Alaska Got 15 Inches of Snow in 90 Minutes Last Week

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iStock

Alaska is obviously no stranger to snow, but this month's white weather will likely go down in the state's record books. As The Weather Channel reports, Thompson Pass—a 2805-foot-high area in Alaska’s Chugach Mountains—received a whopping 15 inches of powder in just 90 minutes on Wednesday, December 6.

Thompson Pass sits just outside of Valdez, a tiny port city on Alaska’s south coast. Located along the Gulf of Alaska, Valdez is perhaps best known for the infamous 1989 Exxon Valdez oil spill, and for its rich Gold Rush history. Today, it’s important for commerce, since it’s the northernmost ice-free port in North America. But ice-free doesn't mean blizzard-free: The city is regularly cited as one of the snowiest places in the U.S., if not the snowiest. On average, locals can expect to see (and smell) 300 or more inches of frozen precipitation per year. As for Thompson Pass, it very often receives more than 700 inches of the wet stuff in a year.

Still, Mother Nature truly outdid herself on December 6, when Thompson Pass was slammed with what weather historian Christopher Burt deemed to be one of modern history’s most intense snowfalls. By the storm’s end, 40 inches of heavy snow had accumulated in just 12 hours, according to The Washington Post.

Who angered the winter weather gods? Or, more scientifically speaking, which atmospheric conditions led to the storm? According to experts, a stream of warm water vapor from the Pacific Ocean hit Alaska’s coast, traveling through an aerial channel known as an “atmospheric river.” When atmospheric rivers hit land, they release this water vapor as either rain or snow, according to the National Oceanic and Atmospheric Administration.

Intensifying the phenomenon was the North American Winter Dipole, which The Washington Post’s Jason Samenow described as a “fancy term to describe abnormally warm conditions in the West and cold conditions in the East.”

"Under such a pattern, the jet stream, the super highway for storms that divides cold and warm air, surges north in the western half of the nation, and crashes south in the eastern half,” Samenow said.

Valdez residents are accustomed to snow, but last week's storm was particularly challenging for townspeople. An avalanche buried Richardson Highway, the city’s only overland route that leads in and out of town. It reopened on Thursday, December 7, according to The Cordova Times, but driving conditions were poor.

While extreme, the Thompson Pass blizzard might not be history's weirdest snowfall. For example, arid countries like Kuwait and Iraq have experienced snow. In January 1887, 15-inch snowflakes were reportedly spotted at Montana’s Fort Keogh. And in 1921, over six feet of snow fell between April 14 and April 15 in Silver Lake, Colorado—the most snow to ever fall in a 24-hour period in the U.S.

[h/t The Weather Channel]

Storm Leaves Homes Along Lake Erie Covered in Up To Three Feet of Ice

Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
Houses along Lake Erie's shoreline were pummeled with sheets of icy water during a storm last week.
John Normile/Getty Images

This past weekend, lakeside residents of Hamburg, New York, awoke to find their neighborhood transformed into a full-scale replica of Frozen’s ice-covered kingdom, Arendelle.

According to CNN, gale force winds produced giant waves that sprayed the houses along Lake Erie with sheets of water for two days straight, covering them in layers of ice up to three feet thick.

“It looks fake, it looks surreal,” Hamburg resident Ed Mis told CNN. “It’s dark on the inside of my house. It can be a little eerie, a little frightening.”

While the homeowners are anxious for the ice to melt, they’re also concerned about what could happen when it does.

“We’re worried about the integrity, of structure failure when it starts to melt, because of the weight on the roof,” Mis said.

He added that this is the worst ice coating he’s seen since he moved to the area eight years ago—but it’s not because they’ve had a particularly harsh winter. In fact, just the opposite is true. According to The Detroit News, warm winter temperatures have caused ice cover on the Great Lakes to drop from 67 percent in 2019 to less than 20 percent this year.

“Lake Erie typically has significant ice cover by this time of the year, and that protects the shoreline from these battering storms,” The Weather Channel’s winter weather expert Tom Niziol explained in a video.

The phenomenon has created another unforeseen issue for Hamburg’s coast, too: Tourism. The local police department posted a message on Facebook on Sunday, March 1, asking people to keep off both the “extremely unsafe and unstable” ice and people's private property.

[h/t CNN]

What is Lake-Effect Snow?

Tainar/iStock via Getty Images
Tainar/iStock via Getty Images

As you probably guessed, you need a lake to experience lake-effect snow. The primary factor in creating lake-effect snow is a temperature difference between the lake and the air above it. Because water has a high specific heat, it warms and cools much more slowly than the air around it. All summer, the sun heats the lake, which stays warm deep into autumn. When air temperatures dip, we get the necessary temperature difference for lake-effect snow.

As the cool air passes over the lake, moisture from the water evaporates and the air directly above the surface heats up. This warm, wet air rises and condenses, quickly forming heavy clouds. The rate of change in temperature as you move up through the air is known as the "lapse rate"; the greater the lapse rate, the more unstable a system is—and the more prone it is to create weather events.

Encountering the shore only exacerbates the situation. Increased friction causes the wind to slow down and clouds to "pile up" while hills and variable topography push air up even more dramatically, causing more cooling and more condensation.

The other major factors that determine the particulars of a lake-effect snowstorm are the orientation of the wind and the specific lake. Winds blowing along the length of a lake create greater "fetch," the area of water over which the wind blows, and thus more extreme storms like the one currently pummeling the Buffalo area. The constraints of the lake itself create stark boundaries between heavy snow and just a few flurries and literal walls of snow that advance onto the shore. The southern and eastern shores of the Great Lakes are considered "snow belts" because, with winds prevailing from the northwest, these areas tend to get hit the hardest.

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