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 convective inhibition.

 

Thumbnail of automatically generated image showing areas of convective inhibition. Thumbnail of automatically generated image showing areas of convective inhibition. Thumbnail of automatically generated image showing areas of convective inhibition.
Hour - 1 Hour - 2 Hour -3

4 Panel Display | Animated Loop

CIN 

The image is a surface based measurement of Convective INhibition (CIN) or what is sometimes more commonly referred to as the strength of the cap.  The value is capped off at 500 J/KG.  In cases where there is no surface based CAPE available this parameter is set to 500 J/KG.

The yellow contours are the Lid Strength Index (LSI).  This is another measure of how strong the cap is.  It shows the thermal difference between a lifted surface parcel and the warmest part of the cap.  Higher values indicate a more stable layer.

In general, the Cap is said to be breakable when CIN is 30 J/Kg or less and/or the LSI is 2 degrees or less.  A negative LSI is rare, but is indicative of freely buoyant low level instability.

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