image: The area covered by TRMM's Precipitation Radar on March 13, 2012, showed thunderstorm towers in feeder (thunderstorm) bands located to the southwest and northeast of Cyclone Lua's center reached heights of almost 15km (9.3 miles), indicating strong thunderstorms. view more
Credit: NASA/SSAI, Hal Pierce
A tropical storm called Lua formed in the Indian Ocean off Australia's northwestern coast on March 13, 2012. NASA's TRMM satellite passed over Lua and observed moderate rainfall and strong towering thunderstorms within on March 13. By March 14, it was turning back toward Australia and storm warnings had been posted.
The area of Australia where Cyclone Lua is located is sparsely populated, but Lua caused the shutdown of over one quarter of the country's crude oil production.
The Tropical Rainfall Measuring Mission (TRMM) satellite flew over that area on March 13, 2012 at 1622 UTC (12:22 p.m. EDT). A rainfall analysis was conducted at NASA's Goddard Space Flight Center in Greenbelt, Md. using TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments. It was overlaid on an enhanced infrared image from TRMM's Visible and InfraRed Scanner (VIRS) and showed that rainfall intensity was mainly in the moderate range of 20 to 30 mm/hr (~0.8 to 1.2 inches/hr). The area covered by TRMM's Precipitation Radar (PR) did not include Lua's center of circulation but storm towers in feeder bands southwest and northeast of the storm reached to heights of almost 15 km (9.3 miles).
Lua is predicted to circle back toward the northwestern coast of Australia and attain minimal hurricane force winds on March 15, 2012.
On March 14 at 1500 UTC (11 a.m. EDT), Tropical Storm Lua's maximum sustained winds were near 50 knots (57.5 mph/92.6 kph). It was located about 425 nautical miles (489 miles/787 km) northwest of Port Hedland, Australia. It was centered near 15.6 South and 112.9 East. Lua is moving to the northeast near 5 knots (5.7 mph/9.3 kph) but is expected to turn to the southeast and head toward land.
Infrared satellite imagery shows that the strongest convection (rising air that forms thunderstorms that make up the cyclone) is consolidating and strengthening. There is also some drier air moving into the storm's center and easterly vertical wind shear has increased to around 20 knots (23 mph/37.0). Both of those factors are limiting the storm's ability to intensify more. The wind shear is forecast to weaken over the next day, allowing Cyclone Lua to strengthen before it makes landfall.
Forecasters at the Joint Typhoon Warning Center expect the storm to reach peak wind speeds of up to 90 knots (103 mph/168 kph) before landfall and hold together inland as a tropical cyclone all the way to the Gibson Desert.
Currently, communities in Western Australia's Pilbara and Kimberley regions are on alert. Cyclone Lua has now prompted a Cyclone Watch from Cape Leveque to Mardie, Western Australia. According to the latest forecast from the Joint Typhoon Warning Center, Cyclone Lua is moving north, but will turn to the southeast and strengthen into a cyclone before making landfall north of Port Hedland on Friday, March 16.