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STEPS: A probabilistic precipitation forecasting scheme which merges an extrapolation nowcast with downscaled NWP
Author(s) -
Bowler Neill E.,
Pierce Clive E.,
Seed Alan W.
Publication year - 2006
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1256/qj.04.100
Subject(s) - quantitative precipitation forecast , extrapolation , numerical weather prediction , probabilistic logic , precipitation , meteorology , probabilistic forecasting , probability density function , environmental science , nowcasting , quantitative precipitation estimation , global forecast system , ensemble forecasting , computer science , mathematics , statistics , geography , artificial intelligence
An ensemble‐based probabilistic precipitation forecasting scheme has been developed that blends an extrapolation nowcast with a downscaled NWP forecast, known as STEPS: Short‐Term Ensemble Prediction System. The uncertainties in the motion and evolution of radar‐inferred precipitation fields are quantified, and the uncertainty in the evolution of the precipitation pattern is shown to be the more important. The use of ensembles allows the scheme to be used for applications that require forecasts of the probability density function of areal and temporal averages of precipitation, such as fluvial flood forecasting—a capability that has not been provided by previous probabilistic precipitation nowcast schemes. The output from a NWP forecast model is downscaled so that the small scales not represented accurately by the model are injected into the forecast using stochastic noise. This allows the scheme to better represent the distribution of precipitation rate at spatial scales finer than those adequately resolved by operational NWP. The performance of the scheme has been assessed over the month of March 2003. Performance evaluation statistics show that the scheme possesses predictive skill at lead times in excess of six hours. © Crown copyright, 2006.