How to make storm effect?

[The chaser]

It's very simple: Just a few lines of code:

Make a BoxLight with 0 light (0, 0, 0, 1).

void OnStart()
{
AddTimer("", RandFloat(0.5, 20), "Thunderstrike");
}

void Thunderstrike (sting &in asTimer)
{
FadeLightTo("BoxLight_thunder", 1, 1, 1, 1, -1, 0.1);
AddTimer("", RandFloat(0.5, 20), "Thunder_effects");
}

void Thunder_effects (string &in asTimer)
{
AddTimer("", RandFloat(0.5, 20), "Thunderstrike");
FadeLightTo("BoxLight_thunder", 0, 0, 1, 1, -1, 0.1);
PlayGuiSound("general_thunder.snt", 1);
}