In the afternoon of June 8, many northern mountainous provinces began to experience thunderstorms.
In Lang Son, dark clouds came to the central urban area from the early afternoon, then rain poured down quickly, causing visibility on some streets to decrease.
This widespread rain is predicted to be caused by cold air mass from mainland China moving southward, compressing a low pressure trough with an axis of about 24-27 degrees North latitude, connected to the hot low pressure area to the west moving down to the North. This configuration combines with the wind convergence zone at high altitude, creating a bad weather combination.
In Son La, the Provincial Hydrometeorological Station forecasts that from the evening of June 8 to the end of the night of June 9, the whole province will have heavy to very heavy rain, with scattered thunderstorms.
Common rainfall of 70-160 mm, in some places over 250 mm; risk of localized heavy rain intensity over 100 mm in 3 hours.
The areas of Quynh Nhai, To Hieu, Muong La, Mai Son, Song Ma, Bac Yen, Sop Cop and Thuan Chau are forecast to receive 80-160 mm of rain. Yen Chau, Phu Yen, Moc Chau, Van Ho rain 70-120 mm.
Also during this period, cold air affected the southeastern area of Son La from early morning on June 9, including Bac Yen, Phu Yen, Yen Chau, Moc Chau, Van Ho, then weakly affected other places.
From June 9, Son La will turn cool, northeast wind level 2-3; the lowest common temperature is 20-22 degrees C, high mountainous areas 19-21 degrees C.
In Lao Cai, from the evening of June 8 to the morning of June 10, the whole province had rain, moderate rain and thunderstorms; many places had heavy rain, some places had very heavy rain accompanied by strong thunderstorms. Rainfall for the whole period was commonly 50-100 mm, with some places over 200 mm.
Heavy rain concentrated in the night of June 8 and day of June 9 in Nghia Lo ward, Sa Pa; Luc Yen, Tran Yen, Mau A, Van Chan, Tram Tau, Mu Cang Chai, Bat Xat, Bac Ha, Muong Khuong, Van Ban, Si Ma Cai communes and surrounding areas.
After that, the rainy area may shift to other communes and wards.
The meteorological agency warns of a very high risk of flash floods and landslides in some communes and wards in mountainous areas, especially areas with steep terrain, riverbanks, streams, taluys and places where landslides have occurred.
In Cao Bang, the Provincial Hydrometeorological Station said that on June 9, the areas in the province will be cloudy at night and in the morning, with showers, in some places moderate rain, heavy rain and thunderstorms; intermittent sunny days.
From June 10 to 12, the weather will be cloudy at night and in the morning, with light showers and thunderstorms in some places; sunny during the day. The lowest temperature is commonly 23-25 degrees C, the highest is 30-32 degrees C.
Local authorities are advised to review high-risk areas, be ready to relocate people and property to safe places; arrange forces, materials, and vehicles on the spot at key points. People should limit going through spillways, streams, taluy areas and roads at risk of landslides during heavy rain.
