Extended Abstract (512K)P9.7
A Case Study of the Fort Worth and Arlington Tornadic Supercells of 28 March 2000
Jason K. Jordan, Texas Tech University and NOAA/NWSFO, Lubbock, TX; and A. R. Moller and M. Vescio
On 28 March 2000, a series of tornadic and non-tornadic supercell thunderstorms affected North Texas. Two tornadoes struck populated areas of Tarrant County, resulting in 2 deaths, 80 injuries, and damage of almost a half billion dollars. The extensive damage came from tornadoes that were relatively small, and limited to producing damage mainly in the F2, and occasionally lower F3 categories.
The paper deals with the meteorological and the sociological challenges that severe storms and tornadoes present for large population centers. We concentrate on the forecast, warning decision, warning dissemination, and public response aspects of the Integrated Warning System, as applied to the March 28 event.
The forecasting process was difficult, in that synoptic and subsynoptic scale conditions (mainly provided by upper air analysis and numerical model solutions) initially appeared more favorable for tornadoes north of the Dallas-Fort Worth area. Nevertheless, National Weather Service forecasters used mesoscale analysis of observational data (including profilers and hourly analysis of various surface data fields) to conclude by late afternoon that tornadoes could become a threat further south, including the DFW area.
The warning decision process also was difficult, in that more classic Doppler radar indicators of tornadoes (namely a deep mesocyclone with a strengthening low level circulation and/or a Tornadic Vortex Signature) were absent. Other Doppler radar factors were used in determining that a tornado warning was warranted for the Fort Worth area. Numerous other thunderstorms, a number of them supercellular, necessitated a strategy of sectoring out warning areas within the county area of responsibility to three different forecasters, spreading office resources. Finally, the first tornado developed in a neighborhood that was without resident Amateur Radio storm spotters; thus lack of real-time spotter reports further hampered the tornado warning decision process.
The tornado warnings were dessiminated via the news media, sirens, and NOAA Weather Radio, as well as other more informal methods of warning delivery, including, widespread cell phone usage that eventually caused an overload to the system. We show that each of these dissimination routes were valuable in delivering a consistent warning message to an attentive public. Most affected residents followed safety procedures adequately, although exceptions included both of the fatalities and some of the more severely injured.
Supplementary URL: http://www.atmo.ttu.edu/jjordan/research/ftwtor/
Poster Session 9, Warning, Dissemination and Verification
Wednesday, 14 August 2002, 3:00 PM-4:30 PM
Previous paper