After a prolonged stretch of impactful Kona weather and heavy rainfall across the state, a gradual return to a more typical northeast trade wind pattern is expected by midweek. A lingering moisture axis over the eastern end of the state, combined with an upper trough, will support periods of locally heavy showers on Tuesday, mainly over the Big Island. Thereafter, a drier and more stable trade wind pattern is expected from late week through the weekend and into early next week.
Latest satellite imagery shows the band of thunderstorms that impacted portions of the state earlier today has shifted well east of the Big Island, with mostly dry northeast trade wind conditions now prevailing across the island chain. Dewpoints have dropped into the lower 60s across the western end of the state, resulting in noticeably cooler and more comfortable conditions compared to recent days.
The past several days have been exceptionally wet across portions of the state, particularly from Oahu through the Big Island. Peak rainfall totals over the past 5 days have generally ranged from 15 to 25 inches in some areas, with a statewide peak of 25.73 inches observed at Kaala on Oahu—most of which fell Thursday night into Friday. This recent period of heavy rainfall has led to saturated soils and elevated streamflows, leaving areas very sensitive to additional rainfall.
Looking ahead through midweek, a lingering axis of moisture over the eastern end of the state combined with cold temperatures aloft associated with a departing but still influential upper trough will maintain the potential for locally heavy showers on Tuesday, especially across the Big Island. Given the saturated ground conditions, even modest additional rainfall could lead to renewed runoff and localized flooding concerns. As a result, a Flood Watch may need to be extended through Tuesday afternoon for the Big Island.
Elsewhere, more stable conditions are expected as trade winds strengthen and drier air filters into the region. By Wednesday and beyond, the state should transition into a more typical trade wind pattern featuring passing windward showers and generally drier leeward conditions. This pattern is expected to persist through the remainder of the week and into the weekend, consistent with broader guidance indicating decreasing moisture and a return to climatological conditions
High pressure building into the Hawaii region from the northwest will keep moderate to locally breezy trade winds in the forecast for the next few days. An upper level trough will keep periods of passing showers over the windward mountains of all islands with MVFR conditions possible in showers. IFR conditions are likely through the overnight hours at the Lanai airport due to saturated ground conditions.
Expect MVFR conditions with periods of showers forecast across the state favoring windward and mountain areas.
AIRMET Sierra for mountain obscuration remains in effect for Kauai Oahu, Molokai, Lanai, Maui, and windward Big Island.
Light icing remains possible in layer 130-FL200 IC over the Big Island.
Upper level energy diving down into a trough lingering near Big Island will keep the chance of eastern water showers and isolated storms alive through early Tuesday morning. High pressure building far north of the area will result in strengthened northeasterly winds across the islands. A Small Craft Advisory (SCA) has been issued for all waters due to these increasing northeasterlies. Winds will be strongest Tuesday but are expected to ease Wednesday and Thursday. Moderate to locally fresh trades will be in place through the remainder of the week.
A small, short period north swell will gradually decline tonight, while a small west-northwest persists. A reinforcing pulse of medium period north northeast swell will arrive Tuesday, peak in the afternoon into evening and then decline Wednesday. Another small, medium period west northwest swell will arrive Thursday, peak Friday, then decline during the weekend. Aside from areas along east shores exposed to the northerly swell, short period energy from rebuilding trades will increase to near seasonal averages Tuesday night and Wednesday and then hold into the weekend. A small south southwest swell will decline Tuesday and fade Wednesday. A short-lived pulse of small south southeast swell will be possible Wednesday through Friday, and a small south southwest swell could arrive Friday into the weekend.
Flood Watch until 6 AM HST Tuesday for Kona-Kohala-Big Island Interior-Big Island South-Big Island Southeast-Big Island East- Big Island North.
Winter Weather Advisory until 6 AM HST Tuesday for Big Island Summits.
Small Craft Advisory until 6 AM HST Wednesday for all Hawaiian waters-
