Severe weather terminology (Canada)

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This article describes severe weather terminology used by the Meteorological Service of Canada, a branch within Environment and Climate Change Canada. The article primarily describes various weather warnings, and their criteria. Related weather scales and general weather terms are also addressed in this article. Some terms are specific to certain regions.[citation needed]

Warning categories

Severe weather bulletins are issued as a watch or a warning, depending on the risk or severity of the event. Less severe events that could be a cause for concern will be issued as a special weather statement or Advisory.[1]

Updated statements, watches, and warnings are re-issued or upgraded if required.[1]

Weather warnings

Weather watches and warnings are issued when potentially hazardous weather is occurring or is forecast for the short term period. Some of those bulletins have been changed on April 8, 2014 and below is a list and definitions of the up-to-date watch and warning.[2]

Local-scale/Summer severe weather

Due to its local-scale nature, a watch is typically issued in advance for public forecast areas where conditions may be favourable for the development of severe weather. A warning is issued for areas where severe weather is imminent or occurring. Unlike other warnings, these are issued for smaller warning areas within its regular forecast region.

Public bulletins will often mention the possibility of tornadoes; if a tornado is spotted or conditions are favourable enough for tornado development, the warning will be upgraded accordingly.[2]

Hurricanes and other tropical systems

Winter weather

General warnings

Marine warnings

Tsunami

Areas covered by the Tsunami Alerts

Advisories and Special Weather Statements

Advisories

Advisories are issued as part of a special weather statement in a similar format to that of an official warning. Unlike warnings, however, these types of bulletins describe exceptional weather events that are generally not considered hazardous, but could be a potential concern to the public (for example, High Humidex that can affect certain age groups). Advisories and Special Weather Statements can also be issued in advance to a more serious weather event, or before a higher level alert is issued (for example, a Weather Advisory is issued before a Tornado Watch when the possibility of cold core funnel clouds is present, but not likely). As well, a Special Weather Statement may be issued to alert the public to potentially hazardous weather in the long term forecast.

Commonly issued advisories as of April 8, 2014 include:[2]

Hurricane Information Statements

Issued when a tropical system threatens Canadian coastal waters or land. The statement includes public and marine impacts and warning summary, location and expected motion of the storm and technical discussion. This information is updated at least every six hours.[citation needed]

Thunderstorm Potential

Issued in Ontario only, these statements are issued twice daily from May through September. These statements are issued whenever there is a thunderstorm risk, and does not only apply for a risk of severe thunderstorms.

Related weather scales as defined by Environment Canada

Enhanced Fujita Scale

The Enhanced Fujita Scale (EF) is a scale for rating tornado intensity based on the damage on human-built structures and vegetation. While the United States adopted the Enhanced Fujita Scale in 2007, Environment Canada continued to use the original Fujita Scale to assess tornado intensity until April 18, 2013, when the agency adopted the Enhanced Fujita Scale.[3] Tornadoes exceeding F2/EF2 intensity are rare in Canada, although some tornadoes, such as the Edmonton Tornado in 1987, have been as strong as F4. The only F5/EF5 tornado recorded in Canada to date was the Elie, Manitoba tornado in 2007.[citation needed]

Saffir-Simpson Hurricane Scale

The Saffir-Simpson Hurricane Scale is used by the Canadian Hurricane Centre for hurricanes affecting the East Coast of Canada. The Scale ranges from Category 1, the weakest, to Category 5, the strongest with sustained winds exceeding 250 km/h (160 mph; 130 kn).[citation needed]

See also

References

  1. ^ a b c https://weather.gc.ca/business/index_e.html
  2. ^ a b c Meteorological Service of Canada. "Public Alerting Criteria". Retrieved 2014-05-23.
  3. ^ Assessing tornado damage: EF-scale vs. F-scale. Retrieved from "Archived copy". Archived from the original on April 27, 2013. Retrieved April 4, 2014.CS1 maint: archived copy as title (link).