NASA sees tropical storm Irina hit by wind shear, headed for Mozambique

Mar 02, 2012
NASA's Aqua satellite's MODIS instrument captured this infrared image of Tropical Cyclone Irina now over the Mozambique Channel on March 2, 2012 at 1041 UTC (5:41 am EST). Irina is almost half-way to Mozambique, where it is expected to make landfall early on March 5, 2012. Credit: Credit: NASA Goddard MODIS Rapid Response Team

The AIRS instrument on NASA's Aqua satellite provided forecasters with an infrared look at what was happening "under the hood" of Tropical Storm Irina's clouds and saw two reasons why it temporarily weakened before moving into the Mozambique Channel and heading for landfall in Mozambique in a couple of days.


NASA's Aqua satellite's Atmospheric Infrared Sounder (AIRS) instrument captured an of Tropical Cyclone Irina over the on March 1, 2012 at 0130 UTC (8:30 p.m. EST, Feb. 29). At that time, the strongest thunderstorms were around the center of circulation and had become much smaller in area and displaced from the center as a result of interaction with the land of southwestern Madagascar and wind shear, respectively.


On March 2, 2012 at 1500 UTC (5 p.m. local time) the center of Irina was in the Mozambique Channel, almost half-way to Mozambique. The distance between Toliara, Madagascar and Maputo, Mozambique across the channel is 719 miles (1,158 km). It was located 425 nautical miles (489 miles/787 km) northeast of Maputo, Mozambique, near 24.5 South and 39.6 East.

AIRS scientist Ed Olsen at NASA's Jet Propulsion Laboratory in Pasadena, Calif. looked at the last two days of satellite imagery. Olsen said, "If you compare the satellite from the Aqua satellite's ascending pass of March 2 with that from descending pass of March 1, you can see that the strongest convection cell (which was just on the west coast of Madagascar) has disappeared. Also, the rain has also disappeared. However, on March 2 you see a strengthening convection cell in the Mozambique Channel at about 41 East, 25 South. This may be the indication of the final intensification before in Mozambique. The structure of the storm is very asymmetrical and there is no 'warm core,' which would indicate strong convection in the circulation center."

NASA AIRS on March 2 showed Irina's low-level circulation center is now partially exposed to outside winds, making it open for weakening by wind shear. Olsen said that the infrared satellite data agrees with the microwave satellite data, and shows the main area of showers and thunderstorms are now southeast of the center, which means that wind shear from the northwest are taking a toll.


Think of a cyclone as a haystack. Its circular winds are "stacked" up on top of each other at different heights in the atmosphere. When wind shear enters the picture, it's like having a giant fan blowing at one height, say the middle of the haystack. When that happens, the haystack, like the tropical cyclone cannot support itself and becomes structurally weaker. That's what has happened with Irina today. However, wind shear is expected to wane in the next two days.

Maximum sustained winds are currently near 50 knots (~58 mph/~93 kph), weaker than yesterday because of the storm center's close proximity to the southwestern coast of Madagascar and because it drifted closer to an area of higher (up to 20 knots/23 mph/37 kph).

However, Irina continues moving away from the coast at 17 knots (~20 mph/~32 kph), so it is expected to intensify because of the warm waters in the Mozambique Channel over the next day or two. Irina is expected to intensify slightly, but remain a tropical storm until it makes landfall.


Irina is expected to begin affecting coastal Mozambique before 1200 UTC (2 p.m. Local time, Mozambique) on March 3, with rough surf, gusty winds and moderate to heavy rainfall. Irina is currently creating seas of 20 feet (~6 meters) in the southern Mozambique Channel, and those rough seas that will affect the Mozambique coast.

The Joint Typhoon Warning Center forecasts Irina to track along the southeastern coast from Inhambane, Quissico, Chibuto and move inland just north of Maputo by March 5 at 0000 UTC (just after midnight local time on March 5) so it will be an overnight landfall. It is then expected to move west-southwest and dissipate quickly over Mozambique.

Explore further: Magnitude-7.2 earthquake shakes Mexican capital

add to favorites email to friend print save as pdf

Related Stories

Recommended for you

Magnitude-7.2 earthquake shakes Mexican capital

Apr 18, 2014

A powerful magnitude-7.2 earthquake shook central and southern Mexico on Friday, sending panicked people into the streets. Some walls cracked and fell, but there were no reports of major damage or casualties.

User comments : 0

More news stories

China says massive area of its soil polluted

A huge area of China's soil covering more than twice the size of Spain is estimated to be polluted, the government said Thursday, announcing findings of a survey previously kept secret.

UN weather agency warns of 'El Nino' this year

The UN weather agency Tuesday warned there was a good chance of an "El Nino" climate phenomenon in the Pacific Ocean this year, bringing droughts and heavy rainfall to the rest of the world.

NASA's space station Robonaut finally getting legs

Robonaut, the first out-of-this-world humanoid, is finally getting its space legs. For three years, Robonaut has had to manage from the waist up. This new pair of legs means the experimental robot—now stuck ...

Ex-Apple chief plans mobile phone for India

Former Apple chief executive John Sculley, whose marketing skills helped bring the personal computer to desktops worldwide, says he plans to launch a mobile phone in India to exploit its still largely untapped ...

Filipino tests negative for Middle East virus

A Filipino nurse who tested positive for the Middle East virus has been found free of infection in a subsequent examination after he returned home, Philippine health officials said Saturday.

Egypt archaeologists find ancient writer's tomb

Egypt's minister of antiquities says a team of Spanish archaeologists has discovered two tombs in the southern part of the country, one of them belonging to a writer and containing a trove of artifacts including reed pens ...