The National Weather Service can't say for sure, but meteorologists suspect the thunder and lightning storm that rushed over the Islands late Thursday night and yesterday morning brought with it hail and a tornado, as well as lightning.

And for a second straight night, O'ahu was hit hard yesterday by heavy rain.

The downpour caused a mudslide in the 2700-block of Round Top Drive, where two slides were reported earlier this week. Last night's slide occurred shortly before 8 and was "four times bigger than the previous" slides, said city spokesman Mark Matsunaga.

Police were forced to close that stretch of Round Top Drive until the debris could be removed.

In Manoa Valley, a mudslide was reported on Paty Drive and rocks and debris slid onto Beaumont Woods Place.

A swollen Makiki Stream caused flooding in the McCully area and closed several roadways, while Kalakaua Avenue and other streets in Waikiki were closed temporarily because of flooding.

Firefighters were kept busy responding to calls of manhole covers being displaced by storm water and residents reporting flooding at their homes. There were no reports of major damage.

Tornadoes and hail are rare in Hawai'i, said Wes Browning, meteorologist for the National Weather Service, but both likely occurred early yesterday morning. The tornado is suspected of causing damage at Kaumalapau Harbor on Lana'i, blowing a trailer off its foundation and sending it 10 feet down a berm onto a roadway.

The hail, about an inch in diameter, hit the Kona Coast of the Big Island.

"Thunderstorms set off the tornado," Browning said, adding that the last one recorded in Hawai'i was in December in 'Aiea. "Basically, the entire thunderstorm starts to rotate."

Yesterday's unusually rough weather late in the evening was accompanied by the heavy rains that have saturated the Islands over the past few weeks. Crews on O'ahu spent yesterday mopping up roads and clearing waterways, while parks and golf courses were forced to close because of the heavy showers. The municipal golf courses are expected to reopen today, provided they are dry enough for play. Players with tee times are urged to call first before going to the courses.

Other damage caused by the rain yesterday were the third landslide on Round Top Drive in as many days and a 42-inch sewer main rupture sometime before 7 a.m. at Kai'olu Street. The rupture forced the closure of the left lane of Ala Wai Boulevard as repairs were made. Some of the untreated sewage from the break spilled into a storm drain that leads to the Ala Wai Canal, city Environmental Services officials said.

Warning signs were posted along the canal and various points downstream. Officials said the public is advised to heed the signs and avoid contact with the affected waters.

While sewage spills and landslides have almost become commonplace over the past week, the tornado and hail were a new twist in the wet winter weather.

No one witnessed the tornado on Lana'i, Browning said, and the only way to determine if one had struck is to study the path and see if there's evidence of rotation. However, the weather service did detect the possibility of a tornado earlier and had issued a tornado warning on the island about half an hour before the suspected tornado struck.

The suspected tornado at Kaumalapau Harbor yesterday scattered empty cargo containers and snapped the top of a utility pole, Browning said.

As for the hail, it was reported by Big Island residents in Kealakekua after a severe thunderstorm slammed into the Kona Coast at about 9:35 a.m.

The last time hail as big as yesterday's fell was 2003, also on the Big Island, he said. No damage was reported from the hail.

On O'ahu, most of the concern was over the landslides. Larry Leopardi, chief of the city's road maintenance division, said his crew was out until 3 a.m. yesterday on Round Top Drive clearing a slide from state land.

The state Department of Land and Natural Resources has hired an engineering firm to assess the site and make recommendations for it and for another landslide moving from state land onto two Manoa homes, according to a storm update from the DLNR.

Leopardi said his crews were checking low areas and responding to complaints yesterday, and that they will be working today and Monday, a state holiday.

Reach Eloise Aguiar at eaguiar@honoluluadvertiser.com and Curtis Lum at culum@honoluluadvertiser.com.