North Sea: Weather types and gales since 1948
Air pressure is a fundamental weather and climate element and the very basis of every weather map. Daily air pressure distributions provide information on airflow and the influence of high and low pressure systems, define the character of weather activity and thus yield insight into synoptic weather conditions.
Based on the air pressure distribution over the North Sea, we have compiled a catalogue of daily weather types, which covers more than 70 years by way of annual calendars from 1948 to the present day.
Weather patterns fall into six weather types, namely four directional (NE=Northeast, SE SW, NW) and two rotational types: low pressure (C=cyclonic) and high pressure (A=anticyclonic).
The strength of the atmospheric circulation is tabulated together with the weather type, if thresholds for gale (>), severe gale (>>) or very severe gale (>>>) are reached or exceeded.
Scientific Technique and References
Weather typing and gale analysis employ an objective technique used by Jenkinson and Collison (1977) in automated identification of so-called Lamb weather types. The original plethora of 27 weather types was reduced to six main classes. The Peak-Over-Threshold technique used in gale force estimation was recalibrated (Loewe et al., 2013) to the NCEP/NCAR Reanalysis I “Daily Sea Level Pressure” dataset (Kalnay et al., 1996), the single source of raw data for all products presented under “Weather types and Gales”.
- Jenkinson und Collison, 1977, An initial Climatology of Gales over the North Sea, Synoptic Climatology Branch Memorandum, No. 62, 18pp., UK Met Office, Bracknell.
- Kalnay et al., 1996, The NCEP/NCAR 40-year Reanalysis Project, Bull. Amer. Meteor. Soc., 77, 437-471; DOI:
- Loewe et al., 2013, System Nordsee – 2006 & 2007: Zustand und Entwicklungen. Berichte des BSH, Nr. 49, Bundesamt für Seeschifffahrt und Hydrographie, Hamburg und Rostock.
- NCEP Reanalysis daily sea level pressure provided by the NOAA/OAR/ESRL PSL, Boulder, Colorado, USA.