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ENVIRONMENT IN CANADA - WEATHER CONDITIONS
ENVIRONMENT IN CANADA - WEATHER WATCHES, WARNINGS AND ADVISORIES
For the safety of people and property,
Environment Canada issues severe weather warnings and watches and
advisories to the public via the media, weather outlets and Weatheradio
Canada.
A
WEATHER WATCH
alerts you that conditions are favourable for the development of severe
weather. Watch the skies and listen for updated watches and possibly
weather warnings.
A
WEATHER
WARNING
alerts you that severe weather is occurring or that hazardous weather is
highly probable. Severe thunderstorm or tornado warnings may be issued
less than one hour in advance. Other weather warnings may be issued six to
twelve hours in advance.
A
WEATHER
ADVISORY
means actual or expected weather conditions may cause general
inconvenience or concern, but do not pose a serious enough threat to
warrant a weather warning. An advisory may also be used when conditions
show signs of becoming favourable for severe weather when the situation is
not definite enough or too far in the future to justify a warning.
This fact sheet lists some
of the more common weather watches, warnings and advisories issued by
Environment Canada. Note that criteria for warnings are established to
meet local and regional needs and may vary slightly from region to region
across Canada. Contact your nearest weather outlet to confirm criteria for
your area.
Severe thunderstorm watch
Conditions are favourable for the development of severe thunderstorms
with large hail, heavy rain, intense lightning or damaging winds within
the areas and times specified in the watch. You should secure or put away
loose objects such as outdoor furniture, put your car in the garage, bring
livestock to shelter and listen carefully for an updated weather report.
Severe thunderstorm warning
A severe storm has developed, producing one or more of the following
conditions: heavy rain, damaging winds, hail of at least 20 mm in diameter
or intense lightning. Severe thunderstorms may also produce tornadoes. The
storm's expected motion and developments will be given in the warning. If
you are in the area specified, take shelter indoors.
Tornado watch
Conditions are favourable for the development of tornadoes within the
areas and times specified in the watch. Be prepared to take shelter,
preferably in the lower level of a sturdy building.
Tornado warning
One or more tornadoes are occurring in the area specified. The expected
motion, development and duration will be given in the warning. If you are
in the path of a tornado, take emergency precautions immediately. If you
are near the area specified in the warning, be alert for the development
of additional tornadoes or severe thunderstorms.
Freezing rain warning
Expect slippery walking and driving conditions, and possible damage to
trees and overhead wires due to rain freezing on contact to form a coating
of ice. Avoid travel.
Heavy rain warning
Issued when heavy or prolonged rainfall is sufficient to cause
local/widespread flooding. Expect 50 mm of rain over 12 hours or less, or
80 mm of rain in less than 24 hours.
Frost warning
A frost warning is issued when air temperatures are expected to fall to
near freezing or below during the growing season, approximately May 15 to
October 15. Protect your plants!
Wind warning
Expect winds blowing steadily at 60 km/h or more, or winds gusting to
90 km/h or more, for at least one hour. Secure or put away loose objects
such as outdoor furniture, put your car in the garage, and bring livestock
to shelter.
Marine wind warnings
- Small Craft Warning:
Issued if winds of 20 to 33 knots are
forecast. Gale Warning:
Issued if
winds of 34 to 47 knots are forecast.
Storm Warning:
Issued if winds of 48 to 63 knots are forecast.
Hurricane Force Wind Warning:
Issued for winds of 64 knots or greater.
Dust storm advisory
Issued in the prairie provinces when blowing dust caused by high winds
has reduced visibility to one kilometre or less. Under extreme conditions
of widespread zero visibility, this bulletin may be issued as a warning.
Dust can impair breathing for people and animals, and make travel
hazardous.
Blizzard warning
Expect snow or blowing snow, with a severe windchill and visibility
reduced to less than one kilometre, for four hours or more. Stock up on
heating fuel and food. Stay indoors and wait out the storm.
Heavy snowfall warning
Expect a snowfall of 10 cm or more (15 cm or more in Ontario) in 12
hours or less. Travel could become hazardous.
Winter storm warning
Issued in Ontario when two or more winter conditions reach warning
proportions (eg. wind and snow, or freezing rain followed by heavy
snowfall). Be prepared to cancel travel plans and stay indoors.
Windchill warning
Expect very cold temperatures combining with wind to create outdoor
conditions hazardous to human activity. Be prepared to stay indoors.
Cold wave advisory
Temperatures are expected
to drop by 20 Celsius or more within 18 hours. Dress warmly and check the
weather forecast before travelling or venturing outdoors.
ENVIRONMENT IN CANADA - TOP WEATHER EVENTS DURING LAST 20 YEARS :
- Blizzard Maroons PEI - February 22-26, 1982
.
A huge snowstorm with up to 60 cm of snow, 100 km/h winds, zero visibility
and wind chills of -35°C paralyzed the Island for a week. The storm buried
vehicles, snowplows and trains in 5- to 7-metre drifts and cut off all
ties with the mainland.
Ocean Ranger Disaster - February 15, 1982.
Bad weather caused the sinking of the largest semi-submersible drilling
rig in the world, 300 km east of Newfoundland. In total, 84 people died in
the world's second worst disaster involving an offshore drill ship. Winds
of 145 km/h, waves of 21 metres and high seas hampered rescue efforts.
Newfoundland Glaze Storm Cuts Power to 200,000 - April 13, 1984.
Residents of the Avalon Peninsula were without electricity for days when
cylinders of ice as large as 15 cm in diameter formed on overhead wires.
The severe, two-day ice storm covered all of southeastern Newfoundland
with 25 mm of glaze.
Tornadoes in Barrie and Central Ontario - May 31, 1985.
Three confirmed tornadoes struck the Ontario communities of Barrie, Grand
Valley, Orangeville and Tottenham. The Barrie tornado was the fourth most
damaging and had the longest track (200 km) in Canadian history. In all,
the family of tornadoes killed 11 people, injured hundreds of others, and
destroyed or damaged 1,000 buildings.
Worst Air Crash in Canada - December 12, 1985.
An Arrow Airlines DC-8, after refueling in Gander en route to Kentucky,
crashed seconds after take-off, killing 248 members of the US 101st
Airborne Division and 8 crew. Just before the crash, freezing drizzle and
snow grains were reported. The temperature was -4.2oC and winds
were light from the west.
Black Friday Tornado - July 31, 1987.
One of Canada's most intense tornadoes ever struck Edmonton and killed 27
people -- the second worst killer tornado in Canada. Winds reached 400
km/h, cutting a swath of death and destruction 40 km long and as much as 1
km wide. In addition, hail as large as softballs and 40 to 50 mm of
flooding rain fell on the city.
$4 Billion Drought - September 1987-August 1988.
Across the southern Prairies, the hottest summer on record, combined with
half the normal growing season rainfall and a virtually snow-free previous
winter, produced a drought that rivaled the 1930s in terms of intensity
and duration of the dry spell. About 10% of farmers and farm workers left
agriculture in 1988. Effects of the drought were felt across the country
as lower agricultural yields led to higher food and beverage prices for
consumers.
Warmest Winter Olympics - February 1988.
The Winter Olympics in Calgary experienced some of the warmest
temperatures ever for late February. On February 26, Miami's high
temperature of 19.4°C was only a shade warmer than Calgary's maximum of
18.1°C.
Record Wind Chill - January 28, 1989.
It was bad enough when the temperature dropped to -51°C in Pelly Bay, NWT
but the wind made the air feel even colder when the wind chill equivalent
reached -91°C.
Hailstorm Strikes Calgary - September 7, 1991.
A supper-hour storm lasting 30 minutes dropped 10-cm diameter hail in
Calgary subdivisions, splitting trees, breaking windows and siding, and
crushing birds. Homeowners filed a record 116,000 insurance claims, with
property damage losses exceeding $300 million -- the most destructive
hailstorm ever and the second costliest storm in Canada.
Canada's Only World-Weather Record - September 11, 1995.
The QE2 ocean liner was struck by a 30-metre wave during Hurricane Luis
off the coast of Newfoundland, marking the largest measured wave height in
the world. The massive storm covered almost the entire North Atlantic,
almost 2,000 km across.
Saguenay Flood - July 18-21, 1996.
Canada's first billion dollar disaster, this deluge triggered a surge of
water, rocks, trees and mud that killed 10 people and forced 12,000
residents to flee their homes. Many roads and bridges in the region
disappeared.
Hailstorm Pounds Calgary and Winnipeg - July 24, 1996.
Orange-sized hailstones racked up close to $300 million in property
losses. Hail clogged storm sewers, causing extensive flooding in both
cities and in Winnipeg, at least a third of the cars damaged had to be
written off.
Red River Flood Levels Highest of Century - April-May, 1997.
About 2,000 square km of valley lands were flooded as the Red River rose
12 m above winter levels. Thousands of volunteers and soldiers fought
rising waters for days. Damage estimates reached a half a billion dollars.
Okanagan's $100 million Hailstorm - July 21, 1997.
A destructive hail and wind storm ripped through the orchards of the
Okanagan. It was the worst storm in memory with nearly 40% of the crop
deemed unsuitable for fresh market. The rain and hail was accompanied by
winds gusting to 100 km/h that capsized boats in the interior lakes, and
caused power outages and traffic accidents.
Ice Storm of the Century - January 4-9, 1998.
One of the most destructive and disruptive storms in Canadian history hit
Eastern Canada causing hardship for 4 million people and costing $3
billion. Losses included millions of trees, 130 transmission towers and
120,000 km of power and telephone lines. Power outages lasted from several
hours to four weeks.
A Year-Long Heat Wave - 1998.
Canada experienced its second warmest winter and warmest spring, summer
and fall on record. Temperatures in 1998 were an average of 2.4 degrees
warmer than normal and likely the warmest year this century.
Costliest Forest Fire Season on Record - 1998.
Flames from forest fires destroyed 4.6 million hectares of forests, about
50% more than the normal amount. The 10,560 fires were the greatest number
in 10 years.
Toronto's Snowstorm of the Century - January 2-15, 1999.
A series of storms stalked the city, dumping nearly a year's amount of
snow in less than two weeks. In all, the city recorded the greatest
January snowfall total ever with 118.4 cm and the greatest snow on the
ground at any one time with 65 cm. The storms cost the city nearly twice
the annual budget in snow removal.
Greatest Single-Day Snowfall Record - February 11, 1999.
Tahtsa Lake, BC, received 145 cm of snow, a new Canadian single-day
snowfall record, but well below the world's record of 192 cm at Silver
Lake, Colorado on April 15, 1921.
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