Sunday, 28 October 2012


NASA's Hurricane Web Page

NASA Satellites See Sandy Become a Hurricane Again and Strong Winds Expand
- Sandy weakened to a Tropical Storm and strengthened back into a hurricane early on Saturday Oct. 26, and its pressure was dropping, meaning that the storm is intensifying as it becomes an extra-tropical storm. NASA's TRMM satellite identified heavy rain falling within the system
and NOAA's GOES satellites provided a picture of Sandy's massive size.

NASA's TRMM satellite identified a huge span of moderate rainfall with heaviest rains happening north and east of Sandy's center. NOAA's GOES satellite imagery clearly shows the extent of Sandy's massive cloud cover and the long line of clouds associated with the cold front that stretches from Maine to the Gulf coast.

Sandy continues to merge with a cold front and is creating a monster storm with a massive reach. The combination is expected to bring heavy rainfall and tropical-storm-force sustained winds for a couple of days to the Mid-Atlantic and northeastern U.S. beginning late Sunday. Sandy is truly the "bride of Frankenstorm" because the storm's circulation is over 2,000 miles and the wind field of tropical-storm-force winds is hundreds of miles in diameter. The Weather Channel cited a concern for power outages from Maine to Virginia as a result of this storm.

NOAA's GOES satellite clearly shows the extent of the monster merging of systems. A hybrid image of NOAA's GOES-13 and GOES-15 satellite created on Oct. 27 by the University of Wisconsin's Space Science and Engineering Center, Madison, provided a full view of the cloud cover from Hurricane Sandy interacting with the long line of clouds associated with the cold front approaching the eastern U.S. The composite image was created using SSEC's McIDAS software and NOAA's GOES imager satellite imagery.

Sandy's Effects from the Nation's Capital to the Big Apple

Washington, D.C. is in the southern end of the bullseye area of Sandy's huge center, and that target area stretches all the way to New York City. That's just the bullseye area, according to the National Hurricane Center. Because Sandy is thousands of miles wide, the storm's powerful effects will be felt all the way to Maine and include strong winds and flooding rainfall. Coastal flooding a very serious concern along the coasts especially in the vicinity of New York City and Raritan Bay, according to the Weather Channel.

Washington, D.C. and New York and all areas in between, including Philadelphia, can expect heavy rain and damaging winds over a couple of days. Because Sandy is coming from the south, the conditions will deteriorate from south to north, with Washington, D.C. feeling the worst effects first.

In the Nation's Capital, a flood watch was already posted along the D.C. and Baltimore corridor west to Frederick County, Md. and south to southern Maryland beginning Sunday night, Oct. 27 and extended through Tuesday, Oct. 30. Rainfall will depend on the speed and track of the storm, but heavy rainfall can flood rivers and streams through the rest of the week. Like the heavy rainfall, damaging winds of tropical-storm-force are expected over the same period. Tropical-storm-force winds range between 37 mph and 73 mph. In addition, coastal flooding is a serious concern because of the easterly winds pushing the ocean waters against the shoreline, and this is coupled with higher than normal tides by the current full moon.

NASA's TRMM Satellite Gets a 3-D Look at Sandy's Power

The Tropical Rainfall Measuring Mission (TRMM) satellite flew above hurricane Sandy on Friday, Oct. 26 at 1509 UTC (11:09 a.m. EDT) and gathered data on rainfall and cloud heights, revealing the power within this monster storm.

Hal Pierce of NASA's TRMM Team at NASA's Goddard Space Flight Center in Greenbelt, Md. created rainfall and 3-D imagery of the storm that revealed the rate at which rain was falling throughout the mammoth storm, and the heights of the thunderstorms within, which are a clue to the storm's power. The higher the thunderstorms that make up a tropical cyclone, the stronger the overall storm, and the heavier the rainfall in those areas of highest cloud tops.

TRMM data showed that rainfall was very heavy in some bands north of Sandy's center of circulation and that Sandy's surface center of circulation is exposed south of the main area of convection. The TRMM rainfall analysis was created using data from two instruments on TRMM: TRMM's Microwave Imager (TMI) and Precipitation Radar (PR).

Pierce created a 3-D view of Sandy, also using TRMM Precipitation Radar (PR) data that showed that the thunderstorms north of Sandy's center of circulation reached heights of a little above 11km (~6.8 mile). Radar reflectivity values of a little over 45.8dBZ were found in these storms indicating that there were moderate to heavy rain showers in that area.

The National Hurricane Center (NHC) indicated that there was significant movement of cold air over the southwest side of Sandy's circulation on Friday, as a result of the cold front moving in from the west. This is expected to speed up Sandy's change to a post-tropical low.

Where is Sandy on Saturday, Oct. 27?

A Tropical Storm Warning is in effect for the Florida East Coast from Sebastian Inlet to Saint Augustine, South Santee River to Duck including Pamlico and Albemarle Sounds, and Great Abaco and Grand Bahama Islands. A Tropical Storm Watch is in effect for the Savannah River to South Santee Rive, the Florida east coast from north of Saint Augustine to Fernandina Beach and Bermuda.

On Sat. Oct. 27, at 8 a.m. EDT, Hurricane Sandy's maximum sustained winds were near 75 mph (120 kph). Sandy is a category one hurricane on the Saffir-Simpson Hurricane wind scale, and regained hurricane strength after weakening to a tropical storm earlier in the day. Sandy was centered near latitude 28.8 north and 76.8 west. Sandy is moving north-northeast near 10 mph (17 kph) and is expected to turn northeast then north on Oct. 28, while slowing down. The center of Sandy will continue moving away from the northwestern Bahamas this morning and will move parallel to the
southeast coast of the United States through the weekend, according to the National Hurricane Center.

Storm surge is expected to be big factor as Sandy approaches the Mid-Atlantic coast. Very rough surf and high and dangerous waves are expected to be coupled with the full moon. The National Hurricane Center noted that the combination of a dangerous storm surge and the tide will cause normally dry areas near the coast to be flooded by rising waters. The water could reach the following depths above ground if the peak surge occurs at the time of high tide.

Powerful Winds Have Already Expanded

As happens when any storm becomes extra-tropical, Sandy will go from a warm to cold core center and the strongest winds spread out and the storm will expand. According to the National Hurricane Center, hurricane force winds have expanded on Saturday, Oct. 27 and now extend outward up to 100 miles from the center. On Oct. 26, those hurricane-force winds were only 35 miles out from the center. Tropical-storm-force winds have also expanded over a huge area on Sat. Oct. 27 and now extend 450 miles from the center! Just a day before, those tropical storm force winds extended outward up to 275 miles (445 km). The wind field of Sandy will continue to grow in size during the next couple of days. The storm's circulation now reaches more than 2,000 miles.

NASA satellites will continue to provide forecasters at the National Hurricane Center with infrared, visible, cloud height, temperature and rainfall data as Sandy closes in on the U.S. East Coast. Updates on Sandy are available from the National Hurricane Center at:

Rob Gutro
NASA's Goddard Space Flight Center

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