Apr. 20, 1998 BOULDER--Tornado-bearing thunderstorms raced across central Alabama just after dark on April 8. In their wake, 34 people died, with several other deaths reported in Mississippi and Georgia. Tragic as it was, the high death toll wasn't for lack of official notice. Tornado watches were issued hours before the twisters struck, and 36 warnings from the National Weather Service (NWS) in Birmingham, Alabama, gave residents an average of 13 minutes to seek shelter.
Over the past year, forecasters in Birmingham and in Melbourne, Florida--where twisters killed 42 people in February--have honed their storm-prediction skills with two training modules on CD-ROM: Anticipating Convective Storm Structure and Evolution and A Convective Storm Matrix: Buoyancy/Shear Dependencies. Both modules were prepared by the Cooperative Program for Operational Meteorology, Education and Training (COMET) of the University Corporation for Atmospheric Research (UCAR).
The two modules combine storm theory, observations, and computer models to help users peg storm types in advance when they know a given day's blend of ingredients--in particular, buoyancy (instability fueled by warm, moist surface air) and shear (winds that strengthen and/or veer with height). The modules were prepared with the assistance of Morris Weisman, a meteorologist at the National Center for Atmospheric Research (NCAR). NCAR is operated by UCAR under sponsorship of the National Science Foundation.
"I can't give the modules high enough praise, especially the two convective modules. Both of them are very useful," says Kevin Pence, science and operations officer at the Birmingham NWS office. As the wind shear above Birmingham evolved on April 8 into a classic tornado-producing pattern, "The conceptual models stressed by the modules were certainly being knocked around the office," Pence adds.
Recognizing the Florida weather threat of February 22-23 well ahead of time, the Melbourne forecasters alerted the public to the severe potential 36 hours before the deadly outbreak. "The pattern was a classic severe weather set-up, just like you see in the modules and the textbooks," says Melbourne forecaster Tony Cristaldi. He calls the COMET modules "an excellent extension of the [other] training we receive."
Through residence courses and distance learning, the COMET Program trains meteorologists at weather services, the U.S. armed forces, and universities throughout the world. It is sponsored by the NWS, the Air Force Weather Agency, and the Naval Meteorology and Oceanography Command. The program is in the midst of a multiyear effort to train the nation's forecasters in how to anticipate thunderstorm hazards. The emphasis was first on single storms. Now the focus is broadening to mesoscale convective systems (MCSs), clusters of storms that have their own hazardous qualities.
Since the 1980s, a group of NCAR meteorologists, including Weisman, has forged a body of theory on storm behavior based on the interplay between buoyancy and shear. With Weisman's help, the COMET Program's modules convey the group's work in a three- dimensional, animated format. "Who needs another textbook? We are trying to take a step beyond that to a new level of education," says Weisman. The Convective Storm Matrix includes up to 54 simulated combinations of buoyancy and shear and depicts the kinds of storms one could expect in each situation.
"We've really been pushing the envelope in visualizations," says Wendy Abshire, a COMET meteorologist. COMET visual artists have created more than 10,000 stills and animations for the program's 18 modules to date.
This year COMET is developing a set of new modules that show not just how a single storm grows and dies, but how groups of storms interact with each other and behave as an MCS. Two of the new MCS modules are now available on the World Wide Web, the first time COMET has placed its modules on the Internet. Aimed at the university community, these modules can be accessed by any user whose Web domain name ends in ".edu." To create the MCS modules, Weisman teamed with fellow MCS expert Ron Przybylinski (NWS/St. Louis).
The on-line MCS modules feature a wealth of color imagery: downdrafts and updrafts, vortices forming at the ends of squall lines, supercells evolving into bow echoes, lines evolving into circular masses. The module developers expect serious users to have an upper-division undergraduate or beginning-graduate background. However, site visitors don't need a technical background to admire the beauty of the animations and learn some basic concepts.
Writer: Bob Henson
Note to Editors: Several color illustrations from storm-related COMET modules are available for use in stories covering COMET activities. These images may be obtained electronically from UCAR Communications, 303-497-8607, firstname.lastname@example.org.
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