Gaja (Southern Indian Ocean)

November 16, 2018 – NASA Catches Tropical Cyclone Gaja’s Landfall

Caught in the act of landfall, Tropical Cyclone Gaja was seen by NASA’s Aqua satellite as it passed overhead and collected temperature information.

AIRS image of Gaja
NASA’s Aqua satellite provided an infrared picture of Tropical Cyclone Gaja’s cloud top temperatures from Nov. 15 at 3:29 p.m. EDT (2029 UTC). Gaja’s center was making landfall along the coast of southeastern India. Coldest clouds tops and strongest storms appear in purple. Credit: NASA JPL, Heidar Thrastarson

The Atmospheric Infrared Sounder or AIRS instrument aboard NASA’s Aqua satellite passed over Tropical Cyclone Gaja on Nov. 15 at 3:29 p.m. EDT (2029 UTC) and analyzed the storm in infrared light. Infrared light provides temperature data and that’s important when trying to understand how strong storms can be. The higher the cloud tops, the colder and the stronger they are.

When Aqua passed over the Indian Ocean, Gaja’s center was making landfall along the coast of southeastern India. The AIRS instrument found coldest cloud top temperatures in thunderstorms around the center, where temperatures were as cold as minus 63 degrees Fahrenheit (minus 53 degrees Celsius). Storms with cloud top temperatures that cold have the capability to produce heavy rainfall.

At 10 a.m. EST (1500 UTC), the center of Tropical Cyclone Gaja was located near latitude 9.7 degrees north and longitude 75.9 degrees west. Gaja was moving toward west-southwest. Maximum sustained winds are near 46 mph (40 knots/74 kph) with higher gusts.

Gaja was exiting the southwestern coast of India on Nov. 16 at 7 a.m. EST (1200 UTC) and was moving into the Arabian Sea where it is expected to maintain strength and travel in a westerly direction over the next several days.

By Rob Gutro
NASA’s Goddard Space Flight Center

Gaja (Southern Indian Ocean)

Nov. 15, 2018 – NASA Finds a Cloud-Filled Eye in Tropical Cyclone Gaja

Tropical Cyclone Gaja continued to organize in the Bay of Bengal as it made its approach to southeastern India when NASA-NOAA’s Suomi NPP satellite passed overhead and captured an image. The image revealed that Gaja had developed a cloud-filled eye.

Suomi NPP image of Gaja
On Nov. 15, the VIIRS instrument aboard NASA-NOAA’s Suomi NPP satellite captured a visible image of Tropical Storm Gaja in the Bay of Bengal approaching southern India (left). Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

The Bay of Bengal is in the Northern Indian Ocean basin, east of India.

On Nov. 15, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite took a visible light image of Tropical Storm Gaja. It revealed what appeared to be a cloud-filled eye. The Joint Typhoon Warning Center confirmed that “animated multispectral satellite imagery shows a more compact system with a dimple feature on the central convection – indicative of a formative eye.”

On Nov. 15 at 10 a.m. EDT (1500 UTC) Gaja’s maximum sustained winds were near 55 knots (63 mph/102 kph), but weakening is expected as it nears the coast of southeastern India. Gaja was located near 10.8 degrees north latitude 80.7 east longitude. It was about 145 nautical miles south-southeast of Chennai, India.

The Joint Typhoon Warning Center or JWTC noted that Gaja will move west-southwest and is approaching landfall near Cuddalore before Nov. 16 at 4 a.m. EDT (0900 UTC). After crossing southern India, the storm will re-strengthen in the Arabian Sea, before dissipating after 5 days.

By Rob Gutro
NASA’s Goddard Space Flight Center

Gaja (Southern Indian Ocean)

Nov. 14, 2018 – Tropical Cyclone Gaja Approaching Southeastern India

Tropical Cyclone Gaja continued to track toward a landfall in southeastern India when NASA-NOAA’s Suomi NPP satellite flew over the Bay of Bengal and provided a visible image of the storm.

Suomi NPP image of Gaja
NASA-NOAA’s Suomi NPP satellite passed over the Northern Indian Ocean and captured a visible image of Tropical Cyclone Gaja approaching the southeastern coast of India at 2:36 a.m. EDT (0736 UTC) on Nov. 14, 2018. Credit: NASA/NOAA/NRL

Suomi NPP passed over Gaja on Nov. 14 at 2:36 a.m. EDT (0736 UTC) and the VIIRS instrument provided a visible image. The VIIRS image showed Gaja appeared more organized than the previous day as powerful thunderstorms circled the center. A thick band of thunderstorms wrapped into the low level center from the eastern quadrant.

At 4 a.m. EDT (0900 UTC) Tropical Cyclone Gaja was located near 12.6 degrees north latitude and 84.5 degrees east longitude. That’s about 623 nautical miles south-southwest of Calcutta, India. Gaja is moving to the west-southwest and has maximum sustained winds near 45 knots (52 mph/83 kph).

The Regional Specialized Meteorological Center for Tropical Cyclones over the Northern Indian Ocean or RSMC has issued a tropical storm warning for southern India. For updates visit: http://www.rsmcnewdelhi.imd.gov.in/index.php?lang=en

The Joint Typhoon Warning Center or JTWC forecasters expect Gaja to track over the southern Indian Peninsula, where may likely hold together and reach the Arabian Sea.

By Rob Gutro 
NASA’s Goddard Space Flight Center

Gaja (Southern Indian Ocean)

Nov. 13, 2018 – NASA-NOAA Satellite Finds a Large Tropical Cyclone Gaja

NASA-NOAA’s Suomi NPP satellite passed over the Bay of Bengal, Northern Indian Ocean and captured a visible image of Tropical Cyclone Gaja.

Suomi NPP Image of Gaja
On Nov.13, the VIIRS instrument aboard NASA-NOAA’s Suomi NPP satellite captured a visible image of Tropical Cyclone Gaja in the Northern Indian Ocean. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

Gaja formed on Nov. 10 at 4 p.m. EST (2100 UTC) as tropical cyclone 07B, about 569 miles south-southwest of Chittagong, Bangladesh. It strengthened into a tropical storm and was renamed Gaja.

On Nov. 13, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite gathered data on Tropical Cyclone Gaja. Gaja appeared somewhat elongated and had bands of thunderstorms wrapping into the center. Gaja appeared to extend over much of the Bay of Bengal in satellite imagery.

The Joint Typhoon Warning Center or JTWC noted “animated multispectral satellite imagery shows expansive but disorganized and fragmented rain bands loosely wrapping into an obscured low level circulation with the deep central convection sheared northeastward.”

On Nov., 13 at 10 a.m. EST (1500 UTC) Gaja’s maximum sustained winds were near 40 mph (35 knots/62 kph). It was located approximately 320 nautical miles east of Chennai, India near 13.4 degrees north latitude and 85.6 degrees east longitude. Gaja was moving west-southwest.

JTWC forecasters expect a slow intensification, peaking at 50 knots (57.5 mph/92.6 kph) by landfall in southern India just south of Chennai on Nov. 15.

By Rob Gutro
NASA’s Goddard Space Flight Center

Bouchra (Southern Indian Ocean)

Nov. 13, 2018 – NASA-NOAA Satellite Catches Short-Lived Tropical Cyclone Bouchra

Tropical Cyclone Bouchra formed on Nov. 10 in the Southern Indian Ocean and was already on its way to dissipation when NASA-NOAA’s Suomi NPP satellite passed overhead on Nov. 13.

Suomi NPP Image of Bouchra
On Nov.13, the VIIRS instrument aboard NASA-NOAA’s Suomi NPP satellite captured a visible image of Tropical Cyclone Bouchra in the Southern Indian Ocean. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

Bouchra formed on Nov. 10 around 4 a.m. EDT (0900 UTC) about 220 miles northwest of Cocos Island, near 5.5 degrees south latitude and 90.7 east longitude. It was the fourth tropical cyclone of the Southern Indian Ocean cyclone season.

On Nov. 13, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard NASA-NOAA’s Suomi NPP satellite analyzed Tropical Depression Bouchra showed a disorganized storm. The Joint Typhoon Warning Center noted the storm appeared to have “shallow disorganized central convection sheared eastward, partly exposing a weak and ragged low level circulation.”

Wind shear was stretching the storm out from west to east. In general, wind shear is a measure of how the speed and direction of winds change with altitude. Winds at different levels of the atmosphere pushed against the cylindrical circulation center and skewed it, weakening the rotation.

On Nov., 13 at 4 a.m. EDT (0900 UTC) Bouchra’s maximum sustained winds had dropped to 34.5 mph (30 knots/55.5 kph). It was located approximately 495 nautical miles northwest of Cocos Island near 7.2 degrees south latitude and 90.3 degrees east longitude. Bouchra was moving southeastward, and will dissipate later in the day.

By Rob Gutro
NASA’s Goddard Space Flight Center

Alcide (Southern Indian Ocean)

Nov. 13, 2018 – NASA Analyzed Tropical Cyclone Alcide’s Rainfall Before Dissipation

Tropical Cyclone Alcide dissipated over the weekend of Nov. 11 and 12 in the Southern Indian Ocean.

GPM image of Alcide
On Nov. 8, when Tropical Cyclone Alcide was at peak intensify, Data collected by the GPM core satellite revealed that the powerful tropical cyclone was producing extremely heavy rainfall. GPM’s radar (DPR Ku Band) indicated that tall convective storms in the northwestern side of Alcide’s eyewall were dropping rain at a rate of more than 255 mm (10 inches) per hour. In tropical cyclone Alcide’s western eye wall. A few of these tall storms were found by GPM to reach heights above 16.0 km (9.92 miles). Credit: NASA/JAXA, Hal Pierce

However, when it was near peak intensity, the Global Precipitation Measurement mission or GPM core satellite provided a look at the rain falling within.

The GPM core observatory satellite, a joint mission between NASA and the Japan Aerospace Exploration Agency, JAXA, had an excellent view of tropical cyclone Alcide on November 8, 2018 at 10:59 a.m. EDT (1559 UTC)  after it had moved to a location northeast of Madagascar. At that time Alcide had reached its peak intensity with winds of about 95 knots (109 mph) making it the equivalent of a strong category two hurricane on the Saffir-Simpson hurricane wind scale.

Data collected by GPM’s Microwave Imager (GMI) and GPM’s Dual-Frequency Precipitation Radar (DPR) instruments revealed that the powerful tropical cyclone was producing extremely heavy rainfall. GPM’s radar (DPR Ku Band) indicated that tall convective storms in the northwestern side of Alcide’s eyewall were dropping rain at a rate of more than 255 mm (10 inches) per hour.

GPM’s radar data (DPR Ku Band) were used to create an image to probe the 3D structure of precipitation within tropical cyclone Alcide.  The well-defined eye of the powerful tropical cyclone is revealed with this simulated view from the southwest.  GPM’s DPR found that the most powerful convective storms were located in tropical cyclone Alcide’s western eye wall. A few of these tall storms were found by GPM to reach heights above 16.0 km (9.92 miles).

On Nov. 11, Tropical cyclone Alcide dissipated near 12.3 south latitude and 51.9 east longitude, about 529 miles north-northwest of St Denis, La Reunion.

By Rob Gutro / Hal Pierce
NASA’s Goddard Space Flight Center

Alcide (Southern Indian Ocean)

Nov. 09, 2018 – NASA Satellite Sees Tropical Cyclone Alcide Nearing Madgascar

Tropical Cyclone Alcide continued to linger just northeast of the Island nation of Madagascar in the Southern Indian Ocean when NASA’s Aqua satellite passed overhead and captured an image of the storm.

Aqua image of Alcide
On Nov. 9 the MODIS instrument aboard NASA’s Aqua satellite captured a visible image of Tropical Cyclone Alcide in the Southern Indian Ocean, located northeast of Madagascar. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

On Nov. 9 the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Aqua satellite provided a visible light image of the storm. The MODIS image showed a somewhat elongated storm from northwest to southeast with the bulk of clouds in the western quadrant of the storm.

On Nov. 9, the Joint Typhoon Warning Center or JTWC noted that animated multispectral satellite imagery showed that Alcide has lost much of its deep convection (rising air that forms the thunderstorms that make up a tropical cyclone) but maintained its spiral banding, and convection is newly flaring over the low level circulation center.

On Nov. 9 at 10 a.m. EST (1500 UTC), Alcide’s maximum sustained winds had dropped to 80 mph (70 knots/129.6 kph). It was located approximately 487 nautical miles north-northwest of Port Louis, Mauritius. Alcide is moving southward at 1.1 mph (1 knot1.8 kph) and is expected to curve to the northwest.

Because of the storm’s slow movement, it is bringing up cooler waters from below the ocean’s surface, which will in turn, weaken the storm.

The Joint Typhoon Warning Center now expects Alcide to move to the northwest and pass just north of the northern point of Madagascar over the next several days.

By Rob Gutro
NASA’s Goddard Space Flight Center

Alcide (Southern Indian Ocean)

Nov. 08, 2018 – Tropical Cyclone Alcide’s Rainfall Observed By GPM Satellite

The Global Precipitation Measurement mission or GPM core satellite passed over the Southern Indian Ocean and analyzed the rainfall occurring in pre-season Tropical Cyclone Alcide.

GPM image of Alcide
On Nov. 6, the GPM core satellite showed strong convective storms northwest of Alcide’s center of circulation were dropping rain at a rate of more than 44 mm (1.73 inches) per hour. Credit: NASA/JAXA, Hal Pierce

Tropical cyclone Alcide (03S), the first tropical cyclone of the 2018-2019 South-West Indian Ocean tropical cyclone season, has formed in the South Indian Ocean northeast of Madagascar. The Joint Typhoon Warning Center (JTWC) issued its first warning for 03S on Nov. 6, 2018 at 0000 UTC (Nov. 5 at 7 p.m. EST) when the tropical cyclone was located about 1,313 km (709 nautical miles) west of Diego Garcia.  This is a little early for a tropical cyclone to develop in that part of the world. The South-West Indian Ocean tropical cyclone season doesn’t officially begin until November 15, 2018.

The GPM core observatory satellite had a good view of tropical cyclone Alcide on November 6, 2018 at 11:09 a.m. EST (1609 UTC). At that time Alcide had maximum sustained winds of about 35 knots (40.3 mph). GPM’s Microwave Imager (GMI) and GPM’s Dual-Frequency Precipitation Radar (DPR) instruments collected data that showed the location and intensity of precipitation within Alcide. GPM’s GMI indicated that strong convective storms northwest of Alcide’s center of circulation were dropping rain at a rate of more than 44 mm (1.73 inches) per hour.  GPM’s radar (DPR Ku Band) probed Alcide in a swath through the eastern side of the tropical cyclone. Those data revealed the locations of precipitation within feeder bands spiraling into the southeastern side of the intensifying tropical cyclone.


On Nov. 6, the GPM core satellite showed strong convective storms northwest of Alcide’s center of circulation were dropping rain at a rate of more than 44 mm (1.73 inches) per hour.   Credit: NASA/JAXA, Hal Pierce

At NASA’s Goddard Space Flight Center in Greenbelt, Maryland, a 3D animation was created from the data that showed a simulated flyby above Tropical Cyclone Alcide. Measurements of the relative heights of precipitation within tropical cyclone Alcide were made possible using GPM’s radar data (DPR Ku Band). DPR’s Ku Band radar enables three dimensional measurements of precipitation within a 152 mile (245 km) wide swath. The heights of precipitation over a larger area were estimated by blending measurements from GPM’s radar (DPR Ku band) with heights based on the Meteosat satellite’s infrared temperatures. GPM is a joint mission between NASA and the Japan Aerospace Exploration Agency, JAXA.

On Nov. 8 at 10 a.m. EST (1500 UTC), Alcide had achieved peak wind speed when maximum sustained winds were near 95 knots (110 mph/178 kph). A weakening trend is now expected, according to the JTWC. Alcide was centered near 12.1 degrees south latitude and 53.6 degrees east longitude, about 528 nautical miles north-northwest of Port Louis, Mauritius. Alcide was moving to the southwest.

Satellite data on Nov. 8 showed that the eye had become ragged and cloud-filled.

The JTWC forecast calls for Alcide to loop.  Alcide is expected to remain well northeast of Madagascar.  Alcide is then expected to move into an area of increasing vertical wind shear and lower sea surface temperatures causing the tropical cyclone to gradually weaken.

By Harold F. Pierce / Rob Gutro
NASA Goddard Space Flight Center

Alcide (was 03S – Southern Indian Ocean)

Nov. 07, 2018 – NASA Sees Tropical Cyclone Alcide Reach Hurricane Strength

NASA’s Terra satellite provided a visible image of a more organized Tropical Cyclone Alcide in the Southern Indian Ocean after it reached hurricane-force.

Terra image of Alcide
On Nov. 7, the MODIS instrument aboard NASA’s Terra satellite provided a visible image of Tropical Cyclone Alcide in the Southern Indian Ocean after it strengthened to hurricane-force. Credit: NASA Worldview, Earth Observing System Data and Information System (EOSDIS)

On Nov. 7, a visible image of Alcide taken by the Moderate Resolution Imaging Spectroradiometer or MODIS instrument aboard NASA’s Terra satellite showed an organized storm with a thick band of powerful thunderstorms circling the center. The eye appears ragged on the MODIS imagery and is about 10 nautical miles wide. Satellite data taken after the MODIS image showed that the system continued to strengthen.

The Joint Typhoon Warning Center said that at 10 a.m. EST (1500 UTC) on Nov. 7, Alcide had maximum sustained winds near 75 knots (86 mph/139 kph). It was centered near 10.6 degrees south latitude and 55.7 degrees east longitude. Tropical cyclone Alcide is located approximately 587 nautical miles north of Port Louis, Mauritius, and was moving to the west-southwest.

Alcide is expected to strengthen over the next day or two before starting a weakening trend over cooler ocean waters.

By Rob Gutro
NASA’s Goddard Space Flight Center

03S (Southern Indian Ocean)

Nov. 06, 2018 – Satellite Finds Tropical Cyclone 03S Develop in Southern Indian Ocean

Tropical Cyclone 03S formed in the Southern Indian Ocean and the NOAA-20 satellite passed overhead and captured a visible image of the storm.

JPSS image of 03S
At 5:12 a.m. EDT (0912 UTC) on Nov.6, the VIIRS instrument aboard NOAA’s NOAA-20 satellite captured a visible image of Tropical Cyclone 03S in the Southern Indian Ocean Credit: NASA/NRL

At 5:12 a.m. EDT (0912 UTC) on Nov.6, the Visible Infrared Imaging Radiometer Suite (VIIRS) instrument aboard the NOAA-20 polar orbiting satellite saw fragmented bands of thunderstorms around Tropical Storm 03S’s center of circulation. The VIIRS image revealed that the bulk of clouds and storms were south of the center. The Joint Typhoon Warning Center noted “The bulk of the deep convection remains concentrated southwestward of the low level circulation.”

On Nov. 6 at 11 a.m. EDT (1500 UTC) 03S’s maximum sustained winds were near 35 knots (40 mph/62 mph) making it a tropical storm. It was located approximately 641 nautical miles north of Port Louis, Mauritius near 9.7 south latitude and 58.9 east longitude. 03S was moving west-southwestward and is expected to strengthen over the next several days.

NOAA-20 is the first in the JPSS series of satellites. JPSS is a collaborative program between the National Oceanic and Atmospheric Administration (NOAA) and its acquisition agent, the National Aeronautics and Space Administration (NASA). NOAA is responsible for managing and operating the JPSS program, and developing portions of the ground segment, while NASA is responsible for developing and building the JPSS instruments, spacecraft, and portions of the ground segment and providing launch services.

For more information about the JPSS series of satellites, visit: https://www.jpss.noaa.gov/

By Rob Gutro
NASA’s Goddard Space Flight Center