National Weather Service United States Department of Commerce

Thunderstorms and Heavy Rainfall in the Mid-Atlantic; Fire Weather Concerns in the West

Thunderstorms are expected to bring heavy rain and potential significant flash and urban flooding to the Mid-Atlantic on Thursday, especially along the I-95 urban corridor. Dry conditions, gusty winds, and isolated dry thunderstorms will continue to bring a critical fire weather threat to the northwestern Great Basin into the interior Northwest through Thursday. 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.
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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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