Because heat rises, fire generally burns uphill.
But strange things happen to fire on the east slope of the Sierra Nevada, according to Carson City Assistant Fire Chief and Fire Marshal Stacey Giomi.
"We get sort of an oddity here," he said. "Because of the down-slope winds, fire can move down a slope as fast or faster than it moves up."
A high-pressure system hanging over the Great Basin pulls cool air from the Pacific through California's central valleys to the Sierra range, where it spills over into Nevada.
"That's why there's almost always wind in the afternoon here," Giomi said.
With that in mind, consider the following fictional wildfire scenario based loosely on the fire which descended into Carson City's Old Clear Creek Road neighborhood last year.
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Heat waves shimmer above the asphalt as an eastbound diesel truck rolls over the crest of Spooner Summit at noon on a June day. The driver downshifts before descending into Carson City and the truck's muffler coughs up a spark.
It falls into the bone-dry pine needles blanketing the surrounding forest floor. Within minutes, the spark has blackened a handful of needles. Fanned by an increasing afternoon breeze, the smoldering hot spot jumps into life as a dancing orange flame.
The first 911 call reports a column of smoke seen in the Department of Transportation right of way.
A dispatcher at the Carson City Fire Department call center immediately alerts a crew from Station One.
Firefighters spring into action, starting trucks and donning gear on the road. Within a few minutes of the 911 call, two fire engines, a battalion chief in a command vehicle and a rescue unit (ambulance) are headed to the scene, lights flashing.
Meanwhile, the Carson City Fire Department's computer system is thinking. It is programmed to consider the outside temperature, recent precipitation, wind speed - even the number of structures near the reported fire. It recommends the dispatcher contact the Interagency Dispatch Center in Minden.
After the Minden center gets the call, its computer starts thinking. With more complicated programming and a screen the size of a door, the computer tracks factors such as lightning strikes and relative humidity to create a daily "Fire Danger Rating."
Based on that day's rating, the Minden center may immediately call in U.S. Forest Service fire crews and air tanker support.
Because the Carson crew was the first dispatched and the closest, they arrive first and set up a command post.
As cooperating agencies arrive, their chief officers find the command post based on details broadcast over the radio.
Firefighters jump from their engines and spray the growing blaze with water from tanks on the trucks. "Line troops," or ground crews, begin the hot, exhausting work of cutting fire breaks - wide swaths where all burnable materials are removed in order to stop the advancing fire.
As crews work to corral the fire, a team of leaders form a command structure with the incident commander at its head. They make decisions about what additional resources are needed.
As the east-blowing afternoon winds push the fire down toward the Old Clear Creek neighborhood, additional resources - more firefighters, trucks, equipment or air tankers - are called in.
They are drawn from the closest agencies first. Crews first come from the local department, then surrounding departments such as Douglas County or Incline Village. As the blaze continues to grow, fire crews from federal agencies placed around the region - the Bureau of Land Management and Nevada Division of Forestry - are also called in.
"At this point we're not concerned about who's fire it is, who owns the land, or who's jurisdiction it is," said Giomi. "Our concern is, we need to get this fire out."
As the threat of fire approaches the Clear Creek neighborhood, the Carson City Sheriff's Department will be called on. Deputies will be tasked with controlling traffic and helping with evacuations. If evacuation is deemed necessary, deputies and volunteers will move through the neighborhood with bullhorns to alert residents. Billows of smoke rush over the area, turning afternoon sunlight a dim orange.
Residents pack their belongings in cars, spray their properties with garden hoses, and rescue unattended dogs and horses.
Sharon Arnold, an Old Clear Creek resident, experienced last year's Highway 50 fire first-hand. "We saw it when it first started - I called it in but it had already been reported," she said.
"Once the fire got going we lost power and telephone, because all our power feeds come from that area. I think it burned three or four power poles down," she said.
As residents evacuate, the Sierra Nevada Chapter of the Red Cross will set up shelters with cots, blankets and first aid supplies - probably at the Carson City Community Center.
The command team is informed by dispatchers of spot fires (started by sparks blown in from the main fire) called in by residents.
Around this time, the command structure is considering whether they are fighting what's called a "campaign fire" (which could last for days or even weeks) or the kind of fire that will pretty much be out by the following morning.
If the fire continues to grow, dispatch centers with larger and larger circles of authority will be notified. The call will go from a regional center to the National Interagency Dispatch Center in Boise, Idaho.
"They have the ability to reach out for national resources," Giomi said. (During last year's extensive fires in Southern California, crews were called in from around the West).
If the fire continues to grow and looks like it will be a campaign fire, the incident commander will consider bringing in an on-call "Fire Management Team." Made up of acting fire chiefs from around the region, the 30-person team will work together to achieve tactical objectives in the battle against the blaze.
"These are the generals if you will, the colonels," Giomi said.
Contact Karl Horeis at email@example.com or 881-1219.