ATL: FLORENCE - Post-Tropical - Discussion

[1900hurricane]

Pressure appears to be dropping in this pass. No stronger winds found, however.

Isn't their typically a lag between pressure drops and winds picking up?

It depends on structure. In the case of a system trying to establish a core or having core issues this is pretty common. However, with a rapidly intensifying system with a well established core, it sometimes works the opposite way. Florence definitely fits the first case.

[Ken711]

11 AM NHC Discussion:

The satellite and radar presentations of Florence have improved
somewhat this morning, with a 20-25 nmi wide eye closing off in the
radar data from the Morehead City and Wilmington WSR-88D Doppler
weather radars. However, an Air Force Reserve reconnaissance
aircraft investigating the hurricane this morning has not yet found
any flight-level or SFMR winds to support more than about 80 kt at
the surface thus far, even though the pressure has decreased to 955
mb. The initial intensity has only been lowered to 90 kt, given
that there are peak Doppler velocity values up to 110 kt with
average values of 95-97 kt at 15,000 ft in the northern eyewall
region, an area of the hurricane that the reconnaissance aircraft
has not yet sampled. The upper-level outflow pattern remains quite
impressive.

Florence has been gradually slowing down this morning, and the
initial motion estimate is now 315/09 kt. The subtropical ridge to
the northeast and east of Florence is now well-established between
Bermuda and the U.S. mid-Atlantic region and extends westward into
Virginia and the central Appalachians. This large-scale feature is
expected to keep the hurricane moving northwestward today, followed
by a turn toward the west at a much slower speed on Friday as the
ridge to the north of Florence weakens due to a weak shortwave
trough dropping slowly southward from the Ohio Valley. On days 3-5,
Florence is forecast turn toward the northwest and north around the
western periphery of the subtropical ridge, and move across western
South Carolina on Sunday, across western North Carolina and eastern
Tennessee on Monday, and then move up the spine of the Appalachians
as an extratropical low after the cyclone merges or interacts with a
frontal system. The new NHC forecast track is similar to the
previous one, and lies close to a blend of the consensus models
TVCA, HCCA, and FSSE.

Florence is currently approaching the Gulfstream current, and the
hurricane is forecast to move over warmer and deeper waters in 6-12
hours, which could allow for some slight strengthening. Just prior
to landfall in about 24 hours, Florence is expected to weaken some
due to upwelling of the shallow coastal waters. After landfall
occurs, rapid weaning of the stronger inner-core wind field is
expected to due land interaction and Florence's slow forward speed
of 5 kt or less. However, intense rainbands are expected to develop
over the Atlantic waters and keep moving along the coast and inland,
likely producing strong wind gusts through Saturday night.

[artist]

Experts here, do I recall correctly that if pressure drops, but winds aren’t it could be the wind field increases?

[Steve]

https://weather.cod.edu/satrad/nexrad/index.php?type=MHX-N0Q-1-48
Back up again...

Closing up the dry slot to the NW and the eyewall on the radar appears to be intensifying.

It does. But there's a pretty significant dry slot around the closed off center to the SW/S/SE/E/NE/N. I hate conspiracy theories and their believers, but the magnitude of that dry slot is suspect. May or may not be natural causes.

Ok... I need you to elaborate. What beyond natural causes would be causing dry slots?

If you switch out to visible or actually to the IR non-enhanced, it's really just shear coming up and feeding into the south of the system. It's lopsided to the north like you sometimes see in northern latitude systems, and it's feeding in and wrapping around. I think that Florence will be able to work that out, but it is a significant disrupter. I actually didn't think they were dropping dy-no-mat into it. It was just that it looked suspect on radar.

Also, significant uptick on the frying pan cam on that rig and also a slight change in wind direction.
https://youtu.be/deG4NxkouGM

[SoupBone]

https://twitter.com/jeffhampton56/status/1040242850787717120

That is insane, and it hasn't really even begun.

[wx98]

Pressure appears to be dropping in this pass. No stronger winds found, however.

Isn't their typically a lag between pressure drops and winds picking up?

It looks to me like more of a Sandy scenario where the pressure it low but the wind field is so spread out that there is not a correlating increase in wind speeds.

[sikkar]

Escalating really quick at the Frying Pan .

[Nasdaq]

Brett Adair LIVE https://livestormchasing.com/stream/brett.adair

[wx98]

https://weather.cod.edu/satrad/nexrad/index.php?type=MHX-N0Q-1-48
Back up again...

Closing up the dry slot to the NW and the eyewall on the radar appears to be intensifying.

It does. But there's a pretty significant dry slot around the closed off center to the SW/S/SE/E/NE/N. I hate conspiracy theories and their believers, but the magnitude of that dry slot is suspect. May or may not be natural causes.

Huh? Definitely more likely a result of shear and land interaction than anything else.

[sicktght311]

Pressure appears to be dropping in this pass. No stronger winds found, however.

Isn't their typically a lag between pressure drops and winds picking up?

It looks to me like more of a Sandy scenario where the pressure it low but the wind field is so spread out that there is not a correlating increase in wind speeds.

Yeah Sandy caught a lot of people by surprise. Wind gusts barely registered over 100mph, but the damage, as everyone knows, was extensive from the catastrophic surge. Cat 1 wind speeds, but Cat 3 or higher surge

[Ken711]

 https://twitter.com/JackSillin/status/1040250893592092673

[marionstorm]

Looks like wnw motion may have begun

[meriland29]

Do you think there is even a chance she will get stronger instead of using the energy to widen her size?

[Slughitter3]

First tornado warning. Sadly I'm sure it's one of many. Be safe everyone

Sent from my SM-G960U using Tapatalk

[jasons2k]

It does. But there's a pretty significant dry slot around the closed off center to the SW/S/SE/E/NE/N. I hate conspiracy theories and their believers, but the magnitude of that dry slot is suspect. May or may not be natural causes.

Ok... I need you to elaborate. What beyond natural causes would be causing dry slots?

If you switch out to visible or actually to the IR non-enhanced, it's really just shear coming up and feeding into the south of the system. It's lopsided to the north like you sometimes see in northern latitude systems, and it's feeding in and wrapping around. I think that Florence will be able to work that out, but it is a significant disrupter. I actually didn't think they were dropping dy-no-mat into it. It was just that it looked suspect on radar.

Also, significant uptick on the frying pan cam on that rig and also a slight change in wind direction.
https://youtu.be/deG4NxkouGM

The flat look is because it's bumping into the ridge....

[ScottNAtlanta]

Recons next set of data will be through the center

[GCANE]

Looks like Flo is hitting the brakes hard.

[Steve]

https://weather.cod.edu/satrad/nexrad/index.php?type=MHX-N0Q-1-48
Back up again...

Closing up the dry slot to the NW and the eyewall on the radar appears to be intensifying.

It does. But there's a pretty significant dry slot around the closed off center to the SW/S/SE/E/NE/N. I hate conspiracy theories and their believers, but the magnitude of that dry slot is suspect. May or may not be natural causes.

Huh? Definitely more likely a result of shear and land interaction than anything else.

It is.

But it looked odd where it was coming from on radar. You can see it clearly on Satellite. It's a dry air wedge working its way through the system. It will probably happen a couple more times based on the drier air to the south.

[artist]

Local officials, if you refuse to leave, have up to two weeks of water, food, etc.

[Steve]

Ok... I need you to elaborate. What beyond natural causes would be causing dry slots?

If you switch out to visible or actually to the IR non-enhanced, it's really just shear coming up and feeding into the south of the system. It's lopsided to the north like you sometimes see in northern latitude systems, and it's feeding in and wrapping around. I think that Florence will be able to work that out, but it is a significant disrupter. I actually didn't think they were dropping dy-no-mat into it. It was just that it looked suspect on radar.

Also, significant uptick on the frying pan cam on that rig and also a slight change in wind direction.
https://youtu.be/deG4NxkouGM

The flat look is because it's bumping into the ridge....

That's what happens when they do. But it shows more in the northern latitudes where you have that phenomena more than in the deeper tropics.