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Hurricane Season 2012: Tropical Cyclone Iggy (Southern Indian Ocean)
02.03.12
 
Bands of heavy rainfall (in red) measuring over 50mm/hr were hitting coastal areas northwest of Perth, Australia. › View larger image
The image showed that bands of heavy rainfall (in red) measuring over 50mm/hr (~2 inches) were hitting coastal areas northwest of Perth, Australia. A red tropical storm symbol shows where Iggy's center was located.
Credit: NASA/SSAI Hal Pierce TRMM Satellite Saw Heavy Rainfall When Cyclone Iggy Hit Australia's Sunset Coast

Tropical Cyclone Iggy is now a memory in southwestern Australia but it made its presence known when it made landfall on Australia's Sunset coast on February 2, 2012. NASA's TRMM satellite provided measurements of rainfall rates as it headed toward landfall and noticed heavy rain was falling in some coastal areas.

Sunset Coast is the section of the coastline in Western Australia that encompasses the northern area of Perth, according to the Tourism Western Australia. Perth is the capital city of Western Australia.

On February 2, 2012 at 1044 UTC (5:44 a.m. EST) the Tropical Rainfall Measuring Mission (TRMM) satellite saw weakening Tropical Storm Iggy as it was approaching the coast of southwestern Australia. An image of rainfall rates was created at NASA's Goddard Space Flight Center in Greenbelt, Md. NASA co-manages TRMM with the Japanese Space Agency.

The image was created using data from both TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments. The image showed that bands of heavy rainfall measuring over 50mm/hr (~2 inches) were hitting coastal areas northwest of Perth, Australia. Iggy has since dissipated as it moved eastward into interior area of Western Australia.

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


Feb. 2, 2012

MODIS captured a true color image of Tropical Cyclone Iggy on Feb. 2, 2012 at 0615 UTC › View larger image
NASA's Aqua satellite passed over Tropical Cyclone Iggy on Feb. 2, 2012 at 0615 UTC (1:15 a.m. EST). The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a true color image of the storm. In the image, Iggy appears elongated from northwest to southeast, which is the direction of the wind shear.
Credit: NASA Goddard MODIS Rapid Response Team
AIRS captured infrared images and cloud temperatures of Tropical Cyclone Iggy on Feb. 1 at 1805 UTC › View larger image
AIRS instrument captured infrared images and cloud temperatures of Tropical Cyclone Iggy on Feb. 1 at 1805 UTC (1:05 p.m. EST). The small purple area pushed southeast of the center from wind shear indicates the coldest cloud tops and strongest thunderstorms.
Credit: NASA/JPL, Ed Olsen NASA Satellites See Wind Shear Battering Tropical Depression Iggy

NASA satellites have watched as wind shear has torn Cyclone Iggy apart over the last day. NASA infrared satellite imagery showed that Iggy's strongest thunderstorms have been pushed away from the storm's center and visible imagery shows the storm is being stretched out. Iggy is weakening and heading for a landfall between Geraldton and Perth.

When NASA's Aqua satellite passed over Tropical Cyclone Iggy on Feb. 1 at 1805 UTC (1:05 p.m. EST), the Atmospheric Infrared Sounder (AIRS) instrument aboard captured an infrared look at the cyclone. AIRS data showed that the strongest thunderstorms (with the coldest cloud top temperatures) had been pushed to the southeast of Iggy's center. That convection was pushed by vertical wind shear from the northwest. Once convection is pushed away from a tropical cyclone's center, the storm begins to fall apart. Tropical cyclones must be stacked in the atmosphere like a haystack. If the middle (convection in this case) gets pushed out, then the storm collapses.

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Aqua satellite captured a true color image of Iggy when it passed overhead on Feb. 2, 2012 at 0615 UTC (1:15 a.m. EST). The MODIS image clearly shows how the wind shear is affecting the tropical depression because Iggy appears elongated from northwest to southeast, which is the direction of the wind shear.

The Australian Bureau of Meteorology (ABM) issued severe weather warnings for residents from Kalbarri to Morawa, and from Morawa to Wongan Hills; and Wongan to Narrogin and Harvey. The ABM website noted that the warning includes people in, near or between the following towns: Geraldton, Jurien Bay, Perth, Mandurah, York and Narrogin. Those areas can expect thunderstorms with heavy rainfall, and gusty winds as Iggy continues moving east. Flash flooding is also a possibility from the heavy rainfall.

On February 2, 2012, Tropical Depression Iggy had maximum sustained winds near 30 knots (~35 mph/~56 kph). It was located about 170 nautical miles (~196 miles/~315 km) northwest of Perth, Western Australia, and its center was near 29.9 South latitude and 114.2 East longitude. Iggy was moving to the east at 14 knots (16 mph/~26 kph) and is expected to continue in that direction making landfall before 0300 UTC on February 3, 2012 (or before 10 p.m. EST, Feb. 3). Iggy is expected to quickly weaken to a remnant low as it moves further inland in Western Australia.

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


Feb. 1, 2012

TRMM data from Feb. 1, 2012 revealed that Iggy had a large area of moderate to heavy rainfall (red) south of the center of circulation. › View larger image
TRMM data from Feb. 1, 2012 revealed that Iggy had a large area of moderate to heavy rainfall (red) south of the center of circulation. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) indicated that rainfall intensity was over 30mm/hr (~1.2 inches) in some locations. Iggy's past and forecast locations are shown with appropriate white tropical cyclone symbols on the image above.
Credit: SSAI/NASA, Hal Pierce
This 3-D view of Iggy was created using TRMM Precipitation Radar (PR) data from Feb. 1, 2012. › View larger image
This 3-D view of Iggy was created using TRMM Precipitation Radar (PR) data from Feb. 1, 2012. This view shows that a broken band of storms around Iggy's center of circulation were fairly shallow and weak with heights reaching to at most about 9km (~5.6 miles).
Credit: SSAI/NASA, Hal Pierce TRMM Satellite Still Showing Heavy Rainfall In Cyclone Iggy

Cyclone Iggy continues to track parallel to the coast of Western Australia and generate heavy rainfall, according to data from the Tropical Rainfall Measuring Mission (TRMM) satellite.

The TRMM satellite passed above tropical storm Iggy on February 1, 2012 at 0647 UTC as the storm was heading toward the coast of southwestern Australia. Iggy was briefly categorized as a category one tropical cyclone on the Saffir-Simpson scale but is predicted to be a weak tropical storm with winds of about 35 knots (~40 mph) when it moves over the Australian coast.

TRMM data showed Iggy had a large area of moderate to heavy rainfall south of the center of circulation. TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) indicated that rainfall intensity was over 30mm/hr (~1.2 inches) in some locations.

A 3-D view of Iggy was created at NASA's Goddard Space Flight Center in Greenbelt, Md. using TRMM Precipitation Radar (PR) data. This view shows that a broken band of storms around Iggy's center of circulation were fairly shallow and weak with heights reaching to at most about 9km (~5.6 miles).

On February 1, 2012, Tropical Cyclone Iggy's maximum sustained winds had increased to 60 knots (69 mph/111 kph). It was about 410 nautical miles (472 miles/759 miles) west-northwest of Perth, Australia, centered near 28.9 South latitude and 109.4 East longitude. It was moving to the southeast at 14 knots (~16 mph/~26 kph) and has entered cooler waters. Water temperatures colder than 80F (26.6 C) cannot maintain a tropical cyclone, so whenever they enter waters less than that, cyclones begin to weaken. The water temperatures in the region are around 23 Celsius (73.4F).

Despite the cooler waters, Iggy is still holding together with an organized core of convection (rising air that forms thunderstorms that make up a tropical cyclone) and a weak eye structure. The eye, however, appears to be elongating, which is a sign that the storm is battling wind shear and may weaken.

The Australian Bureau of Meteorology issued a tropical cyclone statement on Feb. 1: "It is not expected to cause gales in Western Australian (WA) communities but could contribute to strong winds, hazardous fire weather conditions, thunderstorms and rain in parts of the Southwest Land Division. Please refer to WA forecasts and warnings."

Iggy is forecast to turn to the east and weaken quickly in the cooler waters as wind shear increases. The Joint Typhoon Warning Center forecast takes Iggy over land by February 3 in the vicinity of Geraldton, Western Australia.

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


Jan. 31, 2012

AIRS captured infrared images and cloud temperatures of Iggy on Jan. 31 at 0623 UTC (1:23 a.m. EST). › View larger image
AIRS captured infrared images and cloud temperatures of Tropical Cyclone Iggy on Jan. 31 at 0623 UTC (1:23 a.m. EST). Purple areas indicate the coldest cloud tops and strongest thunderstorms. Most of the strong thunderstorms surround the center of circulation.
Credit: NASA/JPL, Ed Olsen NASA Sees Strong Thunderstorms Still Surround Cyclone Iggy's Center

NASA's Aqua satellite passed over Tropical Cyclone Iggy on January 31 and the AIRS infrared instrument aboard showed that there is a large area of strong thunderstorms still surrounding Iggy's center of circulation.

The Atmospheric Infrared Sounder Instrument called AIRS that flies aboard NASA's Aqua satellite captures infrared data and basically takes the temperature of cloud tops in tropical cyclones. That's a critical component of a tropical cyclone because the colder the cloud top, the stronger the uplift and energy in the storm. The threshold that indicates strongest thunderstorms and highest cloud tops is -63 Fahrenheit (-52.7 Celsius) in AIRS data, and cloud tops around Iggy's center were colder than that. That means there is still a lot of strength in the storm. AIRS data also shows there are tight bands of thunderstorms that are wrapping into the center of the storm. Microwave data from NASA's Aqua satellite showed an eye in the storm, despite its status as a tropical storm.

On January 31 at 1500 UTC (10 a.m. EST) Tropical Cyclone Iggy's maximum sustained winds had decreased to 50 knots ~58 mph/~93 kph). It was located 330 nautical miles (380 miles/611 km) west-southwest of Learmonth, Australia, near 24.5 South latitude and 108.3 East longitude. It is moving to the south-southwest at 13 knots (15 mph/24 kph). The storm is just over 220 nautical miles (~253 miles/~407 km) in diameter.

Iggy has begun moving to the south-southwest, and is expected to curve back later southeast towards southwestern Australia. Current forecasts expect Iggy to weaken as it runs into strong wind shear and cooler waters. Iggy may dissipate before making landfall.

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


Jan. 30, 2012

MODIS captured a true color image of Tropical Cyclone Iggy on January 30, 2012. › View larger image
NASA's Aqua satellite passed over Tropical Cyclone Iggy on January 30, 2012. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a true color image of the storm. Western Australia's Pilbara coastline is clearly visible to the east.
Credit: NASA Goddard MODIS Rapid Response Team
AIRS measured Iggy's cloud (purple) top temperatures on January 29 at 635 UTC (1:35 a.m. EST). › View larger image
When NASA's Aqua satellite passed over Cyclone Iggy on January 29 at 635 UTC (1:35 a.m. EST) the AIRS instrument measured the cloud (purple) top temperatures. Thunderstorm cloud tops around the entire center of circulation were colder than -63 Fahrenheit (-52.7 Celsius) indicating strong storms. Western Australia is located to the east (right).
Credit: NASA/JPL, Ed Olsen NASA Sees Cyclone Iggy Skirting the Western Australia Coastline

NASA captured visible and infrared images of Tropical Cyclone Iggy as it continues to skirt the coastline of Western Australia. Infrared data from the Atmospheric Infrared Sounder (AIRS) instrument aboard NASA's Aqua satellite showed persistent convection (rising air that forms thunderstorms) around the center, but the center is struggling to consolidate. The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard the same satellite captured a stunning visible image of Iggy at the same time, and showed a well-organized tropical storm.

Although Iggy is not expected to make landfall along the northern coast of Western Australia, forecasters at the Joint Typhoon Warning Center expect Iggy to make landfall in the southern part of the region later during the week of January 30.

Coastal Waters Wind warnings are currently in effect from Kalbarri to Israelite Bay and for Northwest Cape to Coral Bay. High seas warnings are also in effect in those areas.

Tropical Cyclone Iggy has continued moving to the south-southwest at 6 knots (~7 mph/~11 kph). Iggy currently has maximum sustained winds near 55 knots (~63 mph/102 kph)and may strengthen a little over the next day or two as it continues to move parallel to the coastline of Western Australia. Iggy's center was located about 215 nautical miles (247 miles/398 km) west-northwest of Learmonth, Australia, near 20.8 South and 110.5 East.

Tropical Cyclone Iggy is expected to continue on a southwest track over the next 48 hours, before weakening below tropical cyclone intensity on Wednesday night, Feb. 1.

The Joint Typhoon Warning Center forecast expects Iggy to take an eastern turn as it gets pushed by an elongated area of low pressure. Iggy is expected to make landfall on February 3, somewhere near Kalbarri or Northampton, south of Shark Bay.

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






Jan. 27, 2012

MODIS captured a visible image of Tropical Storm Iggy on January 27 at 0655 UTC (2:30 a.m. EST). › View larger image
NASA's Aqua satellite passed over the Southern Indian Ocean and its MODIS instrument captured a visible image of Tropical Storm Iggy on January 27 at 0655 UTC (2:30 a.m. EST). The MODIS instrument captured a true color image of the storm that showed Iggy as a rounded area of clouds.
Credit: NASA Goddard MODIS Rapid Response Team NASA Eyes Cyclone Iggy's Threat to Western Australia

NASA satellites are providing valuable data to forecasters as Tropical Cyclone Iggy nears Western Australia. NASA's Aqua satellite provided visible and infrared data on Iggy, observing colder cloud tops and strengthening storm. Iggy has already triggered warnings and watches along coastal areas.

The Australian Bureau of Meteorology (ABM) has issued a Cyclone Warning for coastal areas from Mardie to Ningaloo including Exmouth and Onslow. ABM has also issued a Cyclone Watch east to Port Hedland and south to Coral Bay. In addition, a Blue Alert has been posted for "People in or near coastal and island communities between Mardie and Coral Bay including the communities of Mardie, Onslow, Exmouth and Coral Bay need to prepare for cyclonic weather."

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard NASA's Aqua satellite captured a true color image of Tropical Storm Iggy on January 27 at 0655 UTC (2:30 a.m. EST), and showed Iggy as a rounded area of clouds with no visible eye. Animated infrared satellite imagery showed a slight cooling of cloud tops in Iggy's main band of thunderstorms, located west of the center. Dropping cloud-top temperatures mean that the strength in the storm is increasing and pushing those cloud tops higher in the atmosphere, where it is colder. Higher cloud tops mean stronger thunderstorms within the tropical cyclone.

At 1500 UTC (10 a.m. EST) on January 27, Iggy's maximum sustained winds were near 55 knots (63 mph/102 kph). Iggy's tropical-storm-force-winds extend 115 nautical miles (132 miles/213 km) from the center. Iggy is about 230 nm (~265 miles/426 km) in diameter. Iggy was centered about 270 nautical miles (~311 miles/500 km) northwest of Learmouth, Australia, near 19.1 South latitude and 110.7 East longitude. Iggy is moving slowly to the south-southeast, toward Western Australia's Pilbara coastline.

ABM classified Iggy as a "Category two" cyclone, with wind gusts of 130 kph (~81 mph). ABM forecasters expect Iggy to become a category three storm on January 28. For updates on tropical cyclone warnings from the ABM, visit: http://www.bom.gov.au/cyclone/.

Because of low wind shear and warm waters, Iggy is expected to continue strengthening on its approach to the Australian coastline. The Joint Typhoon Warning Center forecast as of January 27 takes the center of Iggy's center very close to Learmouth on January 30 and 31 before turning to the southwest and heading back to sea.

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


Jan. 26, 2012

NASA's Aqua satellite passed over Cyclone Iggy (left) on January 26 at 611 UTC (1:11 a.m. EST) › View larger image
When NASA's Aqua satellite passed over Cyclone Iggy (left) on January 26 at 611 UTC (1:11 a.m. EST) the AIRS instrument measured the cloud (purple) top temperatures. Thunderstorm cloud tops around the entire center of circulation were colder than -63 Fahrenheit (-52.7 Celsius) indicating strong storms. The purple area to the far right is from clouds and showers associated with a low pressure area south-southwest of Darwin, Australia.
Credit: NASA/JPL, Ed Olsen NASA Infrared Satellite Instrument Sees Tropical Storm Iggy Growing in Strength

The AIRS infrared instrument that flies on NASA's Aqua satellite has been providing forecasters with the cloud top temperatures in the Southern Indian Ocean's ninth tropical cyclone, which has officially been renamed Iggy. AIRS data showed that the area of strong thunderstorms around Iggy's center has expanded in area over the last day.

The Atmospheric Infrared Sounder (AIRS) instrument provided an infrared snapshot of Iggy's cloud top temperatures on January 26, 2012 at 0611 UTC (1:11 a.m. EST). The AIRS image showed a large and rounded area of high, cold clouds, around the entire center of circulation. The data also showed that strongest convection (rapidly rising air that condenses and forms the thunderstorms that make up the cyclone) is located slightly to the west of the center, because of easterly wind shear. The temperatures of those high cloud tops were colder than -63 Fahrenheit (-51.7 Celsius), which is a threshold scientists use to identify strong thunderstorms with heavy rainfall. This is an indication that Iggy will continue to strengthen.

The AIRS image also showed clouds to the southeast of Iggy that are associated with another low pressure area. That area of disturbed weather is over land and located south-southwest of Darwin.

Iggy is currently located in the Southern Indian Ocean, northwest of Western Australia. At 1500 UTC (10 a.m. EST), Tropical Cyclone Iggy was about 430 nautical miles (~495 miles/~796 km) northwest of Learmonth, Australia, near 16.8 South and 109.0 East. It was moving slowly to the southeast at 5 knots (~6 mph/~9 kph). Iggy's maximum sustained winds are near 45 knots (~52 mph/~83 kph) and it is classified as a tropical storm. Those tropical-storm-force winds extend out to 110 miles (177 km) from the center.

Iggy's approach has prompted the Australian Bureau of Meteorology to issue a cyclone and flood watch. Iggy is moving toward the Pilbara coast. The coastal communities between Whim Creek and Coral Bay will likely experience gusty winds and heavy rainfall on January 27 and 28. Rough surf is also expected along coastal areas including Christmas Island, the Kimberley and Pilbara coasts.

Iggy is forecast to continue strengthening as it moves southeast toward Western Australia. Sea surface temperatures along track are 28 to 29 degrees Celsius (~82 to ~84 Fahrenheit), which the Joint Typhoon Warning Center says is supportive of further development. It is expected to reach cyclone strength before moving to the south.

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


Jan. 25, 2012

Aqua satellite passed over Tropical Storm 09S on January 25 at 7:05 UTC (2:05 a.m. EST) › View larger image
When NASA's Aqua satellite passed over Tropical Storm 09S on January 25 at 7:05 UTC (2:05 a.m. EST) the AIRS instrument measured the temperatures of the low pressure area's cloud tops. Thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius).
Credit: NASA/JPL, Ed Olsen NASA Sees Development of Tropical Storm 09S in Southern Indian Ocean

NASA's Aqua satellite passed over the low pressure system called System 97S on Jan. 24 and observed a large area of strong thunderstorms around its center that hinted at further development. On Jan. 25, the low strengthened into the ninth tropical depression and now a tropical storm of the Southern Indian Ocean.

NASA's Aqua satellite passed over Tropical Storm 09S on January 25 at 7:05 UTC (2:05 a.m. EST), and the Atmospheric Infrared Sounder (AIRS) instrument measured the cloud top temperatures. Just as they appeared in infrared imagery on January 24, thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius). Temperatures that cold indicate uplift (and evaporation) of air is very strong, and it pushes the cloud tops to the top of the troposphere. When cloud tops get that high, they tend to drop heavy rainfall (around 2 inches/50 mm per hour).

AIRS infrared imagery revealed that the convection continues to strengthen and during the early hours on January 25, bands of thunderstorms were developing around the center.

Although Tropical Storm 09S has moved in a westerly direction over the last couple of days, a weather system (elongated area of high pressure, called a ridge) will begin pushing it eastward toward Western Australia late on January 25. The Joint Typhoon Warning Center has forecast Tropical Storm 09S (TS09S) to come closest to the coastline of Western Australia by January 29 and 30, 2012.

At 1500 UTC (10 a.m. EST) on January 25, TS09S had maximum sustained winds near 35 knots (40 mph/~65 kph). It was located near 16.0 South latitude and 107.8 East longitude, about 515 nautical miles (~592 miles/~953 km) northwest of Learmonth, Australia. The storm was still moving to the west at 5 knots (~6 mph/9 kph), but is expected to change course to the east-southeast.

The Joint Typhoon Warning Center expects that Tropical Storm 09S will continue to strengthen over the next couple of days and could reach Cyclone status.

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


Jan. 24, 2012

Aqua satellite passed over System 97S on January 24 at 1:23 a.m. EST › View larger image
When NASA's Aqua satellite passed over System 97S on January 24 at 1:23 a.m. EST the AIRS instrument measured the temperatures of the low pressure area's cloud tops. Thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius).
Credit: NASA/JPL, Ed Olsen NASA Sees Developing Cyclone Near Western Australia

NASA's Aqua satellite saw icy cold cloud top temperatures in the low pressure area called System 97S on January 24, which indicates there's a lot of power in the organizing storm system.

On January 24, 2012, the low pressure area called System 97S was located about 340 miles (~547 km) north-northwest of Learmonth, Western Australia. The Joint Typhoon Warning Center (JTWC) noted that "formation of a significant tropical cyclone is possible within 155 nautical miles (178.4 miles/287 km) either side of a line from 16.6 (South) 112.7 (East) to 17.4 (South) and 107.3 (East) within the next 12 to 24 hours." The center of circulation appears to be near 16.8 South latitude and 112.7 East longitude.

When NASA's Aqua satellite passed over System 97S on January 24 at 06:23 UTC (1:23 a.m. EST) the Atmospheric Infrared Sounder (AIRS) instrument measured the temperatures of the low pressure area's cloud tops. Thunderstorm cloud tops around the entire center of circulation and in some of the bands of thunderstorms that circled the center from northwest to northeast were colder than -63 Fahrenheit (-52.7 Celsius). Those cold temperatures represent strong uplift, hinting System 97S could develop into a tropical depression in the next day or two. AIRS data also showed that System 97S appeared almost symmetrical.

JWTC forecasters noted that the current data on System 97S doesn't justify issuing a tropical depression number yet, but sustained winds are estimated between 28 and 32 knots (~32 to 37 mph / ~52 to 59.6 kph) and just near depression status. System 97S is moving west-southwest at 21 knots (24 mph/~39 kph) away from land. JTWC noted that the likelihood for development into a tropical depression is high.

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