Factors Influencing the Forecast of a Polar Low Linked to a Tropopause Polar Vortex

Polar lows are strong mesoscale cyclones occurring over open waters in polar regions that can be associated with strong surface winds and heavy precipitation that may adversely impact polar communities and maritime activities. Tropopause polar vortices (TPVs) are coherent, tropopause-based cyclonic vortices that can influence the evolution of polar lows. Independent databases of polar lows and TPVs over the Nordic Seas are jointly analyzed to identify polar lows linked to TPVs. Approximately 74% of polar lows are found to be linked to TPVs. A polar low linked to a TPV that occurred during 10–11 February 2011 near the northern Scandinavian Coast was selected and analyzed using cloud-resolving forecasts from the Coupled Ocean–Atmosphere Mesoscale Prediction System (COAMPS). The sensitivity of the evolution of the polar low to forecast initialization time, microphysics, moist processes, and surface heat fluxes are examined. The polar low intensifies in a region of relatively strong lower-to-midtropospheric baroclinicity found between a region of relatively warm air associated with an upper-tropospheric ridge over the Greenland and Norwegian Seas and a lower-to-midtropospheric cold pool associated with a TPV over the Barents Sea. The lower-to-midtropospheric cold pool associated with the TPV contributes to weak static stability in the vicinity of the polar low. The weak static stability and enhanced surface heat fluxes in the vicinity of the polar low likely support convection and associated latent heating that contribute to the intensification of the polar low. The intensity of the polar low exhibits notable sensitivity to forecast initialization time and some sensitivity to microphysics. Withholding moist processes and surface heat fluxes individually result in a much weaker polar low.