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Cold Front Moving Through the Northeast U.S. Monday; Atmospheric River to Impact the Pacific Northwest Midweek

A cold front will cross the Great Lakes and Northeast U.S. through Monday with gusty winds and areas of rain showers. A strong atmospheric river is expected to move into the Pacific Northwest by midweek bringing a threat for moderate to heavy rainfall, gusty winds, and mountain snows for parts of Washington, Oregon, northern California, and the Sierra Nevada. Read More >

Overview

From the evening of May 20th through mid afternoon on May 21st, several waves of thunderstorms produced tornadoes, damaging winds with gusts up to 90 mph, hail up to tennis-ball size, and extremely heavy rainfall, which resulted in considerable flash flooding and river flooding.

Six tornadoes (5 EF0 and 1 EF1) occurred with a fast-moving line of thunderstorms that moved through eastern Nebraska and southwest Iowa during the early morning hours on the 21st. An additional 4 tornadoes occurred with a second round of thunderstorms (supercells) that formed over far eastern Nebraska and tracked through southwest Iowa during the late morning and early afternoon hours on the 21st. 

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Radar loop from 4 PM on May 20th through 3 PM on May 21st
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