Thanks to satellite imagery done in part by researchers at the University of Wisconsin-Madison through the Cooperative Institute for Meteorological Satellite Studies, people along the mid-Atlantic coast were prepared for the worst when Superstorm Sandy made landfall Oct. 29.
“I think this storm was very much a success story,” CIMSS research specialist Derrick Herndon said. “If this storm had hit 30 [to] 40 years ago or longer, that 13-foot storm surge that came into Long Island … wouldn’t have been prepared for. They wouldn’t have known it was coming.”
Herndon is right at the center of UW-Madison’s effort to provide satellite imagery to agencies such as the National Hurricane Center so they can properly forecast both the path and intensity of storms. Herndon and other researchers at CIMSS look at the satellite imagery of storms in the tropics and attempt to use that data to analyze the features of the storm and predict its wind speeds, structure and size along with other systems that may affect it.
“From the satellite data, we can extract all this information … and that was so key for Sandy,” Herndon added.
The first indication Sandy was developing into a hurricane came on Oct. 19, according to Herndon. Prior to this point, Sandy was being tracked, but the then-tropical wave had not shown much life as it sat in the Caribbean. However, the storm became more organized, developing areas of severe thunderstorms.
Herndon explains this organization was just the thing that researchers look for.
“When we start to see this kind of organization in the satellite imagery, that’s an indication the storm is becoming better organized,” Herndon said. “That’s when we started really taking notice of Sandy.”
However, there was still a lot of uncertainty at this point as to where the storm was headed and if it would make landfall in the United States. That is where the computer models, which relied on the data Herndon and others analyzed, came in.
The data collected from the satellite imagery are fed into numerous models used to forecast storms, and each of these models use different physics and have their own way of using the data from the satellites. In the early stages of hurricane forecasting, these models often do not agree completely so forecasters generally take a consensus of the various models, according to Herndon.
“The tighter the consensus is, the more confidence we have,” Herndon said.
Sandy posed a sort of dilemma for the analysts and forecasters. As the hurricane moved over Jamaica and Cuba out into the Atlantic Ocean, some models were saying the storm would continue into the ocean towards Spain while others were saying it would curve back towards the East Coast. Ultimately, Sandy did turn back towards the United States, and Herndon was able to point to the exact cause of the storm’s path.
“The system that caused Sandy to turn back towards the Northeast United States was a disturbance in the upper atmosphere off the coast of Alaska,” Herndon said.
About five days prior to Sandy making landfall, a low pressure system in the Gulf of Alaska began to make its way down into the continental United States, where it intensified in the upper atmosphere and pulled Sandy back towards the coast.
If it was not for satellite imagery, the existence of this disturbance would not have been taken into account or even known. However, the low pressure system was discovered and the models were able to predict its effect on Sandy.
“You’ve heard of the chaos theory … that’s not far from the truth,” Herndon said. “These very small-scale features in the atmosphere can … have a tremendous impact on the … outcome of the models.”
“The models nailed it about five days out,” he added.
Because of the work Herndon and others did in analyzing satellite imagery and data to accurately predict the path and intensity of Superstorm Sandy, warnings were properly issued and people were able to prepare for the worst case scenario and evacuate.
Herndon added, “I personally take some solace in knowing that if we could help to improve the forecast, then what we can do is get as many people away from harm’s way as possible.”
