La Niña forecast again for wet season
Outlook tough for drought areas of Maui, Hawaii island
Similar to last year’s wet season, La Ni ñ a has again been forecast for October through April in Hawaii, which may not bode well for parched leeward areas of Maui County and Big Island.
“We could see drought ease in Maui County and the Big Island but still make it through the end of the wet season at the end of April of 2022, which would be really bad news as we head into the next dry season,” Kevin Kodama, senior service hydrologist for the National Weather Service in Honolulu, said during a Friday news conference on the Hawaiian Islands 2021-2022 Wet Season Rainfall Outlook. “Hopefully that won’t happen but when we look at how drought has behaved in similar situations.”
Coming off the dry season from May through September, each county suffered below average rainfall and dry conditions.
However, Maui County and the Big Island are continuing to experience severe drought conditions, which have sparked cattle and crop losses on Maui and a record-breaking brush fire on the Big Island.
The National Oceanic and Atmospheric Administration announced Thursday that another La Nina season with moderate intensity is likely in store for Hawaii, which means that heavy rainfall will typically focus on windward slopes, leaving leeward areas dry.
Also, Hawaii could see a slower start to the wet season, where the latter half gets the majority of the rain.
The wet season started late for Maui County last time around, Kodama said. Molokai was in exceptional drought conditions — the worst of the drought tiers — in early January. Rain events didn’t come until February and March but they were
few and far between, drying off quickly.
“That’s why Maui County got into drought conditions so fast, this dry season, because they did get some rain … it was just late in the wet season and really didn’t, it was just one or two events and so conditions are pretty bad,” he said during the conference.
Also, drought recovery is more likely on Oahu and Kauai, which have less intense drought. Both islands are smaller and rainfall can get into leeward areas more easily, Kodama said. Additionally, wet season weather systems have a greater chance of reaching Kauai and Oahu before they stall out and move eastward across the island chain.
Rainfall distribution is impacted by the strength of La Nina where stronger events have a higher than normal trade wind frequency and focused rainfall on windward areas. Weaker ones have more weather systems that yield significant leeward rainfall.
Wet season preparedness reminders, especially for windward areas that could experience high-intensity, fast events similar to flooding earlier this year, include the following:
¯ Do not drive on roads with fast-flowing water.
¯ Do not walk across flooded streams.
¯ If you live in a floodprone area, identify alternate routes ahead of time and also have an evacuation plan in case flood waters quickly threaten your home.