National Weather Service, Mobile-Pensacola

Powerful Hurricane Ivan Slams the US Central Gulf Coast as an Upper Category-3 Storm


last updated:    Tuesday, 6 January 2005  (updated wind and storm surge information) 

   At 51 minutes after midnight on 16 September 2004, the northern Coastal Aerial Photos eyewall of powerful Hurricane Ivan (see landfall ) moved onto land near Gulf Shores, Alabama as an upper Category 3 hurricane (Saffir-Simpson Scale).  The official time of landfall was 202 AM CDT (ie. when the center of Ivan's eye crossed land). Bringing with it 130 mph surface winds and a historic storm surge, preliminary estimates show that the magnitude and extent of the damage and destruction over Baldwin County Alabama and Escambia and Santa Rosa counties of northwest Florida likely exceeded that of  both Hurricane Frederic (September 1979) and Hurricane Opal (October 1995).  Additionally, Hurricane Ivan may rival the magnitude of damage and destruction caused by the Hurricane of 1926 which ravaged the aforementioned counties east of Mobile Bay.  Hurricane Ivan caused a preliminary total of 13 deaths in the following counties combined:  Baldwin County, Alabama, Escambia County, Florida, Santa Rosa County, Florida.  Preliminary damage is estimated to be over 5 billion US Dollars.  <Click here> for before and after aerial damage photos.
 
   A microbaragraph, which measures atmospheric pressure <click here>,  shows pressure with time as the western eyewall approached the National Weather Service Office located on Bates Field in western Mobile, Alabama.  The observed minimum central pressure was 28.48 in. (or 964 millibars).  Brookley Field (KBFM, not shown) was located 32 miles northwest of the eye and measured 28.23 in. (or 956 millibars) of atmospheric pressure.  The minimum central pressure measured by NOAA Research Aircraft at the time of landfall was 27.85 inches(or 943 millibars).  Note the 13 millibar pressure difference that existed over a straight line distance from Brookley Field in northwest Mobile Bay  to the center of Ivan located over extreme southeastern Mobile Bay (wow!).

Animated hourly radar loop of Hurricane Ivan Hurricane Ivan Rainfall Hurricane Ivan Atmospheric Pressure Hurricane Ivan Observed Data
<click to animate> <click to enlarge> <click to enlarge> <click to enlarge>

Table 1
below gives hourly 0.5 degree radar reflectivity images taken from the National Weather Service WSR-88D Doppler Weather Radar in Mobile, Alabama (KMOB) prior to, during and after landfall.  <Click here> to view an animated hourly radar loop of Hurricane Ivan (.mpg file, faster loading).


Table 1- Hourly radar reflectivity images (0.5 deg) taken from the National Weather Service WSR-88D Doppler Weather Radar prior to, during and after landfall


9 PM CDT 10 PM CDT 11 PM CDT Midnight N Eyewall Landfall (1251 AM CDT)
1 AM CDT Eye Landfall ( 2 AM CDT) 3 AM CDT 4 AM CDT 5 AM CDT
6 AM CDT 7 AM CDT 8 AM CDT 9 AM CDT  
 
   As a major characteristic of most landfalling hurricanes, Ivan's maximum surface winds occurred within the right front quadrant of the storm (or northeast of Ivan's center given the orientation of approach in this case) just prior to and after landfall.  <Click here> to see WSR-88D radar reflectivity location of strongest surface winds at the time of landfall.   <Click here> to see WSR-88D radar velocity location of strongest surface winds surrounding  landfall ( faster loading .mpg )...or...8 min resolution .gif (large ~18 MB) or 4 min resolution .gif  (very large ~36 MB).  Note the large area of 124 knot winds at the 3000 feet level above ground northeast through east with respect to Ivan's center. 

   A loss of power and phone lines well before landfall rendered many observational platforms unable to continue logging data.  Table 2 below yields information on regional peak wind gusts during this event.  Click on the buoy and Dauphin Island, Alabama C-MAN locations in Table-2 below to view time series plots of sustained wind speeds, wind gusts and wave heights.  You may note upon observing Buoy 42040 (70 miles south of Dauphin Island, Alabama ) that significant wave heights reached a maximum of 52 feet (not to be confused with storm surge along the coast!).   Buoy 42040 later went adrift from its' mooring.  Note that most of the peak wind gust data was obtained from the relatively weaker west side of Ivan.  Although there are no surface wind observations available over inland southwestern Alabama, an estimated 80-100 mph winds near Ivan's center caused major tree and structural damage along his path over Escambia, Conecuh, Monroe and Wilcox counties of Alabama.
 
 
Table 2- Observed peak wind gusts (mph) and times (CDT) during Hurricane Ivan. Assume wind gusts were observed on 16 September unless otherwise noted.  *** - indicates Eglin Air Force Base, FL Wind Sensor- ***


Location
Peak Wind Gust Value (mph)
Time
Location
Peak Wind Gust Value (mph)
Time
Sailboat anchored in Wolf Bay
Baldwin County, AL
145 unknown      
2 SW Mary Esther, FL
(200' high over Gulf)
119
350 AM
Buoy 42040 (70 mile south of Dauphin Island, AL)
85
15th / 443 PM
Gulf Shores Airport, AL  (DOW)
115
unknown
Buoy 42007 (20 miles south of Ocean Springs, MS)
78
1242 AM
Pensacola Naval Air Station, FL (KNPA)
107
138 AM
Mobile AL 
(KMOB, Bates Field)
 75  212 AM
Pensacola, FL (10 m Gill)
106
144 AM
Mobile, AL Downtown
(WKRG Studios)
74
104 AM
Battleship Park, AL
on Mobile Bay
105
135 AM (no data thereafter)
 Fairhope, AL (AWIS)  72  15th / 1118 PM
Dauphin Island, AL C-MAN
102
15th / 1029 PM
Grand Bay, AL
71
1217 AM
Pensacola Airport, FL(KPNS)
101
150AM (no data thereafter)
8 SW Mossy Head, FL
69
1210 AM
 10 S Harold, FL ***  90  1210 AM
Spanish Fort, AL
59
3 AM
Fairhope, AL (10 m Gill)
89
144 AM
Semmes, AL (AWIS)
59
1230 AM
10 N Mary Esther, FL ***
86
1230 AM
Grand Bay, AL (RAWS)
58
1217 AM
5 NE Seminole, FL ***
86
440 AM
Semmes, AL (NWS Mesonet)
56
12 AM
Evergreen, AL (KGZH)
47
1253 AM
  
   Ivan's path of destruction did not stop in the coastal counties, however.  The winds around the center of a landfalling hurricane can remain above hurricane force (> 74 mph) well inland (and most certainly in higher gusts).  That was certainly the case with Ivan.  <Click Here>  to see the path traced out by the highest radar reflectivities (> 50 dBZ, obtained from the KMOB WSR-88D).  In these intense squalls very near the eyewall, higher winds just above the surface are efficiently transported down to the ground.  As one can see in the above figure, Ivan carved a path of wind destruction as it moved well away form the coast. The National Weather Service in Mobile, AL issued Inland Hurricane High Wind Warnings for the affected counties well in advance of Ivan's arrival into inland southwest Alabama. 

Table 3 yields event regional storm surge information obtained from various tide gauges.   Although not measured by a tide gauge and storm surveys are not yet complete as of the time of this writing, the storm surge was likely historic from Fort Morgan, Alabama east to near Navarre Beach, Florida.  The surge along this stretch of coastline was likely at least as high as 10 feet and possibly 12 feet.  Fortunately, for downtown Mobile, Alabama, the center of Ivan passed to the east preventing nearly 16 to 18 feet of devastating storm surge, which is what would have happened if Ivan would have made landfall west of Mobile Bay.



Table 3- Observed storm surge data (ft, referenced to NGVD) during Hurricane Ivan.  Courtesy of U.S. Army Corps of Engineers, Mobile District.
1 USGS gage     2 Outside High Water Mark     3 Inside High Water Mark

<Click here> for an area map depicting the following storm surge data.

 

Tide Gage Designation

Peak During
Ivan
(ft-NGVD)
Peak During
Georges
(ft-NGVD)
Peak During
Opal
(ft-NGVD)
Peak During
Frederic
(ft-NGVD)

1Mississippi Sound at Waveland, MS (USGS)

4.56

 

 

 

Gulfport Harbor at Gulfport, MS (540)

4.63

7.05

 

2.98 

Mississippi Sound at Ship Island

5.15

     

Biloxi Bay at Point Cadet

4.23

7.17

   

Back Bay Biloxi at Biloxi, MS

 

8.05

   

1West Pascagoula River at Hwy 90 at Gautier, MS

4.10

 

   

2Pascagoula River (NOAA) at Pascagoula, MS

6.72

8.36

 

5.78 

Mississippi Sound at Pascagoula PI- Rear Range

5.83

 

   

Mississippi Sound at Petit Bois Island

4.83

 

   

1Escatawpa River at I-10 nr Orange Grove, MS

3.93

 

   

Middle Gage at Bayou LaBatre

4.66

8.27

   

2Mobile Bay at Cedar Point, AL

6.90

5.60

   

3Dauphin Island Bay at Dauphin Island

7.80

5.00

4.50

7.80

2Mobile Bay at Dauphin Island (USCG)

8.00

4.59

   

Mobile River at Mobile, AL

4.87

8.94

 

8.05

Mobile River at Bucks, AL (Barry Steam Plant)

6.82

 

 

5.50

Mobile Bay at Ft Morgan Front Range

7.85

 

   

Mobile Bay at Middle Bay Light House

 

 

   

Perdido Pass Orange Beach, AL

8.81

5.58

5.40

7.10

GIWW at Pensacola Gulf Beach, FL

9.68

 

 

7.19

3Pensacola Bay at Ft. McRee, FL (USCG)

9.70

 

7.50

 

3Pensacola Bay at Pensacola, FL (NOAA)

10.20

 

6.20

 

3Escambia Bay West Bank at HWY 90

12.92

     

3Escambia Bay West Bank 1.5 miles N of I-10

12.12

     

3GIWW at Gulf Breeze, FL

10.30

 

6.30

 

1Yellow River near Milton, FL

9.66

 

   

Fort Walton Brooks Bridge

6.12

 

5.80

 

Destin at Choctawhachee Bay (USCG)

5.39

4.60

6.80

3.28

GIWW at Choctawhachee Bay (HWY 331)

5.51

 

   

GIWW at West Bay, FL (HWY 79)

6.60

 

   

St Andrew Bay at Panama City, FL

4.94

3.51

   

Watson Bayou at Panama City, FL

 

 

6.92

 

Apalachicola River at Apalachicola, FL

5.10

4.52

6.40

 

GIWW at St. George Island, FL

3.55

 

   

Carrabelle River at Carrabelle, FL

5.04

4.58

5.54

 
 
Regarding rainfall, clearly the highest rainfall amounts occurred east of Ivan's center as it moved northward into southwestern Alabama.  <Click here> to view the storm total precipitation image as measured by the Mobile, Alabama WSR-88D.  The time span of rainfall shown in this image ranges from 734 PM CDT 14 Sep to 429 PM CDT 16 Sep 2004.  The absence of shower and thunderstorm activity prior to the arrival of Ivan's significant rainbands means that this time period captured nearly all of the event rainfall associated with Ivan.  The radar-estimated data shows a large swath of greater than 5 inches of rain over coastal Alabama and the extreme western Florida Panhandle.  Fortunately, due to Ivan's relatively fast northerly motion (13-16 mph) after landfall, rainfall amounts were limited compared to some past tropical systems (eg.. Hurricane Danny 1997 which deposited nearly 43 inches of rainfall over a two-day period while over southwestern Mobile Bay).  A narrow swath of heavy rain occurred about 15 miles either side of a line from Orange Beach, AL to Barrineau Park, FL to Atmore, AL to just west of Monroeville, AL.  Along this line, radar estimated between 10 and 15 inches of rain.  Rainfall amounts were much less west of Interstate-65 in Alabama where 2 to 4 inches of rain fell.  Table 4 yields actual 24 h rain gauge amounts across the region ending 7 PM CDT, 16 Sep 2004.
  


Table 4- 48 h rainfall (in.) totals ending 7 PM CDT - 16 Sep 2004 for select locations around the region.  Note the the lesser amounts west of Ivan's track.


Location 48 h Rainfall (in.) ending
7 PM CDT -16 Sep 2004
Location 48 h Rainfall (in.) ending 
7 PM CDT - 16 Sep 2004

Pensacola, FL (WEAR Studios)

15.79

Niceville, FL

6.55

Silverhill, AL (3S)

10.16

Mobile, AL (7S KMOB)

6.53

Andalusia, AL (HAM)

9.96

Munson, FL

6.50

Mobile, AL (2S KMOB)

9.90

Mobile, AL (3S KMOB)

6.30

Mossy Head, FL (10S)

8.92

Coden, AL (NWS COOP)

6.30

Crestview, FL (HAM)

8.40

Ft. Walton, FL (HAM)

6.06

Seminole, FL (5 NE)

8.10

Harold, FL (10S)

5.72

Mobile, AL (10S KMOB)

8.00

Mobile, AL (Bates Field, KMOB)

5.56

Pensacola Naval Air Station (NPA)

8.00

Semmes, AL

5.00

Daphne, AL

7.50

Richton, MS (NWS COOP)

4.50

Valparaiso, FL (Eglin AFB, KVPS)

7.43

Thomasville, AL (NWS COOP)

4.20

Evergreen, AL (NWS COOP)

7.25

Dothan, AL (KDHN)

3.21

Alberta, AL

6.85

Troy, AL (KTOI)

2.90




Acknowledgements:  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.  MVERIFY buoy and C-MAN time series provided by David Eversole (Lead Forecaster, NWS Mobile, AL).


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