Polar lows are intense mesoscale weather systems which develop in response to combinations of upper tropospheric vorticity advection, low‐level baroclinicity near the sea ice‐ocean margin and strong air‐sea thermodynamical fluxes. In this paper, an evaluation of the associations between dominant patterns of low‐frequency variability in the atmospheric circulation and polar low developments over the North Atlantic during winter is presented. Because polar lows are rather poorly represented in reanalyses, the temperature (T500) and geopotential height at 500 hPa, the wind at 925 hPa, the SST, and the difference (SST‐T500), which are critical for their formation, are considered. The North Atlantic Oscillation (NAO) has a strong impact on all these variables, but it is contrasted spatially and temporally. Polar low formation is stimulated in the Labrador Sea for a positive NAO phase, while over the Norwegian Sea, there is an increase of polar lows forming on the flank of synoptic storms. Still over the Norwegian Sea, higher SST from January on favor the formation of polar lows of predominantly convective nature, while to the east of Greenland, the reduction of sea ice plus the northerly low‐level flow lead to a larger number of polar lows. Other teleconnection patterns also exhibit associations with polar low developments. The Scandinavia pattern shows a strong negative association with the studied variables over the Norwegian and Barents seas, but only marginally affects the Labrador Sea. The formation of polar lows is encouraged over the Norwegian and Greenland seas when the Polar/Eurasia pattern is in its negative phase.

International audienceCold-air mesocyclones remain a forecasting challenge in the southern hemisphere middle and higher latitudes, where conventional observations are lacking. One way to improve mesocyclone predictability is to determine their larger-scale circulation environments and associations with teleconnection patterns. To help realize this objective, reanalysis datasets on atmospheric and upper-ocean synoptic variables important in mesocyclone development are composited and compared to previously published mesocyclone spatial inventories. These analyses demonstrate a consistent association between higher frequencies of mesocyclones, greater sea ice extent and large positive differences in the SST minus low-altitude air temperature fields, coinciding with enhanced westerly low-level winds having a southerly component. Composites in the 1979 2001 period also were formed for opposite phases of El Niño Southern Oscillation (ENSO), the Southern Annular Mode (SAM) and the Trans-Polar Index (TPI). Regions likely to be favorable for mesocyclone development relative to climatology were identified. The largest (smallest) variations in meso-cyclogenesis occur in the South Pacific (South Indian Ocean, south of Australia), and are dominated by ENSO. The SAM and TPI are of secondary importance, yet still influential, and exhibit strong regional-scale variations