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Hurricane Season 2010: Tropical Storm Edzani (Southern Indian Ocean)
01.15.10
 
January 15, 2010

TRMM's analysis of rainfall within Edzani showed areas of light to moderate rainfall to the south of Edzani's center. > View larger image
TRMM's analysis of rainfall within Edzani on Jan. 14 showed areas of light to moderate rainfall all confined to the south of Edzani's center. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour.
Credit: NASA/SSAI, Hal Pierce
Extra-Tropical Storm Edzani Zipping into History

Tropical cyclone Edzani made its transition into an extra-tropical storm today, January 15, and is fading as it continues racing farther south in the Southern Indian Ocean.

The Joint Typhoon Warning Center issued their final warning on the system last night at 2100 UTC (4 p.m. ET) when it was located about 1,265 miles southeast of La Reunion Island, near 36.4 degrees South latitude and 72.2 degrees East longitude. Edzani had maximum sustained winds near 40 mph (35 knots) and was zipping along at 31 mph in a southeasterly direction over open waters.

The chapter on Edzani will be closed over the coming weekend.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center





January 14, 2010

TRMM's analysis of rainfall within Edzani showed areas of light to moderate rainfall to the south of Edzani's center. > View larger image
TRMM's analysis of rainfall within Edzani on Jan. 14 showed areas of light to moderate rainfall all confined to the south of Edzani's center. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour.
Credit: NASA/SSAI, Hal Pierce
NASA Satellites Take Edzani's Temperature and Rainfall as it Changes

NASA satellite imagery reveals that Tropical Storm Edzani has been taking its time in making the switch from a tropical storm to an extra-tropical storm. Its transition from a warm-core storm to a cold-core system is in its second day, a little longer than originally anticipated. An instrument on NASA's Aqua satellite has noticed that the storm's core is still "warm."

As NASA's Aqua satellite passed overhead today at 0001 UTC (7:01 p.m. ET, Jan. 13) the Advanced Microwave Sounding Unit (AMSU-A) instrument found a warm core temperature anomaly aloft. That means that Edzani had still not made the transition into an extra-tropical storm. AMSU-A is a 15-channel microwave sounder designed primarily to obtain temperature profiles in the upper atmosphere (especially the stratosphere) and to provide a cloud-filtering capability for tropospheric temperature observation. AMSU-A data helped forecasters see that Edzani's core is cooling, and falling, indicating the onset of extra-tropical transition.

A conversion to "extratropical" status means that the area of low pressure (known as Edzani) 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.

NASA's Tropical Rainfall Measuring Mission or TRMM satellite has also watched Edzani during its transition and noticed its heavier rains remain to the south of its center.

Tropical Storm Edzani has maximum sustained winds near 46 mph (40 knots). At 1 a.m. ET (0600 UTC) today, January 14, the storm's center was located approximately 980 nm southeast of La Reunion Island, near 33.9 degrees South latitude and 68.1 degrees East longitude. It was moving south-southeastward at 14 mph (12 knots).

TRMM, managed by NASA and the Japanese Space Agency (JAXA) passed over Tropical Storm Edzani today, January 14 at 2:34 a.m. ET (0734 UTC) and showed that the heaviest rainfall, which was light to moderate, was confined to the south of Edzani's center. Rain was falling there between .78 to 1.57 inches per hour, while other areas around Edzani had light rain.

Rain rates are created from different instruments aboard TRMM. The rain rates in the center of TRMM images are derived from the TRMM Precipitation Radar, the only space borne radar of its kind, while those in the outer portion are from the TRMM Microwave Imager. The rain rates are then overlaid on infrared data from the TRMM Visible Infrared Scanner to create the entire image. The images are created at NASA's Goddard Space Flight Center in Greenbelt, Md.

TRMM also has the ability to analyze how high the thunderstorms are in tropical cyclones, and this morning's image indicated that the highest clouds were around five miles (eight kilometers) high. When thunderstorms in a tropical cyclone are powerful, they can get higher than nine miles (15 km) high. The lower cloud heights are an indication of a weaker storm.

Edzani is expected to be fully extra-tropical sometime tomorrow.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



January 13, 2010

TRMM captured Edzani's rainfall at 12:14 a.m. ET on January 13. > View larger image
TRMM captured Edzani's rainfall at 12:14 a.m. ET on January 13. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour, and are all located to the south and southeast of the storm's center.
Credit: NASA/SSAI, Hal Pierce
NASA Satellite Sees Edzani Becoming Extra-Tropical

Tropical Storm Edzani will soon be Extra-tropical Storm Edzani and NASA's Tropical Rainfall Measuring Mission or TRMM satellite noticed that as its changing, the storm's rains are all south of the system. Earlier today, January 13, Tropical cyclone Edzani was located approximately 785 nautical miles east-southeast of La Reunion Island in the Southern Indian Ocean, near 28.1 South and 68.0 East. Edzani had maximum sustained winds near 40 mph, so it is still hanging onto tropical storm status as it continues changing into an extra-tropical storm. Edzani has tracked southwestward at 14 mph (13 knots) over the past six hours.

Animated infrared satellite imagery confirms what NASA and the Japanese Space Agency's TRMM satellite shows in Edzani – that the deepest convection and heaviest rainfall are confined to the southeast part of the storm. Both types of satellite images also show a fully exposed low-level circulation center. In addition, the latest image from the TRMM satellite shows that Edzani's shape resembles an egg more than a tire indicating that the storm is elongating and weakening.

TRMM captured Edzani's rainfall at 12:14 a.m. ET on January 13 and noticed that all of the rainfall in the storm is in the southern portion of the storm, falling at between .78 to 1.57 inches per hour. For more information about TRMM, visit: http://trmm.gsfc.nasa.gov/.

Edzani is elongating because it's being affected by strong westerly winds. At the same time, cold air stratocumulus clouds are moving into the center of circulation helping it change to extra-tropical status (where the warm core air is replaced by cold air in the core of the storm).

Edzani is expected to continue transitioning into an extra-tropical storm and re-curve to the southeast in the next day, staying safely away from land areas.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



January 12, 2010

TRMM analysis showed that the western side of the storm's circulation is open, and no convection is happening. > View larger image
NASA's TRMM satellite showed Edzani's eastern side still had some areas of heavy rainfall (red) at ~2 inches/hr. Most of the rainfall was east of the center and was between .7 and 1.6 inches/hr (light green). The TRMM analysis also showed that the western side of the storm's circulation is open, and no convection is happening.
Credit: NASA/SSAI, Hal Pierce
NASA Satellite Sees Rainfall in Ebbing Edzani

NASA's Tropical Rainfall Measuring Mission satellite captured a clear picture of what's happening within Tropical Storm Edzani, including where the rainfall is happening and where the center of the storm has been breached. Edzani is fading and will continue to fade over the next couple of days.

Also known as TRMM, the Tropical Rainfall Measuring Mission satellite is managed by NASA and the Japanese Space Agency, JAXA and the satellite acts like a rain gauge in space by measuring rainfall of storms on Earth from its orbit.

The TRMM satellite passed over Edzani on January 11 at 12:27 a.m. ET (0527 UTC), and noticed that the storm's highest thunderstorm cloud tops had dropped to about 6 miles (10 kilometers), indicating that convection (rapidly rising air that forms thunderstorms) is waning. Stronger convection creates higher, more powerful thunderstorms, but Edzani's is weakening.

The TRMM rainfall analysis revealed that the eastern side of the storm still had areas of heavy rainfall, falling at about 2 inches per hour. However, most of the rainfall was to the east of the center of circulation, and was between .7 and 1.6 inches per hour. The TRMM analysis also showed that the western side of the storm's circulation is open, and there is no convection happening.

The Joint Typhoon Warning Center, the agency that monitors and forecasts tropical cyclones in the Indian Ocean, issued their final warning on Edzani earlier today, January 12, but noted that they will continue to watch Edzani for possible regeneration. The JTWC confirmed what TRMM satellite imagery showed, "Central convection has completely eroded over the past 12 hours with some weak convection remaining along the southern quadrant within the warm frontal zone."

Animated multispectral satellite imagery showed that a weak front with cold-air stratocumulus clouds are wrapping around the western edge of Edzani. It appears that Edzani is also transitioning into an extra-tropical storm.

At 0000 UTC today (or 7 p.m. ET on January 11), Edzani's last position was approximately 975 nautical miles east-southeast of La Reunion island, near 26.1 degrees South Latitude and 72.5 East Longitude. Edzani had maximum sustained winds near 46 mph (40 knots) and it was moving west-southwest near 6 mph (5 knots). Despite the weakening of the storm and transitioning to an extra-tropical storm, Edzani is also moving back over warmer waters, so forecasters will keep a close eye on it for possible regeneration.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



January 11, 2010

The purple area indicates strong convection and high thunderstorms with cloud tops colder than -63F. > View larger image
This infrared image from NASA's Aqua satellite shows Edzani as a tight round storm, in the Southern Indian Ocean on January 8 at 19:53 UTC. The purple area indicates strong convection and high thunderstorms with cloud tops colder than -63F. Since then, convection has waned and the storm started falling apart.
Credit: NASA JPL, Ed Olsen
Still Safely at Sea, Edzani Now a Tropical Storm

The weekend wasn't very helpful to Edzani, once a powerful Cyclone, now weakened to a tropical storm in the Southern Indian Ocean. That's because of cooler waters and increased wind shear.

On Monday, January 11 at 10 a.m. ET (1500 UTC) Edzani's maximum sustained winds were near 52 mph (45 knots). Edzani's center was about 970 nautical miles east-southeast of La Reunion island, near 26.0 South and 72.3 East. Edzani was moving south-southeast near 13 mph, but the storm is expected to turn to the southwest in the next day. It will still remain in open waters and poses no threat to land.

When NASA's Aqua satellite flew over Edzani on Friday, January 8, it was still a tropical cyclone. Over the weekend it hit cooler waters and windshear which have really weakened the storm. On January 8, infrared satellite imagery from the Atmospheric Infrared Sounder (AIRS) instrument on Aqua showed Edzani as a tight rounded storm. Since then, it has lost its "roundness" and has become somewhat asymmetrical.

Satellite data has revealed that Edzani's low level center of circulation has become exposed, and that it's convection, which is now confined to the eastern half of the system is decreasing. Both of those factors indicate a weakening storm. Another thing tearing at the storm is vertical wind shear, which has increased over the last 12 hours.

Forecasters now expect Edzani to continue weakening further and dissipate by mid-week.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



January 08, 2010

AIRS image of Edzani > View larger image
NASA's Aqua satellite AIRS instrument captured a visible image of the western half of Edzani's clouds on January 8 at 0905 UTC (4:05 a.m. ET) as it flew overhead. Edzani's eye is still visible. The bright spot to the left of Edzani is sun glint off the ocean surface.
Credit: NASA JPL, Ed Olsen
Super Cyclone Edzani Staying Safely at Sea Spawning Super Swells

It's a good thing that Cyclone Edzani is far away from land and will stay that way this weekend, because it's a powerful cyclone. In fact it’s a Category 4 cyclone on the Saffir-Simpson scale generating waves almost as tall as a three-story building!

On January 8 at 10 a.m. ET (1500 UTC), Cyclone Edzani had maximum sustained winds near 155 mph! That's 135 knots or 250 kilometers per hour, and it has higher gusts. Edzani's powerful hurricane-force winds extend out 40 miles from its center, while tropical storm-force winds extend up to 130 miles from the center.

Edzani was centered about 590 nautical miles south-southeast of Diego Garcia near 16.2 degrees South latitude and 76.7 degrees East longitude, safely away from any land areas. Edzani was moving southwestward near 9 mph (8 knots/14 km/hr).

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured a visible image of the western half of Edzani's clouds early today, January 8 at 0905 UTC (4:05 a.m. ET) as it flew overhead. Edzani's eye was visible in the image, and forecasters at the Joint Typhoon Warning Center confirmed that the eye was 15 nautical miles in diameter using infrared and microwave imagery, such as that also provided by AIRS. It's a powerful storm that is generating waves up to 32 feet high, that's almost three stories high in a building!

If a Category four cyclone (or hurricane) made landfall it would do severe damage. Fortunately, Edzani is going to by-pass land. For those who are curious, however, the Saffir-Simpson Scale says that a Category 4 storm would have: "Sustained winds 131-155 mph (114-135 knots or 210-249 km/hr). Extremely dangerous winds causing devastating damage are expected. Some wall failures with some complete roof structure failures on houses will occur. All signs are blown down. Complete destruction of mobile homes (primarily pre-1994 construction). Extensive damage to doors and windows is likely. Numerous windows in high rise buildings will be dislodged and become airborne. Windborne debris will cause extensive damage and persons struck by the wind-blown debris will be injured or killed. Most trees will be snapped or uprooted. Fallen trees could cut off residential areas for days to weeks. Electricity will be unavailable for weeks after the hurricane passes."

Over the weekend, Edzani will continue moving in a southwesterly direction. By early next week, Edzani will be far southeast of Port Louis and Reunion Island as it continues on its track. By then, Edzani will have entered into cooler waters and will be a weaker storm.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



January 07, 2010

Red areas near Edzani's center are considered heavy rainfall at almost 2 inches per hour. > View larger image
TRMM captured an image of rainfall in Edzani on Jan. 6. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour. Red areas near Edzani's center are considered heavy rainfall at almost 2 inches per hour.
Credit:NASA/SSAI, Hal Pierce
A 3-D look at the cloud heights revealing a towering cloud near 17 km (10.6 miles) high indicating a strong storm. > View larger image
TRMM data provided a 3-D look at the cloud heights; temperature and rainfall in Tropical Storm Edzani, revealing a towering cloud near 17 km (10.6 miles) high indicating a strong storm.
Credit:NASA/SSAI, Hal Pierce
NASA's Aqua satellite captured a visible image where Edzani's eye is now clearly visible. > View larger image
NASA's Aqua satellite captured a visible image of Tropical Cyclone Edzani in the South Indian Ocean on Jan. 7 at 0825 UTC (3:25 ET) and an eye is now clearly visible, indicating that the storm has strengthened.
Credit:NASA MODIS Rapid Response Team
Two NASA Satellites See Edzani Power Up in Clouds and Rainfall

The latest satellite imagery from NASA's Aqua and Tropical Rainfall Measuring Mission satellites have provided forecasters with signs in clouds and rainfall that Edzani is strengthening in the Southern Indian Ocean. Edzani has become a tropical cyclone as a result of low wind shear and warm ocean temperatures.

The Tropical Rainfall Measuring Mission or TRMM satellite's main mission is to monitor rainfall in the global tropics but has also proven very useful for checking on the development of tropical cyclones. TRMM's Precipitation Radar instrument is especially valuable for checking the strength of tropical cyclones located far from land based radar stations. The TRMM satellite passed over Tropical Cyclone Edzani in a remote area of the South Indian Ocean on January 6 at 1502 UTC (10:02 a.m. ET).

TRMM rainfall analyses are derived from TRMM's Precipitation Radar (PR) instrument and the TRMM Microwave Imager instrument (TMI). That data is overlaid on an infrared image from TRMM's Visible and Infrared Scanner (VIRS). The Precipitation Radar analysis revealed that the tropical cyclone has strengthened to at least tropical storm strength with very heavy thunderstorms near Edzani's center of circulation.

Most of the rainfall in Edzani was moderate, between .78 to 1.57 inches per hour. However, northeast of the center where the highest thunderstorms were located, TRMM indicated heavy rainfall at almost 2 inches per hour.

Further development may be likely because TRMM's Precipitation Radar instrument indicates that the powerful thunderstorms near Edzani's center tower to heights above 17 km (~10.6 miles). TRMM is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA) designed to monitor and study tropical rainfall.

Early this morning, January 7, the Moderate Resolution Spectroradiometer instrument aboard NASA's Aqua satellite captured a visible image of Tropical Cyclone Edzani in the South Indian Ocean. The image showed that circulation around the storm has tightened and an eye is now clearly visible, indicating that the storm has strengthened.

Because Edzani continues to be a favorable environment with warm sea surface temperatures over 80 degrees Fahrenheit, and low wind shear, the storm is expected to continue intensifying over the next two days before hitting cooler waters.

On January 7 at 1500 UTC (10 a.m. ET), Edzani's center was about 590 nautical miles southeast of Diego Garcia, near 14.6 degrees South and 79.4 degrees East. Edzani is now a Category XX tropical cyclone on the Saffir-Simpson hurricane scale, because it's maximum sustained winds are near 115 mph (185 km/hr) with higher gusts. Edzani is moving southwestward near 5 mph (7 km/hr).

Edzani continues to intensify and will keep heading west-southwest before a turn to the south, passing far to the east of Mauritius and La Reunion island. By the weekend, Edzani is expected to run into cooler waters, which will weaken the system.

Text credit: Hal Pierce, NASA/SSAI and Rob Gutro, NASA/Goddard Space Flight Center



January 06, 2010

Tropical Storm Edzani on January 6 at 0450UTC safely at sea in the Southern Indian Ocean. > View larger image
The MODIS instrument on NASA's Terra satellite captured this view of Tropical Storm Edzani on January 6 at 0450UTC safely at sea in the Southern Indian Ocean
Credit:NASA MODIS Rapid Response Team
System 098S Strengthens into Tropical Storm Edzani

The area of low pressure that NASA satellites and forecasters were watching yesterday, has taken advantage of low wind shear and warm sea surface temperatures in the Southern Indian Ocean and strengthened into Tropical Storm Edzani today.

Tropical cyclone Edzani, the seventh tropical cyclone (07S) in the southern hemisphere this season, was located about 650 miles east-southeast of Diego Garcia today, January 6 at 10 a.m. ET (1500 UTC). That's near 13.1 degrees South latitude and 81.8 degrees East longitude. Edzani's maximum sustained winds were near 40 mph (35 knots). Edzani was moving west-southwest near 12 mph, and generating waves around 15 feet high.

Multispectral satellite imagery and a microwave satellite image revealed that convection is strengthening and the storm is consolidating. NASA's Terra satellite flew over Tropical Storm Edzani early this morning at 0450UTC (10:20 a.m. local time). The Moderate Resolution Spectroradiometer, or MODIS instrument captured a visible image of the storm that showed the storm has developed a more circular shape.

Edzani will continue to track west-southwestward and gradually intensify over the next couple of days, remaining safely in open ocean.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center



AIRS image of system 98S taken in infrared > View larger image
NASA's Aqua satellite captured cold thunderstorm cloud tops of System 98S in this infrared image January 5, 1:30 p.m. local Time. The high, cold, cloud tops are as cold as -63F and represent strong convection.
Credit: NASA JPL, Ed Olsen
System 98S Has a Good Chance for Development in the Southern Indian Ocean

System 98S is being watched closely by forecasters at the Joint Typhoon Warning Center and NASA satellites. NASA's infrared satellite imagery has confirmed that the storm has been maintaining strong convection (rising air that forms thunderstorms) over the last 18 hours.

The Joint Typhoon Warning Center noted in their forecast today that the "Formation of a significant tropical cyclone is possible within 155 nautical miles either side of a line from 10.1S and 88.0E to 13.2S and 82.9E within the next 12 to 24 hours."

On January 5, winds are estimated to be 25 to 30 knots. The center of 98S's circulation is located near 10.6 South and 87.1 East. The system is moving west-southwestward at 7 mph (6 knots). The center is about 885 nautical miles east-southeast of Diego Garcia.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured an infrared image of System 98S on January 5, 1:30 p.m. local Time. The image showed high, cold, cloud tops are as cold as -63F that represent strong convection.

AIRS image of system 98S taken in visible light> Larger image
This visible image of System 98S on January 5 at 0835 UTC has taken on the rounded shape of a developing low pressure area. Credit: NASA JPL, Ed Olsen
Recent infrared imagery showed that convection has continued over the last 18 hours, while wind shear continues to decrease. Those are two signs that the system may strengthen. Even the waters where the system is currently located and moving toward are favorable for further development, because sea surface temperatures are at or above 80 degrees Fahrenheit.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center