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Hurricane Season 2011: Tropical Cyclone Wilma (Southern Pacific)
01.31.11
 
Tropical Cyclone Wilma Now Soggy a Memory in Northern New Zealand

Tropical Cyclone Wilma brought heavy rainfall to much of northern New Zealand over the weekend and has now dissipated in the Southern Pacific Ocean.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite saw that Wilma had rainfall rates near 2 inches per hour (50 mm). Local weather reports noted record rainfall for Coromandel Town on January 29. Coromandel Town is located on the Coromandel Peninsula near Mcgregor Bay. It is south of the Huaraji Gulf. Coromandel Town reported the highest daily rainfall on January 29, totaling 171.9 mm (6.76 inches).

Heavy rainfall from Wilma caused flooding on roadways and low-lying areas. Excessive rainfall also caused rivers to overflow in Auckland, Coromandel, the Bay of Plenty and in Waikato. River levels in Waikato were expected to recede today.

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



January 28, 2011

NASA Sees Cyclone Wilma Bring Rains to Northern New Zealand: Warnings and Watches Up

When TRMM captured Wilma's rainfall on Jan. 28, it showed light to moderate rainfall extended to the southwest of the center. › View larger image
When TRMM captured an image of Cyclone Wilma's rainfall on Jan. 28 at 0248 UTC it showed light to moderate rainfall extended to the southwest of the center. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 to 40 mm) per hour. Red areas are heavy rainfall at almost 2 inches (50 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
NASA's Tropical Rainfall Measuring Mission (TRMM) satellite is measuring Cyclone Wilma's rainfall from space as it continues raining on northern New Zealand today. It is already become an extra-tropical cyclone.

A Severe Weather Watch was in effect at 11 a.m. EST on January 28 (5:10 a.m. on Saturday January 29 in Pacific/Auckland local time) for Northland, Auckland, Coromandel Peninsula, Waikato, Bay Of Plenty, Rotorua, Taupo, Gisborne, Hawkes Bay, Southland and Otago. Those areas are experiencing very heavy rain and gusty winds.

When the TRMM satellite captured an image of Cyclone Wilma's rainfall on the morning of Jan. 28 at 0248 UTC, light to moderate rains extended southwest of Wilma's center. Rain was falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour.

TRMM images are pretty complicated to create. They're made at NASA's Goddard Space Flight Center in Greenbelt, Md. At Goddard, rain rates in the center of the swath (the satellite's orbit path over the storm) are created from the TRMM Precipitation Radar (PR) instrument. The TRMM PR is the only space borne radar of its kind. The rain rates in the outer portion of the storm are created from a different instrument on the satellite, called the TRMM Microwave Imager (TMI). The rain rates are then overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). For more information about TRMM, visit: http://www.trmm.gsfc.nasa.gov.

At 11 a.m. EST on January 28 (5:10 a.m. on Saturday January 29 in Pacific/Auckland local time) Tropical Cyclone Wilma was about 170 miles (280km) north of Cape Reinga at 6 p.m. local time on January 28 (12 a.m. EST) and was moving south-southeast.

At 1:00 p.m. EST on Jan. 28 (7 a.m. in Pacific/Auckland local time), the Airport in Auckland was reporting rain with a temperature of 68 Fahrenheit (20 Celsius) and sustained winds of 24 mph (~38 km/hr) from the southwest. Pressure was rising, indicating that the center of Wilma had already passed.

Wilma has already transitioned to an extra-tropical area of low pressure, and was moving rapidly southeast to the east of New Zealand. However, large ocean swells and are still affecting eastern coastal areas from Northland to East Cape.

For updated warnings and forecasts, visit The New Zealand Meteorological Service website at: http://www.metservice.com/national/warnings/index.

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



January 27, 2011

Tropical Cyclone Wilma Headed to New Zealand, TRMM Sees Heavy Rainfall

Red areas near Wilma's center are considered heavy rainfall at almost 2 inches per hour. › View larger image
The TRMM satellite saw tropical cyclone Wilma during the daytime on January 27, 2011 when it still had powerful winds estimated at a little less than 100kts (~115 mph). The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches per hour. Red areas near Wilma's center are considered heavy rainfall at almost 2 inches per hour.
Credit: NASA/SSAI, Hal Pierce
Tropical cyclone Wilma caused extensive property damage in Samoa and Tonga, is expected to weaken and affect New Zealand with gale force winds on January 28, 2011.

The TRMM satellite saw tropical cyclone Wilma during the daytime (local time, Auckland, New Zealand) on January 27, 2011 when it still had powerful winds estimated at a little less than 100 knots (~115 mph). Rainfall derived from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) show that Wilma had a large area of rainfall with the heaviest rainfall in the southeastern quadrant of the storm.

The heaviest rainfall was occurring at a rate of more than 2 inches (55 mm) per hour. Tonga' National Disaster Centre reported that low-lying areas in the Ha'apai island group encountered the greatest damages. Electricity is in the process of being restored, while many houses and buildingss were damaged or collapsed under Wilma's intense winds.

The New Zealand Meteorological Service issued a statement today about Wilma's approach, "Tropical Cyclone Wilma is expected to pass close to the northeast of the North Island early on Saturday." For local forecasts on Wilma go to: http://www.metservice.com/national/index/.

On January 27 at 0900 UTC (4 a.m. EST/ 10 p.m. local time Pacific/Auckland) Wilma's maximum sustained winds were near 115 knots (132 mph/213 km/hr). It was about 555 nautical miles east of Noumea, New Caledonia near 23.6 South and 175.5 East. It was moving west-southwestward at 11 knots (13 mph/20 km/hr).

Satellite imagery was still showing a highly symmetrical cyclone with a well-defined eye that has decreased to 10 nautical miles (11.5 miles/18.5 kilometers) in diameter. Forecasters at the Joint Typhoon Warning Center noted that the system is showing signs of eyewall replacement, which usually happens in powerful cyclones/hurricanes.

Wilma is expected to remain at sea for another day and begin slowing down before curving to to southeast. It will be pushed by an approaching trough (elongated area of low pressure) toward northern New Zealand. Wilma is headed into cooler waters that will sap the storm of energy and wind shear is expected to increase as well, so the system should weaken and transition into an extra-tropical storm.

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



January 26, 2011

NASA Sees Wilma Become a Major Cyclone in the South Pacific

Storm Wilma › View larger image
On Jan. 26 at 01:45 UTC, the MODIS instrument aboard NASA's Aqua satellite showed a well-defined eye in Wilma about 10 nautical miles in diameter.
Credit: NASA Goddard/MODIS Rapid Response Team
Wilma has become a major Tropical Cyclone in the Southern Pacific Ocean today and NASA's Aqua satellite captured a stunning image showing a clear eye. Cyclone Wilma has become a Category 4 cyclone with maximum sustained winds near 132 mph while remaining away from land areas.

At 0900 UTC (4 a.m. EST) Tropical Cyclone Wilma's maximum sustained winds were near 132 mph/213 km/hr. A category four hurricane/cyclone has maximum sustained winds between 131-155 mph. Wilma was located about 555 nautical miles east of Noumea, New Caledonia near 23.6 South and 175.5. East. It was moving west-southwestward at 11 knots (13 mph / 20 km/hr).

Wilma is a highly symmetrical cyclone. The Moderate Resolution Spectroradiometer (MODIS) instrument aboard NASA's Aqua satellite showed a well-defined eye about 10 nautical miles (11.5 miles/18.5 km) in diameter.

Wilma is being steered by a subtropical ridge (elongated area of high pressure) located to its southeast. It is forecast by the Joint Typhoon Warning Center to continue moving west-southwest and then turn to the southeast in 24 hours. After its turn it is forecast to run into vertical wind shear which will begin to weaken the system as it starts becoming extra-tropical on its way to northern New Zealand.

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



January 25, 2011

Cyclone Wilma's Eye Catches Attention of NASA Satellites

This AIRS image shows a well-organized storm with a visible eye. › View larger image
NASA's Aqua satellite captured visible and infrared images of Cyclone Wilma on January 25 at 00:59 UTC. This visible image shows a well-organized storm with a visible eye.
Credit: NASA/JPL, Ed Olsen
The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 and 40 mm) per hour. › View larger image
Tropical cyclone Wilma was seen by the TRMM satellite shortly after attaining hurricane intensity on January 24, 2011 at 2128 UTC. The yellow and green areas indicate moderate rainfall between .78 to 1.57 inches (20 and 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
Wilma caught the eye of NASA. NASA's Aqua satellite captured visible and infrared images of Cyclone Wilma in the Southwestern Pacific Ocean and her eye was clearly visible from space.

On January 25 at 00:59 UTC (8:59 p.m. EST on Jan. 24), the Atmospheric Infrared Sounder (AIRS) instrument captured data that was used to create infrared and visible images at NASA's Jet Propulsion Laboratory in Pasadena, Calif. The images showed Cyclone Wilma had strengthened overnight and now has a visible eye.

AIRS Infrared imagery showed strong, very cold thunderstorm cloud tops around Wilma's center of circulation. The cloud tops were as cold as or colder than -63 Fahrenheit (-52 Celsius) indicating strong convection (rapidly rising air that creates the thunderstorms that power a tropical cyclone). Animated infrared satellite imagery showed a 25 nautical mile (29 mile/46 km) diameter ragged eye with tightly-curved banding of thunderstorms wrapping into the center.

AIRS instrument data also showed what appears to be a large "tail" from Wilma's center, stretching several hundred miles (kilometers) to the northeast of the storm's center.

Tropical cyclone Wilma was also seen by the Tropical Rainfall Measuring Mission (TRMM) satellite shortly after attaining hurricane intensity on January 24, 2011 at 2128 UTC 2:28 p.m. EST). The system had mostly moderate rainfall, falling at rates between .78 to 1.57 inches (20 and 40 mm) per hour. The TRMM satellite is managed by both NASA and JAXA, and TRMM data and imagery was created at NASA's Goddard Space Flight Center in Greenbelt, Md.

On January 25 at 0900 UTC (4 a.m. EST), Tropical Cyclone Wilma had maximum sustained winds near 85 knots (97 mph/157 km/hr). It was located about 360 nautical miles southeast of Nadi, Fiji near 22.0 South and 178.2 West. It was moving southwestward near 24 knots (27 mph/ 44 km/hr).

A Tropical Cyclone Warning is in force for areas of Tonga and for areas of Fiji. On its projected path, Tropical Cyclone Wilma is expected to pass about 124 miles (200 km) south-southeast of Ono-i-lau by midnight local time tonight.

Republic of the Fiji Islands is an island nation in Melanesia in the South Pacific Ocean about 1,243 miles (2,000 km) northeast of New Zealand's North Island. Vanuatu is located to the west, and New Caledonia is located to the southwest. Tonga is located east of Fiji. Tonga is an archipelago comprised of 176 islands scattered over 270,000 square miles (700,000 square kilometers).

Wilma is forecast to continue moving southwest parallel to Fiji and New Caledonia as it makes its way toward New Zealand. On January 28 it is forecast to change course and head southeast bringing rains and gusty winds to northern New Zealand.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD



January 24, 2011

NASA Satellite Peels Back the Rain Envelope in Cyclone Wilma Over Samoa

TRMM saw scattered intense thunderstorms (red) with rainfall over 50 mm/hour on January 23, 2011 › View larger image
NASA's TRMM satellite passed above Wilma on January 23, 2011 at 2046 UTC and saw scattered intense thunderstorms (red) with rainfall over 50 mm/hour (~2 inches) were still embedded in the storm's main circulation over open ocean, particularly north and east of the center of circulation.
Credit: NASA/NASA, Hal Pierce
AIRS captured an infrared image of Wilma's cloud top temperatures. › View larger image
NASA's Aqua satellite passed over Cyclone Wilma on January 24 at 12:47 UTC (7:47 a.m. EST) and the AIRS instrument captured an infrared image of its cloud top temperatures. The coldest cloud tops appear in purple (-63 Fahrenheit/-53 Celsius) and indicate the strongest thunderstorms and areas of likely heavy rainfall.
Credit: NASA/JPL, Ed Olsen
NASA's TRMM satellite passed over Tropical Cyclone Wilma and "peeled back" the clouds of the storm to look into the rate in which rain was falling within the storm. Some areas were dropping heavy rain at more than 2 inches (50 mm) per hour.

A tropical disturbance west of Samoa became tropical Cyclone Wilma on January 22, 2011. At that time it was about 165 miles north-northwest of Pago Pago.

Currently, regional warnings are in effect for Tonga and Tokelau and for the Lau group of islands, Moala, Fiji. The cyclone may bring damaging winds to the Southern Lau group later today. Low level flooding is also likely in the warning areas.

Tropical Cyclone Wilma then buffeted Samoa with little damage and was moving toward the south when the Tropical Rainfall Measuring Mission (TRMM) satellite passed above on January 23, 2011 at 2046 UTC (3:46 p.m. EST). That image showed that skies were clearing over Samoa as Wilma's center had moved east. Wilma's scattered intense thunderstorms with rainfall over 50 mm/hour (~2 inches) were still embedded in the storm's main circulation over open ocean, particularly north and east of the center of circulation. TRMM is managed by both NASA and the Japanese Space Agency.

The National Weather Service in American Samoa reported sustained winds up to 60 mph with higher gusts occurred. Heavy rainfall also caused mudslides and some power outages were reported.

Microwave imagery today shows tightly curved bands of thunderstorms wrapping into the low-level center of the cyclone. The strongest convection and heaviest rainfall was occurring along the south and eastern edges of the center of circulation.

When NASA's Aqua satellite passed over Cyclone Wilma on January 24 at 12:47 UTC (7:47 a.m. EST) the Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of its cloud top temperatures. The coldest cloud tops were as cold as or colder than -63 Fahrenheit/-53 Celsius indicating the strongest thunderstorms and areas of heavy rainfall. AIRS infrared data also showed that the highest, coldest cloud tops were around the center of circulation and in the eastern quadrant of the storm, paralleling the TRMM data that said heaviest rainfall was occurring in the eastern quadrant of the storm.

The Joint Typhoon Warning center forecasts Wilma to turn slowly southward and begin to weaken because of cooler sea surface temperatures.

By January 25 Wilma is predicted to intensify to a category one cyclone on the Saffir-Simpson scale with winds of about 70 knots (~80.5 mph) while moving toward the southwest. Wilma is then forecast to become extra-tropical. Current forecast tracks take Wilma toward Auckland, New Zealand by the end of this week.

Text Credit: Rob Gutro
NASA Goddard Space Flight Center, Greenbelt, MD