The warning applies to almost all of Västerbotten as well as parts of Jämtland, Norrbotten, and Västernorrland. The storm is expected to move in during late afternoon and evening. The warning is in effect from 16:00 until 01:00 on Friday morning.
There is a risk of thunderstorms that could become very severe with many lightning strikes, SMHI says in the warning.
– There is also a risk of large hail and very strong gusts of wind, SMHI writes. Flooding can occur in basements, underpasses, and on roads. Residents are urged to clear gutters, storm drains, and check that basements are sealed. Drivers are advised to watch out for aquaplaning.
Lightning strikes can cause disruptions to electricity and telecommunications networks as well as train and air traffic. There is also an increased risk of fires.
– It can be dangerous to be outdoors when there is a lot of lightning. Stay away from tall objects, such as trees and poles, and avoid swimming, SMHI writes.
The weather institute points out that there is great uncertainty about where and when the thunderstorms will form and that some areas within the warning zone may not be affected.
SMHI has also issued a yellow warning for strong winds in the Bothnian Bay, valid during Friday afternoon and into the evening.