Major Hurricane Irma

[yoda]

Irma moving NW at hr 48

[RUNNAWAYICEBERG]

It's practically splitting 18z and 12z runs so far.

[Wow]

A bit east of 18z position at 48.

[Msalgado]

I'll be very intersted to see how large the eye is after the EWRC is complete.  It seems to be much larger via MW imagery.

[Hoosier]

00z GFS could end up slightly east, but it's not handling the northeast trough like the NAM.  If anything, it may be slightly more progressive with it compared to the last run.

[donsutherland1]

The GFS is running a shade to the north and east of its 18z run. It is running well to the south and west of the NAM, which should put to rest the speculation concerning the NAM.

Differences with the NAM:

24 hours: About 30 miles (SW of the NAM)

36 hours: About 70 miles (SW of the NAM)

48 hours: About 130 miles (SW of the NAM)

Between 9/8 12z and 9/9 0z, the GFS shows Irma's central pressure falling by 28 mb.

[DopplerWx]

at 63 looks like a direct landfall over miami. a tick east of 18z.

[40/70 Benchmark]

GFS is coming a bit ne, but its noise-

[jojo762]

1 minute ago, Msalgado said:

I'll be very intersted to see how large the eye is after the EWRC is complete.  It seems to be much larger via MW imagery.

Final step in the EWRC will be the shrinking of the new eye. Probably 25% or so larger nonetheless.

[dbullsfan]

does anybody think that the second turn to the NW can occur a little sooner possibly and skirt the pa  handle or possible even re-enter the golf and have a 2nd lf along the gulf coast. It seems the models are getting closer and closer to this possibility each run. 

[Rtd208]

Another DT (WxRisk) Irma update.

https://www.wxrisk.com/its-florida-and-miami-is-in-big-trouble/

[jm1220]

Models are really keying in on the period before landfall in SE FL for another round of strengthening. Hopefully that's wrong. I guess shear won't get to it until it's too late. 90F bath water in that area will allow it to go kaboom if other conditions allow. 

[NJwx85]

You know what....not much difference at h5 between the NAM and GFS hours 54-60. The problem is that the NAM is too far North compared to reality which puts it in a better spot to get picked up than reality.

[bdgwx]

2 minutes ago, Msalgado said:

I'll be very intersted to see how large the eye is after the EWRC is complete.  It seems to be much larger via MW imagery.

That's really old. Here's the latest. As you can see the ERC is nearly complete.

[Wow]

Def trying to hang back some energy to phase in over the MA

[CheeselandSkies]

Down to 897 at hour 54. Almost certainly overdone but it's just about inevitable that Irma will be at minimum a solid Cat 4 upon landfall, barring a miracle unforeseen by any model.

[Buckeye05]

Apologies if this is banter, but I've been looking through damage pics and videos of the Tortola damage, and there is legitimate debarking of trees. I have never seen that before with tropical cyclone damage. I've seen a lot of defoliated trees that were misidentified as debarked trees in past events, but never the real deal like this time with Irma. This storm is a completely different animal. 

[TPAwx]

This is still a horrific run for MIA and SE FLA.  Massive surge and wind impacts.

[Jaguars]

Oh South Florida my childhood home.  Not looking good.

[jburns]

17 minutes ago, ny10019 said:

hate to think of what will happen near Lake Okeechobee, too. Not a lot of talk about that, but somewhat similar to the Okeechobee Hurricane back in the 20's (albeit now they have better levee systems) I suspect there will still be quite a surge there also.  

Not much better. this is from a risk assessment report by Lloyd's.  That explains the spelling if dike(dyke).

 

Potential for dike failure of the Herbert Hoover Dike

 

In the 1970’s, the decision was taken to increase the upper limit of water in the lake from 15.5 feet to 17.5 feet.

And this brings us to the key concern; the dyke is no longer being used solely as a levee to protect the area from flooding when storms are in the vicinity but also to hold a permanent reserve of water. The lake is being used as a reservoir and therefore the dyke is now operating as a dam.

This means that water is pushing against the dyke nearly all of the time and that the risk does not come solely from a hurricane event. The dyke must act like a normal reservoir, i.e. be able to safely store floodwaters without overtopping.

The dyke was built from un-compacted earth, made up of naturally porous materials such as peat, gravel, sand and shell and is therefore prone to leaks. Since the construction of the dyke, the land outside of the dyke has been eroding, particularly on the south side of the lake.

The Herbert Hoover Dike, when built, was never intended to be used in this way and it has only recently been designated to be a dam. The flood criterion for dams is far more stringent than that which it has previously been subject to and also to which it is currently able to meet.

In their Expert Review Panel Report, prepared for the South Florida Water Management District in 2006, Bromwell, Dean and Vick describe the basic problem facing the dyke to be “simple”. They say:

“Certain geologic formations that underlie the dyke, and portions of the material that comprise it, bear a striking resemblance to Swiss cheese. Laced with interconnected voids and open channels, not only do these materials conduct large flows of water, they also admit sand and silt-sized soil particles that comprise the bulk of the dyke and its foundation. In a process of unstable feedback called internal erosion or piping, this seepage causes more particles to be removed, which in turn causes more seepage. Eventually, either excessive water pressures cause the dyke slopes to fail, or the dyke simply collapses from the net effect of particle removal one grain at a time. Herbert Hoover Dike has narrowly escaped failure from this process on several occasions and we suspect that its condition may be worsening.”

The situation is exacerbated by the erosion of the land outside of the lake. In this respect Bromwell commented to the Floridian press: “The important factor is the seeping going from the lake to the land side. The lower the land side, the greater the difference and the greater the seeping is.”

[78Blizzard]

The 00z GFS was virtually identical to 18z at landfall.  The gap between it and the NAM really started to widen at hr 54.

[psv88]

Does the eye come inland on the GFS?

[Msalgado]

3 minutes ago, bdgwx said:

That's really old. Here's the latest. As you can see the ERC is nearly complete.

 

Not sure why the full gif I linked isn't showing, but yeah, the last frame of the the gif is the scan you posted.  

[Hoosier]

2 minutes ago, NJwx85 said:

You know what....not much difference at h5 between the NAM and GFS hours 54-60. The problem is that the NAM is too far North compared to reality which puts it in a better spot to get picked up than reality.

I don't know... I'd say that's a *fairly* significant difference in handling the trough considering the relatively short lead time

[David-LI]

I'm hoping for a NAM solution or this will be a complete disaster. 

[NJwx85]

1 minute ago, psv88 said:

Does the eye come inland on the GFS?

Yes, near Marathon Key and then right up US-1.

[TPAwx]

Riding right on the FLA east coast.  This is an awful run and will be terrible for GA/western SC.

[DopplerWx]

hugging the fl coast thru 84, maybe a tick faster than 18z but pretty close.

[winterymix]

Even though GFS brings the core across Miami and straddles the coast, the pressure drops a bit

per GFS from around 970 mb to 967 mb. 

[Ginx snewx]

This is full of lots of woah