National Weather Service United States Department of Commerce

Strong Storm System To Impact The West

A large, strong and moist Pacific storm system will impact a good portion of the West on Friday through the upcoming weekend. Heavy rain, strong winds, heavy mountain snow and rough surf can be expected. The heavy rain may result in some flash flooding on Friday and Saturday across northern portions of California and southwestern Oregon, especially near recent burn scar areas. Read More >

Showalter Index

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

 

What is the formula for the Showatler Index?