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The Chandler Burning Index (CBI) is a fire danger severity value that is calculated from the air temperature and the relative humididty. This numerical value is then indexed to relative severity adjectives. The input values for this calculation are taken from the local weather conditions every five minutes (there is no adjustment for fuel moisture) and these can and do change throughout the day. The current CBI presented here differs from that of the National Weather Service which computes a 30-day Chandler Burning Index based on forecasted weather conditions for the month. The formula for the CBI is as follows:


CBI = (((110 - 1.373*RH) - 0.54 * (10.20 - T)) * (124 * 10**(-0.0142*RH)))/60

where:

RH = Current relative humidity (percent)
T = Current temperature (degrees Celsius)

The continuous calculation of the CBI throughout the day permits graphical tracking of the diurnal CBI changes and enables an extrapolation of its trend for the remainder of the day. This is important for forecasting the progress of any fires in the Thomas Creek area. A graph showing the CBI for the last 24 hours can be seen by clicking on the fire danger dial graph. The 24-hr CBI graph is unique to this web site.











Chandler Burning Index for the Thomas Creek Estates neighborhood
Fire Danger Rating and Color Code Description
Low (Green) <50 Fuels do not ignite readily from small firebrands although a more intense heat source, such as lightning, may start fires in duff or punky wood. Fires in open cured grasslands may burn freely a few hours after rain, but woods fires spread slowly by creeping or smoldering, and burn in irregular fingers. There is little danger of spotting.
Moderate (Blue) 50-75 Fires can start from most accidental causes but, with the exception of lightning fires in some areas, the number of starts is generally low. Fires in open cured grasslands will burn briskly and spread rapidly on windy days. Timber fires spread slowly to moderately fast. The average fire is of moderate intensity, although heavy concentrations of fuel, especially draped fuel, may burn hot. Short-distance spotting may occur, but is not persistent. Fires are not likely to become serious and control is relatively easy.
High (Yellow) 75-90 All fine dead fuels ignite readily and fires start easily from most causes. Unattended brush and campfires are likely to escape. Fires spread rapidly and short-distance spotting is common. High-intensity burning may develop on slopes or in concentrations of fine fuels. Fires may become serious and their control difficult unless they are attacked successfully while small.
Very High (Orange) 90-97.5 Fires start easily from all causes and, immediately after ignition, spread rapidly and increase quickly in intensity. Spot fires are a constant danger. Fires burning in light fuels may quickly develop high intensity characteristics such as long-distance spotting and fire whirlwinds when they burn into heavier fuels.
Extreme (Red) +97.5 Fires start quickly, spread furiously, and burn intensely. All fires are potentially serious. Development into high intensity burning will usually be faster and occur from smaller fires than in the very high fire danger class. Direct attack is rarely possible and may be dangerous except immediately after ignition. Fires that develop headway in heavy slash or in conifer stands may be unmanageable while the extreme burning condition lasts. Under these conditions the only effective and safe control action is on the flanks until the weather changes or the fuel supply lessens.

Disclaimer:
Never make important decisions based on this or any weather information obtained from the Internet.

Note that the Chandler Burning Index does not take winds into account. The index only calculates relative fire danger in the absence of winds; therefore, high winds can override the above burn descriptions. Once the winds abate then the Burning Index will increasingly govern the burn. The Chandler Burning Index calculated by this website correctly predicted that the Washoe Drive and Caughlin fires would lay down hours before the local TV stations predicted it in 2011-2012. The reason for these successful predictions is that the weather data collected by the TCE station more closely matched that at those foothill fires than any weather data collected at the airport.