Using clustering analysis for the sea level pressure field of the ERA-Interim reanalysis between 1979 and 2016, five synoptic pressure patterns have been obtained for the Drake area and Antarctic Peninsula (AP) region (45°–75°S, 20°–120°W), and the resulting daily series has been made available to the scientific community. The five patterns have been named according to their most important features as follows: low over the Weddell Sea (LWS), low over the Amundsen and Bellingshausen Seas (LAB), low over the Drake Passage (LDP), zonal flow over the Drake Passage (ZDP), and ridge over the Antarctic Peninsula (RAP). Each atmospheric pattern is described after analyzing its development and evolution. A frequency analysis shows that the five atmospheric patterns present a similar annual frequency but a large seasonal variability. The transitions from one pattern to another tend to follow a cycle in which synoptic atmospheric waves are displaced eastward by a quarter wavelength. Four of the five atmospheric patterns (all except RAP) are very influenced by the southern annular mode (SAM); however, only LAB and LWS are influenced to some degree by ENSO. The occurrence of the LAB pattern presents a positive trend showing agreement with other studies that indicate an enhancement of the Amundsen–Bellingshausen Seas low. Finally, atmospheric circulation patterns have been related to the airmass advection and precipitation in Livingston Island, showing the potential application for studying the changes in the surface mass balance on the AP cryosphere.

A study of electrically severe thunderstorms (>2000 cloud-to-ground flashes per day) in the Spanish territory of Castilla-Leon (northern plateau of the Iberian Peninsula) has been performed using 11 years (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010) of data. These episodes were classified according to average upper-level synoptic patterns. Seven synoptic patterns emerged: shortwave and very shortwave troughs, three types of lows, cyclonic vortex and ridge. The moisture content at low levels and static instability were also considered. In general, all the episodes were associated with instability and moderate moisture (11 g kg −1 for the average mixing ratio at 925 hPa). The electrically severe thunderstorms associated with five synoptic patterns (shortwave and very shortwave troughs, and three types of lows) generated hail, strong winds, and intense precipitation. By contrast, the cyclonic vortex and ridge synoptic types were not associated with severe weather.