[image-110]NASA Sees Last Vestiges of Tropical Depression Jack
Tropical Cyclone Jack had weakened to a tropical depression when NASA and JAXA's Tropical Rainfall Measuring Mission (TRMM) satellite passed above on April 22, 2014 at 1120 UTC/7:20 a.m. EDT.
At that time, TRMM found that Jack was devoid of almost all rainfall near the tropical cyclone's center. Outside the center was a different story, however. That's where TRMM's precipitation radar instrument found rain falling at a rate of over 130mm/hr (about 5.1 inches) in a band of thunderstorms that stretched from east of Jack's center to the south. Some of the thunderstorms even stretched as high as 15 km (9.3 miles).
Wind shear continued to pummel the tropical cyclone and by April 23, Jack had fizzled in the Southern Indian Ocean.
Texxt credit: Harold F. Pierce
SSAI/NASA Goddard Space Flight Center
Apr. 22, 2014 - NASA Gets Two Last Looks at Tropical Cyclone Jack
Tropical Cyclone Jack lost its credentials today, April 22, as it no longer qualified as a tropical cyclone. However, before it weakened, NASA's TRMM satellite took a "second look" at the storm yesterday.
[image-36][image-108][image-78]The Tropical Rainfall Measuring Mission or TRMM satellite had two good views of Tropical Cyclone Jack on April 21, 2014 at 0404 UTC/12:04 a.m. EDT and again at 1215 UTC/8:15 a.m. EDT. TRMM is managed by NASA and the Japan Aerospace Exploration Agency known as JAXA.
Jack was moving in a south-southeast direction over the open waters of the South Indian Ocean far to the northwest of Australia.
When TRMM first passed over Jack, the storm had estimated sustained winds of 90 knots (103.6 mph/166.7 kph). The second time TRMM gathered data about Jack's rainfall, the storm's maximum sustained winds had dropped to 75 knots (86.3 mph/138.9 kph). Rainfall from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) were used to create images of rainfall rates. Rain was found by TRMM PR to be falling at a maximum rate of over 197 mm/hr. (7.8 inches) with the first pass and still falling at a rate of over 167 mm/hr. (6.6 inches) at the later time.
Although Jack was weakening on April 21, powerful thunderstorms tops were shown by TRMM PR to be reaching height of at least 17 km (10.5 miles) with both observations.
By April 22 at 0900 UTC/5 a.m. EDT, Jack had weakened so much that it no longer qualified as a tropical cyclone. At that time Jack's maximum sustained winds were down to 30 knots (34.5 mph/55.5 kph). It was centered about 350 nautical miles (402.8 miles/648.2 km) southwest of Cocos Island, near 17.8 south latitude and 95.2 east longitude.
Strong vertical wind shear stretched out the low-level circulation center. Multi-spectral satellite data also showed the low-level center was interacting with an area of stratocumulus clouds to the south and it appears that dry air moving into the system, which will further weaken it.
Jack's remnants are expected to continue moving on a southeastward track over open waters, where they will meet their end.
Text credit: Hal Pierce / Rob Gutro
NASA's Goddard Space Flight Center
[image-51]Apr. 21, 2014 - NASA Sees Wind Shear Affecting Newborn Tropical Cyclone Jack
Tropical Cyclone Jack may have hurricane-force winds today, April 21, but strong vertical wind shear is expected to weaken the storm. NASA's TRMM satellite passed overhead and saw that the bulk of the storm's rainfall was being pushed south of the center from the wind shear.
Tropical Cyclone Jack formed on Sunday, April 20, near 13.4 south and 91.1 east, and began moving to the south at 6 knots/6.9 mph/11.1 kph. Jack strengthened quickly and hours after its birth, the storm already had maximum sustained winds near 55 knots/63.2 mph/101.9 kph.
On April 21 at 0900 UTC/5 a.m. EDT, Tropical Cyclone Jack was moving through the Southern Indian Ocean at hurricane-force with maximum sustained winds near 75 knots/86.3 mph/138.9 kph. Jack was far from land and centered near 16.5 south latitude and 92.9 east longitude. That's about 346 nautical miles/398.0 miles/640.8 km southwest of Cocos Island. Jack was moving to the east-southeast at 10 knots/11.5 mph/18.5 kph.
The Joint Typhoon Warning Center noted that animated multispectral satellite imagery showed Jack continued in the buildup of thunderstorms despite strong vertical wind shear affecting them, and elongating the tropical cyclone to the southeast.
On April 21 at 04:02 UTC/12:02 a.m. EDT the microwave imager aboard NASA and the Japan Aerospace Exploration Agency's Tropical Rainfall Measuring Mission (TRMM) satellite was used to find an eye-like feature. By 12:15 UTC/8:15 a.m. EDT TRMM data no longer showed that eye-like feature. The Joint Typhoon Warning Center coupled TRMM data with infrared data from Europe's METEO-7 satellite to show Jack's clouds. That imagery showed how the rainfall was pushed to the south and southeast of the center by vertical wind shear.
Because of the increasing wind shear and the cooler sea surface temperatures in the direction Jack is moving, the storm is expected to weaken and dissipate in three days' time.
Text credit: Rob Gutro
NASA's Goddard Space Flight Center