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Hurricane Season 2009: Ken (Southern Pacific Ocean)
03.20.09
 
Mar. 20, 2009

AIRS image of Ken on March 19, 2009> Click for larger image
Credit: NASA/JPL, Ed Olsen
Ken Knocked Out of "Tropical Storm" Status

What was once Tropical Storm Ken in the southwestern Pacific Ocean is now extra-tropical Ken, and the storm is fizzling.

On Mar. 19, Ken was last reported 265 miles south of the island or Rarotonga, but has since tracked further southeast of that location, deeper into the open waters of the southwestern Pacific Ocean. Ken's remnants will continue to fade in the open waters.

NASA's Aqua satellite flew over Ken and the Atmospheric Infrared Sounder (AIRS) instrument onboard captured an infrared image of his cloud temperatures on Mar. 19 at 11:41 UTC (7:41 a.m. EDT). Very cold cloud temperatures indicate high thunderclouds. The less cold the temperatures appear on the satellite image, the lower the clouds are, indicating that they are less powerful. This image was taken when Ken was transitioning into an extra-tropical storm and cloud temperatures were a lot less cold than they were the day before.

Ken will be just a record in the tropical history books for 2009 by the end of the weekend of March 21-22.

Text credit: Rob Gutro/NASA Goddard Space Flight Center


Mar. 19, 2009

Ken Becoming Extra-Tropical

AIRS image of Ken> Click for larger image
Credit: NASA JPL, Ed Olsen
When is a tropical storm not a tropical storm? The answer is when it becomes "extra-tropical." That's what Tropical Storm Ken is becoming in the open waters of the South Pacific Ocean.

What Does "Conversion to an Extratropical Storm" Mean?

A conversion to "extratropical" status means that the area of low pressure (known as Ken in this case) eventually loses its warm core and becomes a cold-core system. During the time it is becoming extratropical the cyclone's primary energy source changes from the release of latent heat from condensation (from thunderstorms near the storm's center) to baroclinic (temperature and air pressure) processes. When a cyclone becomes extratropical it will usually connect with nearby fronts and or troughs (extended areas of low pressure) consistent with a baroclinic (pressure) system. When that happens it appears the system grows larger while the core weakens.

The Joint Typhoon Warning Center noted "Satellite imagery shows that a front-like line has formed on the north to northeast quadrant of the system. Environmental analysis indicates that Ken is rapidly approaching the baroclinic zone, characterized by increasing vertical wind shear and cold air advection (cold air moving into the core of the storm, as noted above)."

On Mar. 19 at 03:00 Zulu Time (Mar. 18 at 11 p.m. EDT), Ken still had sustained winds near 45 knots (52 mph), but those winds are expected to drop to 35 knots (40 mph) in 24 hours. Ken was located about 265 nautical miles south of the island of Rarotonga, near 26.3 south and 159.6 west. It was moving southeastward near 12 knots (14 mph). Rarotonga is the most populous island in a group of islands known as the Cook Islands.

NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured this visible image of Ken on Mar. 19 as it was becoming extratropical. The cyclone is expected to fully transition into an extra-tropical system within the next 24 hours.

Text credit: Rob Gutro/NASA Goddard Space Flight Center


Mar. 17, 2009

AIRS image of Tropical Storm Ken> Click for larger image
Credit: NASA JPL, Ed Olsen
Ken: An Irish Named Storm for St. Patrick's Day

Saint Patrick's Day marked the formation of a new tropical storm in the waters of the southwestern Pacific Ocean, with a good Irish name: Ken (short for Kenneth). Ken may be "green" now because he just formed, but he's forecast to grow up fast, as he's moving into good atmospheric and oceanic conditions that will help him strengthen.

Ken is also known as tropical cyclone 21P. On March 17 at 15:00 Zulu Time (11:00 a.m. EDT), Ken was located near 22.2 degrees south latitude and 162.6 degrees east longitude. That's about 170 nautical miles west-southwest of the island of Rarotonga. Ken currently has sustained winds near 35 knots (40 mph) and is moving south-southeast near 6 knots (7 mph). Currently, he's not threatening any landmasses, so residents in the southwestern Pacific Ocean will have the "Luck of the Irish" today.

NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured this visible image of Ken on Mar. 17 at 00:59 UTC (9:59 p.m. EDT, Mar. 16) right after he formed. Ken is the swirl of clouds on the right side of this satellite image.

It appears that Ken's luck will hold, as he moves into an area considered a "pot of gold" for tropical storms: warm sea surface temperatures and light wind shear (winds that can tear a storm apart). That means that Ken is expected to strengthen over the next two days, and that's no "blarney."

Text credit: Rob Gutro/NASA Goddard Space Flight Center