NASA - National Aeronautics and Space Administration

Feb. 24, 2009

Hina Hits a Hard Time

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Tropical Cyclone Hina is dissipating in the southern Indian Ocean because the storm has run into adverse atmospheric conditions.

Credit: NASA JPL, Ed Olsen Wind shear is one factor that can make or break a tropical cyclone, and that's what's happening to Hina. Wind shear occurs when winds at different levels of the atmosphere blowing in different directions weaken a storm. Upper level winds can also shear the top off of a storm, making it fizzle out.

On February 24, the Joint Typhoon Warning Center issued their final advisory on Hina as the storm's winds dropped from 45 knots (51 mph) to 35 knots (40 mph) and are expected to continue fading because of wind shear.

Hina's final location was about 770 miles south-southeast of Diego Garcia. That's near 197 degrees south latitude and 6.4 degrees east longitude.

NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured this visible image of Hina on Feb. 24 at 8:53 UTC (3:53 a.m. EST) as it was rapidly fading away in open waters. Hina's center is the circular area of clouds in the center of this satellite image. Hina is expected to fizzle in the next day or two.

Text credit: Rob Gutro/NASA Goddard Space Flight Center

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Feb. 23, 2009

New Cyclone Hina Looks and Zips Like a Comet

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Credit: NASA/JPL, Ed Olsen If you want to see a "comet in the clouds" take a look at the visible satellite imagery of Cyclone Hina. The sixteenth tropical cyclone was born in the southwestern Pacific Ocean on Saturday, Feb. 21 about 530 miles southeast of the Diego Garcia. After two days it became Tropical Cyclone Hina, moved over 250 miles!

On Monday, February 23, 2009, Hina had reached its peak intensity with sustained winds near 60 knots (69 mph) according to forecasters at the Joint Typhoon Warning Center. At 900 UTC (4 a.m. EST), Hina was moving only now near 6 knots (7 mph), but it covered a lot of ground since Sat. Feb. 21. Hina is now located about 785 miles south-southeast of Diego Garcia. That's near 19.2 degrees south latitude and 78.2 degrees east longitude. Tropical Storm-force winds of 34 knots (40 mph) and higher extending as far as 90 miles out from the center of the storm.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured a visible and infrared image of Hina on Feb. 23 at 08:11 Zulu Time (3:11 a.m. EST).

"The visible image makes Hina look like a comet," said Edward Olsen, of the AIRS Team at NASA's Jet Propulsion Laboratory, Pasadena, Calif. Hina has a trail of clouds extending from it, resembling a comet's tail.

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Credit: NASA JPL, Ed Olsen The infrared image clearly shows a large temperature difference between Hina's cloudtops and the warm ocean temperatures. In this image, the orange temperatures are 80F (300 degrees Kelvin) or warmer. Hina's lowest temperatures (in purple) are associated with high, cold cloud tops. Those temperatures are as cold as or colder than 220 degrees Kelvin or minus 63 degrees Fahrenheit (F). The blue areas are around 240 degrees Kelvin, or minus 27F.

AIRS generates infrared, microwave and visible images. The AIRS infrared data creates an accurate 3-D map of atmospheric temperature, water vapor and clouds, all of which are helpful to forecasters.

Hina is expected to slowly weaken as it enters unfavorable atmospheric conditions. It is expected to on a more southerly to southwesterly track over the next few days before dissipating.

Text credit: Rob Gutro/NASA Goddard Space Flight Center