As the unit addresses their damages and tries to reduce as much as they can, the flow of water down the river suddenly drops to almost nothing and Max forms his thermal scanners towards the black cloud.
It is a Thermal shock wave from an intact mother ship collision with solid ground. It is too thin to show on satellite imagery, but that cloud is thousands of degrees and is flash boiling the flood waters. No wonder it isn't raining behind the wall, it will be a sauna.
[All troops, you have 30 seconds to get in a sealed shelter. That incoming shock wave is going to scorch anything left out in the open.]