HONOLULU (KHON2) — A surface low across the western islands continues to trigger deep convection far southwest from Oahu and Molokai, but this activity has decreased a bit across local waters within the past few hours. Nevertheless, the threat for flash flooding remains sufficiently high to keep a Flash Flood Watch up for Kauai and Niihau through tonight. The surface trough is expected to move west of Kauai by Wednesday morning and the threat for flash flooding will decrease.
An upper trough straddling the state provided instability that fueled heavy rainfall over Kauai and isolated downpours over the rest of the state earlier today. An increase in clouds is expected tonight over the eastern islands as mid and upper clouds stream overhead from the south. Once the surface trough pushes west of Kauai, easterly trade winds will spread across the state with showers focused over windward and mountain areas. However, models show the upper trough remaining through the week. Therefore, we expect a wet trade wind pattern with rainfall maximum overnight and during the early morning hours.