A large area of the central and north-central U.S. is under a wildfire Red Flag warning for Tuesday, March 13. Forecasters predict warmer than normal temperatures, low relative humidities, and gusty winds. Areas in the following states are included: Montana, North Dakota, Wyoming, South Dakota, Nebraska, Colorado and Kansas.
More information
UPDATE at 10:32 am MT, March 13, 2012:
While part of Wyoming is under a red flag warning, another area of the state is affected by a winter weather advisory. The National Weather Service said, at 2:39 am on Tuesday, that 6 to 12 inches of snow are possible in Yellowstone National Park:
Moist southwest flow will bring significant snowfall to the mountains of northwest Wyoming this afternoon through early afternoon Wednesday. Moderate to heavy snow is possible in the northwest mountains of Wyoming….
The Predictive Services section at the National Interagency Fire Center has issued their National Wildland Significant Fire Potential Outlook for March through June, 2012. The eastern United States should experience temperatures much above normal in March, and drought conditions are predicted for the southwest, the southeast, and Minnesota through May.
Below is a summary of the wildfire potential:
Above Normal Significant Fire Potential is expected along the east coast from near Wilmington, North Carolina, to near Panama City, Florida, including all of the Florida peninsula; most of northwestern Nevada; foothills and inland valleys of southern California; and the lee side of the Hawai’in Islands.
Significant Fire Potential will increase to above normal in the spring across most of Minnesota, northern Wisconsin, the upper peninsula of Michigan and northwestern Iowa; central and western New Mexico, most of Arizona, southern Nevada, far southern Utah and extreme southwestern Colorado.
Below Normal Significant Fire Potential is expected for much of the Ohio and Tennessee Valleys, the middle and lower Mississippi Valley, and Puerto Rico.
The rest of the country will have normal significant fire potential.
Southwest Coordination Center meteorologist Chuck Maxwell told the Albuquerque Journal that due to the drought there has been no additional grass growth in the last two years and that he expects the eastern portion of the state to see 25 percent of the fire activity it saw last year.
The public, and sometimes firefighters, become confused with proclamations about how precipitation or the lack of it will affect wildfire activity, sometimes with the same result. Often you hear that more rain than normal will produce above normal grass growth, adding fuel for potential fires which will increase the rate of spread and the opportunity for ignitions. On the other hand, a drought can reduce the fuel moisture in both live and dead vegetation which can increase the rate of spread, the spotting potential, the intensity, and the resistance to control of wildfires.
It is a complex equation, balancing past and predicted precipitation along with the amount and condition of the fuel. And of course the weather DURING the fire season can have more effect than the weather before the season and the fuel characteristics. Theoretically, the folks at the National Interagency Fire Center take all of this into account when they issue their monthly outlooks, like the one below from February 1, 2012.
The Kisatchie National Forest near Alexandria, Louisiana (map) has plans to burn 130,000 acres in prescribed fires this year, according to Ed Bratcher, the U.S. Forest Service Fire, Land and Mineral Team leader. Much of the ignition will be done with a helicopter. Here is a link to a recent video in which Larry Kyle said they were about to ignite a 1,155-acre prescribed fire with 14 firefighters, including those in the helicopter. He expected they could get it done in four to five hours.
Extremely dry in some regions of the United States
I stopped trying to predict the intensity of fire seasons long ago. The number of fires and acres burned is primarily affected by the weather DURING the fire season. If the fire season is cool and wet, there will not be many large fires. But if the current trends continue for several months, the extremely dry conditions in some areas of the United States could lead to firefighters being very busy.
The “Percent of Normal Precipitation” map indicates that those areas include the upper midwest, the southwest and the southeast. As the east coast and midwest enter their fire seasons, firefighters could find themselves going from fire to fire.
The CBS station in Minneapolis, Minnesota quotes Byron Paulson, the Fire Weather Program Leader at the National Weather Service, as saying he’s never seen the land as dry as it is this year.
Below is one of the maps from our article on February 1 which covered the wildfire potential for the next 30 to 90 days.
The Predictive Services section at the National Interagency Fire Center has issued their National Wildland Significant Fire Potential Outlook for February through May, 2012. According to their prediction, several areas of the United States will have above normal wildfire potential during this period.
La Niña: La Niña remains at near moderate strength and is expected to slowly weaken during the spring months. Classic weather patterns of wet and cold in the northwest and warm and dry in the south are expected, although intensity of these cannot be directly correlated to the strength of La Niña.
Drought: Significantly above normal precipitation fell January across parts of West and North Texas and southern Oklahoma. The Northwest also received significant precipitation. However, large parts of the Southwest and the Plains states remained much below normal. Severe to exceptional drought continues across the south central and far southeastern parts of the U.S. and over parts of the upper Mississippi valley.
Fuel Dryness: Late January and early February have brought a transition to much of the U.S. The southern tier continues to see drier than normal conditions, except across some portions of Texas, where precipitation is moistening fuels even though drought conditions remain prevalent. Also, tree mortality from drought will continue to be problematic. Across much of the west, including the Great Basin fine fuels remain heavy and continuous and are largely dry or capable of quickly drying. Significant fires will be possible with the combination of ignitions and windy conditions. The formerly dry Northwestern quarter of the country has begun to see significant moistening and snowpacks are beginning to increase. In the east the northern tier will largely be near normal seasonal fuel conditions with some dryness lingering across the Great Lakes states. The southeast will continue drier than normal fuels conditions south and east of the Tennessee Valley.
The rapid escalation of a small fire due to fire channelling can result in a catastrophic decay in both firefighter and community safety that is counterintuitive.
That is how the authors of a paper wrapped up their findings about a weather phenomenon that can cause a wildfire to spread in unexpected directions. “Fire channelling” can force a fire on the lee side of a ridge to spread 90-degrees from the general wind direction. For example, if a west wind pushes a fire across a north-south ridge, on the lee or east side of the ridge the fire could spread to both the north and the south, counterintuitively.
The white arrow shows the general wind direction. The black area was not imaged by the line-scanner on this run. From the Sharples, McRae, and Wilkes paper funded by the Australian government.
Generally a strong wind has the most effect on the direction of spread of a fire — more so than topography or fuel. If a fire is spreading with a strong west wind, the rate of spread on the flanks, the north and south sides, will be much less than the head of the fire on the east side. Unless — fire channelling is occurring.
Firefighters usually face less risk when they attack a fire on the heel or flanks of a fire. In most cases it can be impossible to safely attack the head of a fast-moving fire in heavy fuels. But this fire channelling phenomenon has the potential to present firefighters with unexpected fire behavior, putting them in a dangerous situation on what they expected to be the flanks of a fire that suddenly converted to heads of the fire.
Fire channelling caused by wind-terrain-fire interactions. From the Sharples, McRae, and Wilkes paper funded by the Australian govermnent.
The authors of the paper, which is titled Wind–terrain effects on the propagation of wildfires in rugged terrain: fire channelling, considered several causes of fire channelling, including thermally induced winds, pressure-driven channelling, forced channelling, and downward momentum transport, but they settled on wind–terrain–fire interactions as the most likely mechanism driving the atypical spread. Here is an excerpt providing some details about wind–terrain–fire interactions:
…If a fire happened to spread into a region affected by a separation eddy, then the hot gas from the fire could be entrained within the eddy, with the strong wind shear at the top of the eddy impeding mixing between the synoptic and separated flows. Hence, supposing a fire enters a region of separated flow at the north end of a slope or valley, and treating the air within the eddy as a quasi-isolated system (i.e. a system that involves only limited mixing with the surrounding environment; cf. Byron-Scott 1990), the air within the northern part of the eddy will be at a higher temperature and pressure than the air within the southern part of the eddy. As a consequence, the air within the eddy will tend to move towards the south in response to the thermally induced pressure gradient or simply owing to thermal expansion of the air within the eddy. Based on the available evidence, such an interaction constitutes the most likely mechanism driving the atypical spread.
Access to the research
If you want to read the paper you will have to pay CSIRO Publishing $25, in spite of the fact that the authors appear to be funded by the Australian government. It was written by Jason J. Sharples, Richard H. D. McRae, and Stephen R. Wilkes who are associated with three organizations in Australia, the University of New South Wales at the Australian Defence Force Academy, the Bushfire Cooperative Research Centre, and the ACT Emergency Services Agency.
This is another example of government funded research that taxpayers have to pay for twice. Once when the government-paid employees conduct the research and write the paper, and a second time if a person wants to read it. We have written about this lack of Open Access numerous times before. However, this example is a little murky, in that the government sponsored research was published by CSIRO, a governmental body. But many U.S. wildfire researchers who are government employees publish their papers in the same CSIRO publication, the International Journal of Wildland Fire, behind a pay wall.
Sign the petition
At the U.S. White House web site you can sign a petition to make government funded research available at no additional charge to the public. Let President Obama know that you oppose HR3699, the Research Works Act, which is an attempt to put federally funded scientific information behind pay-walls and confer the ownership of the information to a private entity. You will need to register at the site, giving them a name and a real email address.
A large area of the central and north-central U.S. is under a wildfire Red Flag warning for Tuesday, March 13. Forecasters predict warmer than normal temperatures, low relative humidities, and gusty winds. Areas in the following states are included: Montana, North Dakota, Wyoming, South Dakota, Nebraska, Colorado and Kansas.
