1992 Andrew report update

[Pearl River]

Derek, the wind gust was from Camille. I'm not sure the anemometer type. I would assume that it was the most widely used type of anemometer back in 69.

Another thing we have to figure as far as surge goes, Camille came in at an angle from the southeast, where as Katrina came from the due south.

[Derek Ortt]

did Camielle hit the coast that is due west/east, or did it hit the small part that is WSW/ENE? I am not sure, myself, if it caught the angleed part or if it just missed

[Margie]

Another thing we have to figure as far as surge goes, Camille came in at an angle from the southeast, where as Katrina came from the due south.

Not really so much of a difference. Camille moved almost due north in the 12 hours before landfall, true N in the last four hours before landfall, then turned NW briefly right at landfall.

From 1pm on Sunday, until just before landfall at 11pm, Camille moved 2.2 deg lat N and only 0.5 deg long W, so she was coming from the SSE, roughly between 165-170deg. In the last 4 hours before landfall she moved due north, from 29.5 lat to 30.3 lat.

Also HF winds at landfall had almost certainly spread out further (to the east) than the 60nmi found early Sun aft by the last recon, when the storm was 250mi offshore.

[Margie]

did Camielle hit the coast that is due west/east, or did it hit the small part that is WSW/ENE? I am not sure, myself, if it caught the angleed part or if it just missed

The eye (12nmi diam), which had been forecasted to come in right at the state line, as Kat did, went almost directly over Waveland.

Prior to landfall, storm had been moving just a hair W of due N, and moved NNW for a short time after landfall (see prev post). Basically...it hit Waveland, the Pass, and Long Beach almost exactly perpendicular to the coastline...even a little more so than Kat.

[Javlin]

I would have to disagree that KATRINA brought in with her a Cat 3 surge.I myself have seen the effects of storms along the coast from Camille onward.This was no 3!I do believe that the wind speed goes will with a Cat 3 though.I think that once Katrina made a Cat 5 status briefly the energy was transmitted to the ocean waves.Had Katrina reached the Cat 5 status sooner and back to the 3 + 4 quickly maybe the surge would have gone down some.Energy can neither be created nor destroyed right.The flooding up in the bayous and bays was unpresented in our lifetime and as far as what we know from the recorded history of the Gulf Coast.There has been others in the pass along 2+3 status that do not even come vaguely close.

Another note I was over in Goula the other day picking up a vehicle the salesman told us 5' of water in the building and this was 1 mile off the beach and 60 miles or so from the eye.That's alot of energy.

[Margie]

I would have to disagree that KATRINA brought in with her a Cat 3 surge.

Another note I was over in Goula the other day picking up a vehicle the salesman told us 5' of water in the building and this was 1 mile off the beach and 60 miles or so from the eye.That's alot of energy.

Generally, yes it was only Cat 3. The area that did receive higher surge, Cat 4 level, was statistically very very small (details of where, are in another post I have under the post tropical cyclone reports).

Yes the Cat 3 surge did extend as far east as Pascagoula. Cat 3 surge finally ran out just NE of Pascagoula city limits. It was the large size of Katrina that extended the Cat 3 surge so far. Yes it was a lot of energy.

The salesman was probably off by a little, or his store could have been at slightly lower ground.

My brother's house on Buena Vista Street just south of Ingalls Ave, received 3-4 feet of water. That area is 10 feet above sea level and his house is built 13 feet above sea level from the street elevation (typical of many homes where the ground slopes up a bit from the street). They did receive about 17 ft surge there.

Over 90% of Pascagoula city limits was flooded, possibly over 95%. Not only that, the majority of the city did get between 3-4 ft of water over the ground elevation. In fact, hard to believe, but a larger portion of homes in Pascagoula were likely flooded to a higher extent than in Bay St Louis (which sits on higher ground)...something I'm currently trying to get more data on.

This does not mean the surge, for the most part, was higher than a Cat 3. What will be helpful in understanding this is to review the Hurricane Evacuation Study maps which show how far inland each surge level can go. Jackson Co is in an even more vulnerable position than Hancock. Most of Jackson Co is part of the Pascagoula River basin, including a very large estuary. In areas where the elevation remains low very far inland, the surge can penetrate many miles inland. Storm surge (salt water) likely went quite far upriver in that county.

The areas where the surge went above Cat 3 levels were very narrow strips of land right on the coastline surrounding St Louis Bay. We're talking not further inland than say 1/2 mile, but much more likely just 1/4 mile inland. The surge did reach Cat 4 levels on those small portions of land and was just short of Cat 5 levels. If the high tide is subtracted from the storm tide, which still has to be done, this will drop the actual surge levels at most 2 feet. This will likely still result in Cat 4 surge for a tiny area. Those portions of land start at sea level right on the shoreline and increase in elevation to about 20 feet by the time you are 1/4 mile in (roughly). Let me put it this way: if you have 20 ft of surge, plus 2 ft high tide, plus 20 ft waves at the shoreline, reducing in height as you go in, probably not more than 3-5 ft high once you get past 1/4 mile inland...it is not going to matter much if the surge increases to 23 ft.

Now it happened that the very highest surge impacted an area where the ground rises quickly to above 20 feet: just along the shoreline of eastern Hancock County, and eastern Pass Christian / western Long Beach area (because of the geography, western Pass Christian and Henderson Point received slightly less surge...but only slightly). Consider this: if that level of surge had hit a lower-lying area such as eastern Jackson County, the level of flooding would have been so deep as to be almost incomprehensible. Also remember that areas like Henderson Point were leveled mainly by large shoreline waves along with the surge.

[Aslkahuna]

The AirForce did not have an operational hot wire anemometer in 1969-they generally used the Aerovane system with chart recorders which I suspect the NWS also used at the time. The Aerovanes were more robust than current ones and could operate on the recorder without power since the recorders were clock wound. The only problem is that the control tower control which windsensors were on line and often took them all offline when they evacuated (I had to send a tower operator back up duirng Typhoon Irma in 1974 so that we could get the wind readings back online thus we obtained a full record of Irma's winds). Note that during Andrew, the wind sensor at NHC held up to 164 mph gusts until the Radome blew off and took out the sensor.

Steve

[MGC]

Margie, have you been down here to the coast to look at the surge damage? If not then you need to before you make comments concerning the surge. So in your opinion what would a Cat-5 surge be on the coast, 50 feet? Katrina's surge was the greatest since the French settled the Mississippi coast and I'm sure we've had our share of big hurricanes since 1699......MGC

[docjoe]

[quote="Derek Ortt"]60 miles would make Camielle roughly the size of Ivan then.

according to the 2AM CDT advisory on Sept 16 hurricane winds for Ivan extended outward up to 105 miles...making it quite a bit larger than Camille in my mind. Was this later adjusted downward in the final analysis. BTW...great thread for laymen like myself.

docjoe

[Derek Ortt]

the surface obs at landfall did not indicate winds any more than 60NM from the center. It is even questionable if they were 60NM as Ft Walton did not have sustained hurricane force winds

[docjoe]

Margie, have you been down here to the coast to look at the surge damage? If not then you need to before you make comments concerning the surge. So in your opinion what would a Cat-5 surge be on the coast, 50 feet? Katrina's surge was the greatest since the French settled the Mississippi coast and I'm sure we've had our share of big hurricanes since 1699......MGC

Why do you have to see it to comment on it. Please correct me if I am wrong but storm surge values are not static numbers. For one coastline Cat 3 surge may be 12-15 feet while on another one 18-22 feet may be representative of a Cat 3 surge. So if the measured surge in MS fell within established Cat 3 levels for that section of coastline then that is how it should be classified ....whether one sees it or not.

docjoe

[docjoe]

the surface obs at landfall did not indicate winds any more than 60NM from the center. It is even questionable if they were 60NM as Ft Walton did not have sustained hurricane force winds

interesting...thanks alot!!

docjoe

[Javlin]

Margie, have you been down here to the coast to look at the surge damage? If not then you need to before you make comments concerning the surge. So in your opinion what would a Cat-5 surge be on the coast, 50 feet? Katrina's surge was the greatest since the French settled the Mississippi coast and I'm sure we've had our share of big hurricanes since 1699......MGC

Why do you have to see it to comment on it. Please correct me if I am wrong but storm surge values are not static numbers. For one coastline Cat 3 surge may be 12-15 feet while on another one 18-22 feet may be representative of a Cat 3 surge. So if the measured surge in MS fell within established Cat 3 levels for that section of coastline then that is how it should be classified ....whether one sees it or not.

docjoe

Sure they vary from from one point to another but I do believe the surge was even more than the NHC expected.Even by there own remarks Katrina was a once in alifetime at best and was a freak system.Surge going in 5-6 miles is not normal with any system we have seen in these parts ever.This being said would not if it was considered a NORM then the new elevations for construction reflect this,they don't.They are on the order of what we usually observe it's varing at the moment form 4'-8' depending on municapality.
Saffir scale list surge normally for a Cat 5 will exceed 18' (30'+ in some areas)and flooding between 5-10 miles inland.A Cat 4 results in damage to lower floors near the shore with major damage per the NHC.I think total destruction nothing left hardly of 90% of the structers all along the coast does not even fit the Cat 4 rating by the NHC.Houses that have existed for up to 175 yrs old are gone people nothing is left on the beach it looks like Hiroshima if you need a picture.I just went back and read the 6:00 am advisory 18'to 22' surge expected as much as 28' locally these all happened and exceeded in some cases these are in line for a Cat 5 surge per the NHC.

[Margie]

Margie, have you been down here to the coast to look at the surge damage?

I think I've explained this before in a different thread...if you go to this tool you will be able to see -- very clearly -- the land that would be inundated by the various levels of surge. It is essential that you understand the nature of surge in a tidal basin if you want to comment effectively on this topic.

http://ekman.csc.noaa.gov/website/FEMA_ ... ississippi

Turn off evac zones and select surge once you have the map up.

The area of BSL that would have only been inundated by Cat 5 surge, was high and dry. Ditto the high ground along eastern Pass Christian into Long Beach.

Only a very limited area of land experienced Cat 4 surge, as I described previously...some small areas right along the coastline.

There is actually very little high ground along the MS Gulf Coast. The areas that could have been flooded by a Cat 4 or Cat 5 surge are extremely small, as can be seen by the evac zones tool.

[Margie]

the surface obs at landfall did not indicate winds any more than 60NM from the center. It is even questionable if they were 60NM as Ft Walton did not have sustained hurricane force winds

Hmmm...I think Pascagoula proper, which is right on the shore, had 3-4 hours of high winds; I would be surprised if they did not get any of hurricane force.

[Derek Ortt]

that was Ivan I mentioned about the winds.

Pascagoula had upper cat 1 or perhaps lower cat 2 from Katrina

[MGC]

All of Bay St. Louis city was flooded. Water covered Hwy 90. There was water from the sound to the bay. Wal Mart in Waveland had several feet of water in it. So, it is not a Cat-5 surge if water covers the entire town?. I have a coworker who owns a house in the Bay, his house is located in a Cat-4 surge area and the water was up to the roof. I think their surge maps are a little off....MGC

[Margie]

How can I make this any clearer? How about this: Most of BSL would flood in a Cat 2.

Let me say it again: Most of BSL would flood in a Cat 2.

And, one more time: Most of BSL would flood in a Cat 2.

You are correct the WalMart and Hwy 90 flooded (from the bay side actually), however the area around the water resevoir, Cat 5 elevation, did not flood.

To answer your question "is it not a Cat 5 surge if water covers the entire town?" NO. It is a Cat 5 surge if water covers the area that will flood in a Cat 5 storm, or, if water came to a Cat 5 height in an area of lower elevation (i.e. the shoreline). To determine the level of flooding you need to look at the map of the hurricane surge zones for that storm basin, which was generated by SLOSH model runs, and compare it to the area that did flood.

So, please, look at the surge maps before you make any more comments regarding a Cat 5 level surge.

[Pearl River]

Old town Bay St Louis lost it's buidings on the coast. It was located in the cat 4 area.

[Margie]

Old town Bay St Louis lost it's buidings on the coast. It was located in the cat 4 area.

"...on the coast" is the key.

Destroyed by surge...or by large waves on top of the surge? It was the waves.

Debris line from the waves in the Waveland and immediate S and E coastal area of BSL went in about a half mile. That is also true for Clermont Harbor and Lakeshore.