Showalter Index Calculator

Lake Effect Snow through Friday; Heavy Rain, Thunderstorms and Mountain Snow in California

Periods of moderate to heavy lake effect snow will continue through Friday downwind of Lake Erie and Ontario. Several additional inches of accumulating snow are expected. A Pacific storm will bring heavy rain and mountain snow across California, the Southwest and Intermountain West today. Isolated severe thunderstorms and scattered flash flooding is possible across parts of southern California. Read More >

Showalter Index

Enter the temperatures that you would like:

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.

Lake Effect Snow through Friday; Heavy Rain, Thunderstorms and Mountain Snow in California

Showalter Index

by Tim Brice and Todd Hall

Enter the temperatures that you would like:

What does my answer mean?

What is the formula for the Showatler Index?