Advisory issued jointly with Environment Canada for coastal British Columbia at 5:00 AM PDT Monday 27 July 2009. For the latest weather updates, please click here .
An unusually lengthy period of extremely hot weather across the south coast of British Columbia will continue through most of the week. Computer models suggest the heat-wave may last 5 or possibly 6 days at some inland locales. A massive ridge of high pressure building In the upper atmosphere will result in dry weather through the end Of the week and many daily temperature records are expected to be broken.
Most importantly, the pattern of air pressure in the lower atmosphere will cause hot continental air to drift from the interior plateau to the coast. Calm or light winds on the coast will lead to stagnant air which is then subject to fierce heating by the powerful July sun. Widespread temperatures in the low to mid thirties are expected by this afternoon away from the immediate coast.
Heat-waves on the BC coast rarely last more than 3 days. After 2 or 3 days, the pressure pattern in the lower atmosphere usually changes, causing a shift in wind direction to onshore. The onshore flow of air brings cooler pacific air inland, refreshing the air and lowering the temperature by 10 degrees. In this case, the switch to onshore winds may not occur until the end of the week and temperatures in the mid-thirties will persist until then.
Records from the long-time volunteer climate station at Chilliwack suggest that since 1881 there have only been three occurrences of five or more consecutive days with maximum temperatures above 32°C.
There are 3 issues of concern:
- Health and safety effects of an extended period of hot weather.
- Deteriorating air quality from extreme heat and air stagnation.
- Increasing risk of fire due to heat and extremely dry antecedent conditions.
1. Coping with the heat
Environment Canada and the BC Centre for Disease Control (BCCDC) are reminding British Columbians to take certain precautions to protect themselves from the heat, including:
- Never leave children alone in a parked car. Temperatures can rise to 52°C (125 f) within 20 minutes in an enclosed vehicle when the outside temperature is 34°C (93 f). Leaving the car windows slightly open or "cracked" will not keep the inside of the vehicle at a safe temperature.
- Drink plenty of water and don't wait until you are thirsty to drink. Talk to your doctor if you are on water pills or currently limiting your fluid intake.
- Avoid sunburn and stay in the shade or use sunscreen with spf 15 or more.
- To keep cool on hot days, stay indoors in air-conditioned facilities or take a cool bath or shower. At indoor temperatures above 35°C, fans are not effective at preventing heat-related illness.
- Limit daytime outdoor activity to early morning and late afternoon.
- Avoid tiring work or exercise in the heat. If you must exercise, drink two to four glasses of non-alcoholic fluids each hour.
- Check regularly on older people, and those who are unable to leave their homes, for signs of heat-related illness.
There are a variety of mild to severe symptoms linked with heat-related illness, including thirst, dizziness, confusion, weakness and fainting/collapsing. These are especially likely to occur in the elderly and in persons with chronic conditions who are exposed to the heat. For more information on heat-related illness, please call BC HealthLink at 811.
2. Coping with poor air quality
Air pollution can contribute to negative health effects ranging from increased respiratory symptoms to hospitalizations and premature deaths. According to health researchers, children, the elderly and people with a pre-existing cardiac or respiratory Illness are most at risk. As the air quality deteriorates you may consider reducing or rescheduling or avoiding strenuous activities outdoors especially if you are experiencing symptoms such as coughing and throat irritation.
3. Reducing the risk of fire
All person-caused wildfires are preventable. Person-caused wildfires are those related to abandoned campfires, smoking, logging, railroads, brush or range burns, construction, recreation and arson.
- Exercise extreme caution with campfires if they are even permitted.
- Do not discard smoking materials from vehicles, use interior ashtrays.
- Lawn & farm equipment should have properly working spark arresters to prevent sparks from exiting through the exhaust pipes.
- All terrain vehicles (atvs) produce an enormous amount of heat and can ignite brush from their exhaust systems.
For the latest weather updates, please visit Environment Canada's website at: www.weatheroffice.gc.ca/warnings/sws_e.html
