Hurricane Season 2011: Tropical Depression Noru (Western North Pacific Ocean)

NASA sees Tropical Depression Noru Transitioning, Heading North

Infrared satellite imagery from NASA's Aqua satellite late yesterday revealed that Tropical Depression Noru is losing strength while transitioning into an extra-tropical storm in the western North Pacific Ocean. High pressure is pushing Noru northward into the Sea of Okhotsk.

The Sea of Okhotsk covers 611,000 square miles, and borders eastern Russia. It is northwest of the Sea of Japan, where Tropical Depression Noru is currently tracking through, and will likely be Noru's final resting place.

When Aqua passed over Tropical Storm Noru the Atmospheric Infrared Sounder (AIRS) instrument noticed warmer cloud top temperatures that the day before, indicating that the strength of the rapidly rising air that forms the thunderstorms within, was waning. On Sept. 5 at 10:53 p.m. EDT, the strongest thunderstorms in Noru were southeast of its center.

By Sept. 6 at 8 a.m. EDT, Noru's maximum sustained winds were near 30 knots (35 mph). It was located 425 nautical miles east of Misawa Air Base, Japan near 41.3N and 150.6E. It is moving to the north at 19 knots.

As Noru continues north, the sea surface temperatures are not warm enough to support a tropical cyclone, which is a "warm core system," so the inner core cools and becomes a cold core system which makes it extra-tropical. Over the next couple of days, Noru will continue its journey into the Sea of Okhotsk off the coast of Russia.

Text credit: Rob Gutro, NASA's Goddard Space Flight Center, Greenbelt, Md.