Skies over Oahu are expected to clear this morning as a storm system that prompted a flash-flood watch Tuesday moves to the east, the National Weather Service said.
"Look for calmer conditions, more return to a regular tradewind regime with more sunshine and light to moderate trades," said Henry Lau, a forecaster at the National Weather Service. "I believe the worst of it is gone."
A flood watch was in effect through 6 a.m. today for Oahu, Molokai, Maui and Hawaii island. The weather service said there was potential for heavy flooding overnight from Oahu to Hawaii.
There were two periods of heavy rainfall overnight Monday, one after 10 p.m. and another substantial soaking after 2 a.m. The weather service issued a flood warning at about 2:26 a.m. because a thunderstorm covered several miles of Oahu, from Hawaii Kai to Mililani.
"It was really coming down in buckets," Lau said. "I wouldn’t be surprised like 2 to 3 inches an hour."
A rush of water near the H-1 through downtown picked up soil as it moved down an embankment and dumped its load on the freeway’s Ewa-bound lanes near the School Street offramp. That caused lane closings that backed up traffic for hours during the morning commute.
State Department of Transportation spokesman Dan Meisenzahl said the incident was not a mudslide or a collapse of a retaining wall. He said debris, mainly topsoil, washed onto the road from surrounding areas. If it had been a mudslide, rocks, boulders and other materials would have been on the road, he said.
The H-1 was closed from 3:30 to 7:20 a.m., backing up traffic on the freeway and Pali Highway.
Meisenzahl said other H-1 Ewa-bound lanes were closed after a pump failed to drain the low-lying area under the Punahou Street overpass. Police closed the lanes from about 3:30 to 5 a.m. Two lanes of the freeway between Alexander and Punahou streets were reopened after floodwater drained.
Heavy rainfall also caused Manoa Stream to top its banks at about 2:45 a.m. Tuesday near the Woodlawn Drive bridge, inundating nearby property with nearly a foot of water and mud, the weather service reported.
The weather is also believed responsible for stalled vehicles and minor accidents from Mililani to Kalihi.
The city opened its emergency management center at 2:45 a.m. to monitor the situation, said John Cummings, spokesman for the city Emergency Services Department.
Seven inches of rain fell in Moanalua in the 24-hour period ending at 5 a.m. Upper Nuuanu recorded 6 inches, and 5.4 inches fell in Manoa in that period.
