Severe Weather Overview

Severe weather can significantly damage buildings, disrupt infrastructure, and endanger lives.
Different kinds of severe weather include:
  - Blizzards
  - Heat waves
  - Severe thunderstorms
  - Tornadoes
  - Hurricanes
  - Droughts
  - Ice storms
Additional dangers from severe weather:
  - Wildfires
  - Landslides
  - Flash floods
Local weather patterns dictate the specific types of severe weather to prepare for.
Historical maps reveal patterns that predict future severe weather occurrence.
Course Goals:
- Understand five types of severe weather, their causes, impacts, and safety measures.
- Learn about weather forecasting methodologies using satellite and radar imagery.

Definition: A blizzard is a severe winter storm characterized by:
  - Winds greater than 56 km/h (34.7 mph)
  - Poor visibility due to blowing snow
  - Lasting at least three hours.
Dangers of Blizzard Conditions:
  - Extreme cold leading to frostbite and hypothermia
    - Hypothermia occurs at body temperature below 35°C (95°F).
  - Snow accumulation can block roads and cause power outages.
Formation of Blizzards:
- Occurs when a low-pressure system develops where moist, warm air rises over cold air, producing heavy snowfall and high winds.
Prediction and Monitoring:
- National Weather Service (NWS) utilizes satellite images, weather data, and historical data to forecast blizzards, particularly in the Midwest, Northeast, and mountainous areas.
Evidence from Satellite Imagery:
- Satellite images, like those from NOAA’s GOES-16, are critical in weather predictions, as they show current conditions that may lead to blizzard warnings.

Definition: A heat wave is defined as a prolonged period of excessively hot weather, often accompanied by high humidity, lasting at least two days.
Dangers of Heat Waves:
  - Particularly hazardous for vulnerable populations: elderly, infants, and those without air conditioning.
  - Risk of heatstroke when body temperature exceeds 41°C (106°F) without prompt treatment.
  - Increased risk of wildfires during heat waves.
Heat Index:
- Metric combining humidity and temperature to indicate how hot it feels. e.g., at 75% humidity and 32°C (90°F), the heat index is 43°C (109°F).
Prediction of Heat Waves:
- Forecasters analyze temperature trends and rising humidity signals in stationary high-pressure systems.
Mitigation Strategies:
- Use of air conditioning, public cooling centers, and hydration to avoid heat-related illnesses during predicted heat events.

Definition: A severe thunderstorm is characterized by:
  - Wind speeds exceeding 93 km/h (57.7 mph)
  - Hail at least 2.5 cm (0.98 in.) in diameter
  - Potential tornado development.
Dangers of Severe Thunderstorms:
- Damage from severe wind, hail, flooding, and lightning strikes.
Safe Practices:
- Seek shelter indoors and away from windows or electrical devices during thunderstorms.
- Avoid flooded roads as vehicles can be swept away in water as shallow as 30 cm (1 ft).
Formation Insights:
- Severe thunderstorms form where warm, moist air meets cooler, dry air. A strong updraft of warm air combined with downdrafts allows the storm to grow extensively.
- They often produce hail and tornadoes when strong updrafts separate from downdrafts, extending the storm lifespan.
Prevalence:
- Roughly 10,000 severe thunderstorms occur annually in the United States, particularly in the central region between Texas and Minnesota.

Definition: A tornado is a violent rotating column of air that touches the ground, with wind speeds reaching or exceeding 117 km/h (73 mph).
Damage Characteristics:
- Damage correlates with wind speed; higher winds result in more destruction.
- Consequences include damage to infrastructure, loss of power, and spread of debris.
Frequency:
- Over 1,000 tornadoes occur in the U.S. each year, predominantly in Florida and the area known as Tornado Alley (Texas, Kansas, Oklahoma).
Tracking and Warnings:
- Scientists analyze storm formations, particularly using radar to observe hook echoes and other indicators of tornado development.
- Alerts are disseminated through local sirens and shelter provisions during tornado warnings.
Safety Measures:
- Seek underground shelters when possible or find a safe interior room away from windows and outside walls.

Definition: A hurricane is a large, organized storm that occurs over warm ocean waters, characterized by sustained wind speeds of at least 119 km/h (73.9 mph).
Formative Conditions:
- Require warm sea surface temperature, moist air, and low pressure systems to develop.
- Hurricanes typically rotate counterclockwise in the Northern Hemisphere.
Structure:
- Contain an eye of calm, surrounded by the eyewall where winds are strongest. Rainbands extend from the eyewall.
Forecasting and Tracking:
- Satellites monitor hurricanes, and forecasts are generated to predict paths and potential landfall.
- Hurricane season in the North Atlantic lasts from June to November, averaging six formations annually.
Storm Surge:
- A significant rise in ocean water that can lead to severe flooding along coastal areas, sometimes up to 6 meters high, especially during landfall.

Forecast Challenges:
- Current tornado warnings often issued less than 13 minutes before a tornado strikes.
Research and Development:
  - NOAA's National Severe Storms Laboratory works on advanced computer modeling systems that can provide alerts 30 to 60 minutes ahead.
  - Predictive models require historical data, real-time data, and extensive computational resources for accuracy.
  - Models are tested at the Hazardous Weather Testbed for both effectiveness and usability.

Key Takeaways:
- Understanding severe weather patterns and responses is essential for risk management.
- Preparedness is crucial; having emergency plans based on local weather threats can aid in safety during severe events.