Fire Regime

Five Years of Wildfires Devastate Lake County, an Insurance Risk or Opportunity?

With Lake County now holding the title of the largest fire in California’s recorded history, the Ranch Fire of the Mendocino Complex, it leaves one to wonder what exactly it is that’s producing the conditions for these enormous fires to thrive in this area. It has been estimated that in the last 5 years, over 55 percent of the surface area in Lake County has burned in wildfires. It has become an unfortunate understanding of the residents that have chosen to settle in this county that it is not if a big fire will occur, but rather, when will the next one occur. In regards to wildland fire, there are three main elements that are known to have the most impact on fire behavior: weather, topography, and fuels. Unfortunately for Lake County, the area has all three of these influential factors working against the fire regime of the area.

Fire History

This map displays all of the fires inside a 1 mile buffer of Lake County that reached over 100 acres since 2012.

Topography

Lake County is located in the Coastal Range of northern California, on the west side of the Sacramento Valley. Lake County resides in a mid-altitude area that is high enough above sea level to be above the influence of the marine layer, but not high enough in the mountains to feel impacts of the cooler upper atmospheric air. In  the center of the county rests Clear Lake, which is the lowest point in elevation throughout the entire area. Surrounding this geographic feature are seemingly endless mountains, hills, and valleys extending in every direction until they arrive in the northern reaches of the Mendocino National Forest. These areas of tremendous elevation variation are where fires tend to thrive. Fires are able to take advantage of these slopes to preheat the fuels up-slope from the fire, while simultaneously utilizing the convection column of hot gasses being funneled through these drainages to fuel the fire’s spread.

Weather

The local weather patterns of Lake County tend to have a negative impact on fire behavior in the area. During fire season, the predominate winds blow from the northwest, with the occasional shift coming from the northeast, bringing the warm and dry air from the northern portion of the Sacramento Valley into the area. On the extreme side of the spectrum are Foehn Wind events that cause extreme fire behavior when they occur. Foehn or “sundowner” winds bring hot, dry air into the area, with an uncharacteristic down-slope flow that allows fire to spread at unfathomable rates. When these events occur, fires can continue to burn actively through the night which is usually the time when fire behavior begins to moderate.

Fuels

Lake County is relatively diverse in terms of the vegetation species throughout the county’s boundaries. Nearly every major fuel type that exists is contained within the county including grasslands, oak woodlands, brush, mixed conifer forests, and hardwood forests. Due to the wide spectrum of vegetation species here, fires can range from low intensity grass fires, to extremely high intensity forest fires. The map below depicts the vegetation classifications throughout the entire county. Starting in the southern areas of the county, the predominate fuel type is comprised of annual grasses and oak woodlands. As you move up in elevation on both the east and the western side of Clear Lake, the fuel type primarily changes to a chaparral-based fuel bed. Progressing further north into the Mendocino National Forest, the dominant fuel type changes once again to one of a heavy timber, mixed conifer, and hardwood forested area.

Vegetation

This map depicts the vegetation types throughout Lake County. Visualizing this data clearly shows the predominant vegetation type shifting as you progress north, from the southern border of the county.

The reasons above are all variables in what seems to be a devastating half-decade of fire history for the Lake County region. The complicated wildfire situation in this area has been influenced by the recent years of drought, which has decreased the available moisture in the region, drying out the vegetation and furthering their susceptibility to fire. Lastly, Lake County has had an increase in residency due to increasing interest in the Napa/Sonoma Wine country. With more human influence comes the increased probability of fires igniting.

Insurance risk or Opportunity?

Will this information impact insurance companies when considering existing policies, writing future business, or even adjusting premium rates in this county? Does this amount of fire activity in such a small time frame deter insurance carriers from writing new business in these areas? These recently charred areas should be considered as an opportunity to obtain new clientele due to the diminished risk from wildfire in the upcoming years based off the lack of vegetation. Some factors to take into account would be the return interval rate of fire in each of these fuel types. This knowledge would give an estimation of how long that specific site will have before it is ready to burn if the new vegetation is the same species. For example, Chaparral brush which, is a large portion of Lake Counties fuel, has a highly variable fire return interval ranging from 10 to over 100 years. If properly managed an individual could easily keep fire from returning to the landscape for a long period of time. Another advantage of insuring homeowners in recent burn areas, is the opportunity to educate them with advice on how to manage the vegetation around their home as it begins to regrow. This would in turn, promote defensible space around the structure, and give the client a piece of mind that their insurance company cares for their home, while simultaneously protecting the insurers investment.

Sources

http://www.lakecountyca.gov/Assets/County+Site/Fire+Safe+Council/cwpp/eco.pdf

http://www.lakecountyca.gov/Government/Boards/lcfsc/LCCWPP.htm

http://www.latimes.com/local/lanow/la-me-lake-county-fire-epicenter-20180814-story.html

http://www.californiachaparral.com/fire/firenature.html

https://www.weatheronline.co.uk/reports/wxfacts/The-Foehn-foehn-wind.htm

https://www.nfpa.org/-/media/Files/Training/certification/CWMS/S-190-Intro-to-Wildland-Fire-Behavior.ashx?la=en

Autumn and Santa Ana Winds

Fall Means Santa Ana Winds

Annually, the onset of the fall and winter seasons brings the highest chance for Southern California’s famed Santa Ana winds. An unusually strong and persistent Santa Ana event was the largest factor in the spread of last year’s Thomas fire in Ventura (now second largest in size to Mendicino Complex). Much of Southern California experienced an on-and-off Santa Ana wind event for a little over two weeks, which contributed to the Thomas Fire burning a hot lap around Ojai and into Santa Barbara.

What Are Santa Ana Winds?

Typically Santa Ana air mass conditions are brought on by high pressure inland and lower pressure off the Pacific Coast which brings very hot and dry weather along with strong, down-slope winds.  Santa Ana winds typically happen between September and May, in the winter months. We think this UCLA FAQ outlines Santa Anas the best. In the past, the critical fire weather conditions that accompany Santa Ana winds turn the typically dry chaparral of Southern California into explosive fuel.  Some of the country’s costliest fires in history have taken place in these conditions.

Santa Ana Winds

Santa Ana Winds derive from High Pressure in the Great Basin

The Outlook This Fall

Typically, a weather event occurs by mid-September that brings moisture to regions experiencing significant fire activity which allows for the western fire season to begin to decrease in activity. All signs point to a normal seasonal progression including a transition from ENSO Neutral conditions to El Niño, therefore such an event is expected. Most regions will exit the fire season at this point, but only a brief lull is expected across California before it enters its fall fire season by October and November. Given ongoing dryness in the fuels, the fall season may very well be robust across portions of the state. Fortunately for the drought situation, Meteorologists are expecting an El Niño cycle to begin affecting the area with rains by November.  In the meantime, as the tropical air mass that has brought this summer’s rain gives way to autumn’s Pacific air mass, a few Santa Ana events should precede the El Nino’s wetting effect. 

 

Mendocino Complex Fire Progression Map

The Mendocino Complex: An Update on Current Conditions

Mendocino Complex Fire Summary

The Ranch fire, which is being managed as a part of the Mendocino Complex, Started on July 27th on the north bound side of highway 20, east of Lake Mendocino. Fuels in this area consisted of grass, brush and Oak trees. The grasses along the highway led the fire rapidly becoming established and making a run upslope to the east. Due to winds in the area the first resources on scene were not able to catch this fire in its initial stages.

The Second fire being managed under the Mendocino Complex is the River Fire. The River Fire began on the east side of Old River Road, nearly 7 miles southeast of Ukiah, CA. Similar to the Ranch fire, the River Fire began in grasses and became rapidly established making a run up slope to the Southeast. The two incidents spread in a very similar manner for the first 3 days due to both fires burning in identical fuel types, and experiencing the same wind conditions during the initial attack phase. This is depicted very well in the fire progression map provided by the incident management team below.

Mendocino Complex Fire Progression Map

Fire progression map displaying the similarities in burn patterns for the initial 3-4 day period of these campaign fires.

Mendocino Complex as of August 16, 2018

The type-1 incident management team has been making significant progress with suppression efforts on these two fires. Currently the River fire remains with 48,920 acres burn and is 100 percent contained. The Ranch Fire has now surpassed the Thomas in acreage and claimed the title of California’s Largest Wildfire in recorded history. The Ranch Fire is currently 317,117 acres with 69 percent containment. The main influence of the Ranch Fire during the upcoming operational will be winds speeds. With the predominant winds coming from the west, the fire will continue push east. As these winds diminish this evening the primary driving factor of fire spread will switch to the local topography. This will likely change the direction of spread to the northeast. With the fire continuing to spread to the Northeast, there will be no shortage of fuel as it furthers its destruction of the Mendocino National Forest. Fire crews have constructed containment lines in this area and are preparing for a firing operation if the opportunity presents itself.

Aerial Imagery, Carr Fire, Mendocino Complex

This image shows both the Mendocino Complex and the Carr fire’s smoke column from a satellites view.

Mendocino Complex Fire Facts

  • As of: August 16th, 2018
  • Location: Clear Lake, CA
  • Size: 366,037 acres
  • Containment: 76%
  • Fire Behavior: Moderate Fire spread through heavy timber and brush in steep, rugged terrain.
  • Structures Threatened: 1025
  • Structures Destroyed: 147 Residences/118 Other
  • Structure Damaged: 13 Residences/ 23 Other
  • Evacuations: Are in place
  • Incident Page: http://www.fire.ca.gov/current_incidents/incidentdetails/Index/2175
  • News Article: ABC 7
RedZone Disaster Intelligence

Wildfire 101: Dead Fuel Moisture

Drought Conditions Worsening in California

This time of year in Southern California lacks significant rainfall; with fire activity at its peak a common term heard is “fuel moisture”. A light year in terms of rainfall has allowed Southern California to fall back into a significant drought. The wetting rains of two winters ago seem a distant memory. While that winter helped the state’s dried up reservoirs the lack of wetting rains since the beginning of the year has impacted the region and state’s fuel moisture levels, exacerbating the wildfire situation.

nationwide DFM

Nationwide 1000 Hour Dead Fuel Moisture as of August 12th, 2018

What is Dead Fuel Moisture?

Drought means there is increased potential for significant wildfire due to dangerous levels of dead fuel moisture. As explained by NOAA, fuel moisture is a measure of the amount of water in a potential fuel, and is expressed as a percentage of the dry weight of that fuel.  So if leaves and downed trees were completely dry in a given area, the fuel moisture level would be 0%.

When fuel moisture content is high, fires do not ignite readily, or at all, because most of the fire’s heat energy is used up trying to evaporate and drive water from the plant in order for it to burn. When the fuel moisture content is low (like in drought-stricken Southern California), fires start more easily and can spread rapidly as all of the heat energy goes directly into the burning flame itself. When drought is extreme and the fuel moisture content is less than 30%, that fuel is considered to be dead, giving us the “dead fuel moisture” designation.

Classifying Dead Fuel Moisture

The United States Forest Service which manages a nationwide fuel moisture index, classifies fuel moisture based on two metrics:  fuel size and time lag.

  • Fuel size refers to the actual physical dimensions of the fuel (i.e. the diameter of downed logs or branches).
  • A fuel’s time lag classification is proportional to its diameter and is loosely defined as the time it would take for 2/3 of the dead fuel to respond to atmospheric moisture.  For example, if a fuel had a “1-hour” time lag, one could expect its wildfire susceptibility to change after only 1 hour of humid weather.  Fuels with 100- or 1000-hour time lags would be expected to be much less resistant to humidity.

Fuel moisture is dependent upon both environmental conditions (such as weather, local topography, and length of day) and vegetation characteristics.  The smallest fuels most often take the least time to respond to atmospheric moisture, whereas larger fuels lose or gain moisture slowly over time.

The classifications of the Forest Services’s index (also known as NFDRS) are as follows:

Dead Fuel Moisture

The Dead Fuel Moisture Time Lag Classes as defined by the United States Forest Service

 


Source(s):

https://www.ncdc.noaa.gov/monitoring-references/dyk/deadfuelmoisture

http://www.nwcg.gov/glossary/a-z

http://www.wfas.net/index.php/dead-fuel-moisture-moisture–drought-38

fire on the horizon

Do the First Five Feet Matter Most?

Experiments, models, and post-fire studies have shown homes ignite during wildfires due to the condition of the home and its surroundings, up to 200′ from the foundation. The last couple of years, fire researchers have found more and more cases of homes burning down due to combustibles directly linked (first five feet) to the structure. Specifically, embers and small flames from low intensity surface fires are igniting adjacent combustibles which are, in turn, igniting homes. Therefore, the Home Ignition Zone receiving the most attention lately, is the area within 0-5 feet of the home.

H I Z

The Home Protection Zone as suggested in the Wildfire Home Assessment Checklist published by Insurance Institute for Business & Home Safety (Source: http://disastersafety.org/wp-content/uploads/wildfire-checklist_IBHS.pdf)

First Five Feet Defined

The actual home, including roof and deck, along with the area within five feet of the zone makes up what the NFPA refers to as the “Immediate Zone”. According to the site, science has proven that this is the most important zone to take action on as it is the most vulnerable to embers and therefore home ignition. The group also provides a few suggestions for this zone which will help the survivability of a home during a wildfire event.

  1. Clean roofs and gutters of dead leaves, debris and pine needles that could catch embers.
  2. Replace or repair any loose or missing shingles or roof tiles to prevent ember penetration.
  3. Reduce embers that could pass through vents in the eaves by installing 1/8 inch metal mesh screening.
  4. Clean debris from exterior attic vents and install 1/8 inch metal mesh screening to reduce embers.
  5. Repair or replace damaged or loose window screens and any broken windows Screen or box-in areas below patios and decks with wire mesh to prevent debris and combustible materials from accumulating.
  6. Move any flammable material away from wall exteriors – mulch, flammable plants, leaves and needles, firewood piles – anything that can burn. Remove anything stored underneath decks or porches
six keys to the first five feet

The six keys to safety in the 0-5 foot zone


Sources:

Disaster Safety Organization

NFPA

NFPA Xchange Blog

Wildfire 101: United States Fire Regimes

With climate change becoming more prevalent in recent years, science has been looking for ways to examine how changes to the earth’s present and past environment will affect the way wildfires will burn in the future. Fire regimes are a great start for looking into how climate change will affect the behavior, occurrence, and characteristics of how wildfires burn. According to Firescience.gov, the definition of a fire regime is “In general a fire regime characterizes the spatial and temporal patterns and ecosystem impacts of fire on the landscape”. Many characteristics of the environment go into shaping the fire regime in any given area.

Fire Regime Factors

Of the many factors within the environment that come into play when creating fire regimes, there are two critical aspects that shape how fires burn the most. The first of these two crucial factors is the dominant vegetation type within the ecosystem. Chemically, fires need three ingredients to burn, oxygen, heat, and fuel (vegetation). Therefore, if any one of these is removed an ignition cannot occur. History tells us that the type of vegetation is a key factor because of how large the difference in fire behavior is between fuel types. A second major factor involved in formulating a fire regime for a certain area is climate. The local weather patterns in an area have a huge impact on how a fire will burn through the geographic region in question.

fire regimes 48 states

Lower 48 United states classified into fire regime zones.

In the formation of these regimes, fire ecologists have used data regarding vegetation classifications pertaining to the dominant vegetation type in the area. This is combined with historical fire information such as, fire perimeters, and fire conditions to get an understanding of how fire acts within the landscape. Lastly, fire return interval rates are used to determine, on average, how long it will take to have a fire reoccur in a landscape that has burned.

Fire Regime Classification

Over the years fire ecologists have made many attempts at creating fire regimes for the United States using a variety of weighted combinations and factors similar to what was mentioned above. Recently, one group has emerged with the most thorough and up to date classifications of fire regimes. LANDFIRE has created a robust model that incorporates the historical aspect of past fires, and what is projected for the future of the landscape. This will provide a base platform for future research to see how wildfires occurrence, and characteristics are changing as the climate continues to change. Below is a map of the United States classified by each regions respective fire regime as well as, the legend that explains what each level of classification means for that specific area.

fire regime table

This table shows the characteristics behind the fire regime classifications listed on the map above.

Sources:

https://www.firescience.gov/projects/09-2-01-9/supdocs/09-2-01-9_Chapter_3_Fire_Regimes.pdf

https://www.landfire.gov/fireregime.php

https://www.fs.fed.us/database/feis/fire_regime_table/PNVG_fire_regime_table.html

helo wildfire

It’s Prescribed Fire Season

 

In many wildland areas, smoke can often be seen throughout the winter. More than likely, this is not due to uncontrolled wildfire, but rather prescribed fires that are started when the weather is less conducive to catastrophic burns, allowing firefighters and crews to prepare for when wildfire season picks up again.

 

30230_628921240365_2148150_n.jpgA Rx fire (controlled pile burning) I helped ignite in Golden Hills near Tehachapi, CA

 

Prescribed fire is one of the most effective mitigation concepts for reducing the outbreak and spread of wildfires. SmokeyBear.com defines prescribed fire as the controlled application of fire by a team of fire experts under specified weather conditions that help restore health to fire-adapted environments.  Prescribed fires can sometimes be confused with “backfiring” or “controlled burning” which typically refer to different types of prescribed and controlled fires. In many cases by safely reducing excessive amounts of brush, shrubs, and trees, prescribed burning can help reduce the catastrophic damage of wildfire on wildlands and surrounding communities.

In the Golden Hills photo above, the piling and burning of excess fuel was intended to make the fire road safer (this technique is sometimes called road brushing) and also to provide a fire break between Hwy 58 (a major thoroughfare) and the densely populated Golden Hills community.

A recent article by UC Berkeley News calls on more prescribed burns to help reduce the risk of large wildfires from the tree death epidemic across the Sierra Nevada Mountains. Dead trees in the region have left a huge dead fuel load across the area, and could feed massive fire with dangerous and unpredictable fire behavior when the hot and dry conditions return this summer. Prescribed fires, along with mechanical thinning and removing of trees, help reduce fuel loads enough to limit the risk of wildland fires spreading to nearby communities.

Read our past article about tree mortality to learn more here.

Sources:

Berkeley News

Fox5 Prescribed Burn Article

Editor’s Note: This article was originally published in January 2016 and was updated in January 2018

SmokeJumper Fire

Smokejumpers: Flying into the Danger Zone

Introduction

In the Wildland Firefighting community Smokejumpers are widely regarded as one of the most prestigious positions in the fire service. Smokejumpers are transported to fires in fixed wing aircraft, where they jump out at altitude and parachute down to the fire area. This seemingly wild process reduces response time to remote areas of the forest, and has allowed firefighters to access and attack fires long before heavy equipment could arrive. These seasoned firefighters utilize their vast fire knowledge, coupled with hand tools and chainsaws, to build a fire break around these newly sparked isolated incidents. Smokejumpers have a long history of fighting fire in some of the most secluded forested areas of the United States.

SmokeJumper Landing

Smokejumper landing in a very open, and safe landing zone.

History of the Smokejumpers

Beginning in 1917, the United States Forest Service has been utilizing aircraft as a tool for fighting wildland fires. The first experiments in aviation consisted of dropping containers filled with water onto established wildfires in the hopes of achieving extinguishment. Some of the containers tested in these initial drops consisted of, 5 gallon tin cans, paper bags, and 8 gallon oak beer kegs, all of which proved to be failures. In 1934, T.V Pearson proposed using the relatively new technology of parachutes as a means of transportation for firefighters to be dropped near inaccessible wildland fires. This idea was quickly rejected by the government after a few demonstration jumps. In 1939 attention returned again to T.V. Pearson’s idea of parachuting into a fire. During this year 60 jumps were made into rough terrain simulating what it would be like to parachute into a fire area. In 1940, a crew of 6 Smokejumpers was put together in Winthrop, Washington, and another crew of 6 was staffed flying out of Moose Creek, Idaho. These newly appointed Smokejumpers jumped 9 fires during this first season. The results were finally a success with these crews reaching an early containment on these incidents, saving an estimated 30,000 dollars in suppression costs and property damage. This estimation was triple the cost of the initial investment on the Smokejumping program. Since the success of the first season of the program, Smokejumpers have only become more refined and efficient in their tactics and strategies.

SmokeJumper

Smokejumper leaving the plane with parachute ready to deploy.

Uses and Tactics of the Smokejumpers

                             Today this aerial fire suppression force typically jumps with anywhere from 8 to 16 personnel to an incident. The aircraft is loaded with supplies for the Smokejumpers that are designed for these firefighters to be self-sufficient for anywhere from 48 to 72 hours. The aircraft is also staffed with a spotter, which is typically one or two individuals with extensive smoke jumping experience that plays a support role for the firefighters on the ground. The spotter remains in the aircraft after the Smokejumpers make the initial jump to the fire. The spotter then relays critical information about fire activity, weather conditions, and other pertinent information that the Smokejumpers rely on to do their job safely. Once the firefighters are on the ground, they form and carryout the same duties and roles as a hand crew. They use hand tools and chainsaws to remove fuel, such as vegetation and other combustible material, from the fire’s path.

The Smokejumping program has proven to be one of the most influential and impacting projects related to fighting fires in the wildland. By opening up access to some of the most distant fires in the earliest stages, these potentially devastating disasters have a better chance to be suppressed before they cause any damage to lives or property. As time goes on, Smokejumpers tactics, strategies, and equipment will continue to become more refined and efficient. The combination of some of the best fixed wing and rotary aircraft paired with an elite fire fighting crew remains the most cost effective way to combat fires in desolate areas.

Sources:

https://www.fs.fed.us/fire/aviation/av_library/sj_guide/02_history_of_smokejumping.pdf

https://www.fs.fed.us/blogs/smokejumpers-out-sky-and-fire

https://afs.ak.blm.gov/fireops/fire-operations/smokejumpers-training.php

https://www.fs.fed.us/fire/people/smokejumpers/national-sj-users-guide.pdf

 

Is Wildfire Modeling Behind the Times?

Wildfires are one of the most difficult natural disasters to model. Some argue wildfire modeling is 20 years behind hurricane modeling — and that’s not necessarily inaccurate. Hurricanes occur frequently, take several days to form and can be monitored via satellite. Hurricanes are also enormous and can be over 50 miles in radius. They are not obstructed by buildings and, while complex, are affected by fewer variables than wildfires.

Now, consider wildfires. A wildfire can start in seconds by a lightning strike or a dropped cigarette. Oftentimes, the source of ignition is concealed. A wildfire can smolder for days before significant smoke is reported and others can become destructive in a matter of minutes. Even a small burn — just a few acres — can destroy homes and other structures. On top of that, wildfires are affected by a myriad of factors from roads to fuel moisture and type to relative humidity. Sometimes, wildfires are so short-lived that these variables are not recorded; other times, a wildfire covers so many ecosystems that each area of the fire is impacted differently.

File:Propagation model wildfire.png

RedZone Improvements to Wildfire Modeling

Neither hurricane modeling nor wildfire modeling is an easy task. However, wildfires present so many distinct challenges that it’s difficult to even compare the two types of events. Fortunately, wildfire modeling has come a long way in recent years and we at RedZone have made it a priority to make wildfire modeling more accurate than ever before.

Take the Waldo Canyon Fire in Colorado, for example. A simplistic wildfire model didn’t account for many of the devastating factors that ultimately destroyed properties. One of these factors was ember showers, which caused homes to burn that were outside of the assumed danger zone. RedZone’s solutions, developed by expert wildfire analysts, take into account these lesser-known variables that can have devastating effects on properties during a wildfire. RedZone wildfire modeling also takes several scenarios into account at the same time. For example, it asks: If the wildfire goes in direction A, how far will it go? If the wildfire goes in direction B, how far will it go? And so on. By taking into account the likelihood and severity of every possible scenario, and every variable that goes with each, we are reaching a new standard for wildfire modeling.

RedZone looks at wildfire modeling from a loss-prevention perspective. Therefore, while a model might be good, if homes are unnecessarily destroyed, the model isn’t good enough. We’re developing wildfire modeling so it’s a standard, scientifically peer-reviewed model, which will prevent the loss of structures, homes and land. This model is mutually beneficial for both homeowners and insurance companies — and insurance companies would likely see an obvious and significant ROI increase from adopting it.

Case Study: Canyon 2 Fire in Anaheim Hills, California. October 9, 2017 – October 17, 2017

The first image shows what the model predicted the fire would do in 24 hours without suppression efforts as a factor. The second image shows the official fire perimeter a full week’s worth of active suppression efforts by both aircraft and hundreds of firefighters. In comparing the model against the final perimeter, you can see that fire suppression efforts were successful in stopping the fire at the eastern ridge line and along Highway 241. The difference is that the model predicted this wildland fuel area to have larger, rapid spread. The model did correctly predict the fire to jump Highway 241 and continue to burn aggressively to the south and west. Having our model results early in this incident could have helped decision makers visualize risk, prioritize response, and aid in evacuations due to the nature of the event.  All in all, the Canyon 2 Fire destroyed 25 homes and burned over 9,000 acres.

Canyon 2 Wildfire Model – first 24 hours of fire progression showing the fire’s extent without suppression

canyon2 final perimeter

Canyon 2 Final Fire Perimeter – shows the fire’s full progression with successful suppression efforts keeping it smaller than it could have been

 


Editor’s Note: This article was originally published in May 2017 and was updated in November 2017

Napa Sonoma Fires

Takeaways from the Napa Sonoma Fire Siege

Earlier this week I published some thoughts about the first 24 hours of the October Napa Sonoma Fire Siege. The unprecedented destruction caused by these fires provoked many questions in the emergency world, insurance, and especially the public. We asked our Senior Fire Liaison Doug Lannon his  thoughts to questions regarding;  1) Why were so many homes lost, 2) Why are these fires different, and 3) Why did we see so many homes burn to the ground, but some trees next to homes are still standing?

Weather

Northern California and the North Bay had been in Red Flag Warning conditions for several consecutive weeks before the fires, and were still under a Red Flag Warning when the fires began.  A severe “Santa Ana” type Foehn wind event coupled with low Relative Humidity and dangerously low fuel moistures were a design for disaster under the circumstances.

  • The winds were coming out of the northeast sustained at 40 mph with gusts up to 75 mph
  • Relative Humidity was in the single digits (RH below 20%, more receptive to ignitions)
  • Hot 80 and 90 degree temperatures contributed to the fuel ignition temperature and fire spread
  • During the autumn months, the North Bay temperatures are cooler and many people leave their windows open, making their homes and businesses even susceptible to ember intrusion

Fuels

Following more than five years of drought, the area received almost three times the normal amount of rain last winter and spring, causing two to three times the amount of grass crop and light flashy fuels to grow, but not enough to raise the living fuel moistures in heavy brush and timber to recover completely.  Also tree mortality is at an all-time high in the North State.

  • Dead fuel moisture sticks were hovering between 1 and 2 (10 is maximum, below 5 is serious)
  • Living fuel moisture was at 57% (80% is serious and below 60% is critical), 240% is maximum
  • Light and flashy fuels were abundant and twice as tall and thick as in normal years
  • Moderate to heavy fuels (brush and oak woodland) were extremely dry and abundant
  • Some homes did not have adequate clearance of native vegetation around the structures
  • Many homes had good clearance from native vegetation, but were surrounded by combustible ornamental shrubbery which also contributed to the fire spread into structures
  • Predominate fuel was grass, brush, and oak woodland which can send heavy embers skyward
  • Oak trees, palm trees, and conifer trees will send burning material high up into the convection column and those hot embers can rain down causing new spot fires ahead of the main fire
  • During the autumn months, oak leaves fall off trees adding to the combustible ground litter which can contribute to ember storms (similar to last year’s Gatlinburg Fires)
  • In some cases, ornamental shrubbery planted around homes appeared to have been well irrigated, causing some plants and trees to survive while homes burned

Topography

The areas where the fires were burning are mountainous, fairly hilly and in some cases steep and rugged.  Most drainages on the west side of the mountain ranges in the area are in perfect alignment for a northeast wind to send the fires down into the valley areas to the southwest and into populated, urban, and commercial areas.  Many homes were built along ridgetops and in canyons and passes adjacent to heavily wooded areas.

santa rosa neighborhood damage from the Napa Sonoma Fire Siege

Digital Globe Imagery released October 14th, 2017 shows whole neighborhoods wiped out in northeast Santa Rosa by the Tubbs Fire.

National Fire Danger Rating System

NFDRS components were at the extreme and very critical levels with the Energy Release Components (ERCs) at the highest levels we have seen in the past 26 years (since ERCs have been monitored).  The ERCs for these fires were greater than 90%.  ERCs relate to the available energy (BTUs) per unit area (square foot) within the flaming front at the head of a fire.  Daily variations in ERCs are due to changes in moisture content of the various fuels present, both live and dead.  So this number represents the potential heat release per unit area in the flaming zone.  As live fuels cure and dead fuels dry, the ERC values get higher, providing a good reflection of drought conditions.  Ignition Components (IC) were hovering between 90% and 100%.  The IC numbers represent an estimate of the probability of ignition when embers are blown in the wind ahead of the main fire and are able to contact a receptive fuel bed, then each could result in a new fire.  An IC of 90% to 100% means that if 100 embers are blown in the wind and come in contact with a receptive fuel bed, than those embers will result in 90 to 100 new starts (spot fires).  Scientific research is showing that many of the above factors can be attributed to Climate Change or Global Warming.

Multiple Fires and Lack of Available Resources

Multiple fires ignited during an extreme wind event, resulting in fifteen major fires burning at one time in Napa, Sonoma, Mendocino, and Solano Counties.  This quickly overwhelmed local, State, and Federal firefighting resources that would normally be available to respond mutual aid to the area where the fires were burning.  The first fire (Tubbs) along Tubbs Lane near Calistoga was ignited at about 2230 hours on Sunday night and began burning rapidly to the southwest towards Santa Rosa.  As more fires ignited, many resources that were originally responding to the Tubbs Fire were diverted to other new fires.  This trend continued for almost twelve hours, resulting in insufficient resources being assigned to active fires burning in the North Bay, while other in-state and out-of-state resources began responding for mutual aid, but had long travel times.  At the same time, other major fires were igniting, one in Orange County and two in Butte County, further taxing the State’s Master Mutual Aid system.  The causes for these fires are still under investigation and have not been released, but rumor has it that downed powerlines, downed power poles, and downed trees into powerlines were largely responsible for causing several of the fires.

Ember Storms

Abundant light, flashy, heavy, and ground litter fuels (dead leaves off of trees, etc.) coupled with the very high winds began blowing burning embers into receptive fuel beds.  This phenomenon was definitely a major contributor to the rapid fire spread, creating spotting.  Many homes and commercial structures had combustible materials next to and in close proximity to the structures, allowing the many spot fires created by embers to spread into those structures.

Rapid Evacuations

The majority of the fires were ignited at nighttime or in the early morning hours, catching people asleep and in their beds.  In many cases the fires were rapidly encroaching on structures when people were awakened and made aware of the hazard, causing many people to evacuate with only the clothes they were wearing and without closing some doors, windows, garage doors, etc.  This left homes more susceptible to ember intrusion, causing some homes to burn from the inside out.

destructive fires list showing four additions from the Napa Sonoma Fire Siege

An updated (Nov 1, 2017) look at California’s 20 most destructive wildfires with four fires added (in red) from last month’s Napa Sonoma fire siege.

 

Written by: Douglas J. Lannon, Senior Fire Liaison, RedZone Disaster Intelligence, LLC.