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Bombogenesis

weather bomb

Infrared satellite shot of the “cyclonic bomb” that hit the Aleutian Islands

Dutch Harbor, Alaska – bombed by the Japanese Navy during World War Two – was bombed again Sunday, but this time it was Mother Nature delivering the blow.

A huge, low-pressure weather system in the North Pacific Ocean created what the National Weather Service calls a “bomb cyclone” generated by bombogensis.

Boom!

The 4,400 residents of the community of Unalaska, which surrounds the port of Dutch Harbor about 900 miles southwest of Anchorage, were hunkered down and waiting out the blow.

Asked how bad things were on Sunday with winds blowing steady at 50 mph and gusting over 75 mph, Bong Tungul, manager of North Pacific Fuel, at first just laughed.

“Bad?” he asked when he stopped laughing on the end of the phone line. “That’s an understatement. It’s really bad. It’s gusting bad. Luckily, people got a heads up on this.”

Everything was pretty well battened down in Dutch by the time the storm made landfall, he said. Some windows were reported broken here and there around town, he said, and a couple boats broke loose in the harbor but were safely recovered.

Over at the Grand Aleutian Hotel on the island near the head of the Aleutian Chain, Rita at the front desk was a little hard to hear over the noise in the background. The hotel staff were having a Christmas decorating party, she said.

Outside, she added, “it’s really bad. I heard that they closed the road for a couple hours.”

The Grand Aleutian is a comfortable, modern, 112-room hotel with a restaurant and a bar. In other words, a good place to hunker down during a storm. It describes itself as “reminsent of a Europen chalet.”

In this case, a European chalet in a blow hole. “Dutch Harbor” and “notoriously bad weather” are pretty much considered synonyms in Alaska. Dutch is the home port for the Emmy-award-winning, reality TV show “Deadliest Catch,” so named for the many Bering Sea crab fishermen who fell victim to storms in the North Pacific south of the Aleutians and the Bering Sea north of the Aleutions.

Strongest storm on Earth

But even by Dutch standards, the storm that hit this weekend with winds gusting to hurricane force was unusual.

The Weather Channel called “it the strongest storm on Earth based on pressure at that time.”

“In the case of this weekend’s storm, the pressure dropped an incredible 55 millibars in 24 hours (1002 millibars 10 p.m. Friday Alaska time to 947 millibars 10 p.m. Saturday Alaska time),” it reported. “The pressure reading continued to drop and was at 944 millibars as of early Sunday.”

Bombogenesis is defined as an atmospheric pressure drop of 24 millibars in 24 hours. The Aleutian storm more than doubled the standard.

As the pressure drops in a counter-clockwise rotating low-pressure system, air is drawn in from outside the system and winds accelerate rapidly.

The Weather Channel was Sunday hot on how the storm was “presenting spectacular views on satellite imagery.”

Meanwhile, the National Weather Service was warning that it wouldn’t be so pretty on the ground. It had forecast winds gusting 90 to 100 mph in the Central and Eastern Aleutians with seas forecast to 50 feet.

A map of the storm zone posted on the Weather Service’s Facebook page was painted with a lot of red, and a storm update posted by the federal agency as a comment there warned  there is a possibility of a few gusts that could reach 120 mph in the Central Aleutians. Please be safe out there! “

The storm was expected to push east in Bristol Bay sometime on Sunday, and the weather service had posted a winter weather advisory calling for up to 8 to 11 inches snow probably driven by wind. But the system appeared to stall north of the Aleutians and spinning in the Bering Sea on Sunday night.

Seasonal snows fell in Bristol Bay communities early in the day with winds up to about 25 mph, but the snow had stopped and the winds were down by evening.

 

 

 

 

 

 

 

 

 

 

 

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