On 6/3 a weather system went through the Antelope Mine. At 8:00PM the SMA pit was evacuated due to lightening. A rain storm followed at 11:00PM. When the shift supervisor went back to the pit to inspect for hazards she noticed that the pit was taking on water. She immediately called the Safety Manager at 2:35AM & the MSHA 800 number to report the inundation of rain water at 2:42AM.