Bomb cyclone in Pacific expected to pound Alaska

A powerhouse storm explosively intensifying in the northern Pacific could rank as the strongest nontropical cyclone observed in that ocean basin.

The storm’s pressure dropped to 921 millibars on New Year’s Eve, which is even lower than extreme cyclones that formed in the same vicinity in 2014 and 2015. It now qualifies as the strongest storm on record to hit Alaska, according to Rick Thoman, a climate scientist at the University of Alaska at Fairbanks.

The lower the pressure, generally, the stronger the storm. The two northern Pacific cyclones that set records in 2014 and 2015 saw their pressures level off at around 924 millibars, which means this storm has eclipsed their intensities.

On Thursday morning, the National Weather Service’s Ocean Prediction Center confirmed that the storm was generating 110 mph winds. On satellite imagery, the storm appears as a giant comma-shaped swirl of clouds, a textbook appearance for a strong nontropical weather system. The Weather Service’s Ocean Prediction Center said the cyclone ranks as “one of the strongest storms to ever impact the North Pacific.” The strongest wind gust recorded at Shemya Island in Alaska, about 1,450 miles southwest of Anchorage, was 83 mph, with high winds and pounding waves battering the western Aleutian Island chain.

This 2020 Pacific bomb cyclone and its ultralow pressure represent an amazing contrast from an exceptional high-pressure zone over Mongolia, which may have set a world record Tuesday.

At 7 a.m. local time Tuesday, the mean sea-level pressure at Tsetsen-Uul, Mongolia, rose to 1,094.3 millibars, about 174 millibars higher than the projected pressure in the Pacific cyclone.

East Asia sits in the transition zone between these two extreme pressure centers, and the resulting northerly winds funneling over the Sea of Japan are predicted to cause a massive “sea effect” snowstorm for the Japanese Alps downwind.

Multiple feet of snow are forecast for the high terrain on Honshu through Saturday morning. This same region is just recovering from up to seven feet of snow earlier this month.

Meanwhile, the Pacific storm, in addition to unleashing winds topping 100 mph, is predicted to generate waves over 45 feet.

Such storms generally go unnoticed except for meteorologists and those with maritime interests such as shipping, military and fishing. They are common in winter, although this storm is likely to reach the upper echelon of those ever observed in terms of its intensity.