The intent of the following graphs and descriptions is to address the changes of precipitation during an El Nino and a La Nina event as compared to the historical average of precipitation. The PEAC Center in association with The University of Hawaii and JIMAR (Joint Institute for Marine and Atmospheric Research) have compiled the following information in hopes that it will serve as an aid to agricultural interests in the Kona District.
The Kona district of the Big Island of Hawaii is located in the leeward area of Mauna Kea, or on the southwest coast. The Atlas of Hawaii Third Edition by the Department of Geography, University of Hawaii at Hilo provides information on the rainfall patterns for the Kona area. It states: "On the Kona Coast of Hawaii Island, a unique summer maximum rainfall pattern occurs. There the prevailing winds are effectively blocked by two large mountains, Mauna Loa and Hualalai. In the absence of strong trades, ocean-land temperature and pressure differences generate local diurnal variations in the wind. Surface heating causes upslope winds during the day that give rise to convective rainfall at middle elevations (the "coffee belt") in the afternoon. Wind direction reverses at night, as cooled mountain air moves downslope. Increased surface heating in summer intensifies this process, resulting in the only summer rainfall maximum in the state." Therefore, rainfall in the Kona area is very important to agricultural interests. For certain crops, such as coffee beans, the growing process is highly dependent on rainfall and temperature, especially at certain times of the year. These graphs and descriptions were prepared to help meet the requirement for specific and accurate climate information regarding climate variability to aid in agricultural decision making and to evaluate possible impacts caused by low rainfall amounts.