National Weather Service United States Department of Commerce

Tropical Rainfall Continues from the Remnants of Imelda

Intense tropical rainfall continues in portions of Southeast Texas and Southwest Louisiana from the remnants of Imelda. These additional rains will only compound ongoing issues with flooding. The heavy rain focus will gradually shift to the ArkLaTex region on Friday. Also on Friday, a cold front arriving into the Upper Midwest will likely produce severe thunderstorms and locally heavy rainfall. 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?