PlanetsCentral

Voltage_change =
   4 + 2 * Random(6)
   ...i.e. 4 to 14 in steps of two
Radius_change =
   Random(11)
   ...i.e. 0 to 10
New_voltage =
   Old_voltage - Voltage_change
   ...Storm disappears if this is zero or less
New_radius =
   Old_radius + Radius_change

Pancaking Effect: The pancaking effect has a probability of 1:33 to occur, and happens after normal radius and voltage changes. This may change the storm into a growing one.

Voltage_after_pancaking =
   Round(Sqrt(New_voltage))
Radius_after_pancaking =
   2 * New_radius