The Philippines’ weather bureau issued alerts for flash floods, landslides and strong to gale- force winds as tropical storm Songda strengthened and threatens to enhance a southwest monsoon.

Songda was 338 miles east of Eastern Samar province at 10 a.m. local time Monday, the Philippine Atmospheric, Geophysical & Astronomical Services Administration said. The storm’s maximum sustained winds accelerated to 105 kilometers per hour with gusts at 135 kilometers per hour, the weather bureau said.

“The Philippines will be extremely wet in the next three days,” Science and Technology Undersecretary Graciano Yumul said in a press briefing in Manila. The storm is “huge and it’s carrying a lot of rain.”

Storm warning signal number 1, the lowest in the agency’s four-scale alert system, has been hoisted in the provinces of Camarines Sur, Catanduanes, Albay and Sorsogon. Typhoon Aere hit the Southeast Asian nation earlier this month, killing 35 people and damaging ($32 million worth of agriculture and infrastructure in the same areas Songda now threatens.

Rice Output

Rice production in the regions of Bicol and Eastern Visayas, where the three provinces are located, is forecast at 574,631 tons this quarter, or 16 percent of the 3.57 million ton national total, according to Bureau of Agricultural Statistics data.

Songda will make landfall in the northern provinces of Cagayan and Isabela as early as late Thursday, and will enhance a southwest monsoon that will bring rains in Manila during the weekend, Yumul said.

“Fishing boats and other small sea craft are advised not to venture out onto the sea while larger sea vessels are alerted against big waves,” the weather agency said. Residents in low- lying and mountainous areas were warned against flash floods and landslides, the National Disaster Risk Reduction & Management Council said.

President Benigno Aquino, who is scheduled to visit Thailand later this week, ordered relief supplies to be delivered in advance and preemptive evacuation “if necessary” in areas to be hit by the storm, his spokesman Edwin Lacierda said by phone Monday.

The Philippines is battered by about 20 tropical cyclones yearly. In September 2009, Tropical Storm Ketsana submerged most of Manila after dropping 41 centimeters of rain in six hours, killing more than 400 people. Floods and landslides caused by back-to-back storms that year killed almost a thousand people and destroyed crops and properties, with damages estimated at $4.4 billion.

The Southeast Asian nation is expecting “stronger” storms this year due to the La Nina weather phenomenon. As many as 21 storms may hit the country in 2011 compared with 11 in 2010, Yumul said.