Southern California MudslidesIn the middle of California’s most catastrophic drought on record, a freak tropical rain storm caused deadly floods and destructive mudslides in the Southern California San Gabriel Mountains this past Sunday. The National Weather Service is calling it the kind of weather event seen only once about every 500 years.

Starting mid-afternoon, the storm dropped nearly 4 inches of rain onto Mt. Baldy in a single hour, triggering mudslides and floods that killed one motorist and severely damaged more than 30 homes.

The deluge also cut off the small town of Forest Falls after a ten-foot mudslide buried the town’s sole road connecting it to the outside world. San Bernardino County firefighters are still assessing the damage but noted that about 100 buildings had sustained damage. Two other communities, Mt. Baldy and Highland also had home damage.

The death toll was one person and two dogs. Forecasters said that at times the rain was likely so thick, drivers would have been unable to see far in front of them.

Now put this new word in your vocabulary today – Orographic. The storm was caused by orographic flow. This is when moisture-saturated air is pushed up by a mountain’s natural topography and is squeezed like a sponge. A wave of tropical air blown north from Central America gave the storm and extra punch of moisture.