Satellite image overlaid with air pressure at sea level on Monday, February 6, 2023, 12 UTC. On Monday, a high pressure area was located northwest of Switzerland over the British Isles, causing a bise situation in the Central Plateau.
Satellite image overlaid with air pressure at sea level on Monday, February 6, 2023, 12 UTC. On Monday, a high pressure area was located northwest of Switzerland over the British Isles, causing a bise situation in the Central Plateau. (MeteoSwiss)
When there is a bise situation, there is usually a high pressure area to the north-west or north of Switzerland. The current bise situation was unusual in that the bise in the German-speaking Swiss Mittelland freshened up in gusts during the night into Tuesday, reaching the highest wind speeds. This was caused by a low pressure system that moved from Austria over the Swiss Alps to southern France during the night.
Satellite image overlaid with precipitation data and geopotential at 500 hPa from Tuesday, February 7, 2023, 00 UTC. A low pressure system crossed the Swiss Alps and caused a gusty increase in the bise during the night.
Satellite image overlaid with precipitation data and geopotential at 500 hPa from Tuesday, February 7, 2023, 00 UTC. A low pressure system crossed the Swiss Alps and caused a gusty revival of the bise during the night. (MeteoSwiss)
The low pressure at high altitudes increased the wind at high altitudes, and on the other hand, a stable cold air lake was unable to form above the ground. The bise usually decouples from the lowest altitudes at night and therefore dies down. At higher altitudes, however, it can sometimes blow even more strongly at night than during the day.
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Gust peaks superimposed with wind feathers from the weather qatar phone number library model COSMO-1E for Tuesday, February 7, 2023, 3 UTC. The channeled bise is visible in the Central Plateau and the south foehn over the Alps.
Gust peaks superimposed with wind feathers from the weather model COSMO-1E for Tuesday, February 7, 2023, 3 UTC. The channeled bise is visible in the Central Plateau and the south foehn over the Alps. (MeteoSwiss)
South Föhn – Guggiföhn
In the second half of the night and in the morning hours, a strong southerly foehn phase temporarily set in in the Alps. The foehn has been discussed in detail in the blog many times.
In the classic case, a south to southwest flow on the front of a low west or northwest of Switzerland brings moist air to the southern slopes of the Alps.
Classic south foehn situation
n January 21, 2021 with a low near the British Isles. top 5 iconic spanish-speaking authors Switzerland is on the front side in a south to southwest current.
Classic south foehn situation on January 21, 2021 with a low near the British Isles. Switzerland is on the front side in a south to southwest current. (Analysis map of the German Weather Service DWD, germany cell number from the archive of wetter3.de)
On Tuesday morning, however, high air pressure prevailed over large parts of Europe. Despite this, a southerly foehn phase set in briefly. This can be attributed to the shift of the high pressure area north of the Alps and to a change in the upper air flow in connection with the low pressure mentioned above.
The centre of the high pressure system slowly moved eastwards yesterday and today, Tuesday, was in the region of eastern Germany, Poland and the Czech Republic with its high air pressure of 1042 hPa. As a result, cold and moist air flowed along its eastern flank from south-eastern Europe over the Adriatic and the Po Valley to the southern slopes of the Alps.