GIS Use Cases and Conflict of Interest Queries in Forensic Meteorology

AMS Certified Consultant Meteorologists (CCM) are retained by those in the legal field who represent a plaintiff or defendant when a case involves injury or property damage due to adverse weather conditions. These cases are geographically specific, and the investigations often necessitate the interpolation of data from nearby atmospheric observational sites. Using ESRI’s suite of software, Atlantic States Weather, Inc. (ASW) has developed two GIS processes to calculate wind speeds, and a process to compare the timing of high water to winds after a tropical system has impacted a property. The first process results in the development of isotachs based on the height of observations, distance to observations, and exposure of a property under study. Using exposure categories as defined in Section 26.7.3 of ASCE 7-22, and the log-wind calculations as depicted in Dregger 2005, a field of normalized and vertically interpolated winds is developed for a location then contoured resulting in maps to share with clients. The second wind interpolation methodology involves the use of NCEP’s Real-Time Mesoscale Analysis (RTMA) winds used to create a wind raster (or horizontally continuous dataset). The resultant continuous field of winds allows for the corroboration of log-wind point calculations and additional visual aids when communicating weather information to clients. Typically, there are different insurance coverages for wind and water damage. ASW has also employed the use of ESRI software to create a process to determine the timing of maximum storm surge at a USGS gauge. The process utilizes USGS stormtide datasets that are filtered for maximum water depth using a combination of Python scripts and ArcGIS Pro tools. This maximum depth is then interpolated to the damage site using elevation data (NAVD88) to determine the height of water at a property.

The ability to create visually appealing maps of observations and data for a case improves communication between the CCM and client. Additionally, continuing to build upon existing GIS datasets allows for quick internal scans for conflict of interests. Developed using ArcGIS Online’s ‘Instant Apps’ and ‘Survey123’, ASW has a GIS database of cases that can be queried by date, location, and weather hazard type. Continually adding to this database ensures not only conflict avoidance but also continuity of conclusions between cases. Other GIS communication avenues currently under investigation at ASW are the use of ArcGIS Story Maps for specific cases for clients and across the legal field for education on when to utilize a CCM.

Davenport, A.G., “A Rationale for the Determination of Design Wind Velocities,” Proceedings ASCE Structural Division, 86: 39-66, 1960.

Dregger, P., “The Wind Investigator: How to Approximate Wind Velocities at Roof Level”, Interface Journal, 41-44, 2005.

Durst, C. S., “Wind Speed Over Short Periods of Time,” Meteorological Magazine, 89, 181-187, 1960.

SEI/ASCE 7-22, “Minimum Design Loads and Associated Criteria for Buildings and Other Structures,” ASCE/SEI, 274, 2022.