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Lightning storms, fire storms, and fire tornadoes

The movie "Into the Storm" was recently released as block buster from Hollywood. While 'some' of the movie tornadoes were fairly authentic, the computer generated cloud structure in the movie, supporting tornadic storms, were 'ah not so authentic.' One of the scenes in the movie that was 'hotly' debated was a scene where a fire was started in a town, with presumably downed power lines that became the catalyst for ignition, and with sufficient gasoline engulfed into a twister vortex, the result produced a fire tornado. Having seen fire whirls over the past decade, along with a number of pervasive mesocyclone-type fire tornadoes, there are now fairly well understood circumstances that tend to produce fire funnels, usually in forested or dry brush areas with very low surface dew points when wild fires and flash burns can be maintained by strong surface winds.

Amazingly powerful firenado at close range rips trees out of the ground and lofts them hundres of meters into the air.
Amazingly powerful firenado at close range rips trees out of the ground and lofts them hundres of meters into the air.
Chris Tangey (Copyright 2012) firenado
Afternoon convective storm produces lightning
Chris Hill

Looking back to 2012 in Australia, where film maker Chris Tangey captured the now historic 'jet engine sounding' persistent natural fire tornado, conditions producing the vortex are fairly obvious. We can see commonalities with other deadly fire tornadoes, mainly through assessment of tornado damage. Chris's exemplary footage documented trees being ripped out of the ground, lofted hundreds of feet into the air and ejected outside the path of the advancing fire tornado (Chris also has an archive of such damage pictures close up). Chris's footage also shows the fire tornado rotated in a clockwise direction, whereas north of the equator, such a firenado would rotate counter clockwise.

The destructive and deadly Canberra, Australia fire tornado of January 2003, showed, through engineering damage assessment from within affected areas in the city, that such fire tornadoes can pack EF tornado strength winds equivalent to their vapory high moisture counterparts. Last year, near Tetlin Junction, Alaska, a massive arctic wedge fire tornado vaporized large forest areas in seconds on August 16th, 2013. Not only do fire tornadoes often exhibit a rope structure, as was documented in Australia, but such fire tornadoes with enough fuel, surface winds, and upper air support, can support fast moving super heated wedge-like fire tornadoes.

Fire tornadoes burn extremely hot, in the thousands of degrees, due to volumes of high velocity burning air being consumed in the rotation. The heat within a fire tornado core is incredibly buoyant rising quickly compared to surrounding ambient air temperatures outside the fire vortex. As Chris Tangey's Australian video so amazingly captured, the fire tornado actually sounds something like a jet engine or huge water fall. This type of sound is usually only present in the strongest EF-strength water vapor tornadoes. Why, beyond the obvious, are firenadoes a concern for fire fighters, is that fire tornadoes can change directions and speed, and take unpredictable paths that defy conventional logic of forest fighting strategies. What often triggers events that culminate in fire tornadoes are dry lightning strikes from weak convective storms that have enough support to develop cumulus clouds capable of producing lightning, but not sufficient enough water vapor to produce abundant condensation and heavy rains over the same area.

Colorado is currently experiencing daily monsoon afternoon thunder storms, and so far these storms have come with significant rain typical of late July-early August storm patterns.

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