ATL: IRMA - Post-Tropical - Discussion

[Kazmit]

Anguilla webcam. Some pretty large swells already pushing water all the way up the beach.

https://www.earthcam.com/world/anguilla/meadsbay/?cam=barnesbay

[plasticup]

And what makes it bad in a hurricane is that those winds are constant for a longer period of time, so more structures end up failing under those conditions.

185mph is a mid-range EF3 tornado. EF4 begins at 208mph.

http://www.spc.noaa.gov/faq/tornado/ef-scale.html

Those MPH numbers are for the old F scale the newer EF scale has EF5 being estimated as over 200MPH and it's a damage scale not a wind scale where winds are estimated based on damage.
Mark

They are also estimating maximum gusts (3 seconds), not sustained wind speed (1 minute or 10 minute). If Irma were a tornado she would likely be an EF5... and a few hundred miles wide.

[Shuriken]

I hear you, Shuriken, but I've never seen a storm maintain that level of intensity for very long, in 60 years of "watching" them.

Allen, David, Mitch. They all went "hard" cat-5 and stayed that way for long periods of time without further eyewall replacement cycles. (And Isabel, even though it bounced around a lot in intensity, never underwent another EWRC after achieving a huge eye.) The structure of these storms, especially those with larger eyes, becomes quite stable and impervious to otherwise deleterious atmospheric effects.

Allen went through a bunch of ERC's in the Caribbean (it fluctuated in intensity a lot - check the BT).

I watched Allen in real-time back in '80. Once at the top end with a mid-sized eye, that eye was not replaced.

David slammed into Hispaniola shortly after it attained Cat 5 status.

David was a steady-state cat-5 for 36 hours before hitting Hispaniola:

20 16.00 -64.20 08/30/06Z 140 925 HURRICANE-5
21 16.30 -65.20 08/30/12Z 145 924 HURRICANE-5
22 16.60 -66.20 08/30/18Z 150 924 HURRICANE-5
23 16.80 -67.30 08/31/00Z 145 927 HURRICANE-5
24 17.00 -68.30 08/31/06Z 145 928 HURRICANE-5
25 17.20 -69.10 08/31/12Z 145 927 HURRICANE-5
26 17.90 -69.70 08/31/18Z 150 926 HURRICANE-5

(David had a longer contiguous span of "being cat-5" than any storm in the modern era aside from Mitch, which was cat-5 for 42 contiguous hours.)

Mitch upwelled itself to death.

Mitch remained a steady cat-5 despite being almost stationary over the northwestern Caribbean for over 24hours, where deep-isothermic heat-content represents an almost inexhaustible fuel source for hurricanes. Mitch finally weakened when it drifted nearer the mountainous terrain of Honduras (which it eventually hit).

[OntarioEggplant]

You can actually see what will become a second eyewall starting to come together in that next spiral band on microwave imagery. The sad part is that it is a long way off from doing so, and it most certainly will not weaken before it hits Antigua

[Macrocane]

This is why I don't like to use pressure to classify hurricanes strenght.
Irma is in the top 5 of strongest hurricanes, period

There has been a recent trend worldwide about strongest tropical cyclones per basin (estimated or actually measured):
-Haiyan 2013 in the WPAC
-Patrica 2015 in EPAC
-Fantala 2016 in Sout Indian
-Winston 2016 in SPAC
-Could Irma be the one for the Atlantic?

[wxmann_91]

Allen, David, Mitch. They all went "hard" cat-5 and stayed that way for long periods of time without further eyewall replacement cycles. (And Isabel, even though it bounced around a lot in intensity, never underwent another EWRC after achieving a huge eye.) The structure of these storms, especially those with larger eyes, becomes quite stable and impervious to otherwise deleterious atmospheric effects.

Allen went through a bunch of ERC's in the Caribbean (it fluctuated in intensity a lot - check the BT).

I watched Allen in real-time back in '80. Once at the top end with a mid-sized eye, that eye was not replaced.

David slammed into Hispaniola shortly after it attained Cat 5 status.

David was a steady-state cat-5 for 36 hours before hitting Hispaniola:

20 16.00 -64.20 08/30/06Z 140 925 HURRICANE-5
21 16.30 -65.20 08/30/12Z 145 924 HURRICANE-5
22 16.60 -66.20 08/30/18Z 150 924 HURRICANE-5
23 16.80 -67.30 08/31/00Z 145 927 HURRICANE-5
24 17.00 -68.30 08/31/06Z 145 928 HURRICANE-5
25 17.20 -69.10 08/31/12Z 145 927 HURRICANE-5
26 17.90 -69.70 08/31/18Z 150 926 HURRICANE-5

(David had a longer contiguous span of "being cat-5" than any storm in the modern era aside from Mitch, which was cat-5 for 42 contiguous hours.)

Mitch upwelled itself to death.

Mitch remained a steady cat-5 despite being almost stationary over the northwestern Caribbean for over 24hours, where deep-isothermic heat-content represents an almost inexhaustible fuel source for hurricanes. Mitch finally weakened when it drifted nearer the mountainous terrain of Honduras (which it eventually hit).

Fair enough about David. 36 hr is a long time.

Kinda surprised about Allen though. Even the wiki article mentions ERC's. https://en.wikipedia.org/wiki/Hurricane_Allen I'd always imagine it kinda like Ivan, which did maintain an eye throughout, but fluctuated due to ERC's quite a bit.

After Mitch the waters of the NW Caribbean cooled quite a bit. No question a Cat 5 sitting in the same location for over 24-hr will start upwelling even in bath waters like the NW Caribbean.

[JPmia]

Anyone in Miami-Dade County can use this storm surge simulator map created by FIU and Miami-Dade County:

http://frances-a.cs.fiu.edu/gic/

[utweather]

Allen, David, Mitch. They all went "hard" cat-5 and stayed that way for long periods of time without further eyewall replacement cycles. (And Isabel, even though it bounced around a lot in intensity, never underwent another EWRC after achieving a huge eye.) The structure of these storms, especially those with larger eyes, becomes quite stable and impervious to otherwise deleterious atmospheric effects.

Allen went through a bunch of ERC's in the Caribbean (it fluctuated in intensity a lot - check the BT).

I watched Allen in real-time back in '80. Once at the top end with a mid-sized eye, that eye was not replaced.

David slammed into Hispaniola shortly after it attained Cat 5 status.

David was a steady-state cat-5 for 36 hours before hitting Hispaniola:

20 16.00 -64.20 08/30/06Z 140 925 HURRICANE-5
21 16.30 -65.20 08/30/12Z 145 924 HURRICANE-5
22 16.60 -66.20 08/30/18Z 150 924 HURRICANE-5
23 16.80 -67.30 08/31/00Z 145 927 HURRICANE-5
24 17.00 -68.30 08/31/06Z 145 928 HURRICANE-5
25 17.20 -69.10 08/31/12Z 145 927 HURRICANE-5
26 17.90 -69.70 08/31/18Z 150 926 HURRICANE-5

(David had a longer contiguous span of "being cat-5" than any storm in the modern era aside from Mitch, which was cat-5 for 42 contiguous hours.)

Mitch upwelled itself to death.

Mitch remained a steady cat-5 despite being almost stationary over the northwestern Caribbean for over 24hours, where deep-isothermic heat-content represents an almost inexhaustible fuel source for hurricanes. Mitch finally weakened when it drifted nearer the mountainous terrain of Honduras (which it eventually hit).

Once storms get large enough perhaps they can take on a life of their own. How large is an unknown of course.. https://www.space.com/23708-jupiter-gre ... evity.html

[KWT]

Exceptional hurricane, I had a feeling a cat-5 was quite possible (I remember talking about cat-5 a good 4-5 days ago now) but even so it really has taken on an exceptional presentation today and I'm floored by how powerful it is at the moment. The large eye is one of the best I've seen in the Atlantic!

[Langinbang187]

I can't wait for the next Recon. Wonder if this can break Allen's record.

[CryHavoc]

How intense do you guys think this could become before it just isn't scientifically possible for it to get any stronger? I mean there has to be a threshold right. Have there been any thesis or papers written considering how physically possible it is for a cyclone to become?

Much depends on ocean warmth. We have records of a storm from the 1780s that "stripped the bark off trees" which is not something that we have observed with any modern hurricanes, indicating gusts of over 200mph.

Patricia hit 215mph and might have been stronger. And some argue that Haiyan's presentation at peak was superior to that of Patricia, but sadly we don't have records from the center of the storm when he was at his apex. Estimates on his central pressure were as low as 858mb which could easily hold 200+mph winds.

The eye wall currently has winds similar to a moderate EF-4 tornado. 185 mph is ridiculous.

I believe tornadoes are rated based upon the gusts (please correct me if wrong). Thus, the winds are EF5 strength now

And what makes it bad in a hurricane is that those winds are constant for a longer period of time, so more structures end up failing under those conditions.

It is certainly terrifying, but please don't conflate tornadic winds with hurricane winds. There is a strong updraft component to tornadoes that makes their damage much more considerable to well-constructed housing, as a hurricane's winds are mostly horizontal. The "lifting" of a tornadic wind is responsible for a large portion of the damage it does.

Also, the Enhanced Fujita scale is not a wind scale, it's a damage scale. It's always an estimate of winds after the fact. In some regards it's much more limited than the S-S Scale because it tops at around 205mph when we have reliable data that tornadoes can have wind speeds of 300+.

[Extratropical94]

Does anyone know why the NOAA and USAF low-level missions are going on simultaneously and then there's like a 6 hour gap between center fixes? Wouldn't it make more sense to send in the planes one after another to have continuous coverage?

[Michele B]

185mph is a mid-range EF3 tornado. EF4 begins at 208mph.

http://www.spc.noaa.gov/faq/tornado/ef-scale.html

Those MPH numbers are for the old F scale the newer EF scale has EF5 being estimated as over 200MPH and it's a damage scale not a wind scale where winds are estimated based on damage.
Mark

They are also estimating maximum gusts (3 seconds), not sustained wind speed (1 minute or 10 minute). If Irma were a tornado she would likely be an EF5... and a few hundred miles wide.

THIS is what is freaking me out!

[Shuriken]

...It is certainly terrifying, but please don't conflate tornadic winds with hurricane winds. There is a strong updraft component to tornadoes that makes their damage much more considerable to well-constructed housing, as a hurricane's winds are mostly horizontal. The "lifting" of a tornadic wind is responsible for a large portion of the damage it does.

The winds in either are mainly lateral. Extreme winds blow into the weakest part of a structure, inflate it like a balloon until the roof lifts off and is whisked away. Integrity comprised, the rest of it is then easily torn apart.

Be that as it may, the eyewalls of very intense hurricanes contain updraft vortices on par with tornadoes: The "Great Hurricane of 1780" debarked trees and lifted iron cannon into the air. It demolished stone forts. (And this occurred on the weak side of that storm!)

[ObsessedMiami]

Miami Dade schools closed Thursday and Friday

[Sanibel]

Euro just put a bulls-eye on Sanibel of a 933 hurricane...


Headed to Costco and Home Depot...

[Evenstar]

And what makes it bad in a hurricane is that those winds are constant for a longer period of time, so more structures end up failing under those conditions.

185mph is a mid-range EF3 tornado. EF4 begins at 208mph.

http://www.spc.noaa.gov/faq/tornado/ef-scale.html

Those MPH numbers are for the old F scale the newer EF scale has EF5 being estimated as over 200MPH and it's a damage scale not a wind scale where winds are estimated based on damage.
Mark

Either one will rip a hole in your personal space-time continuum...

[Chris_in_Tampa]

From earlier Air Force recon mission:

[Evil Jeremy]

Miami Dade schools closed Thursday and Friday

Broward likely to follow suit shortly.

[Evenstar]

Those MPH numbers are for the old F scale the newer EF scale has EF5 being estimated as over 200MPH and it's a damage scale not a wind scale where winds are estimated based on damage.
Mark

They are also estimating maximum gusts (3 seconds), not sustained wind speed (1 minute or 10 minute). If Irma were a tornado she would likely be an EF5... and a few hundred miles wide.

THIS is what is freaking me out!

I join you in your freakage. I cannot begin to imagine the horror of it.