Typhoons, scorching hot weather and other disastrous or extreme weather will be more common in the city this year than last, the Shanghai Meteorological Bureau forecast yesterday.

 

Average temperatures in the city for the year will be slightly higher than the average of 16.2 degrees Celsius recorded over the past 10 years, the bureau said. The number of days with highs topping 35 degrees will also be higher than normal, according to the forecast.

 

Precipitation levels will be close to the average over the last decade of 1,190.8 millimeters, including the June to September flood period, which will receive a normal amount of rain - close to the 642.2 millimeters average of the past several years.

 

The bureau will release a specific forecast for the year in May.

 

Last year was relatively free of disastrous weather in the city, with Shanghai receiving a long, hot summer and a short, wet fall, the bureau said yesterday as it released a list of the 10 main weather phenomenon in the city during 2006.

 

High temperatures

 

The average temperature in the city last year was 18.3 degrees, 2.1 degrees higher than normal. That was the highest average temperature recorded in the city since records were first kept in 1873.

 

Longest summer

 

Shanghai had its longest summer in 51 years last year, running from May 20 to October 23. The summer saw 27 days with highs topping 35 degrees, 18 days more than the average over the past 10 years.

 

The average temperature during July and August was 30.1 degrees, 2.3 degrees higher than the average for recent years. That was the highest average recorded since 1873 for the same period.

 

Late autumn

 

Autumn didn't arrive in the city until October 23, its latest entrance in 134 years. The season arrives after five consecutive days with average temperatures below 22 degrees. The average temperature in October was 22.3 degrees, the highest ever recorded in the city.

 

The warm weather was great for flower lovers in the city, as osmanthus, chrysanthemums and orchids went into blossom at the same time.

 

Earliest typhoon

 

Typhoon Chanchu affected the city from May 17 to 19, bringing heavy rains and strong winds. It was the earliest point of the year for a tropical cyclone to hit the city in history.

 

Cold front

 

A strong cold front entered the city on March 12, dropping temperatures by 10.3 degrees within two days. The strongest cold front of the year damaged some crops.

 

Dry plum rain season

 

The city had a relatively dry and hot plum rain season, which lasted from June 13 to July 12. The city received only 183.8 millimeters of rain during the period, far less than the average 244.4 millimeters in recent year. During the plum rain season, the city suffered through seven days with highs topping 35 degrees, second only to 1917 for the same period, which had nine such days.

 

Lightning strike

 

Lightning strikes were the most serious weather phenomenon to hit the city last year. Five people were killed and one was injured by lightning. Strikes also destroyed the communication equipment at a satellite earth station as well as 620 household electrical appliances.

 

November rain

 

The city had much more rain in the past fall than average for the same period. From November 16 to 30 the city received 136.6 millimeters, almost four times the average over recent years. The rain damaged many crops, especially rice and wheat.

 

Haze and fog

 

The city had six hazy days last year, about two or three more than normal. It also had 14 foggy days, which affected the city's air quality, visibility, and traffic.

 

In the city, nearly 100 flights delayed because of haze or fog last year, and highway and elevated roads were closed for 13 times.

 

Haze and fog were mainly caused by warm weather and pollution from vehicles and factories.

 

Fog: The term is used when visibility is one kilometer or less, the relative humidity is 95 percent or more and atmospheric obscurity is caused by suspended microscopic water droplets or wet hygroscopic particles.

 

Haze: The term is used, whatever the horizontal visibility, when the relative humidity is less than 95 percent and visibility is reduced by very small, dry, solid particles suspended in the atmosphere.

 

Solar flare

 

Although the solar flare eruption on December 13 and 14 did not have much effect on the Yangtze River Delta, the electron density of the area soared to around 17 TEC units - a measure of electors per square meter. The eruption, which was the most serious since 1957 in low solar activity years, unleashed enough radiation to disrupt radio communications in other parts of the country, including the provinces of Guangdong and Hainan, as well as the municipality of Chongqing.

 

Solar flares: A solar flare is a tremendous explosion on the sun that happens when energy stored in "twisted" magnetic fields, usually above sunspots, is suddenly released.

 

In a matter of just a few minutes they heat material to many millions of degrees and produce a burst of radiation across the electromagnetic spectrum, including from radio waves to x-rays and gamma rays.

 

(Shanghai Daily January 12, 2007)