Explained: What's causing heat wave in Northwestern US, Canada
According to the National Weather Service (NWS), in most parts of the country, temperatures must be above the historical average in an area for two or more days before the label heat wave is applied to a hot spell.
A sweltering heat wave that has settled over western Canada for several days is believed to be a contributing factor in dozens of sudden death calls received by police in the Vancouver area, authorities said on Tuesday. The temperature has reached a record 49.5 degrees Celsius.
At least 134 people have died suddenly since Friday in the Vancouver area, according to figures released by the city police department and the Royal Canadian Mounted police, reports news agency AFP.
When does rising temperature is labelled heat wave?
According to the National Weather Service (NWS), in most parts of the country, temperatures must be above the historical average in an area for two or more days before the label heat wave is applied to a hot spell, reports AFP.
How does a heat wave form?
Heat waves begin when high pressure in the atmosphere moves in and pushes warm air towards the ground. That air warms up further as it is compressed and one begins to feel a lot hotter, said the NWS.
What's causing the heat wave?
The ongoing heat wave affecting the northwestern United States and adjacent Canada is because of a combination of weather effects and climate-driven warming, said the NWS.
This heat wave is being driven by an extreme strong heat dome. Heat domes or sprawling ridges of high pressure are a staple of summer. They bring copious sunshine and sinking air that heats up as it is compressed.
This particular heat dome is unprecedented for its strength in the Pacific Northwest and it has blown away records based on measurements from three miles high in the sky down to the ground.
Places in North America currently experiencing a heat wave
One of the hottest cities on the continent on Monday was Salem, Oregon, about 45 miles southwest of Portland, where the high temperature reached 117 degrees Fahrenheit,, the NWS said.
Canada broke a national heat record on Sunday when the temperature in a small town in British Columbia reached almost 116 degrees, breaking an 84-year-old record by nearly 3 degrees.
The Northeast, under a separate weather system from the Northwest, is also in the middle of a three-day heat wave that is expected to end on Thursday. Boston reached 97 degrees on Monday, tying its record for that date, the NWS said.
When will the heat wave end?
Forecasters say that temperatures will remain hot upto next week in the Pacific Northwest. In Portland, temperatures have moderated somewhat but are expected to reach the mid-80s later in the week, said Clinton Rockey, a meteorologist with the NWS in Portland. Temperatures will remain 10 to 20 degrees above average at least until next Tuesday.
