The bright high at the turn of the year was replaced by a masked cold front on Tuesday night, which brought a few centimetres of snow to the north. A masked cold front is a normal cold front that only causes cooling in higher layers of air, while it gets warmer on the ground. This is the case when the air near the ground cools down considerably during an inversion and is cleared out by the frontal elevator and the associated wind and replaced by - relatively - warmer air. This makes the cold front unrecognizable and it can attack petrol stations in peace or something.
WeatherBlog 10 2016/17 | Arctic outbreak
Background to the alarm...
500hPa geopotential and surface pressure today, Wednesday, January 4 Meridional situation with high pressure in the west and strong low pressure in the Baltic Sea area. In between a strong N flow
.In any case, the high is gone for now. The cold front was followed by calm weather yesterday, Tuesday, but winter was already waiting in the wings: a small, drained low in the Atlantic supports the high off the west coast of Europe, directing warm air northwards. A storm depression with a very deep core lies over the Baltic Sea. A strong, stormy northerly current develops between the Atlantic high and the low. With the arrival of a frontal system embedded in the Baltic Sea low, precipitation sets in on the northern side of the Alps.
The Baltic Sea low taps into Arctic cold and shovels it into Central Europe. On Thursday, the axis of the Atlantic high will tilt slightly to the east and the flow in the eastern Alps will take on an easterly component, pushing in more cold air. In any case, the temperatures from Thursday to Saturday will be colder than they have been for a long time. This is called an Arctic Outbreak - the breakout from the Arctic prison could join forces with the masked cold front and form a wintry gang.
Medium-term
There are still a few uncertainties as to exactly what will happen from the weekend onwards. From today's perspective, it will be relatively sunny on Friday, while Saturday will be cloudy in the north. At present, it looks as if a north-westerly situation will establish itself in the near future. The Atlantic high will be virtually overrun by a low with a core east of Greenland and the flow will become more zonal. This would make it milder again with the influx of Atlantic air masses, but it would remain wet with further snowfall in the north and west into next week.
For the southern Alps, things are still not looking particularly good in terms of snow. The Balkan countries, Greece, parts of southern Italy and western Turkey, on the other hand, are likely to receive some precipitation again thanks to a Balkan low. The Italian Adriatic coast may also see some sea-effect snow (= the big version of the lake effect).
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![Temperatures in 850hPa. The purple blob dripping from the NE to Central Europe is the Arctic Outbreak. Click on the image if the GIF does not move.](/images/articles/2017/01/2210_wetterblog_10_2016-17_-/tempresult_hom4.gif)
Temperatures in 850hPa. The purple blob dripping from the NE to Central Europe is the Arctic Outbreak. Click on the graphic if the GIF does not move.
Temperatures in 850hPa. The purple blob dripping from the NE to Central Europe is the Arctic Outbreak. Click on the graphic if the GIF does not move.
Photo gallery
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Weather pattern at the Grimming station (STMK). With the arrival of the masked cold front, the temperature rises in the valley (purple line, 643m) because the inversion is cleared. At altitude, however, the temperature drops (red lines >2100m).
lawis.at -
500hPa geopotential and surface pressure today, Wednesday, January 4 Meridional situation with high pressure in the west and strong low pressure in the Baltic Sea area. In between a strong N flow
.meteociel.fr -
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500hPa geopotential and ground pressure on Friday, 6.1. The axis position tilts somewhat and the northerly flow gets an easterly component - optimal slide for Arctic air masses...
meteociel.fr -
500hPa geopotential and ground pressure, exemplary map for next Monday, 9.1. The high in the west no longer extends as far north, the flow becomes more zonal, option for NW position. Balkan low present
.meteociel.fr -
Anomaly (cm) of the current snow depth compared to the average of the period 1998/99-2011/12. Based on snow depth measurements and a model. Unusually high snowfall in the western half of Turkey
.https://www.ccin.ca/home/ccw/snow/current
This article has been automatically translated by DeepL with subsequent editing. If you notice any spelling or grammatical errors or if the translation has lost its meaning, please write an e-mail to the editors.
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hTranslated from German.