Prediction of Storm Hazards (AQA A Level Geography)

• One of the most common measures of a tropical storm’s intensity is the five-point Saffir-Simpson scale which is based on wind speeds
• It rates storms from Category 1 (weakest) to Category 5 (strongest)
• Tropical storms are considered major when they reach category 3 and have wind speeds between 111-129 miles (178-208 kilometres) per hour
• A category 5 storm can deliver wind speeds of more than 157 miles (252km) an hour

Saffir-Simpson 5-Point Scale of Wind Strength

Category	Wind Speeds	Damage
1	74-95 mph 119-153 km/h	Some
2	96-100 mph 154-177 km/h	Extensive
3	111-129 mph 178-208 km/h	Devastating
4	130-156 mph 209-251 km/h	Catastrophic
5	157 mph or higher 252 km/h	Catastrophic

• Tropical storms are relatively frequent in many parts of the world, but the frequency can vary significantly from year to year
• On average, there are about 80 tropical storms each year
• The highest number of tropical storms form over the Pacific Ocean (on average over 50 per year)
• In the Atlantic Basin (which includes the Caribbean Sea and the Gulf of Mexico) an average of 12 tropical storms form each season, with around 6 of these becoming hurricanes
• Tropical storms tend to occur during tropical storm season
• In the Northern Hemisphere, this runs from June to November, with the peak months falling in August, September and October
• In the Southern Hemisphere, the season runs from November to April, with peak months falling in January, February and March
• It can be useful that most storms occur at particular times of year in terms of preparation and monitoring

Tropical storm season in the Atlantic Basin

• Prediction of tropical storms involves gathering data from a wide range of sources such as satellites, weather balloons, radar and ocean buoys
• The data includes atmospheric pressure, wind speed and direction, humidity, sea surface temperatures and ocean currents
• The data is fed into computer models that simulate the behaviour of the atmosphere and ocean to help predict the likely path and intensity of the storm
• Although these models are sophisticated, uncertainties remain and predictions are not always accurate and precise, especially over the longer term
• The path of a tropical storm can be erratic, so landfall is not easy to predict accurately and precisely in advance
• Every year, the NOAA (US National Oceanographic and Atmospheric Administration) releases long-term predictions of tropical storm activity for the coming season
• This is based on historical data as well as current and projected climate conditions such as ocean temperatures and atmospheric conditions

Atlantic hurricane season outlook for 2022