Tornado Warning Signs

Cloud Formations

Wall Cloud

A rotating lowering of clouds beneath thunderstorm base:

• Circular or block-shaped
• Rotates visibly
• Extends toward ground
• Often precedes tornado
• Occurs beneath supercell

Full wall cloud guide →

Funnel Cloud

Rotating column of cloud extending downward:

• Visible from ground to cloud base
• Not yet touching ground
• Precursor to tornado
• If reaches ground = tornado

Mesocyclone

Large rotating updraft in supercell:

• Visible rotation in main updraft
• Indicated by cloud rotation
• Sign of severe storm

Beavertail Cloud

Long, flat cloud extending from wall cloud:

• Associated with mesocyclone
• Often precedes tornado
• Indicates significant storm structure

Sky Color

Green Sky

Distinct greenish tint to sky:

• Common with hail-laden storms
• Doesn't guarantee tornado but indicates severe storm
• Light scattered through hail
• Warning sign of severe weather

Deep Dark

Dark, ominous clouds:

• Very dark storm base
• Ominous appearance
• Deep thunderstorm indicator
• Warrants shelter preparation

Sudden Sky Change

Rapid change from normal to dark/threatening:

• Storm developing rapidly
• Time to take shelter
• Not gradual weather change
• Severe weather potential

Wind Indicators

Wind Direction Shifts

Rapid changes in wind direction:

• Wind suddenly opposite of normal
• Multiple direction changes
• Indicates rotation
• Storm dynamics changing

Wind Speed Changes

Sudden gusts or calms:

• Strong, sustained winds
• Sudden lulls before storms
• Fluctuating wind speeds
• Storm approach indicators

Strange Calm

Unusual quiet before tornado:

• Sudden lack of wind
• Silent atmosphere
• Precedes some tornado events
• Cause for immediate attention

Sound Indicators

Freight Train Roar

Continuous low-frequency roar:

• Sound of tornado
• Distance can be miles
• Sustained low rumble
• Immediate shelter needed

How loud is a tornado? →

Continuous Thunder

Constant thunder without pause:

• Indicates severe storm
• Multiple lightning strikes
• Sustained activity
• Warning worthy

Sudden Silence

Sudden absence of wind sound:

• Deceptive calm
• Pre-tornado phenomenon
• Storm dynamics shifting

Pressure Changes

Ear Popping

Pressure changes noticeable in ears:

• Sudden pressure drops
• Comparable to elevation change
• Storm dynamics
• Attention indicator

Barometric Pressure

Weather stations show:

• Rapid pressure drops
• Storm approaching
• Severe weather potential

Weather Radar Signs

Hook Echo

Curved feature on radar:

• Indicates tornado potential
• Combined with rotation
• Triggers warnings

Hook echo details →

Debris Signature

Dual-polarization detection:

• Debris in air
• Confirms tornado
• Tornado on ground

Environmental Indicators

Sudden Temperature Drop

Rapid cooling before storm:

• Cold air mass arriving
• Storm approaching
• Severe weather indicator

Debris in Air

Random debris flying:

• Tornado already active
• Debris cloud visible
• Immediate shelter needed

Hail

Severe storms produce hail:

• Baseball-size hail = severe storm
• Golf-ball hail = severe storm
• Marble-size = warning worthy
• Combined with rotation = tornado potential

Time of Day Considerations

Day Warning Signs

Daytime allows visual observation:

• Cloud formations visible
• Storm structure identifiable
• Approaching danger recognized
• Visual warning signs

Night Warning Signs

Nighttime harder to observe:

• Lightning illuminates
• Sound most reliable
• NOAA weather radio critical
• Warning apps essential

What to Do When You See Signs

Immediate Actions

1. Get to shelter immediately
2. Interior room, lowest floor
3. Away from windows
4. Cover head
5. Turn on NOAA weather radio
6. Wait for all-clear

Warning Priority

Warning signs indicate potential, but:

• NWS warnings are official
• Warning signs supplement warnings
• Don't rely solely on visual observation
• Layer multiple sources

Bottom Line

Tornado warning signs include wall clouds, funnel clouds, green sky, wind shifts, freight train sounds, and other environmental indicators. Recognize these signs to take shelter earlier and stay safer. But rely on official NWS warnings for definitive tornado information. Warning signs supplement, don't replace, official warnings.