Storm Systems - Hurricanes, Tornadoes & More

🌀

Hurricane

Atlantic & East Pacific

🌡️

>26.5°C

Sea temp

📅

Jun-Nov

Season

💨

>119

km/h

Formation Requirements

Ocean temp >26.5°C to 50m depth
Low wind shear (vertical)
5°+ from equator (Coriolis)
Pre-existing disturbance
High humidity mid-levels

Saffir-Simpson Scale

Cat 1

119-153 km/h

Cat 2

154-177 km/h

Cat 3

178-208 km/h

Cat 4

209-251 km/h

Cat 5

>252 km/h

🔬 Detailed Formation Process ▼

1

Tropical Disturbance: Cluster of thunderstorms over warm ocean. Organized circulation begins to develop.

2

Tropical Depression: Winds 0-62 km/h. Closed low-pressure center forms. Numbered by forecasters.

3

Tropical Storm: Winds 63-118 km/h. Given a name. Spiral bands develop. Eye starts forming.

4

Hurricane: Winds >119 km/h. Clear eye forms. Eyewall contains strongest winds. Can reach Cat 5 if conditions ideal.

Energy Source

Latent heat from condensation powers the storm. Warm ocean evaporates water → rises → condenses → releases heat → strengthens updrafts → pulls in more air → positive feedback loop. Storm dies when it hits land or cold water.

📊 Historical Records & Notable Storms ▼

Storm	Year	Category	Record
Bhola Cyclone	1970	Cat 3	Deadliest: 300,000-500,000 deaths (Bangladesh)
Patricia	2015	Cat 5	Strongest: 345 km/h winds (Eastern Pacific)
Katrina	2005	Cat 5	Costliest: $125 billion damage (US Gulf Coast)
Wilma	2005	Cat 5	Lowest pressure: 882 mb (Atlantic record)
Allen	1980	Cat 5	Longest Cat 5 duration: 72 hours
Mitch	1998	Cat 5	2nd deadliest Atlantic: 11,000+ deaths
Harvey	2017	Cat 4	Wettest: 1,539mm rainfall (Texas)
Dorian	2019	Cat 5	Strongest Atlantic landfall: 298 km/h (Bahamas)

⚠️ 2005 Atlantic Season - Record Breaker

28 named storms (ran out of names, used Greek alphabet)
15 hurricanes (7 major)
4 Category 5 hurricanes (Dennis, Emily, Katrina, Rita, Wilma)
Katrina, Rita, Wilma all in top 10 costliest ever

⚠️ Quick Records

Deadliest: Bhola 1970 (500,000 deaths)
Costliest: Katrina 2005 ($125B)
Strongest: Patricia 2015 (345 km/h)

🌀

Typhoon

Northwest Pacific

🗺️

NW Pacific

Region

📅

May-Nov

Peak

📊

~26/yr

Average

Same as Hurricane, Different Name

Typhoons are the most frequent tropical cyclones globally. The warm Pacific pool provides ideal conditions. Japan, Philippines, Taiwan, China, Korea most affected.

Super Typhoons (Cat 4-5 equivalent)

Haiyan 2013: 315 km/h (Philippines)
Tip 1979: Largest ever (2,220 km diameter)
Goni 2020: 315 km/h at landfall

🌊 Why NW Pacific Has Most Typhoons ▼

Perfect Conditions Year-Round

Warm Pool: Western Pacific warmest ocean area globally (28-30°C)
No "off-season": Can form any month (unlike Atlantic)
Vast fetch: Long ocean path to strengthen before landfall
Monsoon trough: Constant supply of disturbances
ITCZ: Intertropical Convergence Zone provides energy

Annual Statistics

Average per year: 26 typhoons

Super typhoons: ~4-5 per year

% of global tropical cyclones: ~30%

💨 Super Typhoon Hall of Fame ▼

Name	Year	Peak Winds	Notable For
Tip	1979	305 km/h	Largest diameter ever: 2,220 km
Haiyan	2013	315 km/h	Strongest at landfall: 6,300 deaths (Philippines)
Goni	2020	315 km/h	Tied strongest landfall (Philippines)
Meranti	2016	315 km/h	Strongest of 2016 globally
Mangkhut	2018	285 km/h	Largest since Tip: 2,000 km diameter
Vera	1959	305 km/h	Deadliest Japan typhoon: 5,098 deaths

🌀

Tropical Cyclone

Indian Ocean & South Pacific

Regions

Bay of Bengal: Pre-monsoon (Apr-May) + Post-monsoon (Oct-Nov)
Arabian Sea: Same seasons, less frequent
South Pacific: Nov-Apr (Southern Hemisphere)
Australia: Nov-Apr cyclone season

Bay of Bengal - Deadliest Region

Shallow bay + low-lying Bangladesh = catastrophic storm surge. 1970 Bhola cyclone killed 300,000-500,000. 1991 Bangladesh cyclone: 138,000.

🌊 Why Storm Surge is Deadliest Element ▼

Storm Surge Formation

Wind setup: Hurricane winds push water toward shore. Pressure effect: Low pressure center "lifts" sea surface (1 mb drop = 1 cm rise). Wave action: Waves on top of surge add height. Can reach 6-9 meters above normal tide.

Bangladesh Vulnerability

70% of land <6m above sea level
Dense population in coastal areas (50M+ people)
Funnel shape of Bay of Bengal concentrates surge
Ganges-Brahmaputra delta = flat floodplains
Cyclone shelters now save thousands vs. 1970/1991

Deadliest Surges in History:

1970 Bhola: 10m surge, 500,000 deaths
1991 Bangladesh: 6m surge, 138,000 deaths
2008 Nargis (Myanmar): 5m surge, 138,000 deaths

🦘 Australian Cyclone Characteristics ▼

Northern Australia Season

Season: November to April (Southern Hemisphere summer)
Average: 11 cyclones per season
Region: Queensland, Northern Territory, Western Australia coasts
Category scale: 1-5 (similar to Saffir-Simpson)

Notable Australian Cyclones

Tracy (1974)	Cat 4 - Destroyed Darwin on Christmas Day
Larry (2006)	Cat 5 - $1.5B damage (Queensland)
Yasi (2011)	Cat 5 - One of strongest at landfall
Debbie (2017)	Cat 4 - Severe flooding, $2B+ damage

🌪️

Tornado

Rotating column of air

💨

>400

km/h max

📅

Mar-Jun

Peak (US)

📊

1,200

US/year

Enhanced Fujita Scale

EF0

105-137 km/h • Light

EF1

138-177 km/h • Moderate

EF2

178-217 km/h • Significant

EF3

218-266 km/h • Severe

EF4

267-322 km/h • Devastating

EF5

>322 km/h • Incredible

Tornado Alley

Central US: Cold dry air from Canada meets warm moist air from Gulf of Mexico. Flat terrain allows storms to develop. Texas to Nebraska peak zone.

🔬 How Tornadoes Form ▼

1

Wind Shear: Winds change speed/direction with height, creating horizontal rotation.

2

Updraft Tilts: Thunderstorm updraft tilts horizontal rotation vertical.

3

Mesocyclone: 2-10km wide rotating column forms in supercell.

4

Funnel Descends: Tightening rotation forms condensation funnel.

5

Tornado: Funnel touches ground. Debris cloud confirms contact.

Required Ingredients

Instability: Warm moist air at surface + cold dry air aloft
Wind shear: Changing winds create rotation
Trigger: Front, dryline, or convergence to start updraft
Moisture: Dewpoints >15°C at surface

📊 Extreme Tornado Records ▼

Record	Event	Details
Deadliest Single	Tri-State 1925	695 deaths, 352 km path (MO-IL-IN)
Widest	El Reno 2013	4.2 km wide (Oklahoma)
Fastest Wind	Bridge Creek 1999	486 km/h measured (Oklahoma)
Longest Track	Tri-State 1925	352 km across 3 states
Deadliest Outbreak	April 2011	362 deaths, 360+ tornadoes in 3 days
Most in 24 Hours	April 27, 2011	216 tornadoes
Most Violent	Super Outbreak 1974	148 tornadoes, 30 F4/F5 rated
Costliest	Joplin 2011	$2.8B damage, 158 deaths (EF5)

Only 59 EF5/F5 tornadoes recorded since 1950

Less than 1% of all tornadoes reach EF5 intensity. Last EF5: Moore, Oklahoma (May 20, 2013).

🌍 Tornadoes Around the World ▼

Annual Tornado Count by Country

United States

Peak: Tornado Alley (TX-NE)

~1,200/year

Canada

Alberta to Ontario corridor

~100/year

Bangladesh

Deadliest per capita

~50-100/year

Europe

UK, Netherlands, Germany most

~300-400/year

Australia

Coastal areas

~50/year

Argentina

Pampas region

~50/year

🔥 Surprising Fact

UK has more tornadoes per land area than USA (but much weaker). Netherlands also extremely high density. Most are EF0-EF1.

⛈️

Thunderstorm

Cumulonimbus cloud systems

Types

Single-cell: Ordinary, 30-60 min, weak
Multi-cell: Cluster, longer-lived, stronger
Squall line: Linear, 100s of km, derechos
Supercell: Rotating, severe weather, tornadoes

⚡ Lightning Facts

Temperature: 30,000°C (5x sun surface)
Speed: 300,000 km/h
Global: 8 million strikes/day
Deaths: ~2,000/year worldwide

🔄 Thunderstorm Life Cycle ▼

1

Cumulus Stage: Warm air rises, cloud builds upward. All updraft, no rain yet. Lasts ~10-15 min.

2

Mature Stage: Precipitation starts, creating downdraft alongside updraft. Most intense lightning and rain. Lasts 10-20 min.

3

Dissipating Stage: Downdraft dominates, cuts off updraft. Rain weakens, cloud anvil spreads. Storm dies in 20-30 min.

Why Supercells Live Longer

Normal storms: Downdraft kills updraft. Supercells: Tilted updraft keeps rain/downdraft separate. Storm can last 2-6 hours, travel hundreds of km.

⚡ Lightning Deep Dive ▼

How Lightning Forms

Ice particles collide in cloud, transferring charge
Positive charge accumulates at top, negative at bottom
Ground becomes positively charged by induction
Stepped leader (invisible) descends from cloud
Streamer rises from ground to meet it
Connection made - massive current flows (visible flash)
Multiple return strokes in <1 second

Types of Lightning

Cloud-to-ground (CG): Most dangerous, 25% of all lightning
Intra-cloud (IC): Within same cloud, 75% of lightning
Cloud-to-cloud (CC): Between separate clouds
Positive CG: From cloud top, 10% but most powerful
Ball lightning: Rare, unexplained phenomena

⚡ Lightning Statistics

100×/sec

Global flash rate

1-2 billion

Volts in a flash

30,000 A

Current (avg)

30,000°C

Channel temp

🌪️

Supercell

Rotating thunderstorm

Key Feature: Mesocyclone

Rotating updraft distinguishes supercells. Can persist for hours. Most produce large hail; 25% produce tornadoes.

Structure

Wall cloud: Lowered rotating base
Anvil: Ice-crystal top spreads out
Flanking line: Feeder clouds
Rear-flank downdraft: Wraps tornado

🔬 Supercell Detailed Anatomy ▼

Main Components

MESOCYCLONE

2-10 km wide rotating updraft. Core of supercell. Rotation visible on radar as "hook echo". Wind speeds 40-80 km/h rotation.

UPDRAFT

100-280 km/h vertical winds. Tilted by wind shear, allowing storm to persist. Can punch through tropopause.

FFD

Forward Flank Downdraft. Main precipitation area. Cool air descends, spreads out as gust front.

RFD

Rear Flank Downdraft. Dry air descends behind storm. Wraps around mesocyclone. Tornado often forms here.

ANVIL

Overshooting top + anvil spread. Ice crystals spread downwind at tropopause. Can extend 100+ km from updraft.

Visual Features Storm Chasers Look For

Wall cloud: Lowered rotating base under main storm
Tail cloud: Inflow band feeding into wall cloud
Striations: Horizontal banding showing rotation
Beaver tail: Smooth inflow band (HP supercells)
Clear slot: RFD wrapping around, tornado imminent
Mammatus: Pouch-like clouds on anvil underside

📊 Supercell Classification ▼

Three Main Types

LP Low Precipitation Supercell

Minimal rain, excellent visibility
Dry environment (high plains)
Weak tornadoes but large hail common
Storm chasers love these - easy to photograph

CLASSIC Classic Supercell

Balanced precipitation
Clear structure visible
Most photogenic, distinct wall cloud
Highest tornado probability (30-50%)
Large hail + damaging winds

HP High Precipitation Supercell

Heavy rain wraps around mesocyclone
Tornado often rain-wrapped (invisible)
Most dangerous for storm chasers
Flash flooding + large hail
Common in humid environments (SE US)

💨

Derecho

Widespread straight-line winds

Definition

Long-lived, widespread windstorm from fast-moving thunderstorms. Must have >100 km/h gusts over 400+ km path.

Notable Events

2020 Iowa: $11B damage, widespread crop loss
2012 Ohio Valley: 22 deaths, 4M without power

🔬 How Derechos Form & Sustain ▼

1

Bow Echo Forms: Strong downdrafts hit ground, spread out in arc shape. Visible on radar as bow-shaped line.

2

RIJ Develops: Rear Inflow Jet - descending dry air behind line accelerates winds to 140+ km/h.

3

Self-Sustaining: Gust front lifts warm air, feeding new storms. System races forward at 80-130 km/h.

4

Propagates: Can maintain for 6-12+ hours, traveling 500-1,500+ km.

Required Conditions

Strong mid-level jet stream (steering wind)
Very unstable atmosphere
High dewpoints at surface (moisture)
Dry air aloft to enhance downdrafts
Organized line of storms (squall line/MCS)

💥 Historic Derecho Events ▼

Event	Date	Path	Impact
Iowa Derecho	Aug 10, 2020	1,200 km across IA	$11B damage, 140 km/h winds, 43% of corn crop destroyed
June 2012	Jun 29, 2012	1,100 km (Midwest-Atlantic)	22 deaths, 4M without power, 150 km/h winds
Super Derecho	May 8, 2009	1,600 km (KS-KY)	175 km/h winds, traveled 18 hours
BWER Derecho	Jul 4, 1980	1,100 km	160 km/h+ winds, $600M damage

⚠️ Derecho vs. Tornado Damage

Tornado: Narrow path, rotational damage. Derecho: Wide swath (100s of km), straight-line damage. Trees all fall same direction. Often mistaken for tornado damage.

❄️

Blizzard

Severe snowstorm

Official Criteria (US)

Winds >56 km/h (35 mph)
Visibility <400m (¼ mile)
Duration >3 hours
Heavy or blowing snow

Formation

Low pressure system + cold air mass + moisture source = blizzard. Nor'easters in US East Coast draw moisture from Atlantic.

💨 Ground Blizzard Phenomenon ▼

No Falling Snow Required!

Ground blizzard: Strong winds lift already-fallen snow, creating blizzard conditions without precipitation. Common on Great Plains with dry, powdery snow and strong winds. Can occur days after snowfall under clear skies.

Whiteout Conditions

Zero visibility. Sky and ground indistinguishable. No depth perception. Disorientation common. Drivers can't see hood of car. Accounts for many blizzard deaths - people get lost 10 meters from shelter.

📊 Notorious Blizzards ▼

Event	Date	Impact
Great Blizzard 1888	Mar 11-14, 1888	NE USA: 400 deaths, drifts to 15m, trains buried
Schoolhouse Blizzard	Jan 12, 1888	Great Plains: 235 deaths (many children trapped in schools)
1993 Storm of Century	Mar 12-15, 1993	E USA: 300 deaths, snow from AL to ME
Chicago Blizzard	Jan 26-27, 1967	58 cm snow, 60 km/h winds, 26 deaths, city paralyzed
Buffalo 2014	Nov 17-21, 2014	Lake effect: 170 cm in 4 days, roofs collapsed
Iran Blizzard 1972	Feb 3-9, 1972	Deadliest ever: 4,000 deaths, villages buried under 8m

🧊

Ice Storm

Freezing rain accumulation

Formation

Rain falls through warm layer, then thin freezing layer at surface. Freezes on contact. Different from sleet (freezes before hitting ground).

Hazards

Power lines collapse under ice weight
Trees snap from ice load
Roads become impassable
1998 North America: $4B damage

🌡️ Required Temperature Profile ▼

1

Above freezing aloft (>0°C): Precipitation falls as rain from cloud.

2

Warm layer (>0°C): Rain stays liquid through this layer (100-300m thick).

3

Shallow freezing layer (<0°C): Too thin to freeze drops, but surface is frozen.

4

Supercooled rain hits surface: Instantly freezes into ice coating (glaze).

Why It's Different from Sleet

Freezing Rain (Ice Storm):

Thin freezing layer → liquid hits surface → smooth ice coating

Sleet:

Thick freezing layer → drops freeze before landing → ice pellets bounce

💥 Catastrophic Ice Storm Events ▼

Event	Date	Ice Thickness	Impact
1998 North America	Jan 4-10, 1998	Up to 10 cm	35 deaths, 4M without power for weeks, $4-6B damage
2009 Kentucky/Arkansas	Jan 26-28, 2009	5-8 cm	65 deaths, 1.3M without power, $300M damage
2021 Texas	Feb 13-17, 2021	2-4 cm	246 deaths (mostly hypothermia), grid collapse, $200B+
2013 Toronto	Dec 20-22, 2013	3-5 cm	30,000 trees damaged, 300,000 without power

Weight of Ice

1 cm ice: Adds ~100 kg to power lines
2.5 cm ice: Medium tree branch breaks
5 cm ice: Large branches/whole trees fail
7.5+ cm ice: Catastrophic - steel transmission towers collapse

🌪️

Haboob / Dust Storm

Wall of dust and sand

Formation

Thunderstorm downdraft hits ground and spreads out, picking up dust. Wall can reach 1,500m high, travel 100 km/h.

Locations

Sahara: Largest source of dust globally
Arizona: "Haboob" from Arabic origin
Middle East: Shamal winds carry dust
Australia: Red dust from outback

🌪️ Types of Dust Phenomena ▼

Haboob (Wall of Dust)

Caused by thunderstorm outflow
Massive wall 500-1,500m high
100+ km wide front
Advances at 50-100 km/h
Visibility drops to zero instantly
Lasts 10-30 minutes

Dust Devil

Small rotating column, fair weather
Caused by surface heating
10-100m tall, 1-10m wide
Weak winds (<70 km/h usually)
Lasts seconds to minutes
Harmless (rarely causes damage)

Dust Bowl / Dust Storm

Regional scale, multi-day event
Caused by drought + strong winds
Can affect entire states/countries
Agriculture collapse
Example: 1930s Dust Bowl (US Great Plains)

🌍 Saharan Dust - Global Impact ▼

Largest Dust Source on Earth

Sahara Desert generates 1-3 billion tons of dust annually. Trade winds carry plumes across Atlantic Ocean to Americas. Dust visible from space.

Where It Goes

Amazon Rainforest: 27 million tons/year fertilizes soil (phosphorus)
Caribbean: Affects air quality, stunning sunsets
Southern US: Hazy skies, "Saharan Air Layer"
Mediterranean: "Calima" in Spain

Climate Effects

Suppresses Atlantic hurricane formation
Reflects sunlight, cooling effect
Nutrients feed ocean phytoplankton
Respiratory health impacts downwind

🌨️

Nor'easter

US East Coast winter storm

Characteristics

Northeast winds (hence "nor'easter")
Forms along Gulf Stream boundary
Can bring 30-60cm+ snow
Coastal flooding from storm surge
Peak season: Oct-Apr

Notable Storms

1978 Blizzard: 70cm snow, 99 deaths
1993 "Storm of Century": 300 deaths
2016 Jonas: 60cm in NYC

🔬 Nor'easter Development Process ▼

1

Temperature Contrast: Cold air over land meets warm Gulf Stream water (10-15°C difference).

2

Low Pressure Forms: Off Carolina coast where gradient is strongest. Rapid deepening begins.

3

Jet Stream Involvement: Upper-level winds enhance development. Low intensifies as it moves northeast.

4

Counterclockwise Flow: Brings NE winds onshore. Moisture from ocean = heavy snow/rain.

Miller Classification

Miller Type A: Forms off coast, moves north
Miller Type B: Inland low transfers energy to coastal low
Type B often most intense - "bomb cyclones"

❄️ Legendary Nor'easters ▼

Storm	Date	Snowfall	Impact
Great Blizzard of '78	Feb 5-7, 1978	70 cm Boston	99 deaths, 10,000 cars abandoned, state shut down 1 week
Storm of the Century	Mar 12-15, 1993	140 cm mountains	300 deaths, affected 26 states, $6B damage
Snowmageddon	Feb 5-6, 2010	90 cm Washington DC	Federal gov closed 4 days, record DC snow
Blizzard of '96	Jan 6-8, 1996	76 cm Philadelphia	187 deaths, paralyzed East Coast
Jonas	Jan 22-24, 2016	60 cm NYC	55 deaths, $3B damage
Nemo	Feb 8-9, 2013	102 cm CT	Power out for 350,000, travel ban MA

🌊

Waterspout

Tornado over water

Types

Tornadic: Actual tornado over water, dangerous
Fair-weather: Forms from surface up, weaker

Hotspots

Florida Keys: 400-500/year. Great Lakes in autumn. Mediterranean Sea. Usually <80 km/h but can strengthen if moving onshore.

🌊 Two Completely Different Phenomena ▼

FAIR-WEATHER 95% of waterspouts

Forms on calm, sunny days
Starts at water surface, builds upward
Weak rotation (<80 km/h)
Transparent except for spray at base
Last 2-20 minutes
Not from thunderstorms
Rarely dangerous unless direct hit on boat

TORNADIC 5% of waterspouts

Actual tornado that moved over water
Or tornado that formed over water from severe storm
Descends from storm cloud
Violent winds (>150 km/h possible)
Can move onshore and cause damage
Associated with supercells/severe weather
Extremely dangerous

💣

Bomb Cyclone

Explosive cyclogenesis

Definition

Rapid intensification: pressure drops >24 mb in 24 hours. Creates hurricane-force winds in extratropical storms.

Where They Form

Northwest Atlantic (US East Coast)
Northwest Pacific (Japan)
Where cold continental air meets warm ocean

💥 Explosive Intensification Science ▼

Why "Bomb"?

Term from Sanders & Gyakum (1980). Meteorologically: "Explosive cyclogenesis". Criterion: Pressure fall ≥ 24 mb/24 hours (adjusted for latitude). Some drop 50+ mb in 24h.

Required Ingredients

Baroclinicity: Strong temperature gradient (cold land/warm ocean)
Upper divergence: Jet stream divergence aloft "sucks" air up
Latent heat: Condensation releases energy
Positive feedback: Falling pressure → more convergence → more rising → lower pressure

Typical Pressure Evolution

Hour 0 (start): 1000 mb

Hour 12: 988 mb (-12 mb)

Hour 24: 976 mb (-24 mb) = BOMB

Hour 36: 962 mb (-38 mb total)

💣 Historic Bomb Cyclones ▼

Event	Date	Pressure Drop	Impact
Braer Storm	Jan 10, 1993	914 mb (record)	Strongest extratropical low ever measured
January 2018	Jan 3-4, 2018	59 mb / 24h	US East Coast: 22 deaths, "bombogenesis" trending
Eunice	Feb 18, 2022	40 mb / 24h	UK: 196 km/h winds, 14 deaths, red warning
October 2021	Oct 24, 2021	36 mb / 24h	California: Atmospheric river, 15+ inches rain
December 2022	Dec 21-23, 2022	32 mb / 24h	Blizzard + Arctic blast: 50+ deaths, -45°C wind chills

🧊

Hailstorm

Ice precipitation from thunderstorms

Hail Formation

Strong updrafts carry raindrops above freezing level. Ice grows in layers as stone cycles up and down. Falls when too heavy for updraft.

Size Records

Largest: 20cm diameter (South Dakota, 2010)
Heaviest: 1.02 kg (Bangladesh, 1986)
Golf ball size (4.4cm) causes significant damage

Damage

$10-15 billion/year in US alone. Destroys crops, vehicles, roofs. "Hail Alley" from Texas to Nebraska most affected.

🔬 How Hailstones Grow ▼

1

Raindrop Carried Up: Updraft lifts water droplet above freezing level (>5,000m). Freezes into tiny ice pellet.

2

Cycling: Falls, picks up supercooled water, rises again. Each cycle adds ice layer (like an onion).

3

Growth Zones: Clear ice forms in wet zones. Opaque ice in dry/cold zones. Alternating layers visible when cut.

4

Falls: When too heavy for updraft (80-160+ km/h updraft needed for giant hail).

Updraft Strength Required

Pea size (0.6 cm): 40 km/h updraft

Golf ball (4.4 cm): 80 km/h updraft

Baseball (7 cm): 120 km/h updraft

Softball (10+ cm): 160+ km/h updraft

📊 Extreme Hail Events ▼

Record	Location	Date	Details
Largest Diameter	Vivian, SD	Jul 23, 2010	20.3 cm (8 inches) - volleyball size
Heaviest	Bangladesh	Apr 14, 1986	1.02 kg - killed 92 people
Costliest (single event)	Munich, Germany	Jul 12, 1984	$2B damage (70,000 buildings)
Deadliest Modern	Moradabad, India	Apr 30, 1888	246 deaths
Costliest US	Dallas, TX	Apr 2024	$2+ billion in auto/property damage

Hail Alley - Most Active Region

Wyoming-Nebraska-Colorado triangle: Most hail days per year globally. High elevation + strong jet stream + dry air = perfect conditions. Cheyenne, WY averages 9-10 hail days/year.

🌧️

Monsoon

Seasonal wind reversal

Asian Monsoon

Summer (SW): Wet, Jun-Sep, from Indian Ocean
Winter (NE): Dry, Nov-Feb, from Siberia
80% of India's annual rainfall in 4 months
Feeds 1.5 billion people

Other Monsoons

West African: Jun-Sep, brings Sahel rains
Australian: Dec-Mar, northern Australia
North American: Jul-Sep, Arizona/Mexico

🔬 How Monsoons Work ▼

Summer Monsoon (Wet Season)

1

Land Heats: Continent (Asia) heats faster than ocean in summer. Warm air rises over land.

2

Low Pressure: Rising air creates low pressure over land. High pressure over relatively cooler ocean.

3

Winds Reverse: Moist ocean air flows toward land low. Crosses equator, Coriolis deflects to SW winds (India).

4

Heavy Rain: Moist air rises over land/mountains. Condenses = monsoon rains Jun-Sep.

Winter Monsoon (Dry Season)

1

Land Cools: Continent cools faster than ocean in winter. High pressure over cold Siberia.

2

Winds Reverse Again: Dry air flows from land to ocean. NE winds dominate (dry, from land).

3

Dry Season: Little moisture = minimal rain Nov-Feb. Clear skies, pleasant weather.

📊 Monsoon Failures & Extremes ▼

⚠️ Impact of Monsoon Failure

Weak monsoon = drought = crop failure = famine. Over 1 billion people depend on monsoon for agriculture, drinking water, hydropower. India's GDP fluctuates 2-3% based on monsoon strength.

What Affects Monsoon Strength?

El Niño: Weakens Indian monsoon (warm Pacific suppresses rainfall)
La Niña: Strengthens monsoon (cool Pacific enhances convection)
Indian Ocean Dipole: Positive = strong monsoon, Negative = weak
Snow cover: Heavy Himalayan snow = cooler land = weaker monsoon
Climate change: Increasing variability (stronger extremes)

Extreme Rainfall Records

Cherrapunji, India: 26,471 mm/year (wettest place debate)
Mawsynram, India: 11,872 mm/year average (26 km from Cherrapunji)
2013 Uttarakhand floods: 340 mm in 24h, 5,700 deaths
2005 Mumbai: 944 mm in 24h, city paralyzed

🔴 Currently Active

⛈️ Complete Storm Type Database

Hurricane

Formation Requirements

Saffir-Simpson Scale

Energy Source

⚠️ 2005 Atlantic Season - Record Breaker

⚠️ Quick Records

Typhoon

Same as Hurricane, Different Name

Super Typhoons (Cat 4-5 equivalent)

Perfect Conditions Year-Round

Annual Statistics

Tropical Cyclone

Regions

Bay of Bengal - Deadliest Region

Storm Surge Formation

Bangladesh Vulnerability

Northern Australia Season

Notable Australian Cyclones

Tornado

Enhanced Fujita Scale

Tornado Alley

Required Ingredients

Annual Tornado Count by Country

🔥 Surprising Fact

Thunderstorm

Types

⚡ Lightning Facts

Why Supercells Live Longer

How Lightning Forms

Types of Lightning

⚡ Lightning Statistics

Supercell

Key Feature: Mesocyclone

Structure

Main Components

Visual Features Storm Chasers Look For

Three Main Types

Derecho

Definition

Notable Events

Required Conditions

Blizzard

Official Criteria (US)

Formation

No Falling Snow Required!

Whiteout Conditions

Ice Storm

Formation

Hazards

Why It's Different from Sleet

Weight of Ice

Haboob / Dust Storm

Formation

Locations

Largest Dust Source on Earth

Where It Goes

Climate Effects

Nor'easter

Characteristics

Notable Storms

Miller Classification

Waterspout

Types

Hotspots

Bomb Cyclone

Definition

Where They Form

Why "Bomb"?

Required Ingredients

Typical Pressure Evolution

Hailstorm

Hail Formation

Size Records

Damage

Updraft Strength Required

Hail Alley - Most Active Region

Monsoon

Asian Monsoon