Snowstorms forecast as La Nina onset nears

Continued snowfall is expected to affect parts of western China over the next few days, potentially having an impact on agriculture, animal husbandry and transportation, the China Meteorological Administration said on Thursday.

From Thursday to Sunday, a plateau trough will bring moderate to heavy snow or sleet to most parts of Qinghai province, the Xizang autonomous region, western Sichuan province, as well as the central and southern parts of Gansu province. Some areas are forecast to experience heavy to blizzard conditions, according to the administration.

China is likely to experience the onset of a La Nina climate pattern in the late autumn, which could bring freezing rain and snow to the north, southwest and central regions this winter, while southern areas may face periods of drought, meteorologists said.

Zhang Daquan, an official with the National Climate Center, said on Wednesday that recent monitoring of the ocean's atmosphere showed much of the equatorial central and eastern Pacific has registered sea surface temperatures below normal, indicating a neutral-to-cool state.

"On that basis, the climate prediction office forecasts a transition to La Nina conditions in the upcoming season," Zhang said.

Historically, during La Nina years in China, the period between December and February has seen a higher probability of below-average temperatures.

"Snow disasters in the north and freezing or icy weather in the south were relatively more common in the earlier decades," Zhang said, adding that the freezing conditions were severe in 2008 and 2018.

However, experts stressed that a La Nina event does not guarantee an "extremely cold winter" and may even result in a warm winter under global warming, Zhang said, citing the winter period spanning 2020 and 2021 as an example.

Furthermore, China's winter climate is not only influenced by tropical sea surface temperature anomalies, but also by factors such as Arctic sea ice, snow cover and mid- to high-latitude atmospheric circulation systems, he added. It's the result of multiple factors working together, requiring a comprehensive assessment that integrates monitoring and forecasting information from the ocean, cryosphere and atmosphere.

According to national standards, a winter is classified as cold or warm only when more than half of the meteorological observation stations nationwide record average winter temperatures that meet the respective criteria. Since the 1990s, China has experienced six cold winters, all occurring before 2012.

"The winter temperature fluctuations in China have become more pronounced, requiring close attention to the potential adverse impacts of sharp cooling and warming events on production and daily life," Zhang said.

The administration expects most northern areas to remain colder than average through Friday, while the south will also remain cool until the end of October, with temperatures in parts of central and eastern China up to 5 C below normal.

Meanwhile, the Yellow River is about to enter the ice jam flood season this year, the Ministry of Water Resources announced recently.

Influenced by both La Nina and global warming, frequent cold-air incursions and extreme weather events this winter are expected to cause sharp temperature fluctuations, complicating ice conditions and posing challenges for flood prevention, the ministry's Yellow River Conservancy Commission said. Preparations for ice flood control along the River are now underway, it added.