How's the weather?

Consider the following: A robbery suspect says he was at a scene 6 hours before a robbery was determined to have occurred. He admits he left his drink behind at the scene but says he left the location hours before. If the suspect is telling the truth, should the ice in the drink have melted from the time the suspect left to the time law enforcement arrived? In another case, a husband accused of killing his wife says he was outside, lounging by the pool when she fell down the stairs. Were the weather conditions at the time of the murder conducive to sitting poolside?

In each of those examples a forensic meteorologist was called in to provide a key piece of evidence.

Yet, at least by name, forensic meteorology hasn’t been around for long. In the last decade, the American Meteorological Society (AMS) has included forensic meteorology among its areas of specialization. Out of more than 9,750 professional AMS members, 108 list forensic meteorology as their main expertise.

Elizabeth Austin, who holds a Ph.D. in physics from the University of Nevada-Reno, is one of them and serves on the AMS Board of Certified Consulting Meteorologists. When Austin was an undergraduate studying atmospheric science in the 1980s, she says forensic meteorology wasn’t talked about. She first heard of forensic meteorology when she was getting her master’s in atmospheric physics. Now, she says forensic meteorology is more of a hot topic. Austin helps teach a combined undergraduate- and graduate-level forensic meteorology course every other year at the University of Nevada-Reno. In addition to meteorology, the course includes case studies, case work, reports (including a federal Rule 26 report), depositions, and a mock trial held in the courtroom of the National Judicial College, located on campus. For the annual AMS meeting in January, Austin and others are putting together a day-long workshop on forensic meteorology.

Like law enforcement, forensic meteorologists find that cases vary greatly. Sometimes they are relatively basic. Austin, president of WeatherExtreme Ltd., an atmospheric research and consulting company since 1994, gives the example of a case she worked in Reno. A man accused of attempting to bomb an IRS building said it was raining when he bought fertilizer, which allegedly was used to make a bomb. Austin was asked to determine if it had been raining.

Cases can also be more complicated. Frequently, Austin is called to help at the scene of an airplane crash, which requires looking not only at weather conditions on the ground, but in the sky as well. In some of these cases, she has needed to collect data from foreign countries, which haven’t always been willing to share their data, or when they have, it’s been more costly than in the United States.

Weather can also play a part in environmental crimes. Stephen Harned, a certified consulting meteorologist and president of Atlantic States Weather Inc. in Cary, N.C., has been a meteorologist for 40 years and has had a consulting firm specializing in forensic meteorology for the past seven. Harned recently was asked to testify about how much rain fell in an area where illegal dumping of hog waste was thought to have occurred.

Often Harned is asked to determine wind speed and whether or not wind speeds were high enough to cause the damage being claimed by homeowners.

Harned says he has not come across a case in which there are no answers.

“There’s enough data and understanding among forensic meteorologists to be able to reconstruct what happened at a specific location and time,” he explains.

To do so, forensic meteorologists use radar, satellite, models and data from various reputable sources.

Obtaining weather data doesn’t always require a forensic meteorologist.

“Law enforcement can do quite a bit on their own,” Austin says, noting that if the case requires expert court testimony, they will want to hire a forensic meteorologist.

Knowing where to find the data isn’t always easy, but there are lots of data out there.

National weather data

The National Oceanic and Atmospheric Administration’s (NOAA’s) National Weather Service issues weather warnings and forecasts, but doesn’t archive data.

NOAA’s National Climatic Data Center has the world’s largest active archive of weather data. NCDC produces numerous climate publications and responds to data requests from all over the world. If law enforcement needs to know what the weather was like on a specific day and time, NCDC has the answer.

NOAA Meteorologist Scott Stephens often receives calls from law enforcement trying to determine if there was snow on the ground, if there was a thunderstorm, or what the temperatures were. In June, for example, he received a call from an officer looking to confirm that temperatures were above a certain threshold because a child had been left in a vehicle.

To obtain answers to these questions, NOAA looks at surface data from airport weather stations that deliver hour-by-hour observations, and from its larger network of weather stations staffed by volunteers, or cooperative observers who measure basic parameters.

NCDC is the official U.S. archive for climatic records. As such, NCDC can certify copies of all records available from NCDC archives. As an archive facility, the only fact that NCDC can attest to is that exact duplicates of climatic records on file at this center have been provided to those that request such data. The standard Department of Commerce or general certification of authenticity accomplishes this. That’s important because records that are to be submitted as evidence in court in most states require authentication.

There is a charge for certified reports. Via the Web site, the base price is $69 while the cost for a paper copy is $109, says Stephens. If more data is needed, the cost is higher.

Regional weather data

NCDC is part of a three-tier national climate services program, which includes six regional climate centers and state climatologists.

At the Western Regional Climate Center at the Desert Research Institute in Reno, Nev., Jim Ashby often received calls from law enforcement working on crash reports. Ashby was a climatologist for 30 years and retired in June. To answer law enforcement inquiries, he would tap into the regional center’s many data sources. They include daily climate observations from more than 2,600 active stations, summarized monthly climate data from 5,240 stations, hourly precipitation data from more than 1,930 stations, twice-daily upper air soundings from about 50 stations, surface airways hourly observations from more than 1,800 stations nationwide, the Remote Automatic Weather Stations system, historic lightning data through 1996, access to Natural Resources Conservation Service SNOTEL (a network of snowpack data collection sites), 3,000 climate stations on the Web for the Western states, and more than 200,000 Web pages.

Regional centers know where the closest weather observation stations are relative to a crime scene. Austin notes personal weather stations, which are not official, can have reliable data, but not always. For example, they might be set up in a location where the wind is blocked part of the time.

Because crimes or traffic crashes don’t always occur near an official weather station, or there may not be a weather station of any kind around for miles, Ashby advises law enforcement officers note the weather at the time of an incident — especially if it’s windy or there’s a thunderstorm in the area.

“These events can be very local in nature and the nearest station may fail to mention wind or thunder,” he says.

Regional centers do not provide certified documents, which are commonly requested. Though the regional centers don’t certify data, Ashby says records clerks can sign an affidavit stating that the data contained in a document has not been modified.

Astronomical data

Knowing astronomical data, including sun and moon position, can also be helpful. Austin was once asked to determine what the lighting conditions were the night that a couple had been murdered. A witness said he saw the defendant enter the home on the night of the murder. To establish what the lighting would have been like then, Austin measured the terrain, looked at cloud cover, humidity, temperature, and sun and moon positions. She explains there are different twilights (twilight, civil twilight, nautical twilight and astronomical twilight). Each lasts 20 to 35 minutes.

Astronomical data can be obtained from the Navy. The United States Naval Observatory, reporting to the Navy Oceanography and Meteorology Command, determines the positions and motions of the Earth, sun, moon, planets, stars and other celestial objects; provides astronomical data; determines precise time; measures the Earth’s rotation; and maintains the U.S. Master Clock. The U.S. Naval Observatory makes its products available to the public through the Naval Oceanography Portal (see box on Page 47).

Standard data for law enforcement

Even if law enforcement doesn’t look up weather using the various sites available online, Austin suggests law enforcement officers have standard weather data that they gather. Like Ashby, she suggests officers note current weather conditions, as well as surface conditions (wet, icy, dry, etc.), atmospheric conditions (lighting, visibility, winds and so on).

“You never know at the beginning what’s going to be important,” she says. “Even after the occurrence of an event, this information is still very valuable, as are photographs taken on scene.”

Certified consulting meteorologists

When law enforcement has questions about what’s important or how to find the answers to important questions, forensic meteorologists can help.

Harned estimates there are several hundred forensic meteorologists in the country, but notes just over a hundred of them, including himself, are AMS certified consulting meteorologists.

“Meteorology is an unregulated profession,” Harned says. “A lot of people don’t realize that. There are no state licensing boards or exams meteorologists take to call themselves consulting meteorologists.”

AMS recognized a need for a professional certification with qualifications for the CCM program centered in knowledge, experience and character.

“The program is pretty rigorous,” Harned says, adding it’s a good way for people to ensure they have a reputable consulting meteorologist — in any kind of weather.