The atmospheric ‘cold blob’ over Fennoscandia from October 2023 to January 2024

Abstract

Between October 2023 and January 2024, a remarkably persistent cold air anomaly prevailed over Fennoscandia on an otherwise record-warm planet. This article describes the temperature anomalies, atmospheric circulation and seasonal predictions associated with the cold blob. The 4-month period from October to January was the third coldest in Fennoscandia during the ongoing century. The cold blob was associated with anomalous atmospheric circulation; for example, jet stream wind speeds were exceptionally high south of Fennoscandia. Furthermore, seasonal forecasts failed to capture the cold blob, which may be related to difficulties in simulating El Niño teleconnections by long-range forecasting systems.