The skyline of the Lujiazui financial zone fades amid heavy smog yesterday.(Wang Rongjiang)
Increasing rainfall is likely to alleviate the air pollution that enveloped Shanghai yesterday, said forecasters.
Drizzle and foggy skies yesterday cut visibility to 1 to 2 kilometers in most of the city.
A combination of weak winds and high humidity created the conditions for the air quality index to reach 202 by 2am, data compiled by the Shanghai Environmental Monitoring Center showed.
The concentration of the main pollutant, PM2.5 particles, reached about 150 micrograms per cubic meter at the same time, six times what is considered safe by the World Health Organization.
The rain and fog also prompted local airports to issue a yellow alert yesterday that delayed flights, reducing air traffic by 20 percent.
The alert system features four colors — blue, yellow, orange and red — to indicate the severity of conditions. Yellow is the second-lowest tier and red is the highest.
The smog and fog are likely to dissipate as the rain intensifies overnight. However, the fog may return after the rain eases.
Next week is expected to be mostly rainy as a result of the combined effect of a subtropical high-pressure system, southwesterly warm moisture and a cold front, the Shanghai Meteorological Bureau said.
According to the weather bureau, three major rainfalls are likely to occur in the coming days: between today and Sunday, Tuesday and Wednesday next week and next Friday.
The current rainy period is forecast to see rainfall of 50 to 70 millimeters in the city, and some parts may see 70 to 100 millimeters.
Thunder and lightning are a possibility.
Today the high will remain at 22 degrees Celsius, but it will rise to 24 degrees tomorrow and 26 on Sunday.
On Monday and Tuesday next week, the high is expected to be between 26 and 27 degrees. Lows will be 19 degrees to 20 degrees.
Shanghai will enter its flood season on Wednesday, with more rain, more high-temperature days and more severe convective weather expected.
