisco Bay Area in recent weeks — and more rain is on the way in the coming days.
Many meteorologists are saying the region is in a “progressive weather pattern.” What does that mean?
“Essentially, a progressive pattern is a nerdy way of saying the storm door remains open,” National Weather Service forecaster Brian Garcia explained, referring to another term his colleagues use to describe active weather patterns marked by multiple storms.
Getting into the weeds of the “nerdy” science, a progressive pattern means the winds in the upper atmosphere, known as the jet stream, are generally aligned from west to east with no large north-to-south loops, pushing weather systems quickly across the country.
The inverse of a progressive pattern is a blocking pattern, where the weather remains stagnant over the same location for prolonged periods of time. In California, this most often happens when a ridge of high pressure hunkers down on the West Coast, sometimes remaining in place for weeks, and pushes storms away from California and toward the Pacific Northwest.
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