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Posted at 10:30 AM ET, 07/28/2009

My Dangerous Encounter With Hurricane Katrina

By Capital Weather Gang

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By Dr. Gregory Postel, Tropical Weather Expert


Satellite image of Hurricane Katrina on Aug. 25, 2005. Courtesy NOAA.

Several days before Hurricane Katrina came ashore along the Gulf Coast in August 2005, I made preparations to intercept its landfall.

At the time I decided to drive the thousand or so miles from Kansas City, Katrina was a Category 2 storm (winds 96-110 mph) on a path toward coastal Louisiana. I figured such conditions would provide a rigorous test for the weather instruments I had installed on my car, and yet still allow me to send any relevant meteorological information I could gather to friends of mine who were hurricane researchers with the National Oceanic and Atmospheric Administration.

Unfortunately, the attempt to observe and record Katrina's landfall nearly ended tragically for the group I traveled with.

Keep reading for an inside look at Hurricane Katrina's fury...

By the time we arrived in Slidell, La., on Aug. 27, it was clear that Katrina was going to be no ordinary hurricane. The storm's winds had strengthened to near 115 mph (borderline Category 2/3), and the atmosphere over the Gulf was favorable for further strengthening. Moreover, the storm's anticipated track crossed directly over an isolated pool of deep warm water.


Image shows pool of warm water near the center of the Gulf of Mexico on Aug. 28, 2005, as well as the history of Hurricane Katrina's track and strength. Courtesy NASA.

These "warm-core eddies," as they are known technically, are notoriously associated with the rapid strengthening of tropical cyclones. Such was the case this time around. Katrina's trek over the warm-core eddy helped trigger explosive development in a very short period of time. By noon on the 28th, Katrina attained its peak Category 5 intensity of about 172 mph around 170 miles southeast of the mouth of the Mississippi River. The wind field also expanded during the rapid intensification phase. Late that day, tropical storm-force winds were measured 200 miles from the center, and hurricane-force winds extended out roughly 90 miles.

Considering these remarkable developments, our team decided to relocate further east for safety reasons, and yet still remain near a secondary ring of locally maximized winds. We found a spot near Pascagoula, Miss., and set up our base there late on the 28th. Five miles from the Gulf, we assumed the storm surge was a minimal threat, especially at a GPS-measured elevation over 16 feet.


A hotel roof collapses around my car.

As Katrina neared the coast early the next morning, weather conditions over our area deteriorated in a manner consistent with a major hurricane's approach. Sudden bursts of wind and rain came with increasing frequency and intensity. One of the stronger rainbands, accompanied by wind gusts over hurricane force, caused the roof of a hotel to collapse around my car.

The sturdy sensors mounted atop my vehicle, seen poking through the fallen roof, may have actually saved it from complete destruction. Shortly after we extracted my car from the site, Gulf of Mexico water began lapping at our feet. Wait, what? Five miles inland and 40 miles from the storm's center? Within minutes, the water was 1-2 feet deep everywhere and rising. With little time to think, we instinctively fled inland as carefully as possible along flooded roads and through a dangerous maze of 100 mph wind gusts, torrential rain and falling trees. Had we not left immediately, it's quite possible the storm surge would have stranded us there for days.

After I returned home, incredibly fatigued and certain I would never intercept a landfall again, I surveyed data collected from Katrina and found some surprising results. According to the National Hurricane Center, the storm surge was 17-22 feet along the eastern half of the Mississippi coast, roughly from Gulfport to Pascagoula. It appears to have penetrated at least six miles inland in many portions of coastal Mississippi and up to 12 miles inland along bays and rivers.

I was unable to measure wind directly after the roof failure destroyed my anemometer (and nearly my car). But data accumulated by the Florida Coastal Monitoring Program (FCMP) and by the Jackson County Emergency Operations Center (EOC) suggest that maximum sustained winds at our location were in the 75-80 mph range with gusts over 100 mph. A tower monitored by FCMP at the nearby Trent Lott airport recorded a top gust of 105 mph and a minimum pressure of 978 mb. A peak gust to 124 mph was reported in Pascagoula at the Jackson County EOC. The documentation provided by NHC suggests that similar wind conditions were likely experienced all the way west to New Orleans.

These findings highlight the asymmetrical nature of the meteorological hazards that accompanied Katrina during landfall. Owing to its intake of continental (non-tropical) air, Katrina began rapidly weakening at least 12 hours before landfall (as many Gulf storms do). As a result, wind speeds experienced at most locations along the heavily damaged coast were generally relatively low -- in the Category 1-2 range -- compared to what many expected.

On the other hand, the storm surge was nearly unprecedented, characteristic of a Category 5 impact. According to NHC, buoy 42040, operated by the National Data Buoy Center (NDBC) and located about 64 miles south of Dauphin Island, Ala., reported a significant wave height (defined as the average of the one-third highest waves) of 55 feet on the morning of the 29th, matching the largest significant wave height ever measured by an NDBC buoy. Apparently, Katrina maintained the agitated sea state of a Category 5 hurricane long after its winds were more like a Category 1 or 2 storm.

My experience with the Katrina landfall never did stop me from intercepting hurricanes. It did, however, change the way I prepare for them.

Dr. Gregory Postel is the lead meteorologist for a weather-risk management firm in Overland Park, KS. He earned his Ph.D. in atmospheric sciences from the University of Wisconsin-Madison, and conducted research on factors leading to the development of tropical cyclones. He's an avid hurricane chaser and has been known to drive more than a thousand miles to intercept land-falling hurricanes.

By Capital Weather Gang  | July 28, 2009; 10:30 AM ET
Categories:  Tropical Weather  
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Comments

Greg, that's an interesting account, which vividly shows how far inland the storm surge actually reached. What were your research goals for the Katrina trip, and any other hurricane intercepts you have made? What were you trying to shed light on exactly, or is hurricane chasing a bit more of a thrill than a scientific expedition?

Posted by: Andrew-CapitalWeatherGang | July 28, 2009 10:58 AM | Report abuse

Hopefully we won't have this issue during the current El Nino-influenced hurricane season which is yet to begin.

Posted by: Bombo47jea | July 28, 2009 11:45 AM | Report abuse

Andrew,

There is much to learn about the evolution of hurricanes near landfall. The data I can collect -though I don't have the proper funding/equipment etc. to officially observe and record conditions- hopefully adds something to the puzzle. There is also no doubt I am highly curious about what happens during landfall. And there is always a chance that what I find might lead me down a scientific/academic pursuit of the problem. But to answer your question ... no, it's not a thrill-seeking adventure.

Posted by: gregpostel | July 28, 2009 12:14 PM | Report abuse

Greg, thanks for the response. You might want to tag along someday, if possible, with the crew from Texas Tech's "sticknets" team. I was with them during VORTEX2, and they do some really interesting work getting datasets at hurricane landfall locations, occasionally working with Josh Wurman's mobile Doppler radar team. http://www.atmo.ttu.edu/TTUHRT/WEMITE/sticknet.htm

Posted by: Andrew-CapitalWeatherGang | July 28, 2009 1:28 PM | Report abuse

The comments to this entry are closed.

 
 
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