Thursday, March 4, 2010

Man vs. Nature: Interview with a Forensic Meteorologist

As many of you already heard, earlier this week I had the chance to interview AccuWeather Forensic Meteorologist, Steve Wistar. From the basics of forensic meteorology to the intricate weather details that help solve civil and criminal legal cases, we had a highly informative and instructive conversation, and I’m excited to share what I learned.

First I discovered Wistar has been an avid weather buff since the age of five and as a previous member of the Future Meteorologists of America, he has been studying meteorology since the sixth grade. He graduated from Penn State University where one of his professors was AccuWeather founder, Joel Myers. Wistar officially joined the State College, PA-based AccuWeather team in 1976, and proceeded to forecast the weather through major radio and newspaper outlets. In 1995 Wistar joined AccuWeather’s forensic meteorology initiative. Contributing his expertise and acting as an expert witness in some of man vs. nature’s most interesting cases, he’s been a consulting meteorologist in that department ever since.

Wistar explains, “Forensic meteorology is the process of reconstructing past weather conditions at a particular time and place to determine what happened in a given location.” Using all the data at their disposal, i.e. satellite, Doppler radar and real-time weather reports, as well as knowledge of an actual site, forensic meteorologists provide analysis to law enforcement in cases where weather could be a significant factor. Most of the cases AccuWeather works on are civil, such as roof collapses, slip-and-falls, severe wind damage, and car and plane crashes. However, on rare occasions they are called on to testify in criminal cases.

In a typical case of homeowner vs. building constructor, Wistar walked me through the analysis of common roof collapse as a result of heavy snow accumulation. The first determination comes from actual weather reports at the time and place of the event. Forensic meteorologists then reconstruct the weight of the snow, which is generally based on water content, and is determined by looking at the period of time the snow built up, as well as sublimation on the top layer of the snow, if rainfall occurred, and if there was snow drifting that would lead to uneven placement. After this is determined, engineers are called in to provide critical information as to whether or not the roof would have been able to handle the weight. Wistar says, “In many cases where snowfall is at historic levels, such as last month, many roofs just are not able to handle the weight. At times like this the weight simply exceeds the building code.”

In what was likely one of Wistar’s most challenging experiences as a forensic meteorologist, he was called on to visit the Louisiana and Mississippi coasts after Hurricane Katrina in 2005. Over an 18-day period he analyzed more than 250 cases of damage, trying to determine the major source of destruction. In a time where the blame was mostly placed on the 20 + foot storm surge [and breached levees], Wistar and his team were able to tell the difference between homes damaged by the surge and those damaged hours earlier by 100 + mph winds from a tornado or microburst. This information proved invaluable to the homeowner in filing insurance claims unrelated to flood damage.

When asked for specifics, Wistar mentions, “By looking at Doppler radar we were able to tell when intense, rotating thunderstorm cells moved over a particular location, and in some cases, it was well before the storm surge arrived. This really changed the equation, especially for the insurance companies.”

Now if you’re like me, you probably want to hear the details on how forensic meteorology has been used to solve criminal cases. Wistar shared two stories, one of which was documented by CourtTV and the Discovery Channel. The case surrounded a domestic dispute between a dentist and his wife, which led to the wife’s death. The crime was largely solved by the expert knowledge provided by the AccuWeather team.

Panicked about what to do and how to appear innocent, the dentist [the alleged killer] consulted with his brother and devised a plan to make the scene look like a burglary. After ransacking their second floor apartment and setting a ladder up against their window, the dentist called the police and informed them of the ‘murder.’

When the police arrived, something just didn’t add up. It was a damp autumn night and there was dew on everything – the grass, the trees, the cars. However, there was no dew on the ladder, and one of the cars in the driveway didn’t have dew on it either. The scene made no sense. That is where forensic meteorology came in and that is when AccuWeather was called. Passionate about AccuWeather’s input in the case, Wistar acknowledged, “We were able to help them understand the timeline of what happened and why there wasn’t dew present on these objects, and the case was solved! And hey, that was pretty cool!”

Wistar and I spoke about several other cases, both civil and criminal. I must say I learned a great deal from our conversation. As if I didn’t already have an enormous appreciation for weather, I now have a new found admiration for these experts who are able to tie in the complex elements that bind the science of meteorology with forensics.

I am so grateful to you, Steve, for taking the time out of your busy weather predicting/reconstructing, and crime solving day to speak with me. And thank you in advance for the invitation to visit the AccuWeather studio. I will definitely be taking you up on the offer!

I hope that everyone who reads/read this blog post is by now as fascinated as I am. In looking to the future I hope to learn more about other corners of meteorology by speaking with a variety of professionals in the field.

Stay tuned!