ATL: HARVEY - Post-Tropical - Discussion

[txwatcher91]

There is an entirely different storm that the GFS and Euro hint at could develop in the western GOM in a few days. It may not happen but it's certainly something to watch out for, and the absolute last thing they need.

[tolakram]

Addicks continues to rise, even faster than earlier, probably due to massive runoff.

2109 8/29/2017 8:07 AM 108.12'
2109 8/29/2017 7:55 AM 108.10'
2109 8/29/2017 7:51 AM 108.09'
2109 8/29/2017 7:35 AM 108.05'
2109 8/29/2017 7:19 AM 108.01'
2109 8/29/2017 7:13 AM 107.99'

[KBBOCA]

There is an entirely different storm that the GFS and Euro hint at could develop in the western GOM in a few days. It may not happen but it's certainly something to watch out for, and the absolute last thing they need.

Oh, thanks. I hadn't heard about that. Definitely hope and pray it doesn't develop. Apologize for any misinformation.

[funster]

How is it staying higher than the top of the spillway? A surface tension effect? Hope there will be no erosion of the dam. https://www.harriscountyfws.org/GageDet ... surfaceBox

[KBBOCA]

The scale of this disaster keeps expanding... Unimaginable.

 https://twitter.com/BillyForney3/status/902519752064729088

[Extratropical94]

Press conference going on right now. Water management says they are not able to release the full 8000 cubic ft per second from Addicks and Barker because Buffalo Bayou is backing up into the release gates. That contributes to the quickly rising water levels in the reservoirs.
Also Barker is expected to reach the emergency spillway level if 104' on Friday.
Law enforcement is helping USGS scientists to get to the reservoirs to establish temporary flood sensors as the Barker gauge is flooded and not reachable. Addicks gauge might get flooded as well.

[jlauderdal]

Press conference going on right now. Water management says they are not able to release the full 8000 cubic ft per second from Addicks and Barker because Buffalo Bayou is backing up into the release gates. That contributes to the quickly rising water levels in the reservoirs.
Also Barker is expected to reach the emergency spillway level if 104' on Friday.
Law enforcement is helping USGS scientists to get to the reservoirs to establish temporary flood sensors as the Barker gauge is flooded and not reachable. Addicks gauge might get flooded as well.

whatever they are paying jeff lindner it isnt enough, this guy is clearly on top of his game and an excellent public speaker..nobody can claim confusion about what is happening, he tells you what he knows and tells you what is unknown, we need more of that

[Steve]

Interesting day here at work. The parking garage was empty, and schools were closed even though any threat issues here would be minimal. Nice band set up just south of the city almost all the way down to Central America. But it's pushing up overall to the NE, so maybe it doesn't stay around but for a few hours? Pumps are sketchy this year already, so hopefully that band just moves on eastward and whatever else we get pumped out of the Gulf in the next 30 or so hours isn't that big of a deal. Boss gave us the choice to work from home via laptop which I probably should have went ahead and gone for. I think people here are alert because we all have family and friends, not to mention many of you, over in SE Texas. Hope to see some of the mesoscale models clamping back on anymore onshore flow tonight into Jefferson County though.

[Extratropical94]

How is it staying higher than the top of the spillway? A surface tension effect? Hope there will be no erosion of the dam. https://www.harriscountyfws.org/GageDet ... surfaceBox

There is almost no water pressure pushing the water above the top of the spillway, so not a lot water will go down there with the level being just one or two inches above the height of the spillway. So currently there is still more water coming in than going out. The water level will rise untils the combined release from the controlled spillway gates and the uncontrolled emergency spillways equals the incoming water flow from runoff and rainfall.

Imagine pumping water into a bathtub with a fire hose. The water level in the tub will be a lot higher than its edges even though it will be constantly overflowing.

[Blinhart]

It has that subtropical/hybrid look this morning.

http://i.imgur.com/zLysk0T.jpg

To me it looks like he is trying to block off the dry air, one stubborn SOB

[PaulR]

Harris County monitors numerous gauges.

Addicks Reservoir is about to hit the spillway elevation. A spillway is generally a concrete structure that sits below the height of the dam (the ones I'm familiar with look like giant stepping stones) to allow water to flow out and not overtop the dam, which would lead to catastrophic failure. They started to do controlled water releases to try and avoid this but unfortunately the water levels have continued to rise.



2109 8/29/2017 6:47 AM 107.94' Spillway is 108'

Mark, does that mean when it goes over the spillway that the entire reservoir would breach and all that water would spill out or just the top-off?

The arrangement here is as complex as I've seen - granted that I've only looked at a tiny fraction of the reservoirs "out there". The sat view upthread from this post might well be relabeled "Main Dam", "Main (variable) Spillway", "Emergency Spillway #1", "Emergency Spillway #2", "Emergency Spillway #1a", and "Emergency Spillway #2a". It appears the intent is, in the event of catastrophic rainfall, to allow the emergency spillways to come into play in "stages". Basically, they protect the main dam in a situation such as we are seeing, by acting as relief valves.

The worry (aside from the "planned" increased discharge downstream) is erosion of an emergency spillway, such as was seen at Oroville (CA).

[tolakram]

The arrangement here is as complex as I've seen - granted that I've only looked at a tiny fraction of the reservoirs "out there". The sat view upthread from this post might well be relabeled "Main Dam", "Main (variable) Spillway", "Emergency Spillway #1", "Emergency Spillway #2", "Emergency Spillway #1a", and "Emergency Spillway #2a". It appears the intent is, in the event of catastrophic rainfall, to allow the emergency spillways to come into play in "stages". Basically, they protect the main dam in a situation such as we are seeing, by acting as relief valves.

The worry (aside from the "planned" increased discharge downstream) is erosion of an emergency spillway, such as was seen at Oroville (CA).

Here's the start of the north spillway, looking south. You can see the top lower and covered in concrete to prevent erosion if overtopped.

[SouthFLTropics]

Harris County monitors numerous gauges.

Addicks Reservoir is about to hit the spillway elevation. A spillway is generally a concrete structure that sits below the height of the dam (the ones I'm familiar with look like giant stepping stones) to allow water to flow out and not overtop the dam, which would lead to catastrophic failure. They started to do controlled water releases to try and avoid this but unfortunately the water levels have continued to rise.



2109 8/29/2017 6:47 AM 107.94' Spillway is 108'

Mark, does that mean when it goes over the spillway that the entire reservoir would breach and all that water would spill out or just the top-off?

The arrangement here is as complex as I've seen - granted that I've only looked at a tiny fraction of the reservoirs "out there". The sat view upthread from this post might well be relabeled "Main Dam", "Main (variable) spillway", "Emergency Spillway #1", "Emergency Spillway #2", "Emergency Spillway #1a", and "Emergency Spillway #2a". It appears the intent is, in the event of catastrophic rainfall, to allow the emergency spillways to come into play in "stages". Basically, they protect the main dam in a situation such as we are seeing, by acting as relief valves.

The worry (aside from the "planned" increased discharge downstream) is erosion of an emergency spillway, such as was seen at Oroville (CA).

While the concern for the reservoir is valid, I don't think you can make a comparison to the situation that happened at Oroville. The reason why is due to the differences between the two in regards to hydraulic engineering as well as the surrounding environment. Addicks and Barker are relatively flat areas whereas Oroville was an elevated reservoir. The flow of water over the spillway at Oroville had much more ability to erode the surrounding environment due to the height the water came from and the shear velocity that the water was flowing. With that said, any water that is flowing has the potential to cause severe erosion. That is likely to be seen at Addicks and Barker. I just don't think we will see it occur at the same rate or intensity as what we saw with Oroville.

[Tireman4]

Day 3...we are still good in the Atascocita Meadows Subdivision. We are 5.4 miles from Lake Houston and 7 miles from the San Jacinto River. The neighborhood is draining well. The core rains are moving out and we might get 3 to 5 inches total today, not the torrential downpours seen earlier. My heart aches for Southerngale and Beaumont. All of my family is ok. One cousin had to be rescued and is staying with her brother. My aunt had to evacuate from Dickinson last night. My Dad and Sisters are ok in Santa Fe

[Frank P]

looks like the NE turn is finally happening...

[stormreader]

still looks east to me, or perhaps just north of due east on the limited vis loops... should have been making that NE turn per all the model runs... not sure if any take it this far to the east... perhaps inland near south central LA coast? who knows

Local meteorologist says Cameron Parish.

The La landfall (probably Cameron Parish) does seem more likely. Interesting to see if this hybrid will come in at strong trop force strength (65 mph).

[vbhoutex]

Mark, does that mean when it goes over the spillway that the entire reservoir would breach and all that water would spill out or just the top-off?

The arrangement here is as complex as I've seen - granted that I've only looked at a tiny fraction of the reservoirs "out there". The sat view upthread from this post might well be relabeled "Main Dam", "Main (variable) spillway", "Emergency Spillway #1", "Emergency Spillway #2", "Emergency Spillway #1a", and "Emergency Spillway #2a". It appears the intent is, in the event of catastrophic rainfall, to allow the emergency spillways to come into play in "stages". Basically, they protect the main dam in a situation such as we are seeing, by acting as relief valves.

The worry (aside from the "planned" increased discharge downstream) is erosion of an emergency spillway, such as was seen at Oroville (CA).

While the concern for the reservoir is valid, I don't think you can make a comparison to the situation that happened at Oroville. The reason why is due to the differences between the two in regards to hydraulic engineering as well as the surrounding environment. Addicks and Barker are relatively flat areas whereas Oroville was an elevated reservoir. The flow of water over the spillway at Oroville had much more ability to erode the surrounding environment due to the height the water came from and the shear velocity that the water was flowing. With that said, any water that is flowing has the potential to cause severe erosion. That is likely to be seen at Addicks and Barker. I just don't think we will see it occur at the same rate or intensity as what we saw with Oroville.

Very good explanation of what we have here in Houston. The spillways on Addicks came into play early this morning unfortunately which means there is more flooding in neighborhoods East of the dam. At this point the flows are not of a magnitude that there will be massive erosion, or at least not that I am aware of yet. I haven't checked all my sources yet as I am just up. Overnight they doubled the area expected to be affected behind the dams due to watersheds literally overflowing into the ones behind the dams from further N and W of that area. The rains have slowed significantly on the N and W sides of the area, but have not stopped. I have had 28.14" at my house since this started and know that Bill Read has over 43" at his house closer to the coast and is expecting to go over 50". I wish these were fantasy figures but they are not.

[Frank P]

still looks east to me, or perhaps just north of due east on the limited vis loops... should have been making that NE turn per all the model runs... not sure if any take it this far to the east... perhaps inland near south central LA coast? who knows

Local meteorologist says Cameron Parish.

The La landfall (probably Cameron Parish) does seem more likely. Interesting to see if this hybrid will come in at strong trop force strength (65 mph).

Looks to be in that general heading provided he doesn't get anymore northerly component as many of the models have forecasted...

[artist]

Bush Airport closed til Thurs.
Edit: FAA says it is closed now indefinitely.
Houston Texans donating $1 million to a united Way

Artist where did you see the closed indefinitely notice from FAA? As the AIRPORT STATUS INFORMATION - HOUSTON AIRPORT - GEORGE BUSH INTERCONTINENTAL AIRPORT and FAA website are both still showing Thurs 31st noon reopening.
AIRPORT STATUS INFORMATION
provided by the FAA's Air Traffic Control System Command Center
George Bush Intercontinental/Houston Airport (IAH) Real-time Status
The status information provided on this site indicates general airport conditions; it is not flight-specific. Check with your airline to determine if your flight is affected.
Due to WEATHER/ HURRICANE HARVEY, the George Bush Intercontinental/Houston Airport (IAH) was closed as of Aug 27 at 10:24 AM CDT. The date/time when the airport is expected to reopen is Aug 31 at 12:00 PM CDT.
Delays by Destination:
Due to WEATHER/ HURRICANE HARVEY, the Southeast Texas Regional Airport (BPT) was closed as of Aug 28 at 06:50 AM CDT. The date/time when the airport is expected to reopen is Aug 29 at 07:00 AM CDT.
Due to WEATHER / HURRICANE HARVEY, the Houston William P Hobby Airport (HOU) was closed as of Aug 27 at 02:55 AM CDT. The date/time when the airport is expected to reopen is Aug 30 at 08:00 AM CDT.
Due to WEATHER/ HURRICANE HARVEY, the RAS airport was closed as of Aug 25 at 15:08 UTC. The date/time when the airport is expected to reopen is Sep 02 at 04:59 UTC.
Due to WEATHER/HURRICANE HARVEY, the SGR airport was closed as of Aug 27 at 23:33 UTC. The date/time when the airport is expected to reopen is Aug 29 at 23:59 UTC.
Due to WEATHER/HURRICANE HARVEY, the TME airport was closed as of Aug 28 at 02:33 UTC. The date/time when the airport is expected to reopen is Aug 30 at 23:59 UTC.
General Departure Delays: Traffic is experiencing gate hold and taxi delays lasting 15 minutes or less.
General Arrival Delays: Arrival traffic is experiencing airborne delays of 15 minutes or less.
This information was last updated: Aug 29, 2017 at 5:25 AM GMT
Glossary of Air Traffic Management Terms - A table containing definitions and/or descriptions of many common Air Traffic Management acronyms.
http://www.airport-houston.com/FAA.php

It was on KPRC. They first said til Thurs., went to break, came back, and apologized as they said they had heard from the FAA that both would be closed until further notice, and not opening on Thurs.

[Digital-TC-Chaser]

Interesting feature there was a small cyan ring too the ENE of Harvey over New Orleans.