The group of supercell thunderstorms that produced the outbreak formed on September 1st, 2017 around 4 pm Pacific time due to extreme instability brought about by the impending shutdown of the thermohaline circulation and the first tornado touched down in San Bernardino county at 4:40 pm. Meanwhile, Los Angeles was battered by winds of 85 mph and hail the size of grapefruits as more tornadoes touched down in San Bernardino and Orange counties. The super tornado touched down in Santa Barbara at 5:03 pm and initially started out at EF-3 strength before rapidly intensifying as it headed straight for downtown Los Angeles, obliterating Ventura and Thousand Oaks while Malibu received 5-pound hail, torrential rains, and winds gusting to over 100 mph along with rough surf and rip currents. At 5:16 pm, the tornado was over two miles wide and a doppler on wheels truck clocked surface level winds at 325 mph. A Tornado Emergency was declared not only for Los Angeles but for all of Southern California.
Los Angeles, which had already seen a series of smaller tornadoes ranging from EF-0 to EF-2, including two that merged at Los Angeles International Airport, resulting in the airport's destruction and several planes being thrown around as if they were toys, was barely prepared for the destruction that the super Tornado would bring. The two-mile wide monster would completely level the city, including the entire Los Angeles skyline and downtown Los Angeles would be reduced to nothing. Even the tallest skyscrapers in the city would be no more and all that remained was stone slabs that composed the foundations of many of the area homes, which had cracked from the winds of the twister. At 5:35 pm, the super tornado left Los Angeles to continue its path of destruction, completely leveling Anaheim before finally dissipating just south of Palm Springs.
Meanwhile in San Diego, another EF-5 tornado had leveled the city with winds clocking in at 295 mph although the damage wasn't quite as severe and less people died than in Greater Los Angeles. However, the damage was very severe. Buildings were ripped from their foundations and even the stone slabs that composed of the foundations were worn down. Despite leveling San Diego and the surrounding area, the tornado dissipated shortly after crossing the US-Mexico border into Baja California.