April 2020 Upstate GA-SC Tornadoes

These change in NDVI maps were produced using pre-storm baseline April 11, 2020 and a post storm date of April 16, 2020.  Based on the status of MODIS NDVI for the week ending April 13, 2020, the forests of this area were on average 42% greened-up at the time of the storm. This means that there were plenty of deciduous leaves and potential leaf stripping in hardwood - dominated forests. That phenomenon may account for some of the departure and make it difficult to resolve actual structural damage from ephemeral impacts.

In addition, there are minor areas of departure in built-up areas (towns, roads) that may or may not reflect actual damage to vegetation. Places with fine-scale patchiness can contribute to differences in tree and building shadows between the pre and post event imagery, and even after atmospheric correction can create a false vegetation change signal. Surface wetness may do the same.