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NJwx85

Major Hurricane Irma

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1 minute ago, toller65 said:

Im done posting. If you go back thru the chain of posts, my response was to a statement that surge was not a big concern in Miami. I believe that it is, which appears to agree with your sentiment as well, so why ask the anger. GFY

Sent from my SM-G900V using Tapatalk
 

I think he quoted the wrong person.

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1 minute ago, toller65 said:

Im done posting. If you go back thru the chain of posts, my response was to a statement that surge was not a big concern in Miami. I believe that it is, which appears to agree with your sentiment as well, so why ask the anger. GFY

Sent from my SM-G900V using Tapatalk
 

He didn't mean to respond to your post, Toller, he was responding to the post that you were also responding to about Irma not having dangerous impacts on Miami if taking the EURO OP track.

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Well Don you have to take the bad with the good in a sick perverse way i find this challenging but these events are life changing my family voted and were staying but overall i love the fla lifestyle. This is not like preparing for a snowstorm thats for sure milk and bread isn't gonna cut it. we 've doing storing goods and gas since june just like any good weather weenie would .see ya

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1 minute ago, mulen said:

Well Don you have to take the bad with the good in a sick perverse way i find this challenging but these events are life changing my family voted and were staying but overall i love the fla lifestyle. This is not like preparing for a snowstorm thats for sure milk and bread isn't gonna cut it. we 've doing storing goods and gas since june just like any good weather weenie would .see ya

If you are in an area under mandatory evacuation, I highly encourage you to follow orders. 

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1 minute ago, SnowGoose69 said:

At first glance they look pretty far west to me 

The mean ends up just a tick East of the OP. 

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I think the thing that surprises me the most with Irma is the complete lack of ERCs at Cat 5 intensity for so long. It would be fascinating to understand why it's not happening so regularly. 

She's been going through quite a few ERC, from what I've seen anyway.
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4 minutes ago, SnowGoose69 said:

18Z hurricane models definitely are slightly more west than 12Z but nothing like the Euro

Time will tell if the Euro is on to something or if it's a one run thing.   Interesting as the rest of the models seems to be onto the previous Euro track.  Guidance would be pretty tight without the Euro deciding it wanted to leave the party just when everyone else was getting there.

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Just now, USCG RS said:
4 minutes ago, Master of Disaster said:
I think the thing that surprises me the most with Irma is the complete lack of ERCs at Cat 5 intensity for so long. It would be fascinating to understand why it's not happening so regularly. 
 

She's been going through quite a few ERC, from what I've seen anyway.

But I mean, when do you see a storm so well established that when it does go through one, the pressure continues to drop and the winds remain constant? If she is going through them, you def can't tell like most hurricanes. 

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2 minutes ago, Polka1 said:

Time will tell if the Euro is on to something or if it's a one run thing.   Interesting as the rest of the models seems to be onto the previous Euro track.  Guidance would be pretty tight without the Euro deciding it wanted to leave the party just when everyone else was getting there.

Yeah, we often see the GFS and CMC go to runs the Euro had 24-48 hrs earlier. Landfall should be in about 72 hrs and the Euro is leading the pack with about a 60 mile track error. 

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4 minutes ago, SnowGoose69 said:

At first glance they look pretty far west to me 

I deleted my message as they had just come out. The mean is west. I will look forward to seeing the individual members.

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Just now, bluewave said:

Yeah, we often see the GFS and CMC go to runs the Euro had 24-48 hrs earlier. Landfall should be in about 72 hrs and the Euro is leading the pack with about a 60 mile track error.

Which, it is worth noting, is about the width of southern Florida.

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But I mean, when do you see a storm so well established that when it does go through one, the pressure continues to drop and the winds remain constant? If she is going through them, you def can't tell like most hurricanes. 

I posted this last night...

OK.. So this has been bothering me the whole night. Therefore i spent the past three hours working and researching eyewall replacement cycle s (ERC) . I will preference with this: ERC are very poorly understood and research on them is just beginning. However, I found a theory about ERC which not only makes sense, but I was likewise able to extrapolate an answer for which I believe fits why these ERC are doing nothing to weaken Irma.

Terms:

ERC : Eyewall replacement cycle. HBL : Hurricane boundary layer. NRF : Net radial force. PGF : Pressure Gradient Force.

I will also preferance with the fact that I view weather as the earth's immune system and really all weather is is an attempt for the atmosphere to find an equilibrium (much like our immune system is to bring homeostasis to the body).

So let's get to it. ERC, in this theory, are believed to take place due to a set of complicated physics. As a hurricane is born, there are three main components, physics wise, which make up the storm (at least as it pertains to ERC). The first is the HBL which extends approximately 1 km into the atmosphere, from the surface. It interacts with most of the surface friction. The second is the PGF, which essentially forces particles from areas of higher density (pressure) to areas of lower pressure. The last is known as the NRF, which is essentially the force directed towards the center of a rotating mass.

As a hurricane develops, these forces work with each other and eventually, when the storm reaches a certain intensity, an excess of NRF creates a secondary wind maximum approximately 40-60km from the center of the hurricane. This secondary wind maximum is always believed to be because the HBL cannot properly maintain a balance of angular momentum (or the acceleration of particles/mass in a circulation motion), or in other words, the HBL cannot keep the particles separated in such a way that the pressure and buildup of particles remain uniform. This, combined with a positive NRF, creates convergence. This convergence creates an up welling which then leads to a secondary maximum. This secondary maximum, in turn, creates more PGF (the force of a particle over a given area. The higher the PGF, due to more particles in a smaller area, the higher the winds). Eventually, this leads to enough of a convergence that a secondary eyewall is formed and two wind maxima are thus created. As many know, during this time, the overall windspeed of the maximum sustained winds decrease due to the maximum winds being spread out over a larger area and thus the wind speed lowers (or.. The PGF is distributed over a larger area and therefore while the mass remains the same, because force equals mass times acceleration, acceleration is lower and therfore the force or net wind speed decreases). Eventually, the PGF, combined with angular momentum, will coerce the outer eyewall to contract, thus ending the ERC. At this time, the winds will increase as will the overall size of the wind field of the storm, while allowing the hurricane to likewise strengthen.

But the question that's plagues me today is why has Irma skipped this weakening phase of the ERC and likewise why has she been constantly cycling through them and having them take place in a rapid fashion? What I propose is this. Irma has been in essentially a perfect, or lab like environment, for her lifespan. This is what is allowing her to explosively deepen and shatter records. What I likewise propose us this. Irma is showing us that hurricanes create ERC of their own accord. In other words, an ERC has nothing to do with outside influences and is strictly because of the mechanism of the hurricane itself (and the strengthening mechanisms within). Likewise, because ERC are part of the hurricanes overall structure, in theory, it should not hurt the hurricane, but rather, help it. Left to its own devices, this is what Irma is doing. It's part of a necessary strengthening cycle for well developed hurricanes. The HBL, I propose, creates the issue for ERC as within this layer, there is friction. This friction slows the contraction of the secondary eyewall and forces the storm to balance itself out to preserve itself, while it deals with the friction and the effects of it. Because Irma is in a lab like environment, the friction of the ocean is essentially non existant as it is over flat and incredibly warm water. Likewise, there is no sheer or dry air to interfere with the Core and venting mechanisms of Irma. As such, these ERC can begin and complete without any interference and then, once the outer wind maxima are mature, the PGF and angular momentum can allow the outer wind maxima to contract, replacing the old eyewall and thus completing the ERC, in time for it to build and start once again. Therefore, she can bypass any weakening state that the friction within the HBL would cause, as, essentially, there isn't any to speak of.

This, of course, is strictly a theory
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Just now, JC-CT said:

Which, it is worth noting, is about the width of southern Florida.

Yeah, there is always going to be a margin of error no matter how good the model or group of models are. But we have come a long way in the last 20 or 30 years.

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Just now, bluewave said:

Yeah, there is always going to be a margin of error no matter how good the model or group of models are. But we have come a long way in the last 20 or 30 years.

We have. I am just pointing out that a west coast hit vs an east coast hit is within the average margin of error of the best performing model at this lead time.

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The thing to remember is there can be 30-40 mile errors at 24 hours.  St. Marteen for example was expected to be around 25 miles south of the eye at 24 hours out.  They ended up almost north of it.  That error wasn't noticeable to most people but an track error like that over florida will be 

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IR appearance is a little degraded the past hour. I wonder if the general circulation is feeling some effects from Hispañola. You can see some intense convection firing on the south side of the island in relation to southerly upslope flow associated with the outer reaches of Irma.

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19 minutes ago, donsutherland1 said:

In terms of intensity, even as the some of the guidance suggests weakening over the next 24-36 hours, Irma is forecast to traverse waters that have seen hurricanes intensify and sometimes rapidly. Both the GFS (>30 mb forecast deepening) and ECMWF (approximately 15 mb deepening) suggest that Irma could strengthen again as it approaches Florida. Such an outcome would also be consistent with historic climatology. For August-September hurricanes that did not make landfall on either Cuba and/or Hispaniola, 80% retained their strength or grew more intense as they crossed the waters of the Florida Straits (50% grew stronger).  Most of those storms deepened by 10 mb-15 mb.

Taking that into consideration, it still appears likely that Irma will be a Category 4 hurricane upon Florida landfall (best guess:  120 kts – 130 kts). There is some possibility that it could make landfall as a Category 5 storm.

Considering the potential for deepening that you discuss and the current maximum winds of 150kts I deduce you are expecting weakening at some point before the final approach to FL (assuming this favored track).  Do you see much possibility that the storm maintains it's current intensity or increases from here?  Another way to put it is how much confidence do we have in the weakening trend?  I haven't seen much discussion about shear, dry air, or land interaction or anything else that would typically weaken a hurricane, so wondering why this storm's wind's are expected to decrease?

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4 minutes ago, jviper said:

Which one of these model runs is the most consistent???

Out of those listed the blue lines. That's the UKMET. What's not listed is the ECMWF and the more reliable GEFS and EPS mean tracks.

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Size comparison between Andrew and Irma

Remains to be seen if it landfalls quite at Andrew's strength, but it's not at all hyperbolic to say there's potential for an impact many times worse.  If one of the really bad scenarios were to unfold, Irma may be a hurricane that is fresh in survivors minds even 50 years from now.

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3 minutes ago, SnowGoose69 said:

The Euro ensembles have maybe 10 members total near or east of the GFS and hurricane models track 

And about 10 members west of the Op. 

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35 minutes ago, AcePuppy said:

Latest model guidance

 

pQYePQ4.png

This would be a huge change considering SC is talking about evacuating the coast right now...

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23 minutes ago, JC-CT said:

We have. I am just pointing out that a west coast hit vs an east coast hit is within the average margin of error of the best performing model at this lead time.

Yeah, anyone in the official hurricane watch area should prepare as if they will see the worst that this storm has to offer.

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