Blackouts persisted across five percent of Udon Thani province on Saturday night as electricity workers continued efforts to repair storm-damaged power lines.
The power disruption started in the northeastern province Friday evening as a storm hit nine of its 20 districts. On Saturday provincial authorities acknowledged reports of damage to 760 houses. The heaviest impact occurred in Udon Thani municipality.
Paibul Kraisee, chief of the provincial meteorological office, said wind speeds measured only 90 kilometres per hour Friday evening but there might have been a brief tornado that could not be measured but caused heavy damage to taller structures.
He referred to shattered glass panes at the Udon Thani provincial administration organisation building and Udon Thani Hospital.
Such storms during the seasonal transition could recur until the third week of this month when the rainy season is forecast to begin, Mr Paibul said.
Jadet Wisri, director of the Udon Thani office of the Provincial Electricity Authority, said blackouts were reported in nearly all areas of the province after a storm-tossed billboard brought down a main 115-kilovolt transmission line in front of Pairoj Hospital in Muang Udon Thani. That knocked out supplies to four power transmission substations. The storm also felled 70 high-power poles and 10 low-power poles.
About 200 electricity workers from Udon Thani, Loei, Nong Khai and Bangkok were deployed to repair the lines.
"Tonight blackouts will continue in five percent of the province and power will resume completely on Sunday," Mr Jadet said.
Wichien Khaokham, president of the Udon Thani provincial administration organisation, said its office was heavily damaged as the storm broke through its walls made from lightweight bricks on five floors.
Ratchayothin Meephanlom, the Udon Thani insurance supervisor, said motorists reported damage to more than 40 vehicles hit by billboards, fallen roofs and branches. There was no third-party insurance for billboards which have been proliferating in the province, he said.