Diagnostic Studies of Two Contrasting Rainfall Episodes in Hawaii: Dry 1981 and Wet 1982

Abstract

The circulation features that accompanied the dry January/February of 1981 and the wet January/February of 1982 in Hawaii are compared. The results indicate that surface and upper-air circulation features are very distinct during these two winter months with contrasting rainfall extremes. Four major synoptic patterns (frontal, kona, trade, and ridge) that influence Hawaiian rainfall have been described. The Kona storm pattern contributes to most of the rainfall in wet 1982, followed by the frontal pattern. No kona storm days occurred during dry 1981, and the rainfalls on frontal days in dry 1981 were less than half of those in wet 1982. The trade wind and ridge patterns are not Important for rainfall either in dry 1981 or wet 1982. A possible relationship between the PNA pattern and rainfall anomalies during these two non-ENSO winter months is suggested.