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National Weather Service Report
June 3, 2010

A few leeward areas on Kauai and Oahu received near to above normal rainfall in May but the rest of the state experienced drier than normal conditions. Thus…exceptional drought…or D4 category on the U.S. drought monitor map…continued for a third consecutive month in the South Kohala district of the Big Island. Extreme drought conditions…or D3 category…also remained in place over most areas in the Ka‘u…North Kona and South Kona districts.

Maui County also has persistent areas of extreme drought over the lower elevations of leeward Maui and the western two-thirds of Molokai. The island of Lanai also has ongoing severe drought conditions…or D2 category…affecting agricultural interests.

On Oahu…below normal rainfall over the east end of the island along with warmer temperatures resulted in a substantial drop in levels within the Waimanalo reservoir which supplies irrigation water. The declining water levels prompted the State of Hawaii Department of Agriculture to impose a 30 percent cutback in irrigation water use and service on limited hours only three days per week. As a result…this area of the island is now considered to be under extreme drought in the U.S. Drought Monitor Map.

The last time the State of Hawaii was considered to be drought-free was April 15 2008. Since then…various areas of the main Hawaiian Islands have been under at least moderate drought conditions. The ongoing episode of extreme drought began nearly a year ago on July 7 2009.

summary of impacts…

Kauai
Pastures in the windward areas of the island continued to improve over the past month. However…pastures in the Mahaulepu and Koloa areas have not benefited from the trade wind rainfall and remain in a degraded state.

Oahu
As indicated above…a mandatory 30 percent cutback in irrigation water use and a reduction in service hours is currently in place for the Waimanalo reservoir.

Molokai
No changes since May 5. Pasture and general vegetation conditions remain poor over the western two-thirds of the island. Water levels within the Kualapuu reservoir in West Molokai remain low and state agriculture officials continue to enforce a mandatory 20 percent reduction in irrigation water use.

Lanai
No changes since May 5. Pastures and general vegetation conditions remain in a degraded state.

Maui
No changes since May 5. Pastures and general vegetation conditions remain poor. Upcountry reservoir levels have been decreasing in recent weeks reflecting a decline in flow from windward streams. The Maui County Department of Water Supply continues to request a 5 percent reduction in water use by upcountry residents…and a 10 percent reduction in water use by central Maui residents.

Big Island
Conditions remain very poor in general along the leeward areas of the island. The ongoing drought has significantly affected a wide range of agricultural products including coffee…avocados… rambutan… bananas…macadamia nuts…loquat and jaboticaba. Only drought-resistant trees and crops have been producing well. Ranchers in the lower Ka‘u and leeward Kohala slopes continue to operate under very poor conditions for livestock. Significant amounts of supplemental feed have been required as pastures have been insufficient to support the herds. Old and sick cattle have been dying.

Many areas of the western and southern sections of the Big Island are also vulnerable to brush fires. Residents dependent on rainwater catchment have been using costly water hauling services to satisfy basic needs.

Following a spring recovery…recent dryness has resulted in a renewed deterioration of pasture and vegetation conditions along the windward slopes of the island. Continued drier than normal conditions may soon begin to impact residents on water catchment sources.

Climate Summary

According to the NOAA Climate Prediction Center…El Nino has transitioned to a neutral state. There are increasing indications That La Nina may develop during the latter half of 2010. La Nina is an anomalous cooling of sea surface temperatures in the equatorial region of the Pacific.

Precipitation/Temperature Outlook

The long-lead Hawaiian Islands outlook issued on may 20 by the NOAA Climate Prediction Center indicates probabilities favoring below normal precipitation through summer 2010. In previous summers… below normal rainfall along the windward slopes manifested itself as a decrease in rainfall per day while the number of rain-days per month remained near normal. The next long-lead outlook will be issued on June 17.

June is normally one of the driest months of the year in the Hawaiian Islands. thus…drought conditions are expected to expand or worsen over the next several weeks…especially in the leeward areas. The main exception is the middle and upper Kona slopes. This is the only leeward area in the state which has a summer maximum in rainfall.

Hydrologic Summary and Outlook

U.S. Geological Survey 28-day averages indicate all monitored streams in the Hawaiian Islands to be at near to below normal flow levels. As the dry season continues…more sites are expected to drop into the below normal range…especially in the leeward areas of the state.

For more info:

U.S. Drought Monitor
http://www.drought.unl.edu/dm/monitor.html

Hawaii Drought Monitor
http://www.hawaiidrought.com

USGS Hawaii – recent conditions
http://hi.water.usgs.gov/recent/index.html

Climate Prediction Center Long-Lead Hawaii Outlook
http://www.cpc.ncep.noaa.gov/products/predictions/90day/fxhw40.html