Which Sudden Stratospheric Warming Events Are Most Predictable?

Area of Science:

• Atmospheric Science
• Climate Dynamics
• Meteorology

Background:

• Sudden Stratospheric Warming (SSW) events are significant atmospheric phenomena with far-reaching impacts.
• Understanding and predicting SSW events is crucial for seasonal forecasting.

Purpose of the Study:

• To assess the predictability of Northern Hemisphere SSW events using multiple subseasonal to seasonal (S2S) forecast models.
• To identify key precursor factors that influence SSW predictability.

Main Methods:

• Analysis of 16 major SSW events since 1998.
• Evaluation of 10 subseasonal to seasonal (S2S) forecast models.
• Identification of four key factors distinguishing predictable SSWs.

Main Results:

• A preconditioned vortex, active Madden-Julian Oscillation (MJO), specific Quasi-Biennial Oscillation (QBO) phase, and vortex morphology are key predictors.
• These factors collectively explain 40% of the variability in SSW predictability.
• Some identified factors have not been previously explored in large-sample SSW studies.

Conclusions:

• SSW predictability is significantly enhanced by favorable precursor conditions.
• While individual factors may not reach 95% statistical significance due to sample size, their combined effect is substantial.
• Future research should incorporate these identified precursors for improved SSW forecasting.