Forensic Meteorology – Part 2

crimesceneReconstructing the weather at the scene of a crime or accident may seem easy enough, and it is much easier than it was 20 years ago, but the really good forensic meteorologist knows that at some point there is going to be a lawyer questioning every piece of information – and possibly a jury.

The bottom line is to get to the facts and know exactly what the weather was doing at the time — or at least to be able to narrow the possibilities.

The first thing a forensic meteorologist has to do is read through the existing case reports as it relates to the weather. These are usually police reports which hopefully include photos. Some of the photos may be quite gruesome, most are not.

A word of caution should you want to be a forensic meteorologist: You cannot talk to an outsider about the evidence you see, so if you think you will want to tell someone about the picture of the corpse you can’t get out of your head because it is upsetting, then consider another line of work. Outsiders include spouses and close personal friends.

Photos are a great help in establishing what the weather was like, but they are almost always taken after the fact. It is possible that you may get a photo of an aircraft as it is crashing or a thunderstorm as it is bearing down on a building. Most of the time, however, photos of the scene will be taken 30 minutes or longer after the crime or accident.

Next, all of the available data must be gathered. There are surface and upper air weather observations, radar images, satellite images and any other source of data. Use the police reports as a foundation, but do not trust them since those observations are made after the fact. In essence, you are starting from scratch, making the assumption that you have no idea what the weather was like. Once you piece the weather conditions back together using every piece of weather data you can find, go back and compare it to the reports you have from the case file.

What matches? What does not? You must go back over the data for every bit of information that does not match. Remember, it is possible that the report from the scene may be wrong. After all, those reports are usually made by law enforcement or an insurance adjuster, not a meteorologist.

An experienced forensic meteorologist has a wealth of weather sources to look at. Some are well known data sources, some are obscure and worth revealing only in court documents and not to anyone else. It is often necessary to visit the scene in person to note anything that may influence temperature, wind and other weather elements.

The conclusions drawn by a forensic meteorologist must be based on facts or reasonable scientific assumption, and it must be defensible. However, it is possible that there is a reasonable doubt as to the weather conditions at the time of the event — and you must report that information to the person who hired you.

Next time: On the stand.

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