Techniques in Forecasting

Most of us are quite well aware of weather forecasting and the role it plays in the modern society. From helping us to plan our travels in a safe manner to saving us from the perils of cyclones and tornadoes, weather forecasting today serves as a valuable guide in our lives.

For the uninitiated, weather forecasting is a method used to predict changes in atmosphere for a particular time and location. Forecasting is accomplished by regular study of the data about the present condition of the atmosphere and then predicting the state of the atmosphere in a future time. Due to the dynamic nature of the atmosphere, weather changes are difficult to foretell and predictions become progressively inaccurate once the duration between the present time and the time for which the forecast is being made increases.

With improvements in techniques and technology, weather forecasting today has noticeably come of age. Some of the key techniques used in weather forecasting are mentioned below: –

Persistence Forecasting

Being the simplest method to forecast weather, persistence relies upon the current conditions to forecast tomorrow’s weather. This method depends upon the distinct weather patterns that are similar every year. It is practical for both long range and short range forecasting.

Barometer – It is an instrument used to measure atmospheric pressure and is being used since the late 19th century. It depends upon the principle that the amount of change in atmospheric pressure is directly proportional to the change that will occur in the weather. Generally, steep pressure drops would mean that one could expect rains and a rise in pressure would indicate that a possibility of the skies clearing up.

Nowcasting – It is a method used to predict weather changes for extremely short ranges, for example, the next six hours. Nowcasting makes it possible to predict individual showers and thunderstorms with great accuracy. With the help of computer model constituting radar, a satellite system and dependable observational data, more accurate predictions can be made of the weather that will be following in the next few hours.

Using Forecast Models – These are based on a number of factors such as model biases and performance. Forecast errors can be reduced using a consensus of forecast models and ensemble members of various types. Human intervention is still required but it wont be so in the near future.

Analog Forecasting – It is also called “pattern recognition”. This is a more time consuming and complex technique where the forecaster has to remember a previous forecasting event, which is going to be mimicked by a current one. Perfect analogs for a future event are very rare making this technique comparatively difficult to employ. This method is useful for observing rainfall over oceans, which are technically referred to as “data voids”, and predicting the precipitation amounts for the future.

Ensemble Forecasting – It is a numerical method of forecasting which is achieved through the generation of many forecasts which in turn explain the uncertain nature of the initial state of the atmosphere. They are best used for operational weather forecasting at places like European Center For Medium Range Weather Forecasts (ECMWF) and The Canadian Forecasting Center etc.

With the advancement in technology, weather forecasting is becoming increasingly accurate but mankind still has a long way to go as there is nothing as unpredictable as the weather.