The Canadian Meso4dvar Continental Analysis System: Pre-Operational Evaluations Luc Fillion 1 Collaborators : Monique Tanguay 1 , Zhuo Liu 1 , Ervig Lapalme 2 , Nils Ek 2 , Christian Pagé 3 , Simon Pellerin 1 , 1 Meteorological Research Division, Environment Canada, Dorval, Québec, Can 2 Canadian Meteorological Center, Dorval, Québec, Can 3 Météo-France/CNRM/DPrévi/Aéro, Toulouse, France ABSTRACT We present an update on earlier results presented at the AMS-2006 meeting in Atlanta on the continental regional data assimilation system to be used for operational short-term weather forecasting (up to 2 days) by the Canadian Meteorological Center (CMC). Pre- operational evaluations are currently underway and early results will be presented at the conference. 1. INTRODUCTION At Environment Canada (EC), a Limited- Area 4D-Var analysis system has been developed in order to enable the analysis of synoptic and mesoscale weather. This system is referred to as Meso4dvar. The main objective of this new analysis system being the improved forecast of precipitation up to 48h, with a replacement of the Canadian Regional analysis system currently operational at CMC. Figure 1 shows two types of limited area analysis/forecast domains considered. Corresponding author address: Dr. Luc Fillion, Meteorological Research Division, Environment Canada, 2121 Route Trans-Canadienne, Dorval, Qc, Can, H9P 1J3 email: luc.fillion@ec.gc.ca The large domain is for the “North American Continental” configuration. The Meso4dvar analysis is designed to suit the Limited-Area version of the GEM model (Cote et al. 1998). The latter being used operationally only in global mode with uniform and non- uniform mesh for medium-range and short- range weather forecasting respectively. Tangent-linear (TL) and adjoint (AD) versions of GEM-LAM were developed as an extension of the work by Tanguay and Polavarapu (1999). The TL/AD GEM-LAM code was coupled last year to the limited- area version of the variational analysis code.