Synoptic structure and evolution of a kona low

A subtropical cyclone or kona low affected the island of Hawaii on 24-28 Fe bruary 1997 and brought with it record winds at Hilo, large hail, blizzard conditions at higher elevations, and high surf. Damage estimates for the st orm due to crop loss, property damage, and utility line destruction exceed $4 million. A derailed case study of the storm was conducted using all avai lable operational data and data from the National Centers for Environmental Prediction-National Center for Atmospheric Research reanalysis dataset. Th e kona low formed on 23 February 1997 along a stalled trough northeast of t he Hawaiian Islands and is investigated during five evolutionary stages: (i ) incipient. (ii) intensifying, (iii) mature, (iv) weakening, and (v) dissi pating. The system's initial development is linked to dynamics at the 250-mb level. The maximum circulation, absolute vorticity, divergence. and height anomal ies all occurred at 250 mb during the period of most rapid deepening. Cold anomalies occurred in a deep layer between 850 and 250 mb that tilted eastw ard with height. Quasigeostrophic analysis showed enhanced vorticity to the west of a thickness trough, a configuration that maintained an area of pos itive vorticity advection to the west of the surface low and over new conve ction east and southeast of the low. The vorticity tendency is dominated by the advection of vorticity aloft in this case. especially during the incip ient and intensifying stages. The vorticity tendency is dominated by the ge neration of vorticity by divergence in the lower troposphere. Cloud bands with embedded convective cells formed on the low's eastern side and propagated eastward. eventually leaving the area of synoptic-scale asc ent and losing their convective properties. Areas where the best-lifted ind ex values were less than zero and areas of positive low-level advection of equivalent potential temperature coincided with regions of deep convection, as inferred from satellite imagery.