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Hurricane Season 2011: Tropical Cyclone Benilde (Southern Indian Ocean)
01.05.12
 
On Jan. 5 at 09:10 UTC (4:10 a.m. EST) Benilde appeared elongated as a result of wind shear. › View larger image
When NASA's Aqua satellite flew over Benilde on Jan. 5 at 09:10 UTC (4:10 a.m. EST) it appeared elongated as a result of wind shear with the strongest convection and most clouds and rain on the southern side of the storm.
Credit: NASA/NRL
Benilde Now a Remnant Low, NASA Sees Bulk of Rainfall South of Center

Wind shear continues to pummel Tropical Cyclone Benilde, and has weakened it to the status of a remnant low pressure area today. NASA's Aqua satellite captured an image of the storm that shows how wind shear has pushed the bulk of its clouds and showers south of the center of circulation.

When NASA's Aqua satellite flew over Tropical Cyclone Benilde on January 5, 2012 at 0910 UTC (4:10 a.m. EST), the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a visible image of the storm. The image showed a weak circulation with a circle of clouds around the storm, but the bulk of clouds and showers were confined to the southern quadrant of the storm, as a result of northerly wind shear.

At that time, Benilde's maximum sustained winds were down to 25 knots (29 mph/46 kmh) and its minimum central pressure was 1004 millibars. Benilde was located near 24.2 South latitude and 75.0 East longitude, in the open waters of the Southern Indian Ocean. Wind shear continues to pummel Benilde and the remnant low is expected to weaken more over the open ocean.

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



Jan. 4, 2012

On Jan. 4, Benilde appeared elongated as a result of wind shear. › View larger image
When NASA's Aqua satellite flew over Benilde on Jan. 4 at 08:28 UTC (3:28 a.m. EST) its circulation was still evident, but it appeared elongated as a result of wind shear.
Credit: NASA/NRL
NASA Satellite Sees Tropical Storm Benilde Stretched By Windshear

Wind shear can a bad thing for a tropical cyclone trying to keep itself together, and that's what tropical storm Benilde is experiencing today. NASA satellite imagery confirm that Benilde is stretched out and less organized today than it was yesterday.

Vertical wind shear, or the change of winds with height, interacts with the thunderstorms that make up a tropical cyclone to either enhance or diminish the strength of the vertical updrafts. Updrafts can build a thunderstorm up and help it reach the top of the troposphere, in which case it would be very strong. For example, winds in the middle of the troposphere can be blowing in one direction at a given speed, while surface winds can be blowing in another direction. That kind of vertical wind shear can destroy all but the strongest storms by blowing the updraft away from its thunderstorm base.

On January 4, 2012 at 0600 UTC (1 a.m. EST), Tropical Storm Benilde's maximum sustained winds were near 35 knots (40 mph/65 kmh) making it a minimal tropical storm. It was located about 870 nautical miles south of Diego Garcia near 21.9 South latitude and 74.7 East longitude. Benilde was moving east-southeast at 10 knots (~12 mph/~19 kmh).

When NASA's Aqua satellite flew over Benilde on Jan. 4 at 08:28 UTC (3:28 a.m. EST) its circulation was still evident, but it appeared elongated as a result of wind shear. The low-level circulation center of the storm was fully-exposed to the strong vertical westerly wind shear blowing at 40 knots (46 mph/74 kmh). The wind shear has continued to weaken the tropical storm and stretch it out, pushing the rainfall about 205 nautical miles to the south-southeast of the center. The NASA Aqua image, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the satellite, showed that the bulk of the cloud cover is in the south-southeastern quadrant where the rains are located.

The strong wind shear, coupled with the cooler waters (around 25 degrees Celsius/77 Fahrenheit) that Benilde has moved into are expected to weaken the storm into a remnant low pressure system.

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



Jan. 3, 2012

NASA › Larger image
Two visible images of Tropical Cyclone Benilde in the south Indian Ocean were captured by NASA satellites on Dec. 30 (left) and Dec. 31, 2011 (right).
Credit: NASA Goddard LANCE/EOSDIS MODIS Rapid Response Team
NASA "Eyes" Tropical Storm Benilde Twice Over

Two NASA satellites "eyed" the eye of Tropical Storm Benilde over two days as it spun in the southern Indian Ocean. NASA's Aqua and Terra satellites captured images on Dec. 30 and 31, 2011 that showed a more well-defined eye on the second day. Benilde continues to spin over open ocean today and remains far from land.

Tropical Storm Benilde formed over the southern Indian Ocean on December 28, 2011. On December 30, the U.S. Navy’s Joint Typhoon Warning Center (JTWC) reported that Benilde, now a cyclone, was located roughly 545 nautical miles (1,010 kilometers) southeast of Diego Garcia. Benilde had maximum sustained winds of 50 knots (95 kilometers per hour) with gusts up to 65 knots (120 kilometers per hour (kmh)).

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured this natural-color image on December 30, 2011. In that image, Benilde sported both a distinct eye and spiral shape characteristic of strong storms. The MODIS image on NASA's Aqua satellite captured another image of Benilde the next day, December 31, 2011. That image showed a more defined eye.

Today, January 3, 2012, Benilde is still spinning through the southern Indian Ocean and remains far from land. Maximum sustained winds are near 55 knots (63 mph/102 kmh). Benilde is located near 21.7 South and 72.9 East. That's about 840 nautical miles south of Diego Garcia. Benilde is moving to the south at 3 knots (3.4 mph/5.5 kmh). Moderate westerly wind shear is taking a toll on the cyclone, especially in the bands of thunderstorms north of the center of circulation. The bands of thunderstorms to the south of the center appear stronger and more organized.

The Joint Typhoon Warning Center noted that the remnant moisture from former low pressure System 98S is now feeding into Tropical Cyclone Benilde. Although that is adding to the cyclone, Benilde is headed toward cooler waters and increased wind shear both of which are expected to weaken the cyclone in the coming days.

Text Credit: Rob Gutro/Michon Scott
NASA's Goddard Space Flight Center, Greenbelt, Md.
NASA Earth Observatory



Dec. 30, 2011

TRMM image of Tropical Cyclone Benilde› Larger image
This image of rainfall within Tropical Storm Benilde was captured by the TRMM satellite on Dec. 30 at 0916 UTC (4:16 a.m. EST). Heaviest rainfall was occurring near the center at a rate of 1.0 to 1.4 inches per hour. The TRMM rainfall rates were overlaid on visible image from the METEO-7 satellite. Credit: NRL/NASA
Tropical Cyclone Benilde Forms in the Southern Indian Ocean

NASA's Aqua satellite passed over Cyclone Thane just after its center made landfall in eastern India, south of Chennai.

The fourth southern Indian Ocean tropical cyclone formed today over 500 miles from land. NASA's TRMM satellite saw moderate rainfall occurring around the center of Tropical Storm Benilde.

Tropical Cyclone Benilde is located about 545 nautical miles southeast of the island of Diego Garcia near 13.4 South and 79.0 East. Diego Garcia is a tropical, footprint-shaped coral atoll located south of the equator. On Dec. 30, Benilde had maximum sustained winds near 50 knots (57 mph/92 kmh) and is moving westward at 15 knots (17 mph/28 kmh).

The TRMM satellite measured rainfall rates within Tropical Storm Benilde on Dec. 30 at 0916 UTC (4:16 a.m. EST). Heaviest rainfall was occurring near the center at a rate of 1.0 to 1.4 inches (25 to 35 millimeters) per hour.

Satellite imagery shows thunderstorms banding around the center, a sign of organization. Benilde is in an area of moderate vertical wind shear.

Benilde is expected to move in more of a west-southwesterly direction, staying at sea over the next several days.

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