Brazil braces for widespread cold snap, frost, and snow expected across multiple regions
Image credit: ECMWF/TropicalTidbits
A very cold polar air mass is forecasted to cause a significant drop in temperatures across multiple regions of Brazil by the end of this week. The South, Southeast, Central-West, and even parts of the North will experience this temperature decrease, with the possibility of frost in several states and potential snowfall or freezing rain in the higher-altitude areas of the South Region.
The cold air mass is expected to affect a large portion of the Center-South region of Brazil, leading to temperature anomalies at the 850 hPa pressure level, which corresponds to an altitude of 1 500 m (4 921 feet), according to data from the European Centre for Medium-Range Weather Forecasts (ECMWF).
These anomalies indicate a significant deviation from the mean temperatures typically observed. The entry of this cold air is already in progress in parts of the South and Central-West regions, with its influence expected to expand and continue through August 10, 2024.
Although this cold air mass is not as intense as those observed at the end of June and in early July, it will cover a broader area of Brazilian territory. The temperatures in the central parts of the country are expected to drop lower than during previous cold events.
The cold air mass, advancing with a continental trajectory through the interior of the continent, is affecting areas that recently experienced intense heat, such as Mato Grosso in the central west and parts of the North of Brazil.
A low-pressure area on the coast of Rio Grande do Sul is facilitating the advancement of this cold air further into the continent, reaching multiple states. The presence of low pressure is also expected to bring drier air and cold conditions to the Central-West and Southeast regions, causing both low minimum temperatures and the likelihood of frost.
The coldest mornings are expected to occur over the weekend. Single-digit temperatures are anticipated in the capitals of the South, in Campo Grande, and São Paulo. The coldest morning in Campo Grande is predicted for August 10, with temperatures possibly dropping to 7 °C (44.6 °F).
In São Paulo, morning temperatures could range between 3 °C and 5 °C (37.4 – 41 °F) at Mirante de Santana, with even lower temperatures expected in the southern parts of the city on August 11. In Porto Alegre, morning temperatures could be as low as 6 °C or 7 °C (42.8 – 44.6 °F) at Jardim Botânico on August 11.
Negative temperatures are expected in the highest-altitude areas of southern Brazil, particularly in Campos de Cima da Serra in Rio Grande do Sul, Planalto de Palmas in Paraná, and Planalto Sul Catarinense. The Mantiqueira region, spanning São Paulo, southern Minas Gerais, and Rio de Janeiro, is also likely to experience below-zero temperatures.
Most municipalities in Rio Grande do Sul and Santa Catarina are projected to have minimum temperatures around or below 5 °C (41 °F).
This cold air mass is expected to bring the most widespread frost event of the year to South-Central Brazil. Frost is anticipated in various areas of southern Brazil, as well as in parts of Mato Grosso do Sul and São Paulo. Isolated frost may also form in the higher-altitude areas of Rio de Janeiro and southern Minas Gerais.
Localized and weak frost could also occur near southern Goiás and the Triângulo Mineiro region.
Predicting snow remains challenging due to the rarity of the phenomenon. Recent model simulations have shown a decrease in the likelihood of snowfall in southern Brazil, although some models, such as the WRF, still indicate a possibility.
The atmosphere is expected to be cold enough for snow, but limited precipitation may reduce the chances. A cold low-pressure system will move through eastern Rio Grande do Sul between August 9 and early August 10, bringing clouds, cold weather, and possibly light precipitation.
Snow cannot be ruled out in the higher-altitude areas of Northeast Rio Grande do Sul, particularly in Campos de Cima da Serra, and in the Southern Planalto Catarinense, mainly at altitudes above 1 000 m (3 281 feet), on August 9 and early August 10. Freezing drizzle or rain may also occur at lower altitudes in these regions.
References:
1 POLAR AIR ENTERS BRAZIL: SEE TEMPERATURE, FROST AND SNOW PROJECTIONS – METSUL – August 8, 2024
I am an Assistant Editor and Severe Weather & Science Journalist at The Watchers, specializing in real-time severe weather coverage, geophysical event reporting, and research-driven scientific analysis. You can reach me at rishav(at)watchers(.)news.
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