Typhoon Haiyan

Pre-Landfall 1 | Summary
Posting Date: November 7, 2013, 12:45:00 PM

Storm signal 4, heralding winds of more than 185 km/h, has been raised in Samar, Leyte, Masbate, Biliran province, extreme northern Cebu, Bantayan Island, Capiz, Aklan, and northern Antique as Typhoon Haiyan approaches the central Philippines. Yolanda, as it is known locally, is the 30^th tropical cyclone of 2013, according to the Japan Meteorological Agency (JMA), and will make landfall in the Philippines in the next two hours. Clouds from the storm system are already affecting two-thirds of the country.

Forecast Track and Intensity

At 895 mb, with 10-minute sustained wind speeds of 231 km/h (143.5 mph) and gusts as high as 324 km/h (200 mph), Haiyan is the strongest tropical cyclone of 2013 globally thus far. It will be the strongest to make landfall anywhere in the world since Megi (2010) made landfall in the Philippines at 885 mb and 10-minute sustained wind speeds of 231 km/h (143.5 mph), according to the JMA. Haiyan’s wind speeds are the second highest ever observed in the Northwest Pacific basin, and its central pressure is tied as the 20^th lowest.  

Haiyan is in a very conducive environment for tropical cyclone development, with sea surface temperatures (SSTs) above 30°C (86°F)—26°C (78.8°F) is generally considered to be the minimum threshold for maintaining cyclone activity—ample low-level moisture, and low wind shear. As a result, Haiyan is not forecast to weaken prior to landfall. Wind will be the primary cause of damage, but precipitation-induced flooding could occur locally. Precipitation in the wake of the storm is on the order of 150-250 mm (about 6-10 inches) according to the Tropical Rainfall Measuring Mission (TRMM).   

Haiyan is forecast to weaken slightly as it passes through the central Philippines but will continue moving west-northwest along the southern periphery of the subtropical ridge. After exiting into the South China Sea, Haiyan is forecast to continue to weaken somewhat as it experiences slowly decreasing SSTs before making landfall in Vietnam.  According to the JMA, the forecast intensity when the storm reaches Vietnam is 930 mb, with 10-minute sustained wind speeds of 185 km/h (115 mph), with gusts as high as 259 km/h (161 mph). 

Hazards and Preparations

As well as devastating winds, the storm will bring storm surge to the eastern coast of southern Luzon and the Samar islands, and deposit heavy rain across a wide swath of the central Philippines as it passes approximately 386 km (240 miles) to the south of Manila. This region, recently drenched by a tropical cyclone and still reeling from the 7.1-magnitude earthquake that struck the island of Bohol in October, is home to about 10 million people. More than 30 provinces across the country have been alerted to prepare for possible flash floods and landslides.

President Benigno Aquino III has ordered government agencies to aim for zero casualties as residents and local government units prepare for the worst. Relief goods and emergency services have been positioned, and thousands of people in vulnerable areas have been evacuated. Schools have closed and airlines have canceled flights.

Exposure at Risk

Typhoon Haiyan will impact a region of the Philippines that is largely rural and agricultural, although some cities are in the path of the storm. Given that the region is generally less urbanized and less accustomed to typhoons, construction types and standards are lower than those in the northern Islands. While reinforced masonry structures are typical, light materials—such as wood frame with galvanized iron and aluminium roofs—are frequently used for residential buildings in these rural areas making them more vulnerable when compared with those in neighboring Manila, Hong Kong, or Taiwan. Still, given that insurance penetration in this area is around 10% to 20%, insured losses are not expected to be significant as a result of this event.

The AIR tropical cyclone team will continue to monitor Typhoon Haiyan and provide updates as necessary.

Pre-Landfall 1 | Downloads
Posting Date: November 7, 2013, 12:45:00 PM