Storms 3 Flashcards
Difference between funnel cloud vs tornado
Funnel cloud before it touches ground
Tornado once it touches ground
True or false: Shape is dependent on intensity classification
false, shape does not tell us about the intensity
Do invisible tornadoes exist?
oui
Most tornadoes are made visible by…?
- cloud-water droplets (the funnel cloud)
and/or
- dust and debris from the ground (debris cloud)
What are some possible tornado shapes?
cone
V-shaped
wedge
cylinder
hourglass
rope
Strong tornadoes are most likely associated with…?
supercell storms
In North America, most Tstorms move from ___ to ___
SW towards NE
what are tornadoes attached to?
Thunderstorms!
True or false: only a small percentage of supercell Tstorms produce tornadoes
True: 20% - 30%
How to recognize supercell rotation
- Striations around mesocyclone
- rotating wall cloud
What is a funnel cloud
Water condensation funnel / cloud-water droplets
-> use this term before it touches ground
What is a wall cloud
isolated lowering of cloud base beneath rain-free Tstorm base
Where is the wall cloud
- beneath rising cumulus towers
- on SW flank of the storm
- outside the precipitation region!
Where do tornadoes come from, in a supercell storm?
they come from rotating wall clouds
True or false: if we are in a car, we can easily drive away from most tornadoes
true, by taking a perpendicular path to the tornado path
What are the translation speeds of the centre of a tornado?
Horizontal movement can be between
0 - 100 km/hr
Are tangential speeds faster or slower than translation speeds?
i.e. rotational speeds, they are much faster!
True or false: Translational winds causes the damage
False:
Tangential (rotational) winds cause the damage
What is the Enhanced Fujita Scale? Where is it used?
Rates tornado intensity by amount of damage to buildings
- EF0 (break windows) to EF5 (destroy buildings)
- used in N. America
What is the TORRO scale? Where is it used?
Determined by wind speed
- used in Europe
Describe the EF ratings
EF0
- trees snapped or toppled
EF1
- roof damage, windows broken
EF2
- roofs torn off, large trees snapped or uprooted
EF3
- destroyed homes, damage to large buildings
EF4
- homes are levelled, cars thrown a ways away
EF5
- completely levelled AND homes swept away, concrete structures badly damaged, trees completely debarked
Most tornadoes in Canada are ranked what EF scale?
EF0
How long do tornadoes normally last?
short lived, usually just minutes
Describe a tornado’s typical damage path
Narrow (width of house to size of city blocks)
paths often one to tens of km long
Tornadoes RARELY
- last for hours
- have damage paths >1km wide, >100km long
In the case of a tornado, what are some safe places to be if you are indoors?
below ground (storm cellar or basement)
get out of mobile homes!!
What is the worse place to be in a tornado
in a mobile home
In the case of a tornado, what are some safe places to be if you are outdoors?
get into a ditch
place body below “line of fire” of moving debris
True or false: in a tornado, you could hide under highway bridges or overpasses
False: do NOT hide under highway bridge or overpass
What country do tornadoes occur the most?
North America
75%
Are tornadoes in Vancouver common?
Nope they are very rare
Where is Tornado Alley?
parts of Texas / OKC
(east side of US)
Greatest tornado frequency in Canada
South Quebec / Ontario
Graupel is
small hail
What are tornado Outbreaks
6 tornadoes in one day and one region
OR
many tornadoes in a week
How often do outbreaks occur?
almost ever year in N America
Tornado outbreaks are often associated with____
Squall Lines
Squall lines often form along
cold fronts
As cold front moves towards SE, Tstorms move
toward NE
Describe the 5 stages of Tornado Evolution
- Thunderstorm, dust whirl
- Funnel cloud
- Mature tornado
- Decaying “rope”
- Dissipating
True or False: Forecasting tornadoes is not difficult
False: forecasting tornadoes is very difficult
Tornado Watch
6 - 12 hr forecast
Tells broad region where tornadoes are likely later in day
- can continue with dailies but should monitor emergency news
Tornado Warning
Tornado actually detected NOW
“Nowcast” warning tells
- where tornado is / moving
- warn specific towns in expected path
- tornado sirens in towns are activated
What can detect tornadoes
Doppler radar -> sees vortex signature
Human spotter
Tornado warnings come ___ prior to a tornado hitting
15 mins or less
- must immediately take shelter
