Weather tracker: 385 tornadoes in US already this year

Number likely to increase this week as upper-level low travels east across country and low pressure moves north-east

Tornadoes affected several US states on Friday - particularly Iowa, Illinois, Arkansas and Tennessee - causing significant damage and a number of fatalities. It has been a fairly active year for tornadoes so far, with a preliminary total of 385 across the US as of 2 April, and that is likely to increase this week. An upper-level low will move slowly east across the US, while at lower levels an area of low pressure moves north-east from the central Rockies towards the Great Lakes.

Warm, moist air is expected to be drawn northward through much of the eastern half of the US. Severe thunderstorms are anticipated, with parts of the south and lower midwest likely to be affected again. The strongest storms are expected on Tuesday, when supercells - the rotating thunderstorms responsible for many tornadoes - are likely. The National Weather Service's Storm Prediction Center is warning of the potential for strong tornadoes and damaging straight-line winds.