Persistence
Persistence forecasting is based on the concept that current weather conditions can reveal clues to tomorrow's forecast. Meteorologists who rely on this forecasting method predict that current conditions will persist, or continue unchanged. They make observations using thermometers and barometers to assess the weather, then theorize that the next few days will feature similar weather patterns. This forecasting technique works best in areas with predictable weather patterns, such as a tropical zone or an arctic region.
Synoptic
Synoptic, or analogue forecasting is a method of predicting the weather based on accepted theories and principles of meteorology. This technique requires some skill and training, and incorporates weather maps, radar and satellite images. Forecasters combine these tools with information about atmospheric pressure, air flow and temperatures to come up with a forecast. Synoptic forecasting served as the primary method of predicting the weather through the 1950s and '60s. It's still used today for short term predictions.
Statistical
Statistical or climatological forecasting allows meteorologists to make predictions based on historical trends. It assumes consistent weather patterns over time. Forecasters examine historical information about average, high and low temperatures to estimate future temperature ranges. They also examine historical storm records and precipitation amounts and use those as a basis for forecasting. For example, a statistical forecaster may state that the next month will bring rain and cold temperatures because that is considered the normal condition for this area at this time of year.
Computer Modeling
Computer modeling forecasts represent the most advanced method of predicting the weather. This method relies on mathematical formulas that are designed to model atmospheric and weather conditions. By inputting current weather data, the meteorologist can calculate future conditions. Top weather-related agencies, such as the National Weather Service and National Hurricane Center, rely on this form of forecasting to maximize accuracy.