Operational applications of ensemble prediction in the Southern Hemisphere

s. Over the past few years ensemble prediction has come to the fore as a major element in numerical prediction and operational weather forecasting. This stems from convergence of increasing recognition of the importance of explicitly addressing the intrinsic uncertainties in forecasts with adequate computer resources and development of ensemble strategies sufficient to address the problem. The net result of this convergence is an expanding capability to provide quantitative estimates of those uncertainties, which vary from day to day, by region, parameter, and circulation regime. It is widely agreed that ensemble based probabilities and/or measures of confidence hold the best potential for enhancing the ability to make user dependent informed decisions.

The National Centers for Environmental Prediction (NCEP) currently runs a 17 member ensemble with its global Medium Range Forecast (MRF) model for medium-range (3-14 days) prediction. It is also developing a system and strategies for short-range (0-3 days), regional-model based (Eta, RSM) ensembles. In this paper we briefly describe some of the basic questions, problems, issues, etc. with regard to ensemble prediction; however, focus primarily is on the use of ensemble based products and their applications to various forecast problems particularly relevant to Southern Hemisphere meteorology. Case studies and verification statistics are used to demonstrate the result