National Weather Service United States Department of Commerce

Back-to-Back Pacific Storms to Impact the West Coast; Heavy Snow in the Central Appalachians

Back-to-back powerful Pacific storm systems to impact the Pacific Northwest and northern California through the end of this week with heavy rain, flooding, strong winds, and higher elevation mountain snow. A strong, long-duration atmospheric river will accompany the Pacific storms, bringing excessive rainfall and flash flooding to southwest Oregon and northwest California through the week. Read More >

Automatically generated image showing areas of surface-1km vertical shear.

 

Thumbnail of an automatically generated image showing areas of surface-1km vertical shear. Thumbnail of an automatically generated image showing areas of surface-1km vertical shear. Thumbnail of an automatically generated image showing areas of surface-1km vertical shear.
Hour - 1 Hour - 2 Hour -3

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Shear (0-1km) 

Surface-1-km Vertical Shear is the difference between the surface wind and the wind at 1-km above ground level. These data are plotted as vectors with shear magnitudes contoured. 0-1-km shear magnitudes greater than 15-20 knots tend to favor supercell tornadoes.

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