2025 Atlantic Hurricane Season – Track The Tropics

Severe Weather Season 101

What “Severe Weather” Actually Means

Meteorologists define severe thunderstorms using specific criteria used by the National Oceanic and Atmospheric Administration and the Storm Prediction Center.

A thunderstorm is severe if it produces at least one of these:
• Hail 1 inch diameter or larger (quarter size)
• Wind gusts 58 mph or stronger
• A tornado

Other dangerous effects can include:
⚡ frequent lightning
🌧 flash flooding
🌪 rotating storms capable of tornadoes

Severe weather follows warm air moving northward in spring.

Typical U.S. timeline....
January–February
• Gulf Coast severe storms
• Florida, Louisiana, Mississippi, Alabama
March–April
• Deep South becomes very active
April–May
• Peak tornado season for the Southeast
May–June
• Peak tornado season for the Plains
June–July
• Northern Plains and Midwest
Late summer
• Severe storms shift north into the Dakotas and Upper Midwest

Why does the U.S. Gets So Much Severe Weather??

The U.S. is basically perfectly designed for violent storms because three air masses collide...

Warm moist air...
• Comes from the Gulf of Mexico
Cold dry air...
• Comes from Canada
Hot dry air...
• Comes from the Southwest deserts

When these collide with strong winds aloft, storms can rotate and intensify.

The Key Ingredients for Severe Storms

Meteorologists look for four main ingredients:
1️⃣ Moisture
Warm humid air fuels storms.
Typical source:
• Gulf of Mexico moisture
2️⃣ Instability
Warm air near the surface and colder air above.
This creates rising air.
Higher instability = stronger storms.
3️⃣ Lift
Something must trigger storms.
Examples:
• Cold fronts
• Warm fronts
• Drylines
• Outflow boundaries
4️⃣ Wind Shear
Wind changing direction or speed with height.
Wind shear is what allows storms to rotate.

Supercells (The Most Dangerous Storms)

The most powerful severe storms are called supercells.

Characteristics:
🌪 rotating updraft (mesocyclone)
🌧 very large hail
💨 destructive winds
🌪 strong tornado potential

Supercells can last hours, unlike normal storms.

Tornado Alley vs Dixie Alley

Tornado Alley
Classic U.S. tornado region.
States include:
• Texas
• Oklahoma
• Kansas
• Nebraska

Why it's active:
• Dryline collisions
• Huge instability
• Strong jet stream winds

Dixie Alley
Southeast tornado hotspot.
States include:
• Mississippi
• Alabama
• Tennessee
• Louisiana

Why it's dangerous:
⚠ storms often occur at night
⚠ more trees and hills
⚠ more populated areas

Types of Severe Thunderstorms

Single Cell
Short-lived storms (30–45 minutes).
Usually produce:
• heavy rain
• lightning

Multicell Clusters
Groups of storms.
Common hazards:
• strong winds
• hail

Squall Lines
Long lines of storms along a cold front.
Often produce:
💨 damaging straight-line winds
🌧 heavy rain
⚡ frequent lightning

Sometimes they form derechos (long-lived windstorms).

Supercells
The most dangerous storm type.
Produce:
⚠ giant hail
⚠ violent tornadoes
⚠ destructive winds

The Role of the Jet Stream

The jet stream acts like a steering wheel for storms.
Strong jet stream = stronger severe weather setups.
It also provides:
• wind shear
• storm organization
• large storm systems

Climate Patterns That Influence Severe Weather

El Niño
Often shifts severe weather southward.
More storms:
• Gulf Coast
• Southeast

La Niña
Often increases severe weather in:
• Plains
• Midwest

How Meteorologists Predict Severe Weather

Forecasting happens in layers of increasing confidence.
Days in advance
Meteorologists watch:
• moisture return
• jet stream patterns
• cold fronts

3–5 days out
The Storm Prediction Center issues outlooks.
Risk levels:
🟩 Marginal
🟨 Slight
🟧 Enhanced
🟥 Moderate
🟪 High

Day of event
Storm Prediction Center issues:
⚠ Severe Thunderstorm Watches
🌪 Tornado Watches

Storm happening
Local National Weather Service offices issue:
🚨 Warnings
These mean: Severe weather is occurring or imminent.

Radar Signatures Storm Trackers Watch

Storm trackers and meteorologists watch radar for:
Hook echo
• Classic tornado signature
Debris ball
• Tornado lofting debris
Bow echo
• Damaging wind events
Velocity couplets
• Strong rotation

Severe Weather Safety Basics

When a tornado warning is issued:
Go to:
• lowest floor
• interior room
• away from windows

Best places:
✔ basement
✔ bathroom
✔ closet

Avoid:
❌ mobile homes
❌ vehicles
❌ large open rooms

Why Spring Is the Peak Season

Spring has the perfect combination of:
🔥 increasing warmth
❄ leftover cold air
💨 strong jet stream
This combination creates volatile atmospheric setups.

✅ Quick Summary...

Severe weather needs:
1️⃣ Moisture
2️⃣ Instability
3️⃣ Lift
4️⃣ Wind shear

When all four combine, you can get:
🌩 supercells
🌪 tornadoes
🧊 giant hail
💨 destructive winds