ATL: DORIAN - Post-Tropical - Discussion

[CryHavoc]

You've also got to factor in not only the massive vertical component of tornadic winds lifting and carrying things, but also their rapid acceleration producing such a spike in wind loads that most structural elements can be overwhelmed. Long duration straight line winds are destructive but the lack of vertical component and the capacity to create a spiraling blender of debris tends to make hurricane winds of a similar speed less destructive, though much longer duration that may eventually cause structural fatigue.

But hurricanes have storm surge on their side which is a whole new horror altogether

Very true.

That being said there's no other weather phenomenon as widely destructive or costly as a hurricane. The combination of flooding, surge, and wind impacts over 100s if not 1000s of miles is unmatched.

Hurricanes are probably the most common, but volcanoes and tsunamis, when they rarely occur, are pretty hard to top. The 2011 Tohoku EQ & Tsunami is the most destructive natural disaster in history. Nothing really stops a wall of water.

Okay, I've been OT enough for the day. Back to watching Dorian.

[JaxBeachFL]

I see mentions after the latest euro run of possible shifts west in the next 24 hours. Since I’m less than a half mile inland in Jacksonville Beach this has peaked my interest. How close does the latest euro show dorian getting to Duval & St. John’s County? Local Mets here have been predicting a 90 mile pass to the east, east of 80W. Sounds like that may be shrinking.

[aperson]

Yeah the tree damage is going to be on a scale rarely witnessed... easily at or above Irma/Maria levels and I'm afraid we may have practically no surviving trees across Grand Bahama given the duration. I did an intense landfalling TC tree damage comparison a while back before even Michael and Dorian may easily top the list in the Atlantic; only a south Pacific storm or two may seriously rival it. EF3-4 tornado tree damage levels here with debarking.

Would that have long-term effects on erosion? I know that in some low-lying places the loss of foliage can lead to loss of land in the coming months/years.

Absolutely, vegetative stability prevents erosion due to soil stability, frictional wind dissipation, etc.... Losing mangroves will also cause storm surge impacts to be worse as they dissipate surge.

[Michele B]

You've also got to factor in not only the massive vertical component of tornadic winds lifting and carrying things, but also their rapid acceleration producing such a spike in wind loads that most structural elements can be overwhelmed. Long duration straight line winds are destructive but the lack of vertical component and the capacity to create a spiraling blender of debris tends to make hurricane winds of a similar speed less destructive, though much longer duration that may eventually cause structural fatigue.

But hurricanes have storm surge on their side which is a whole new horror altogether

I picture a hurricane as just a 78 rpm tornado "record" turned to 33 1/3 rpm (for those old enough to know what I'm talking about!)

[Aric Dunn]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

[CryHavoc]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

Wow, is that the eye reappearing? It's far to the NE and looks incredibly ragged. Thankfully the weakest Dorian has appeared to date, he's got a lot of work to do to reorganize.

[Michele B]

Yeah the tree damage is going to be on a scale rarely witnessed... easily at or above Irma/Maria levels and I'm afraid we may have practically no surviving trees across Grand Bahama given the duration. I did an intense landfalling TC tree damage comparison a while back before even Michael and Dorian may easily top the list in the Atlantic; only a south Pacific storm or two may seriously rival it. EF3-4 tornado tree damage levels here with debarking.

I remember a friend who went down to help with Andrew rescue said they were struck by the fact that not one tree left standing had a single LEAF on it. Just wind-whipped clean. That stayed with them for some reason.

[ScottNAtlanta]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

You can see on that loop how the center just popped over about 20 miles east

[aperson]

Impacts of upwelling visible in SSTs from the westward TPW fetch Dorian has had over the past 3 days


(ref: https://marine.rutgers.edu/cool/sat_dat ... gulfmexico)

[jdjaguar]

I see mentions after the latest euro run of possible shifts west in the next 24 hours. Since I’m less than a half mile inland in Jacksonville Beach this has peaked my interest. How close does the latest euro show dorian getting to Duval & St. John’s County? Local Mets here have been predicting a 90 mile pass to the east, east of 80W. Sounds like that may be shrinking.

The possible west shifts are more of a concern for Savannah and the Carolinas.

[Aric Dunn]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

You can see on that loop how the center just popped over about 20 miles east

thats not the center its a little gulp of dry air.

[Michele B]

Not really. Hurricane winds and torandic winds are not the same, and comparing them directly is inadvisable. FWIW you're also using the old Fujita scale -- 185mph winds on the new scale would be high end EF4.

In what ways is it wrong to compare hurricane and tornadic winds? How are they different?

Serious question.

To elaborate a bit on what aperson stated:

Tornadic winds and hurricane winds are very different animals. Hurricanes are warm core systems and are actually fairly stable with regard to changes in speed and altitude -- this is why hurricane hunter aircraft can fly through even cat4/5 hurricanes fairly safely.

Tornadoes form from cold core systems and as such one of their primary methods of wind movement is actually vertical -- this makes sense, considering that mature tornadoes are connected directly to the parent cloud/supercell. When a hurricane hits your house (assuming that it doesn't do so with an embedded spin up tornado!), the wind damage is caused by straight-line winds. In coastal cities more damage often occurs from storm surge than from actual winds. In strong/violent tornadoes, they (often) develop small circulation centers within the parent tornado that have extremely strong updraft components in the form of suction vortices -- some of these have wind speeds of 300+ mph, and they can actually lift the roof off of the house to drastically increase the rate of structural failure for the rest of the building. Once wind has a "grip" on a building (i.e., a part of the building fails that allows wind to channel to more areas rather than just the outside), the forces exerted by the wind speed increase tremendously.

Sorry for the OT explanation -- just thought it was important in light of the comments comparing Dorian to a tornado. They are both beasts, but beasts of a different sort. That said, the damage here does look incredible, and heart-breaking.

Thanks for the explanation!

"Warm-core" vs "cold-core", etc. Never knew that before!

As far as "updraft (suction) vortices....." I've experienced what I THOUGHT was that phenomena when all the water is sucked out of a toilet when the eye wall of a hurricane is directly overhead.

[psyclone]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

You can see on that loop how the center just popped over about 20 miles east

thats not the center its a little gulp of dry air.

yes. the center resides just west of there and is now obscured

[plasticup]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

Wow, is that the eye reappearing? It's far to the NE and looks incredibly ragged. Thankfully the weakest Dorian has appeared to date, he's got a lot of work to do to reorganize.

I don't think that's an eye, just a break in the convection.

[ScottNAtlanta]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

You can see on that loop how the center just popped over about 20 miles east

thats not the center its a little gulp of dry air.

As I've been looking at it...I believe you are correct.

[Michele B]

I see mentions after the latest euro run of possible shifts west in the next 24 hours. Since I’m less than a half mile inland in Jacksonville Beach this has peaked my interest. How close does the latest euro show dorian getting to Duval & St. John’s County? Local Mets here have been predicting a 90 mile pass to the east, east of 80W. Sounds like that may be shrinking.

Remember, too, the FL coastline doesn't run directly North and South. It turns more northwest at the northern part of the state (heading toward Jax), so I wouldn't think a slight nw turn would affect the overall consensus on the models.

But don't take MY word for it!!!

[Meteorcane]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

You can see on that loop how the center just popped over about 20 miles east

That is a dry slot and not the eye/center... that is located further SW.

[jhpigott]

Sebastian Inlet reporting sustained TS conditions

https://twitter.com/NHC_Atlantic

[northjaxpro]

I see mentions after the latest euro run of possible shifts west in the next 24 hours. Since I’m less than a half mile inland in Jacksonville Beach this has peaked my interest. How close does the latest euro show dorian getting to Duval & St. John’s County? Local Mets here have been predicting a 90 mile pass to the east, east of 80W. Sounds like that may be shrinking.

The 12Z EURO, if it verifes, could shift Dorian's eyewall as close to 50 -60 miles east of Mayport.

This type of shift could bring hurricane force wind gusts to the coast. This is what i am extremely closely watching and concerned as well.

[Vdogg]

Interesting change in the flow over NC and Tennessee looks like some mid to upper level ridging has developed as well as a little south into SC... could be what the EURO caught onto..

https://imgshare.io/images/2019/09/03/5.gif

Wow, is that the eye reappearing? It's far to the NE and looks incredibly ragged. Thankfully the weakest Dorian has appeared to date, he's got a lot of work to do to reorganize.

I don't think that's an eye, just a break in the convection.

But if you look at IR it appears that cloud tops are cooling and trying to encircle this dry spot. Are we sure that’s not an eye?