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Super Typhoon Haiyan in Tacloban City, Philippines

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Thursday, 3 April 2014
Golden Ballroom (Town and Country Resort )
Josh Morgerman, iCyclone.com, West Hollywood, CA

On the morning of 08 November 2013, Super Typhoon Haiyan crossed the Leyte coast of the Philippines.

Estimates of the 1-minute winds at landfall from different agencies (JMA, JTWC, PAGASA) ranged from 140 to 170 kt. The north eyewall passed directly over Tacloban City (pop. 221,000), making it the largest population center to experience a direct hit from a Category-5 cyclone (on the Saffir-Simpson Hurricane Wind Scale) in at least two decades.

Official data from the landfall region were sparse to nonexistent. Fortunately, the iCyclone team collected continuous, quality-controlled data and time-stamped video footage in downtown Tacloban City during the entire passage of the cyclone's core. What emerges is a complete record of the event—with interesting conclusions:

• The cyclone was quite small. Contrary to media reports, the aerial extent of the storm was narrow, and damaging winds were confined close to the center. Furthermore, the RMW was narrow enough to miss the downtown area, probably by a few miles.

• The storm surge was tremendous, fast-moving, and short-duration. Inundation at our location suggests the surge was possibly as high as 30 ft—and yet it arrived very suddenly and only lasted at our location for 1-1.5 hours.

• The pressure gradient in the cyclone's core was extremely steep. At out location—in the north eyewall, about 15 n mi from the center of the eye—two devices recorded low pressures of ~960 mb as the center passed to the south. At this time, the cyclone's central pressure was most certainly lower than 910 mb.

Supporting the above conclusions will be iCyclone's:

• Air-pressure traces from two calibrated devices.

• Storm-surge observations.

• Detailed event chronology (reconstructed from time-stamped video footage).

• Time-stamped video stills.

Supplementing these will be USGS elevation data, PAGASA radar imagery, and all available PAGASA data (for example, incomplete air-pressure data from Guiuan and the Tacloban City Airport).