Flood

El Nino to have crucial impact on the fall: CWB

By Shelley Shan  /  Staff reporter

The nation could still face another typhoon this fall due to El Nino, which is poised to be the strongest one since 1997, the Central Weather Bureau said yesterday.

The bureau yesterday gave its long-range forecast for this month to November.

Weather Forecast Center Director Cheng Ming-dean (鄭明典) said the strength of this year’s El Nino is almost comparable to the level of the super El Nino that lasted from 1997 to 1998, and it still has room to gain in strength.

El Nino refers to atmospheric changes caused by the higher ocean temperature in the equatorial region between the Central and East Pacific Ocean.

El Nino is forecast to continue affecting the nation’s weather this fall and reach its peak between the end of this year and the beginning of next year, Cheng said.

The bureau’s data indicate that an average of 1.2 typhoons are likely to affect Taiwan after this month, but the likelihood that one would directly hit the nation is very low, he said.

“We forecast approximately one typhoon could become a direct threat to Taiwan in the fall,” he said. “Because of a strong El Nino effect, the high air pressure becomes weaker, which makes it more likely for typhoons to move north before reaching Taiwan.”

El Nino often leads to less rainfall than normal in the South China Sea, the Philippines and the Indonesian archipelago, which means Taiwan is likely to see less rainfall in the autumn than normal, he said.

“The nation is sandwiched between a dry zone and a wet zone. The rainfall could be less or more than normal depending on which one of the systems prevails. We forecast that it is more possible that the nation would be influenced by the weather system in the dry zone,” he said, adding that temperatures are also likely to be warmer.

Taipei experienced a relatively cooler August this year, with only nine days where temperatures exceeded 35?C, he said.

There were 20 days in August last year where the temperature reached 35?C or above.

Keelung saw 676mm of rain last month, a new record since the bureau’s observation station in the city was established in 1946, while Penghu had a total of 794mm, its second-highest since 1898.

Aside from the rain brought by Typhoon Soudelor, other rainfall contributed to last month’s cooler weather, including a low air pressure system formed through the convergence of the southwest and north winds, southwest jet stream and stationery front, Cheng said.

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