Fruitful discussions with C. Bishop, E. Kalnay, J. Anderson, I. Szyunogh, P. Houtekamer, F. Zhang, G. Compo, H. Mitchell, and B. Hunt are gratefully acknowledged, as are the comments of three anonymous reviewers. This project would not have been possible without the support of the NOAA THORPEX program, which partially funded this research through a grant, and NOAA’s Forecast Systems Laboratory, which provided access to their High Performance Computing System. TMH was partially supported through National Science Foundation Grants ATM-0130154 and ATM-020561.
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