Dissecting Sandy and Imaging the Hybrid Storm

Atlantic tropical storms mostly tear through the Caribbean and the Gulf of Mexico, and lose energy as they pass over the U.S mainland. However, Hurricane Sandy crept along the Eastern Seaboard, where waters that were warmer than usual for this time of year and that kept the storm alive and kicking. As the storm moved northward, it became a hybrid storm, drawing strength from the differential between the storm's warm air and cold northern air from the jet stream.

And why Sandy took a turn? Sandy took a left turn, which set it for a direct and perpendicular strike on the coast. This turn was because a cold front on the mainland sucked the storm westward, while the current state of a weather pattern known as the North Atlantic Oscillation is blocking the storm from heading eastward.

Hurricane Sandy came in late into the Atlantic hurricane season and it interacted and merged with much colder air moving in from the north. Due to this reason the storm became a combination of weather systems and the technology to monitor these kinds of storms is relatively not advanced.

NASA's Tropical Rainfall Measuring Mission, or TRMM satellite, can measure rainfall rates and cloud heights in tropical cyclones, and was used to create an image to look into Hurricane Sandy on Oct. 28, 2012. Owen Kelly of NASA's Goddard Space Flight Center in Greenbelt, Md. created this image of Hurricane Sandy using TRMM data.

TRMM is a joint mission between NASA and JAXA, the Japan Space Exploration Agency. Some of the questions about hurricanes left unanswered by the TRMM satellite will be explored by the Global Precipitation Measuring (GPM) satellite scheduled for launch in 2014.

On Oct. 28 Hurricane Sandy was a marginal category 1 hurricane and its eyewall was modest as TRMM revealed. This gave forecasters and scientists hints about its possible strength.

The eyewall looked compact with 40 km diameter and relatively lighter precipitation, and none of Sandy's eyewall storm cells managed to burst and reach, the tropopause which has about a 10 km height at mid-latitudes.

The weak updrafts in the eyewall was due to the fact that the TRMM radar's reflectivity stayed under 40 dBZ, a commonly cited signal strength at which updrafts can be vigorous enough to form hail and to lift smaller ice particles up through the tropopause and into the stratosphere.

Most hurricanes only have well-formed and compact eyewalls at category 3 strength or higher. Sandy was a category 1 hurricane also experiencing strong wind shear, Sandy was going over ocean typically too cold to form hurricanes.

Kelley said, "With infrared satellite observations used in imagery one can speculate about what the sort of convective (rising air that form the thunderstorms that make up a tropical cyclone) storms are developing under the hurricane's cloud tops, but Sandy was sneaking up the East Coast too far out at sea for land-based radars to provide definitive observations of the rain regions inside of the hurricane's clouds." The radar on the TRMM satellite could provide this missing information during this overflight of Hurricane Sandy.

A super-sized rainband was also shown by TRMM satellite that was extended from west and north of the center and had storm cells. This rainband was what lashed the coast well before the hurricane's center make landfall. 

And why some states are experiencing snow storms? When a warm and moist air mass collides with much colder air the resultant precipitation turns to snow.