Philippine Sea: Tropical Storm Omais tracking north-northwestward in the Philippine Sea as of Aug. 22 /update 10

Event

Tropical Storm Omais is tracking north-northwestward in the Philippine Sea, away from Miyako Island, Okinawa Prefecture, Japan Aug. 22. As of 18:00 JST, the storm's center of circulation was approximately 294 km (183 miles) west-southwest of Kadena Air Base, Okinawa Prefecture, Japan. Forecast models indicate that Omais will weaken into a tropical depression as it continues north-northwest through early Aug. 23. The system is forecast to weaken slightly and turn north-northeastward over the East China Sea toward South Korea, making landfall as a tropical depression over southern South Gyeongsang Province late Aug. 23. After landfall, the storm will weaken as it tracks northeastward across South Gyeongsang Province, then Daegu Metropolitan City, and likely dissipate over southern North Gyeongsang Province early Aug. 24. Some uncertainty remains in the track and intensity forecast, and changes may occur in the coming days.

Government Advisories
As of Aug. 22, the Japan Meteorological Agency has issued orange (the second-highest level on a three-tier scale) storm and large wave warnings for the Miyako Island Region, Okinawa Prefecture, through at least Aug. 22. Officials could issue new warnings and/or watches in response to the developing system in the coming days.

Hazardous Conditions
The storm may bring heavy rainfall and rough seas to coastal areas of far southern Japan and far eastern China over the coming days. Sustained heavy rainfall could trigger flooding in low-lying communities near streams, creeks, rivers, and urban areas with easily overwhelmed or a lack of stormwater drainage systems. Sites located downstream of large reservoirs could experience flash flooding after relatively short periods of intense rainfall. Rain-induced landslides are possible in steeply sloped terrains. Flooding could isolate some communities for several days. Torrential precipitation could trigger flash floods and mudslides. Forecasts indicate that 15 cm (6 inches) of rainfall can be expected for the Okinawa Region through Aug. 23.

Prolonged swells and storm surge generated by the system will likely result in coastal flooding. Persistent onshore flow could make it difficult for the surge to recede and for water levels to decrease in coastal river catchments. The Okinawa Region is forecast to be impacted by wave heights of up to 6 m (19.5 feet) through Aug. 22.

Transport
In addition to the immediate threat to personal safety, inclement weather associated with the storm could trigger localized business, transport, and utility disruptions. Floodwaters and debris flows could render some bridges or roadways impassable, impacting overland travel in and around affected areas. Areal flooding in urban locations could also result in severe traffic congestion. Heavy rain and low visibility may trigger flight disruptions at regional airports.

Disruptions triggered by inclement weather and resultant hazards, such as flooding, could persist well after weather conditions have improved. If there is severe damage to infrastructure, repair or reconstruction efforts may exacerbate residual disruptions.

Health
Stagnant pools of water during and after flooding increase the incidence of insect- and waterborne diseases, such as dengue fever, cholera, and malaria. The threat of these disease outbreaks is usually elevated in major urban centers' low-income or underdeveloped areas due to incomplete or open sewer lines. The latent threat of waterborne contaminants from inundated industrial sites cannot be discounted; exposure to raw sewage and other hazardous materials mixed with floodwaters poses a serious health threat.

Advice

Activate contingency plans in areas where officials forecast adverse weather conditions. Heed any evacuation orders that may be issued. Use extreme caution in low-lying coastal areas and near streams, creeks, and other waterways due to the high potential for severe flooding and storm surge. Stockpile water, batteries, and other essentials in advance. Charge battery-powered devices when electricity is available; restrict the use of cellular phones to emergencies only. Power down mobile devices when not in use. Keep important documents and necessary medications in waterproof containers. Observe strict food and water precautions, as municipalities could issue boil-water advisories following flooding events. Take precautions against insect- and waterborne diseases in the coming weeks.

Resources

Joint Typhoon Warning Center (JTWC)
Japan Meteorological Agency (Japanese)
Korea Meteorological Administration (Korean)