The North welcomes cold air in early May, hail and thunderstorms appear more often

Why does white hail appear in Son La?

Recently, the North has continuously experienced extreme weather such as thunderstorms, tornadoes, and hail. Notably, the hailstorm on the afternoon of April 24 in Son La and Hoa Binh caused a lot of damage to people’s property and crops.

Explaining this, Mr. Nguyen Van Huong, Head of Weather Forecasting Department, National Center for Hydrometeorological Forecasting, said that the North During the changing seasons, there are frequent conflicts between air masses with different characteristics, the atmosphere becomes more unstable, so thunderstorms also occur more often than at other times of the year.

In some cases where convection develops strongly, in addition to causing heavy rain, it may be accompanied by hail and strong winds.

“The case of the thunderstorm on April 24 in the area between Hoa Binh and Son La is a typical example, the cause is the influence of the southern edge of a weak cold air mass, combined with the activity of a wind convergence area above An altitude of 1,500 m is created by the western edge of the subtropical high pressure tongue (sea air mass encroaching from the east), plus the southwest wind moving from Upper Laos, converging in the area along the longitude. route 105. Therefore, the areas of Son La, Hoa Binh, Thanh Hoa, and Nghe An have strong showers and thunderstorms,” ​​Mr. Huong explained.

According to Mr. Huong, Satellite data estimates that the peak temperature of convective clouds during the afternoon thunderstorm on April 24 was at minus 81.2 degrees Celsius. This is a sign that the convective cloud tower is developing very violently. The height of the cloud mass can be over 10 km. Outbursts of such cloud towers often appear during the transition period and cause strong thunderstorms or hail. At that time, the cloud area had developed strongly and moved slowly, causing concentrated hail in the area adjacent to Son La and Hoa Binh.

The North welcomes weak cold air in early May

Head of Weather Forecasting Department forecasts, After April 30, in the first 1-2 days of May, there will be a weak cold air mass moving down from mainland China. Therefore, in the North, from May 1 to 2, showers and thunderstorms are likely to appear again, while in the South, southwest winds also tend to appear, causing thunderstorms.

“In the North and the South, we need to be wary of thunderstorms, tornadoes, lightning, hail and strong winds. We forecast that from now until June (with the focus on May) will be a period of change. changing the weather from the cold season to the hot season, the dry season to the rainy season in the North, so strong thunderstorms with tornadoes, lightning, and hail are most likely to appear during the year, especially in mountainous areas, due to the impact terrain can create strongly developed convection clouds, resulting in thunderstorms with tornadoes, lightning, hail and strong winds. During thunderstorms, tornadoes, lightning and hail in the North, Thanh Hoa, Nghe An and Ha Tinh areas often appear in the afternoon, evening and night,” Mr. Huong noted.