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Archives 2000s >> 2006 News Talkbacks

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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Hi all [Re: danielw]
      #64780 - Mon Mar 27 2006 10:03 AM

Quote:

I thought that I had a good grasp on the High Water Marks. But now I'm slightly confused.
The 25.72ft that FrankP mentioned minus the 14ft elevation above sea level at his front yard. Gives me a water depth (surge?) of 11.72ft. Which seems consistant with the damage to his house.
Please PM me if I'm missing the math.



No that water mark was a good one. It was the 35 ft one in the Pass that was wrong.

You have the elevation right...14 ft in the front yard, 16 ft at the slab, the 18 foot mark starts a little further back on Frank's property. But the reason the house is gone is mainly due to wave runup and current. It is easy for water to get inside; once water is inside and outside the pressure equalizes and the house will remain standing (like 80% of the homes in Pascagoula which are destroyed inside by being subjected to five feet of salt water, but look almost perfectly normal from the outside). What happens in the velocity zone is that repeated pounding will remove the structure of the home from its footings, and eventually the first floor shifts and quickly collapses. The second floor can sometimes stay mostly together as Frank's did, riding along on top of the water and debris, coming to rest when the water level subsides (as his did, further back from the beachfront). More usually it is just the roof that will stay together.

One thing Stephen Baig mentioned to me was that depending on which elevation reference you use, and how old it is, it might be a little high, because of continuing subsidence along the entire Gulf Coast. FEMA used NAVD 88 as the reference, but they also used LIDAR data from 2004 to do the surge inundation maps. This could be like comparing apples and oranges, but I am not sure. It would be good to find an expert in this area to provide some feedback (anybody know any surveyors?).

Here is more detail on the way the mapping was done:

http://www.fema.gov/hazards/floods/recoverydata/pdf/katrina_ms_methods.pdf

And here is an FAQ from the NGS:

http://www.ngs.noaa.gov/faq.shtml#WhatVD29VD88


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ltpat228
Storm Tracker


Reged: Tue
Posts: 201
Loc: Port Saint Lucie FL
Re: Another South Atlantic TC?? [Re: Lee-Delray]
      #64781 - Mon Mar 27 2006 02:37 PM

Thank you, Lee, for turning me on to the article in the PB Post.
Obviously as you and I live 1 hour apart and have suffered much devastation these last 2 hurricane seasons, local comments like your link displayed are always comforting and informative.
I'm only 50 miles up the road from ya if FEMA gets the ice to my area first this year...ha ha!


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Lee-Delray
Weather Master


Reged: Thu
Posts: 429
Re: Another South Atlantic TC?? [Re: ltpat228]
      #64782 - Mon Mar 27 2006 06:28 PM

This time in 2004 we would have laughed at that article and wondered who FEMA was.

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Lee-Delray
Weather Master


Reged: Thu
Posts: 429
Re: Another South Atlantic TC?? [Re: Lee-Delray]
      #64783 - Tue Mar 28 2006 09:26 AM

Here's another that was on yahoo today about the Northeast.

http://news.yahoo.com/s/ap/20060328/ap_on_sc/northeast_hurricane


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ZooKeeper
Verified CFHC User


Reged: Tue
Posts: 24
Loc: Live in Chiefland & work in Ce...
Re: Another South Atlantic TC?? [Re: Lee-Delray]
      #64784 - Tue Mar 28 2006 12:49 PM

Hello Glenda! Looks like the Aussies are expecting Round Two. I've got some friends down under that are currently preparing for this one.
http://www.wunderground.com/blog/JeffMasters/show.html

--------------------
The storm that began a lifelong facination: Donna 1960 (Eyewall)


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Ouch [Re: ZooKeeper]
      #64787 - Thu Mar 30 2006 09:11 AM Attachment (294 downloads)

Look at this microwave image of Glenda just before landfall (attached). Ooooee.

Good surge pic:

http://www.theaustralian.news.com.au/

I liked this site -- be sure to read the article "Bureau's Wind Speed Hot Air."
http://www.theaustralian.news.com.au/common/story_page/0,5744,18661726%255E2702,00.html

And here is a sat image from Japan:

http://images.wn.com/i/f2/76372a7acfae4b.jpg

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp

Edited by danielw (Sat Apr 01 2006 09:48 AM)


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
that HWM in the Pass [Re: Margie]
      #64791 - Thu Mar 30 2006 02:38 PM

Ok here is the deal. I contacted NCDDC (btw Frank they are at Stennis, too...any questions just track down Russ Beard), and they responded promptly, and that 35 ft mark is a wave mark, practically on top of a 25 ft surge mark, probably hiding the surge mark on the map (these were likely a pair of indoor/outdoor marks). Both were thrown out by FEMA. NCDDC is in the process of adding another layer to the impact tool to hide all those marks that were thrown out; that layer was not available in the original data they received from FEMA.

Ten feet of wave runup at that location is not beyond the range of reasonable possibility, but it is towards the tail end of the distribution. If you recall videos from Gulfport and Biloxi both showed no significantly high wave runup, which is not surprising given the shallow water in the sound. I will post again if I can ever get hold of the FEMA contractor notes showing why they threw out the numbers (there will be some reason as to why they were considered not valid).

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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Lee-Delray
Weather Master


Reged: Thu
Posts: 429
Re: Another South Atlantic TC?? [Re: typhoon_tip]
      #64792 - Thu Mar 30 2006 05:27 PM

The Sun-Sentinel has another article.

www.sun-sentinel.com

My 35KW generator came today (whew).

(For some reason the above link isn't working. Click the link, and then copy and paste the whole URL into your browser. Then hit enter. That will give you the Hurricane Season story~danielw)]/i]

Edited by Lee-Delray (Thu Mar 30 2006 08:39 PM)


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danielwAdministrator
Moderator


Reged: Wed
Posts: 3515
Loc: Hattiesburg,MS (31.3N 89.3W)
Re: that HWM in the Pass [Re: Margie]
      #64793 - Thu Mar 30 2006 07:55 PM

Quote:

...and that 35 ft mark is a wave mark, practically on top of a 25 ft surge mark, probably hiding the surge mark on the map (these were likely a pair of indoor/outdoor marks). Both were thrown out by FEMA. NCDDC is in the process of adding another layer to the impact tool to hide all those marks that were thrown out; that layer was not available in the original data they received from FEMA.

...I will post again if I can ever get hold of the FEMA contractor notes showing why they threw out the numbers (there will be some reason as to why they were considered not valid).




FEMA might have thrown that 35ft mark out due to the fact it would seriously change the New Flood Maps. And the height of the new freeboard for homes and businesses. 35 foot above sea level wouldn't allow many, if any, buildings south of the Railroad tracks-Coastwide.


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LadyStorm
Weather Guru


Reged: Thu
Posts: 150
Loc: Palm Coast, Florida
Re: that HWM in the Pass [Re: danielw]
      #64794 - Fri Mar 31 2006 05:30 AM

FEMA might have thrown that 35ft mark out due to the fact it would seriously change the New Flood Maps. And the height of the new freeboard for homes and businesses. 35 foot above sea level wouldn't allow many, if any, buildings south of the Railroad tracks-Coastwide.

Just curious, Ormond Beach (my current home) is 33ft above sea level. I guess we are in deep dew dew.

--------------------
"The significant problems we face cannot be solved at the same level of
thinking we were at when we created them"

..........Albert Einstein


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HanKFranK
User


Reged: Mon
Posts: 1841
Loc: Graniteville, SC
Re: that HWM in the Pass [Re: LadyStorm]
      #64795 - Fri Mar 31 2006 08:42 AM

i think margie is right... a 35' HWM wouldn't be consistent with what the rest of the data says about surge heights in the area, or with what I generally saw. 25' looks/sounds about right, with wave action in areas.
there was an interesting phenomenon that i was guessing had to do with wave action as well, as many of the pine trees i saw near waveland had their cones missing below a certain height... what i'd roughly guess was between 30-40'. as i don't suspect the mean surge height was quite that high, mentally chalked it up as a proxy for wave action. it was a very disturbing thing to see, regardless.
might need a new thread soon. the dr. klotzbach (formerly dr. gray) forecast from csu will be out next week, i believe. yep, april 4.
HF 1342z31march


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: that HWM in the Pass [Re: HanKFranK]
      #64796 - Fri Mar 31 2006 10:20 AM

I went back and read the FEMA methodology again, and the on/off flag is an indicator of whether the HWM was used in determining surge inundation or not. Wave HWM are never used in determining inundation. The reason the surge HWM was dropped out is unknown, but it is in the same range as other nearby HWM, so that didn't change anything one way or the other.

Here is part of an email I received from FEMA's contractor last year based on questions I had about the specifics of determining the surge inundation:

"The Katrina surge inundation limits were mapped solely based on high water marks (HWMs) surveyed after the storm and Light Detection and Ranging (LIDAR) topographic data collected by the National Oceanic and Atmospheric Administration (NOAA) in 2004. More than 400 HWMs were collected in the 3 Gulf counties of Mississippi, an unprecendented number of post-storm points for an unprecedented storm. The 400+ HWMs consist of points reflecting surge-only flooding and points that include local wave effects (wave heights and wave runup). Tide was not factored out of any HWM elevation. To map Katrina's surge inundation, we used the surge-only points and mapped/labeled all of these points on the Katrina Recovery Maps."

"...The detailed appearance of the inundation limit that you perceive is more a function of the high resolution of the LIDAR data than the HWMs. In other words, we're very certain of our ground elevations to a high degree of precision, but there is inherent variability and uncertainty in the HWMs, hence our reference to the inundation limits as "approximate." That's not to say the HWMs are not accurate -- each point surveyed was required to be +/- 0.25 foot."

Actually the ABFEs that temporarily replace the existing FIRMs, before the new FIRMs are in place, are a lot lower than would be required to prevent flooding from Katrina. But they are a lot better than the ones FEMA had been working on for the last couple years, which had to be thrown out completely, because they were as much of a sham as the existing FIRMs from the 80s (which were all to the advantage of the insurance companies, which subsequently would not have to pay out very much when the 'big one' came).

Still, these new ABFEs are having trouble being accepted by many coastal communities. A lot of places simply don't want to have to build up at all, because it will change the look of the community.

HF -- yes, 15 foot waves on top of 25 feet of surge is possible for the Waveland area. But pine trees bend, and possibly they were bent under by the force of the current, rather than hit by waves. Hopefully over the next couple months I'll be able to obtain more specifics on that.

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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Randrew
Weather Guru


Reged: Tue
Posts: 109
Loc: Stuart, Florida
Re: Pine trees in Pass [Re: Margie]
      #64797 - Fri Mar 31 2006 05:40 PM

I haven't visited there since before Katrina. I am curious as to what pines you speak of. Depends what variety will bend and what will uproot in this situation.
I'm thinking most of the pines there are southern slash pines. If that would be the case then they would mostly be uprooted except for the males. They would be brutes and withstand almost anything.
Mostly the old oaks are the important indicator here. If they survived Camille then this would not be a problem for them.
If you want a true HWM then check out the oaks that are still standing.
My two cents as an old Florida farmer.


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Pine trees in Pass [Re: Randrew]
      #64798 - Fri Mar 31 2006 07:37 PM Attachment (289 downloads)

I looked at all the oaks along the coast. Quite a few of them were not sprouting any leaves at all this spring. A number of those still looked green because of all the mistletoe in them. Some had both mistletoe and a little bit of sprouting.

There are so many with extreme damage (file attached).

The saddest were the pecan orchards though; so many trees with no leaves at all and I don't know if they will recover next year.

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp

Edited by Margie (Fri Mar 31 2006 07:48 PM)


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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: Pine trees in Pass [Re: Randrew]
      #64799 - Fri Mar 31 2006 07:41 PM Attachment (254 downloads)

Here are some oaks that are done real bad from the surge (file attached). Both of these photos from Waveland.

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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Frank P
Veteran Storm Chaser


Reged: Mon
Posts: 1299
Re: Pine trees in Pass [Re: Randrew]
      #64800 - Fri Mar 31 2006 07:47 PM

for the record... the Oaks are doing great... most of the ones in my neighborhood, and we have a plethora, if they we not totally blown down, are doing fine, and all of them had at least 8 feet of salt water at their base, if not more... I have a pecan tree that also is starting to show signs of life, although its leaning about 10 -15 degrees or so, its the only one on the block so all the squirrels should be happy... not sure about my large magnolia... nothing happening with it yet so I'm a littled concerned...

My worse case scenario was that my two majestic Oaks would crash down on my house destroying it during a major storm... Never in my wildest dreams think I'd see a 26 foot surge in my yard... and I had every bit of 26 feet in the neighborhood... FEMA/NOAA said 25.72 inches... duh what's 4 inches or so... my house was 18.5 feet above sea level... my yard/lot where my house stood was 17 feet above sea level..
my next house will be 27 feet above sea level... if I lose that one I'm moving inland 27 miles... Camille & Katrina... that's two strikes for me... I've got one left...


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Frank P
Veteran Storm Chaser


Reged: Mon
Posts: 1299
Re: Pine trees in Pass [Re: Margie]
      #64801 - Fri Mar 31 2006 07:51 PM

these trees will do just fine Margie.. as long as they're sprouting growth most if not all will survive... I do have a wet oak that is not showing any signs of life at all.. and I hope it is dead because I want to cut it down anyways.. but the great live oaks look like they're going to do OK... heck they have been doing this for hundreds of years... what's another storm

Edited by Frank P (Fri Mar 31 2006 10:48 PM)


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Justin in Miami
Storm Tracker


Reged: Thu
Posts: 269
Loc: Ft. Lauderdale, Florida
GIS Data [Re: Margie]
      #64802 - Fri Mar 31 2006 08:46 PM

Margie, is FEMA posting their GIS data somewhere? I would like to see what they have. FrankP, good to see that you're hanging in up there. Funny thing about those FEMA trailers, some family in my neighborhood who unforntunately lost their roof had a FEMA trailer in their front yard. Well, so far they have decorated it with Christmas lights during the last holiday...had about 3 "outdoor" parties, and barbeque all the time.

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Margie
Senior Storm Chaser


Reged: Fri
Posts: 1191
Loc: Twin Cities
Re: GIS Data [Re: Justin in Miami]
      #64803 - Fri Mar 31 2006 09:49 PM

Quote:

Margie, is FEMA posting their GIS data somewhere?




Yes, everything is on their web site.

http://www.fema.gov/hazards/floods/recoverydata/katrina_ms_gis.shtm

--------------------
Katrina's Surge: http://www.wunderground.com/hurricane/Katrinas_surge_contents.asp


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ltpat228
Storm Tracker


Reged: Tue
Posts: 201
Loc: Port Saint Lucie FL
Re: GIS Data [Re: Margie]
      #64804 - Sat Apr 01 2006 01:05 AM

http://news.yahoo.com/s/ap_travel/200603...DlpBHNlYwMyNjgz

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