I looked back through the last few pages to see if this had been posted, and couldn't find it...sorry if its a duplicate.
Category 2 Ike is larger and more powerful than Katrina Posted by: JeffMasters, 11:32 AM EDT on September 11
Hurricane Ike's winds remain at Category 2 strength, but Ike is a freak storm with extreme destructive storm surge potential. Ike's pressure fell rapidly last night to 944 mb, but the hurricane did not respond to the pressure change by increasing its maximum winds in the eyewall. Instead, Ike responded by increasing the velocity of its winds away from the eyewall, over a huge stretch of the Gulf of Mexico. Another very unusual feature of Ike is the fact that the surface winds are much slower than the winds being measured aloft by the Hurricane Hunters. Winds at the surface may only be at Category 1 strength, even though Ike has a central pressure characteristic of a Category 3 or 4 storm. This very unusual structure makes forecasting the future intensity of Ike nearly impossible. The possibilities range from a Category 1 storm at landfall--as predicted by the HWRF model--to a Category 4 storm at landfall, as predicted by the GFDL.
Ike is now larger than Katrina was, both in its radius of tropical storm force winds--275 miles--and in it radius of hurricane force winds--115 miles. For comparison, Katrina's tropical storm and hurricane force winds extended out 230 and 105 miles, respectively. Ike's huge wind field has put an extraordinarily large volume of ocean water in motion. When this swirling column of water hits the shallow waters of the Continental Shelf, it will be be forced up into a large storm surge which will probably rival the massive storm surge of Hurricane Carla of 1961. Carla was a Category 4 hurricane with 145 mph winds at landfall, and drove a 10 foot or higher storm surge to a 180-mile stretch of Texas coast. A maximum storm surge of 22 feet was recorded at Port Lavaca, Texas. Despite the fact that the center of Carla hit over 120 miles southwest of Houston, the hurricane drove a 15-foot storm surge into the bays along the south side of the city. I don't expect Ike will reach Category 4 strength, thus its maximum surge is not likely to reach the extreme values above 20 feet seen in Hurricane Carla. Like Carla, though, Ike will probably inundate a 180-mile stretch of Texas coast from Port O'Connor to just north of Galveston with a 10-15 foot storm surge. This will occur even if Ike is a Category 1 storm at landfall. The latest experimental storm surge forecast From NOAA's SLOSH model (Figure 1) shows a 10% chance that Ike's storm surge will exceed 15-21 feet at Galveston. The Galveston sea wall is 17 feet high, so may get overtopped.
The amount of water Ike has put in motion is about 50% greater than what Katrina did, and thus we can expect Ike's storm surge damage will be similar to or greater than Katrina's. The way we can estimate this damage potential is to compute the total energy of Ike's surface winds (kinetic energy). To do this, we must look at how strong the winds are, and factor in the areal coverage of these winds. Thus, we compute the Integrated Kinetic Energy (IKE) by squaring the velocity of the wind and summing over all regions of the hurricane with tropical storm force winds or higher. This "Integrated Kinetic Energy" was recently proposed by Dr. Mark Powell of NOAA's Hurricane Research Division as a better measure of the destructive power of a hurricane's storm surge than the usual Category 1-5 Saffir-Simpson scale. For example, Hurricane Katrina hit Mississippi as a strong Category 3 hurricane, yet its storm surge was more characteristic of a Category 5 storm. Dr. Powell came up with a new scale to rate potential storm surge damage based on IKE (not to be confused with Hurricane Ike!) The new scale ranges from 1-6. Katrina and Wilma at their peaks both earned a 5.1 on this scale (Figure 2). At 9:30am EDT this morning, Ike earned a 5.6 on this scale, the highest kinetic energy of any Atlantic storm in the past 40 years.
http://www.wunderground.com/blog/JeffMa ... amp=200809
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