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David Spiegler - Weather Expert

Certified Consulting Meteorologist and Fellow of the American Meteorological Society (AMS)

It is well known among lawyers that a reliable witness is almost always better than several pieces of circumstantial evidence. How about an invisible reliable witness? It may sound strange at first, but when you think about an event that takes place out-of-doors, the weather ("Mother Nature") can often be a so called "invisible witness". Law cases in which the weather may be a factor range from slip and fall accidents to motor vehicle, boating, and aircraft accidents, to wrongful death and homicide cases, as well as cases for which damage to -- or loss of -- property from high winds, heavy rain, snow/ice, flooding, and ocean waves occurs.

The analysis and assessment of the weather conditions at the location and time of day, and time of year of the event by a professional meteorologist is known as Forensic Meteorology. It is one of the major aspects of meteorology in which I'm involved. I effectively reconstruct the weather at the time and place of the event, as well as the weather that preceded the event because prior conditions often affect the analysis and conclusions. The forensic meteorology services include not only weather data analysis and interpretation and weather event reconstruction, but also site evaluations at the site of the incident, written reports, expert testimony, and cross examination advice.

One might think that using weather data from the nearest official National Weather Service (NWS) weather station is all that is needed. However, using only those data would be a major mistake and lead to challenges by the attorney on the opposite side. Often, there are large differences in weather over short distances and short periods of time. The great majority of NWS weather stations are located at airports which are not usually located in or near residential or city areas. The airport weather observations may not be representative of the site of the event involved in the litigation.

There are many other sources of weather data available and known to meteorologists. Knowing what they are and how to access the sources allows me to conduct an analysis and assessment of the weather over an area and/or a specific location, and reach conclusions with a high degree of accuracy and confidence. The analysis and assessment are supported by the data and the interpretation of the conditions at the time and location of the incident/event.

Among the other sources of weather data used by forensic meteorologists to reconstruct the weather conditions are weather radar data that helps to define the location of areas of precipitation including the intensity, movement, and type of precipitation; cloud imagery both in the visible and infrared from weather satellites; a lightning detection system and network that indicates lightning strikes, frequency, and intensity with a fine time and space resolution; and observations taken by a network of thousands of NWS trained cooperative observers across the U.S. who take standard weather observations, as well as noting the onset times and type of precipitation, and the occurrence of rapid changes and/or unusual weather such as hail, high winds, heavy fog, and thunderstorms.

I have worked on all the types of cases for more than 60 law firms in several states. Some of the cases I have worked on include a detailed analysis of the impact of Hurricane Katrina on a hospital in Metarie, LA; and an analysis regarding the impacts of Hurricanes Frances and Jeanne on property in Palm Beach Gardens, FL. In 2008, I prepared a report for a law firm on the impacts of Hurricanes Katrina, Rita, and Wilma on property in south Florida.

I also provided expert testimony about the impact of wind and heavy rain from severe thunderstorms on an apartment building in North Miami Beach, FL, the roof of which had previously been damaged by Hurricane Wilma. Extensive use of weather radar was necessary to accurately define the location, movement, and intensity of the thunderstorms that occurred. And most recently, I developed a report of how a prolonged period of hurricane conditions was responsible for extensive damage to machinery in a factory. Hurricane damage is important to determine for several other cases I worked on.

In northern locations, many cases involve slip and fall accidents. For these cases, it is important to determine the weather conditions that preceded the accident and to do a detailed site evaluation. For example, suppose that a slip and fall accident occurred on outdoor steps when the weather data showed the air temperature to be 35° F with light rain falling. The plaintiff claimed that the steps were icy, but with the temperature above the freezing/melting point of 32o F, was ice really a possibility? It turns out it was - because the records also showed that the temperatures were well down in the 20's and in the teens for more than 24 hours prior to the accident. In addition, the site evaluation indicated that the steps faced to the north which meant no warmth from the sun shining on the steps was possible. Consequently, the surface temperature of the pavement was very likely below freezing and ice on the steps was highly likely.

For most cases, I prepare a report for the law firm with what I did, the factors involved, and an assessment and conclusions I reached with supporting documentation and tables. They use the report to try to win the case, or it helps them reach the type of settlement they are aiming for. When a settlement is not reached, I go to court to testify as an expert witness. In the court testimony, I bring in the "invisible witness" - Mother Nature, and relate what the invisible witness "saw" regarding the impact of the weather on the incident.

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Mr. Spiegler has published over 75 technical papers and reports. Papers in professional journals including: Journal of Applied Meteorology, Monthly Weather Review, Bulletin of the AMS and Weatherwise, as well as numerous presentations at technical conferences and symposia. He has also been a peer reviewer for professional journals. And he was an invited speaker for AMS 75th Anniversary meeting on "A History of Private Sector Meteorology" (Jan. 1995) and authored a chapter on the same subject for a book on a history of meteorology in the 20th century in the United States published in 1996 by the AMS. He recently (2006) performed a survey for the AMS on the current state of the private sector in meteorology. (Published in the Bulletin of the American Meteorological Society, Vol. 88, No. 8 August 2007) Mr. Spiegler is a Fellow of the AMS.

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