News from Our Chapters Houston

At the 21 May meeting, awards were presented to two students for outstanding meteorological projects from the 1991 Houston Regional Science Fair. Both students were presented with certificates and a year's subscription XoWeatherwise. The senior-level award winner was Steven Crawford, who had presented a project entitled "Dynamics of Common Thunderstorm Types." Jeff Thorner, the junior-level award recipient presented a project which he titled "Home Weather Forecasting." The ninth-grade winner, David Boggs, was unable to receive his award in person but is to be congratulated for his project called "The Formation of A Tornado."

The guest speaker at the May meeting was Robert Spellicy, who is senior program manager at Radian Corporation. Spellicy discussed some opf the remote sensing systems for detection of pollutants in the air. The advantage of remote sensing is not only the ability to look at many compounds simultaneously, but also the ability to do so over very long paths up to kilome-ters in length.

Kansas City Over 100 members and guests attended the meet-

ing held at the Kansas City Royals Stadium Club on the evening of 29 May 1991. Ted Fujita, professor emeritus of the University of Chicago, spoke on the topic, "What I learned from Three Significant Tornado Episodes in 1990."

The three tornado episodes that Fujita spoke about were the Hesston, Kansas, episode of 13 March 1990; the Plainfield, Illinois, episode of 28 August 1991; and the Tokyo, Japan, episode of 11 December 1990.

The Hesston, Kansas, tornado was actually two tornadoes. One tornado dissipated as another formed. The intensity of the tornadoes, an F5 on the Fujita Tornado Scale, was determined by the circular dam-age patterns caused by the suction vortexes within the tornado. These types of circular patterns were first seen in the Palm Sunday 1965 tornado outbreak. A microburst of wind effected the path of the tornado. What made the Heston tornado particularly interesting was that as one tornado was dissipating another new tornado formed and affected the speed and direction of the older tornado. During the time both tornadoes were in existence, they rotated about a common center. This case documents for the first time that the Fujiwara Effect can be applied to tornadoes. Fujiwara, director of the Japan Weather Service, noted that two

typhoons located relatively close to each other will rotate around each other. This finding is extremely important to the tornado warning program. It can never be assumed a tornado will move in a straight line if a second tornado forms nearby.

Fujita showed examples where the Fujiwara Effect applied to two mesocyclones in Tennessee and Geor-gia on 3 and 4 April 1974.

In the 1970s, most tornadoes near Chicago oc-curred northwest of the city. In the 1980s, the focus of tornadic activity shifted southwest of the city proper. I n 1990, this trend with the Plainfield tornado occurring southwest of Chicago continued.

The Plainfield tornado was characterized by twin peaks of very cold air aloft, shooting through and above the anvil of the storm as shown from a polar-orbiting satellite. This same double structure was confirmed by weather radar depiction taken from a commercial aircraft. A damaging downburst of wind occurred well ahead of the formation of the tornado. Most of the damage from the tornado was attributed by Fujita to the suction vortices within the tornado. Suction vortices that form and dissipate a number of times during the life of the storm explain the skipping pattern of damage along the tornado's path.

The Tokyo-area tornadoes occurred after dark on 11 December 1990. Over 1800 homes were de-stroyed. Four hook echoes were seen on the radar display that night at the same time. The tornadoes were classified as F3's on the Fujita Tornado Scale. The largest tornado path width was 300 ft. Downbursts of wind in this episode affected the tornado's path. Due to the rarity of tornadoes with such strength in Japan, the Japanese initially determined erroneous tornado paths. This again was due to the damage pattern from the internal suction vortices in the torna-does. Fujita stated that an international team of ex-perts is required to assess storm damage when an episode of such magnitude occurs in a country.

Fujita concluded his talk by stating that the amateur video photographer will bring an abundance of added information into the analyses of future tornadic epi-sodes. But this video information can only compliment and not replace areal damage assessment of a tor-nadic episode.

The meeting ended with Fujita providing the chap-ter with a few slides of the prestigious award of merit that he received from the emperor of Japan.

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1424 Vol. 72, No. 9, September 1991

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EXTRATROPICAL

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