› Larger image NASA's TRMM satellite saw Garry moving through the open waters of the South Pacific Ocean on January 27, 2013 at 1530 UTC (10:30 a.m. EST/U.S.). The heaviest rainfall (green) was occurring south of Garry's center at a rate of 1 inch (30 mm) per hour. Credit: SSAI/NASA, Hal PierceNASA Sees Garry Become Extra-tropical and Fizzle
NASA's TRMM satellite captured an image of Garry's rainfall on Jan. 27 that showed rainfall rates had waned and the storm, now extra-tropical, was being battered by wind shear.
On Jan. 27, 2013 Cyclone Garry transitioned to an extra-tropical storm and the Joint Typhoon Warning Center issued their final advisory on the system. At 0900 UTC (4 a.m. EST, Garry was located near 24.0 South and 157.7 West, about 550 nautical miles (633 miles/1,019 km) southwest of Bora Bora, Society Islands. Garry was moving to the southeast.
Infrared satellite imagery showed that stratocumulus clouds (low clouds) were wrapping over the northern half of the storm and weakening the ability to produce thunderstorms. NASA's Tropical Rainfall Measuring Mission (TRMM) satellite captured an image of Garry's that showed the bulk of the storm's rainfall was occurring south of the center of circulation. The precipitation is being pushed south of the center from northerly wind shear. The heaviest rainfall that TRMM measured was occurring at a rate of 30 mm (1.18 inches) per hour. Wind shear was also elongating the storm. TRMM is a joint satellite mission between NASA and the Japanese Space Agency.
Wind shear hurts tropical cyclones because it removes the heat and moisture they need (to keep going) from the area near their core. Wind shear also elongates a tropical cyclone by blowing the top of the storm away from the bottom. An efficient tropical cyclone is stacked on top of itself in various levels of the atmosphere, like a stack of tires. If some of the tires at the top start leaning, the stack will fall over, just as a tropical storm loses its effectiveness to stay together. Whenever wind shear tilts the levels of a tropical cyclone, it becomes less effective in working as a heat engine. Tropical cyclones are basically heat engines that are powered by latent heat. That heat is created when water vapor condenses into liquid water. Without a heat engine, tropical cyclones, like Garry in this case, fall apart.
By Monday, Jan. 28, Garry had dissipated in the Southern Pacific Ocean.
› Larger image NASA's TRMM satellite saw tropical cyclone Garry moving through the open waters of the South Pacific Ocean on January 25, 2013 at 0909 UTC. The heaviest rainfall (red) was occurring in Garry's eastern quadrant at a rate of 2 inches (50 mm) per hour. Credit: SSAI/NASA, Hal Pierce
› Larger image This NASA AIRS infrared image of Cyclone Garry shows strong convection and cold cloud top temperatures (purple) wrapping around the center of circulation. The purple areas indicate cloud top temperatures of -63F (-52C) and are areas of powerful thunderstorms. Credit: NASA JPL, Ed OlsenNASA Sees Cyclone Garry's Strength Peaking in South Pacific
NASA's Aqua satellite identified powerful thunderstorms around the center of Cyclone Garry as the storm continued to intensify over warm waters of the South Pacific Ocean. Garry has prompted warnings for the southern group of the Cook Islands.
When NASA's Aqua satellite passed over Cyclone Garry the AIRS instrument captured an infrared image of Garry's clouds, providing temperature data to forecasters at the Joint Typhoon Warning Center (whom forecast tropical cyclones in that region). AIRS, the Atmospheric Infrared Sounder instrument, showed that there was a large area of powerful thunderstorms where cloud tops were so high that they were as cold as -63 degrees Fahrenheit (-52 Celsius). Those thunderstorms were producing heavy rainfall over the open waters of the Southern Pacific Ocean.
Cyclone Garry appeared to be near its peak on Jan. 25 when the storm's maximum sustained winds reached 85 knots (97.8 mph/157.4 kph). At 0900 UTC (4 a.m. EST) Garry's center was located near 16.6 south latitude and 160.2 west longitude, about 515 nautical miles (592.7 miles/953.8 km) west of Bora Bora. Garry was moving to the southeast at 15 knots (17.2 mph/27.7 kph).
Warnings and Watches Posted
The Fiji Meteorological Service has issued storm warnings for the southern group of the Cook Islands that include: Rarotonga, Aitutaki, Mangaia, Atiu, Mauke, Mitiaro, Palmerston, Manuae and Takutea.
A storm warning is in effect for Aitutaki, Manuae, Takutea and Atiu. Sustained winds of 60 knots (69 mph/111.1 kph) with higher gusts can be expected as Garry approaches and passes. Garry is expected to generate high seas and heavy rainfall that could produce flooding in low-lying coastal areas. A gale warning is in effect for Mauke, Mitiaro, Mangaia and Rarotonga. Squally thunderstorms with heavy rainfall may cause flooding in low-lying areas. Garry is expected to bring sustained winds of 40 knots (46 mph/74 kph) with higher gusts and rough seas.
A strong wind warning is in effect for the rest of the southern Cooks. Strong southeast winds with average speeds of 25 to 30 knots (28.7 to 34.5 mph / 46.3 to 55.5 kph) are expected with squally thunderstorms and periods of heavy rainfall. Seas are expected to be rough, and some low-lying flooding is possible. For updates on warnings and watches from the Fiji Meteorological Service, visit: http://www.met.gov.fj/current_warnings.php
Flyby of the tropical storm by the TRMM satellite. Credit: NASA
NASA's TRMM Satellite Measures Heavy Rainfall in Garry
NASA's Tropical Rainfall Measuring Mission (TRMM) satellite saw tropical cyclone Garry moving through the open waters of the South Pacific Ocean on January 25, 2013 at 0909 UTC (4:09 a.m. EST). Tropical Cyclone Garry was classified as a category two tropical cyclone on the Saffir-Simpson hurricane scale a couple hours earlier but had started to weaken when TRMM flew over. Sustained wind speeds were estimated to be less than 85 knots (~98 mph) and Garry is forecast to continue weakening while moving toward the southeast.
TRMM's main mission is to measure rainfall over tropics but has frequently been useful for monitoring tropical cyclones. The rainfall data compiled on Tropical Cyclone Garry was from two TRMM instruments. Rain rates in the Garry's center were taken from the TRMM Precipitation Radar (PR), the first precipitation radar in space, while rain rates in the outer swath were taken from the TRMM Microwave Imager (TMI). The heaviest rainfall was occurring in Garry's eastern quadrant at a rate of 2 inches (50 mm) per hour.
TRMM's Microwave Imager (TMI) is a passive microwave sensor designed to estimate rainfall in an 878 km (~545.6 miles) wide area by measuring the amount of microwave energy emitted by the Earth and its atmosphere. TRMM PR has a horizontal resolution at the ground of about 5.0 km (~3.1 miles) and sees a strip of the earth that is 154 miles (247 kilometers) wide.
TRMM PR can peer through obscuring clouds and provides 3-D vertical profiles of rain and snow from the Earth's surface up to a height of about 12 miles (20 kilometers). The 3-D and rainfall imagery is created at NASA's Goddard Space Flight Center in Greenbelt, Md.
Steering the Storm
The upper levels of the atmosphere are a major factor in the life and behavior of a tropical cyclone. Forecasters at the Joint Typhoon Warning Center (JTWC) analyzed the upper levels of the atmosphere above Garry and found that the system is deeply embedded in the prevailing westerly winds. Those upper level winds are contributing to Garry's intensification.
By Jan. 27, a trough (elongated area) of low pressure is expected to approach Garry and change its direction to a more east-southeasterly direction.
As Garry moves further to the south, forecasters at JTWC expect vertical wind shear to increase and make the storm decay. Garry is expected to become an extra-tropical cyclone over the next couple of days and become a cold core low by Jan. 29.
› Larger image NOAA's GOES-15 satellite captured this infrared image of Tropical Storm Garry about 330 miles east of Pago Pago, American Samoa. The image was taken Jan. 24 at 1500 UTC (10 a.m. EST). The bright white circle of clouds are strong thunderstorms wrapping around the center of circulation as Garry continues to intensify. Credit: NASA's GOES ProjectNASA Sees Tropical Cyclone Garry Continue to Intensify
Tropical Cyclone Garry is in a good environment to intensify and satellite imagery from NOAA's GOES-15 satellite helped confirm that the storm has become more organized.
NOAA's GOES-15 satellite captured an infrared image of Tropical Storm Garry when it was located about 330 nautical miles (379.8 miles/ 611.2 km) east of Pago Pago, American Samoa. The image, created by the NASA GOES Project at the NASA Goddard Space Flight Center in Greenbelt, Md., was taken Jan. 24 at 1500 UTC (10 a.m. EST). The image showed a bright white circle of clouds that indicate strong thunderstorms were wrapping around the center of circulation as Garry continues to intensify. The latest bulletin from the Joint Typhoon Warning Center noted that microwave satellite imagery confirmed deep convection wrapping almost entirely around Garry's well-defined low level circulation center.
NOAA's GOES-15 satellite is in a fixed orbit over the Pacific Ocean, midway between Hawaii and the West Coast and 22,300 miles above the equator. GOES-15 provides a good view of what is happening in U.S. west and in the Pacific Ocean.
On Jan. 24 at 0900 UTC, Garry's maximum sustained winds had increased to 60 knots (69 mph/111.1 kph). Garry's tropical-storm-force winds extend about 55 nautical miles (63.3 miles/102 km) from the center, making it a compact tropical cyclone. It was centered near 14.0 south latitude and 164.9 west longitude and moving to the southeast at 11 knots (12.6 mph/20.3 kph).
Forecasters at JTWC expect that Garry will continue moving southeast and is expected to pass far south of French Polynesia. Garry is expected to briefly reach cyclone (hurricane) strength before wind shear weakens and dissipates the storm.
› Larger image NASA's Aqua satellite passed over Tropical Storm Garry on Jan. 23 at 0053 UTC and AIRS instrument data revealed some very cloud top temperatures (purple) as cold as -63F (-52C). Credit: NASA JPL, Ed Olsen
› Larger image NASA's TRMM satellite viewed tropical cyclone Garry as it passed above on Jan. 21, 2012 at 2101 UTC. TRMM's data show that Garry's heaviest rain (red) of over 75mm (~3 inches) per hour was contained in an intense feeder band northeast of Garry's center of circulation. Credit: NASA/SSAI, Hal PierceNASA Sees Heaviest Rainfall in Tropical Storm Garry in a Feeder Band
A feeder band is a band of thunderstorms that wrap around a tropical cyclone and that's where NASA's TRMM satellite spotted the heaviest rainfall occurring in Tropical Storm Garry.
NASA's Tropical Rainfall Measuring Mission (TRMM) satellite viewed Tropical Cyclone Garry as it passed above on Jan. 21, 2012 at 2101 UTC (4:01 p.m. EST). TRMM's data show that Garry's heaviest rain of over 75mm (~3 inches) per hour was contained in an intense feeder band northeast of Garry's center of circulation.
When NASA's Aqua satellite passed over Tropical Storm Garry the next day, Jan. 23, at 0053 UTC, the Atmospheric Infrared Sounder (AIRS) instrument data revealed some very cloud top temperatures as cold as -63F (-52C) which are indicative of strong thunderstorms with heavy rainfall.
Garry is moving east of Samoa and headed southeast in the open waters of the Southern Pacific Ocean.
At 0900 UTC on Jan. 23, Garry's maximum sustained winds were near 45 knots (51.7 mph/83.3 kph). It was centered near 13.8 south latitude and 168.2 west longitude, about 145 nautical miles (167 miles/268.5 km) east-northeast of Pago Pago, American Samoa. Garry is moving to the southeast at 8 knots (9.2 mph/14.8 kph).
Garry is expected to intensify over the next couple of days and not affect any other land areas over the next several days.
This infrared image of Tropical Storm Garry was captured on Jan. 22 at 1241 UTC (7:41 a.m. EST) by the AIRS instrument that flies aboard NASA's Aqua satellite. The coldest cloud tops and strongest storms (purple) were south of the storm's center of circulation. Credit: NASA JPL, Ed Olsen › Larger imageNASA Sees Tropical Storm Garry Moving Past Samoa
Infrared satellite imagery from NASA showed that Tropical Storm Garry's power lies around its center as it was passing north of Samoa on Jan. 22.
The Atmospheric Infrared Sounder (AIRS) instrument that flies aboard NASA's Aqua satellite captured an infrared image of Tropical Storm Garry on Jan. 22 at 1241 UTC (7:41 a.m. EST). The coldest cloud tops and strongest storms appeared south of the tight center circulation. The coldest cloud top temperatures were near -63 Fahrenheit (-52 Celsius). There is also strong convection (rising air that forms thunderstorms) over the southeast quadrant and broken bands of thunderstorms north of the center.
Garry is the tenth tropical cyclone in the Southern Pacific Ocean season. In Fiji, Garry has is known as Tropical Cyclone 09F.
Garry was moving south-southeast on Jan. 22 and continued to pass north of Samoa while warnings remained in effect. A gale warning was in effect on Jan. 22 for Tutuila, Aunuu and Swains Island and a storm warning was effect for Manua.
On Jan. 22 at 0900 UTC (4 a.m. EST/U.S.), Garry had maximum sustained winds near 45 knots (51.7 mph/83.3 kph). Tropical –storm-force winds extended 50 nautical miles (57.5 miles/92.6 km) out from the center. Garry was centered near 13.2 south latitude and 169.8 west longitude, about 85 nautical miles (97.8 miles/157.4 km) northeast of Pago Pago, American Samoa. Garry is moving to the south-southeast at 6 knots (7 mph/11 kph).
Garry is forecast move slowly to the east and away from Samoa over the next several days, and intensify into a cyclone.