Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 5:11 PM GMT on September 13, 2008
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. The destructive power of Ike's storm surge rated a 5.0 on a scale of 0 to 6 just before landfall, according to the experimental Integrated Kinetic Energy (IKE) product of NOAA's Hurricane Research Division. This is about the same destructive potential Katrina had at landfall.
Figure 1. Radar image of Ike shortly after landfall. The eye passed directly over Galveston, and along the east side of Houston.
Galveston is not destroyed
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. 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. The GFDL model was consistently advertising this possibility, and it wasn't far off the mark. It was not clear to me until late last night that Ike would not destroy Galveston and kill thousands of people. Other hurricane scientists I conversed with yesterday were of the same opinion.
Figure 2. Radar images of Ike on Friday, 9/12/08. In the left image, we see Ike as it appeared Friday afternoon, with no eyewall and relatively weak echoes. The pressure of the storm was 958 mb. By Friday night (right panel), Ike had begun to form an eyewall, and the echoes had become much more intense. Ike had a pressure of 952 mb at this time.
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. The airport measured a central pressure of 960 mb as the eye passed just to the east. 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, and the station recorded a pressure of 952 mb as the eye of Ike passed over. Top winds at Sabine Pass on the Louisiana border were a sustained 70 mph. Much higher winds undoubtedly occurred on Galveston Island and nearby coastal areas, but the anemometers failed before these winds were recorded. An experimental wind analysis done by NOAA's Hurricane Research Division suggests that Category 2 force winds probably only affected a 40-mile stretch of coast northeast of Galveston. There were no weather stations there to record these peak winds. Category 2 winds undoubtedly occurred at the tops of Houston's skyscrapers, as well.
Figure 3.water levels on the Neches River in Beaumont, TX (top) on the Louisiana border increased by 6 feet as Ike's surge progressed upriver. The river has reversed its direction of flow, as seen in the negative river discharge numbers (bottom). Winds peaked at 60 mph at this location. Image credit: U.S. Geological Survey.
Ike's storm surge
Tide gauge data suggests that a storm surge of 12-14 feet affected the region from Galveston to the Louisiana border. Higher storm surges in excess of 15-20 feet likely occurred in Galveston Bay and northeastward, as inferred by comparing the observed surge values we have with the 11 pm forecast surge values (Figure 4). At 10am this morning, the National Weather Service was reporting water levels of 12 feet in the Houston Ship Channel, and 10-14 feet in Galveston Bay. In Port Arthur, TX, on the Louisiana border, the surge reached 11 feet, and did not overtop their 14.5 foot high sea wall, sparing the city and its oil refineries from the major flooding that was feared.
Figure 4. Predicted storm surge from Ike issued shortly before the hurricane came ashore. There was a 10% chance given that the actual surge would excede the forecast heights shown here. The actual storm tide heights (surge plus the tide, shown as red numbers) show that Ike's surge stayed about 2 feet below this "10% exceedance" height. Image credit: NOAA.
My sincere best wishes and prayers go to everyone affected by this historic storm.
A night on Galveston Island
Wunderground member CycloneBoz rode out Ike in a parking garage in Galveston. Here's his report from this morning:
This is CycloneBoz, live from the southern eyewall of Hurricane Ike.
What a storm! My wind gauge read 110 mph
In the car, I'm being bucked like riding a bronco! Easily, winds now still over 100 mph!
I'm on the 2nd floor of the Hotel Galvez parking garage. I have shot some incredible video. I'm chomping at the bit to edit it...and I think I'm going to have time to do that here...because no one is going to get off this island anytime soon.
The surge was an east to west event at midnight. Now, the surge is a west to east event. Flooding everywhere. Multiple fires! There was even a fire out at sea on one of the piers in front of the garage during the first part of the storm.
Massive destruction. Surprisingly, though, a lot of the houses are keeping their roofs! But the people inside are sure worried!
I yelled across the street during the incredible eye event to a lady whose first floor was flooded. Everyone there was okay, but I could tell she was crying. She was scared to death.
As my car rocks wildly as I sit beneath tons of concrete, I have to admit......I'm a bit on edge myself.
Tropical disturbance approaching the central Bahamas
An area of disturbed weather (91L) is located about 300 miles east of the central Bahamas, and is moving west-northwest at 10-15 mph. Satellite loops show that 91L's heavy thunderstorms have decreased significantly overnight, thanks to dry air and wind shear from an upper-level low pressure system to the west. There is no evidence of a surface circulation.
Shear is expected to remain 10-20 knots though Monday, which may allow some gradual development. None of the models are developing 91L, but the central Bahamas can expect heavy rain and strong gusty winds Saturday. These conditions may spread to the western Bahamas by Sunday and the east coast of Florida by Sunday night. NHC is giving this disturbance a low (<20% chance) of developing into a tropical depression by Monday.
Tropical disturbance in the middle Atlantic
There is another area of disturbed weather (92L) midway between Africa and the Lesser Antilles islands. This disturbance is under about 20 knots of wind shear, and is suffering from dry air to it west. NHC is giving this system a low (<20% chance) of developing into a tropical depression by Monday. Wind shear may drop over the disturbance on Monday, so we'll have to keep an eye on it.
I'll have a new blog Sunday.
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