ATL: IDA - Remnants - Discussion

[mrbagyo]

Most roofs in Grand Isle remained intact
https://storms.ngs.noaa.gov/storms/ida/index.html#18/29.22876/-90.00318

[Blinhart]

Most roofs in Grand Isle remained intact
https://storms.ngs.noaa.gov/storms/ida/index.html#18/29.22876/-90.00318

Look at the whole Island, not just that one section. The whole island has been put as uninhabitable, and they don't know when it will be able to go back.

[Sanibel]

S2K member "Montegut" got the full impact from Ida...They are going through it right now with no utilities and a wrecked house...Montegut LA was in the west eye...


Ida damaged the pipes that deliver oil from the offshore platforms...There's an oil spill in the Gulf just south of the Mississippi outlet...

New York City is just starting to realize the impact of Ida with its torrential flooding, property damage and deaths...

The intact houses on Grand Isle are an illusion...The barrier Island had severe damage from Ida's east eyewall...

[LARanger]

So still no word on LSU2001? I saw that the user's last post was after the power went out but has been silent since then. Hopefully it's just waiting until the power is restored.

For anyone skimming this thread later and wondering, he's good.

viewtopic.php?f=59&t=102784&p=2939817&hilit=lsu2001#p2939817

[Category5Kaiju]

 https://twitter.com/islivingston/status/1436326272104288257




Welcome to the horror club, Ida.

*I have a nasty gut feeling that this map will eventually become obsolete in the next couple of years and that it will be to a point where significant overlap between Cat 4+ CONUS landfalls along the Gulf will make it hard to individually discern the individuals storms*

[Nancy Smar]

 https://twitter.com/ZackFradellaWx/status/1438989640128684037

[ncforecaster89]

https://twitter.com/ZackFradellaWx/status/1438989640128684037?s=20

Albeit an impressive wind gust to be measured by any instrument, it’s important to analyze it within its proper context.

First, this was an instantaneous gust (far exceeding what the standard 3 second gust value would be) and not representative of an official wind gust measurement.

Secondly, the anemometer height is being reported to have been at 100 feet elevation; which far exceeds the standard recording height of 10 m (33 ft).

Thirdly, we have no idea of said anemometers ability to accurately measure a wind speed of such extreme velocities. For example, there was a 3 second wind gust of 212 mph measured during hurricane Andrew. After it was analyzed and properly calibrated, the wind gust was revised downwards to 177 mph.

All the aforementioned aside, there’s no data supportive of Cat 5 designation at Ida’s peak intensity (around 3.5 hours prior to first LA landfall), much less when it reached the coast. In short, I’d set the early morning peak intensity at 135 kt followed by 130 kt at the Port Fourchon landfall.

[Audrey2Katrina]

Just wanted to check in. Rode out Ida; but had to evacuate because my area was hit pretty hard and at my age and health--couldn't stay without power for weeks. Glad to be back, and I really don't care if nobody sees this; I wanted to find an Ida thread so I could at least check in!

[cycloneye]

Great video by Josh.

 https://twitter.com/iCyclone/status/1445522221208727560

[ncforecaster89]

To better understand (determine) how that 223 mph instantaneous wind gust corresponds to a one-minute sustained wind speed at standard height…one can use the power law to covert from that 30 meter height to 10 meters elevation.


First, we need to convert the instantaneous gust to a 1-minute sustained wind speed. Extensive research

https://www.yumpu.com/en/document/view/ ... -from-1-/3

has shown that an instantaneous wind gust can be converted to a 1-minute wind speed by a factor of 1.45. In this case, it would translate to 154 mph.

Then, we’ll simply use the power law equation to extrapolate the aforementioned 154 mph wind at 30 m to a 10 m equivalent. To do so accurately, you need to utilize the appropriate surface roughness length. In this case, I’m using 0.10 for open ocean.


This converts to a 139 mph (120 kt) one minute sustained wind value. That’s a very impressive in-situ measurement to be captured at landfall in Port Fourchon.


Given its highly unlikely that any anemometer would be positioned perfectly to capture the highest wind speed in the eyewall, and taking into account that the strongest winds were likely found just to the E…this measurement provides excellent additional support for the operational intensity of 130 kt.