There is also a new tool (looks crude — hopefully it is effective) that is described as:
"The online geoelectric field tool that was developed by NASA Goddard Space Flight Center and DHS Science and Technology Directorate (S&T) allows computation of the ground geoelectric field for a given single point geomagnetic field time series and one-dimensional (1D) ground conductivity model. The tool uses the simplified plane wave source and 1D ground formulation of the geomagnetic induction process. The horizontal components of the geoelectric field are computed."
OK, so it is not for your average emergency manager, more suited for those working in the electrical power industry, but it appears to let them model what might happen.
Neil Clement shared the links above.