Meteorological analysis of the October 29, 2000 Hana storm

xii, 93 leavesOn the 29th of October, 2000, the Hana region on Maui received - 700 mm of rain in 7 hours. Radar analyses revealed that the storm responsible for the rain consisted of 7 cells that formed along the southeast slopes of Haleakala. The storm changed character from a series of ordinary cells that repeatedly moved over the Hana region to a quasi-steady cell that survived for nearly 4 hours. This cell accounted for - 80% of the rain recorded during the event and had a top that reached above the tropopause, a weak echo region, hail 25 mm in diameter, and maximum reflectivities above 60 dBZ. In contrast to the earlier ordinary cells, the quasi-steady cell moved to the right of the mean cloud-bearing winds. An upper-level low with its center located 500 km north of Hawaii provided large scale lifting that eliminated the trade wind inversion, a persistent feature over the state. The interaction of the confluence line triggered by the island of Hawaii and the high terrain of Maui appeared to be responsible for the formation of the storm over the Hana region. The low-level upslope flow provided continued forcing for the series of cells, and the terrain may also be responsible for keeping any downdrafts and outflows from disturbing the continuing cell formation. The advection of colder air in the core of a passing short-wave trough enhanced the instability in the area which initiated the development of the intense quasi-steady cell. The author hypothesizes that the quasisteady cell developed downdrafts with a flow that differed from the prior cells, resulting in an interaction with the low-level flow that maintained the cell for an extended period