HONOLULU, Hawaii (HawaiiNewsNow) - A potent upper disturbance is forecast to pass over the islands Sunday, increasing the potential for a few thunderstorms and maybe a locally heavy downpour or two. The greatest threat for thunderstorm activity will be during the peak heating hours Sunday, especially for Molokai through the Big Island. Cold mid-level temperatures could also result in periodic snow showers for Mauna Kea and Mauna Loa on the Big Island, and even Haleakala on Maui, down to about 9,500 feet.
The disturbance should move out the neighborhood by Tuesday, with moderate northeast trade winds and mostly dry and stable conditions. A weak cold fron may move into the islands from the north around Thursday.
At the beach, a long-period south-southwest swell will arrive Sunday and peak just below advisory levels for south-facing shores on Monday. A small west-northwest swell will boost surf for west shores, while surf lowers on east shores as the trade winds decrease.