While the southeastern U.S. is dealing with yet another round of severe weather, it looks like those in the Aloha State will also need to contend with severe weather far from the mainland too; severe thunderstorms, flooding rains, and even heavy snow are possible in Hawaii beginning late tonight into the weekend across the island chain.
According to the National Weather Service in Honolulu on the island of Oahu in the middle of the state, trade winds will diminish through tonight as a broad surface trough and upper disturbance move in. Added instability associated with these features will lead to an increasing threat for strong to severe thunderstorms and heavy rainfall late tonight through Saturday. Although the thunderstorm potential will lower Sunday into early next week, plenty of moisture lingering combined afternoon sea breezes and a broad surface trough nearby will support afternoon showers over interior and leeward areas each day. The wet pattern could continue through the latter half of next week as another upper disturbance approaches.
A potent storm system is expected to bring heavy rain, damaging winds, large hail, and even heavy snow to parts of Hawaii in the coming days. For now the view from Hilo on th3 Big Island shows the calm before the storm here:#HIwx pic.twitter.com/YrP74DReWm
— the Weatherboy (@theWeatherboy) May 10, 2024
National Weather Service meteorologist Genki Kino described the ingredients coming together to create a substantial storm across the state. A trough developing just west of Kauai will decrease the trade winds today with light to moderate east to southeast winds expected. A plume of moisture moved in from the east last night and is currently producing scattered showers mainly over windward and mountain areas. Sea breezes developing later this morning will lead to afternoon showers over interior and leeward areas. With some enhanced moisture already in place, we could see some downpours this afternoon. Also with the light winds, any showers will be slow moving and could cause some minor flooding impacts this afternoon through the evening hours.
Kino wrote, “An unusually strong upper level disturbance will begin to move into the area tonight and will bring the threat of flash flooding and isolated severe thunderstorms across the state. Initially the main threat will start over the smaller islands of Kauai, Oahu and Maui County and expand eastward to the Big Island during the day Friday.”
On Friday, the upper level trough is forecast to be centered near Kauai, the state’s westernmost main island, in the morning. It will then move east bringing an unstable environment across the entire state by the afternoon. Atmospheric ingredients will be ripe to produce isolated severe thunderstorms capable of producing large hail and gusty winds of greater than 50 mph. While Kauai will get the showers and storms first, it appears the best combination of moisture, instability, and shear will be from Oahu, across Maui, and to the Big Island of Hawaii.
“The main takeaway for Friday is that we are not looking at a widespread rain event,” Kino explains, adding, “Rather, we are looking at scattered heavy shower event with isolated strong to possibly severe thunderstorms. We do want to emphasize that flash flooding can occur well downstream from the mountains, where the weather could be fair. Also sudden changes of the weather will be possible. It could be sunny and fair weather one hour and you could be under a severe thunderstorm the next hour. ”
Due to the tall volcanic mountain peaks on the Big Island, the strongest winds are expected there along with the threat of heavy, accumulating snow. Several inches of snow are possible over the coming days.
