Tropical Cyclone Mahasen  

 

› Larger image
NASA’s Aqua satellite passed over Cyclone Mahasen on May 15 at 07:45 UTC (3:45 a.m. EDT) and showed the western edge of the storm skirting the coast of central India on its way to Bangladesh. Credit: NASA Goddard MODIS Rapid Response TeamNASA Satellites Eye Cyclone Mahasen as Bangladesh Prepares for Landfall

Tropical Cyclone Mahasen has been strengthening and expanding as it moves through the northern Bay of Bengal for a landfall on Thursday, May 16. NASA’s Aqua satellite passed over the cyclone as it was hugging the central India coastline. Rainfall data from NASA’s TRMM satellite was compiled in an animation to reveal large rainfall totals as the storm tracked through the Bay of Bengal earlier this week.

Mahasen is being pushed to the northeast by a trough (elongated area) of low pressure and is expected to make landfall in Bangladesh. BBC News reported on May 15 that an evacuation is under way for hundreds of thousands of residents in coastal areas of Bangladesh. The cyclone is expected to affect low-lying areas of Burma's Rakhine state, where tens of thousands reside in camps.

Although Mahasen is not a strong cyclone, it is large and will generate a storm surge over a large area along the coastline. The storm surge poses the greatest danger to residents of Bangladesh. 

NASA’s Aqua satellite passed over Cyclone Mahasen on May 15 at 07:45 UTC (3:45 a.m. EDT) and the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument captured a visible image of the storm. The MODIS image showed that the storm has expanded over the last several days. In the MODIS image, strong, high thunderstorms are visible north and northeast of the center, as they cast shadows on surrounding storms that make up the cyclone. 

This animated TRMM Multisatellite Precipitation Analysis shows the rainfall that occurred with Tropical Cyclone Mahasen during the week of May 6 through 13, 2013 as it moved through the Bay of Bengal. Rainfall from Mahasen has fallen mainly over the open waters of the northern Indian Ocean and the Bay of Bengal. Rainfall totals of about 500 mm (~19.7 inches) are shown (in red) west of Indonesia in this analysis. Credit: Hal Pierce, SSAI/NASA Goddard

NASA’s Tropical Rainfall Measuring Mission (TRMM) multisatellite Precipitation Analysis was animated at NASA’s Goddard Space Flight Center in Greenbelt, Md. to show the rainfall that occurred with Tropical Cyclone Mahasen during the week of May 6 through 13, 2013. The animation depicted Mahasen as it moved through the Bay of Bengal. The bulk of Mahasen’s rain had fallen mainly over the open waters of the northern Indian Ocean and the Bay of Bengal during that period. The TRMM analysis showed that rainfall totals of about 500 mm (~19.7 inches) fell west of Indonesia in this analysis. 

On May 15 at 0900 UTC (5 a.m. EDT), Cyclone Mahasen’s maximum sustained winds were near 45 knots (51.7 mph/83.3 kph). Mahasen’s center was located near 17.9 north latitude and 88.2 east longitude, about 308 nautical miles (354 miles/570 km) south of Kolkata, India. Mahasen is tracking to the north-northeast at 12 knots (13.8 kph/22.2 kph). 

The exact location of landfall is still uncertain, but using three different computer models, forecasters interpolate between them and have an idea of the general area where Mahasen will hit the coast. The American GFS computer model takes Mahasen the farthest west, the Indian Met Service model brings Mahasen further south, and the U.K. Met Service model takes it even further south, so forecasters are interpolating the storm’s track. 

Warnings are already in effect for Bangladesh. As of 9:51 a.m. EDT (13:51 UTC) on May 15, the Bangladesh Meteorological Department (BMD) issued Danger Signal Number 7 for Chittagong and Cox’s Bazar and Danger Signal Number 5 for Mongla. Because Mahasen is expected to bring very heavy rainfall, the BMD warns that in addition to flooding, landslides are possible in the elevated regions of the Chittagong division. For specifics on the effects for the Danger Signal areas, go to:http://www.bmd.gov.bd/Content.php?MenuId=41&SubMenuId=59. 

All ocean vessels in North Bay have been warned to remain in port or find shelter until further notice. For updates from the Bangladesh Meteorological Department, visit: http://www.bmd.gov.bd/. 

Regardless of where exactly the center comes ashore this is a large cyclone. As a result of its size it is expected to bring a large storm surge above 2 meters, according to the Bangladesh Meteorological Department. So many live a few meters above sea level, which makes them more subject to flooding. 

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

---

May 14, 2013
› Larger image
NASA’s Terra satellite flew over Mahasen on May 14 at 05:35 UTC (1:35 a.m. EDT). The MODIS instrument aboard Terra captured a visible image of the cyclone, revealing that it was a tightly wound, compact storm. Credit: NASA Goddard MODIS Rapid Response Team
› Larger image
NASA’s Aqua satellite flew over Cyclone Mahasen on May 13 at 20:05 UTC (4:05 p.m. EDT) and the Atmospheric Infrared Sounder (AIRS) instrument took the temperature of its cloud tops using infrared light. AIRS showed a large area of strong thunderstorms (purple) around the center of circulation. Credit: NASA JPL/Ed OlsenNASA Satellites See Cyclone Mahasen Make the Curve

Tropical Cyclone Mahasen is moving northward through the Bay of Bengal and is now being pushed by a trough of low pressure, curving the storm’s track to the northeast. NASA’s Terra and Aqua satellites recently captured visible and infrared imagery as the storm began to curve.

NASA’s Aqua satellite flew over Cyclone Mahasen on May 13 at 20:05 UTC (4:05 p.m. EDT) and the Atmospheric Infrared Sounder (AIRS) instrument took the temperature of its cloud tops using infrared light. AIRS showed a large area of strong thunderstorms around the center of circulation where cloud top temperatures were as cold as -63 Fahrenheit (-52 Celsius). The heaviest thunderstorms remained over water and just skirted the southeastern coast of India. 

NASA’s Terra satellite flew over Mahasen on May 14 at 05:35 UTC (1:35 a.m. EDT). The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument aboard Terra captured a visible image of the cyclone, revealing that it was a tightly wound, compact storm. Satellite imagery shows that strong convection has developed around the storm’s center, visible in the MODIS image as high thunderstorm cloud tops that cast shadows on surrounding lower thunderstorms. 

On May 14, Tropical Cyclone Mahasen continues moving through the Bay of Bengal. At 1500 UTC (11 a.m. EDT) Mahasen’s center was near 15.1 north and 86.4 east, about 484 nautical miles (557 miles/896 km) south-southeast of Kolkata, India. Mahasen was moving to the northeast at 7 knots (8 mph/13 kph) and it had maximum sustained winds near 45 knots (51.7 mph/83.3 kph).

Sea surface temperatures in the Bay of Bengal are warm enough to support a tropical cyclone. They are currently near 29 to 30 Celsius (84.2 to 86 Fahrenheit) along the forecast track toward Bangladesh. Vertical wind shear has also decreased, which will allow Mahasen to strengthen over the next couple of days.

Mahasen is forecast to intensify to 70 knots before making landfall near Chittagong, Bangladesh on Thursday, May 16.