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Which Stratospheric Sudden Warming Events are Most Predictable?
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  • Dvir Chwat,
  • Chaim I Garfinkel,
  • Wen Chen,
  • Jian Rao
Dvir Chwat
Hebrew University of Jerusalem
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Chaim I Garfinkel
Hebrew University of Jerusalem

Corresponding Author:[email protected]

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Wen Chen
Institute of Atmospheric Physics, Chinese Academy of Sciences
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Jian Rao
Nanjing University of Information Science and Technology
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The predictability of stratospheric sudden warming (SSW) events are considered in 10 subseasonal to seasonal (S2S) forecast models for 10 SSWs over the period 1999-2009. The 10 SSWs are divided into those with above-average predictability (in one case exceeding 20 days), below-average predictability, and average predictability. The four factors that most succinctly distinguish the composite with above average predictability are an active Madden-Julian Oscillation with enhanced convection in the West Pacific, the Quasi-Biennial Oscillation phase with easterlies in the lower stratosphere, a strong SSW, and a strong pulse of wave activity in the week before the event. Other factors, such as El Nino, stratospheric preconditioning, and the morphology (split vs. displacement) are comparatively less important.