Storms 3: Tornadoes

Visible tornadoes

1) recognizable from funnel cloud (most tornadoes)

2) dust and debris from ground (where the tornado hits)

3) some are invisible

Shapes for torndaoes

cones, v-shapes, wedge, cylinder, hour class, rope

Is the shape of the tornado dependent or independent of intensity classification (fujita or torro)?

its independent

Relationship between tornado and thunderstorms

• tornadoes are attached to thunderstorm

• only 20-30 percent Supercell thunderstorms produce tornadoes

• in North. Amer. T storms move SW to NE

supercell storms

• strongest

• most commonly associated w/ tornadoes

recognizing supercell rotation

• striation around mesocylone

• rotating wall cloud

wall cloud

• isolated lowering of cloud base

• above funnel

• on SW of storm

• tornadoes come from rotating wall clouds in supercells

Horizontal movement (translation) of the center of tornado

• usually SW —> NE in north America

• translation speed 0-100km

• if in car, drive perpendicular to tornado path

Rotational (tangential) speeds

rotational speeds around the center are much faster than translation speeds.

• Cause damage!

• classified by enhanced Fujita and torro

Enhanced Fujita scale (N.America)

determined by amount of damage to buildings

EF0- very weak

EF5- exceptionally strong

Torro Scale

determined by wind speed

Tornado safety

If indoors:

• below ground (basement)

• get out of mobile homes

if outdoors on foot

• get into a ditch/hole

• place body below “line of fire”

If in car

• drive away from tornado

• drive preferably to right or left of translation direction of tornado

• do NOT hide under highway bridge/ overpass

tornado outbreak

• 6 tornadoes in one day and one region, or many tornadoes during about a week

• ASSOCIATED w/ SQUALL LINES (which form along cold fronts)

• many tornado outbreaks

squall lines and tornados

• tornado outbreaks associated with squall lines

• squall lines for along cold fronts

• as cold front moves towards SE, thunderstorm along the front move NE

5 stages tornado evolution

1) thunderstorm // small dust whirl

2) funnel cloud

3) mature tornado

4) decaying “rope” stage

5) dissipating

Doppler radar

sees tornado vortex signature (TVS)

tornado nowcast warning tells you

• where its is

• where its moving

• which towns/ countries

• sirens activated

  (warning 15 min or less). immediately react

hook echo

when there a little hook shape in storm formation (reflectivity) radar

In North America, thunderstorms move in which direction?

South West —> North East

What are 2 things you can look for when trying to recognize supercell rotation?

1) striation around the mesoclyne

2) a rotating wall cloud

How long can a tornado last and how much damage can they cause?

• Rarely last for hours

• Rarely have damage path 1km wide, or 100 km long

Where go Tornados occur the most?

Midwest-south of America and South of Canada (South of Alberta, Sasketchwan, Manitoba, Ontario, and Quebec -which has the most)

What is Graupel?

small hail

Waterspout

A tornado on the water

As cold front moves SE, the thunderstorms move..

NE North East

When will you recieve a tornado warning?

15 minutes prior to a tornado hitting you b/c very hard to detect