Tropical Storm Aere (Bebeng)

Meteorological Report:
Meteorological REPORT on AERE (Bebeng)

On May 7, 2011, the Philippines were struck by cyclone Aere (Bebeng), the second cyclone of the season and the first to hit the Philippines this year. After gaining strength over the open ocean since May 6 and subsequently hitting the central eastern islands, it now moves northwards along the coast. Wind speeds of Aere are comparatively low, giving the cyclone enough time to shed massive amounts of rain over the affected areas. Up to now, Aere has caused 24 confirmed casualties; more than 400,000 persons were affected (as reported by the National Disaster Risk Reduction & Management Council, NDRRMC). The estimated agricultural damages due to Aere amount to PhP 360,000,000, almost 8500 houses were damaged.

At DHI, we closely follow the dramatic events that take so many lives and livelihoods. In an attempt to offer the best possible support to the affected population and commissioned by Munich Re, one of the world's leading reinsurance providers, DHI set up a real-time monitoring system of wind and rain all over the Philippines. Based on this monitoring system, MunichRe developed an insurance solution to protect the low-income population of the affected areas against the effects of such natural catastrophes and allow for the necessary reconstruction works. Learn more about DHI'S product

In 28 municipalities, all of them situated on Samar, our data revealed an event of the worst category, a so-called 20 year event (that is, you only get that much rainfall every twenty years or even more rarely). In Catarman (Northern Samar), for example, 24hr-rainfall on May 8th was 377,4mm as reported by NDRRMC, which matches well with the 397mm reported by DHI satellite data. In that region, 1300 persons in 8 BARANGAYS were affected by Aere.


Figure: DHI's real-time monitoring provides up-to-date information on wind and rainfall all over the Philippines. In the right panel, events are categorized according to their recurrence interval (10, 15 or 20 years). Heavy rain on May 7 is clearly visible on the left panel, triggering an insurance payout in the regions indicated in the right panel.


OVER THE PHILIPPINES (7 to 10 May, 2011)

  • A Tropical Depression was detected late Friday evening May 6, 2011, in the western Pacific Ocean east of Visayas, near the Central -Eastern coasts of Philippines.
  • Saturday morning, May 7, the Tropical Depression was located, based on satellite and surface data, at 180km East of Catarma, northern Samar. The depression eventually developed into a more harmful Tropical Storm* with maximum sustainable winds of around 55Km/h near the centre, moving north-west at around 13km/h.
  • As of Sunday, May 8, around 10:00am, the Tropical cyclone, Aere (Bebeng), made its first landfall over Northern Catanduanes, Aurora, close to Bicol region. It then continued to move towards the area of Quezon-Aurora with maximum sustainable winds of 93km/h and gusts of 120km/h.
  • Fortunately, as of Monday, May 9, the Tropical Storm started to weaken after having shown maximum sustainable winds of 85km/h near the centre of the storm with gusts of up to 100km/h. Aere (Bebeng) still made its second landfall over northern Casiguran.
  • Due to the pressure atmospheric situation, Aere (Bebeng) continued its NNW-ward track during the night of Monday before starting to move away from the Philippines re-curving towards a North Northeast direction. Tuesday morning, May 10, at 4:00am the centre of the still "Tropical Storm" was estimated at 120km southeast of Basco, Batanes, one of the Northern islands of the Philippines, and moving NNE at a faster speed (17km/h). Aere (Bebeng) had maximum sustainable winds of 65km/h near the centre and gustiness of up to 80km/h.
  • During the following 24 hours, the Tropical Storm continued to move away from the Philippines, maintaining however its strength. Wednesday morning (2:00am), May 11, the centre (eye) of Aere (Bebeng) was estimated to be at 450km Northeast of Basco, Batanes. Aere (Bebeng) moved Northeast at a speed of 24km/h in the direction of the Okinawa islands in Japan. Recent information from The National Disaster Risk Reduction & Management Council reports maximum sustainable winds of 65km/h near the centre and gust of up to 80km/h. At 11:00am, Aere (Bebeng) accelerated and exited outside the Philippine Area of Responsibility.

*AERE (BEBENG) is a strong Tropical Storm on the Saffir-Simpson Tropical Cyclone Scale. Tropical Storm Force Winds (62-117 km/h) extend outward up to 220 km (120 nautical miles) from the centre. AERE is an average-sized tropical cyclone with a diameter of 405 km (220 nautical miles).

DHI's system (see for more details), was able to track Aere's (Bebeng) precipitations over the Philippines during the entire tropical storm's cycle. DHI's rainfall monitoring system emitted its first alert on Saturday, May 7, according to the arrival of the tropical cyclone.

Based on the precipitation data received from the TRMM satellite, DHI's system calculated the actual extreme precipitation and determined the event categories over the regions affected by the tropical storm.

DHI's images below (1 and 2) show the areas that have received extreme precipitation on May 7 and the event category that corresponds to each municipality. On that same day, the National Disaster Risk Reduction & Management Council emitted its first warnings and damages reports for the same geographical region (Eastern Samar, Samar, Northern Samar, Albay and Camarines) ( link to initial report of NDRRMC).

Rain Fall

Figure 2: Rainfall and event category details of affected municipalities on the 7th May 2011.