What Is the Predictability Limit of Midlatitude Weather?
Abstract
Understanding the predictability limit of day-to-day weather phenomena such as midlatitude winter storms and summer monsoonal rainstorms is crucial to numerical weather prediction (NWP). This predictability limit is studied using unprecedented high-resolution global models with ensemble experiments of the European Centre for Medium-Range Weather Forecasts (ECMWF; 9-km operational model) and identical-twin experiments of the U.S. Next-Generation Global Prediction System (NGGPS; 3 km). Results suggest that the predictability limit for midlatitude weather may indeed exist and is intrinsic to the underlying dynamical system and instabilities even if the forecast model and the initial conditions are nearly perfect. Currently, a skillful forecast lead time of midlatitude instantaneous weather is around 10 days, which serves as the practical predictability limit. Reducing the current-day initial-condition uncertainty by an order of magnitude extends the deterministic forecast lead times of day-to-day weather by up to 5 days, with much less scope for improving prediction of small-scale phenomena like thunderstorms. Achieving this additional predictability limit can have enormous socioeconomic benefits but requires coordinated efforts by the entire community to design better numerical weather models, to improve observations, and to make better use of observations with advanced data assimilation and computing techniques.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 01, 2019
- Source ID
- 10.1175/jas-d-18-0269.1
Entities
People
- Fuqing Zhang
- Jan-huey Chen
- Kerry Emanuel
- Linus Magnusson
- Roberto Buizza
- Shian-jiann Lin
- Y. Qiang Sun
Organizations
- Directorate for Geosciences
- European Centre for Medium-Range Weather Forecasts
- Massachusetts Institute of Technology
- National Oceanic and Atmospheric Administration
- National Science Foundation
- Office of Naval Research
- Pennsylvania State University