Wednesday, September 17, 2008

Comparing Hurricane Ike With The 1900 Galveston Hurricane

Left: Surface weather analysis of the 1900 Galveston hurricane on September 8, just before landfall.


As bad as Hurricane Ike has been for Galveston, it could have been a lot worse.

In general, in the Northern Hemisphere, the biggest storm surge is to the right of the hurricane eye. Hurricane Ike's eye passed over Galveston, with the eye's center passing a short distance east of the city, and the storm surge caused problems everywhere, but particularly to the east, towards Port Arthur and Louisiana. Unfortunately, the storm surge was high enough to overtop the Galveston Seawall, but at least the island wasn't swept free of buildings altogether.

The eye of the 1900 hurricane crossed the coast southwest of Galveston, so Galveston took the full brunt of that storm's surge. And the 1900 hurricane was more powerful: Category 4 (120 mph+; 935.7 mb), stronger than Ike's Category 2 (110 mph; central pressure of 952 mbar).

So, in a way, this time, Galveston was lucky.

Which reminds me of what George Orwell wrote in his personal account of the Aragon front of the Spanish Civil War, in "Homage To Catalonia". Orwell was shot through the neck, and he suffered terribly, but because the bullet missed the carotid artery and the spine, the medics and the nurses kept telling him how lucky he was. Orwell said that, despite managing to survive, he didn't feel lucky at all.

Left: NY Times' graphic showing the path of Hurricane Ike's eye.

Regarding Ike, Wikipedia notes:
Over the next two days, Ike maintained a steady course towards Galveston and Houston. It increased only slightly in intensity to 110 mph (177 km/h) - the high end of Category 2 - but exhibited an unusually large wind field. As it approached the Texas coast, the inner structure and eyewall became more organized.

Ike made U.S. landfall at Galveston, Texas, on September 13 at 2:10am CDT (07:10 UTC), as a Category 2 hurricane with winds of 110 mph (177 km/h) and a central pressure of 952 mbar (28.11 inHg). The 2:00 am NHC advisory cited tropical storm and hurricane force winds extending 275 miles (445 km) and 120 miles (190 km), respectively, from the center.

Left: Radar image of Hurricane Ike at landfall. HGX Radar, Base Reflectivity, 1:07am CDT.


Regarding the 1900 Galveston Hurricane, Wikipedia notes:
At the time of the 1900 storm the highest point in the city of Galveston was only 8.7 ft (2.7 m) above sea level. The hurricane had brought with it a storm surge of over 15 ft (4.6 m), which washed over the entire island. The surge knocked buildings off their foundations and the surf pounded them to pieces. Over 3,600 homes were destroyed and a wall of debris faced the ocean. The few buildings which survived, mostly solidly-built mansions and houses along the Strand District, are today maintained as tourist attractions.

The highest measured wind speed was 100 mph (160 km/h) just after 6 p.m., but the Weather Bureau’s anemometer was blown off the building shortly after that measurement was recorded. The eye passed over the city around 8 p.m. Maximum winds were estimated at 120 mph (190 km/h) at the time, though later estimates placed the hurricane at the higher Category 4 classification on the Saffir-Simpson Scale. The lowest recorded barometric pressure was 28.48 inHg (964.4 hPa), considered at the time to be so low as to be obviously in error. Modern estimates later placed the storm’s central pressure at 27.49 inHg (930.9 hPa), but this was subsequently adjusted to the storm's official lowest measured central pressure of 27.63 inHg (935.7 hPa).

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