Wildfires are nightmarish scenarios that have become a reality for many people not only in California but also across the globe. These catastrophic events not only threaten life and property but also within a blink of an eye can grow out of control. Bringing about new dangers outside of the fire itself.
An example of bizarre behavior within a wildfire was brought to public attention via a home recording from Portugal. The short clip depicts a scene that has seemingly been taken out of the newest Hollywood disaster flick. An out of control wildfire is seen ravaging the countryside coupled with what appears to be a tornado that is on fire. The title of the video was “Portugal Fire tornado”. But what exactly is a “Fire Tornado”? Further research into the subject reveals that the so-called ‘Fire Tornado’, is a misnomer. The video from Portugal captured what is actually known as a fire whirl. A fire whirl is defined as a cyclone, or whirlwind induced by fire and is comprised of flame debris or ash. The fire whirl, commonly dubbed fire tornado, fire devil, or firenado, results when air at the surface is heated, loses density and begins to rise. The rising air leaves an open space for cooler air to rush in. The newer cooler air becomes heated and rises, and the cycle continues and each rising thermal contains a combination of ash, fire, and debris. The vorticity or spin of the rising air will “tighten up” into the recognizable funnel shape, similar to when you drain a bathtub. These fire whirls are unpredictable and extremely dangerous for first responders attempting to extinguish the inferno.
However, fire whirls are not technically considered to be a meteorological event. Conversely, some wildfires can become so expansive and release enough energy that they generate their own wind systems and form what is known as a firestorm. Firestorms are not exclusively produced from wildfires, but can also result from aerial bombings and explosives. Because these firestorms have their own wind systems, they can manufacture weather systems. When the heat and moisture from the fire rise into the atmosphere a pyro-cumulonimbus cloud can form. These marvels behave the same as regular cumulonimbus clouds but the fact that pyro-cumulonimbus clouds do not exist outside of the above conditions is a key distinction between the two.
Pyro-cumulonimbus clouds have been known to yield thunder, lightning, hail, and rain. In January of 2003, a severe bushfire had spread in Canberra, Australia and decimated the area. After the bushfire was contained, locals were left with nothing but the task of cleaning up the devastation. While surveying the area, a puzzling discovery was revealed. Along with typical destruction associated with bushfires, there was extraordinary amount of damage that was not consistent with fire. Cars had been tossed and scattered about like toys and rooftops had sustained severe damage associated with high winds. Later, a local resident released video footage he had taken of what appeared to be a funnel within the out of control bushfire. It was later discovered a pyro-cumulonimbus cloud spawned a fire tornado that reached wind speeds of 111 to 135 miles per hours, measuring an EF-2 on the Enhanced-Fujita scale. Because of the unpredictability and sporadic nature of wildfires, fire tornados are a rare occurrence and are difficult for scientists to study. In fact, fire tornados were only recently discovered.
One can hope that amidst all the devastation and destruction plaguing California, it will allow scientists the opportunity to learn more about these destructive events and provide the public with new techniques regarding fire prevention and safety.
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©2017 Weather Forecaster Ali Van Fleet
DISCUSSION: A large fire is currently burning in Ventura County in California. The Thomas Fire as it is named has currently burnt over 65,000 acres with no containment so far. The spread of the fire has even crossed U.S. Highway 101. The fire is currently burning at a rapid pace because of high winds with gusts around 40 to 50 mph (35 to 43 knots) as well as dew point temperatures as low as -5 degrees Fahrenheit at nearby locations such as Sandberg and Camarillo. These conditions are prevalent as a direct result of the Santa Ana wind phenomena which is occurring with a very strong ridge over the Pacific Coast, consequently bringing high winds even to the San Francisco Bay Area.
The fire is currently threatening to reach the populated portions of Ventura County including the City of Ventura. Evacuations have been ordered for several cities near the fire such as Santa Paula. In addition, the radar for the National Weather Service Los Angeles office was put into standby mode due to the fire being within a few miles of the radar. Furthermore, the radar site at Vandenburg Air Force has registered the smoke on the radar at about 30 dBZ (decibels with respect to height) which is about the same reflectivity as a rain shower.
The fire is likely to continue spreading at an alarming rate over the next few days due to a continuation of the high winds which is driving dry air to flow over the area. The National Weather Service has issued a Red Flag Warning for the entire Los Angeles and Ventura County areas due to the high winds and low humidity until Friday at the earliest. Evacuation orders have been issued for over 40,000 residents and more orders are expected within the coming days due to the spread of the fire. Southern California Edison reports blackouts affecting over 250,000 customers in Ventura and Santa Barbara Counties due to power lines going down because of the fire. Many schools in Ventura County have been and will remain closed due to the fires.
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© 2017 Meteorologist JP Kalb
Dangerous Wildfires Burn Across Southern California (Credit: NWS Los Angeles/Oxnard, Los Angeles County Fire Department. Photo Credit: NASA Earth)
Discussion: Dangerous Wildfires have spread across parts of Southern California due to Santa Ana winds, low humidity and dry ground conditions. Strong Santa Ana winds across Los Angeles and Ventura counties have caused two large wildfires to break out. Currently the Thomas Fire, Creek Fire and Rye Fire are burning across these two counties. The Thomas Fire has burned 50,000 acres, the Creek fire has burned 11,000 acres and the Rye fire has burned 5,000 acres and is 5% contained. Due to these fires, mandatory and voluntary evacuations have been issued across Southern California. Strong winds are expected to continue in the region until Thursday, along with low humidity values ranging from 6 to 15%, which will keep the risk for fire breakouts high. This is the strongest and longest Santa Ana event of the year. Red Flag Warnings are in effect until Friday across Ventura and Los Angeles. It is important to take steps to protect yourself from the fires and the smoke and to follow the safety orders given by the authorities. It is also important in these weather conditions to exercise caution when using items that could ignite a fire i.e. cigarettes, campfires and brush clearing equipment, as any small fire could spread rapidly. In the photo above taken by NASA Earth, it shows the smoke plumes from the fires.
Santa Ana winds are most often characterized as being hot/dry winds which blow in from the desert towards the coast. These winds tend to occur during the following time frame (between September to May) when the desert is cooler than the Los Angeles basin. For more facts about Santa Ana winds click here! (http://people.atmos.ucla.edu/fovell/ASother/mm5/SantaAna/santa_ana_faq.html)
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© 2017 Meteorologist Shannon Scully