Nari, which hit the Philippines Saturday, was expected to move over Vietnam Tuesday and Wednesday, then weaken and light to moderate rainfall in Thailand, the Bangkok Post reported.
Supoj Tovichakchaikul, secretary-general of the Office of National Water and Flood Management Policy, said that, ideally, the storm would move to the north-northeast, filling the Bhumibol Dam in Tak, which is currently only at 47 percent capacity.
If Nari moves east, the Pasak Jolasid dam, which is currently at 112 percent capacity, risks flooding, Supoj said.
"[Nari] will fill more water but it must go to the north and northeast. Don't come to the east," Supoj said.
Three of Thailand's provinces -- Sa Kaeo, Prachin Buri and Chachoengsao -- are still flooded from storms on Sept. 17 and 28, the Disaster Prevention and Mitigation Department said.
About 3.5 million people have been affected by the floods.
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