Showalter Index Calculator

Arctic Chill in the East Followed by Strong Clipper Storm

Arctic air will continue below normal temperatures across the eastern half of the U.S. into Tuesday with heavy lake effect snow taking a short reprieve across the Great Lakes. A strengthening clipper storm will track north of the Great Lakes midweek with a widespread snow and gusty to strong winds through the region and into the Northeast U.S. followed by the potential for more lake effect snow. 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.

Arctic Chill in the East Followed by Strong Clipper Storm

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?