Hurricane Katrina Service Assessment

High Water Mark Collection for Hurricane Katrina in Alabama

National Weather Service, Mobile-Pensacola

Extremely Powerful Hurricane Katrina leaves a Historic Mark on the Northern Gulf Coast

A Killer Hurricane Our Country Will Never Forget –

As Katrina set new minimum central pressure records while approaching the U.S. North Central Gulf Coast on Sunday, 28 August 2005, the storm finally made the dreaded and final northward turn as it moved towards Link to Coastal Aerial Photossoutheastern Louisiana. Katrina was a large storm with a distinct eye. Earlier that day, Katrina reached a minimum central pressure of 902 mb (at the peak), ranking 4th lowest on record for all Atlantic Basin hurricanes. Hurricanes Rita and Wilma of 2005 later fell to lower minimum central pressures that year. The storm had clearly become a killer having intensified to a category five (Saffir-Simpson). The central pressure at landfall was 920 mb, which ranked 3rd lowest on record for US-landfalling storms behind Camille (909 mb) and the Labor Day hurricane that struck the Florida Keys in 1935 (892 mb). The storm continued moving in a north-northeast fashion and made a second landfall over Hancock County, Mississippi, or very near the mouth of the Pearl River. Hurricane Katrina was one of the strongest storms to impact the US Coast during the last 100 years and most likely will stand as our nation’s costliest natural disaster to date. With sustained winds of 140 mph (a strong category 4 hurricane) during landfall and possessing a minimum central pressure of 920 mb (third lowest on record) at landfall, Katrina caused hundreds of deaths, prolonged human suffering, and widespread devastation along portions of the US Gulf Coast.

There have been only 3 storms with stronger sustained winds when they made landfall in the U.S.:

· The Labor Day Hurricane, Florida Keys, September 2, 1935, Category 5, 892 mb
· Hurricane Camille, Mississippi, August 17, 1969, Category 5, 909 mb
· Hurricane Andrew, Southeast Florida, August 24, 1992, Category 5, 922 mb

The record for the highest wind speed at landfall belongs to Hurricane Camille (1969), which produced wind gusts of over 200 mph and an estimated sustained wind speed of 190 mph at landfall. In Katrina (2005), landfall wind speeds at Grand Isle, Louisiana were approximately 140 mph with a central pressure of 920mb - the 3rd lowest on record for a landfalling Atlantic storm in the US. The above information is courtesy of the National Climatic Data Center (NCDC).

After the storm continued plowing inland into Mississippi during the afternoon of the 29th, Katrina left a wake of pure devastation that will never be forgotten. The loss of life and property damage was heightened by breaks in the levees that separate New Orleans from Lake Pontchartrain. At least 80% of New Orleans was under flood waters on August 31st (source NCDC). Americans watched in awe as thousands were stranded on roof tops and US Coast Guard helicopter rescues were performed.

Although much will be written on the effects associated with this storm, this document will remain focused on Katrina's impacts over inland southeastern Mississippi, southwestern Alabama and the extreme northwestern Florida Panhandle. Below are some of the regional impacts

· STORM SURGE

Known for her killer storm surge, Katrina’s highest surge values were found in a zone from just east of the eye near Bay St. Louis, MS eastward to the northern reaches of Mobile Bay. The Mobile State Docks measured the highest storm surge value of 11.45 feet, while the lowest was 4.1 feet in Santa Rosa Sound, Florida. It is known that the storm surge was as high as 12-14 feet range in Bayou La Batre, Alabama and was likely closer to 20 feet immediately along the Mississippi-Alabama border. Many homes were completely engulfed by Katrina’s surge in Bayou La Batre. The surge in Mobile Bay led to inundation of downtown Mobile causing the imposition of a dusk-to-dawn curfew. The Mobile State Docks surge value of 11.45 feet was extremely close to being the highest value ever recorded (previous record of 11.60 feet that occurred on 5 July 1916). The exact location and degree of accuracy of the 1916 record surge value is unknown. Table 1 yields a complete listing of surge values. No lives were lost due to storm surge in Mobile and Baldwin Counties. Long lead warning times were given by the NWS Offices in both Mobile, Alabama and New Orleans, Louisiana as to how high the surge would be. As early as two days before landfall, the local NWS Office in Mobile, Alabama issued a 725 PM CDT Hurricane Local Statement that foretold of the historic storm surge values that would be associated with Hurricane Katrina. Of specific mention was storm surge values of 8 to 12 feet well east of Katrina's center. Subsequent Hurricane Local Statements continued to provide updated and very detailed information regarding the storm surge problem.


Table 1- Observed storm surge data
Note: Highest tides occurred on August 29, 2005
<Click here> for an area map depicting a portion of the following storm surge data.

Tide Gage
Time in UTC
Highest Tide in MSL
Mobile State Docks (MBRA1)
1848
11.45
USS Alabama (est.)
 
12.00
Dauphin Island (DAUA1)
1645
6.63
Dauphin Island (DPIA1)
1542
6.23
Perdido Pass (PPSA1)
1336
5.81
Pensacola (PENF1)
 
5.37
Destin (EPSF1)
1336
4.52
Santa Rosa Sound (FWLF1)
1654
4.10


· WIND

As previously mentioned, Katrina’s maximum landfalling windspeeds near Grand Isle, Louisiana were approximately 140 mph. As Katrina moved further northward and made her second landfall along the Mississippi and Louisiana border, the National Weather Service (NWS) WSR-88D single-Doppler radar in Mobile (KMOB WSR-88D) measured winds as high as 132 mph between 3000 and 4000 feet above ground level during the morning hours. It is estimated that eighty to ninety percent (approximately 104-119 mph) of the latter maximum wind speed value reached the ground. Tree damage in Stone County, MS was very similar to what Ivan produced in Atmore and Brewton. In the velocity loop ( <Click here> to see a velocity loop from 759 AM until 859 AM CDT) you will note the storm’s eye (labeled in the large white circle) is southwest of the region of maximum surface wind speeds. These measurements are winds flowing toward the KMOB WSR- 88D. The following colors indicate where the next highest velocity values begin (gray = 104 mph; brown = 109 mph; dark blue = 114 mph; cyan= 117 mph; green >127 mph). Table 2 contains observed sustained winds and maximum regional wind gusts.


Table 2- Sustained Winds and Maximum Wind Gusts
Note: All Wind Data Occurred on August 29, 2005

Location
Sustained Wind in Knots
Peak Wind Gust in Knots
Time of Gust in UTC
Mobile Regional Airport (KMOB)
57
72
1608
Brookley Field (KBFM)
58
73
1501
Destin (KDTS)
30
44
1727
Pensacola Airport (KPNS)
49
60
1451
Crestview (KCEW)
30
38
1842
Evergreen (KGZH)
32
42
2118
Eglin Air Force Base (KVPS)
33
46
1709
Mary Esther (KHRT)
38
52
1521
Pensacola Naval Air Station (KNPA)
49
62
1812
Eglin AFB (6 miles W of Mary Esther)
51
60
1452
Dauphin Island (DPIA1)
64
89
1542
Pensacola (WEAR-TV)
 
50
 
Mobile Bay (USS Alabama)
 
90
 
Holley Middle School, FL
 
40
 
Destin Middle School, FL
 
37
 
Wright Elementary School, FL
 
39
 
Semmes
 
57
 


· RAINFALL

The KMOB WSR-88D shows the greatest amount of rain fell east of Katrina’s eye and very close to the coast. A general 5-10 inches of rain fell with isolated amounts exceeding 12 inches. Rainbands extending well east of Katrina’s eye brought isolated rainfall totals of between three and five inches over portions of the extreme northwestern Florida Panhandle. In general, significantly lighter rainfall amounts (< 2 inches) fell east of a Camden, Alabama to Evergreen Alabama to Navarre Florida line. Table 3 contains regional rain gauge measurements.


Table 3- 48 h rainfall (in.) totals ending 1159 PM - August 29, 2005

Location
48 h rainfall (in.) totals ending 1159 PM - August 29, 2005
Mobile Regional Airport (KMOB)
3.80
Thomasville
3.17
Semmes
5.70
Pensacola (WEAR-TV)
3.06
Daphne
4.97
Philpot, FL
7.80
Milton
4.50
Molino
5.00
Oak Grove
6.00
6 hour total for Mobile Regional Airport (KMOB) - 1.43 inches ending at 1359 UTC August 29



Acknowledgements and Disclaimer: This page was created by Jeffrey Medlin (Science and Operations Meteorologist), Ray Ball (Information Technology Specialist) and Gary Beeler (Warning Coordination Meteorologist) with other contributions from various members of the NWS Mobile Alabama Staff. The National Weather Service in Mobile, Alabama reserves the right to update this summary as newer, and more accurate, information becomes available.


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