National Weather Service United States Department of Commerce

Disturbance Along North Carolina Coast; Severe Storms in the Central U.S.; Widespread Heat Concerns

The National Hurricane Center is monitoring an area of low pressure just offshore of North Carolina for tropical or subtropical development. Heavy rain, flooding and gusty winds are possible along coastal sections of the Mid-Atlantic and Northeast the next few days. Severe storms are likely today in the Central U.S. and heat related products extend from the Southwest into parts of the East. 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?