Thundertorm and heavy rains hit Vietnam from night of May 17 to morning of May 18.

Colored IR image by FY-4B shows the convection reached its peak at 11:00 (UTC) on May 17 with cloud top colder than -80°C.

Colored IR image by FY-4B from May 18 to 21 show strong convections concentrating at night.

Colored IR image by FY-4B on May 23 shows new strong convections developing rapidly.