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Hurricane Season 2011: Tropical Cyclone Fina (Southern Indian Ocean)
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TRMM provided a "top down" rainfall analysis of Cyclone Fina on Dec. 23. Light to moderate rainfall, depicted in blue and green is falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour. Heavy rainfall, seen in red was occurring at a rate of 2 inches (50 mm) per hour.
Credit: SSAI/NASA, Hal Pierce
Eastern Australia Under Warnings for "Tropical Cyclone Fina"

When is a cyclone not a cyclone? The answer is when one forecast entity assigns a name to it and another doesn't see it as being that organized. That's the case with the low pressure area called Tropical Cyclone Fina, located off the northeastern coast of Australia. Whatever the name, NASA's TRMM satellite shows it as a large, disorganized, elongated low pressure area with some heavy rainfall on its northern side.

The Australian Bureau of Meteorology (BOM) refers to the low pressure area called System 94S as "Tropical Cyclone Fina" and has issued warnings for Queensland, Australia's eastern coast. The Joint Typhoon Warning Center, a forecast authority for tropical cyclones in the southern Indian Ocean has not yet named the low, and is still referring to it as System 94S because of its disorganized state.

Regardless, warnings and watches are in effect for areas in the Northern Territory and Queensland, Australia. A tropical cyclone warning is in effect from Cape Don to Milingimbi, including Darwin, and a tropical cyclone watch is in effect from Dundee Beach to Cape Don and from Milingimbi to Nhulunbuy. Dangerous surf and abnormally high tides are also forecast for coastal areas of the Wide Bay and Burnett and southeast coast districts.

When the Tropical Rainfall Measuring Mission (TRMM) satellite passed over Tropical Cyclone Fina on Dec. 23 at 0616 UTC (1:16 a.m. EST), it captured a look at rainfall rates happening within the low pressure area. Although it was difficult to pinpoint a center of circulation in the imagery, in what appeared to be a wide band thunderstorms north of the center that contained heavy rain, falling at a rate of 2 inches (50 mm) per hour. Tropical Cyclone Fina also appears to be large in size about 600 nautical miles wide, with the band of heavy rainfall stretching from east to west on the storm's northern side.

On Dec. 23 at 0300 UTC (Dec. 22 at 10 p.m. EST), System 94S or Tropical Cyclone Fina was located near 10.4 South latitude and 130.4 East longitude, or about 120 miles (193 km) north-northwest of Darwin, Australia.

The Joint Typhoon Warning Center (JTWC) noted that the low is elongated, and that there is a low-level low pressure center under an upper-level high pressure area. The wind shear is light and the sea-surface temperatures are warm. However, Fina's maximum sustained winds are estimated between 10 and 15 knots (11 to 17 mph/18 to 27 kmh), not strong enough to be considered by the JWTC as a tropical depression. Winds near the center need to be constantly between 20 and 34 knots (23 and 39 mph/37 and 63 kmh) to meet the criteria. The sea level pressure in Fina is near 1000 millibars.

On Dec. 23, at 7:30 a.m. EST (10 p.m. local time, Darwin, Australia) the Australian Bureau of Meteorology now refers to Fina as an "Ex-tropical cyclone." The latest bulletin stated, "Ex-Tropical Cyclone Fina was situated approximately 450 kilometers (279 miles) east northeast of Sandy Cape and moving in a southeasterly direction. Ex-Tropical Cyclone Fina is expected to continue moving in this direction during the weekend."

Because of the lack of organization and consolidation of the low pressure center within Fina, the JTWC forecast stated that "the potential for the development of a significant tropical cyclone within the next 24 hours remains low." Regardless of what happens with its development, residents along the coast of Queensland, Australia should prepare for some heavy rainfall over the next couple of days.

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