Strong winds and heavy rains are forecast for Chile and Argentina this week, because a strong jet stream is steering low pressure systems across that part of the world.
South-westerly winds from the Pacific will feed in a lot of moisture, resulting in large rainfall totals on top of recent precipitation. Over two days, rainfall totals are likely to reach 30 to 60mm even at low levels across southern Chile, perhaps as far north as the capital, Santiago. The south-westerly winds will also pull in colder air, so significant snowfall is likely over the Andes with 50 to 100cm possible in 36 hours.
Meanwhile, a secondary low pressure system will be cut off over Bolivia, Paraguay and northern Argentina. So while cold south-westerly winds blow over Argentina and Chile – where temperatures will be 10C below average in places – hot winds will raise temperatures by as much as 10C above average farther north. Temperatures will reach over 40C in places.
The dividing line between these hot and cold air masses could bring severe thunderstorms. Over the next couple of days, these will mainly affect Uruguay, north-eastern Argentina and southern Brazil. However, high pressure will gradually edge into southern parts of South America during the rest of the week allowing thunderstorms to edge farther north while colder air will also spread northwards.
Meanwhile, Europe is forecast to experience a very cold end to April and start to May. A large area of high pressure centred between the UK, Iceland and Scandinavia will remain stationary for at least the rest of this week, driving cold air southwards across central and eastern Europe from the Arctic. The development of a low pressure system over north-west Europe will then result in a renewed push of cold air southwards through western Europe by the start of next week.