A sudden warming in the stratosphere opens up for freezing North Pole air over Norway. An unusually cold January is expected in large parts of the country.
The next month will be very cold. Photo: Espedal, Jan Tomas / Aftenposten
Sea view
Published: 29/12/2023 14:45
Tired of the cold? Then you have to steel yourself. The new year starts off cold – and it will stay that way.
In any case, if we are to believe the forecasts from the Meteorological Institute.
On Friday, the institute reports an atmospheric phenomenon that will create frost smoke throughout January. The phenomenon is called “abrupt stratospheric warming”.
– The way the forecasts are now, it will be unusually cold at least until January, says on-duty meteorologist Marek Ratajczak.
The jet stream breaks down
Why does it happen?
– It is a phenomenon that happens quite far above our heads, says Ratajczak.
The phenomenon takes place in the stratosphere, between ten and fifty kilometers above the ground. It is usually cold there, at this time of year between 70 and 80 degrees below zero. Now, warm air has suddenly come up instead, and the stratosphere has become much warmer, around zero degrees.
It affects the atmospheric winds.
– Normally, the stratospheric polar vortex moves counter-clockwise around the North Pole. This wind traps the cold air in the center of the vortex. When the stratosphere is heated, the polar vortex collapses, says Ratajczak.
This is how the meteorologists at X explain the phenomenon:
The North Pole air comes south
When the polar vortex collapses, the jet stream also weakens, he explains.
The jet stream is an atmospheric wind between the tropopause the tropopause This is the boundary between the troposphere and the stratosphere which are the two lowest parts of the atmosphere. and the stratosphere, between 7 and 17 kilometers from sea level. This is the wind that eastbound long-haul flights use to get there faster and save jet fuel.
When the jet stream breaks down, the icy air at the North Pole is free to travel south.
– When the jet stream breaks down, there will be outbreaks of cold air from the polar regions to fairly low latitudes, i.e. quite far south, says Ratajczak.
Will last a long time
The last time this happened was in February this year. Then the cold period lasted until well into March. The same will probably happen now.
– This event often leads to a prolonged cold period, says Ratajczak.
There are several things to remember when it gets cold outside. Here are five pieces of advice.
The snow weather is worst in the areas colored orange on the map. Here, up to half a meter of snow can fall from Sunday to Tuesday. Photo: Yr.no/X
Sea view
Southern and Eastern Norway can get half a meter of snow
In addition to the cold, people have to prepare for a lot of snow. The Norwegian Meteorological Institute has now issued an orange warning about the weather that is on its way.
From Sunday morning to Tuesday morning, large amounts are expected in parts of southern and eastern Norway.
– During the period, 20 to 50 cm is expected. In coastal areas in Agder, the precipitation can come as sleet or rain in periods, says a message on X.
In the yellow area, 10–25 cm is expected, while in the orange it can reach up to 50 cm.
Here are some of the recommendations from the meteorologists about the storm to come:
- Protect vulnerable installations and objects that cannot withstand the expected amount of snow
- Consider whether the journey is necessary
- Calculate a lot of extra time for transport and driving
- Use the right tires and drive according to the conditions
- Follow advice and check status from transport operators
- Check road announcements (175.no)
- The need for preparedness must be assessed continuously by emergency responders
Consequences:
- Vulnerable infrastructure can be hit as a result of the weight of the snow
- Many journeys may have longer journey times
- There may be generally difficult driving conditions
- The power supply may be affected
2023-12-29 13:45:39
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