Thunderstorms & Chronomagic

Since The Timekeeper perished at exactly midnight during a thunderstorm, there is a chance that during a thunderstorm, something magical relating to time will happen. 
This is the case with Lukas where the electricity was cut during a heavy thunderstorm and brought four ghosts forward in time to Lukas' house. Diana also had something happen to her during a thunderstorm, but it had more devastating consequences. She "died" during a thunderstorm and in order to save her life, she was connected to a pocket watch in the living room. This did cause her to enter an alternate dimension where all of Dascery disappeared due to unknown circumstances. 
Spoiler: all the Dascerians had perished due to the secret of an atomic bomb getting leaked and exposed to the public.

Manifestation

Two elements have to be in the same vicinity/proximity in order to have this chance work:

• A raging thunderstorm (may or may not cut the electricity
• A watch, pocket watch, grandfather clock, or any older device that can tell the time (not electronic like a digital alarm clock or a phone) to be fully functional and to tell the right time