“This is a dangerous storm that will cause widespread coastal flooding south of the Bering Strait with water levels above those seen in nearly 50 years,” the National Weather Service’s Fairbanks office wrote in its Friday morning forecast discussion. Ahead of the dangerous storm, the National Weather Service has issued several warnings to account for a plethora of hurricane-like threats.
Threats of high winds and coastal flooding As the power system approaches Alaska late Friday, gusty south-southwesterly winds will batter the state’s west coast. Huge amounts of water, pushed north by strong winds, will crash ashore, raising the ocean up to 12 feet and hitting vulnerable coastal communities with severe erosion. The storm will likely stall just off the Seward Peninsula over the weekend, continuing to push the Pacific toward Alaska’s vulnerable coastline. “The duration of high water is quite a bit longer than we often see, so it will lead to a longer duration of high water and waves pounding the shoreline,” said Ed Plumb, senior hydrologist at the National Weather Service’s Fairbanks office. , he told the Washington Post. Coastal flood warnings and high wind warnings have been issued, both remaining in place until late Saturday night, while gale warnings have been raised at sea to warn mariners of extremely dangerous conditions. The strongest storm in a decade is moving into the Bering Sea. The effects may exceed the 2011 Bering Sea superstorm, and some locations may experience their worst coastal flooding in nearly 50 years. Peak water levels will remain for 10 to 14 hours before the water recedes. #akwx pic.twitter.com/l1Ik4iXYBG — NWS Fairbanks (@NWSFairbanks) September 15, 2022 Gusts will exceed 90 mph in some spots, with hurricane gusts of up to 80 mph expected in and around Nome, which is known to be the finish line of the famed Iditarod Trail Sled Dog Race. Water levels in the coastal town of 4,000 are likely to reach 8 to 11 feet above high tide. In nearby Golovin, water levels will be even higher, pushing 9 to 13 feet above the normal high tide level, according to the Weather Service. In Nome and other villages along the northern Bering Sea, Plumb worries that water pushed into communities by strong southwesterly winds will flood structures, wash out key roads and damage important infrastructure. Gusts of up to 90 mph could also easily bring down power lines and cause other damage. The massive storm surge and giant waves that can top over 50 feet would cause severe beach erosion any time of year, but the fact that the storm hits in September increases the risk of erosion. In addition to the storm surge, this storm will also bring very strong winds to the west coast. Winds may gust up to 90 mph in areas such as Savoonga, Diomede and the Bering Strait. Other areas can expect gusts in the 70s, with gusts as high as 80 mph possible. #akwx pic.twitter.com/gG95I6XyOb — NWS Fairbanks (@NWSFairbanks) September 15, 2022
The perils of a September storm When huge, extratropical storms cross the Bering Sea, it’s usually later in the year — particularly in November and December. By this time, sea ice has built up along the coast, preventing significant wave action. But with this big storm hitting in September, the coastline is without an ice barrier, making it particularly vulnerable. “This will be the deepest low we’ve ever seen in the northern Bering Sea in September,” Plumb said, adding that this would be a powerful storm any time of year. “It follows the perfect textbook path to a major storm in the northern Bering Sea.” A September strike is also worrisome because it’s still hunting season in September, meaning hundreds of people could be hunting in the remote Alaskan wilderness and not receive storm updates. The road that many hunters and Alaskans use to travel inland, the Nome-Council Road, may end up washed out by the storm, leaving off-grid hunters stranded in the wilderness. The system is similar to a destructive storm from November 2011, when a comparatively intense non-tropical low spun over far eastern Russia, just inland from the Bering Strait. That month, too, the Pacific was forced inland. in Nome, roads and a sewage plant were flooded, while some low-lying coastal communities saw significant erosion caused by pounding waves. “In the Nome region, or that part of the southern Seward Peninsula, everything is well on its way and looks like [this storm] it will be as bad or worse than the 2011 superstorm,” Plumb said. In the Fourth National Climate Assessment, a comprehensive report on climate change published in 2018 — scientists expressed concern that climate change has set the stage for greater impacts from major non-tropical cyclones in Alaska. Warmer summers and oceans have caused greater-than-normal seasonal loss of sea ice, making the region more vulnerable to ocean flooding. “For coastal areas, damage from late fall or winter storms is likely to be exacerbated by lack of sea ice cover, high tides and sea level rise, which can increase structural damage to tank farms , homes and buildings and may threaten loss of life from flooding,” the report says. The report adds that rates of coastal erosion have accelerated, with some spots on the coastline losing up to 100 feet of land to the sea each year. “Longer sea-ice-free periods, higher land temperatures and associated sea-level rise are expected to exacerbate flooding and accelerate erosion in many areas, leading to loss of terrestrial habitats and cultural resources and claiming entire communities, such as Kivalina in the northwest Alaska, for relocation to safer ground.”
A meteorologically perfect storm The powerful weather system about to blast Alaska is, atmospherically, something of a perfect storm. The remnants of Merbok, once a Category 1 Pacific hurricane, will merge with a pair of non-tropical storms as it heads toward the Bering Strait, the thin strip of water between Russia and Alaska. Hurricanes — the Western Pacific equivalent of hurricanes — run on energy from the warm ocean water that’s common near the equator in late summer. This is in contrast to extratropical cyclones, which operate on energy stored in atmospheric temperature gradients. When the two types of systems merge, the combination can result in an extremely powerful storm forming in a short period of time. This system is forecast to strengthen explosively as it approaches the Alaskan coastline. The system’s pressure is expected to drop 24 millibars in 24 hours, meaning the storm will have met the criteria for what is known as a weather bomb or ‘bomb cyclone’ due to its rate of intensification. No need to duck and take cover — this is the “bomb cyclone,” he explained Such a process greatly strengthened Sandy as it approached the Mid-Atlantic in 2012 and will dramatically intensify the Pacific storm as it approaches Alaska. By Friday night, atmospheric pressure at the center of the storm — which is set to be over the ocean, a few hundred miles southwest of the Russia/Alaska border — is projected to bottom out at about 940 millibars. Low pressure pulls air in quickly, like a vacuum, and values below 950 millibars are usually only seen in Category 3 or Category 4 hurricanes. But because the storm, at this point, will be something of a hybrid between a tropical and non-tropical low, the wind field won’t mimic that of a Category 4 hurricane. Instead, all that energy will be spread over a larger area, with lower maximum sustained wind speed – probably around 90 mph – but with a much longer range.
