National Weather Service United States Department of Commerce

Prolonged Atmospheric River Will Impact the Northwest Early this Week

A weather system in the Pacific Northwest will produce rain throughout the day, before a potent atmospheric river produces a prolonged round of heavy rainfall, widespread urban and river flooding, and high elevation snow to the region Monday through Wednesday. Showers and thunderstorms may produce isolated damaging winds, a brief tornado, and locally heavy rainfall across parts of Florida today. Read More >

Automatically generated image showing areas of the significant tornado parameter.

 

Thumbnail of an automatically generated image showing areas of the significant tornado parameter. Thumbnail of an automatically generated image showing areas of the significant tornado parameter. Thumbnail of an automatically generated image showing areas of the significant tornado parameter.
Hour - 1 Hour - 2 Hour -3

4 Panel Display | Animated Loop

Significant Tornado (SigTor) 

A composite index that includes 0-6 km bulk wind shear, 0-1 km storm-relative helicity, surface based CAPE, surface parcel CIN, and surface parcel LCL height. Values greater than 1 are indicative of increased potential of significant tornadoes.

The contours are the Lifted Condensation Level or LCL.  A lower LCL typically increases tornadic risk because it is indicative of air parcel acceleration occurring closer to the surface. 

 

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