It is actually lightning seen from a distant thunderstorm too far away for the thunder to be heard. Follow weather reports. Make sure a battery-powered radio is nearby. Do not turn on the television. Listen to Noaa Weather Radio for the most current information.
Lightning can cause power surges.
Unplug all appliances before the storm hits. Avoid using the phone. Telephone lines can conduct electricity. Metal pipes also conduct electricity. Stay away from faucets, sinks, and bathtubs.