UPDATE: 12:15 p.m.

The National Weather Service has issued a flood advisory for Molokai until 2:30 p.m. today.

“At 11:20 a.m., radar indicated heavy rain over eastern Molokai. Rain was falling at a rate of 1 to 2 inches per hour,” the advisory said.

Locations covered by the advisory include Pukoo, Ualapue, Halawa Valley and Kamalo.

Rainfall and runoff may cause hazardous driving conditions on Kamehameha V Highway (State Route 450), forecasters said.

10:55 a.m.

The National Weather Service has issued a flood advisory for Oahu until 1:30 p.m. today.

“At 10:27 a.m., radar and automated rain gauges indicated heavy rain over central Oahu. Rain was falling at a rate of 1 to 2 inches per hour,” the advisory said.

Locations covered by the advisory include Honolulu, Waipio, Mililani, Pearl City, Waikele, Wahiawa, Wheeler Field, Aiea, Waipahu, Kunia, Halawa, Waiahole, Waikane, Schofield Barracks, Salt Lake, Moanalua, Kahaluu, Ahuimanu, Iroquois Point and Ewa Beach.

The heavy rain may cause minor flooding on roads, poor drainage areas and in streams, forecasters said.

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An unseasonably cold weather system is moving across the state today, triggering flood watches for most islands and bringing the threat of thunderstorms and locally heavy rain.

The National Weather Service issued a flood watch through this afternoon for Niihau, Kauai, Oahu, Molokai, Lanai, Kahoolawe and Maui. Forecasters said an unstable upper-level low will settle over Kauai around noon before weakening and drifting slowly east tonight.

“Unstable conditions within this upper low will likely produce periods of thunderstorms and heavy showers, potentially leading to flash flooding conditions in some areas,” the weather service said.

Additionally, a coastal flood statement has been issued from late tonight through Monday afternoon for all islands. Peak monthly high tides combined with water levels running higher than predicted will lead to minor flooding along the shoreline and in low-lying coastal areas during the late afternoon hours.

Impacts could include saltwater inundation of vulnerable roadways, beaches and docks. Drivers should avoid flooded roads and rinse vehicles with fresh water if they are forced to drive through salt water, weather officials said.

Mariners are under a small craft advisory until 6 a.m. Saturday for windward and leeward waters of Maui County and Hawaii island’s windward waters. Northeast to east winds up to 25 knots are expected to make conditions hazardous for smaller vessels.

Meanwhile, residents on Hawaii island are being cautioned about periods of light ashfall from Kilauea volcano. While Episode 47 of the summit eruption paused overnight, tradewinds continue to push lingering ash toward the southwest, particularly over the Kau District.

The forecast for today includes showers and isolated thunderstorms this afternoon across most islands. Locally heavy rain is possible with highs between 80 and 85 degrees and east winds blowing at 15 to 20 mph.

On Saturday, conditions will remain mostly cloudy with scattered showers favoring windward and mauka areas. Highs will range from 82 to 87 degrees with lows from 74 to 79.

Sunday will be partly cloudy with scattered showers for windward slopes and highs between 83 and 88 degrees. The upper low is expected to move further away, decreasing the threat of thunderstorms.

The work week starts Monday with partly cloudy conditions and scattered windward showers. Tuesday will turn breezy with tradewinds increasing to 15 to 25 mph and scattered showers focused over windward and mauka areas. Highs will stay consistent in the low to mid-80s throughout the period.