Radar showing northern eyewall of Super Typhoon Haiyan passing through Tacloban at 7 a.m. local time on November 8 (iCyclone)

The iCyclone chase team, which earned fame by sharing with the world harrowing first-hand accounts of Super Typhoon Haiyan in Tacloban, has published the data it recorded during the storm. It reveals a storm that struck with sudden and excessive force and that, despite its short duration, overwhelmed and ultimately destroyed much of the Philippine city.

Haiyan’s storm surge “rose very suddenly and rapidly” and was estimated by the team – consisting of Josh Morgerman, James Reynolds, and Mark Thomas – to be between 20 and 30 feet high.

“The hotel [where we stayed] flooded to a depth of ~4 ft,” the iCyclone report, authored by Morgerman, says. “If the elevation at this location is truly 26 ft—as indicated by USGS [U.S. Geological Survey] —that suggests a storm surge of up to ~30 ft . It’s possible the elevation may have been as low as 15 ft, in which case, the surge was ~20 ft.”

These surge estimates are higher than those from other sources of around 13 feet.

Related: Typhoon and hurricane storm surge disasters are unacceptable

The storm’s damaging winds lasted “only a few hours-a short duration event compared with a typical tropical-cyclone passage” the report says, but they were nevertheless “very destructive.”

The iCyclone team recorded the storm’s pressure on two devices, both of which show a stunning, steep drop of about 40 millibars (mb) in 6 hours. The pressure tanked from roughly 1,000 mb at 1 a.m. on November 8 to around 960 mb just after 7 a.m. local time.

Chart of pressure with time (or barogram) in Tacloban during Super Typhoon Haiyan (iCyclone)

The minimum pressure recorded of 960 mb was more than 60 mb higher than the estimated minimum pressure at the storm’s center (895 mb according to the Joint Typhoon Warning Center), which passed about 15 nautical (n) miles (mi) south of Tacloban.

“The center was only ~15 n mi away at the time, suggesting an incredible gradient [of 4 mb per mile],” the report says.

Fur further reading, see the “preliminary” full iCyclone Chase Report for Haiyan (Yolanda) embedded below.


Disaster in Tacloban, Philippines: Chasers document “ghastly” scene from typhoon

Hurricane chasing: While most run from the storm, iCyclone seeks out its core

5 Questions For A Seasoned Storm Chaser Who Witnessed The Wrath Of Typhoon Haiyan (BuzzFeed)

Typhoon Haiyan weather data from iCyclone