National Weather Service United States Department of Commerce

Heavy Rain and Isolated Severe Thunderstorms in the South

Excessive rainfall will continue to bring localized flash, urban, and small stream flooding, along with new and renewed river rises over the northern Gulf Coast into this afternoon. Isolated strong to severe thunderstorms are possible today across parts of southeast Alabama, southern Georgia and portions of north and northeast Florida. Read More >

Showalter Index

by Tim Brice and Todd Hall
 
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Enter the 500 millibar parcel temperature: °C Answers:
Enter the 500 millibar environmental temperature: °C

What does my answer mean?

Showalter Index greater than 0: Stable, but weak convection possible for SI = 1-2 if strong lifting is present.
Showalter Index between 0 and -3: Moderately unstable.
Showalter Index between -4 and -6: Very Unstable.
Showalter Index between less than -6: Extremely Unstable.

 

What is the formula for the Showatler Index?