Thursday, March 25, 2010

CAPE is the Question


RUC 0-3km MLCAPE, effective at 5 p.m.

CAPE stands for convective available potential energy. Essentially, CAPE is a measure of the instability in the atmosphere which is one of the main ingredients for severe weather. Warm, moist air near the surface, combined with cooler, dry air aloft causes "instability". This instability helps provide lift and moisture for convection, or thunderstorm development. Without convection, thunderstorms would not develop. Tornado development usually requires a significant amount of instability in order to develop supercells or other forms of convection. Many other factors, though, are necessary for tornado development. Wind shear (changes in direction and speed of winds with height) is critical, among others. I have noticed in recent years that tornadoes have formed many times in situations where instability values were not impressive but shear and other factors were strong. Case in point: the Huntsville tornado of January 21, 1010.


Let's see if that happens today.

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2 comments:

Sharp said...

The NWS has wind shear records going back a thousand years? 1010? Wow. Those Native Americans had game!

Just messing with you.

Anonymous said...

Hahaha... oops!