Hurricane Danielle became the first major hurricane of the 2010 Atlantic hurricane season overnight as it continued to make its way through the central Atlantic.

Danielle, which had been a Category 2 storm the day before with sustained winds estimated at around 95 knots (~110 mph) by the National Hurricane Center, quickly intensified overnight and by morning was a power Category 4 hurricane on the Saffir-Simpson scale with sustained winds of 115 knots (132 mph).

“The TRMM satellite passed directly over Danielle during the night and captured remarkable images as the storm was in the process of intensifying,” said Steve Lang, research meteorologist on the TRMM team in the Mesoscale Atmospheric Processes Branch at NASA’s Goddard Space Flight Center in Greenbelt, Md.

Two images were taken from TRMM at 06:46 UTC (2:46 a.m. EDT) on August 27. The first image showed a top-down view of the horizontal pattern of rain intensity within the storm. Rain rates in the center of the swath are from the TRMM Precipitation Radar (PR), and those in the outer swath are from the TRMM Microwave Imager (TMI).The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS), and are created at NASA Goddard. TRMM is managed by both NASA and the Japanese Space Agency, JAXA.

The  storm known formerly as Tropical Depression 6E, or TD6E, has been downgraded into a remnant low pressure system in the Eastern Pacific Ocean. On July 16 when NASA’s Aqua satellite flew over TD6E, the infrared imagery showed a small area of strong convection in the storm.

The image, captured on July 15 at 2105 UTC 5:05 p.m. EDT was captured when 6E was still a tropical depression. By July 16, 6E was a remnant low pressure area and had maximum sustained winds near 25 knots (28 mph). It was located near 18 North and 111 West hundreds of miles from the southwestern coast of Mexico. 6E was moving west-northwestward near 10 knots (11 mph). The estimated minimum central pressure is 1006 millibars.

On July 16, the National Hurricane Center indicated that scattered moderate isolated strong convection is occurring within 300 nautical miles in the western semicircle. On July 15, NASA infrared imagery showed the strongest convection to the south of the center of circulation.

6E is a large remnant low, about 600 nautical miles in diameter, and is being “stretched” and elongated because of strong vertical wind shear. It’s the wind shear, coupled with dry air and cooler waters (that 6E is moving into) that make strengthening back into a tropical storm very unlikely.