“What a change,” commented David Ornauer of the Star and Stripes Pacific Storm Tracker blog. “What a major, major change.”

The imagery of Noru’s transformation is remarkable. Here is a satellite animation showing it morph from tropical storm to Super Typhoon status (to become a Super Typhoon, a storm’s peak winds must reach at least 150 mph):

From a somewhat ragged swirl, Noru became almost perfectly circular and symmetric — flaunting an unmistakable eye.

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Once it neared and reached peak intensity late Sunday, boasting maximum sustained winds of 160 mph (the equivalent of a Category 5 hurricane) the images were jaw-dropping:

Here’s a close-up inside the eye of Noru, revealing small swirls known as mesovortices:

In the above animation, you can also see the feature known as the “stadium effect” common around the center of monster storms, in which clouds surrounding the eye curve outward with altitude.

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Noru, which meandered in the Pacific for 10 days before it turned into a beast, weakened slightly Monday. The Joint Typhoon Warning Center said its maximum sustained winds had fallen to about 145 mph — the equivalent of a Category 4 hurricane. Slow weakening is forecast over the next 36 hours “as it exhausts most of the energy available from warm water,” the Center said.

The storm is expected to track to the northwest over the next several days, weakening further, but could threaten Japan in about a week. However, models differ significantly on the details of the storm’s course beyond about 72 hours.