Firenadoes Sweep San Diego

In the spring of 2014 San Diego was hit by dozens of wildfires that rages throughout the hills. Over 14,000 acres of the San Diego countryside were burned, forcing thousands to evacuate and leaving many homes destroyed. One thing to come out of these deadly wildfires was a fire tornado or "firenado".

These "firenadoes" are immense spires of whirling flames that resemble tornadoes. Despite the name, these strange weather phenomenons aren't tornadoes at all. They are created by the hot, dry air rising quickly from the ground as opposed to the conditions that cause tornadoes; moist air close to the ground, atmospheric instability, and clashing air fronts. When this hot air rises from the ground, it creates vertical "chimneys" and as more hot air is pulled in, it begins to swirl in a vortex. The vortex is created by the angular momentum of the air.This vortex then picks up burning embers, flammable debris, and ash turning it into a dangerous tower of flame.

Most fire tornadoes only last a few minutes. When the hot air rises and cools, the strength of the vortex decreases and the fuel burns out. Despite this, fire tornadoes can get to 2,000 degrees Fahrenheit and extend hundreds of feet into the air.

https://www.livescience.com/45676-what-is-a-firenado.html