ATL: FLORENCE - Post-Tropical - Discussion

[p1nheadlarry]

The NHC may be low balling the storm surge numbers. Cape Fear to Cape Lookout of 9 to 13 feet seems low.

Maximum surge potential for a Cat 3 can be 20 feet and Florence seems to be bigger and badder than your average Cat 3. Just curious how they decided on these numbers. Any pro mets care to comment?

https://www.wunderground.com/hurricane/surge/wilmington_mom3.png

Is this not for a Myrtle hit? A Wilmington hit would cause mostly offshore winds in SC

[p1nheadlarry]

I see some here (and elsewhere) celebrating that it won't be as bad because weakening--does the wind reduction even mean anything at this point given how high and large the surge area is likely to be?

If it hits at high tide the surge + expanded wind field is still a problem

[syfr]

I see some here (and elsewhere) celebrating that it won't be as bad because weakening--does the wind reduction even mean anything at this point given how high and large the surge area is likely to be?

For those of us not in the surge area, but who ARE in a heavily treed area, maybe yes.

[SouthFloridawx]

I think I figured out what's causing the weakening. There's an upper level low to the SW of the storm.

[northjaxpro]

I see some here (and elsewhere) celebrating that it won't be as bad because weakening--does the wind reduction even mean anything at this point given how high and large the surge area is likely to be?

If it hits at high tide the surge + expanded wind field is still a problem

It would potentially be a very substantial problem .

[RL3AO]

The NHC may be low balling the storm surge numbers. Cape Fear to Cape Lookout of 9 to 13 feet seems low.

Maximum surge potential for a Cat 3 can be 20 feet and Florence seems to be bigger and badder than your average Cat 3. Just curious how they decided on these numbers. Any pro mets care to comment?

https://www.wunderground.com/hurricane/surge/wilmington_mom3.png

Is this not for a Myrtle hit? A Wilmington hit would cause mostly offshore winds in SC

It's not for any hit in particular. It's a map that shows the highest possible storm surge when you run the model using every possible track, direction, and speed.

Use the NHC inundation map for an idea about what this storm will do. That map is for emergency management to develop evacuation zones and not to be used for a specific storm.

[Sciencerocks]

I think I figured out what's causing the weakening. There's an upper level low to the SW of the storm.

https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41705185_387610848443363_7397338464435306496_n.png?_nc_cat=0&oh=63fbfab0ea8e1f98133f82691eff9472&oe=5C32BC7A
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41628851_295062747987538_7855719476166131712_n.png?_nc_cat=0&oh=2806b52dfbeea7c0199a233d638a0c9a&oe=5C37CAA4
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41602498_686195115088049_4162816048564797440_n.png?_nc_cat=0&oh=bb66d565fc505e3dbd6ef8a42d981618&oe=5BEDFF09

Exactly, This upper low is forcing the dry air to the south into the core of this system. This won't allow it to restrengthen and will likely continue to weaken the cyclone.

[Ken711]

I think I figured out what's causing the weakening. There's an upper level low to the SW of the storm.

https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41705185_387610848443363_7397338464435306496_n.png?_nc_cat=0&oh=63fbfab0ea8e1f98133f82691eff9472&oe=5C32BC7A
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41628851_295062747987538_7855719476166131712_n.png?_nc_cat=0&oh=2806b52dfbeea7c0199a233d638a0c9a&oe=5C37CAA4
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41602498_686195115088049_4162816048564797440_n.png?_nc_cat=0&oh=bb66d565fc505e3dbd6ef8a42d981618&oe=5BEDFF09

Levi Cowan also explains this from about the 3:41 mark in his latest video.

https://www.youtube.com/watch?v=7vBtniLYSfM&t=519s

[psyclone]

I see some here (and elsewhere) celebrating that it won't be as bad because weakening--does the wind reduction even mean anything at this point given how high and large the surge area is likely to be?

I would imagine the extent of the windfield and the forward motion is far more important than the max winds. Moderate to strong wind over a big area is what really piles up the water...and is critical to building massive waves...which do the really dirty work at the shore once the water has risen. However...it is fair to say that the system looks far less impressive as compared to earlier

[p1nheadlarry]

The NHC may be low balling the storm surge numbers. Cape Fear to Cape Lookout of 9 to 13 feet seems low.

Maximum surge potential for a Cat 3 can be 20 feet and Florence seems to be bigger and badder than your average Cat 3. Just curious how they decided on these numbers. Any pro mets care to comment?

https://www.wunderground.com/hurricane/surge/wilmington_mom3.png

Is this not for a Myrtle hit? A Wilmington hit would cause mostly offshore winds in SC

It's not for any hit in particular. It's a map that shows the highest possible storm surge when you run the model using every possible track, direction, and speed.

Use the NHC inundation map for an idea about what this storm will do. That map is for emergency management to develop evacuation zones and not to be used for a specific storm.

Ah ok thanks.

[SouthFloridawx]

I think it appears that it's moving slight south of west. So, who knows. If the storm slows down it, the ULL could pull away from the system to be in more of a position to help ventilate it more, but I could be wrong.

I think I figured out what's causing the weakening. There's an upper level low to the SW of the storm.
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41705185_387610848443363_7397338464435306496_n.png?_nc_cat=0&oh=63fbfab0ea8e1f98133f82691eff9472&oe=5C32BC7A
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41628851_295062747987538_7855719476166131712_n.png?_nc_cat=0&oh=2806b52dfbeea7c0199a233d638a0c9a&oe=5C37CAA4
https://scontent-mia3-1.xx.fbcdn.net/v/t1.15752-9/41602498_686195115088049_4162816048564797440_n.png?_nc_cat=0&oh=bb66d565fc505e3dbd6ef8a42d981618&oe=5BEDFF09

Exactly, This upper low is forcing the dry air to the south into the core of this system. This won't allow it to restrengthen and will likely continue to weaken the cyclone.

[abajan]

Don't know if this update by Levi Cowan has been shared here yet.

[meriland29]

There is serious convection popping up...yet her eye is shrinking..i am so confused.

[Ken711]

Don't know if this update by Levi Cowan has been shared here yet.

I posted it 3 posts above yours.

[MacTavish]

There is serious convection popping up...yet her eye is shrinking..i am so confused.

The eye is being filled with clouds. The actual surface center is displaced to the south of the clear spot you can see on IR

[AutoPenalti]

Levi mentioning that GFS and Euro still having a tough time trying to figure out the shortwave.

[GeneratorPower]

There is serious convection popping up...yet her eye is shrinking..i am so confused.

The eye is still there. Recon verified closed eye at 25 mi diameter. It’s probably covered with more clouds than before. Microwave imagery shows it too. The issue is some sort of quasi ERC and shear from the southwest because of the upper low. I think once the ERC completes, or whatever that is it’s doing, it may round out a little more. Still a monster storm, really. Katrina kinda fell apart on the south side right before landfall. It didn’t matter did it?

[SouthFloridawx]

18Z GFS has the ULL pulling farther away in 12-18 hours, and not affecting it as much.

[tolakram]

870
URNT12 KNHC 122352
VORTEX DATA MESSAGE AL062018
A. 12/23:25:40Z
B. 31.37 deg N 073.09 deg W
C. 700 mb 2706 m
D. EXTRAP 956 mb
E. NA
F. OPEN SE
G. C22
H. 75 kt
I. 201 deg 24 nm 23:19:00Z
J. 278 deg 94 kt
K. 196 deg 20 nm 23:20:00Z
L. 79 kt
M. 037 deg 21 nm 23:33:30Z
N. 131 deg 103 kt
O. 046 deg 56 nm 23:45:00Z
P. 14 C / 3050 m
Q. 18 C / 3045 m
R. 6 C / NA
S. 12345 / 7
T. 0.02 / 3 nm
U. AF308 1306A FLORENCE OB 03
MAX FL WIND 103 KT 046 / 56 NM 23:45:00Z
SLP EXTRAP FROM 700 MB
MAX FL TEMP 20 C 185 / 8 NM FROM FL CNTR
;

[MacTavish]

There is serious convection popping up...yet her eye is shrinking..i am so confused.

The eye is still there. Recon verified closed eye at 25 mi diameter. It’s probably covered with more clouds than before. Microwave imagery shows it too. The issue is some sort of quasi ERC and shear from the southwest because of the upper low. I think once the ERC completes, or whatever that is it’s doing, it may round out a little more. Still a monster storm, really. Katrina kinda fell apart on the south side right before landfall. It didn’t matter did it?

VDM says open eyewall to the SE