Possible development in the Western Atlantic / GOM (Is Invest 97L)

[BobHarlem]

Sure, go for hurricane Debby




And cat 2...

landfalls in the panhandle after this, but still is crawling, going for Alabama still raining, finally starts really moving again deeper inland about midday Friday.

[chaser1]

One thing I recently noticed with this setup is that models were possibly overdoing the Fujiwhara interaction between the ITCZ disturbance and the AEW.

Current satellite imagery shows our main wave axis near the Leeward Islands, but the ITCZ disturbance is lagging behind and is elongated E to W.
https://i.imgur.com/kJ7YDbG.jpeg

My original understanding of what supposed to happen between the two vort maxes was that the ITCZ disturbance was supposed to pivot N of the wave, strengthen, and become the dominant feature as seen below:
https://i.imgur.com/aO1dych.gif

But what happened instead was that the ITCZ disturbance failed to pivot N into more favorable conditions and instead got sheared out by the wave, meaning that the wave was never pulled N.
https://i.imgur.com/GtbKYmb.jpeg

Therefore, one could make the conclusion that the more southern track solutions are more likely barring any downstream influence from a stronger-than-forecast trough.

The original set up actually had an ITCZ disturbance AHEAD and southwest of the large and dry mid level low that we are now tracking. The assumption was that the larger (higher latitude) mid level low would catch up to, and pull that ITCZ vorticity up and into its broader circulation. More than any Fujiwhara affect, the diminutive lower latitude disturbance essentially got sheared by the fast approaching low now spreading over the Leewards and Puerto Rico

[LarryWx]

12Z UKMET: way west (TCG 150 miles S of LA tip and moves NNW into LA) and pretty weak:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 120 HOURS
FORECAST POSITION AT T+120 : 27.0N 89.3W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 05.08.2024 120 27.0N 89.3W 1011 31
0000UTC 06.08.2024 132 28.6N 90.2W 1009 29
1200UTC 06.08.2024 144 30.0N 90.5W 1011 30
0000UTC 07.08.2024 156 30.8N 91.0W 1009 27
1200UTC 07.08.2024 168 31.5N 90.7W 1010 28

[cycloneye]

I wish they'd make it an invest so it can have a floater. I keep going into Tropical Tidbits forgetting that there's no floater yet and have to settle for one of the wider views instead.

I am refreshing the site for invests. as it can come at any time. In the meantime, I would like Levi to put a Meso floater on the wave.

https://ftp.nhc.noaa.gov/atcf/btk/

[toad strangler]

12z CMC into Tampa and then NE stalling in GA/SC. Yikes

[GCANE]

Looking at CIMSS
925 & 700mb vort are just east of PR
500mb vort is farther to the east,

GFS doesn't initialize it very well, showing wave-type structures.
The 500mb vort will likely make it thru the Antilles and enter the GoM NW of Cuba.

It would be very likely strong convection would drive the Mid-Level vort to the surface.
That's what Hot Towers are noted for.
This could lead to a significant TC in the GoM.

[BobHarlem]

12z CMC goes over the keys, inthe Gulf briefly, then into Tampa Bay, then stalls out over Southeast Georgia near Brunswick for the rest of the run. Slight left shift from 0z (0z didn't stall either).

[SFLcane]

[wxman57]

GFS remains the only model that predicts a closed low center in the Gulf. It's 12z run looks quite odd. Let's hope something like that doesn't materialize. I'm still thinking east of Florida is more likely.

[tropicwatch]

Along with the convection, the vorticity appears to no longer be elongated and becoming more concentric.

[Teban54]

Funny enough, the forecast uncertainty and divergence from soon-to-be Debby 2024 is reminiscent of Debby 2012. At one point, even the NHC forecast had it moving towards Texas from the middle of the GoM, but it eventually landfalled in Florida instead.

I didn't track the storm myself, but I recall from other comments that there was also a GFS vs. Euro situation involved?

Not saying anything about Debby 2012 was applicable to Debby 2024 (they probably aren't), just an interesting observation.

[BobHarlem]

GFS Rainfall estimates for that run, for the record.

[SFLcane]

[SFLcane]

GFS remains the only model that predicts a closed low center in the Gulf. It's 12z run looks quite odd. Let's hope something like that doesn't materialize. I'm still thinking east of Florida is more likely.

Only model? Hmm Icon, cmc, ukmet, and throw in the gefs ensembles as of 12z.

[chaser1]

Like ALWAYS, timing is everything. 6-12 hr's of difference might give you more of an ICON solution OR a GFS solution. My problem with the ICON is that it seems to ignore the influence of the rising heights to its north. My problem with the GFS is, nobody wants another Elena (or 2/3's of Florida, S Georgia and Alabama) to receive 8+ inches of rain and 4 days of coastal hurricane conditions. This is 2024 though.....

I smell an NHC southward and westward shift to their "development cone" by this evening, especially if EURO or its ensembles continue to shift west or signals for development suggest weaker overall.

[Ubuntwo]

One thing I recently noticed with this setup is that models were possibly overdoing the Fujiwhara interaction between the ITCZ disturbance and the AEW.

Current satellite imagery shows our main wave axis near the Leeward Islands, but the ITCZ disturbance is lagging behind and is elongated E to W.
https://i.imgur.com/kJ7YDbG.jpeg

My original understanding of what supposed to happen between the two vort maxes was that the ITCZ disturbance was supposed to pivot N of the wave, strengthen, and become the dominant feature as seen below:
https://i.imgur.com/aO1dych.gif

But what happened instead was that the ITCZ disturbance failed to pivot N into more favorable conditions and instead got sheared out by the wave, meaning that the wave was never pulled N.
https://i.imgur.com/GtbKYmb.jpeg

Therefore, one could make the conclusion that the more southern track solutions are more likely barring any downstream influence from a stronger-than-forecast trough.

This is great analysis. I noticed that evolution on the GFS at the start of this thread, it was all alone at that time.

Here’s another call the GFS looks to have pinned. The upper-level trough at roughly 30N 58W was expected by most models to lift, allowing outflow north of the greater Antilles permitting a quicker spinup and likely path OTS. The GFS defied consensus by having this trough dip south & cutoff into a low, limiting favorable conditions to over and south of the Greater Antilles. Based on satellite analysis, the later solution has panned out. This lends credence to a track further south.

[GCANE]

Looking at CIMSS
925 & 700mb vort are just east of PR
500mb vort is farther to the east,

GFS doesn't initialize it very well, showing wave-type structures.
The 500mb vort will likely make it thru the Antilles and enter the GoM NW of Cuba.

It would be very likely strong convection would drive the Mid-Level vort to the surface.
That's what Hot Towers are noted for.
This could lead to a significant TC in the GoM.

GFS has a strong anti-cyclone developing in the east GoM a day later when this mid-level vort exits Cuba

[3090]

GFS remains the only model that predicts a closed low center in the Gulf. It's 12z run looks quite odd. Let's hope something like that doesn't materialize. I'm still thinking east of Florida is more likely.

Models are trending west. But I hope your “Let’s hope something like that doesn’t materialize” thinking. We shall see.

[chaser1]

Looking at CIMSS
925 & 700mb vort are just east of PR
500mb vort is farther to the east,

GFS doesn't initialize it very well, showing wave-type structures.
The 500mb vort will likely make it thru the Antilles and enter the GoM NW of Cuba.

It would be very likely strong convection would drive the Mid-Level vort to the surface.
That's what Hot Towers are noted for.
This could lead to a significant TC in the GoM.

GFS has a strong anti-cyclone developing in the east GoM a day later when this mid-level vort exits Cuba

Could be bad juju on the horizon Going forward from here, I would definitely say slower is bad/faster-better

[Frank P]

https://i.postimg.cc/T2kHr28m/bnbnb.gif

looking at the sat loops I can image this thing possibly splitting the energy, it's quite elongated with convection building on the northern part of the wave as well as the southern section below Puerto Rico...will be interesting to see how it all plays out..