At short time ranges a higher level of detail can be forecast with more reliability. The forecasting of the weather in the 0- to 6-hour time frame is often referred to as nowcasting
Traditionally, numerical computer models have been poor at forecasting thunderstorms and other small-scale details. Therefore, the human forecaster has had an advantage over computer NWP models when it comes to forecasting small- (meso-) scale features. The forecaster is able to compare a model field against actual observations and respond quickly and amend a forecast, should the situation warrant it. Rainfall radar observations are very useful in this time frame, and post-processing is used to make very short-range predictions.
More than six hours ahead, numerical model forecasts gain an advantage over other forecasting techniques. Ongoing research at the Met Office, to develop the next generation high-resolution numerical weather prediction system over the UK, should eventually allow numerical model forecasts to become the dominant nowcasting tool as the model's ability to forecast thunderstorms and small-scale features dramatically improves.
National Severe Weather Warning Service
The Met Office has a responsibility to provide warnings of severe weather under the National Severe Weather Warning Service. Nowcasting is used to decide when a Flash warning, which indicates a high confidence of severe weather occurring in the next few hours, needs to be issued. Many forecasts are provided to our customers in this time range.
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