Wed, Jul 14, 2004 - Page 8 News List

Importance of forecasting revealed

By Liu Chung-ming 柳中明 and Young Chea-yuan楊之遠

On the afternoon of June 30, Tropical Storm Mindulle began to slowly move northward from Luzon Island in the Philippines. The high pressure zone over the Pacific, which had directed the tropical storm in a westerly direction, weakened, causing the storm to move forward slowly, constantly changing direction, giving weather forecasters a major headache. Later, on July 1 and July 2, the storm moved northward along the east coast of Taiwan, and on the morning of July 2 the center of the storm moved from the Tamsui River out to sea. Over the two following days, however, strong southwesterly winds caused heavy rains and flooding in the center and south of the country.

Before the storm, the Taichung area experienced record-high temperatures and afterward was drenched by continuous rains. These unexpected events are deeply disturbing. On the one hand, although the Central Weather Bureau kept issuing warnings, these warnings were obviously indecisive and unclear, and the many estimated possible changes to the situation confused the general public. On the other hand, most people thought that Mindulle was merely a tropical storm that was moving along the east coast, and they did not expect that it would have any significant effect after leaving Taiwan. Given the lack of anticipation, it is particularly difficult to accept the disaster for the central and southern regions.

The winds brought by Mindulle resulted in record temperatures of 37.4?C in Hsinchu and 39.9?C in Taichung. The slow progress also resulted in rarely-seen tornados along the coastal regions of Yunlin and Chiayi counties.

In addition, the storm coincided with the Joint University Entrance Exam. Should the exam period have been extended because of this? Since the issue involves tens of thousands of students and their parents, the authorities in charge should give the issue thorough consideration. Fortunately, although students in some regions were affected by the bad weather, none of them died or was injured. Judging from the disaster resulting from Tropical Storm Mindulle and given the unreliable nature of weather forecasts, future decisions should integrate concerns over possible climatic changes. This is the only way to avoid the difficult situation that arises when reality does not coincide with forecasts.

This time around, a cautious Central Weather Bureau kept explaining how difficult it is to predict the weather accurately, and made public comparisons with the forecasting methods used in the US and Japan. Its cautious treatment of the situation is in fact a reflection of the pressure experienced by weather forecasting personnel.

Two factors may have contributed to the difficulty of forecasting the development of Tropical Storm Mindulle.

First, this storm approached the country from the southeast. If there had been a small change in direction, it could have moved toward the west coast, directly hitting Hengchun, or moved along the east coast. Each route would have resulted in differences in regional impact.

Second, the abnormal weakening of high pressure zones over the Pacific is a result of changes in global atmospheric circulation, and it therefore also affects the movement of typhoons and tropical storms in the vicinity of Taiwan. Forecasters in other countries used different models to predict Mindulle's course, which suggests that, given the abnormal climatic conditions, there is still much room for improvement in typhoon forecasting.

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