Reanalysis of Tornado Damage using ArcGIS, Satellite Imagery, and High Resolution "Gray Sky" Imagery

The National Weather Service (NWS) traditionally relies on ground-based storm surveys to assess tornado tracks and damage, which can be hindered by challenges such as the inability to access land due to heavily wooded areas, private property, and time constraints. These complications can negatively impact the accuracy of the survey. To address these limitations, this project implements an alternate method of mapping tornado damage using ArcGIS, Sentinel-2 satellite imagery, and high-resolution “Gray Sky” aerial imagery. Sentinel-2 data provides information on the vegetation water content, enabling a comparison of pre- and post- tornado conditions to identify areas of damage. Additionally, “Gray Sky” imagery has to be requested after tornado events, but it offers high resolution images of the damage.

The methodology above is applied to create a reanalysis of a complex tornado outbreak that occurred on January 12th, 2023 in Spalding County, GA. The goal is to achieve a more accurate assessment of the tornado track, which is crucial for both affected communities and the research field. The results of this reanalysis reveal multiple areas of damage that are missing within the original record, as well as locations incorrectly identified as impacted, particularly in highly wooded regions. This method, although time intensive, offers a reliable supplement to ground surveys, especially in areas that are hard to survey by land.