stormregimes

Storm regimes are recurring patterns of extratropical storm activity in a geographic region, defined by typical storm tracks, timing, and associated hazards such as heavy precipitation and strong winds. They arise from large-scale atmospheric circulation, including the jet stream and frontal zones, and are modulated by ocean conditions and teleconnections such as ENSO and the North Atlantic Oscillation.

Researchers identify storm regimes from historical observations and reanalysis data using synoptic climatology, clustering of storm tracks, or pattern analysis of pressure fields. The resulting regimes summarize regional variability and provide a compact description of how storms tend to behave across seasons and years.

Regimes vary by region. In Eurasia and North America, winter often features a dominant westerly Atlantic and Pacific storm track, with occasional blocking that yields cold outbreaks or heavy rain. The Mediterranean exhibits a distinct regime linked to subtropical anticyclones, while the North Pacific regime is shaped by the Aleutian Low and Pacific jet. Teleconnections help explain why regimes shift from year to year.

Applications include weather forecasting, flood and wind risk assessment, hydrological planning, and climate impact studies. Recognizing regime tendencies supports anticipation of seasonal risks and aids in planning under climate variability and change, albeit with uncertainty due to natural variability and methodological choices.

Limitations include dependence on data quality, spatial and temporal scale, and definition of regime boundaries. Storm regimes are descriptive tools for dominant patterns rather than precise forecasts of individual events; ongoing research seeks to standardize methods and relate regimes to physical mechanisms and predictability.