In a few days, on the first of March, the beginning of meteorological spring. Many ask when will it be warm? Meanwhile, winter has settled in. This will be influenced by the polar vortex. What can be seen in the numerical models for the following weeks in the weather? This was checked by our weather forecaster Arleta Unton-Pyziołek.
In early February 2023, extremely low temperatures swept over Northeastern United States and Southeastern Canada. Located in the state of New Hampshire, Mount Washington (1917 m) with a meteorological observatory survived record-breaking conditions. Meteorologists from around the world rubbed their eyes in amazement, witnessing an amazing phenomenon in the atmosphere, almost “epic freeze”, reminiscent of scenes from the catastrophic movie “The day after tomorrow”, as described by American researchers. We return to these events, because for several days we have been observing in the forecasters’ materials for Europe an interesting, but also a worrying cold snap in March, somewhat reminiscent of that situation.
On February 3 and 4, the wind at the top of Mount Washington was so strong that it broke the hinges on the observatory doors, and the meteorologist on duty at the time reported that exposed skin frostbite in less than a minute. The US National Weather Service (NWS) reported a record low air temperature of -46.9 degrees Fahrenheit (-43.3 C). “Right now, Mount Washington lives up to its reputation as having the worst weather in the world,” they concluded. Strong winds lowered the wind chill to -108 degrees F (-77 degrees C). The record-breaking cold on Mount Washington was greater than that experienced by the Curiosity rover NASA on Mars in the same week. In Canada, there was such a sharp drop in temperature that “cryoseism” occurred in many regions. It’s a seismic event, which is a weak earthquake caused by the rapid freezing of water in the ground, literally tearing the ground apart by “shock freeze,” as meteorologists call the phenomenon.
When will it be warm? The polar vortex cools hope
The cause of the whole phenomenon lies in the Far North. Years ago, the Polar Vortex over the North Pole was discovered and studied, a great cap of cold air swirling over the Arctic at 20-30 kilometers high, heavily weather-related and in temperate latitudes. At the end of winter, when the sun’s rays reach the circumpolar regions, the temperature in the cap rises and the vortex weakens. It is sometimes torn into fragments, visible close to the ground in the form of tongues of cold sliding down over Canada, the USA, Europe or Siberia. In simple terms, it looks like that in two to five weeks, the cold from 30 km altitude descends lower, closer to the surface of the earth and contributes to the creation of air vortices that suck in cold from above the Arctic and push upward warm, mild air masses from the ground layer . Today, the center of the waning polar vortex hangs over northwestern Russia and heads towards Asia. And a veil of its cold air (pale blue in the map below) at 30 km high extends over the Atlantic and Europe, meaning to the meteorologist that winter is not gone, just lurking and will strike.
The impulse to weaken the vortex and tear it apart is provided by the so-called stratospheric warming, monitored by the Japan Meteorological Agency. In recent weeks, the temperature over the pole at an altitude of about 30 km has increased from about -85 degrees C to about -15/-20 degrees C.
The phenomenon itself is natural, but its effects can be a shock and a threat to the inhabitants of the temperate zone. Canadians and Americans experienced this in early February. Europeans anticipating spring may feel the icy cold in the coming weeks. One of the tongues of cold is to slide over Europe, giving an impulse to the formation of cyclones in the circumpolar and temperate latitudes, pulling the Arctic air masses. In the light of the latest calculations of the global GFS meteorological model, there is a high probability that we will experience several waves of snow and frost by March 15.
We are observing a wave of cold right now in Poland, the next one is to appear between March 4 and 7. The most dangerous, however, is the tongue of cold predicted by the GFS model for around March 9/11. The air temperature at the height of 1.5 km above our heads is to drop to -10/-15 degrees Celsius. -25 degrees C. Meteorological observatories on Śnieżka and Kasprowy Wierch will be directly in the clean raw air mass from above the Pole. And although they do not record such a low temperature value as on Mount Washington, the landscape will look similar.
Such a strong invasion of air masses from the north in the first half of March gives little hope for the coming of a large warming in the second half of the month. The ECMWF (European Modeling Center) meteorological model calculates the decrease in the average air temperature below the long-term norm in the first decade of March, and the entry of cold from the north-west. Even in the last decade of the month, the average temperature is still below normal. However, deviations from the norm today do not look as dangerous as the GFS model would suggest. So there is hope that the cooling will not be so strong.
What was most surprising about the cold slide a few weeks ago over Canada and the US is that the cold from the stratosphere has descended spectacularly low. The top of Mount Washington literally spent some time in the stratosphere. It’s like a piece of land floating in the atmosphere like a space rocket launching from Cape Canaveral. The top of the mountain, just below 2,000 meters above sea level, found itself in a patch of polar vortex, and the extremely rapid cooling caused the atmosphere to be compressed from above. The boundary between the troposphere that lies closest to the earth and the upper stratosphere has significantly decreased. This phenomenon, which led to the glaciation of the northern hemisphere in just a few days, was shown in an exaggerated but very effective way in 2004 in the movie “The Day After Tomorrow”.
Transfer to the Arctic
But what happened on Mount Washington was the truest reality, not Hollywood fiction. The analysis of the German Meteorological Service DWD shows what the situation was then in the city of Maniwaki in the province of Quebec in Canada, near Mount Washington. An atmospheric survey (measurement of temperature and air pressure with altitude) made with a weather balloon showed how much the stratosphere had lowered, and how close the North Americans were to the movie script. There are many indications that our piece of Europe will move to the Arctic for a while in March. An unpleasant cooling awaits us, but also an interesting meteorological phenomenon. The situation is very dynamic, and day by day forecasts will certainly surprise both the recipients and the meteorologists themselves. This is a typical situation at the turn of winter and spring.
Main photo source: Adobe Stock/GFS/wetter3.de