Storm David

Storm David (also called Cyclone Friederike in Germany) was a compact but deadly European windstorm that heavily affected the British Isles, France, Benelux, Central Europe, Northern Italy, Poland and parts of Eastern Europe in early 2018 with widespread hurricane-force gusts and severe snowfall, creating blizzard conditions in some areas. The storm caused extensive damage and traffic disruption. It was given the name David by Météo France while the FUB named it Friederike.

Meteorological history On 14 January a weak low pressure area in the Southern Caribbean developed a trough to its northeast. During the formation of the trough, weather in the North Atlantic was dominated by the strong Icelandic Low Fionn (called Evi by the Free University of Berlin) that itself brought windy conditions to Greenland, Iceland and Scotland and bottomed out at a very intense central low pressure of 935 hPa (27.6 inHg). At that time, a very intense jet stream was prevalent in the North Atlantic, driven by the powerful arctic low. Thus, two of the main global weather prediction centres, GFS and ECMWF, predicted Fionn to steer the new cyclone into Europe, leading to an impact on the British Isles and Continental Europe. By that time, the track and intensity of the new storm were not clear. Likewise it was unclear if the new weather feature would affect Europe as a cyclone or if it would remain an open trough until it arrives. By 16 January the trough now stretched from its Southern Caribbean origin to eastern Newfoundland. During that day, the trough developed a circulation centre near its northern end (Newfoundland), forming closed isobars around it which indicate a closed wind circulation and qualify the system as an extratropical cyclone. Hours after formation, the storm was caught by Fionn's strong jetstream and started moving to the east, posing a threat to Europe. While crossing the Atlantic, David once again lost some structural definition and opened up into a trough under the strong influence of Fionn. The weakened David was racing eastward through the North Atlantic, taking aim at the British Isles. Meanwhile, the ECMWF and GFS lowered their predictions concerning David's intensity as it was unclear if the system would be able to recover from the structural deterioration that was inflicted by Fionn. David would cross the North Atlantic in less than two days. While David was approaching Ireland in the evening of 17 January, Fionn started to weaken as its centre began to fill. David managed to redevelop a closed circulation while passing over the British Isles and the North Sea in the morning of 18 January, worsening the risks for Central and Eastern Europe. Britain received some hurricane-force gusts up to 150 km/h (93 mph). Subsequently, the storm had some hours to gain additional energy while moving quickly over the North Sea before making landfall in the Netherlands. The cyclone's minimal pressure bottomed out at 974 hPa (28.8 inHg) while centred over the North Sea, which was substantially lower than predicted by GFS and ECMWF. Hoek van Holland, where the storm made the first of its two landfalls in the Netherlands, experienced wind gusts up to 143 km/h (89 mph). Moving on, the winter storm rampaged in Germany, disrupting public transport services as it already did in the Benelux and causing ten deaths on 18 January. While centred over Germany, the storm still was near peak intensity, having a central pressure between 976 and 979 hPa (28.8 and 28.9 inHg), and caused widespread gusts in the 121–137 km/h (75–85 mph) range, with gusts up to 203 km/h (126 mph) on mountains. During the evening of 18 January, the eastward moving centre of David crossed the Polish border and weakened to 985 hPa (29.1 inHg). David weakened to a regular low pressure area as its winds fell below storm force on 19 January. It continued its eastward motion through Belarus and the westernmost part of Russia. The southern flank of the low also affected the weather in Slovakia and Ukraine. On 22 January 2018, being located over western Russia, David merged with another weak low that was located over Scandinavia. Thus, David dissipated as a meteorological entity.

David was a compact and fast-moving cyclone, which is typical for systems that are steered by strong Icelandic lows which develop a strong easterly flow on their southern side. Similar to Fionn, David itself had its main wind field located to the south of its centre; the northern semicircle featured comparatively low winds but was more intense in terms of precipitation. Heavy snowfall occurred on the northern flank of the storm, causing blizzard conditions in some areas.

Impact

Beginning on 16 January, prior to David's arrival, the very deep and large arctic low Fionn battered the British isles with high winds. Storm conditions also occurred in other parts of Western and Central Europe in the middle of January 2018 (even affecting Corsica). The intense winds were caused by an extensive "squeeze in isobars" that, probably amongst other meteorological factors, was caused by Fionn's great depth and extension. During that time, David was crossing the Atlantic and fluctuated in intensity, leading some models to a rather optimistic forecast. Nevertheless, David managed to begin a strengthening trend while crossing the British isles the night between 17 and 18 January. Thus, the fast-moving cyclone delivered winds up to 153 km/h (95 mph) and heavy snowfall in Britain, creating blizzard conditions there. Windthrown trees blocked roads and rail routes. Approximately 140,000 households in Britain were temporarily without power.

The Netherlands were even worse affected by the cyclone. All flights were cancelled at Amsterdam Airport Schiphol. The rail transportation system was also completely defunct due to windthrow. Because of thrown trees and high winds, road traffic was, as well, nearly impossible and life-threatening. Winds up to 140 km/h (87 mph) knocked down trucks and cost three people's lives in the Netherlands. In the neighbouring country of Belgium, similar conditions occurred, leading to the death of one woman. Furthermore, while the cyclone was centred over the Benelux, the northern French region of Hauts-de-France was lashed by winds up to 122 km/h (76 mph).

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