The CSI Homepage: Schultz and Schumacher (1999)

SCHULTZ AND SCHUMACHER (1999):
THE USE AND MISUSE OF CSI

Further discussion of the points discussed on this web site can be found in a manuscript written by David Schultz and Philip Schumacher.

Monthly Weather Review published our manuscript "The Use and Misuse of Conditional Symmetric Instability" (Schultz and Schumacher 1999) in the December 1999 issue (pp. 2709-2732); Corrigendum, 128, 1573. You can obtain a copy of this manuscript in one of two ways.

WWW: http://www.nssl.noaa.gov/~schultz/csi/csimwr.html (NOTE: Some fonts may not display properly on your browser.)

American Meteorological Society's Journals On-line: Full Text Article and Corrigenda

We will gladly mail you a reprint. Please email your mailing address.

We would appreciate *greatly* any comments or criticisms, positive, negative, or otherwise, that you might have on this manuscript.

The abstract follows:

A commonly employed explanation for single- and multiple-banded clouds and precipitation in the extratropics is slantwise convection due to the release of moist symmetric instability (MSI), of which one type is conditional symmetric instability (CSI). This article presents a review of CSI with the intent of synthesizing the results from previous observational, theoretical, and modeling studies. This review contends that CSI as a diagnostic tool to assess slantwise convection has been, and continues to be, misused and overused. Drawing parallels to an ingredients-based methodology for forecasting deep, moist convection that requires the simultaneous presence of instability, moisture, and lift, some of the misapplications of CSI can be clarified. Many of these pitfalls have been noted by earlier authors, but are, nevertheless, often understated, misinterpreted, or neglected by later researchers and forecasters. Topics include the evaluation of the potential for slantwise convection, the relationship between frontogenesis and MSI, the coexistence of moist gravitational instability and MSI, the nature of banding associated with slantwise convection, and the diagnosis of slantwise convection using mesoscale numerical models. The review concludes with suggested directions for future observational, theoretical, and diagnostic investigation.

In the December 2000 issue of Monthly Weather Review, Steve Sherwood and we exchanged some additional thoughts on moist instability, which our original article inspired. See below for the complete references.