Although temperatures have plummeted in the UK since last weekend, it has been warmer across the Atlantic in southern parts of the US. Dallas Fort Worth airport broke daily maximum records on consecutive days last week, reaching 29C (85F) on 11 January.
The warmth also affected areas further east, with a moist, southerly air mass helping to fuel severe thunderstorms that produced a preliminary count of 60 tornadoes in the south-east on the 12th. The tornadoes resulted in several fatalities in Alabama and Georgia, with one tornado tracking over a path 76 miles long. It has been a very active start to the year across the US, with more than 700 severe thunderstorm and tornado warnings issued already. As of 18 January there had been 135 tornadoes, well above the average of 30 expected up to this point.
Parts of eastern Europe have also been experiencing record warmth this week. Air drawn northwards from the Mediterranean has helped break January temperature records in Moldova, North Macedonia and Romania. Much of southern Romania peaked in the high teens celsius on 18 January, with many stations breaking their monthly record. The capital, Bucharest, reached 20.6C, exceeding the previous record by 3C. The highest temperature was at Turnu Măgurele, close to the Danube and the border with Bulgaria. Here, temperatures reached 22.4C. The warm conditions continued into Thursday but a northward-moving area of low pressure drew colder air into western parts of Romania on Friday.
Colder air had a more significant impact in the Rocky Mountains region earlier this week. A winter storm brought heavy snowfall to Colorado on Tuesday. The storm produced about 23cm (9in) of snow at Denver international airport. Breezy conditions also led to significant drifting as the low pressure system tracked north-east, bringing snowfall to Great Plains states including Nebraska and Iowa. In southern and central Nebraska, accumulation exceeded about 50cm (20in) in places. The area of low pressure continued to track north-east through the week, affecting the midwestern states of Minnesota and Wisconsin on Thursday.