Early rainy season heightens flood risk in North China

Northern China is entering its most critical flood-control period, with meteorologists warning that an early rainy season and increasingly volatile weather patterns could heighten the risk of severe flooding in the weeks ahead.

The rainy season in North China officially began on July 10, eight days earlier than the long-term average, according to the National Climate Center. The early onset follows months of exceptionally heavy rainfall that has already left much of the region saturated before the traditional peak flood season.

From April 1 to July 12, average precipitation across northern China reached 228.6 millimeters, 23.1 percent above the long-term average and the highest for the same period in the past decade, the center said. In North China, average rainfall totaled 288.4 mm, 62.5 percent above normal and the highest on record for the same period.

Hebei province and Tianjin both recorded their wettest such period since meteorological records began in 1961.

"The rainy season this year has arrived both early and with remarkable intensity," said Chen Lijuan, chief forecaster at the center.

She said an active Northeast China cold vortex — a persistent upper-level weather system that often triggers prolonged rainfall — has contributed to unusually heavy precipitation across northeastern and northern China since June.

The rainy season in Northeast China began on June 4, nine days earlier than average. Since June 1, rainfall has been well above normal across most of the region and North China.

Large parts of Hebei, for example, have received more than 50 percent above-average rainfall, while some eastern areas of the province recorded as much as 12 times their normal precipitation. Much of Liaoning province has also received more than twice its normal rainfall.

The unusually wet start has heightened concerns ahead of the main flood season, which runs roughly from July 16 to Aug 15 and is traditionally the most challenging period for flood control. About one-third of North China's annual precipitation typically falls during those four weeks.

Forecasters said the unusually wet conditions could leave many river basins and mountainous areas more vulnerable to flooding if additional rounds of intense rainfall develop.

The center forecasts above-normal precipitation across most of northern China during the upcoming flood-control period, with rainfall expected to exceed seasonal averages by 20 to 50 percent in parts of Beijing, Tianjin, Hebei, Liaoning, Heilongjiang and the Inner Mongolia autonomous region.

Meteorologists warned that some areas could experience extreme downpours capable of triggering floods, flash floods and landslides.

"The background of climate warming is making weather more extreme and more complex, while climate patterns themselves are changing," said Chen Tao, chief forecaster at the China Meteorological Administration.

"As a result, monitoring and forecasting have become more difficult. High-impact extreme weather events are occurring more frequently, often exceeding historical experience and traditional design standards," he said.

Chen said the interaction between global warming and large-scale climate patterns such as El Nino means weather disasters are increasingly occurring simultaneously across multiple regions rather than as isolated events.

In response, flood prevention efforts will focus on strengthening weather monitoring and early warning systems in northern river basins while improving coordination among meteorological agencies, the administration said.

Authorities have been urged to intensify monitoring during high-risk periods, such as overnight heavy rainfall, and strengthen emergency coordination for flash floods, geological disasters and flooding along small and medium-sized rivers.

Meteorological services will also work with other departments to provide weather support for transportation, the summer grain harvest and energy supplies.

Residents are advised to pay close attention to weather alerts and avoid entering mountainous areas and river valleys during and immediately after heavy rain, as rapidly developing flash floods are among the deadliest hazards during North China's rainy season.