LONDON (AP) -- Enormous waves churned across the North Atlantic on Saturday as Britain braced for a second straight weekend of wild winter weather and flooding. Hundreds of flights were cancelled, and the Royal Navy joined the search for a missing man who went overboard a boat.
Hurricane-force winds of up to 85 knots (98 mph) and monster waves that could reach over 100-feet-high ((30 meters)) were roaring across the North Atlantic, the U.S. National Weather Service's Ocean Prediction Center reported.
The fourth storm of the winter season, dubbed Dennis by Britain's Met Office weather service, was sweeping through Ireland into Britain and causing widespread travel disruptions that were expected to worsen over the day.
The Met Office had 18 flood warnings in place around England, which meant flooding was expected. The Irish Meteorologist Service issued a number of wind warnings, saying gusts of up to 120 kilometers per hour (75 mph) might be seen. Gale warnings were also issued in Iceland.
The weather is expected to strike all areas of Britain, including parts of northern England still recovering from Storm Ciara last weekend. That storm left at least eight people dead across Europe, including two in the U.K.
A search-and-rescue operation off the coast of Margate in southeast England was looking for a man who reportedly fell from a vessel just before dawn. A Royal Navy vessel joined in the operation alongside lifeboats from the Royal National Lifeboat Institution and a police boat.
Airlines preemptively canceled hundreds of flights out of London and other U.K. airports, and railways warned about possible train delays and cancellations. Tens of thousands of passengers were being affected on a busy travel day for British families, as most schools in the country closed down for a mid-winter break.
Easyjet cancelled around 230 flights in and out of the country as wind speeds are set to hit 70 mph (113 kph). British Airways also cancelled flights.
Areas in northern England, which are still recovering from Ciara, faced up to 4 1/2 inches (120 centimeters) of rain on Saturday. The country's Environment Agency said flooding is likely to be worse than last weekend — when hundreds of homes were flooded as river burst their banks — since the rain will be falling on saturated ground.
Around 75 British army personnel and 70 reservists were helping out stretched communities in the flood-hit Calder Valley region in West Yorkshire, constructing barriers and repairing damaged flood defenses.
"Our armed forces are always ready to support local authorities and communities whenever they need it," Britain's Defense Secretary Ben Wallace said. "The rapid response of the Army today will help with provision of flood relief to local communities in West Yorkshire."