Earlier this week, SPoRT obtained cloud-free ASTER imagery over the Moore, OK area. The new imagery clearly shows the tornado damage path across the area. ASTER imagery also shows where the tornado path changes width and direction as it tracked across the city. The ASTER damage track lines up with the storm survey performed by the NWS forecast office in Norman, Oklahoma. In this false color image the track is of the tornado is quite visible. The track in ASTER imagery begins on the west side of the Canadian River. It then tracks across the river and into the city of Moore.
This second image is the Normalized Difference Vegetation Index, which emphasizes differences between vegetation and the urban area. The brighter areas of the image show where the vegetation is living and healthy, while the darker areas are a mix of water, urban areas and roads. The tornado track is quite visible in rural areas due to the vegetation being disturbed. The urban areas appear dark as well, with debris producing low NDVI values and a loss of detailed texture in road networks and neighborhoods evident in the non-damaged areas.
The ASTER damage track can also be compared to the official damage survey and available radar data. Below is the 1955z radar image and storm survey overlaid on the NDVI imagery. The tornado had been on ground for about 3 miles to this point and had only produced EF-0 intensity damage. The radar hook echo lines up with the track very nicely but NDVI has little to no change.
As the tornado intensified, it is increasingly evident as a “debris ball” defined with higher radar reflectivity. The damage survey confirmed an EF-2 intensity as well as a small pocket of EF4 damage. The NDVI scar is much darker along the survey track where vegetation was damaged and adjacent areas were disrupted.
Additional imagery can be found here on the SPoRT’s website.