ATL: HARVEY - Post-Tropical - Discussion

[tolakram]

Live coverage for those wondering: http://abc13.com/live/

[Tireman4]

Live coverage for those wondering: http://abc13.com/live/

That is 5 to 6 miles from us. Kings River is one of the team's in our swimming league. We are up in elevation from there.

[tolakram]

New Orleans saved radar loop

[LAwxrgal]

Yep tolakram that's us, we're getting pounded atm. My street is flooded.

[ColdFusion]

With the Addicks Reservoir topping 108' right now, this image is really interesting as far as when and where the water will go at different elevations.
I do not know the source or accuracy of this image, just saw it on twitter....

[ace]

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.

Thanks, everyone, for the information. I'm in Spring in a miracle area surrounded by Cypresswood, 45 and Kuykendahl (and near 99\Grand Parkway). I'm also a teacher. Even if it's not a named storm **any** more rain here and we're going to have an even bigger problem.

[yzerfan]

The official FAA bulletin has reopening dates of Wednesday for Hobby and Thursday for IAH while the official airport twitter accounts for both of those describe the closure as indefinite. I'd assume that the FAA's reporting system does require an estimated reopening date, and that's why it's posted as such, but that the timeframe they're showing is a 'Not Earlier Than' rather than an expectation of the resumption of normal operations at the posted time and it's subject to being pushed out at any time.

[SueOrleans]

Yep tolakram that's us, we're getting pounded atm. My street is flooded.

Here in New Orleans it's been a steady, but not drenching, rain for at least the last three and a half hours. No sign of stopping, but our pumps seem to be keeping up so far. Good luck.

[stormreader]

Looks like Harvey may be just at the beginning of his turn back toward the NW gulf coast (as Frank stated). Exact angle it takes may mean the difference in huge amounts of rain for persons between Houston and Lake Charles (especially).

[PaulR]

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.

I agree with that, with an exception: While erosion at Addicks and Barker (spillways) should be slower, at Oroville they had the ability to go back to the main spillway when they saw the emergency spillway was in trouble, since the main spillway had a large capacity. Am I correct that such is NOT the case here?

Also... Am I looking at that picture correctly? There are trees in the emergency spillway / floodway, not too far from the top? That is NOT good. They can go over easily, creating erosion triggers, if you will, at the root balls. What one wants is unbroken, tough grass, with deep roots, regularly mowed. I pray crews got out there with chain saws...

[artist]

The official FAA bulletin has reopening dates of Wednesday for Hobby and Thursday for IAH while the official airport twitter accounts for both of those describe the closure as indefinite. I'd assume that the FAA's reporting system does require an estimated reopening date, and that's why it's posted as such, but that the timeframe they're showing is a 'Not Earlier Than' rather than an expectation of the resumption of normal operations at the posted time and it's subject to being pushed out at any time.

Thank you for that. They did state for IAH , other than for emergency use.

[PaulR]

Live coverage for those wondering: http://abc13.com/live/

Did those rescues abc13 was covering late last night go on all night? I know they said many of the rescuers that were still there around 1 a.m. were exhausted. Me too - I just had to sleep, and I was only watching!

[Blinhart]

I'm wondering this numbers I'm seeing for the reservoirs are they the height of the water above sea level instead of depth, because I can't see there being areas where they would have water 108 feet deep. I always thought it was the depth of the water not the height above sea level.

[hohnywx]

 https://twitter.com/BrazoriaCounty/status/902539081841827842

[PTPatrick]

HPC seems to following radar trend, official forecast track etc in keeping heaviest rain east Galveston bay at this point. I had mentioned NAM and GFS back a precip comma head into Houston tonight...they don't seem to be buying it and judging from radar trends they are proabably right.

From the disco:
MODELS SHOW
A BIT MORE SPREAD WITH THE LOCATION OF HEAVIEST RAINS ALONG THE
UPPER TX COAST WHICH IS PARTLY TIED TO DIFFERENCES IN HARVEYS
TRACK. THE 12Z EC AND 00Z GFS MOST CLOSELY FIT THE OFFICIAL 03Z
NHC TRACK..THOUGH IN THE CASE OF THE GFS..IT SEEMS TO BE TOO FAR
WEST WITH THE HEAVIER CORE OF RAINS ACRS THE UPPER TX COAST. THE
EXPERIMENTAL NSSL WRF AND EXPERIMENTAL ARW SEEM TO SHOW BOTH A
GOOD FIT TO THE OFFICIAL TRACK AND TIGHTER CORE AROUND THE WEST
SIDE OF THE CIRCULATION AND WERE GIVEN HIGHER WEIGHT. SOME
CONSIDERATION WAS ALSO GIVEN TO HRRR AND HRRR EXPERIMENTAL WHICH
KEPT HIGHER AMOUNTS A LITTLE EAST OF THESE MODELS. CONFIDENCE IS
NOT QUITE AS HIGH AS PREVIOUS DAYS GIVEN SOMEWHAT LARGER MODEL
SPREAD..SO DID NOT GO AS HIGH AS THE EXPERIMENTAL NSSL WRF AND ARW
RUNS WERE INDICATING...BUT STILL ARE INDICATING SOME EXTREME
AMOUNTS ONCE AGAIN NEAR AND EAST OF THE GALVESTON BAY REGION WITH
5 TO 9+" RAINS POSSIBLE. OVER THE CNTL GULF AREAL AVG AMOUNTS OF
2 TO 4+"

[hohnywx]

Terrible news out of Galveston County this morning:

 https://twitter.com/GalvNews/status/902539141992382464

[nascarfan999]

I'm wondering this numbers I'm seeing for the reservoirs are they the height of the water above sea level instead of depth, because I can't see there being areas where they would have water 108 feet deep. I always thought it was the depth of the water not the height above sea level.

Generally, I've seen a mix of both depending on the area, with lakes more likely to list their heights relative to sea level than rivers. In this specific case, I think, but am not 100%, that the heights listed are above sea level. Based on the gauge website, the bottom of the reservoir is at 67.8'.

https://www.harriscountyfws.org/GageDetail/Index/2110?span=24%20Hours&v=surfaceBox

[tgenius]

 https://twitter.com/BrazoriaCounty/status/902539081841827842

That is downright terrifying to see them post like that. Hopefully people are able to get out.

[txwatcher91]

 https://twitter.com/BrazoriaCounty/status/902539081841827842

Any ideas what areas this will affect, downstream and neighborhood wise?

[Extratropical94]

I'm wondering this numbers I'm seeing for the reservoirs are they the height of the water above sea level instead of depth, because I can't see there being areas where they would have water 108 feet deep. I always thought it was the depth of the water not the height above sea level.

Yes, in this case it is above sea level. Typically in low-lying areas the reference height, or "gage 0" datum is chosen to be sea level. As you get up to higher ground, different reference heights are chosen to avoid ridiculously high water levels (like 5000+ feet in Denver for instance). And as nascarfan999 already said, lakes are more likely to have their levels measured in ft above sea level.

On the USGS water level graphics you can see the reference datum at the bottom left.