Researchers flying near smoke plumes over a large wildfire found extreme updrafts up to 130 mph and downdrafts reaching 65 mph. Operating radar and other sensing equipment in a small plane, one of the scientists was injured as the aircraft experienced a dramatic vertical displacement as it penetrated a 34-meters-per-second updraft in a plume over a flank of the 2016 Pioneer Fire in Idaho.
This is the first time the vertical velocity structure of a pyroconvective updraft has been viewed in such detail. The research showed that intense fires can produce updrafts that rival or exceed those in tornadic supercell thunderstorms.
An unexpected finding was that the updrafts strengthened with height above the surface, at least initially, challenging the assumption that they should decelerate with height.
The updrafts, the strongest ever documented, can be a hazard to aviation since they do not always show up on pilots’ weather avoidance radars, as discovered during a Qantas flight over a bush fire in Australia in January, 2020. Passengers experienced turbulence and darkness as the airliner entered the pyrocumulus cloud.
"There was one guy sort of swearing … I heard people down the front vomiting."
Another passenger said it was "the scariest flight" she had taken.
These findings are presented in a paper published September 9, 2020 written by B. Rodriguez, N. P. Lareau, D. E. Kingsmill, and C. B. Clements.
When crews of wildland firefighters in a remote area have to quickly move to a safer location due to an approaching flaming front, they hike on what they call an escape route to get to a safety zone where they can be out of danger without having to deploy their fire shelters. An average of 11 firefighters die each year while fighting fire. Of these deaths, about 44 percent are caused by entrapment or burnover events.
A key to moving to a safety zone is the travel time. Underestimating the required time can be fatal, in the worst of circumstances. That may or may not have been one of the many factors involved in the deaths of 19 firefighters on the 2013 Yarnell Hill Fire in Arizona.
Firefighters know how long it takes them to hike the three miles within less than 45 minutes while carrying 45 pounds as required by the Pack Test, or Work Capacity Test. From that it’s pretty easy to calculate their miles per hour. But that is on flat ground, a situation that is not always the case when escaping from a wildfire. Throw in steep uphill or downhill slopes, and the times will increase.
A research paper that was published July 8, 2019, written by Michael J. Campbell, Wesley G. Page, Philip E. Dennison, and Bret W. Butler. It is titled, Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity.
A new study uses a different database for the speed at which fire crews can hike. It is titled, “Modeling Wildland Firefighter Travel Rates by Terrain Slope: Results from GPS-Tracking of Type 1 Crew Movement.” (download, 2.3 Mb)
As the name implies, instead of using public crowd-sourced hiking speed data, the researchers issued GPS units to nine Type 1 Interagency Hotshot Crews in the Spring of 2019. Nine of the 11 participating IHCs received seven GPS units each, and the other two received 20 GPS units each. In addition to the GPS units, crews were provided with data collection sheets and armbands to carry the GPS units.
Using data collected by firefighters — a uniquely physically fit population that usually carries heavy loads while moving — provides a set of robust, adjustable travel rate models built from instantaneous travel rate data that can be applied in a variety of contexts.
The data was collected while on training hikes. Rather than rely on GPS for elevation, which is not always accurate, only locations having the more accurate lidar data were used.
The tables below are from the research paper.
Here is an excerpt from the paper:
“The effects of the slope on the instantaneous travel rate were assessed by three models generated using non-linear quantile regression, representing low (bottom third), moderate (middle third), and high (upper third) rates of travel, which were validated using k-fold cross-validation. The models peak at about -3o (downhill) slope, similar to previous slope-dependent travel rate functions. The moderate firefighter travel rate model mostly predicts faster movement than previous slope-dependent travel rate functions, suggesting that firefighters generally move faster than non-firefighting personnel while hiking. Steepness was also found to have a smaller effect on firefighter travel rates than previously predicted. The travel rate functions produced by this study provide guidelines for firefighter escape route travel rates and allow for more accurate and flexible wildland firefighting safety planning.”
The authors of the paper are, Patrick R. Sullivan, Michael J. Campbell, Philip E. Dennison, Simon C. Brewer, and Bret W. Butler.
The extreme heat caused by a large high pressure system in the West has led to an unusual number of fire tornados.
An article in the Washington Post by Matthew Cappucci explains how Neil Lareau, a professor of atmospheric sciences in the department of physics at the University of Nevada at Reno, used detailed weather radar data to make three-dimensional maps of smoke plumes over fires. While it is unusual to have a fire tornado anytime, the data indicates that on at least three fires this year fire tornados have been detected by radar. One was photographed on the Loyalton Fire August 15 about 12 miles northwest of Reno, Nevada. National Weather Service meteorologists who spotted it on radar issued the agency’s first-ever fire tornado warning.
Fire tornados and huge smoke plumes topped by massive pyrocumulus clouds are indicators of extreme fire behavior. There is absolutely nothing firefighters or aircraft can do to slow a blaze under those conditions — and those pyrocumulus clouds seem to be occurring more frequently this year.
The day after the Creek Fire started, its smoke plume grew to 55,000 feet, taller than the tornadic thunderstorms seen in Oklahoma and Kansas in the the spring.
From the Post:
“Anecdotally, this is the deepest that I’ve seen,” said Lareau, who was shocked by the height achieved by the smoke plume. “It’s about a solid 10,000 feet higher than we’re typically seeing with the highest of these plumes.”
Before 2020, only a few fires had ever produced documented fire tornadoes in the United States; now we’re seeing them every week or two. Lareau says the tremendous heights of the wildfires’ clouds, combined with more concerted and astute observation, are factors in the numerous fire tornadoes that have been reported this year. He thinks there may also be some truth to the apparent increase.
“We have a ton of eyes on every fire, looking at every frame, but still, we weren’t seeing these before,” he said. “And we’re seeing all too much of it right now. It’s rather worrying.”
From research conducted by: Schultz, Courtney A. ; McCaffrey, Sarah M. ; Huber-Stearns, Heidi R. , 2019.
Despite broad recognition of its value, managers are not able to use prescribed fire at the levels necessary to improve landscape resiliency in the western United States. A better understanding of policy barriers and opportunities is therefore needed. Limited research suggests that a range of factors constrain prescribed fire implementation including narrow burn windows, air quality regulations, lack of adequate funding and personnel, and other environmental laws. Through interviews conducted in 11 western states, we investigated the degree to which these factors currently act as barriers and the strategies being used to overcome key barriers for prescribed fire application on United States Forest Service (USFS) and Bureau of Land Management (BLM) lands. We asked the following questions: (1) What are the most significant policy barriers to prescribed fire on USFS and BLM lands in the West? (2) What are potential opportunities and mechanisms for change?
The barriers to prescribed fire that were most frequently identified by our interviewees were lack of adequate capacity and funding, along with a need for greater leadership direction and incentives to apply prescribed fire. Interviewees emphasized that owing to a lack of incentives and the prevalence of risk aversion at multiple agency levels, active prescribed fire programs depend on the leadership and commitment of individual decision-makers and fire managers. Barriers related to policy requirements tended to be significant only in specific locations or situations, such as smoke regulations in the Pacific Northwest or protecting specific threatened and endangered species.
Our findings highlight the importance of contextualized investigation into policy barriers and the role of collaborative and multilevel governance approaches for addressing complex land management challenges. This research has broader implications for fire and natural hazard management. It is important in a complex governance system to continue to assess where barriers lie and how they can be addressed. Challenges will change over time, requiring a nuanced and ongoing contextual approach to understanding impediments to improving practice.
Findings support previous survey work that found that capacity is a major limitation for applying prescribed fire. We found less support for previous findings that air quality regulation is consistently a significant barrier, except in specific locations.
Interviewees emphasized that owing to a lack of incentives and the prevalence of risk aversion at multiple agency levels, active prescribed fire programs depend on the leadership and commitment of individual decision-makers and fire managers.
Successful approaches rely on collaborative forums and positions that allow communication, problem solving, and resource sharing among federal and state partners, and that facilitate dialogue between air-quality regulators and land managers.
Although not a focus in the present work, interviewees also discussed other barriers to burning, like drought conditions, short burn windows, and the presence of challenging landscape conditions, such as the presence of invasive cheat grass (Bromus tectorum), that limit their ability to conduct prescribed fire.
Researchers developed a COVID-19 epidemic model to highlight the risks posed by the disease during wildland fire incidents. A paper published August 1, 2020 details how they started with actual mobilization data from the Resource Ordering and Status System (ROSS) for three 2017 wildfires that had different characteristics — the Highline Fire, which burned for much of the summer but the personnel peaked early in the effort; the Lolo Peak Fire, which spanned July through September and had a relatively symmetric mobilization and demobilization phase; and the Tank Hollow Fire, which was shorter than the other two, and had fewer personnel throughout the incident.
The variables that were modeled included the number of infected persons arriving at a fire, the rate of secondary infections caused by an infected person, infection fatality rate, and the number of people assigned to the fire each day.
There are also many other variables that are difficult or impossible to account for, such as social distancing at the incident, protocols followed by personnel in the weeks before the assignment, how much time they spend at fire camp, mode of travel to and during the incident, wearing of masks, testing before and during the incident, working remotely, and others.
Below is an excerpt from the study:
“Models are, by definition, an abstraction of reality and are subject to the accuracy of the parameters. Wildfires and the COVID-19 pandemic are each complex dynamic phenomenon, and the combination of the two produces great uncertainty. Therefore, we stress the limits of our model and highlight the qualitative results of the analysis rather than the estimated numbers.
“In this study, we focused on two sources of case growth on an incident. The first is the introduction of infection by personnel arriving on an incident. As the fire grows and the incident becomes more complex, resource orders will be filled by available personnel, some of whom may come from other counties or states. Given the variation in the COVID-19 prevalence around the country at any given point in time, the firefighters from different areas will introduce variable risk to the camp. While current policies require or request symptomatic individuals to report their conditions and inform supervisors, evidence suggests that many infected people may experience very mild symptoms. These asymptomatic individuals may remain infectious for weeks, perhaps posing the greatest risk of infection through a camp. The combination of exposure risk posed by the high turnover of personnel coming from a large number of places in concert with the exposure risk due to non-quarantined infectious individuals highlights the potential merits of developing testing strategies for early identification, which could include testing asymptomatic individuals without known or suspected exposure. The utility of such testing strategies is conditioned by the availability, timeliness, and reliability of viral tests, and the optimal testing strategy design could be the subject of future research.
“The second source of case growth on an incident that we examined was the spread among personnel while assigned to the fire. In the event that personnel arrive at an incident exposed or infected, their level of interaction with others will determine the rate of transmission within the camp. The rate of transmission will depend on the level of interaction between the personnel at the incident and the nature of those interactions. Under normal circumstances, personnel may gather in large groups, for example, for briefings or meals. These interactions are similar to potentially infectious interactions in the general public that public health agencies have deemed ill-advised. Some of these interactions could be made less risky using current social distancing and mitigation recommendations; for example, masks appear to provide a barrier to the spread of SARS-CoV-2. Recognizing that a range of mitigations is already being planned or put into place by incident management personnel, these analyses provide a proxy for a business-as-usual baseline as a point of comparison.
“We studied two types of interventions corresponding to the two types of source growth identified above: the screening of personnel arriving at the incident to address the case growth by the entry of the virus and the spread from non-quarantined infectious individuals, and social distancing measures within the fire camp to address the case growth from the spread among individuals in the camp. While both interventions mitigate transmission and lead to fewer cases, screening measures are relatively more effective on shorter incidents with a frequent resource turn over. In contrast, social distancing measures are relatively more effective on prolonged campaigns where most of the cases are due to transmission within the community.”
The researchers found that a large, long-duration fire with a hundreds of personnel is likely to have more infected individuals and fatalities than shorter-duration incidents with fewer individuals. Under COVID-19 conditions, a fire like the 2017 Lolo Peak Fire south of Missoula could have, according to their modeling, from less than 1 or up to 13 fatalities from the disease.
The Bureau of Land Management will open a 30-day period during which it will accept public comments on their plans to remove some steps that are required before cutting timber following a fire.
The agency intends to no longer require Environmental Impact Statements or Environmental Assessments on what they call “salvage” operations of less than 5,000 acres — cutting dead or dying trees which can result from insects or wildfires. They would use a Categorial Exemption (CX) to skip some environmental review steps that are usually required.
The BLM’s press release about their plans did not include information about how the public could comment, just that, “[A] a public comment period on the proposed CX closes 30 days after the proposal publishes in the Federal Register. The BLM will provide additional information about when and how to comment when the proposed rule is published. ”
The BLM has completed a review of scientific literature and previously analyzed and implemented actions and found no evidence that salvage harvest at the levels proposed would have a negative effect on forest health. To the contrary, removing dead and dying trees can accelerate forest succession and benefit native wildlife species that rely on successional habitat, while reducing the potential for catastrophic wildfires.
“Some of the impacts we have outlined may be different from or additional to the effects of traditional forms of logging that are not preceded by large, natural disturbance events. This is because the conditions preceding, during, and after salvage logging may differ from those in areas subject to traditional logging. Moreover, the ecological benefits derived from large-scale disturbances (such as the creation of charred trees and coarse woody debris) can be lost or severely diminished by salvage operations for decades and even centuries (Lindenmayer & Ough 2006). These problems have often been overlooked or poorly understood by conservation biologists, foresters, and other natural resource managers. In some cases salvage impacts may have been so substantial that past interpretations of ecosystem responses to natural disturbance may need to be reexamined. That is, ecosystem processes and biotic responses may have been more influenced by salvage logging than by the initial natural disturbance event. This may be true for hydrological regimes in the northeastern United States following the 1938 hurricane (Foster et al. 1997), aquatic macroinvertebrates in the western United States (Minshall 2003), and arboreal marsupials in the forests of Victoria, Australia, after the 1939 and 1983 wildfires (Lindenmayer et al. 1997).
“Whereas most documented effects of salvage logging are negative from an ecological standpoint, others can be neutral or positive, depending on the response variables measured. Effects are likely to vary over time and among and within vegetation types in response to the type, intensity, and periodicity of natural disturbance and disturbance by salvage logging. Therefore, there can be no generic recipes for salvage logging that can be uncritically applied in all landscapes.
“Perhaps one of the problems associated with the lack of appreciation of the impacts of salvage logging lies in the terminology itself. Dictionary definitions of the term salvage associate it with “recover or save” or “saving of anything from loss or danger” (e.g., Delbridge & Bernard 1989). Although salvage logging removes wood from burned areas, such practices generally do not help regenerate or save ecosystems, communities, or species (but see Radeloff et al. 2000) and often have the opposite effect. Hence, in many respects, the term salvage is inappropriate and misleading from ecological and conservation perspectives. An alternative term might be postdisturbance logging.”