Storm Dennis exploded into a “bomb cyclone” during the early-morning hours on Thursday as the looming weather system poses a new windstorm threat for Europe just days after deadly Storm Ciara triggered widespread travel disruptions from the United Kingdom to Germany.
Storm Dennis was officially named by the UK Met Office on Tuesday, making it the fourth-named windstorm of the season by collaboration of Ireland, the U.K. and the Netherlands. Windstorm season traditionally runs from September through the end of April.
Dennis rapidly intensified over the northern Atlantic Ocean, allowing the central pressure of the storm to plummet 1.38 inches of mercury (46 mb) over a 24-hour period. This drop classifies Dennis as a bomb cyclone as of early Thursday morning.
This incredible drop in pressure is almost two times greater than what is needed to be considered a ‘bomb cyclone,’ which is defined by meteorologists as a pressure drop of 0.71 of an inch of mercury (24 mb) over a 24-hour period.
Storm Dennis intensifies over the North Atlantic Ocean on Thursday, February 13, on its approach to Europe (Photo/RAMMB).
Towering waves of 40 to 50 feet high will be widespread near the center of the powerful storm with the potential for some waves to top the 50-foot mark. The tallest waves will remain at sea, but the Atlantic-facing coastlines of the U.K. will be hammered by unrelenting waves as the center of Dennis nears the region.
Just days ago Storm Ciara caused nearly 1 million power cuts, widespread travel disruption and at least five deaths as it battered northern Europe from Sunday into Tuesday.
Storm Dennis will pack an extra punch and be quite impactful due to weakened structures and ongoing flooding left behind after Ciara.
A tree lies on a car in Hamburg, Germany, Monday, Feb. 10, 2020. A storm battered the U.K. and northern Europe with hurricane-force winds and heavy rains Sunday, halting flights and trains and producing heaving seas that closed down ports. Soccer games, farmers’ markets and cultural events were canceled as authorities urged millions of people to stay indoors. (Daniel Bockwoldt/dpa via AP)
In the days before Dennis’ weekend arrival, a separate fast-moving storm spread rain and gusty winds from the British Isles to France and Germany into Thursday. Another band of rain and gusty winds will cross the British Isles on Friday.
As Dennis approaches the British Isles on Saturday morning, wind and rain will increase. The heaviest rainfall will occur from Ireland into Northern Ireland and western Scotland.
During the afternoon, powerful winds will be felt across all of Ireland and the U.K. with downpours soaking Scotland, England and Wales. Showers are forecast for the rest of the region.
Frequent wind gusts of 40-60 mph (65-97 km/h) are expected during the midday and afternoon hours with powerful gusts continuing into Saturday night.
The hardest-hit locations, most likely in western Ireland or along the North Sea coast, can receive an AccuWeather Local StormMax™ wind gust of 137 km/h (85 mph).
Significant travel disruptions are possible again, including ferry and rail service as well as air travel.
Flooding will also be a widespread concern as soil is already saturated following Storm Ciara.
Total rainfall through Sunday is expected to average 25-50 mm (1-2 inches) across Ireland and the U.K. with an AccuWeather Local StormMax™ of 100 mm (4 inches).
Severe flooding in the hardest-hit locations may result in numerous road closures and some damage to homes and businesses.
Powerful winds and showers will continue across the region on Sunday and Monday.
Dennis’ impacts will be far-reaching, impacting other areas of Europe recently pounded by stormy conditions. Locations from northern France into Belgium, Netherlands, Denmark and Germany will be lashed by rain and powerful winds from Dennis on Saturday night and Sunday.
Locally damaging winds will then expand into northern Poland and the Baltic states on Sunday.
Wind gusts of 40-60 mph (65-97 km/h) are expected during the worst of the storm for most locations; however, coastal areas from northern France to Denmark will be at risk for gusts up to 70 mph (113 km/h)
Localized flooding and travel delays are expected across northern Europe as the worst of the storm impacts the region.
A period of more tranquil weather will then be possible across northern Europe during the second half of next week.
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