Two residents have been killed and dozens of structures destroyed
Extremely large pyrocumulus clouds tower over bushfires in New South Wales and spread over the Pacific Ocean. Sentinel-2A image, December 31, 2019, processed by @andrewmiskelly.
Very large bushfires continue to rapidly spread through areas of New South Wales and Victoria in southeast Australia, leaving behind hundreds of thousands of burned hectares, blackened forests, and destroyed structures in their wakes.
Victoria
Authorities in Victoria have confirmed that at least 43 structures have been destroyed in the Gippsland region where more than 400,000 hectares (988,000 acres) have burned. Many of the structures were in the Sarsfield and Buchan areas.
The military is being activated to assist firefighters and the public. The Australian Defense Force will deploy Black Hawk and Chinook helicopters, as well as fixed-wing aircraft and Navy vessels for firefighting support and evacuations. Authorities were considering using helicopters to fly in food and other supplies to people cut off by fires and road closures. Over the last few weeks fire aviation specialists from the United States and Canada have arrived in Australia help manage aircraft.
People sought refuge at the Mallacoota boat ramp as the fire approached the town. Instagram by @travelling_aus_family
In Mallacoota, a coastal community popular with vacationers, an estimated 4,000 to 5,000 people were directed to evacuate and take refuge on the beach. They endured dense smoke that turned day into night as the fire spread into the outskirts of the town, sparing most of the buildings as it passed by the area.
Map showing warning areas near bushfires in Victoria, Australia. The areas with a black line and grey fill are designated for evacuation. The red lines indicate “emergency warning”. The width of the largest emergency warning area is approximately 204km (110 miles), east to west. Map by Vic Emergency, Jan. 1, 2020 (local time).
Thousands of people have been left without power in East Gippsland, which AusNet said may not be restored for days.
Country Fire Authority chief officer Steve Warrington said the main fire front has passed the town of Corryong in northeast Victoria near the NSW border after destroying an unknown number of homes on the outskirts of community. An evacuation center was set up at Corryong College.
One resident described the situation in Corryong as “an absolute mess. Fires are everywhere but the town was standing strong.”
New South Wales
At least 40 homes appear to have been destroyed by fires in Conjola Park on the south coast of NSW as the fire burned through on December 31. Many residents fled to the beach.
An unknown number of structures have burned in Cobargo, including some of those along Princes Highway, the main street going through the town.
Before the fire. A scene on the Princes Highway, the main street going through Cobargo, New South Wales. Google Streets image.The same area after the fire, December 31, 2019. Princes Highway, the main street going through Cobargo, New South Wales.
Two men, a father and son, were killed in the Cobardgo area where they had remained to defend their property. Patrick Salway, 29 and his father Robert, 63, perished at the family property at Wandella, about 10 kilometers northwest of Cobargo as the 82,000-hectare (202,000-acre) Badja Forest Road fire approached Monday night.
Police said Patrick’s mother discovered the men’s bodies when she returned to the burnt-out property Tuesday morning.
An excerpt from an article at the Australian Broadcasting Network:
Susanne Lewington, who owns the Breakfast Creek Vineyard in Bermagui, near Cobargo, was forced to evacuate her property at 5 am. She is now at a shelter down the road and does not know if the devastation has reached her property.
“It’s very eerie down here, it’s really smoky, there’s ash everywhere,” she said. “I have no idea if we’ve lost our property. If we have a wind change it could go because we’ve very close to the creek and we’re close to the forest. The sky was black, we only got daylight a few hours ago.”
She said the drought had left her property without any significant water bodies that may have helped dampen the blaze.
“There’s not much left on the property, about 100 ducks, four cattle and 10 sheep, that’s all we’ve got left because I had to sell the rest due to the drought,” she said. “We’ve got no water left so we weren’t able to defend.”
Andrew Crisp, Vic Emergency Mgt Commission in Australia, said they have ordered fire aviation specialists from US and Canada, and firefighters “who can work in remote and arduous conditions”. Presumably in addition to previous orders. At 3:10 in the audio: https://t.co/0mkhgzNQnJ
A NSW engine crew is overrun by a bushfire. Screenshot from the video below. Po
The engine crew from Fire and Rescue New South Wales Station 509 Wyoming recorded the video below showing the moment their truck was overrun by a fire south of Nowra, NSW. The crew was forced to shelter in their truck as the fire front passed through. The video was posted by NSW Rural Fire Service December 31, 2019 local time.
The crew from Fire and Rescue NSW Station 509 Wyoming recorded this video showing the moment their truck was overrun by the bushfire burning South of Nowra. The crew was forced to shelter in their truck as the fire front passed through. #NSWFires#ProtectTheIrreplaceablepic.twitter.com/Hb0yVrefi9
The NSW RFS Commissioner provides more information about the firefighter who was killed when a fire tornado or column collapse flipped his fire engine, causing his death and injuries to two other firefighters. https://t.co/MLVqXPUVSd
Firefighters are protecting 4,000 people at the beach near Mallacoota, Victoria
Map showing warning areas near bushfires in Victoria, Australia. The areas with a black line and grey fill are designated for evacuation. The red lines indicate “emergency warning”. The arrow points toward Mallacoota, Victoria. The width of the largest emergency warning area is approximately 204km (110 miles), east to west. Map by Vic Emergency, Dec. 31, 2019 (local time)
According to numerous reports Tuesday morning local time, rapidly spreading bushfires in northeast Victoria are forcing residents and campers in the Mallacoota area to evacuate the town and take refuge on the coast. Approximately 4,000 to 5,000 people are hunkering down at the beach as a fire approaches the community.
Heavy smoke and huge pyrocumulus clouds created by the fires are putting Mallacoota in near darkness hours after the sun rose Tuesday, December 31.
That ambient winds influence fire behavior is well known. Less understood is how fire influences the winds and how the feedback affects the fire’s evolution.
One freeze-frame moment in a simulation illustrating the dynamics of wind fields in a vertical plane as a wildfire approaches — towers and troughs. From the video.Towers and troughs, in reality. In this experimental grass fire, the few visible peaks are separated by gaps in which the wind currents sweep downward between the flames and feed the peaks on opposite sides. (Courtesy of Mark Finney, US Forest Service, Missoula Fire Sciences Laboratory.)
The more knowledge firefighters have about the fluid dynamics of wildfires the better equipped they will be to take on the tasks of igniting prescribed fires and suppressing wildfires.
Below is an article written by Rod Linn, who leads development, implementation, testing, and application of computational models of wildfire behavior in the Earth and environmental sciences division at Los Alamos National Laboratory in New Mexico. From Physics Today 72, 11, 70 (2019). https://doi.org/10.1063/PT.3.4350
Fluid dynamics of wildfires
Wildland fires are an unavoidable and essential feature of the natural environment. They’re also increasingly dangerous as communities continue to spread away from urban areas. Unfortunately, a century of wildfire exclusion—the strategy of putting out fires as fast as they start—has led to a significant buildup of fuel in the form of overgrown forests. Continuing to keep wildfires at bay is simply not sustainable. In 2018, nearly 60,000 fires scorched parts of the continental US. California wildfires exemplify what can happen when they burn through communities: In November alone that year fires killed more than 90 people and destroyed some 14,000 homes and businesses.
Decision makers are striving to find ways to manage the consequences of those fires and yet still allow them to thin out dense, fuel-heavy forests and reset ecosystems. Among other things, the goal requires that land managers be able to predict the behavior of wildland fires and their sensitivity to ever-changing conditions. Many factors, including the interactions between fire, surrounding winds, vegetation, and terrain, complicate those predictions.
That ambient winds influence fire behavior is well known. Less understood is how fire influences the winds and how the feedback affects the fire’s evolution. As the fire rages, it releases energy and heats the air. The rising air draws in air below it to fill the gap in much the same way as air is drawn into a fireplace and rises up a chimney. The interaction between rising air and ambient winds controls the rate at which surrounding vegetation heats up and whether it ignites. The interaction thus determines how quickly a fire spreads.
FUEL MATTERS
The influence of the fire–atmosphere coupling is much greater in wildland fires than in building fires. Wildland fires are fed by fine fuels—typically grasses, needles, leaves, and twigs; often, tree trunks and large branches do not even burn. Buildings burn thicker fuels, such as boards, furniture, and stacks of books. The difference matters because fine fuels exchange energy more efficiently with surrounding hot air and gases. In those hot, fast-moving gases, the fuels’ temperature rises quickly to the point where they ignite.
But the converse is also true. Because wildland fuels are primarily fine, they are also efficiently cooled when the surrounding ambient air is cooler than they are. That means that the indraft of air caused by a fire may actually impede its spread. A rising plume can draw cool air over foliage and litter near a fire line and prevent those fine fuels from heating. The grasses just outside a campfire ring are a case in point: They are continuously exposed to the fire’s radiant heat, but the cool indraft effectively prevents them from reaching the point of ignition.
The spread of a wildfire is sometimes conceptualized as an advancing wall of flame that the wind forces to lean toward unburned fuels that then ignite in front of the fire. Although that wall-of-flame paradigm simplifies models of fire behavior, it is not correct. Convective cooling would prevent the wall of flame from spreading by radiation alone, and for convective heating to spread the fire, the wind would have to be strong enough to lean the flame to the point where it touches the unburned fuel. Were that true, the fires would be unable to spread in low-wind conditions because the buoyancy-driven updrafts would keep the flames too upright.
If you were to look upon an advancing wildfire from the front, you would actually see a series of strong updrafts, visible as towers of flame that are separated by gaps, as shown in figures 1 and 2. The towers are regions where the buoyancy-driven updrafts carry heat upward. They are fed by ambient wind drawn into the gaps between them, as described earlier. When the ambient wind is strong enough, it pushes air through the gaps between the towers, but that air is heated as it blows over burning vegetation. The motion of hot gases through the fire line disrupts the indraft of cool ambient air and ignites grasses and foliage in front of the fire. That’s the primary way a wildfire spreads.
A second factor that influences the spread is the shape of the fire line, because different parts of the blaze compete for wind. The headfire, the portion moving the fastest, often has trailing flanking fires that form a horseshoe shape and open up to the ambient wind. Part of that wind gets redirected toward the flanks of the horseshoe. The strength, length, and proximity of the flanking fires to each other thus help determine how much wind reaches the headfire. The narrower the horseshoe is, the larger the fraction of wind diverted to the flanks, the lower the wind speed reaching the headfire, and the slower it spreads.
Another factor to be considered is the spatial arrangements of fuels. The potential for wildfires spreading from the crown of one tree to another is reduced when the spacing between trees increases. In that case more horizontal wind is required for flames to jump between trees. Indeed, removing trees is a common fire-risk-management practice. But the strategy behind it is more complex than just removing fuel. Gaps in a forest canopy also make it easier for high-speed winds above the canopy to reach fires on the ground. So although reducing the number of trees might reduce the crown-to-crown fire activity, it might increase the spread rate of a surface fire.
PRESCRIBED FIRE
In some regions of the US, land managers counter the threat of wildfires and promote ecosystem sustainability by purposefully lighting fires. Carefully controlled, prescribed burns, which clear duff and deadwood on the forest floor, are often lit at multiple locations; fire-induced indrafts at one location influence fires at other locations. For example, a single line of fire under moderate winds might reach spread rates and intensities that are undesirable or uncontrollable, but the addition of another line of fire upwind can influence how much ambient wind reaches the original fire and thus reduces its intensity.
The spread of the upstream fire line, ignited second, is purposefully limited, as it converges on the area downwind where the first fire has burned off fuel. Practitioners can manipulate the flow of wind between fire lines by adjusting the spacing between ignitions. Fire managers might tie the various ignition lines together—reducing the fresh-air ventilation, increasing the interaction between the lines, and causing fire lines to rapidly pull together—to give themselves more control over the spread.
The interaction between multiple fire lines can even stop a wildfire in its tracks. When firefighters place a new fire line downwind of a fire, they often hope that the indrafts will pull the so-called “counter fire” toward the wildfire and remove fuel in front of it. Unfortunately, the maneuver requires a good understanding of the wildfire’s indraft strength. Too weak an indraft could turn the counter fire into a second wildfire.
After realizing the huge significance of the wind interactions in wildfires over the past two decades, the science community is striving to better account for them. Those efforts should improve predictions of how a wildfire will behave in various conditions. To that end, some researchers, including me, use computer models to explicitly account for the motion of the atmosphere, wildfire processes, and the two-way feedbacks between them. Others perform experiments at scales ranging from meters (such as in wind tunnels) to kilometers (such as in high-intensity fires on rugged topography) for new insight on the nature of those fire–atmosphere interactions or to confirm existing models.
The [above] simulation illustrates the dynamics of wind fields in a vertical plane, located at the white horizontal line, as a wildfire approaches it. The colors mark the speed u of the wind perpendicular to the plane, with red indicating motion toward the viewer (out of the screen), and blue indicating motion away from the viewer. As the clip shows, the fire starts to influence the winds long before it reaches the plane, and the wind patterns change in scale and character as the fire approaches. As the fire crosses the plane, the towers and trough flow patterns become apparent. Some locations show strong upward motion, whereas others have strong horizontal or even slightly downward motion. The colors on the ground surface illustrate the convective cooling (blue) that occurs as a result of the movement of cool air over the fuel— grasses in this simulation—and locations in front of the fire where the fuels are being convectively heated (red).
It is believed that the truck rolled when hit by extreme winds associated with the fire
Map showing the Green Valley Fire, produced at 4 a.m. local time December 31, 2019. The fire is 43 miles east of Albury, NSW. Map by Victoria Emergency.
UPDATE: The New South Wales Rural Fire Service has identified the firefighter killed at the Green Valley Fire as Samuel McPaul from the Morven Brigade of the Southern Border Team. Today Service flags will be flown at half-mast as a mark of respect.
Samuel McPaul. Photo supplied by NSW RFS.
The New South Wales Rural Fire Service confirmed December 30 that a RFS volunteer firefighter died Monday evening near Jingellic. Two other firefighters on the same truck suffered burns and were transported to a hospital.
The firefighters were working on the Green Valley, Talmalmo Fire, approximately 70km (43 miles) east of Albury NSW when it is believed that “the truck rolled when hit by extreme winds associated with the fire” according to information released by the RFS. The incident occurred in NSW near the Victoria/NSW border 150km (93 miles) southwest of Canberra.
A second vehicle working in the same area was also blown over and the firefighter on board is being treated in a hospital.
Our sincere condolences go out to the family, friends, and coworkers of the firefighters.
New South Wales has been experiencing numerous large bushfires for the last month and in recent days Victoria has as well.
On the day two firefighters were killed on the Carr Fire near Redding, California July 26, 2018 winds associated with the fire were estimated at 136-165 mph (EF-3 tornado strength), as indicated by wind damage to large oak trees, scouring of the ground surface, damage to roofs of houses, and lofting of large steel power line support towers, vehicles, and a steel marine shipping container. Multiple fire vehicles were damaged by flying debris and had their windows blown out.
Map showing the Green Valley Fire
Thanks and a tip of the hat go out to Tom. Typos or errors, report them HERE.
