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Hurricane Season 2012: Tropical Cyclone Irina (Indian Ocean)
03.09.12
 
MODIS captured this visible image of Cyclone Irina on March 9 at 1048 UTC (5:48 a.m. EST). › View larger image
The MODIS instrument on NASA's Aqua satellite captured this visible image of Cyclone Irina on March 9 at 1048 UTC (5:48 a.m. EST). The strongest part of the storm is south of the center, and wind shear is now taking a toll on the storm's strength.
Credit: NRL/NASA
NASA Sees Cyclone Irina Weaker in Mozambique Channel

Cyclone Irina has lived a long life and caused a lot of trouble, damages and death over the course of its life, and it appears to be finally fading over the Mozambique Channel.

On March 8 at 1500 UTC (10 a.m. EST), Irina's winds had finally dropped below 45 knots (51.7 mph/83.3 kph) to 35 knots (40.2 mph/64.8 kph) making it a minimal tropical storm. Irina was still in the southern Mozambique Channel, centered near 29.5 South and 37.8 East. That is about 350 miles southeast of Maputo, Mozambique. Irina is moving to the west at 8 knots (9.2 mph/14.8 kph).

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite captured this visible image of Cyclone Irina on March 9 at 1048 UTC (5:48 a.m. EST) that showed the bulk of clouds and showers south of the center of circulation, with some outer bands of thunderstorms to the west.

Infrared satellite imagery shows that the strongest thunderstorms, located in the southeastern quadrant have weakened and are being pushed away from the center from wind shear. Once a tropical cyclone is no longer "stacked" vertically on top of itself, it weakens, and that's what is happening to Irina.

In addition to increased wind shear, sea surface temperatures are below the 80 degree Fahrenheit threshold (26.6 C) needed to maintain a tropical cyclone, so the cooler waters are preventing evaporation and energy feeding into the storm.

The Joint Typhoon Warning Center expects that Irina will finally dissipate at sea over the weekend.

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



Mar. 8, 2012

On March 7 at 5:53 a.m. AIRS data showed that Irina was weakening. › View larger image
When NASA's Aqua satellite passed over Irina on March 7 at 5:53 a.m. EST it captured an infrared image of the storm's cloud top temperatures. AIRS data showed that the coldest (purple) cloud top temperatures (colder than -63F/-52.7C) and strongest convection were south of the center, but they were weakening. The small blue and purple areas over South Africa (left) are likely convective thunderstorms. The darker red color indicates very hot land surface.
Credit: NASA/JPL, Ed Olsen
NASA's Sees Meandering Tropical Storm Irina Still Maintaining Strength

Tropical Storm Irina continues to meander in the southern Mozambique Channel, and NASA's Aqua satellite noticed the strongest convection in the system now appeared tightly wrapped around its center. For the third day in a row, Irina's maximum sustained winds were about the same, but that is expected to change as Irina continues moving through cooler waters.

When NASA's Aqua satellite flew over Irina on Thursday, March 8, 2012 at 11:41 UTC (6:41 a.m. EST), the AIRS instrument captured an infrared view of the storm, as it since its birth last week. The infrared data showed the area with the strongest convection (rapidly rising air that forms the thunderstorms that make up the cyclone) and the coldest, highest cloud tops had become weaker over the last 24 hours. That area of shallow convection was located south of the center of circulation.

On March 8 at 1500 UTC (10 a.m. EST), for the third day in a row, Tropical Cyclone Irina still had maximum sustained winds near 45 knots (~52 mph/83.3 kph). Irina is now about 455 nautical miles (~552 miles/~889 km) east-southeast of Maputo, Mozambique. The center is near 29.4 South latitude and 39.1 East longitude. It is still crawling at 3 knots (3.4 mph/5.5 kph), but is now moving to the southwest. On March 7 it was moving west-northwest and on March 6, it was moving to the east-northeast.

Irina continues moving through cool sea surface temperatures near 25 Celsius/77 Fahrenheit (a tropical cyclone needs temperatures of 22.6C/80F to maintain strength). Irina is expected to weaken and dissipate within a day or so.

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



Mar. 7, 2012

AIRS data showed the bulk of the showers and strongest thunderstorms were on the southern side of the storm. › View larger image
When NASA's Aqua satellite passed over Irina on March 7 at 1053 UTC (5:53 a.m. EST) it captured an infrared image of the storm's cloud top temperatures using the Atmospheric Infrared Sounder (AIRS) instrument. AIRS data showed that the coldest (purple) cloud top temperatures (colder than -63F/-52.7C) that included the bulk of the showers and strongest thunderstorms were on the southern side of the storm.
Credit: NASA/JPL, Ed Olsen
NASA Sees Tropical Storm Irina Heading Back Toward African Mainland

Tropical Storm Irina continues to linger in the Mozambique Channel, and NASA satellite data revealed the strongest storms in the southern quadrant, and Irina is running into some dry air, which may help to weaken it as it moves back to the African mainland.

When NASA's Aqua satellite passed over Irina on March 7 at 1053 UTC (5:53 a.m. EST) it captured an infrared image of the storm's cloud top temperatures using the Atmospheric Infrared Sounder (AIRS) instrument. AIRS data showed that the coldest cloud top temperatures (colder than -63F/-52.7C) that included the bulk of the showers and strongest thunderstorms were still on the southern side of the storm, as they were on March 6.

Infrared imagery revealed a "well-defined low-level circulation center with isolated deep convection flaring," according to the Joint Typhoon Warning Center (JTWC). The JTWC noted that data from the Advanced Microwave Sounding Unit (AMSU) instrument shows "weak deep convective (rising air that forms thunderstorms) banding [of thunderstorms] is limited to the southern quadrant (of the storm) and significant dry air is surrounding the low level center." Dry air can sap the moisture and strength from a tropical cyclone. The AMSU-A instrument is a 15-channel microwave sounder designed primarily to obtain temperature profiles in the upper atmosphere (especially the stratosphere) and provide a cloud-filtering capability for tropospheric temperature observations.

On March 7 at 1500 UTC (10 a.m. EST), Tropical Cyclone Irina had maximum sustained winds near 45 knots (~52 mph/83.3 kph). Irina had not changed in strength in 24 hours as it looped in the southern Mozambique Channel. Irina is now about 480 nautical miles (~552 miles/~889 km) east-southeast of Maputo, Mozambique. The center is near 29.4 South latitude and 39.1 East longitude. It is now crawling to the west-northwest at just 3 knots. Just 24 hours before, Irina was headed east-northeast.

The forecasters at the Joint Typhoon Warning Center stated that Irina is moving through cool sea surface temperatures near 25 Celsius/77 Fahrenheit (a tropical cyclone needs temperatures of 22.6C/80F to maintain strength) and moderate, westerly vertical wind shear." Cool waters and moderate-to-strong wind shear are two factors that weaken tropical cyclones.

Irina is now being steered by a low-level subtropical ridge (elongated area) of high pressure, south of the cyclone. That ridge is pushing Irina to the west. Irina is forecast to continue moving westward at sea over the next couple of days and continue to kick up high waves in the southern Mozambique Channel. Residents along the eastern coast of South Africa and Mozambique should keep an eye on the storm as it moves back in their direction over the next couple of days.

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



Mar. 6, 2012

AIRS showed that bulk of the showers and strongest thunderstorms were on the southern side of Irina. › View larger image
When NASA's Aqua satellite passed over Irina on March 5 at 2211 UTC (5:11 p.m. EST) it captured an infrared image of the storm's cloud top temperatures using the Atmospheric Infrared Sounder (AIRS) instrument. AIRS data showed that the coldest (purple) cloud top temperatures (colder than -63F/-52.7C) that included the bulk of the showers and strongest thunderstorms were on the southern side of the storm.
Credit: NASA/JPL, Ed Olsen
NASA Sees Tropical Cyclone Irina Still Looping at Sea

NASA's Aqua satellite saw Tropical Cyclone Irina making a slow loop in the southern Mozambique Channel for the third day on March 6, 2012. Because of the different weather systems moving through the region, Irina's track has been hard to forecast.

When NASA's Aqua satellite passed over Irina on March 5 at 2211 UTC (5:11 p.m. EST) it captured an infrared image of the storm's cloud top temperatures using the Atmospheric Infrared Sounder (AIRS) instrument. AIRS data showed that the coldest cloud top temperatures (colder than -63F/-52.7C) that included the bulk of the showers and strongest thunderstorms were on the southern side of the storm.

On March 6 at 1500 UTC (10 a.m. EST), Tropical Cyclone Irina had maximum sustained winds near 45 knots (~52 mph/83.3 kph). Irina's strongest winds occurred on March 1, when maximum sustained winds were near 55 knots (~63 mph/~102 kph).

Irina is now about 415 nautical miles (~478 miles/~769 km) southeast of Maputo, Mozambique. The center is near 30.3 South latitude and 39.4 East longitude. It is now moving to the east-northeast. The forecasters at the Joint Typhoon Warning Center noted that Irina is now "slowly weakening within a marginal environment characterized by cool sea surface temperatures near 25 Celsius/77 Fahrenheit (a tropical cyclone needs temperatures of 22.6C/80F to maintain strength) and moderate, westerly vertical wind shear." Cool waters and moderate-to-strong wind shear are two factors that weaken tropical cyclones. Forecasters today at the Joint Typhoon Warning Center are now thinking that those conditions may batter Irina into dissipation in the next day or two, and residents of South Africa and Mozambique are hoping that happens.

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



Mar. 5, 2012

This image from NASA's TRMM satellite shows rainfall in the remnants of Tropical Cyclone Irina on March 5 at 2:23 a.m. local time/South Africa. › View larger image
This image from NASA's TRMM satellite shows rainfall in the remnants of Tropical Cyclone Irina on March 5 at 2:23 a.m. local time/South Africa. Numerous intense storms in the southern and eastern quadrant were dropping rainfall at a rate of over 50mm per hr / ~2 inches (red). Light to moderate rainfall is depicted in blue and green was falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: SSAI/NASA, Hal Pierce

Infrared data from AIRS instrument on NASA's Aqua satellite on March 5 at 1105 UTC showed that most of the strongest thunderstorms and heaviest rainfall (purple) are occurring in the southern half of the storm. › View larger image
Infrared data from AIRS instrument on NASA's Aqua satellite on March 5 at 1105 UTC showed that most of the strongest thunderstorms and heaviest rainfall (purple) are occurring in the southern half of the storm.
Credit: NASA JPL, Ed Olsen
NASA Satellites See Tropical Storm Irina Getting Loopy

Two NASA satellites have been measuring rainfall and cloud top temperatures in Tropical Storm as it has been "going loopy" in the Mozambique Channel over the last couple of days. Irina is making a cyclonic loop, something that a tropical cyclone does on occasion whenever there are a couple of weather systems that push it in different directions.

On March 5, 2012, Irina's maximum sustained winds had increased to near 50 knots (57.5 mph/92.6 kph), , up from 40 knots (46 mph/74 kph) over the last several days. Forecasters at the Joint Typhoon Warning Center expect Irina to strengthen more at sea over the next day, and then begin to weaken.

CURRENT LOCATION

Irina is still centered at sea, and parallel to the middle of South Africa on March 5. Irina's center is about 315 nautical miles south-southeast of Maputo, Mozambique, and it was moving to the southeast, but is expected to start curving to the northeast and then northwest as it continues making a loop that will take it back toward a landfall in extreme northeastern South Africa.

What's making it loop? Weather systems in the area are pushing past Irina, acting as guides for the storm to follow. The last weather system that will turn it back to the north is a ridge (elongated area) of high pressure that's strengthening over South Africa will turn Irina to the northwest.

SATELLITE DATA

Infrared data from Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite showed on March 5, that most of the strongest thunderstorms and heaviest rainfall are occurring in the southern half of the storm. The strongest thunderstorms usually have the highest, and coldest cloud top temperatures, which is what AIRS infrared data reads. When cloud tops exceed the AIRS threshold of -63 Fahrenheit (-52.7 Celsius), the cloud tops are considered strong thunderstorms, and usually they have heavy rainfall. On the northern side of the storm, it's a different story, however, as sinking air on the northern side is preventing thunderstorm development.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite passed over Irina on March 5, 2012 at 0023 UTC (2:23 a.m. local time/South Africa / 7:23 p.m. EST on March 4, EST). A rainfall analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments showed areas of heavy rainfall in several areas, mostly south of the center of circulation. Areas with heavy rain were spotted by the TRMM satellite in the southwestern and eastern quadrants of the storm, and rain was falling at a rate of over 50mm/hr (~2 inches).

LANDFALL

Cyclone Irina is now expected to make landfall in extreme northeastern South Africa, south of the Mozambique border late on March 9, but the forecast could again change as Irina has been slowed by various weather factors. There are several parks located near where landfall is currently forecast. Tembe Elephant Park and the Ndumo Game Reserve are located near the Mozambique border and the Isimangaliso Wetland Park is located to the south. These areas are likely to feel the strongest winds from Irina when it makes landfall.

As Irina nears landfall by the end of the week, cold waters stirred up from below the surface are causing sea surface temperatures near the coast to cool, which will reduce any energy going into Irina as it nears the coast for landfall. Once Irina makes landfall, the forecasters at the Joint Typhoon Warning center expect Irina to dissipate quickly. Meanwhile residents of eastern South Africa, Swaziland and southeastern Mozambique can expect more clouds, showers, gusty winds and rough surf in coastal areas as Irina loops back toward land.

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



Mar. 2, 2012

MODIS captured this image of Irina now over the Mozambique Channel on March 2, 2012 at 1041 UTC. › View larger image
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 a.m. EST). Irina is almost half-way to Mozambique, where it is expected to make landfall early on March 5, 2012.
Credit: NASA Goddard MODIS Rapid Response Team
MODIS captured this image of Irina along the coast of Madagascar on March 1, 2012 at 0130 UTC. › View larger image
NASA's Aqua satellite's MODIS instrument captured this infrared image of Tropical Cyclone Irina still along the coast of Madagascar on March 1, 2012 at 0130 UTC (8:30 p.m. EST, Feb. 29).
Credit: NASA Goddard MODIS Rapid Response Team
NASA Sees Tropical Storm Irina Hit by Wind Shear, Headed for Mozambique

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.


WHY DID IT WEAKEN?

NASA's Aqua satellite's Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of Tropical Cyclone Irina over the Mozambique Channel 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.


WHERE IS IRINA?

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.

NASA 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 microwave imagery 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 band structure 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 landfall 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 infrared satellite imagery 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.


HOW DOES WIND SHEAR AFFECT CYCLONE IRINA?

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 wind shear (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.


CURRENT FORECAST TRACK

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.

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



Mar. 1, 2012

MODIS captured this visible image of Tropical Cyclone Irina on March 1, 2012 at 0715 UTC (2:15 a.m. EST). › View larger image
NASA's Terra satellite's MODIS instrument captured this visible image of Tropical Cyclone Irina hugging the southwestern coast of Madagascar while its center remained over the Mozambique Channel on March 1, 2012 at 0715 UTC (2:15 a.m. EST).
Credit: NASA Goddard MODIS Rapid Response Team
NASA Sees Tropical Storm Irina Still Hugging Madagascar Coast

Satellite imagery from NASA's Terra satellite today, March 1, shows Tropical Storm Irina is slow to leave the coastline of Madagascar.

When NASA's Terra satellite passed over Tropical Storm Irina on March 1 at 0715 UTC (2:15 a.m. EST), the Moderate Resolution Imaging Spectroradiometer aboard captured a visible image of the cyclone. At that time the center of the storm was still over the waters of the Mozambique Channel, but just off the central west coast of Madagascar. The storm's center was near 19.7 South and 43.7 East.

Clouds from the outer reaches of the storm stretched east over the capital city of Antananarivo, although the center was about 225 nautical miles (~259 miles/~417 km) west-northwest of the city and off-shore. Irina had maximum sustained winds near 55 knots (~63 mph/~102 kph) and was moving to the south near 14 knots (16 mph/~26 kph). Tropical-storm-force winds extended out as far as 70 nautical miles (80.5 miles/129.6 km) from the center of the storm.

As Irina continues tracking along the coast, the interaction with land is expected to keep it from strengthening. By March 2, Irina is expected to begin moving away from Madagascar and west into the Mozambique Channel. It is currently moving along the western edge of a low-to-mid level ridge (elongated area) of high pressure (centered east of Madagascar), and will soon be steered west by another building area of high pressure.

The Joint Typhoon Warning Center is forecasting a landfall north of Maputo, Mozambique sometime on March 3. Meanwhile, residents of southwestern Madagascar can expect clouds, gusty winds and rainfall from Irina over the next day or two.

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



Feb. 28, 2012

MODIS captured this visible image of Tropical Cyclone Irina over the Mozambique Channel on February 29, 2012. › View larger image
NASA's Aqua satellite's MODIS instrument captured this visible image of Tropical Cyclone Irina over the Mozambique Channel on February 29, 2012 at 1100 UTC (6 a.m. EST).
Credit: NASA Goddard MODIS Rapid Response Team
AIRS observed that Irina's cloud top temperatures have grown colder, indicating more strength in the storm. › View larger image
On February 29, 2012 at 1100 UTC (6 a.m. EST) the AIRS infrared instrument on NASA's Aqua satellite observed that Irina's cloud top temperatures have grown colder since yesterday, indicating more strength in the storm. North of Irina's center, cloud top temperatures are now colder than -63 Fahrenheit (-52.7C), a threshold in AIRS data that indicates some of the strongest thunderstorms in a tropical cyclone.
Credit: NASA/JPL, Ed Olsen
NASA Satellites See Tropical Cyclone Irina Headed for Mozambique

Visible and Infrared satellite imagery together provide a clearer picture of what a tropical cyclone is doing. NASA's Aqua satellite passed over newly strengthened Cyclone Irene and captured both types of images, which showed the extent and power of the storm.

The low pressure area called System 92S that tracked across northern Madagascar this week and brought flooding rains has moved into the Mozambique Channel, strengthen and has been renamed Irina. NASA satellites captured a visible image of Irina as it filled up the northern half of the Mozambique Channel.

System 92S strengthened into Cyclone Irina off Cape St Andre, Madagascar after moving across the northern half of the country as a soaking low pressure area. Now in the warm waters of the Mozambique Channel (the body of water between the island nation of Madagascar and Mozambique on the African mainland), it is strengthening and moving to the west.

NASA's Aqua satellite's MODIS instrument captured a visible image of Tropical Cyclone Irina over the Mozambique Channel on February 29, 2012 at 1100 UTC (6 a.m. EST). It showed the center of Irina in the northern Mozambique Channel and its clouds extended from Mozambique in the west across the channel to Madagascar.

The Atmospheric Infrared Sounder (AIRS) instrument showed another view of the storm: one in infrared light. Infrared light helps determine temperatures of cloud tops and sea surface temperatures, two factors important in tropical cyclones. Warm sea surface temperatures in excess of 26.6 Celsius (80 Fahrenheit) help maintain a cyclone. The warmer the sea surface, the more energy gets fed (evaporation and moisture) into a tropical cyclone, helping it grow stronger. Sea surface temperatures in the Mozambique Channel are near 29 Celsius (84F), which is helping Cyclone Irina develop and strengthen.

The cloud-top temperatures need to be the opposite of sea surface temperatures to indicate strengthening. The colder the cloud top temperatures, the higher and stronger the thunderstorms are that make up the tropical cyclone (a cyclone/hurricane is made up of hundreds of thunderstorms).

Infrared satellite imagery allows forecasters to see where some of the most powerful thunderstorms are in a tropical cyclone. AIRS infrared data has observed that Irina's cloud top temperatures have grown colder since yesterday, February 28, indicating more strength in the storm. North of Irina's center, cloud top temperatures are now colder than -63 Fahrenheit (-52.7C), a threshold in AIRS data that indicates some of the strongest thunderstorms in a tropical cyclone.

Forecasters at the Joint Typhoon Warning Center (JTWC) using infrared satellite data noted that "Deep convection remains confined along the northern half (of the storm)." Vertical wind shear has been weakening slowly, but is still between 10 and 15 knots (11.5 and 17.2 mph /18.5 and 27.8 kph).

On February 29, 2012 at 1500 UTC (10 a.m. EST), Irina was a tropical storm with maximum sustained winds near 35 knots (~40 mph/~65 kph). It is centered in the Mozambique Channel, about 305 nautical miles northwest of Antananarivo, Madagascar, near 16.2 South and 42.6 East.

JTWC forecasters said today, February 29, that they expect the storm to be strongest between March 2 and March 3 as it moves through the center of the Mozambique Channel. Landfall is expected after 72 hours from 1500 UTC on Feb. 29, which would put it around 1500 UTC (10 a.m. EST) on March 3, 2012 when Irina is forecast to make landfall north of Maputo, Mozambique.

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



Feb. 28, 2012

TRMM shows that intense storms were dropping rainfall at a rate of over 50mm/hr (~2 inches) on February 25, 2012. › View larger image
Rainfall derived from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments shows that numerous intense storms were dropping rainfall at a rate of over 50mm/hr (~2 inches) on February 25, 2012. TRMM Precipitation Radar data also showed that some powerful storms within the area reached to heights of over 15km (~9.3 miles).
Credit: NASA/SSAI, Hal Pierce
TRMM satellite shows rainfall in System 92S on Feb. 25 as it was approaching Madagascar. › View larger image
This image from NASA's TRMM satellite shows rainfall in System 92S on Feb. 25 as it was approaching Madagascar. Numerous intense storms were dropping rainfall at a rate of over 50mm per hr / ~2 inches (red). Light to moderate rainfall is depicted in blue and green was falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: SSAI/NASA, Hal Pierce
TRMM rainfall analysis was made at the Goddard Space Flight Center › View larger image
This TRMM rainfall analysis was made at the Goddard Space Flight Center using data from a near-real time Multi-satellite Precipitation Analysis (TMPA). TRMM-based near-real time Multi-satellite Precipitation Analysis (TMPA) data are used to monitor rainfall over the global Tropics. This analysis shows that during the past week the tropical cyclone contributed to flooding rainfall totaling over 280mm (~11 inches).
Credit: NASA/SSAI, Hal Pierce
AIRS instrument on NASA's Aqua satellite captured this infrared image of System 92S's eastern half › View larger image
On February 28, 2012 at 1011 UTC (5:11 a.m. EST) the AIRS instrument on NASA's Aqua satellite captured this infrared image of System 92S's eastern half, bringing rains to west-central Madagascar. The storm's center is over the waters of the Mozambique Channel and was not in line with the AIRS instrument's view.
Credit: NASA/JPL, Ed Olsen
NASA's TRMM Satellite Measures Heavy Rainfall In Madagascar from System 92S

A weak tropical low pressure area known as System 92S, and locally called Irina caused flooding over northern Madagascar less than two weeks after deadly flooding by Tropical Cyclone Giovanna in the south and central part of the island nation. NASA's TRMM satellite measured System 92S's rainfall over Madagascar, and measured some high rain totals.

System 92S didn't have very strong winds when it passed over the coastal city of Vohemar on Madagascar's northeastern coast over the last couple of days, but street flooding was reported.

A rainfall analysis was made at NASA's Goddard Space Flight Center, Greenbelt, Md. using data from a near-real time Multi-satellite Precipitation Analysis (TMPA). TRMM-based near-real time Multi-satellite Precipitation Analysis (TMPA) data are used to monitor rainfall over the global Tropics. This analysis showed that during the past week the tropical cyclone contributed to flooding rainfall totaling over 280mm (~11 inches).

The TRMM satellite passed over this area on February 25, 2012 at 2025 UTC before this stormy area moved over northeastern Madagascar. Rainfall derived from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) instruments showed that numerous intense storms were dropping rainfall at a rate of over 50mm/hr (~2 inches). TRMM Precipitation Radar data also showed that some powerful storms within the area reached to heights of over 15 km (~9.3 miles).

On February 28, 2012 at 1011 UTC (5:11 a.m. EST) the Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured an infrared image of System 92S's eastern half, bringing rains to west-central Madagascar. The storm's center is over the waters of the Mozambique Channel and was not in line with the AIRS instrument's view. The eastern edge of the storm, however was bringing gusty winds and heavy rainfall to west-central Madagascar.

System 92S filled up the northern half of the Mozambique Channel, stretching from Madagascar in the east, to Mozambique to the west of the channel. Both places were experiencing gusty winds and moderate to heavy rainfall on February 28, as System 92S continues to consolidate and strengthen.

On February 28, 2012, System 92S's center was near 16.1 South and 45.2 East, near the coastline of northwestern Madagascar, but over the waters of the Mozambique Channel. It is moving to the southwest near 7 knots (8 mph/13 kph).

Visible imagery from NASA's Aqua satellite showed the bulk of System 92S's clouds were pushed to the west of its center, as a result of wind shear. Because water vapor imagery revealed a lot of moisture over the Mozambique Channel, and the sea surface temperatures are well over the 26.6C (80F) threshold needed to maintain a tropical cyclone, conditions are improving for further development. Wind shear is also expected to ease, which will help with further intensification as System 92S moves further into the Mozambique Channel.

The Joint Typhoon Warning Center gives System 92S a high chance for becoming a tropical depression in the next 24 hours.

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
































Feb. 27, 2012

AIRS captured developing System 92S in the Indian Ocean on February 25 at 0941 UTC. › View larger image
The AIRS instrument on NASA's Aqua satellite captured infrared imagery on developing System 92S in the Mozambique Channel (Indian Ocean). On February 25 at 0941 UTC, System 92S was moving west toward Madagascar. By February 26 at 10:23 UTC System 92S was over northwestern Madagascar. On February 27 at 1105 UTC had moved into the Mozambique Channel and appeared to be heading for a landfall in Mozambique.
Credit: NASA/JPL, Ed Olsen
A visible image of System 92S was also captured by AIRS on February 27. › View larger image
This visible image of System 92S was also captured from the AIRS instrument on NASA's Aqua satellite on February 27. System 92S's center is now over the Mozambique Channel.
Credit: NASA/JPL, Ed Olsen
Three Days of NASA Infrared Images Show System 92S Tropically Developing

NASA satellites have been watching the low pressure area called System 92S for days, and infrared imagery from NASA's Aqua satellite showed cloud temperatures were cooling, indicating the storm was getting more organized as it moved over northern Madagascar. Now it may be headed for landfall in Mozambique.

The Atmospheric Infrared Sounder (AIRS) instrument on NASA's Aqua satellite captured infrared imagery on developing System 92S as it moved from the Southern Indian Ocean, west across northern Madagascar and into the Mozambique Channel. On February 25 at 0941 UTC, System 92S appeared as a rounded low pressure area with the strongest storms (and highest, coldest cloud tops on AIRS infrared imagery) south of the center of circulation. It was still in the open waters of the Southern Indian Ocean and was moving west toward Madagascar. By February 26 at 10:23 UTC System 92S was raining on northern Madagascar. On February 27 at 1105 UTC had moved into the Mozambique Channel and appeared to be heading for a landfall in Mozambique. On the 27th, the strongest thunderstorms and coldest cloud tops appeared in two areas, north and east of the storm's center.

On February 27, the center of System 92S was located in the Mozambique Channel, near 13.5 South and 48.5 East, about 345 nautical miles north-northeast of Antananarivo, Madagascar. AIRS infrared imagery indicated that the low had weakened because of its interaction with land, as it moved over northern Madagascar.

Now that the center of System 92S is over the warm waters of the Mozambique Channel, it is expected to redevelop quickly. The area of strong thunderstorms east of center, as seen on AIRS imagery is a band of thunderstorms.

The Joint Typhoon Warning Center gives this system a high chance for developing further into a tropical cyclone in the next 24 hours.

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