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.
The Canary Islands had an exceptionally hot end to March, with temperatures widely rising above 34C (93F) on Wednesday and Thursday. The state meteorological agency (AEMET) issued an orange weather warning for temperatures exceeding 37C – the first time this has happened in March. The Tasarte weather station in La Aldea de San Nicolás recorded 37.8C on Wednesday, breaking a 72-year-old March temperature record. The new record stood for just one day, before the same site recorded 38.2C on Thursday.
Antarctica is also experiencing unusually high temperatures. There was a mini heatwave last weekend, with temperatures in the south pole above -40C for more than two days and reaching a high of -33C. Though shy of the record high for March, this was 20 degrees above the seasonal average of -53.7C. Daily highs exceeded -40C once again this weekend. The cause of the unusually high temperatures is thought to be variations in the path of the southern polar jet stream – a rapid air current flowing around the Antarctic region – driving parcels of warm and moist air farther south than normal. Antarctic heatwaves are uncommon but are occurring more frequently as the climate warms. Antarctic sea temperatures are unusually warm this year, with in recent months some of the lowest sea ice levels ever recorded, and this could be another contributing factor to the heatwave. Forecasts suggest parts of Antarctica could continue to have temperatures 20C or more above average into late April.