FIRE WEATHER

During forest fire season, weather is the controlling factor in the severity and frequency of fires. Dry, hot weather rapidly increases the danger of wildfires. In cool, damp weather there are fewer fires, and when one starts it can be brought under control more easily.

Up-to-date weather forecasts and information on the fuel and weather conditions in the forest are crucial for effective decision making in all aspects of fire management.

Weather Stations

The Ministry of Forests Protection Program operates 214 hourly weather stations.

The B.C. Fire Weather Network records hourly weather observations which are used to support fire weather forecasting and the Canadian Forest Fire Danger Rating System (CFFDRS).

The computer-based CFFDRS, developed by the Canadian Forest Service, is the primary fire management decision aid in Canada. With it, fire managers can assess the potential for wildfire ignition, spread and burning intensity. This information is used for making fire prevention, preparedness and suppression decisions, as well as other general fire management decisions.

Temperature, relative humidity, precipitation, wind speed and wind direction are recorded hourly by the fully automated fire weather stations. This data is transmitted to Protection headquarters, every hour from April through October and less frequently during the winter months. Various calculations are performed with this data to arive at six Fire Weather Indices. No field maintenance is performed over the winter, so sites that shut down will usually remain inoperative until the pre-season service has been completed.

Data from suitable Environment Canada stations is also utilized to supplement information collected by the Fire Weather Network. The Environment Canada data, consisting of noon Pacific Standard Time readings of temperature, relative humidity, wind speed and direction and accumulated precipitation for the previous 24 hours, is transferred electronically once a day to Protection headquarters.

All data from the hourly stations is archived electronically. In addition, stored data is also available from numerous temporary sites that have been in operation for varying periods of time throughout B.C.

FORECASTING

During fire season, the Ministry of Forests Protection Program employs one weather forecaster for each of the six fire centres.

The forecasters issue general fire weather forecasts for the fire centres once or twice daily depending on the severity of the conditions. They also provide point forecasts for 3 days ahead for each key weather station in their jurisdiction. Upon request, the forecasters issue spot forecasts for specific sites and purposes (i.e. project fires, prescribed fires, etc.).

Lightning Locators

Lightning is one of the major causes of wildfires. On average, about 50 percent of all forest fires in B.C. are caused by lightning. These lightning-caused fires cost millions of dollars to extinguish and can destroy timber, cut forest products, equipment and structures, but are also a natural part of the ecosystem.

The Canadian Lightning Detection Network, provided by Environment Canada, consists of a network of lightning locators that provide complete coverage of the province. The Protection Program pays an annual fee for real-time access to the data. This network can detect more than 90% of all lightning strikes occurring in B.C. Each lightning locator consists of antennas, and an analogue and digital microcomputer to detect the electromagnetic radiation generated by a lightning strike.

To collect the data, the lightning locators continuously detect and record all cloud-to-ground lightning strikes as they occur within or near British Columbia. Lightning data is triangulated and the approximate location of the lightning strike is determined. After triangulation, the data is sent to a large main-frame computer. All of this takes about 60 milliseconds. The information is then sent to Protection.

Once received by the assigned server at Protection headquarters, the latitude and longitude, time and polarity of the strike is moved into a database and is available for plotting on computer-generated maps. Forest Service personnel can create maps that show the location, day, and time for any lightning strike. Forest Service personnel can then check lightning hot spots for new wildfires. Information from this system is also used by fire managers to route and schedule air patrols and to determine standby and resource allocation.

Lightning can strike almost anywhere, even as far as 15 kilometres away from a storm cell, so may not be affected by rain. Dry lightning can also occur under the storm cell when the base of the cloud is so high that the rain evaporates before reaching the ground. Dry lightning is a potent ignition source because if the fuels are dry there will not be enough moisture to interfere with ignition or fire spread.

Personal Lightning Safety Tips

AVOID: Avoid water. Avoid all metallic objects. Avoid the high ground. Avoid solitary tall trees. Avoid close contact with others.

SEEK: Seek clumps of shrubs or trees of uniform height. Seek ditches, trenches or the low ground. Seek a low, crouching position with feet together with hands on ears to minimize acoustic shock from thunder. If you can, you should seek shelter. If you are in a car, be sure that the windows are rolled up.

KEEP: Keep a high level of safety awareness for thirty minutes after the last observed lightning or thunder.