What The Hell Is That?

I went to bed early tonight but all of sudden I was woken up by the sound of thunder and seeing the lighting outside our window.
And of course, the weather people said there was a 0% chance of rain today. 
Seriously, how hard is it to forecast weather in Las Vegas?  It probably rains 10 times a year and the rest of the time, it is clear to partly cloudy and it is windy some times. 
But I guess the weather forecasters in Las Vegas were wrong again.  What a shock.