ATL: DEBBY - Post-Tropical - Discussion

[BobHarlem]

This afternoon's radar should help with determining where PTC 4 is consolidating.

Here is the link to Cuba's radars. Fortunately it seems like the ones we need are functional.

http://www.insmet.cu/asp/genesis.asp?TB ... B1=RADARES

Composite here may be a little better
https://www.barbadosweather.org/Composi ... 700&MAPP=1

[StPeteMike]

With satellite showing consolidation of the future Debby in the Gulf of Guacanayabo and the potential of more time over open waters than anticipated, I wouldn’t rule out Hurricane before Florida landfall.

PTC 4 will also be over waters in the Caribbean around 87 to 88 F in that area, with some areas south of the Northern tip of Cuba running close to 90.

[Tailgater33]

My latest estimate where I think the main vorticity is located.

 https://x.com/NDGMETCHEF/status/1819415409059152185

Yep that where I see it as well. probably won’t make much difference in the longer term track ( stronger system feeling the weakness more)

[Poonwalker]

This afternoon's radar should help with determining where PTC 4 is consolidating.

Here is the link to Cuba's radars. Fortunately it seems like the ones we need are functional.

http://www.insmet.cu/asp/genesis.asp?TB ... B1=RADARES

Composite here may be a little better
https://www.barbadosweather.org/Composi ... 700&MAPP=1

This looks farther south than they have it. looks like its near Pilon possibly even over water there

[chaser1]

Well if that comes to fruition it would be quite the game changer for sure!

NHC 3 day cone is pretty lethal. Nothing is impossible though.

Ignore the cone - it has nothing to do with current track uncertainty or impacts. It's quite meaningless, really.

I concur that the cone does not imply impact conditions. I also concur that a 2 or 7 day invest cone is only meant to imply where development could occur (and not where a disturbance is forecast to track). However, are you suggesting that the PTC cone up now at the NHC site (depicting Sat. 8:00pm forecast location of a T.S. at around 25N & 82.5W) is different from their forecast track cone that typically applies to named storms? Margin of error notwithstanding, my understanding was that this was in fact a "forecast track" (and aware that a wide range of impact conditions may extend a significant distance from the center).

[GCANE]

Someone has to be right:
NHC?
CIMSS?
Models?

[Nimbus]

Here is the link to Cuba's radars. Fortunately it seems like the ones we need are functional.

http://www.insmet.cu/asp/genesis.asp?TB ... B1=RADARES

Composite here may be a little better
https://www.barbadosweather.org/Composi ... 700&MAPP=1

This looks farther south than they have it. looks like its near Pilon possibly even over water there

There is a heavy thunderstorm burst west of Pico Turquino where the Cuban mountain range is providing some shear lift. Satellite visible loop does show a potential low level center forming over water south of Cuba if that isn't just an illusion from the shear. NHC 11 AM forecast already has 65 MPH winds in the Tampa bay area.

[chaser1]

My latest estimate where I think the main vorticity is located.

 https://x.com/NDGMETCHEF/status/1819415409059152185

Yep that where I see it as well. probably won’t make much difference in the longer term track ( stronger system feeling the weakness more)

I kind of agree. You're right how a stronger storm is definitely apt to feel a weakness and react to the veering southerly/southwesterly flow caused by the weakness (and orientation of the eroded ridging caused by said weakness). This affect especially applies to small core systems however larger envelope circulations (broadly) tend to react slower and less sharply to at least more subtle steering pattern changes.

[wxman57]

NHC 3 day cone is pretty lethal. Nothing is impossible though.

Ignore the cone - it has nothing to do with current track uncertainty or impacts. It's quite meaningless, really.

I concur that the cone does not imply impact conditions. I also concur that a 2 or 7 day invest cone is only meant to imply where development could occur (and not where a disturbance is forecast to track). However, are you suggesting that the PTC cone up now at the NHC site (depicting Sat. 8:00pm forecast location of a T.S. at around 25N & 82.5W) is different from their forecast track cone that typically applies to named storms? Margin of error notwithstanding, my understanding was that this was in fact a "forecast track" (and aware that a wide range of impact conditions may extend a significant distance from the center).

The cone on NHC's graphics depicts only an average 5-year center error. It says 66.7% of the time, the center tracked within their displayed cone. However, track uncertainty does not necessarily match any 5-yr average. Sometimes there is greater certainty, sometimes less. They really need to come up with more of a probabilistic cone based on current guidance and uncertainty and not use the same exact cone for every storm and every advisory all year long.

[wxman57]

By the way, here's a great website with a satellite loop that displays the latest NHC track. You can determine if the system is following the track. Lots of convection north of the track. My general rule is that the center will follow the convection, never the other way around.

https://zoom.earth/storms/04l-2024/

[BrianS]

Someone has to be right:
NHC?
CIMSS?
Models?

Personally, I would go with the NHC As far as I can deduce, they have been spot on in 2024 so far given the challenging set-up and frequent anomalies thus far.
Go Storm2k!

[StPeteMike]

Wxman, are you saying you don’t believe this storm is going to form with the southern convection and PTC 4 center will be either N or along the northern coast of Cuba?

[wzrgirl1]

Someone has to be right:
NHC?
CIMSS?
Models?

Debby and God.

[DunedinDave]

It is swirling over Cuba. Will be interesting to see if the swirl can get south of Cuba and find some water which would be south of NHC track. If it takes the long way over Cuba like the NHc says, it simply cant strengthen until it gets just south of the Keys.

[SFLcane]

By the way, here's a great website with a satellite loop that displays the latest NHC track. You can determine if the system is following the track. Lots of convection north of the track. My general rule is that the center will follow the convection, never the other way around.

https://zoom.earth/storms/04l-2024/

So you said your expecting the NHC to nudge more east you think it move into SW Florida? If the center does jump north of cuba we could be looking at more impacts potentially across the southern half of the peninsula.

[chaser1]

Ignore the cone - it has nothing to do with current track uncertainty or impacts. It's quite meaningless, really.

I concur that the cone does not imply impact conditions. I also concur that a 2 or 7 day invest cone is only meant to imply where development could occur (and not where a disturbance is forecast to track). However, are you suggesting that the PTC cone up now at the NHC site (depicting Sat. 8:00pm forecast location of a T.S. at around 25N & 82.5W) is different from their forecast track cone that typically applies to named storms? Margin of error notwithstanding, my understanding was that this was in fact a "forecast track" (and aware that a wide range of impact conditions may extend a significant distance from the center).

The cone on NHC's graphics depicts only an average 5-year center error. It says 66.7% of the time, the center tracked within their displayed cone. However, track uncertainty does not necessarily match any 5-yr average. Sometimes there is greater certainty, sometimes less. They really need to come up with more of a probabilistic cone based on current guidance and uncertainty and not use the same exact cone for every storm and every advisory all year long.

That's interesting stuff and did not know it was Soley based on a 5 year average. I certainly thought their 3 day forecast accuracy was far greater than 66.7%, I always have perceived their forecast track forecasts fairly rock solid

[ColdMiser123]

By the way, here's a great website with a satellite loop that displays the latest NHC track. You can determine if the system is following the track. Lots of convection north of the track. My general rule is that the center will follow the convection, never the other way around.

https://zoom.earth/storms/04l-2024/

Depends on what type of convection.

The convection south of Cuba looks to be updraft driven, while the convection well north of Cuba looks to be cold pool driven (i.e. the deepest convection is on the edges of the northern cloud canopy).

[chaser1]

Someone has to be right:
NHC?
CIMSS?
Models?

Debby and God.

Maybe throw in, "our eyes" too

[GCANE]

19.1N 77.7W
Looks like some low-level clouds moving west to east

[skillz305]

Waiting for the 2pm advisory update