Featured Images

Text Size

Hurricane Season 2011: Tropical Storm Diane (South Indian Ocean)
02.18.11
 
February 18, 2011

AIRS image of Dianne› View larger image
NASA's AIRS instrument captured this infrared image of a larger, stronger Tropical Cyclone Dianne on Feb. 18 at 06:47 UTC. The purple areas are high, cold thunderstorm cloud tops (-52C/-63F) and areas of heavy rainfall. Credit: NASA JPL/Ed Olsen
NASA See a Stronger, Larger Cyclone Dianne Currently Staying Away from Australia

NASA satellite data appears to have good news today for residents of Western Australia because Cyclone Dianne has moved further away from land, although residents of southwestern Australia should keep an eye on the storm early next week. The same infrared satellite data also indicates that Dianne as strengthened and grown larger since yesterday.

When NASA's Aqua satellite flew over Tropical Cyclone Dianne on Feb. 18 at 06:47 UTC (2:47 p.m. Australia/Perth local time/1:47 a.m. EST) it provided information to forecasters that showed Dianne moving farther west than previously forecast. That movement is keeping the storm farther away from Western Australia and that's good news because Dianne strengthened.

The Atmospheric Infrared Sounder (AIRS) instrument on the Aqua satellite showed a larger area of strong thunderstorms around Dianne's center today, Feb. 18, compared to yesterday. The greatest area of deep convection (rapidly rising air that forms the thunderstorms that power the tropical cyclone) are over the northern semi-circle of the storm.

AIRS infrared data takes temperatures of cloud tops and sea surface temperatures and noticed the stark contrast between the two indicating that the thunderstorm cloud tops were very high, very cold (-52C/-63F) and very strong. Meanwhile, the sea surface temperatures were very warm (warmer than 80F/26.5C) and adding power to Dianne.

Microwave satellite data revealed a small eye in the storm surrounded by bands of thunderstorms.

At 1500 UTC (10 a.m. EST/ 11 p.m. Australia/Perth local time) on Feb. 18, Tropical Cyclone Dianne's maximum sustained winds had increased to 65 knots (74 mph/120 kmh) making her a Category One Cyclone on the Saffir-Simpson scale. Over the weekend, Dianne's maximum sustained winds may reach 105 knots (120 mph/194 kmh) before running into adverse environmental conditions by Monday.

As of today, Dianne has increased in size. Tropical storm-force winds now extend out to 110 miles (177 km) from her center, making her about 220 miles (354 km) in diameter. This corresponds with the larger area of thunderstorms seen by NASA infrared AIRS data today.

Currently, Dianne's center is about 305 miles (490 km) west of Learmonth, Australia near 21.8 South latitude and 108.7 East longitude. Dianne was moving southwest near 9 knots (10 mph/~17 kmh).

By Monday a shortwave trough (elongated area of low pressure) is expected to change Dianne's path to a more southeasterly route. By that time the storm should be in cooler waters and wind shear is forecast to increase. Those are two factors that will help weaken Dianne on her journey southward.

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


February 17, 2011

AIRS image of Dianne› View larger image
This NASA AIRS infrared image of Tropical Storm Dianne from Feb. 17 at 06:05 UTC (1:05 a.m. EST) shows a large area of strong convection and powerful thunderstorms (purple). Those cloud top temperatures in the strongest thunderstorms were as cold as or colder than -63F/-52C. Credit: NASA JPL, Ed Olsen
NASA Infrared Satellite Data Sees an Intensifying Tropical Storm Dianne

Infrared satellite data from NASA's Aqua satellite reveal that Tropical Storm Dianne is getting organized off the coast of Western Australia today.

NASA's Atmospheric Infrared Sounder (AIRS) infrared imagery suggests that Dianne's center of circulation is consolidating and getting organized. There are bands of thunderstorms wrapping into the center of the storm, indicating strengthening is occurring. The AIRS instrument flies aboard NASA's Aqua satellite. The AIRS infrared image of Tropical Storm Dianne from Feb. 17 at 06:05 UTC (1:05 a.m. EST) showed a large area of strong convection and powerful thunderstorms. Those cloud top temperatures in the strongest thunderstorms were as cold as or colder than -63F/-52C.

Microwave imagery from the Advanced Microwave Sounding Unit (AMSU), a multi-channel microwave radiometer installed on meteorological satellites, even indicated that an eye had formed in Dianne's center.

Tropical Storm Dianne is on a southerly track through the Southern Indian Ocean and is currently forecast to stay off shore and away from Western Australia.

At 1500 UTC (10 a.m. EST) Tropical Cyclone Dianne had maximum sustained winds near 55 knots (63 mph/101 kmh). Tropical storm-force winds extend about 60 miles from the center. Dianne was centered about 260 nautical miles (299 miles/281 km) northwest of Learmonth, Australia near 19.0 South and 110.7 East. It was creeping to the southeast at 1 knot (1 mph/2 kmh). Dianne continues to generate waves as high as 19 feet (~6 meters) in that area of the Southern Indian Ocean.

The Joint Typhoon Warning Center (JTWC) expects Dianne to stop meandering and start moving south on Feb. 18 while intensifying. The JWTC does expect that Dianne will remain well west of the Australian coast. However, there are warnings posted for Western Australia. A Cyclone Warning is currently in effect for coastal areas from Exmouth to Coral Bay and a Cyclone Watch is in effect for coastal areas from Onslow to Exmouth and Coral Bay to Overlander Roadhouse, including Carnarvon and Denham.

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


February 16, 2011

AIRS infrared image of Carlos and Dianne› View larger image
NASA's Aqua satellite passed over Australia on Feb. 16 at 05:17 UTC (12:17 a.m. EST/ 2:47 p.m. Australia/Darwin local time). The AIRS instrument on Aqua captured an infrared image of Tropical Storm Dianne (left) and Tropical Storm Carlos (right) and found each to have strong convection (purple) with cloudtop temperatures as cold as -52C. Credit: NASA JPL, Ed Olsen

AIRS visible image of Carlos and Dianne› View larger image
Tropical Storm Dianne (left) is bringing rainfall to Western Australia today and Tropical Storm Carlos (right) is bringing rains and gusty winds to Australia's Northern Territory today. Credit: NASA JPL, Ed Olsen
NASA Sees Tropical Cyclone Double-Trouble for Australia

NASA's Aqua satellite captured an infrared image today of tropical cyclones affecting Australia in the western and northern areas of the country. Newly formed Tropical Storm Carlos is bringing heavy rains and gusty winds to Darwin and the Northern Territory, while Tropical Storm Dianne is bringing rains and winds to Western Australia.

NASA's Aqua satellite passed over Australia today, Feb. 16 at 05:17 UTC (12:17 a.m. EST/ 2:47 p.m. Australia/Darwin local time. The Atmospheric Infrared Sounder (AIRS) instrument captured an infrared image of both tropical storms and found each to have strong convection (rapidly rising air that forms the thunderstorms that power a tropical cyclone). Convection was so strong in Carlos and Dianne that the cloud tops of the thunderstorms within were as cold as or colder than -52 Celsius/ -63 Fahrenheit.

At 0900 UTC (4 a.m. EST/6:30 p.m. Australia/Darwin local time) Tropical Storm Carlos, formerly System 99S, had maximum sustained winds near 35 knots (40 mph/64 kmh) and its center at that time was 15 miles (24 km) south of Darwin, Australia, near 12.7 South and 130.9 East. Eight hours later, by 12 p.m. EST (2:30 a.m. Feb. 17 Australia/Darwin local time), Carlos' center had moved southeast and was inland near Middle Point. Carlos was moving toward the southeast but is expected to turn to the southwest.

Carlos was bringing bands of rainfall to Cape Don, Snake Bay, Cape Fouroroy, and inland over an area that includes Annaburroo, Emerald Springs and Batchelor. For radar from the Australian Bureau of Meteorology, go to: › http://www.bom.gov.au/products/IDR632.loop.shtml.

A Cyclone Warning for Carlos is in effect for coastal areas from Daly River Mouth to Goulburn Island, including Darwin, Croker Island and the Tiwi Islands. A Cyclone Watch continues for coastal areas from Port Keats to Daly River Mouth. The Joint Typhoon Warning Center and Australian Bureau of Meteorology expect Carlos to eventually track southwest over land for the next several days.

Near Western Australia, System 97S intensified into Tropical Storm Dianne overnight. On Feb. 16 at 1500 UTC (10 a.m. EST/12:30 a.m. Feb. 17, Australia/Darwin local time), Tropical Storm Dianne had maximum sustained winds near 40 knots (46 mph / 74 kmh). It was still over open waters in the Southern Indian Ocean, near 18.9 South latitude and 111.3 East longitude, about 250 nautical miles (287 miles/463 km) northwest of Learmonth, Australia.

A Cyclone Watch is currently in effect for coastal areas of Western Australia from Exmouth to Cape Cuvier. During the morning hours (Eastern Time/U.S.) bands of showers were pushing southeast from Dianne from Pardoo (in the east) through Port Hedland southwest to Exmouth. It is currently drifting to the northeast but is expected to loop and move south then southwest after the next day or two.

The Joint Typhoon Warning Center expects Dianne to continue strengthening under an environment of warm sea surface temperatures and low wind shear for the next three days before running into adverse conditions. During that time, however, it is forecast to reach hurricane force and bring gusty winds and heavy rainfall to Learmonth as its center passes to the west.

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


February 15, 2011

AIRS instrument infrared data showed three areas of strong convection (purple) in System 97S. › View larger image
On Feb. 15 at 06:17 UTC (1:17 a.m. EST) AIRS instrument infrared data showed three areas of strong convection (purple) in System 97S. There are three areas of strong thunderstorms and convection (purple) where cloud top temperatures were so high in the atmosphere that they were as cold as or colder than -52 Celsius/-63 Fahrenheit.
Credit: NASA/JPL, Ed Olsen
NASA Satellite Sees Two "Tropical Fists" Threatening Australia

Australia is getting hit with two "tropical fists" as NASA satellites watch two low pressure areas develop near the Northern Territory and Western Australia. System 99S is currently strengthening near Darwin, Australia and another low pressure area called System 97S is strengthening near Western Australia.

System 97S was located about 210 nautical miles north-northwest of Learmonth, Western Australia, at 1800 UTC (1 p.m. EST), Feb. 15. It was centered near 19.2 South and 112.1 East. That puts the center of System 97S well to the northwest of Exmouth. System 97S is forecast to move west or southwest over the next few days.

NASA's Atmospheric Infrared Sounder (AIRS) instrument captured infrared satellite data of System 97S on Feb. 15 at 06:17 UTC (1:17 a.m. EST). AIRS flies onboard NASA's Aqua satellite and the data showed three areas of strong convection in the low pressure area. Those areas of convection appear to be consolidating. Water vapor imagery confirmed that System 97S has rapidly consolidated in the 12 hours before and showed banding of thunderstorms around the southern edge of the center of circulation.

Maximum sustained winds are estimated between 20-25 knots (23 to 29 mph/37 to 46 kmh) and minimum sea level pressure at 1003 millibars.

A Cyclone Watch has been declared for coastal areas from Onslow to Coral Bay. Strong Wind Warnings are in effect from Wallal to Barrow Island, Barrow Island to Northwest Cape, and Northwest Cape to Coral Bay.

The Joint Typhoon Warning Center gives System 97S a good chance of becoming a tropical depression in the next 24 hours. Forecasts currently keep System 97S away from land over the next three days.

For more information about System 99S, visit: www.nasa.gov/hurricane.

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