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Tropical Storm Sonamu (Western North Pacific Ocean)
01.09.13
 
NASA's Terra Satellite Sees Sonamu's Remnants Fading Fast

satellite image of Sonamu

NASA's Terra satellite passed over Sonamu's remnants on Jan. 9 at 1513 UTC (10:13 a.m. EST) and the MODIS instrument captured an infrared image of the low pressure area. The remnant low did not have organized circulation.
Credit: NASA/NRL
› Larger image

Former Tropical Storm Sonamu's remnants are fizzling out in the South China Sea, north of eastern Malaysia.

The remnant low pressure area was located near 3.5 north latitude and 110.8 east longitude on Jan. 9. That's just over 100 miles northeast of Kuching, a coastal town and the capital and most populous city of the East Malaysian state of Sarawak.

NASA's Terra satellite passed over Sonamu's remnants on Jan. 9 at 1513 UTC (10:13 a.m. EST) and the Moderate Resolution Imaging Spectroradiometer captured an infrared image of the low pressure area. The remnant low did not have organized circulation.

The remnant low's maximum sustained winds have fallen below 20 knots (23 mph/37 kph) as it continues to dissipate.

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



AIRS image of Sonamu› Larger image
This AIRS infrared image of Tropical Depression Sonamu on Jan. 8 at 1:41 a.m. EST, showed some very cold cloud top temperatures (purple) of -63F (-52C) existed, indicating there was still some strong convection occurring. Credit: NASA JPL, Ed Olsen
NASA Watches a Slow-moving Tropical Depression Sonamu

Tropical Depression Sonamu has been consistently slow moving over the last couple of days, and that has not changed. NASA's Aqua satellite captured an infrared image of the stubborn storm lingering in the South China Sea, and it still contained some strong thunderstorms.

When NASA's Aqua satellite passed over Tropical Depression Sonamu on Jan. 8 at 0641 UTC (1:41 a.m. EST/U.S.), the Atmospheric Infrared Sounder (AIRS) instrument aboard took an infrared look at the storm. AIRS data showed that Sonamu still contained some very cold cloud top temperatures of -63F (-52C) indicating there was still some strong convection occurring near the center of circulation. The strongest storms were located southwest of the Mekong Delta at the time of the satellite image.

Multispectral satellite imagery showed that the low level circulation center was exposed to outside winds, and that the center was disorganized.

By 1500 UTC (10 a.m. EST/U.S.), Sonamu's maximum sustained winds were near 30 knots (34.5 mph/55.5 kph). Sonamu was centered near 5.3 north latitude and 109.3 east longitude, about 335 nautical miles (385.5 miles/620.4 km) west of Brunei. It was drifting to the southeast at 3 knots (3.4 mph/5.5 kph).

Sonamu is expected to continue its slow movement to the southeast and weaken further as wind shear increases. The Joint Typhoon Warning Center expects that Sonamu will make a landfall sometime on Jan. 10 in the Malaysian part of Borneo.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center



Jan. 07, 2013

MODIS image of Sonamu› Larger image
NASA's Aqua satellite passed over Sonamu on Jan. 7, 2013 and noticed that the eastern half of the storm was almost devoid of clouds and showers, which is an effect of the dry air intrusion. The bulk of the cloud cover was west of the center. Credit: NASA/NRL
Wind Shear and Dry Air Bashing Tropical Depression Sonamu

Once a cyclone, now a tropical depression, Sonamu is being battered by moderate wind shear and an intrusion of dry air and it has practically stalled in the South China Sea.

On Sunday, Jan. 6, Tropical Storm Sonamu's maximum sustained winds were near 40 knots (46 mph/74 kph). Sonamu's center was located about 255 nautical miles (258.9 miles/416.7 km) southeast of Ho Chi Minh City, Vietnam, near 7.2 north and 108.9 east and continued to move west. At that time, the ragged low level center became exposed to outer winds. Satellite data showed that the strongest convection and heaviest rainfall was now pushed to the north because of wind shear.

On Monday, Jan. 7, Sonamu was curving to the southwest and is now expected to miss the Malay Peninsula. The Malay Peninsula contains the southernmost tip of Myanmar, Peninsular Malaysia, Singapore, and Southern Thailand. Sonamu is now expected to continue slowly on a southerly track.

Sonamu's maximum sustained winds are down to 30 knots (34.5 mph/55.5. kph). At 1500 UTC (10 a.m. EST/U.S.), Sonamu was located near 6.1 north latitude and 108.3 east longitude, about 290 nautical miles (333.7 miles/537.1 km) south-southeast of Ho Chi Minh City, Vietnam. Sonamu is crawling to the southwest at 1 knot (1 mph/1.8 kph). Sonamu is battling moderate wind shear, which is weakening the storm.

NASA's Aqua satellite passed over Sonamu on Jan. 7 and noticed that the eastern half of the storm was almost devoid of clouds and showers, which is an effect of the dry air intrusion. The Moderate Resolution Imaging Spectroradiometer captured an infrared image of the storm that showed the bulk of the cloud cover was west of the center.

According to the Joint Typhoon Warning Center on Jan. 7, infrared imagery shows a rapidly deteriorating, partially exposed low level circulation center with flaring convection along the western edge of the storm. Water vapor imagery indicated a pocket of dry air is wrapping along the eastern half of the low-level center toward Sonamu's center. Dry air saps convection, which forms the thunderstorms that make up a tropical cyclone.

Forecasters at the Joint Typhoon Warning Center expect that the combination of wind shear and dry air will lead to the dissipation of Sonamu over the next couple of days in the South China Sea.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center



Jan. 04, 2013

This visible image of Tropical Storm Sonamu in the South China Sea was captured by the MODIS instrument aboard NASA's Aqua satellite on Jan. 4, 2013 › View larger
This visible image of Tropical Storm Sonamu in the South China Sea was captured by the MODIS instrument aboard NASA's Aqua satellite on Jan. 4, 2013 at 0535 UTC (12:35 a.m. EST). Credit: NASA Goddard MODIS Rapid Response Team
NASA Catches Tropical Storm Sonamu in South China Sea

Sonamu has left the Philippines and Palawan behind and NASA satellite imagery showed the storm intensified into a tropical storm while moving through the easternmost South China Sea.

At Jan. 4, 2013 at 0535 UTC (12:35 a.m. EST), a visible image of Tropical Storm Sonamu was captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument that flies aboard NASA's Aqua satellite.

The Joint Typhoon Warning Center (JTWC) noted that some animated infrared satellite imagery shows central convection persisting over the low level circulation center and some fragmented formative banding over the northern semi-circle.

By 1500 UTC (10 a.m. EST/U.S.), Sonamu's maximum sustained winds had increased to near 35 knots (40.2 mph/64.8 kph). Sonamu's center was located near 8.9 north latitude and 113.2 east longitude, about 430 nautical miles (494.8 miles/ 796.4 km) east-southeast of Ho Chi Minh City, Vietnam. Sonamu is moving to the west at 14 knots (16.1. mph/26 kph) and is expected to continue in that general direction for the next couple of days with its center staying over open waters as it passes southern Vietnam.

Extreme southern Vietnam, from near Ho Chi Minh City southward may feel the effects of the outer fringes of the storm, with gusty winds, heavy rainfall, and rough coastal conditions.

JTWC forecasters expect that Sonamu will peak in intensity sometime on Jan. 5 and then weaken as vertical wind shear increases.

Sonamu is forecast to turn to the south-southwest and make landfall early next week in east central Malaysia.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center



Jan. 03, 2013

MODIS image of Sonamu› Larger image
When NASA's Terra satellite passed over Depression Sonamu on Jan. 3 at 9:13 a.m. EST/U.S. the center was approaching southern Palawan. Credit: NASA/NRL
NASA Sees Tropical Depression Sonamu Form Near Philippines

The first Tropical Depression of 2013 formed the western North Pacific Ocean today, and NASA's Terra satellite captured an infrared image of the "birth."

Tropical Depression Sonamu, otherwise known as Tropical Depression 01W developed near 8.6 north latitude and 118.6 east longitude, about 185 nautical miles (213 miles/342.6 km) northwest of Zamboanga, Philippines. Sonamu's center is located in the Sulu Sea and is expected to cross the southern end of Palawan before moving into the open waters of the South China Sea.

Sonamu developed from low pressure System 92W. At 1500 UTC (10 a.m. EST/U.S.), Sonamu had maximum sustained winds near 25 knots (28.7 mph/46.3 kph) and is expected to struggle to intensify as moderate to strong vertical wind shear continues to impact the storm. Sonamu is moving to the west at 17 knots (19.5 mph/31.8 kph) and is expected to continue in that general direction for the next couple of days.

When NASA's Terra satellite passed over Sonamu on Jan. 3 at 1413 UTC (9:13 a.m. EST/U.S.) the center was approaching southern Palawan. The Moderate Resolution Imaging Spectroradiometer or MODIS instrument captured an infrared image of Sonamu that showed its clouds had overspread southern Palawan.

Forecasters at the Joint Typhoon Warning Center, who forecast tropical cyclones in that area of the world, noted that infrared imagery showed that the low-level center is consolidating, and there is strong convection (rapidly rising air that condenses and forms the thunderstorms that make up a tropical cyclone) around the center. Satellite data also shows some banding of thunderstorms wrapping around the center.

By 0000 UTC on Jan. 4 (Jan. 3 at 7 p.m. EST/U.S.) Sonamu will have crossed Palawan and entered the South China Sea, where it is expected to track for the next several days.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center