I'm not exactly sure which setting it is, but it's mostly cloudy, and the clouds will appear instantly. They don't roll in or anything like that it'll be clear sky then bam low lying clouds instantly. 

I have the timed events set to run a random event every 61 minutes

Also is there a way to make it favor storms? 

{
  "EnableInGameTime-Timer": false,
  "EnableRealTime-Timer": false,
  "EnableTimerOnce": true,
  "EnableTimerRepeat": true,
  "InGameTime-Timer": {
  },
  "RealTime-Timer": {
  },
  "TimerOnce": {
    "weather.clear_chance 1": 5,
    "weather.dust_chance 0": 6,
    "weather.fog_chance 0": 7,
    "weather.overcast_chance 0": 8,
    "weather.rain_chance 0": 9,
    "weather.storm_chance 0": 10
  },
  "TimerRepeat": {
    "rw random": 3700
  }
}​