Prediction and Warnings

Prediction

Due to recent advances in weather prediction computer models, forecasting the initial development of tropical cyclones has improved greatly over the last couple of decades.

There are certain areas over the oceans that are particularly favourable for tropical cyclone development, but it is usually certain characteristics in a cluster of thunderclouds that leads forecasters to recognise them as tropical depressions. This is done by people at specialist tropical cyclone forecasting centres around the globe such as the National Hurricane Center and National Hurricane Center & Central Pacific Hurricane Center who are constantly studying satellite images, instruments and other weather data to detect and track them through their life-cycle. Once detected, their track is forecast using a combination of computer forecasting models, synoptic forecasting and statistical methods, which have been developed from the study of the behaviour of past storms.

Observations from ships at sea are always very useful, although understandably once the existence of a storm and its forecast track have been broadcast; ships tend to move out of their way. Reinforced aircraft, fitted with instruments, can fly through and over tropical cyclones, and weather radar can locate storms within 200 miles of the radar station. In addition, tropical cyclones are tracked by satellites, which provide very useful information both to forecasters and numerical forecast models.

Warnings

The USA has the most sophisticated tropical cyclone warning systems. Once a tropical depression has been identified, a series of forecast advisories, which detail the expected track and likely strength of the tropical cyclone, is broadcast. When there are definite indications that a tropical cyclone is approaching land, watches and warnings along coastal regions are raised, which aim to give information to the local authorities of places likely to be in the tropical cyclone's path, so that they can make preparations to protect public safety.

Specially designed shelters in which people can ride out the worst of the weather may have been built in many areas such as Florida. Coastal regions immediately in a tropical cyclone's path are particularly dangerous and people are usually advised to move away from these. In the USA, this can involve the mass evacuation of a million or more people. Warnings are broadcast on TV and radio. NOAA Weather radio is available on a variety of frequencies and gives up-to-date information and advice. There is also a lot of information on a variety of web sites, the most authoritative being those maintained by NOAA and the National Hurricane Center.