Help Needed In Assessment of Wind Speed With the EF Scale
January 7th, 2009I would like an independent analysis of what range of wind speeds would result in the damage in each picture, and an explanation (I have already attempted an analysis but do not want to bias anyone). I will greatly appreciate help, and acknowledge whoever helps me in the paper I am writing.
http://i44.photobucket.com/albums/f34/abunter/GalCo2-1.jpg
http://i44.photobucket.com/albums/f34/abunter/GalCo5.jpg
(Images courtesy of the NWS)
There appears to be more of the roof that is not in this picture. If you look closely the amount of material that would make up the roof is far less than the debris we can see in the photo. I would guess other portions of the roof are outside of the frame of the picture.
The house in the second picture is single story, so it might not be as close to the flood-prone areas.
Kiel, that gas tank looks to be a propane tank. IIRC, propane tanks are not anchored so they can float. I hear that nasty things happen when propane comes in contact with water. If the tank is allowed to float, that reduces the chance that flood water will overflow the tank and get inside. Do you still think it's cool? (Don't take that as a personal atttack, I'm just asking.) If that thing had blown, we'd be looking at a whole different damage pattern!
I'm not sure how all this affects the EF ratings, but I thought these might be some important details to consider.
And yeah, I agree with you Greg that this probably has ALOT to do with poor construction. You don't lose your roof in a borderline cat 1-2 hurricane with a few isolated gusts to cat 3 unless it was barely on in the first place.
Greg Higgins
BTW, first picture, stright line winds, roof was not anchored properly.
First off, this is really going to be a rough assessment because of the aerial shots...really need to be on the ground for the absolute accurate and best rating. Second, this is just my personal opinion based on 1 year experience doing damage surveys.
Pic #1: Have to wonder about the integrity of the roof since it's completely gone. I don't know what the window situation was on the away side of the house...but if there were large windows blown out there, the walls on the toward side of the house probably didn't stand a chance...same goes for the roof too. Amazing, as it looks like the vegetation around the house hung tight but the power poles are knocked down. The debris didn't go far downstream either. Given all that and not knowing construction quality, I would go weak EF-1 (winds less than 95 mph), the vegetation looks too good to go higher and I wonder on the quality of construction.
Pic #2: Looks to be pretty good vegetation damage with some trunks snapped around the house. Other flattened vegetation to the top-side of the house. Leaning power pole and looks to be an outbuilding that looks to have just collapsed and the debris stayed put. The gas tank rolled is cool (just my opinion). Have to really wonder what was keeping this roof on this house (gravity?). The house held out fine. Given the questionable attachment of the roof, the tree in bottom center that looks to have held fine with other trees beaten up, I would go EF-1 (winds 95-105 mph).
And these pics are aerial surveys after Hurricane Humberto. It appears that mostly everything was straight line wind, and the NWS noted that in their final report. I wouldn't doubt a small tornado here and there though with the odd pattern of damage.
The NWS didn't focus on the house damage in their report, mostly power lines, vegetation, and a gas station, so this info is great for the paper I'm writing. I'm trying to ascertain what the peak gusts were in Humberto (for a small part of the paper at least).
BTW, what is your organization so I can give you proper credit?
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