Lecture: Tornadoes - Formation and Characteristics

Overview

• Focus: Formation and characteristics of tornadoes
• Relation to thunderstorms and severe weather
• Importance of understanding multi-panel diagrams discussed earlier

Key Concepts

Formation of Tornadoes

• Cold Front Formation: Essential for tornadoes, characterized by:
  • Low-level jet stream with warm, humid air
  • Cold fronts moving faster and overtaking warm air
  • Upper-level jet stream aiding severe thunderstorm development

Process

1. Warm Moist Air: MTG air pushed up by cold front, causing vertical motion
2. Wind Shear: Different wind directions lead to rotation

• Creates mesocyclone (broader circulation area)

3. Mesocyclone: Essential for tornado formation

• Transition to wall cloud
• Potential hook echo signature in radar, alerting meteorologists

Structure and Stages

1. Mesocyclone: First requirement, wider circulation
2. Wall Cloud: Forms from mesocyclone
3. Funnel Cloud: If touches ground = Tornado
4. Stages of Tornado:

• Condensation: Early stage, wide due to moisture
• Mature Stage: Vertical funnel, maximum wind velocity
• Weaker Stage: Funnel tilts, reduced intensity
• Decay Stage: Rope-like appearance, dissipating

Tornado Intensity and Impacts

Damage Assessment

• Depend on wind speeds and structural impacts
• Use of hook echoes and spiral damage patterns to identify tornadoes
• Comparison with other severe weather like microbursts and derechos

Tornado Characteristics

Size and Speed

• Average size: Less than ½ mile in diameter
• Largest recorded: 2 miles across
• Ground Speed: ~35 mph
• Wind Speeds: 50-300 mph
• Duration: Usually a few minutes, longest recorded ~3 hours (Tri-State Tornado, 1925)

Notable Tornadoes

• Tri-State Tornado (1925): SE Missouri to Indiana, 219 miles, ~700 deaths
• Mayfield Tornado (Recent): Northeastern Arkansas to Kentucky, significant impact

Warning Signs

• Often preceded by hail and severe weather
• Require existing severe thunderstorms or supercells

Summary

• Tornadoes are linked to atmospheric conditions detailed in this and previous lectures
• Understanding structure, formation, and warning signs are crucial for predicting and mitigating tornado impact
• Future lectures will cover tornado impacts and intensity detailed analysis.