Here is the National Hurricane Center's forecast for Lee's future movement. S = tropical storm and D = tropical depression.
Between 25,000 and 30,000 are without power at the present time.
Here is the 24-hour (note: not storm total) rainfall ending 7am Central time this morning. There are several areas that received more than 10 inches.
Here is the predicted rainfall from now until 8am Eastern Friday morning.
So, what do you do to prepare if you are in an area where heavy rain is predicted?
Most cities' web sites have flood plain maps for at least the 100-year flood plain. For example, a flood map for Philadelphia is here. If you live in or near a flood plain, please fill your car's tank with gas, and think about what you would need if you have to evacuate.