In recent days, the weather in all three regions has been mostly hot. However, the weather in the North is about to change direction.
According to the National Center for Hydro-Meteorological Forecasting, today, April 23, the low pressure trough with an axis at about 22 - 25 degrees north latitude was weakly compressed, pushing the epidemic south.
In the evening and night of April 23, the mountainous and midland areas of the North will have scattered showers and thunderstorms, locally heavy rain with rainfall of 15 - 30mm, some places over 50mm.
The meteorological agency warns that thunderstorms may cause tornadoes, lightning, hail and strong gusts of wind. Localized heavy rains are likely to cause flash floods on small rivers and streams, landslides on steep slopes and flooding in low-lying areas.
In fact, in the past month, there have been many thunderstorms and hail in the provinces of Son La, Lai Chau, Thanh Hoa, Nghe An.
According to Mr. Nguyen Huu Thanh - Deputy Head of Weather Forecast Department, National Center for Hydro-Meteorological Forecasting, hail and thunderstorms often appear due to weather patterns that cause strong disturbances in the atmosphere. Some key situations that can cause this phenomenon are when cold air flows down and the overwhelming hot and humid air creates strong contact, leading to thunderstorms, lightning and hail.
Another situation is high-altitude wind convergence (such as at 5,000m). The air was suddenly pushed up, causing thunderstorms to develop strongly. If the temperature in the upper atmosphere is cold enough, the water particles freeze and fall down, creating hail.
According to statistics, weather patterns still appear and operate accordingly according to the time of year. In addition to the weather patterns appearing in a certain area, there may also be hail in combination with the weather conditions of each locality.
"Ice in the North and Central regions often appears during the transitional months between summer and winter (from September to November) and from late winter to summer (from late February to May). At this time, there will be a dispute between cold air and hot air" - Mr. Thanh said.
According to the representative of the meteorological agency, the forecast of thunderstorms, lightning and hail in this year as well as in the coming years tends to appear more than average.
Rocks and ice are a dangerous weather phenomenon that can cause property damage and cause unsafety to people. Signs that can recognize hail are when there are unusual changes in the weather.
"Easy to recognize signs such as the weather is sunny but suddenly turn dark clouds, strong winds, and strong thunderstorms. Rapid temperature drops are also a sign. Before the hail, the air usually cools down" - Mr. Thanh advised.
