Monthly Climate and Impacts Report for Hawaii - August 2012
Chris O'Connor and Dr. Pao-Shin Chu
Hawaii State Climate Office
Department of Meteorology
University of Hawaii
Honolulu, HI 96822
Precipitation and Temperature
August 2012 was drier than normal as we saw a dry trend continue, which has been present throughout the entire summer. The beginning part of the month saw minimal rainfall, though we did experience a slight increase in rainfall activity towards the end of the month, especially in the Hilo area. All four airports reported rainfall significantly below their normal totals. Drought conditions across the state remained approximately the same from last month, with Oahu and Kauai ranging from "Abnormally Dry" (D0) to "Moderate Drought" (D1), while the eastern islands have areas ranging from "Abnormally Dry" (D0) to "Extreme Drought" (D3) on a scale of D0-D4. Interestingly, Niihau is completely drought free, as well as northwestern shores of Maui and Hawai'i.
Across the state, mean temperatures as well as mean highs and mean lows were below their respective historical averages. Generally this is a sign of increased cloudiness blocking both incoming solar radiation and outgoing longwave radiation, effectively reducing the diurnal temperature range. This is confirmed by observations, all four airports had more than 18 days as "partly cloudy" or cloudier.
The NOAA Climate Prediction Center seasonal outlook for Hawaii predicted below normal precipitation and below normal temperatures for the entire state in September 2012.
The La Nina conditions, which have been dominant the past two years, are entirely reverted back to ENSO-neutral conditions, and we are in fact seeing a possible weak El Nino formation for next winter. The atmospheric circulation over the tropical Pacific is near average, while equatorial seas surface temperatures are greater than 0.5 °C above average across the eastern Pacific Ocean. NOAA is calling for El Nino conditions likely to develop during the next six months.
The Hawaiian weather was fairly calm throughout the month, but the effects of drought were felt state-wide. On Kauai pastures have been degrading to the point where ranchers have been forced to reduce their herd sizes. Oahu pastures are also in poor condition, while there have been reports of some ranchers de-stocking their pastures in Waialua. Deer have been reportedly damaging crops on Molokai as they search for food and water. The island itself has been very dry and suffering from low water levels in reservoirs, especially the Kualapuu Reservoir. As a result, a 30% reduction in irrigation water consumption has been ordered. The same story of poor general vegetation due to low water levels persists on Lanai and Maui islands. On Hawai'i, conditions have been so extremely dry, that a rancher near Waimea has been hauling 5000 gallons of water each week for his cattle.