Flood watches remained in effect for Oahu, Molokai, Lanai, Maui, Kahoolawe and Hawaii Island through early Thursday, while Kauai dropped out of the watch as the heaviest rain shifted east, according to Hawaii News Now.

All schools on Molokai were closed on Wednesday because of flooded roads, the station reported. The National Weather Service's Honolulu office had a flood watch covering the same islands, with flash flooding possible through late Wednesday night and into early Thursday.

What changed overnight

The trough that brought the rain moved its axis eastward, pushing heavy rain and thunderstorms across Maui County and parts of Hawaii Island, including the Hamakua coast. Lighter showers were expected over the western end of the state, focused on windward and mauka areas.

The National Weather Service issued flood advisories for Oahu and Maui on Wednesday evening. The Oahu advisory covered windward areas including Kailua and Kaneohe, where radar and rain gauges showed rain falling at 0.5 to 1.5 inches per hour. The Maui advisory covered the eastern part of the island, including Hana, Kipahulu and Nahiku, with rates of 1 to 2.5 inches per hour. The Oahu advisory was issued at 9:19 p.m. HST and the Maui advisory at 8:24 p.m., and both were due to expire at 11:30 p.m.

The broader watch was issued at 3:29 p.m. and was set to expire at 5 a.m. Thursday. The weather service said the greatest threat was focused on Oahu and Maui County, with all islands at risk. The station's First Alert Weather Day continued into the night because of the potential for heavy rain.

Advisories are issued when flooding is happening or about to begin. A watch is broader: it means conditions are favourable for flash flooding, not that flooding is certain. The Honolulu watch listed impacts including closed roads, property damage in urban or low-lying areas, and landslides on steep terrain.

Where the rain has fallen

Hawaii News Now reported that rainfall totals have been beneficial overall. Molokai received the most rain and Kauai the least, with heavy pockets over the mountains. Hawaii Island saw a trace to about 3 inches, but not every area got rain.

The totals came in under the original model projections, with some neighbourhoods seeing drizzle rather than heavy rain. The station attributed that to a less significant upper-level jet and weaker dynamics than earlier model runs had suggested, along with a moist but not especially unstable air mass. The practical result was fewer extreme downpours than forecasters had feared.

That does not mean the threat is over. The air above the islands held about double its usual moisture, which keeps the capacity for heavier rain at times. The watch remained in place through early Thursday for that reason.

Island by island

Oahu was under a flood advisory for windward areas and remained in the watch. Maui County, which includes Molokai, Lanai, Maui and Kahoolawe, stayed under the watch, with an advisory for eastern Maui. Hawaii Island remained in the watch, with the Hamakua coast among the areas seeing heavier rain. Kauai was no longer under a watch, and the station reported that rain there had been limited.

Molokai's school closures were the most concrete disruption reported. The station did not say when schools would reopen or how many roads were affected.

What happens next

Conditions are expected to improve on Thursday or Friday, with trade winds returning for the weekend. A brief period of trade winds is expected Friday night into Saturday, and breezy northeast winds are forecast for Sunday as a shallow front moves near or over the state. Spotty heavy showers could linger.

Halloween trick-or-treating could be a little wet, mainly in windward and mauka neighbourhoods, according to the station's forecast.

For residents and travellers, the useful checks are local: whether their island is still under a watch or advisory, whether roads near streams and drainage channels are open, and whether the weather service has upgraded an advisory to a warning. The service's guidance is to stay away from streams, drainage ditches and low-lying areas prone to flooding.

What is not known

The rainfall totals are uneven and the station's figures are a snapshot, not a final tally. The report does not give a damage estimate, a list of closed roads or a reopening date for Molokai's schools. Forecast confidence is also limited: the same report notes that earlier model runs overestimated the thunderstorm threat, which is a reminder that rain totals can come in above or below expectations.

The watch and advisories have expiration times, and they can be extended, allowed to expire or replaced by warnings. Readers should check the current alert rather than rely on this summary.

Where the alerts stand

As of Wednesday evening in Hawaii, the flood watch covered Oahu, Molokai, Lanai, Maui, Kahoolawe and Hawaii Island through early Thursday. Kauai was out of the watch. Molokai closed its schools. Rain totals were below earlier projections, but the air remained unusually moist, and forecasters expected improvement late in the week, with trade winds back for the weekend.