Another Hawaiian wet season is nearly upon us and it’s time to start getting focused on heavy rains and flash flooding. While the past year has been very dry and many parts of Maui County are suffering from severe to extreme drought conditions, each department and agency must prepare for what we hope is a very wet season.

Last Wednesday, November 28th, we invited Kevin Kodama, Senior Service Hydrologist, National Weather Service, to provide us with an on-site briefing of their flash flood procedures and program updates.

Kevin’s message to us was that instead of a seasonal increase in rainfall, October and November brought record low precipitation totals at several locations across the state. Extreme drought is entrenched over the southwest slopes of lanai, western Molokai, the lower leeward slopes of the West Maui Mountains, the western slopes of Haleakala from Haiku to Kaupo, and southwest Maui from Kihei to Makena.  The Maui County Department of Water Supply has continued the ongoing call for a five percent reduction in water use for upcountry residents. The request for a ten percent reduction in water use by central and south Maui also remains in effect.

Although the Climate Prediction Center’s extended forecast indicates Hawaii will experience dryer than normal conditions through the rest of the year,the potential for heavy rain events increases in late winter into early spring, especially if La Nina/El Nino-neutral returns.This is the wet season, however, and it will run through March 2013. We have seen in the past that a storm can come at any time and cause flash flooding conditions that we must be prepared for.For an event to be considered a “flash flood”, it doesn’t need to be a wall of water coming down a gulch. A rapid rise of water (several feet over 15-30 minutes time) is more common.

Wet season preparedness reminders

• Clean gutters and drainage ditches
• If you live in a flood-prone area, identify your evacuation routes ahead of time
• Plan for more rainy weather impacts
• Increased road travel times or possible detours due to flooding
• Outdoor activities may be postponed, canceled, or adjusted
• The wet season always brings increased potential for lightning strikes
• Be prepared for power outages
• Move indoors during a thunderstorm
• Monitor media, NOAA Weather Radio, and Internet sources for changes in weather conditions
• Turn Around – Don’t Drown!

Find out more:
NOAA National Weather Service Honolulu
NOAA Weather Ready Nation
NOAA Climate Prediction Center
U.S. Drought Monitor
HI Dry Season Rainfall Maps