Several monthly records, even some records from April, could be broken in the coming days.
A powerful “heat dome” responsible for the heatwave
This remarkable weather situation is explained by the presence of a heat dome over the western United States. This phenomenon corresponds to an area of very persistent high pressure that acts as a lid in the atmosphere.
The warm air then becomes trapped near the ground and gradually warms up day by day due to the sunlight. This configuration also promotes very stable and dry weather, which further increases the rise in temperatures.
The heat dome is expected to mainly affect California, Arizona, Nevada, and New Mexico, with a possible extension towards Utah, Colorado, and some regions of Oregon.
Temperatures worthy of summer in the middle of March
In the most exposed regions, temperatures could rise 20 to 30°F (10 to 15°C) above normal for mid-March.
Some major cities in the American desert could approach or exceed 38 to 40°C, especially around Phoenix or Las Vegas. In several weather stations, monthly records for March are at risk, and some values could even rival records usually observed in April.
Such thermal intensity is very unusual at this time of year, just as the meteorological winter is barely ending.
Wave of heat in the USA © LCM
Millions of Americans affected for several days
This heatwave could last for almost a week, which reinforces its remarkable nature for the season.
Millions of residents of the American West are expected to face exceptionally high temperatures for mid-March, in a context already marked by a often very dry climate.
This early heat could also have significant hydrological consequences, with accelerated snow melting in the Rockies. In some regions, this situation could also worsen the drought conditions already present in the western United States.
A very unusual weather situation for the season
While heatwaves are common in this region in the summer, such an episode in mid-March remains particularly unusual.
Especially since on the other side of the USA, cold remains biting near the Great Lakes and Quebec, where snow and a new cold wave will be established at the same time.
