Where we are heading at breakneck speed towards a green, changeable and rather soft Christmas in the Netherlands, large parts of America will have to deal with an equally rapid, but also violent outbreak of arctic cold. In a few days, a wave of extremely cold air, coming from the freezer in the interior of Canada, falls over the eastern two-thirds of USA. In most places it will be a flash winter, but during the Christmas period it will be one to never forget.
Ice cold is the air that will pour out over North America in the coming days. Driven by the southern branch of the polar vortex, the cold really plunges to the South. This happens between an explosively deepening low-pressure area, a so-called’ bomb cyclone’, and a strong high-pressure area directly behind it.
The fluctuations in temperature will be enormous. If the mercury is still above zero one moment, the other moment it starts to snow, after which the mercury then drops to sometimes below -20 degrees in a short time. Over the course of Thursday and Friday, the freezing cold even seems to reach the coast of the Gulf of Mexico and Florida. It also gets particularly cold there. In many places, the cold brings snow. Most of it seems to fall around the Great Lakes in the North, locally more than half a meter. Although it is already warming up during the Christmas days, in many places Christmas will be white.
As soon as the cold comes, it disappears again in the days after Christmas. Although this is only for a while in the north of the USA, because there is the passage of a second wave of arctic cold on the program for later next week.
We all know that the weather in the USA has greater extremes than in Europe. But sometimes it can be really very extreme, like the next few days. Since there are no mountains or seas to stop the cold, if it comes rushing in from the North, extreme fluctuations in temperature can occur. Examples of cold fronts are known, which separate an air mass with a temperature of around or even above 20 degrees on the south side from air with a temperature of -20 degrees on the north side. The greater the temperature differences on both sides of the transition zone, the more extreme the weather phenomena that occur on the front.
A low-pressure area, which forms in the transition zone (and often – now also – happens on the eastern side of the Rocky Mountains), can explosively deepen. Such a low-pressure area, which is rapidly gaining strength, is called a “bomb cyclone” in the USA. The Depression of the next few days arises east of the Rocky Mountains and ends up in the Great Lakes area a day later. It is there that the system, with an air pressure of around 960 hPa in the core possibly for some time, reaches its greatest strength.
The pressure differences with the high pressure area directly behind it can be up to 90 hPa. This means that in many places, even if we are talking about the interior, it is also going to storm. This, combined with the expected snowfall and the low temperatures, means that the visibility in drifting snow can be reduced to only a few meters. So, a frenzied Blizzard is also expected, just at the time when many Americans are traveling in connection with the Christmas holidays.
Even though the winter period of the coming days in the US lasts only a few days, the weather that comes with it is so extreme in many regions that it can still turn into an extreme event that many people will remember for a long time.
About the author: Matthew Johnson
Matthew Johnson, a small tech business owner retired and found his passion in journalism.