Update on Lower North Fork fire in Colorado

Lower North Fork Fire
Lower North Fork Fire. Credit: Jefferson County Sheriff's Office

(We will update this throughout the day on March 28 as developments occur.)

UPDATE at 12:30 p.m. MT, March 28, 2012

The reported size of the fire has been changed from 4,500 to 3,790 acres. This latest size was calculated from an infrared mapping flight that occurred at 10:30 p.m. on March 27.

The Jefferson County Sheriff’s office has reduced the number of damaged structures from 28 to 27. One of the recorded addresses was not accurate.

We have an audio recording of radio traffic from an incident that occurred on March 26 on the fire when four Jefferson County Sheriff officers were entrapped in the fire. They escaped unhurt, but the audio is gripping.

The Denver Post has some fascinating video that was shot by residents driving out of the fire. They said they did not receive a reverse 911 phone call warning.


UPDATE at 9:23 a.m. March 28, 2012

The Jefferson County Sheriff’s Office has updated their map of the fire with data from 8:20 p.m., March 27. The fire perimeter in red. The blue line is the evacuation area as of 2:00 p.m. on March 27. We expect they will give us an updated acreage later.

Map Lower North Fork Fire 2030 3-27-2012
Map Lower North Fork Fire 8:30 p.m., 3-27-2012. Jefferson County Sheriff's Office


UPDATE at 8:45 a.m. March 28, 2012:

The Jefferson County Sheriff’s Office released some updated information at 8:30 a.m. on Wednesday:

Overnight the fire was relatively stable. Fire crews made progress through the night in protecting structures. Today’s strategy is to gain containment around the fire while continuing to protect structures.

Today’s fire behavior is expected to be similar to yesterday but with slightly higher winds. The winds could result in more robust fire activity. The fire will also most likely become more intense as the temperature rises throughout the day. The fire has continued to exhibit a tendency to start spot fires in a wide area.


The Jefferson County Sheriff’s Office will continue to man road blocks around the fire perimeter. At this time we are not allowing anyone back into the evacuated regions.

The Sheriff’s Office said the estimated size is still 4,500 acres and that 28 structures have been damaged.


(Original  post at 7:30 a.m. MT, March 28.)

The Lower North Fork fire that is southwest of Denver and seven miles southeast of Conifer, Colorado, was relatively quiet during the night. The last official acreage that was released by the Jefferson County Sheriff’s Office for the wildfire was 4,500, and they reported that 23 homes have been damaged. An elderly couple was found dead near their home and one resident within the burn area is missing.

The map of the fire shows the fire perimeter in red, as of 11:00 p.m. on March 26. The blue line is the evacuation area as of 2:00 p.m. on March 27. We will provide an updated map as more information is provided.

Map Lower North Fork Fire 732 am 3-28-2012
Map Lower North Fork Fire. Jefferson County Sheriff's Office

The firefighters’ strategy on Wednesday is to switch from point protection to constructing fireline to begin containment of the fire. They had hoped to do that on Tuesday, but the weather and fire behavior did not cooperate, pushing them back into a defensive and structure protection mode. Containment is still listed at zero percent, and 900 homes are still under a mandatory evacuation order. On Wednesday three air tankers (two P2Vs and one single engine air tanker) and four helicopters (including two National Guard Blackhawks) will be working on the fire. More aircraft are on order.

The Rocky Mountain Area Coordination Center reported Wednesday morning that Rich Harvey’s Type 1 Incident Management Team arrived and in-briefed at 8:00 p.m. on Tuesday and will assume command at end of the shift today. The RMACC says 3,790 acres have burned. This reduction in size is probably due to more accurate mapping as a result of the aircraft that Tuesday night used infrared equipment to determine the fire perimeter.

On Tuesday the Colorado State Forest Service released a statement saying a prescribed fire they ignited on Wednesday, March 21, escaped control on Monday, and investigations are underway to determine the cause of the Lower North Fork fire. The Denver Post earlier on Tuesday quoted Jacki Kelley, a Jefferson County Sheriff’s Office spokeswoman, as saying the fire originated from a controlled burn conducted by the Colorado Forest Service.

This first video is from a 6:00 a.m. newscast on March 27.

The video below is from March 26.

9news.com occasionally has live video reports about the fire.

Read Wildfire Today’s March 27 coverage of the Lower North Fork fire. and the March 29 article.

Colorado fire update: 2 fatalities; 16 structures burn; fire map

Map Lower North Fork Fire 0900 3-27-2012
Map showing heat on the Lower North Fork Fire detected by satellites, March 27, 2012

(Read our March 28 update on the Lower North Fork fire and our March 29 update.)

UPDATE at 5:00 p.m. MT, 3-27-2012

The Jefferson County Sheriff’s Office has provided additional information about the Lower North Fork Fire:

  • 23 homes have been damaged by the fire.
  • 4,500 acres have burned
  • Two air tankers are working the fire: a single engine air tanker and a large P2V. Two military helicopters are also assigned.
  • Increased fire activity today convinced the incident management team to issue a pre-evacuation notice to an additional 6,500 homes north and east of the fire.
  • 200 firefighters are on scene.
  • Containment is at 0%. Due to the fire behavior, firefighters had to back off from their aggressive strategy this morning, to more of a defensive strategy emphasizing structure protection.
  • The Type 1 Incident Management Team has arrived. There is no word yet on when they will assume command. Our best guess at Wildfire Today is sometime on Wednesday.


UPDATE at 3:25 p.m. MT, 3-27-2012:

The Jefferson County Coroner’s Office has identifed the two fatalities from the Lower North Fork Fire as a husband and wife, Samuel Lucas, 77, and Linda Lucas, 76.

Air Tanker 44 drop 312 pm 3-27-2012
Air Tanker 44 dropping at 3:12 pm 3-27-2012, on the Lower North Fork Fire. 9News

UPDATE AT 2:24 p.m., March 27, 2012

The Jefferson County Sheriff’s Department has updated the map of the Lower North Fork fire. The blue line is the evacuation Area as of 3/27/2012 at 2:00 p.m. This evacuation zone is the original area and does not include the pre-evacuation notice to 6,500 homes located in regions north of the existing evacuation area. The additional pre-evacuation notice was sent out because “current weather conditions have caused the fire to act in an erratic manner which may threaten those 6500 homes”.

Map Lower North Fork Fire 220 pm 3-27-2012
Map, Lower North Fork Fire, updated at 2:20 p.m. 3-27-2012. By Jefferson County Sheriffs Office


UPDATE at 12:33 p.m. MT, March 27, 2012

As the temperature rises and the humidity decreases, activity on the fire is picking up. At least two air tankers are actively dropping retardant on the fire, a Single Engine Air Tanker, and Tanker 44, the P2V which is the tanker than ran off the end of the runway at Rocky Mountain Metro Airport in 2010 after its brakes failed. The aircraft was repaired at the airport and has been stationed there for the last week or so. Two National Guard helicopters are enroute from Buckley Air Force Base to start dropping water.

Lower North Fork fire, 4:00 p.m, 3-26-2012
Lower North Fork fire, 4:00 p.m, 3-26-2012. Photo provided by Jefferson County Sheriffs Office
Tanker 44 drop 1231 pm 3-27-2012
Tanker 44 dropping on the Lower North Fork Fire at 12:31 p.m., 3-27-2012. Credit: 9News

Continue reading “Colorado fire update: 2 fatalities; 16 structures burn; fire map”

Monday wildfire one-liners, March 26, 2012

Screen grab from report about Colorado wildfire conditions
Screen grab from CBS Denver report about Colorado wildfire conditions

Excellent photos of a P2V and an Air Tractor 802A at Jeffco Air Tanker Base in Colorado.

Annual wildfire refresher available, online and by DVD. Warning: a lame, pointless video with audio will automatically play for about 15 seconds when you visit the NIFC web site.

Video report about wildfire conditions in Colorado.

U.S. Forest Service starts women’s firefighting boot camp.

Two boys ordered to pay $10,000 each for starting fire near Gardnerville, NV.

New Hampshire man uses gasoline to ignite brush pile, is treated at hospital for burns on hands and face.

Two Single Engine Air Tankers begin their 7-day journey from Australia to the United States.

Meteorologist gives early prediction of a normal fire season for the northern Rockies.

One home and two outbuildings burn in three-acre wildfire in Chimayo, NM.

During the past 10 years, the Alabama Forestry Commission’s staff has been reduced by more than 300 employees.

Documentary about Fourmile Canyon fire

I wish I had known about it earlier, but last night Colorado Public Television aired a documentary about the Fourmile Canyon fire that burned 6,200 acres and destroyed 168 homes west of Boulder, Colorado on Labor Day in 2010. The documentary tells the story of seven residents who refused to evacuate but fought the fire on their own.

Here is the trailer for the program.

Did anyone see it Tuesday night?

More information about the program.

Articles on Wildfire Today about the Fourmile Canyon fire.

Report released on Colorado’s Fourmile Canyon fire

A draft report has been released about the the Fourmile Canyon fire. The fire started on September 6 and burned 6,200 acres and 168 homes a few miles west of Boulder, Colorado. The fire was devastating to local fire districts within the burned perimeter in several ways, including the facts that a firefighter’s burn pile escaped and started the fire, the homes of 12 firefighters burned, and one fire station and an engine inside it burned. Wildfire Today covered the fire extensively.

Fourmile fire_map_MODIS_0418_9-8-2010
Map of the Fourmile fire near Boulder, showing heat detected by the MODIS satellite at 4:18 a.m. Sept. 8.

One of the interesting findings was that some fuel treatments done before the fire came through actually increased the intensity of the fire, compared with untreated areas. This was primarily due to the more open stands allowing wind to push the surface fires, and the treatment prescriptions’ emphasis on thinning to a target basal area (density of trees) rather than designing a prescription that accounted for fire behavior during dry and windy conditions. In addition, a significant amount of surface fuels remained, including slash piles in some areas that had not been burned after the treatments.

Another finding was that 83% of the homes that burned were ignited by surface fire, rather than a crown fire, which is typical.

The report includes some statistics on the use of aircraft on the fire. I broke out a calculator and did some analysis, arriving at these numbers:

  • $343,082, total cost of the retardant dropped by air tankers (just the retardant).
  • $1.97, cost per gallon of retardant (just the retardant).
  • 174,149, gallons of retardant dropped by air tankers.
  • 86, loads of retardant dropped by air tankers.
  • 47.09, total flight hours by air tankers.
  • 3,698, gallons of retardant dropped per flight hour by air tankers.
  • $3.55, total cost per gallon for the delivery of retardant by air tankers.
  • $619,483, Total cost of the air tankers, including retardant and flight costs.
  • 0.55 hour, the average time for each air tanker drop. (This is extremely low and is due to the fact that the air tankers were reloading at Rocky Mountain Metropolitan Airport near Boulder, Jeffco air tanker base, about 15 air miles from the fire. This helped keep the cost per gallon of delivered retardant lower than on your typical fire, which is normally much more than 15 miles away from the reload base.)

As a comparison, on September 9 there were three large Type 1 helicopters dropping water:

  • $99,284, Total cost for the three Type 1 helicopters on September 9.
  • 71,950, gallons of water dropped by the three helicopters.
  • 12.9, hours flown by the three helicopters.
  • 5,577, gallons of water dropped per flight hour by three Type 1 helicopters on September 9.
  • $1.38, cost per gallon of water delivered.
  • (?) the number of loads of water delivered was not specified.

A decision about using helicopters vs. air tankers should be based on more than just the above numbers. Retardant, sometimes known as “long-term retardant”, slows the spread of a fire more effectively and for a longer period of time than plain water. And helicopters cruise at a much slower speed than an air tanker, so depending on their location at the time of initial dispatch, it can take much longer to arrive at the fire.

Scroll down to see a map showing the location of every drop by a large air tanker on the fire.

Moving on to the rest of the report, here are some excerpts:


Fuel Treatments

  • Thinning trees to a specified density (residual basal area) or spacing was the prescription often negotiated with land owners. In addition, the treatments were often focused on improving the health of the forest (removing diseased and malformed trees, i.e., dwarf mistletoe) rather than modifying fire behavior.
  • Pervasive spotting observed during the Fourmile Canyon Fire easily breached the narrow fuel treatment units and rendered them of limited value to containment efforts.
  • The abundance of grasses, forbs, shrubs, and often branches and twigs that could have been removed through judicious surface treatments (e.g., prescribed fire) occurring within the areas where the fuels had been treated contributed to the high fire intensities and fire spread rate observed.
  • Post-fire satellite imagery clearly shows the absence of changes in stand condition inside treated areas compared to neighboring untreated stands. In some cases, treated stands appeared to burn more intensely than adjacent untreated stands, perhaps because of additional surface fuels present as a result of the thinning. One clear example of this comes from near Gold Hill where the piles of slash were scattered in the understory of a thinned stand but had not been burned.

Smoke from Fourmile fire provides bonanza for researchers, bad news for firefighters and the public

smoke in Moscow
A woman wears a mask in central Moscow to "protect" herself from smoke from fires outside the city. August, 2010. Photograph: Mikhail Voskresensky/Reuters

When the Fourmile Canyon fire was burning west of Boulder, Colorado in September, 2010, Jim Roberts, a chemist with NOAA’s Earth System Research Laboratory, was surrounded by something he had previously studied at the U.S. Forest Service’s Missoula Fire Science Laboratory in Montana — smoke, and lots of it. In Missoula he used a new instrument they had built, a custom mass spectrometer, to examine the levels of isocyanic acid in the atmosphere and in smoke. Isocyanic acid has been difficult to detect with conventional measurement techniques. At Missoula, he measured the levels of the chemical in smoke generated when the researchers burned vegetation in the lab and in cigarette smoke.

When the Fourmile Canyon fire started, Roberts had the mass spectrometer at the University of Colorado at Boulder’s Cooperative Institute for Research in Environmental Sciences.

Here is an excerpt from the Daily Camera:

Isocyanic acid easily dissolves in water, which makes it possible for the acid to also dissolve into moist tissues in the body, including the lungs. The full health effects of exposure to isocyanic acid in the air aren’t fully understood, but the chemical has been linked to cataracts, cardiovascular disease and rheumatoid arthritis.

Last September, the researchers had the opportunity to measure the presence of the acid in a real wildfire. On Labor Day, the Fourmile Fire began burning in the foothills west of Boulder, just a few miles upwind of the state-of-the-art atmospheric instruments housed at NOAA’s campus on Broadway.

“Boulder has a world-class atmospheric chemistry building and only once in its lifetime is it going to have a full-on hit from a wildfire,” said Joost de Gouw, a co-author of the study and a researcher at the Cooperative Institute for Research in the Environmental Science. “So just everyone in that building turned on their instruments.”

CIRES is a joint institute of the University of Colorado and NOAA.

The sensitive new spectrometer used in Missoula also picked up the isocyanic acid in the plume of smoke from the Fourmile Fire.

More information

Fourmile fire near Boulder
Smoke from the Fourmile fire as imaged by the MODIS satellite on September 6, 2010.