Storm Ciara sweeps across Europe

Storm Ciara sweeps across Europe

9 February 2020 18:15 UTC– 10 February 09:30 UTC

Storm Ciara sweeps across Europe
Storm Ciara sweeps across Europe

Storm Ciara swept over many parts of Europe from 9-10 February 2020.

Last Updated

08, December 2020

By Vesa Nietosvaara and José Prieto (EUMETSAT)

Centered on Scotland, and then Scandinavia on the morning of 10 February, with a centre pressure 944 hPa , the stormy winds of Ciara (also known as Sabine) reached across almost the whole Europe, as far as the Balkans.

 The centre of Ciara's circulation between Scotland and Norway, on Meteosat-11 HRV, 9 February, 14:00 UTC
Figure 1: The centre of Ciara's circulation between Scotland and Norway, on Meteosat-11 HRV, 9 February, 14:00 UTC

As the storm travelled across Europe it generated a cold air trough behind the main front, which advected vorticity and instability, with some quiet intervals between the front and the trough.

The hourly Meteosat-11 RGB Airmass animation (Figure 2) shows most of Europe affected by Storm Ciara (except the Iberian peninsula and the south east), overnight from Sunday to Monday. The red hues indicate a sinking tropopause, which conveys instability and corresponds to the trough in the cold airmass.

 
Figure 2: Meteosat-11 Airmass animation, 9 Feb 11:12 UTC–10 Feb 08:57 UTC

According to the numerical models (Figure 3), warm air ahead of the cold front (marked with A) preceded the leading edge of cold front (marked with B), seen as a broad white cloud line in the satellite image. A separate cloud line is seen (on the image) in ochre colours within the cold airmass, associated with the cold air trough (C).

 Vertical cross section across the storm (along the white curved line on the right) shows the vertical structure of temperature (red solid lines for positive, blue dashed lines for below zero values on the left hand side), and equivalent potential temperature (black lines) near the cross section axis. Dense isolines of equivalent potential temperature show the location of atmospheric front.
Figure 3: Vertical cross section across the storm (along the white curved line on the right) shows the vertical structure of temperature (red solid lines for positive, blue dashed lines for below zero values on the left hand side), and equivalent potential temperature (black lines) near the cross section axis. Dense isolines of equivalent potential temperature show the location of atmospheric front.
 

The Dust RGB animation (Figure 4) shows the separation between the front A in deep red-black and the trough C in orange or peach colour.

Figure 4: Meteosat-11 Dust RGB animation, 9 Feb 18:15 UTC–10 Feb 09:30 UTC

During the course of Monday morning, a mosaic of different clouds could be seen on satellite imagery (Figure 5), including cirrus under gravity waves trailing on the front, cumular developments in Germany and northern Poland, and even clear snow in the eastern Alps.

 HRV-coloured with spectral channels 0.8 µm,1.6 µm and 3.9 µm, 10 February 09:00 UTC
Figure 5: HRV-coloured with spectral channels 0.8 µm,1.6 µm and 3.9 µm, 10 February 09:00 UTC
 

The evolution image of minimum 10.8 µm values, taken at hourly intervals during the night from Sunday to Monday (Figure 6), resembles gravity waves at the top of mesoscale thunderstorms, although the scale here is synoptic.

 Minimum image at infrared 10.8 µm for the period from 12:00 UTC on Sunday to 09:00 UTC on Monday.
Figure 6: Minimum image at infrared 10.8 µm for the period from 12:00 UTC on Sunday to 09:00 UTC on Monday.
 

The infrared-window RGB evolution image (Figure 7) shows, in black, the area most affected by the front's journey overnight until 08:00 on Monday. Ciara caused widespread disruption across Europe and at least seven people were reported to have died.

 Statistical processing of the Dust RGB animation above, showing the area in black affected by the frontal cloudiness.
Figure 7: Statistical processing of the Dust RGB animation above, showing the area in black affected by the frontal cloudiness.

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