Hanoi: Hail again

Around 22:30 last night (February 14), hailstones appeared in Cau Giay, Thanh Xuan and Tu Liem districts within about 15 minutes. However, very few people are aware of hail because shortly before a shower of rain and size of stones are not large.

Commenting on this hail, Deputy Director of the Central Center for Hydrometeorology Nguyen Lan Chau said: The reason is that the North has a round of cold air intensified. Because hail occurs locally in the area, there has not been any observation station in Hanoi this morning, at Lang station, only the last 2 mm of rainfall was measured. However, this is an unusual phenomenon of the weather this year, because hail is very rare at this time (usually only occurs during the season from hot to cold October-November, or vice versa 4-5).

Hail falls full of houses in Trung Hoa - Nhan Chinh area on November 20, 2006.(Photo HA)

According to scientists, this is a very unusual weather event and this phenomenon is likely to happen in the future. Dr. Nguyen Duy Chinh, Deputy Director of Institute of Meteorology, Hydrology and Environment, said: Hail is very unlikely to appear in the North in the rest of 2006.

However, in March and April and even in February of 2007, hailstorms can occur in the northern mountains. In addition, in the coming time, it is necessary to watch for hail phenomena which may appear in coastal areas and adjacent to the mountainous areas of the Central region.

Dr. Bui Minh Tang, Director of the Center for Central Hydrometeorological Forecasting commented: This is the phenomenon of small-scale weather, very dangerous, very difficult to forecast but occurs on a large scale in many provinces. , city. According to monitoring data in the past 50 years, there are only 5-6 hail events in Hanoi, hail in Hanoi from November to February, except for hail on the day. November 20, 2006.

In our country, dangerous weather phenomena such as above and harmful are not uncommon, but never thunderstorms, tornadoes and hail occur on a large scale and cause great harm to the present. In addition, hail occurs often in the second half of winter, the transition period from the cold season to the hot season rather than from the hot season to the cold season, not to appear in early spring.

Scientists at the Institute of Meteorology, Hydrology and Environment said : The cause of the unusual weather is due to a very synchronous combination of 3 phenomena: hot and sunny hot cushion surface. prolonged heat, converging high-flow currents and enhanced cold air in the lower atmosphere.

These three phenomena appear at the same time, causing the atmosphere to become unstable, facilitating deep convection movements producing thunderstorms, tornadoes and hail. Besides, although it is not possible to explain clearly the physical mechanism of the relationship between El Nino and prolonged hot weather in recent years in most areas of the North, but the scientists Learning affirms: this is one of the consequences of the El Nino phenomenon.

In terms of climate, it can be said that the El Nino phenomenon plays an important role in the appearance of hail in the North in the past time, due to strong convection appearing when cold air overflows to the chi coordinated by hot air mass.

LLB