Factors influencing the seasonal predictability of northern hemisphere severe winter storms

• Published in: Geophysical Research Letters
• Main Authors: Hansen, F, Kruschke, T, Greatbatch, RJ, Weisheimer, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2019
• Subjects: Greenland
• Online Access: https://doi.org/10.1029/2018gl079415; https://ora.ox.ac.uk/objects/uuid:e71f528f-df2e-4e5a-9eb6-8542705c78df

We investigate the role of the tropics, the stratosphere, and atmosphere‐ocean coupling for seasonal forecasts of strong, potentially damaging, Northern Hemisphere extratropical winter wind storm frequencies. This is done by means of relaxation experiments with the European Centre for Medium‐Range Weather Forecasts model, which allow us to prescribe perfect forecasts for specific parts of the coupled atmosphere‐ocean system. We find that perfect predictions of the Northern Hemisphere stratosphere significantly enhance winter storm predictive skill between eastern Greenland and Northern Europe. Correct seasonal predictions of the occurrence of stratospheric sudden warmings play a decisive role. The importance of correctly predicting the tropics and of two‐way atmosphere‐ocean coupling, both for forecasting stratospheric sudden warming risk and, correspondingly, severe winter storm frequency, is noted.