Why was the storm surge in Biloxi, Mississippi so much higher than expected?

[Ivan Seeking]

With the understanding that I'm taking no credit for this, rather, I was simply regurgitating what had been seen on TV - science shows on DSC, NGC, etc - I predicted a 50ft storm surge around Biloxi Miss. AFAIK this was not predicted by the experts but I can hardly understand why. And it's starting to look like I was pretty close in the areas worst hit near Biloxi. I took one look at the rotation with the strong side extending far around the peninsula and into the gulf, and taking into account the funneling effect of the gulf, it was easy to see that it was just as has been described in many of the TV shows seen about the Tsunami; we should see the surge amplified significantly by the parabola. So I made a seat of the pants guess that we would see a surge 500% greater than expected, and, looking at the coastline, Biloxi seemed to be close to the focal point. I can't understand how I could know this was likely simply by watching TV, and yet no one was officially expecting such a high surge.

I brought this up because of some of the latest reports from areas that are completely decimated seem to indicate that a 30 foot + surge did hit. This also makes me think of the freak wave phenomenon... It would seem that there is ample opportunity to study the models here. That, or people knew this was coming but the information simply didn't get out.

Incidently, and I swear this is the absolute truth, I had no sooner made this prediction to Tsu that CNN reported that a weather bouy had just measured a 46 foot swell.

In either case, another plug for Oregon State University since it has one of the premier wave tanks for such studies.

 

[Astronuc]

Well, I believe the estimates were something like 25-30 ft (7-9 m) in the surge (rise above normal sea level). On top of that, add 10-25 ft (3-7 m) waves, and the result is 35-55 ft (11 - 17 m) swells.

Also one has to factor in underwater terrain which affect wave heights.

This is pretty much what has been expected for a long time, and we will likely see more of this.

Map of hurricanes in US - 1950-2004 - http://lwf.ncdc.noaa.gov/img/climate/severeweather/hur5005.jpg

from

http://lwf.ncdc.noaa.gov/oa/climate/severeweather/hurricanes.html

History of many US hurricanes
http://www.nhc.noaa.gov/HAW2/english/history.shtml

 

[hypatia]

I believe it was also high tide. I had read 28 to 30 pre-storm, but haven't heard about actual figures..anyone have a link? I know the loss of wet lands in the past 2 decades really made a difference, anyone know how far inland the water went?

 

[Astronuc]

I believe it was also high tide. I had read 28 to 30 pre-storm, but haven't heard about actual figures..anyone have a link? I know the loss of wet lands in the past 2 decades really made a difference, anyone know how far inland the water went?

Monday, Aug 29 - High Tide 5:02 AM and hurricane eye was right on the coast at the SE point of LA.

I am not sure about how far the water got, but it was probably a few miles, and more so because of the bay and rivers.

Another problem for New Orleans is that Lake Ponchatrain is about 14 feet above sea-level and New Orleans is at or below sea-level.

What has been needed is a by-pass around New Orleans, but that is not very effective when there is a storm surge pushing the sea-level higher. Then there is no place to pump the water, and the levees are the only protection, and that assumes the pumps are working.

 

[Ivan Seeking]

When I made this prediction, the news channels were reporting an expected eight foot surge. So if the experts knew to expect this, the word didn't get out to the news agencies. Note that I simply added a little to the reports at the time and then multiplied by five.

 

[Bystander]

"Eight" vs. twenty-something? Sounds almost like a metric-English conversion omitted between computer and news release.

 

[Astronuc]

When I made this prediction, the news channels were reporting an expected eight foot surge. So if the experts knew to expect this, the word didn't get out to the news agencies. Note that I simply added a little to the reports at the time and then multiplied by five.

Well something is very wrong with the media.

I was following Katrina and I read this from the National Hurricane Center - which was consistent with earlier warnings.

HURRICANE KATRINA ADVISORY NUMBER 26
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
4 AM CDT MON AUG 29 2005

COASTAL STORM SURGE FLOODING OF 18 TO 22 FEET ABOVE NORMAL TIDE
LEVELS...LOCALLY AS HIGH AS 28 FEET...ALONG WITH LARGE AND DANGEROUS
BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE
CENTER MAKES LANDFALL. SOME LEVEES IN THE GREATER NEW ORLEANS AREA
COULD BE OVERTOPPED. SIGNIFICANT STORM SURGE FLOODING WILL OCCUR
ELSEWHERE ALONG THE CENTRAL AND NORTHEASTERN GULF OF MEXICO COAST.
NOAA BUOY 42040 LOCATED ABOUT 50 MILES EAST OF THE MOUTH OF THE
MISSISSIPPI RIVER RECENTLY REPORTED WAVES HEIGHTS OF AT LEAST 46
FEET.

 

[Ivan Seeking]

NOAA BUOY 42040 LOCATED ABOUT 50 MILES EAST OF THE MOUTH OF THE MISSISSIPPI RIVER RECENTLY REPORTED WAVES HEIGHTS OF AT LEAST 46 FEET.

Incidently, and I swear this is the absolute truth, I had no sooner made this prediction to Tsu that CNN reported that a weather bouy had just measured a 46 foot swell.

This clearly came out just after my own guess. I would hope that the NWS could out guess Ivan and the DSC.

 

[Astronuc]

This clearly came out just after my own guess. I would hope that the NWS could out guess Ivan and the DSC.

Yeah, right! You better come clean Ivan. What were you doing down there that got out of control.

Seriously, here is the rest of the story - here are some excerpts of public advisories with date and time:

NHC Archives of Katrina - http://www.nhc.noaa.gov/archive/2005/KATRINA.shtml?
The public advisories are in the second column.

http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.025.shtml?

HURRICANE KATRINA ADVISORY NUMBER 25
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 PM CDT SUN AUG 28 2005

COASTAL STORM SURGE FLOODING OF 18 TO 22 FEET ABOVE NORMAL TIDE
LEVELS...LOCALLY AS HIGH AS 28 FEET...ALONG WITH LARGE AND DANGEROUS
BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE
CENTER MAKES LANDFALL. SOME LEVEES IN THE GREATER NEW ORLEANS AREA
COULD BE OVERTOPPED. SIGNIFICANT STORM SURGE FLOODING WILL OCCUR
ELSEWHERE ALONG THE CENTRAL AND NORTHEASTERN GULF OF MEXICO COAST.


http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.019.shtml?

HURRICANE KATRINA ADVISORY NUMBER 19
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
10 PM CDT SAT AUG 27 2005

MAXIMUM SUSTAINED WINDS REMAIN NEAR 115 MPH WITH HIGHER GUSTS.
KATRINA IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON SCALE.
STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS...AND KATRINA
COULD BECOME A CATEGORY FOUR HURRICANE ON SUNDAY.

COASTAL STORM SURGE FLOODING OF 15 TO 20 FEET ABOVE NORMAL TIDE
LEVELS...LOCALLY AS HIGH AS 25 FEET ALONG WITH LARGE AND DANGEROUS
BATTERING WAVES...CAN BE EXPECTED NEAR AND TO THE EAST OF WHERE THE
CENTER MAKES LANDFALL.

HEAVY RAINS FROM KATRINA SHOULD BEGIN TO AFFECT THE CENTRAL GULF
COAST SUNDAY EVENING. RAINFALL TOTALS OF 5 TO 10 INCHES...WITH
ISOLATED MAXIMUM AMOUNTS OF 15 INCHES...ARE POSSIBLE ALONG THE PATH
OF KATRINA.

http://www.nhc.noaa.gov/archive/2005/pub/al122005.public_a.018.shtml?

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
7 PM CDT SAT AUG 27 2005

MAXIMUM SUSTAINED WINDS ARE NEAR 115 MPH...WITH HIGHER GUSTS.
KATRINA IS A CATEGORY THREE HURRICANE ON THE SAFFIR-SIMPSON
SCALE. STRENGTHENING IS FORECAST DURING THE NEXT 24 HOURS...AND
KATRINA COULD BECOME A CATEGORY FOUR HURRICANE LATER TONIGHT OR
SUNDAY.

HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 45 MILES FROM THE
CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 160
MILES. NOAA BUOY 42003 LOCATED NORTHWEST OF THE CENTER RECENTLY
REPORTED SUSTAINED WINDS OF 54 MPH WITH A GUST TO 64 MPH AND
25-FOOT WAVES.

So Saturday night between 7 pm and 10 pm, the advisory changed -


Back on Friday - when it was a Cat 2 storm.

http://www.nhc.noaa.gov/archive/2005/pub/al122005.public.015.shtml?

MAXIMUM SUSTAINED WINDS HAVE INCREASED TO NEAR 105 MPH WITH HIGHER
GUSTS. KATRINA IS A CATEGORY TWO HURRICANE ON THE SAFFIR-SIMPSON
SCALE. KATRINA IS EXPECTED TO BECOME A MAJOR HURRICANE DURING THE
NEXT DAY OR TWO.

STORM SURGE FLOODING OF 2 TO 4 FEET ABOVE NORMAL TIDE LEVELS...
CAN BE EXPECTED ALONG THE SOUTHWEST COAST OF FLORIDA IN AREAS OF
ONSHORE FLOW EAST OF CAPE SABLE... AND IN FLORIDA BAY. STORM SURGE
WILL GRADUALLY SUBSIDE TONIGHT AND SATURDAY.

By Saturday night, the NHC predicted a major Cat 4 storm. However, it was a Cat 2 earlier in the day.

Things can change rapidly, as is well known - or should be well known by those who chose to live along the Atlantic and Gulf Coasts.

This is all publicly available information.

 

[Ivan Seeking]

CNN reported today that the storm surge at Gulfport Beach, Mississippi, at the aquarium, reached 41 feet.