Marines are able to be deployed at the behest of the President at any time an Executive chooses as long as the deployment doesn't interfere with the core objectives of the Marines. (As in, they cannot be deployed to put down revolts or become garrison since Marines must maintain amphibious operational perspective)

Flooded cities and states, technically, ensure Marine deployment at the prerogative of the President without violating that power.

And technically, so do snow storms since snow is water.

Good luck, Denver.