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See Severe weather terminology for a comprehensive article on this term and related weather terms.


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Severe thunderstorm with a clear slot near main updraft core. Typically a tornado, if present, will form in this area.
A severe thunderstorm warning is issued when trained Skywarn spotters or doppler radar indicate a strong thunderstorm is producing dangerously large hail or high winds, capable of causing significant damage. It does not account for lightning or flooding. A warning must not be confused with a severe thunderstorm watch.

In the U.S., the National Weather Service defines a severe thunderstorm as having large hail being at least ¾ inch (19 mm) in diameter, high winds as being 58 miles per hour (93 km/h) or greater, producing tornadoes, or any combination of the three. But in the US State of Kansas, where severe storms are very common, NWS offices covering the state of Kansas define a Severe Thunderstorm as having large hail the size or 1 Inch or larger, winds in excess of 60MPH, producing tornadoes, or any combination of the three.

In Canada, a severe thunderstorm has one or more of the following:
  • wind gusts of >90 km/h
  • hail with a diameter of >20 mm
  • rainfall of >50 mm in an hour or >75 mm in three hours
  • tornadoes
A severe thunderstorm warning means there is significant danger for the warned area. Occasionally, severe thunderstorms can and do produce a tornado without warning. However, frequently a severe thunderstorm will produce serious wind damage as severe as a tornado. A severe thunderstorm warning can also be upgraded to a tornado warning if a tornado is detected on radar or actually spotted. Generally, but not always, a severe thunderstorm watch or tornado watch will precede a warning.

Some storms, especially in the Great Plains, may produce massive hailstones the size of baseballs or even grapefruits, falling fast enough to kill a person by repeated blunt trauma. Everyone in the path of such a storm should take cover immediately, as it is very dangerous and possibly life-threatening.

In the United States, the National Weather Service issues warnings for tornadoes and severe thunderstorms in polygon shapes. Warnings are usually deliniated by county or by a section of a county.

A similar warning is issued by Environment Canada's Meteorological Service of Canada from their offices in Vancouver, Edmonton, Toronto, Montreal and Dartmouth.

Example of a Severe Thunderstorm Warning

>
SEVERE THUNDERSTORM WARNING
OHC035-153-080300-
/O.NEW.KCLE.SV.W.0206.070808T0200Z-070808T0300Z/
BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE CLEVELAND OH
1000 PM EDT TUE AUG 7 2007
THE NATIONAL WEATHER SERVICE IN CLEVELAND HAS ISSUED A
* SEVERE THUNDERSTORM WARNING FOR...
  CUYAHOGA COUNTY IN NORTHEAST OHIO
  SUMMIT COUNTY IN NORTHEAST OHIO
* UNTIL 1100 PM EDT
* AT 950 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
  SEVERE THUNDERSTORM CAPABLE OF PRODUCING PENNY SIZE HAIL...AND
  DAMAGING WINDS IN EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR
  NORTH ROYALTON...OR ABOUT 11 MILES NORTH OF MEDINA...AND MOVING
  EAST AT 40 MPH.
* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  MACEDONIA...TWINSBURG AND SOLON
THIS IS A DANGEROUS STORM. IF YOU ARE IN ITS PATH...PREPARE
IMMEDIATELY FOR DAMAGING WINDS...DESTRUCTIVE HAIL...AND DEADLY CLOUD
TO GROUND LIGHTNING. PEOPLE OUTSIDE SHOULD MOVE TO A SHELTER...
PREFERABLY INSIDE A STRONG BUILDING BUT AWAY FROM WINDOWS.
LAT...LON 4146 8139 4127 8139 4126 8138 4126 8140
      4126 8151 4125 8167 4128 8168 4128 8179
      4137 8182
$$
FITZ

External link

Meteorological Service of Canada

United States National Weather Service

 •  • [ e]
Severe Weather Watches and Warnings
Tornado: Watch / Warning / Emergency   •   Severe Thunderstorm: Watch / Warning   •   Flash Flood: Watch / Warning / Emergency   •   Winter Storm: Watch / Warning   •   Blizzard: Watch / Warning
Severe weather terminology is different around the world, varying between regions and countries. These are articles which explain terminology in various parts of the world.
  • Severe weather terminology (United States)
  • Severe weather terminology (Canada)

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SKYWARN is a program of the United States' National Weather Service (NWS). Its mission is to collect reports of localized severe weather. These reports are used to aid forecasters in issuing and verifying severe weather watches and warnings and to improve the forecasting and
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Doppler radar uses the Doppler effect to measure the radial velocity of targets in the antenna's directional beam. The Doppler effect shifts the received frequency up or down based on the radial velocity of target (closing or opening) in the beam, allowing for the direct
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Lightning is an atmospheric discharge of electricity, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms.[1] A bolt of lightning can travel at a speed of 100000 mph (0 km/h), and can reach temperatures
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flood is an overflow of an expanse of water that submerges land, a deluge.[1] In the sense of "flowing water", the word is applied to the inflow of the tide, as opposed to the outflow or "ebb".
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severe thunderstorm watch (SAME code: SVA; sometimes referred to as "yellow box" by meteorologists and storm chasers) is issued when weather conditions are favorable for the development of severe thunderstorms.
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Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
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National Weather Service

Agency overview
Formed February 9, 1870

Jurisdiction Federal government of the United States
Headquarters Silver Spring, Maryland

Annual Budget

Agency Executive
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1 millimetre =
SI units
010−3 m 0 cm
US customary / Imperial units
010−3 ft 010−3 in
The millimetre (American spelling: millimeter, symbol mm
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Kilometres per hour (American English: kilometers per hour) is a unit of both speed (scalar) and velocity (vector). The unit symbol is km/h or km·h−1
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tornado is a violently rotating column of air which is in contact with both a cumulonimbus cloud or, in rare cases, a cumulus cloud base and the surface of the earth. Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end
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State of Kansas

Flag of Kansas Seal
Nickname(s): The Sunflower State
Motto(s): Ad astra per aspera

Official language(s) English[1]

Capital Topeka
Largest city Wichita
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tornado is a violently rotating column of air which is in contact with both a cumulonimbus cloud or, in rare cases, a cumulus cloud base and the surface of the earth. Tornadoes come in many sizes but are typically in the form of a visible condensation funnel, whose narrow end
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tornado warning is issued when:
  • a tornado is reported on the ground or is indicated on doppler radar
  • a waterspout is headed toward landfall
  • a funnel cloud is reported in the sky

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severe thunderstorm watch (SAME code: SVA; sometimes referred to as "yellow box" by meteorologists and storm chasers) is issued when weather conditions are favorable for the development of severe thunderstorms.
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tornado watch (SAME code: TOA; sometimes referred to as a "red box" by meteorologists and storm chasers) is issued when weather conditions are favorable for the development of severe thunderstorms that are capable of producing tornadoes.
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Great Plains are the broad expanse of prairie and steppe which lie east of the Rocky Mountains in the United States and Canada. This area covers parts of the U.S. states of Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas and Wyoming, and
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Citrus paradisi
Macfad.

The grapefruit is a sub-tropical citrus tree grown for its fruit which was originally named the "forbidden fruit" of Barbados.
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In medical terminology, blunt trauma, blunt injury, non-penetrating trauma or blunt force trauma refers to a type of physical trauma caused to a body part, either by impact, injury or physical attack; the latter usually being referred to as blunt force trauma.
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Motto
"In God We Trust"   (since 1956)
"E Pluribus Unum"   ("From Many, One"; Latin, traditional)
Anthem
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National Weather Service

Agency overview
Formed February 9, 1870

Jurisdiction Federal government of the United States
Headquarters Silver Spring, Maryland

Annual Budget

Agency Executive
..... Click the link for more information.
POLYGONE is an Electronic Warfare Tactics Range located on the border between France and Germany. It is one of only two in Europe, the other being RAF Spadeadam.

The range, also referred to as the Multi-national Aircrew Electronic Warfare Tactics Facility (MAEWTF), is
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Parliamentary Secretary Mark Warawa
Established 1971

Responsibilities Meteorological Service of Canada

Parks Canada

Canadian Ice Service

Canadian Environmental Assessment Agency

Water Survey of Canada

National Water Research Institute
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The Meteorological Service of Canada (MSC) is a division of Environment Canada, which primarily provides public meteorological information and weather forecasts and warnings of severe weather and other environmental hazards.
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Vancouver
Downtown Vancouver as seen from Fairview Slopes north across False Creek

Flag
Coat of arms
Nickname: Van City
Motto: "By Sea, Land, and Air We Prosper"
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City of Edmonton
Edmonton's City Hall

Flag
Coat of arms
Nickname: City of Champions, Festival City, Gateway to the North, E-Town, River City
Motto:
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City of Toronto

Flag
Coat of arms
Nickname: T.O., Hogtown, The Big Smoke, T-Dot, Toronto the Good
Motto: Diversity Our Strength
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Ville de Montréal
City of Montreal

Flag
Coat of arms
Nickname: 5-1-4, MTL, Heavy MTL, Mount Real, Real City
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Dartmouth, Nova Scotia
Location of Dartmouth, Nova Scotia
Location of Dartmouth, Nova Scotia
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