ATL: HARVEY - Post-Tropical - Discussion

[wxman57]

I'm no pro, but the radar and infrared seem to be spinning in different locations. I suspect this will impede redevelopment.

What you're observing is Harvey's mid-level circulation (IR satellite) separated from the low-level circulation (radar). Yes, Harvey's core has been significantly disrupted over land. That will make it hard for Harvey to strengthen once it's back over the water.

[Callista]

Does opening the dam cut down on dangerous flash-flooding, then? If overtopping a dam is inevitable, it sounds like a less damaging way to let the water in at least.

[SunnyThoughts]

http://www.yourconroenews.com/news/arti ... 045042.php Yet MORE evacuations ordered due to rivers/dams

[ScottNAtlanta]

Any news on when the Red Cross is going to start sending teams in? I know they are operating shelters, of course. As far as I can tell it depends on when it's safe for relatively unskilled volunteers to respond, which as of now probably depends on the nature of the flooding?

Another question: CNN is reporting that they are deliberately opening up some dams, to let the floodwater through. What's the benefit of that, as opposed to keeping them up and hoping they hold?

Total failure of said dam.

On another forum they are saying some of these dams are among the top WORST ONES in need of repairs in the country, according to Army Corps of Engineers.

MORE infrastructure failure that will cost - hopefully only property, not lives.

...and they have only just started repairs on a few of them

[Snowman67]

I'm no pro, but the radar and infrared seem to be spinning in different locations. I suspect this will impede redevelopment.

What you're observing is Harvey's mid-level circulation (IR satellite) separated from the low-level circulation (radar). Yes, Harvey's core has been significantly disrupted over land. That will make it hard for Harvey to strengthen once it's back over the water.

Even if it stays disorganized, will it have the ability to pull in heavy rain bands off the gulf into the Houston Metro area?

[ScottNAtlanta]

Does opening the dam cut down on dangerous flash-flooding, then? If overtopping a dam is inevitable, it sounds like a less damaging way to let the water in at least.

They are good for short term or even midterm flood mitigation, but this is not an ordinary event

[Frank P]

to my grossly untrained eyes, looking at radar and the sat loops, they don't look "that" far apart... as always just premature speculation on my part...

[AdamFirst]

Looks like the dry slots are filling in with rain again as it moves back over water.

[gatorcane]

Judging by the radar, looks like Houston is seeing more training of bands as rain continues to come down over the city. What a mess this storm has caused.

[BZSTORM]

Is there an interactive map anywhere to help me locate a specific location in Houston that may or may not be inundated with water?

It's slightly south and west of Houston proper.

TIA

Harris country has the only interactive map I have been able to find doesn't show specific flooding but does show gauges data https://www.harriscountyfws.org/ there is alert page which might help you on the site as well

[Callista]

Nowhere near an ordinary event, yes.

Can one dam failure trigger others? Or would it relieve pressure on others, instead? I remember in the Great Flood of '93 on the Mississippi, practically all of the levees failed in one way or another, but I can't find any information about whether they tried opening them deliberately first. Of course, this wasn't a hurricane-caused event, so they started out with intact infrastructure rather than a lot of wind damage, and were able to do a lot of sandbagging to try to prevent the worst of it (whether it worked is debatable, but I can only imagine it must have been better than sitting helplessly doing nothing).

[artist]

Any news on when the Red Cross is going to start sending teams in? I know they are operating shelters, of course. As far as I can tell it depends on when it's safe for relatively unskilled volunteers to respond, which as of now probably depends on the nature of the flooding?

Another question: CNN is reporting that they are deliberately opening up some dams, to let the floodwater through. What's the benefit of that, as opposed to keeping them up and hoping they hold?

Put it this way, flood people out of the homes by opening the dams or completely submerge downtown Houston by keeping them closed.

And everything in between if they fail.

[Michele B]

Is there an interactive map anywhere to help me locate a specific location in Houston that may or may not be inundated with water?

It's slightly south and west of Houston proper.

TIA

Harris country has the only interactive map I have been able to find doesn't show specific flooding but does show gauges data https://www.harriscountyfws.org/ there is alert page which might help you on the site as well

Thank you! That did help.

It showed me exactly how much rain had fallen in the area I was inquiring about!

[ScottNAtlanta]

Nowhere near an ordinary event, yes.

Can one dam failure trigger others? Or would it relieve pressure on others, instead? I remember in the Great Flood of '93 on the Mississippi, practically all of the levees failed in one way or another, but I can't find any information about whether they tried opening them deliberately first. Of course, this wasn't a hurricane-caused event, so they started out with intact infrastructure rather than a lot of wind damage, and were able to do a lot of sandbagging to try to prevent the worst of it (whether it worked is debatable, but I can only imagine it must have been better than sitting helplessly doing nothing).

I recall during one of the big Mississippi floods they breached a levee that flooded farm land in order to keep levels from going over the levees down stream. Any levee failure will remove some pressure from the flooded river because levees by design are there to keep the channel narrow instead of letting the water spread to cover the flood plain.
A dam failure would most certainly risk failure down stream if there was another dam in addition to the catastrophic flooding that would occur at the breach.

[SunnyThoughts]

Mayor of Dallas on TWC right now news conference. They are preparing the "mega" evacuation center to be open tomorrow ( they hope it to be open earlier) they are expecting tens of thousands of evacuees.

[SunnyThoughts]

And to add insult to injury, there is now a building on fire in downtown Houston. Abc13.com has info for those interested It just doesn't stop.

[artist]

NBC Nightly News @NBCNightlyNews
·
4m
BREAKING: Texas governor activates the entire Texas National Guard, around 12,000 service members, to respond to #Harvey disaster.

[artist]

And to add insult to injury, there is now a building on fire in downtown Houston. Abc13.com has info for those interested It just doesn't stop.

Fortunately they got it out. Unfortunately onenfireman was rushed to the hospital. He was grabbing his head as he exited the building. Kprc said they would try to get an update on his condition.

[artist]

http://www.yourconroenews.com/news/article/Conroe-calls-for-major-evacuations-amid-record-12045042.php Yet MORE evacuations ordered due to rivers/dams

Kprc is showing a map of mandatory evacuation areas and it won't even feet the screen . The Judge is saying there may be further evacuations issued.

[nascarfan999]

Nowhere near an ordinary event, yes.

Can one dam failure trigger others? Or would it relieve pressure on others, instead? I remember in the Great Flood of '93 on the Mississippi, practically all of the levees failed in one way or another, but I can't find any information about whether they tried opening them deliberately first. Of course, this wasn't a hurricane-caused event, so they started out with intact infrastructure rather than a lot of wind damage, and were able to do a lot of sandbagging to try to prevent the worst of it (whether it worked is debatable, but I can only imagine it must have been better than sitting helplessly doing nothing).

I recall during one of the big Mississippi floods they breached a levee that flooded farm land in order to keep levels from going over the levees down stream. Any levee failure will remove some pressure from the flooded river because levees by design are there to keep the channel narrow instead of letting the water spread to cover the flood plain.
A dam failure would most certainly risk failure down stream if there was another dam in addition to the catastrophic flooding that would occur at the breach.

The basic premise for either a levee or a dam is that a breech, whether intentional or not, will relieve pressure behind/upstream from the location and enhance the pressure below/downstream from the location. With a levee it is more about filling in unflooded areas, but with a dam it is about where does that water go and are there more dams/levees downstream. If so, it can add even more pressure on them which could lead to a failure. Also, a failure can be many, many times worse than a controlled release. The below image is a good example of what a dam break can do to the landscape. Note that there is no sign of the forest that was previously there, just rocks and dirt. The below example (NOT current, from many years ago) had the added element of being on a mountainside and thus the water was gaining speed as it sped down the mountain, but I still think it underscores how important it is to ensure any releases are done in a controlled fashion.



Again, the above image is NOT of anything happening right now in Texas or elsewhere, but is simply an example of damage from a dam break.