On 18 January 2018 an Atlantic depression crossed parts of Western Europe bringing very strong winds and heavy rain.
By Ian Mills (Ian Mills Consulting)
As the depression approached the UK it was just about to deepen further. By the time the depression had crossed the North Sea and the coast of Germany it was at its deepest, bringing strong and damaging winds to eastern England, northern France and Belgium, but more especially to the Netherlands and Germany. In Germany (where the storm was officially named Friederike) the at least eight people were reported to have died as a result of the storm.
Figure 2 displays Meteosat-10 Airmass RGB imagery overlaid with the 00z run of the GFS (Global Forecast System) model from 00 UTC to 24 UTC on 18 January. The white curl of cloud around the top of the low shows the position of the frontal cloud which brought heavy precipitation across the UK and into other parts of western Europe.
The red-brown colour to the south of this cloud becomes more pronounced as the depression moved east across the North Sea and into Europe — this is a typical signature that the low was deepening.
This is supported by the model pressure field showing a central pressure of about 986 hPa over the Irish Sea at the start of the sequence, deepening to 978 hPa as it crossed the coast of Germany.
A typical pattern can also be seen in the pressure field where a very tight pressure field appears on the southwestern side of the low. This area coincides with the 'hook' of cloud coming round the back of the low. The strongest winds around the depression were located in this area.
As the low crossed northern Germany the Airmass RGB imagery begins to show a much less organised structure around the low, suggesting the low development was over and it was starting to fill. This is confirmed in the model pressure field.
Deepening had stopped by the time the depression reached western Poland and the low was beginning to fill.
Figure 3: Meteosat-10 infrared animation, 18 January 00:00 UTC to 24:00 UTC. Download animation (MP4, 3 MB)
On the Meteosat-10 infrared animation (Figure 3), as the depression crossed Germany, a finger-like structure can be seen in the white cloud, moving south-eastwards on the western side of the low. This suggests the existence of a sting jet which may have been responsible for the extremely strong gusts of wind across the Netherlands and Germany.
The Water Vapour animation from 0000 UTC to 2400 UTC on 18 January 2018 is overlaid with the 300hPa contours from the GFS model (Figure 4). At the start of the sequence a darker area can be seen on the water vapour imagery across the Irish Sea, this coincides with a short wave trough.
As the sequence progresses the dark area on the water vapour imagery becomes even darker and the contours show a left exit area of the jet stream. Typically, this shows an area of development at the surface, and, hence, the deepening of the surface depression.
The Dutch met service, KNMI, reported wind gusts of up to 140 km/h (75 knots) in the southern port of the Hook of Holland, as the storm passed over the Dutch coast. Similar speeds were reported in Northern Germany resulting in the cancellation of rail services.
Also in the Netherlands at 12:00 UTC De Kooy reported a wind of NW 64 gust 104 km/h and Vlissingen reported a wind of NW 47 gust 119 km/h.