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Hurricane Season 2009: Gabrielle (Southern Indian Ocean)
Mar. 04, 2009

AIRS image of Gabrielle on March 4, 2009> Click for larger image
Credit: NASA JPL, Ed Olsen
Cooler Waters and Wind Shear Now Weakening Gabrielle

Tropical Cyclone Gabrielle hasn't had much of a lifetime in the waters of the Southern Indian Ocean, and winds and cooler water temperatures are cutting it shorter.

On March 4 at 6:00 Zulu Time (1 a.m. EST), Gabrielle had already started running into cooler waters and increased vertical wind shear (winds blowing at different directions at different levels of the atmosphere that weaken or tear a storm apart). Her maximum sustained winds were down to 30 knots (34 mph).

She was in open waters, located near 16.0 degrees south latitude and 104.9 degrees east longitude, moving south-southwestward near 15 knots (17 mph).

The Gabrielle is moving southwestward along the northwestern edge of a strengthening Low to mid-level subtropical ridge (area of high pressure), towards cooler waters and increased wind shear. The Joint Typhoon Warning Center said that they expect Gabrielle to dissipate as a significant tropical cyclone over the open waters of the Southern Indian Ocean in a day or two.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured an infrared image of Gabrielle on Mar. 3 at 18:11 Zulu Time (1:11 p.m. EST).

The infrared image clearly shows a large temperature difference between Gabrielle's cloud tops and the warm ocean temperatures. In this image, the orange temperatures are 80F (300 degrees Kelvin) or warmer. Because Gabrielle is moving southwestward, notice that the ocean temperatures go from dark orange to light orange then yellow in that direction, indicating cooler sea surface waters.

Gabrielle'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.

Text credit: Rob Gutro/NASA Goddard Space Flight Center

Mar. 3, 2009

Tropical Cyclone Gabrielle No Threat to Land

AIRS image of cyclone Gabrielle > Larger image The Southern Indian Ocean has spawned another tropical cyclone. This one is named Gabrielle, or 17S, for the seventeenth tropical cyclone in that ocean basin.

At 15:00 Zulu Time (10 a.m. EST), Tropical Cyclone Gabrielle had sustained winds near 35 knots (40 mph) and was moving southeast near 5 knots (6 mph). She was located in the open waters of the Southern Indian Ocean, near 14.4 degrees south latitude and 106.5 degrees east longitude. The storm is generating wave heights as much as 14 feet.

NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured this visible image of Gabrielle on Mar. 2 at 6:41 UTC (1:41 a.m. EST) as it was in open waters. Hina's center is the circular area of clouds in the center of this satellite image.

Gabrielle is expected to slowly intensify as it veers southeast, then southwest.

Text credit: Rob Gutro/NASA Goddard Space Flight Center