Abstract ID: 225
The potential for using weather patterns to advance sub-seasonal forecasting in Southeast Asia
Lead Author: Steven Woolnough
National Centre for Atmopsheric Science, University of Reading, United Kingdom
Keywords: Weather Patterns, Southeast Asia, Precipitation, Subseasonal Forecasting
Abstract: Early warning of high of impact weather (HIW) events can enable agencies and individuals to take action to mitigate the impact of those events. However high impact weather events, particularly those associated with precipitation can be difficult to predict at long lead times due to their dependence on convective scale processes. However, the large-scale circulation in which those weather events are embedded should be more predictable at longer timescales, and with knowledge about how the likelihood of HIW depends on the large-scale circulation prediction of the large-scale can be used to provide information about the likelihood of HIW.
We derive and compare two sets of weather patterns for Southeast Asia based on the 850hPa wind field with and without imposing a separation between the planetary-scale and regional-scale circulation. We show the relationship between these weather patterns and the seasonal cycle and known modes of tropical circulation variability on the planetary scale, such as ENSO and the MJO, synoptic scale features such as cold surges and tropical cyclones. We further explore the potential to use these weather patterns to describe variations in the mean precipitation and the likelihood of heavy precipitation. Observed relationships between the weather patterns and HIW are used to develop a hybrid dynamical-statistical forecast for HIW in Southeast Asia and the skill of these forecasts is assessed and compared to direct forecasts of HIW from the Met Office GloSEA5 sub-seasonal hindcasts. This comparison reveals a small, but significant, gain in forecast skill when using the pattern-conditioned forecasts.
Co-authors:
Emma Howard (National Centre for Atmospheric Science, University of Reading)
Paula Gonzalez (National Centre for Atmospheric Science, University of Reading)
Simon Thomas (National Centre for Atmospheric Science, University of Reading)
Gabriel Wolf (Department of Meteorology, University of Reading)
Oscar MartÃnez-Alvarado (National Centre for Atmospheric Science, University of Reading)
John Methven (Department of Meteorology, University of Reading)
Tom Frame (Department of Meteorology, University of Reading)
Chris Holloway (Department of Meteorology, University of Reading)
