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Significant and Catastrophic Flooding in the Pacific Northwest; Very Cold Temperatures in the Northern Plains

The atmospheric river over the Pacific Northwest will begin to subside today, but lingering rainfall will exacerbate ongoing catastrophic major river flooding, and landslides will continue across portions of western Washington and northwest Oregon for several days. Arctic air will plummet southward into the Northern Plains today, bringing cold air in the single digits to the region by Friday. Read More >

Overview

In the afternoon of August 8th, 2020, thunderstorms developed across eastern Wyoming and western South Dakota. These brought large hail and damaging winds to the area through the evening. One storm that developed over the Black Hills produced grapefruit-sized (4.5 inch) hail! As the storms shifted eastward, they formed a line, developing into a mesoscale convective system as more storms converged together. The main threat changed from hail to strong winds, with nearly 80 mph gusts reported across south central South Dakota. As the storms passed, magnificent mammatus was seen by many.  Image
Pactola (R. Strom)
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