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Tornadoes and funnel clouds
Any tornado or funnel cloud should be reported immediately. This includes evidence
of tornado debris cloud even if no funnel is visible. Also, clear signs of rotation
or other cloud features that would suggest the risk of tornadoes should be reported.Remember,
a storm need not be tornadic to pose significant risks (so be on the lookout
for risks from straight-line winds, hail and flooding, too).
A detailed discussion of tornado/funnel cloud features is given on page 33.
To test your sightings, also refer to page 37 for examples of "false funnels",
or tornado look-alikes.
A roaring sound near or under a severe storm should be reported because it
may be caused by churning debris from a nearby tornado that you cannot see clearly.
A softer, steady roaring or thundering sound can be produced by large hailstones
colliding in mid-air nearby, and this, too, should be reported.
Other situations to report
Any weather event that poses a hazard to life or property should be reported,even
if not associated with thunderstorms or summer weather. A few examples might
be freezing rain,dense fog, widespread strong wind causing damage, blizzards
or snowqualls, and extreme snowfall amounts. For snow and fog, the pertinent
factor is the occurrence of near-zero visibility.
Waterspouts, large dust devils, or other unusual phenomena also warrant mentioning.
Test your sightings of strange clouds and sky conditions around storms against
the likely causes and features discussed in the What to watch for section on
page 13.
A quick reference table of what and how you should report is given on the
outside back cover.
Reporting procedures
The two essentials of any report are speed and accuracy. Every minute saved
is a minute applied to releasing a new or updated warning. The danger may have
already passed your area but others down the road are still awaiting its arrival.
Precise and thorough descriptions and measurements are also important. Whenever
possible, give exact figures for damage, e.g., the diameter of a snapped tree
limb or trunk. Measure large hailstones with a ruler. Heavy rain can be measured
from the water depth in a can put out in the open.
Even after a severe event has long passed, your discoveries of damage while
driving around or talking with neighbours are invaluable for verifying the occurrence.
You may run into someone who witnessed a tornado but isn't part of this program
or come across signs of damage in a remote rural area, and this information
will help the weather office complete its records.
Let us know what you see
As a weather watcher you are the eyes and ears of MSC, helping us to track
and confirm what is happening on the ground on days when there is a potential
for severe weather.
Most storms are not tornadic, but they may still pose significant risks to
public safety. We would like to hear from you when you can supply us with details
which help us ascertain the degree of risk to the public.Your observations of
the following storm features are particularly helpful:
- lowerings and wall cloud development
- features associated with strong outflow - shelf cloud,
roll cloud, blowing dust
- microburst features - rain foot, dust foot or dust
plumes
- clear supercell indicators - persistent overshooting
top, curved cloud striations (mesocyclone),etc.
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Created :
2002-08-26
Modified :
2002-12-19
Reviewed :
2002-12-19
Url of this page : http://www.msc.ec.gc.ca /education/severe_weather/page47_e.cfm
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