Details

Autor(en) / Beteiligte

• Oertel, A.
• Pickl, M.
• Quinting, J. F.
• Hauser, S.
• Wandel, J.
• Magnusson, L.
• Balmaseda, M.
• Vitart, F.
• Grams, C. M.

Titel

Everything Hits at Once: How Remote Rainfall Matters for the Prediction of the 2021 North American Heat Wave

Ist Teil von

• Geophysical research letters, 2023-02, Vol.50 (3), p.n/a

Ort / Verlag

Washington: John Wiley & Sons, Inc

Erscheinungsjahr

2023

Link zum Volltext

Quelle

Wiley Online Library Journals Frontfile Complete

Beschreibungen/Notizen

• In June 2021, Western North America experienced an intense heat wave with unprecedented temperatures and far‐reaching socio‐economic consequences. Anomalous rainfall in the West Pacific triggers a cascade of weather events across the Pacific, which build up a high‐amplitude ridge over Canada and ultimately lead to the heat wave. We show that the response of the jet stream to diabatically enhanced ascending motion in extratropical cyclones represents a predictability barrier with regard to the heat wave magnitude. Therefore, probabilistic weather forecasts are only able to predict the extremity of the heat wave once the complex cascade of weather events is captured. Our results highlight the key role of the sequence of individual weather events in limiting the predictability of this extreme event. We therefore conclude that it is not sufficient to consider such rare events in isolation but it is essential to account for the whole cascade over different spatiotemporal scales. Plain Language Summary In June 2021, Western North America experienced an intense heat wave with unprecedented temperatures and far‐reaching socio‐economic consequences. We show that the forecast of the extreme temperature anomalies was limited due to a complex sequence of weather events across the Pacific. Thus, state‐of‐the‐art weather forecasts were only able to predict the magnitude of the heat wave once the cascade of weather events was captured in the forecast. Key Points Intense 2021 North American heat wave is associated with extremely amplified upper‐level ridge Magnitude of record‐high temperatures was not predicted beyond 7 days Chain of synoptic‐scale precipitation events constitutes predictability barrier