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Hurricane Season 2009: Jade (Southern Indian Ocean)
April 10, 2009

Jade Making the "Extra-Tropical" Switch Over the Weekend

satellite of storm Jade Credit: NASA
> Larger image
Tropical Storm Jade has had an interesting life. It was born off the northeastern coast of Madagascar last weekend, strengthened into a Category 1 cyclone and traveled from north to south over the island nation where it weakened to a low pressure area. On Thursday, Apr. 8, it was "re-born" into a tropical storm and is now transitioning into an extra-tropical storm.

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

Although Jade is in the open waters of the Southern Indian Ocean and not a threat to land, it made its mark during its trek through Madagascar. Now that reports have come in, according to Agence France-Presse, more than 3,300 people are homeless and at least eight people died due to the heavy flooding rains from the storm.

Jade is moving much faster than it was yesterday and traveling southeast. It is now speeding along at 15 knots (17 mph), quite an increase from yesterday's 3 knots (3 mph). On Friday, Apr. 10, Jade was located 280 nautical miles south of La Reunion Island, near 25.5 south and 53.1 east.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite passed over Tropical Storm Jade at 10:05 UTC (6:05 a.m. EDT) on Apr. 10, and its data was used to create a full-color image. Madagascar is seen on the left side of the image, and Tropical Storm Jade is in the bottom center.

Jade was still packing sustained winds near 35 knots (40 mph). Forecast models indicate that Jade's center will become absorbed into a trough (an elongated area of low pressure), and it will intensify and make the transition into an extra-tropical storm over the weekend.

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

April 09, 2009

AMSR-E image of Jade> Click for larger image
Credit: NRL/NASA
NASA's AMSR-E Sees Jade Slowly "Hopping" Despite Wind Shear

Tropical Cyclone Jade was reborn yesterday, April 8, and is slowly "hopping" east-southeastward in the open waters of the Southern Indian Ocean. It will gradually turn south. Wind shear has been tearing the storm down, but rainfall continues to happen on the southern side of the storm as a sign that the storm is still thriving.

Wind shear means that winds blowing at different levels of that atmosphere are tearing the storm apart. Picture a tropical cyclone as a large stack of hay. Wind shear would come from people on ladders at different heights and directions holding powerful fans directed into the haystack. The hay (or thunderstorms that make up a tropical cyclone) is blown apart. In tropical storms, the thunderstorms can't develop as well as they would without the wind shear, and the overall storm weakens.

NASA's Aqua satellite passed near Jade on Apr. 9 at 10:59 UTC (4:59 a.m. EDT) and captured an image of the storm its Advanced Microwave Scanning Radiometer-E (AMSR-E) instrument. The satellite passed over the western edge of Tropical Cyclone Jade, which is the part of the storm that is visible in this image. Madagascar is visible to the left of the storm. The grey portion of the image to the right, was out of the satellite's view.

At that time, Jade had sustained winds near 30 knots (34 mph) and the storm's pressure was 1000 millibars. Jade was located near 22.6 degrees south latitude and 50.2 degrees east longitude, about 301 nautical miles west-southwest of La Reunion Island and no threat to land. It was slowly hopping east-southeast near 3 knots (3 mph) through the open ocean.

Data from AMSR-E provides measurements of precipitation rate, cloud water, water vapor, sea surface winds, and sea surface temperature, all of which are indicators in whether a tropical cyclone is strengthening or weakening. One unique aspect of AMSR-E sea surface temperature data is that it reads those surface temperatures through most types of cloud cover, supplementing infrared-based measurements that are restricted to cloud-free areas.

Forecasters at the U.S. Navy's Joint Typhoon Warning Center expect that Jade will re-intensify as it transitions into an extra-tropical storm in the next day and a half and will be watching it. Fortunately, Jade is nowhere near landmasses now.

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

April 08, 2009

AIRS image of Jade> Click for larger image
Credit:: NASA JPL, Ed Olsen
Cyclone Jade is Resurrected on Easter Week

Easter week seems like an appropriate time to talk about a resurrection, and the low pressure area over Madagascar that was once Cyclone Jade has moved over open waters, strengthened and has been re-born into a tropical storm.

Satellite imagery from various NASA and other satellites show Jade's center has moved off the coast of Madagascar, back into warm open waters. Sea surface temperatures of at least 80 degrees Fahrenheit and very weak wind shear (if strong, they're winds that can tear a storm apart) are needed to re-energize a tropical cyclone, and that's what happened with Jade.

Because Jade is back in action, the U.S. Navy's Joint Typhoon Warning Center started issuing storm bulletins again. On April 8 at 15:00 UTC (11 a.m. EDT), Jade was located 350 miles west of La Reunion Island, and its center was just east of the southeast Madagascar coastline. Tropical storm force winds of 34 knots (39 mph) are blowing up to 85 miles from Jade's center. Those winds are still creating 14 foot-high wave heights.

Jade was carrying maximum sustained winds near 40 knots (46 mph) and was moving south-southeast near 4 knots (5 mph). Although the conditions off the Madagascar coast have enabled Jade to strengthen, forecasters at the Joint Typhoon Warning Center expect the storm to run into "hostile atmospheric conditions some 48 hours from now, leading to its dissipation."

NASA's Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured this infrared image on April 8 at 10:11 UTC (6:11 a.m. EDT). Jade is the round area in blue and purple located in the center of this image. The image shows that Jade's western-most clouds extend over extreme southeastern Madagascar.

The infrared image shows the large temperature difference between Jade's cloud-tops and the warm ocean temperatures. In this image, the orange temperatures are 80F or warmer. Jade's lowest temperatures (in purple) are associated with high, cold cloud tops. Those temperatures are as cold as or colder than minus 63 degrees Fahrenheit (F). The blue areas are around minus 27F.

Bulletins of Jade's progress will likely continue again for the next 48 hours until the storm once again starts fading.

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

April 07, 2009

Jade Now a Low Pressure Area, Soaking Inland Madagascar

TRMM image of Tropical Cyclone Jade on 4/6/09 Credit: NASA/SSAI, Hal Pierce
> Larger image
Former Tropical Cyclone Jade is now an area of low pressure over southeastern Madagascar, and a NASA satellite captured its soaking rains. Jade is trudging southward over the length of mainland Madagascar and keeping the east coast and central areas wet and windy.

Jade made landfall in the northeast corner of the island of Madagascar, and is moving south over the island, almost paralleling the coast.

Satellite imagery has indicated that Jade's center is tracking further inland over rough terrain, and that's causing it to weaken more quickly. Jade is expected to fade by April 8 although it will be watched for re-generation when the low slides off the coast.

On April 6 at 1800 UTC (2 p.m. EDT), the U.S. Navy's Joint Typhoon Warning Center issued its final advisory on Jade. At that time, Jade was located near 17.3 degrees south latitude and 49.0 degrees east longitude, about 160 nautical miles northeast of the capital city of Antananarivo, Madagascar.

Jade's low pressure center had sustained winds near 45 knots (52 mph) but they are forecast to be around 25 knots (28 mph) later today, Apr. 7. Jade was moving south-southwest near 10 knots (11 mph), and by 10 a.m. EDT on April 7, Jade's center was over 80 miles south of Antananarivo.

The Tropical Rainfall Measuring Mission (TRMM) satellite data was used to create an image of Jade's soaking rains on April 6 at 12:09 UTC (8:09 a.m. EDT). By that time, Tropical Cyclone Jade had weakened from hurricane strength to tropical storm strength with winds of about 53 knots (~61 miles per hour). In this satellite image, Jade was still drenching northeastern Madagascar with bands of very heavy rainfall.

The precipitation analysis above was derived from TRMM's Thermal Microwave Imager and Precipitation Radar instruments. It shows that the storm was dropping over 50 millimeters per hour (~2 inches per hour) in areas along the eastern Madagascar coast south of the storms center. Jade was predicted to produce damage and more flooding as it moved southward over eastern Madagascar. Tropical cyclone symbols (in white) were overlaid on the image above to show Jade's predicted path.

Heavy rain amounts (from satellites) and flood inundation calculations (from a hydrological model) are updated every three hours globally with the results shown on the "Global Flood and Landslide Monitoring" TRMM web site pages.

For more information about how TRMM looks at rainfall, visit NASA's TRMM website at: http://trmm.gsfc.nasa.gov/. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

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

April 06, 2009

Cyclone Jade Forms Quickly and Makes Landfall in Madagascar

MODIS image of Tropical Cyclone Jade> Click for high resolution image
Credit: NASA/Jesse Allen MODIS Rapid Response Team
Cyclone Jade made landfall in northern Madagascar in the early morning hours of on Monday, April 6, 2009 as a Category one hurricane with sustained winds near 70 knots (80 mph). Heavy rains and gusty winds were reported by Zivoi.com just after midnight local time. Two instruments aboard NASA's Aqua satellite captured two different views of the storm, a visible image and an infrared image that shows cloud temperatures and indicates a storm's strength. The storm formed on Sunday, April 5.

By 06:00 UTC (2 a.m. EDT), the storm's sustained winds had dropped to 55 knots (63 mph), which is tropical storm strength. Tropical storm-force winds of up to 34 knots (39 mph) are still occurring outward up to 90 miles from the center of the storm.

Jade was centered near northeastern Madagascar, near 15.6 degrees south latitude and 50.0 degrees east longitude. That's about 265 miles northeast of Antananarivo. Antananarivo is the capital and largest city in Madagascar. The capitol city is located in the middle of the island, and is 90 miles from the eastern coast.

NASA's Aqua satellite flew over Jade and provided scientists with both a visible image of Jade's clouds, and a look at the temperatures of the storm's clouds.

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured a natural-color image of Cyclone Jade on April 6, 2009, at 10:30 UTC (6:30 a.m. Eastern Daylight Time).

AIRS image of Tropical Cyclone Jade> Click for larger image
Credit: NASA JPL, Ed Olsen
The Atmospheric Infrared Sounder (AIRS), another instrument aboard Aqua, captured an infrared image of Jade on April 6. The AIRS image clearly shows a large temperature difference between Jade's cloud tops or the surface of the Earth (land and water) in cloud-free regions.

In this image, the orange temperatures are 80F (300 degrees Kelvin) or warmer. Jade'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. The clouds and rain have a huge reach to the northwest and southeast way past the boundaries of the island nation, and into the open waters of the Southern Indian Ocean.

Jade is moving southwest at 9 knots (10 mph). Jade's forecast track carries the storm south over the island nation over the next two days. It will continue to weaken on its southern track and dissipate over land.

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