2012 ISSUE 3
In this Issue: Lightning Trails Duty to Report a Wildfire At Coastal
See detailed weather forecast page 2
JUNE 15, 2012
Thunderstorms, Lightning and Wildfire Thunderstorms develop in response to the dynamics of an unstable atmosphere. These storms can affect forest fires because of associated weather conditions such as rainfall, wind and lightning. Rainfall and the higher humidity that accompanies it are the principal benefits of thunderstorms. However, when the rain from thunderstorm cells evaporates before hitting the ground, it is called “virga” and results in “dry lightning”. Dry lightning causes many forest fires in B.C. each year. A dry thunderstorm is potentially more dangerous than a wet thunderstorm, because lightning that strikes the ground frequently starts fires in dry fuels like dead wood or brush. The storm’s downdraft and outflow winds usually reach the ground, even if precipitation does not. This combination of
burning dry fuel and strong, gusty winds can be disastrous. Although dry lightning is the most devastating form of lightning for starting forest fires, a thunderstorm doesn’t have to be dry to cause problems. A storm will often pass through a region without starting a fire because of the associated rain. However, if conditions are drier in the days following the storm, a “holdover fire” can occur. This is caused when a lightning strike starts an undetectable sub-surface fire that does not begin to burn on the surface until weather conditions allow it to do so. The 2009 fire season was one of the worst lightning seasons ever recorded in the Coastal Fire centre, with lightning fires outnumbering person-caused fires by 328 to 200.
Duty to Report a Wildfire
On September 4, 1918, the first airplane to patrol for forest fires in the province was commissioned from Hoffar Brothers of Vancouver by the British Columbia Forest Branch. The flying boat was designed by the Curtiss Aircraft Company and built for the price of $8,000. The maiden flight was piloted by Lieut. V.A. Bishop, a resident of Vancouver who was on leave from his duties as a flight instructor in England. Unfortunately, the plane plunged from a height of over 450 metres and crashed into a house in West Vancouver just half an hour into its first run. As a result, airplanes were not used to patrol for wildfires until 1920. - Research by
One of the most basic tenets of the Wildfire Act is the responsibility of citizens to report wildfires when they spot them. According to the act, “a person, other than a person acting in accordance with section 5(2) or 6(3), who sees an open fire that is burning in forest land or grass land or within 1 km of forest land or grass land and that appears to be burning unattended or uncontrolled must immediately report the fire: (a) to an official employed in the ministry, (b) to a peace officer, or (c) by calling a fire emergency response telephone number” The prompt reporting of a wildfire minimizes damage to the forest, costs to the public and potential injuries to firefighters. Being a proactive citizen is sometimes as easy as picking up the phone!
To Date in Coastal
Fires to Date Person Caused
Total Number of Fires
Hectares burnt Number of Incidents Responded to
Despite the unpredictability of thunderstorms, they do follow somewhat predictable patterns. They only occur in unstable air masses that allow upward air movement to produce cumulonimbus clouds. The air has to be moist enough to prevent dry air evaporating and dissipating the cloud. There also has to be one or more “lifting agents”, such as mountains, weather fronts and upper troughs. Thermodynamic thunderstorms are produced by features like daytime heating and high dew points. They are slow-moving or stationary and they typically develop in “favoured areas” that produce these conditions. They generally dissipate when the sun goes down. Dynamic thundershowers exhibit the same features but are generated by systems that “move”, like weather fronts and troughs. These storms can move quickly as they follow the weather system that created them. They can also produce hail, extreme winds and even tornadoes.
Most of British Columbia experiences weather that originates over the Pacific Ocean and migrates to our coast. As these systems hit the coast, they push winds along valleys and over mountains in a somewhat predictable way. All this activity creates “lightning alleys” in coastal areas. If low-pressure systems travel to the south of B.C., the counter-clockwise rotation of winds around them will direct winds to the east side of the Coast Mountains, and if other conditions are favourable, the Coastal Fire Centre may experience lighting in the Fraser Canyon and in the mountains near Pemberton. This instability can also travel from the mainland across the Salish Sea and produce lightning along the mountainous spine of Vancouver Island. If such a low-pressure system moves further north, it can produce lightning storms across the southern end of Vancouver Island and across the Lower Mainland as it passes from west to east. The Coastal Fire Centre is well aware of these coastal ”lightning alleys” and so it positions firefighting crews and resources appropriately when thunderstorms are predicted for the coast.
Today At Coastal
With the weather being cool our crews have the opportunity to continue with their training and certification. Project work also continues with crews learning new skills that will be applied later in the season.
SYNOPSIS.. A moderately strong upper ridge currently over southern Coastal zones will bring a mainly sunny warm day. But heavy clouds are approaching starting over Haida Gwaii this morning. There, rains will begin by noon, winds will increase to 30 to 50 kph in the afternoon, and freezing levels will rise to over 10,000 feet by evening as a major winter type storm crashes into the coast. The same weather will reach the Mid-coast about 6 to 10 hours later and there the forecast models suggest up to 100 mm of rain tonight over the outer coast islands and possibly 20 to 25 mm for Bella Coola. By noon Saturday rain has reached all Coastal zones with the heaviest falls likely continuing over the Mid-coast but also along outer Vancouver Island and down the Sunshine Coast as well. By late Saturday the rainfall is easing as the storm moves inland and loses strength but heavy local showers will continue especially on the coastal mountains western slopes. Flooding concerns will be amplified due to rising freezing levels. LONG TERM TREND.. After the major storm dies out Sunday morning an onshore flow continues with generally cloudy occasionally showery conditions for several days. The next ridge to bring clearing and warming may not appear for up to a week.
“A bolt from the blue!” It may sound random, but it isn’t.
Fire Danger Rating
As of June 15, 2012 See detailed weather forecast—page 2
To Report a Wildfire: 1-800-663-5555 or *5555 on your cell
Weather is certainly the topic of conversation in Coastal, and not only in reference to wildfire but also in flooding. One unit crew from Pemberton spent yesterday and today helping out EMBC in anticipation of the storm approaching the coast today. This weather system carries the dynamic instability mentioned above, and may produce thunderstorms. It is not anticipated that the thunderstorms will produce lightning, but they may produce intense, localized precipitation. Should this precipitation fall over snowpacks, rapid melting could occur, adding water to already swollen rivers. You can follow the flood watch at: http://emergencyinfobc.gov.bc.ca/
Wildfire News from the Coastal Fire Centre, BC