The evolving blob: Warmer ocean temperatures to continue around Alaska's coast

View of Anchorage from the KTUU weather camera.
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ANCHORAGE (KTUU) For the past two years, we’ve been watching a large, fairly-defined area of warmer-than-normal sea surface temperatures in the Pacific Ocean. “The Blob” as it’s called developed in the winter of 2013/2014 when a persistent area of high pressure formed over the Northern Pacific.

Scientists have speculated the Blob might be partially responsible for impacts to several species of animals including a high number of stranded sea lions off the California coast.

The Blob, though persistent, is now evolving according to Rick Thoman, Climate Science and Services Manager for the National Weather Service Alaska Region.

“We don’t just have a round area of above normal sea surface temperatures in the central and north Pacific,” says Thoman. “We have evolved into a very typical positive PDO (Pacific Decadel Oscillation) pattern.”

The PDO is a reoccurring pattern of cooler and warmer temperatures in the mid-latitude Pacific Ocean. Positive cycles of the PDO are marked by warmer sea surface temperatures.

Over the past six months, cooler-than-normal water has extended from northern Japan to just east of the dateline, carving out the center of the Blob. But Thoman says the unusual warmth extends well below the surface, leaving the possibility that warmer surface temperatures could reemerge even as the blob clears.

“That warmth is not just skin deep. It extends down through hundreds of meters of ocean water,” Thoman says. “And what that means is given the appropriate atmospheric conditions it’s entirely possible that we could see those warm sea surface temperatures reemerge.”

While the defined center of the Blob is dissipating, Alaska’s southern coastal regions remain warm. This could be the result of remnants of the Blob or the influence of the positive PDO cycle. The question is, what does this mean for Alaska?

“The upshot of that for Alaska,” says Thoman. “With the Blob? It was warm near the Alaska coast. With a positive PDO, it’s warm near the Alaska coast. At the surface the shape has changed but for Alaska the results are similar.”

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