Showalter Index Calculator

Series of Storms to Impact the West Coast

Powerful Pacific storms will keep conditions wet and windy for much of the West, especially, from northern California to western Washington. Heavy rains may produce flooding early to mid week. Heavy snow will make travel difficult from the Cascades to the northern Rockies. Snow showers continue near the Great Lakes, otherwise, dry conditions and gusty winds can be expected for much of the East. Read More >

Showalter Index

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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.

Series of Storms to Impact the West Coast

Showalter Index

by Tim Brice and Todd Hall

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What is the formula for the Showatler Index?