A Review of Concepts in Hawaiian Climatology 1 
Luna B. Leopold and C K. Stidd 2 
In Hawaii, which is noted for its equable 
climate, the lack of great variations between 
seasons often obscures the importance of day- 
to-day and geographic variations in weather. 
Hawaii owes its relatively uniform climate to 
its position with respect to the sub-tropical 
high pressure cell and accompanying ocean cur- 
rents. The rugged topography causes salient 
orographic rainfall patterns. The variations in 
annual rainfall through short horizontal dis- 
tances are common knowledge among residents 
of Hawaii. Areas in the mountains immediately 
behind Honolulu receive up to 160 inches an- 
nually, while at the seashore, 5.5 miles away 
from the mountains, less than 15 inches is re- 
corded. On Kauai, the annual mean varies 
from 450 to 20 inches in a horizontal distance 
of 12 miles. 
The changes of greatest economic importance, 
surprisingly enough, are those that occur be- 
tween consecutive months and between con- 
secutive years. The growing of pineapples and 
of sugar cane represents the two most important 
industries in the Hawaiian Islands. These in- 
dustries, which utilize a large proportion of the 
arable land in the rainfall zone between 20 and 
100 inches, have found that the wide variations 
in rainfall from the mean in consecutive months 
and consecutive years constitute one of the most 
critical risks in their operations. 
1 Published with the approval of the Director as 
Technical Paper No. 181 of the Pineapple Research 
Institute, University of Hawaii. Manuscript received 
November 5, 1948. 
* Head, Department of Meteorology, Pineapple Re- 
search Institute, and Experiment Station, Hawaiian 
Sugar Planters’ Association; Research Meteorologist, 
U. S. Weather Bureau, Honolulu; respectively. 
A program of research aimed at improvement 
of short- and long-range forecasts has been initi- 
ated by the sugar and pineapple industries of 
Hawaii in cooperation with the U. S. Weather 
Bureau. In the course of the work it has become 
clear that the investigations of Hawaiian climate 
in the past have been of such diverse character 
that a summary of present knowledge would be 
of assistance to those workers concerned with 
climatologic problems of these latitudes. 
STORM TYPES 
A clear-cut definition of storm types is prob- 
ably somewhat more difficult than it was thought 
to be in the past. Besides orographic rain result- 
ing from lifting of the trade winds, Jones 
(1939) stressed the importance of what he 
called ''cyclonic activity.” He asserted that what 
is locally known as "kona weather” in Hawaii 
is associated with "cyclonic” or frontal activity. 
The word kona, interpreted as leeward, bears 
the connotation of winds from south or west 
(leeward with respect to the normal trade 
winds). Kona weather has also been described 
by Daingerfield (1921) and by Leopold 
(1948). 
Jones pictured the periods of heavy rainfall 
as frontal passages of the temperate latitude 
type. Later work has shown that many dis- 
turbances, particularly in summer, are of the 
subtropical character as defined by Riehl 
(1945). During periods when the semi- 
permanent anticyclone of the eastern Pacific is 
strong, Hawaii derives rainfall from easterly 
waves — low pressure troughs moving toward 
the west in the trade wind current. Riehl ( MS. ) 
states that "weather conditions in winter are 
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