Western Europe mild winter temperatures – Dec/Jan/Feb.  2018/19

Posting February 28, 2019

The unusual winter conditions can be easily attributed the North Atlantic and adjacent seas in Norther Europe. One low air pressure is followed by the next follows. They chase each other and push Siberian high pressure the cold air eastwards the Ural Mountains. Is this constellation that North America fell prey to extreme cold and snowy winter condition? By the end of January the US Midwest was paralyzed by winter freeze colder than Antarctica. Has the unhindered move of Atlantic cyclones across Europe eastward contributed?

It seems high time to ask whether human off-shore activities have contributed, as frequently discussed in previous posts; e.g. HERE & HERE. Up to a dozen of human activities at sea affect the sea water temperature structure, keeping the surface temperature during the winter season warmer. That has a profound impact on air temperatures, the weather and the the Polar Vortex.

According to WMO  this is a large area of low pressure and cold air surrounding the North Pole, with strong counter-clockwise winds known as the jet stream that trap the cold around the Pole. Disturbances in the jet stream and the intrusion of warmer mid-latitude air masses can alter the structure and the dynamics of the Polar Vortex, sending Arctic air south into middle latitudes and bringing warmer air into the Arctic. This is. WMO asserts, not a new phenomenon, although there is increasing research into how it is being impacted by climate change. But why does not cross their minds, that the sea, stirred by off-shore windfarms, shipping, fishing, and other activities, in sea areas of Europe cause  the Polar Vortex to deviate from its usual move?  

The WMO analyzed by Feb, 14 that the bitterly cold temperatures over large parts of large parts of North America are caused by the influence of the Polar Vortex that were gripped by an influx of Arctic air late January. The frigid air mass is also supporting heavy lake effect snows downwind of the Great Lakes. The US National Weather Service said that temperatures will be well below average over the Upper Mississippi Valley, Great Lakes, into parts of the Northern Mid-Atlantic. In southern Minnesota, the wind chill factor pushed readings down to minus 65°F (-53.9°C) on 30 January.  The national low temperature record was measured at minus 56 °F (-48.9°C). The WMO analysis offers not the slightest clue why the Polar Vortex happened.

Across the North Atlantic low-pressure areas generally dominated central Europe in January. Clouds and precipitation fields repeatedly pushed against the northern edges of the low mountain ranges and the Alps, causing extreme continuous snowfall there in some instances. Already at the start of December 2018 brought a change in the weather of Europe. High pressure areas that had dominated the weather for months mitigrated toward the east and were replaced by low pressure from the Atlantic. From now on the mild westerly flow prevailed, making December too mild, with 3°C higher than average (reference 1961-1990), with little sunshine and significant precipitation.(More details DWD)

 On Monday, 25th February, Britain saw its hottest winter day on record, with the mercury in the Welsh village of Trawsgoed hitting 20.6 Celsius (70 Fahrenheit). It was, according to the Met Office, the first time that temperatures had exceeded 20C on the British mainland in winter. On Tuesday the record was broken again with the Met Office reporting 21.2C at Kew Gardens in West London. Where weather is ending and begins climate, asks Amélie Bottollier-Depois in a recent essay titled: “Where’s winter? Western Europe basks in record temperatures”. That is by far too little.

The basic situation seems to be clear. North America freeze, Western Europe up to the Ural and beyond is enjoy mild conditions. Naming the Polar Vortex as cause explains a deviation from normal Jetstream conditions, but does not explain why it happens in the first place, and ignores the possibility that human activities across the North- and Baltic Sea, and elsewhere contributed to the extend and formation of the Polar Vortex during this winter. Science should be more interested in the possible role of man and the sea in the matter.