Ike's Winds, More Detail

Jeff Masters of the Weather Underground observes of the winds of Hurricane Ike.

Hurricane Ike made a direct hit on Galveston, Texas this morning at 3 am EDT as a top-end Category 2 hurricane with 110 mph winds. Although only rated a Category 2 storm, Ike carried a storm surge characteristic of a Category 4 hurricane to shore.

• Houston Hobby Airport on the south side of town recorded winds of 75 mph, gusting to 92 mph, at 6 am CDT today. The winds likely were higher, but the anemometer failed.
• Houston Intercontinental Airport on the north side of town recorded top winds of 56 mph, gusting to 70 mph.
• Eagle Point on Galveston Bay, at the northern end of Texas City, recorded sustained winds of 68 mph, gusting to 87 mph, at 1:34 am CDT.
• Top winds measured at Galveston Pleasure Pier were 60 mph.

Although Ike caused heavy damage by flooding Galveston with a 12-foot storm surge, the city escaped destruction thanks to its 15.6-foot sea wall (the wall was built 17 feet high, but has since subsided about 2 feet). The surge was able to flow into Galveston Bay and flood the city from behind, but the wall prevented a head-on battering by the surge from the ocean side. Galveston was fortunate that Ike hit the city head-on, rather than just to the south.

Despite Ike's rated Category 2 strength, the hurricane is much larger and more powerful than Category 5 Katrina or Category 5 Rita. The storm surge from Ike could rival Katrina's, inundating a 200-mile stretch of coast from Galveston to Cameron, Louisiana with waters over 15 feet high. This massive storm surge is due to the exceptional size of Ike. The diameter of Ike's tropical storm and hurricane force winds are 550 and 240 miles, respectively. For comparison, Katrina numbers at landfall were 440 and 210 miles, respectively.

Ike's highest storm surge occurred about 50 miles to the northeast of Galveston, over a lightly-populated stretch of coast. Galveston was also lucky that Ike did not have another 12-24 hours over water. In the 12 hours prior to landfall, Ike's central pressure dropped 6 mb, and the storm began to rapidly organize and form a new eyewall. If Ike had had another 12-24 hours to complete this process, it would have been a Category 4 hurricane with 135-145 mph winds that likely would have destroyed Galveston.

In summary,

• winds inland were not that strong, minimal Cat 1
• winds at sea were strong, Cat 2, and wide spread, 240 miles,
• the resulting storm surge was equal to a Cat 4 or 5
• if it has delayed in coming ashore, it would've been much worse

In light of this, I'm especially grateful that all that I experienced was a disrupted schedule at home and work for 11 days.