ATL: INVEST 93L - Discussion

[redingtonbeach]

I see that one of the newer NHC forecasters, Lisa Bucci, updated Hagen's outlook and kept development chances at 40%. Perhaps she didn't feel comfortable going higher?

I have never seen anyone on this forum speak about an individual NHC forecaster like that. And what a coincidence that it is the only woman on the team.

Yeah, I didn't dig that either. No sense pointing fingers.

[USTropics]

Satellite imagery and radar clearly show that Invest 93L has a tilted structure with height. Let's begin with radar, which provides a solid depiction of the system's evolution since this morning. Below are the last 200 radar frames from Melbourne, primarily tracking the mid-level circulation (MLC) later in the sequence. These images reveal a clear westward trajectory toward the GOM:


Meanwhile, satellite imagery is still clearly showing our LLC, but we also are starting to see signs this is becoming elongated and stretched out from the NE to SW as it heads more WNW (i.e., opening more into a trough):


CIMSS 850mb vorticity products also corroborates this:


Another way to visualize the tilt is using Earth.null (https://earth.nullschool.net/) and selecting the different layers of the atmosphere. Here I've created an animated gif of the 850mb (low), 700mb (mid), and 500 mb (upper) level vorticity:


Where is this going and what are the chances of sneaking out a name? I do believe this was classifiable earlier today, and that was the first window (which is now closed imo). It seems the 12z HAFS-B and ECMWF have the best grasp on the evolution so far. The evident vorticity and shear was accurately captured here on the HAFS-B:


So let's take kind of a step back and look at what the HAFS-B Parent is fully showing us. We already talked about the tilt with height, and we can see in the 850mb analysis below we still have the semblance of a trough feature again here (highlighted in pink). We see this sort of dipole of vorticity maximums embedded in the trough axis (blue arrows roughly indicating future trajectory), and focusing on the northern vorticity (where our LLC is), this should track through northern Florida/Georgia tonight and remerge in the GOM tomorrow. Meanwhile, our MLC (not featured here but roughly green arrow) will continue westward:


If we play out the full animation here (and this is where models differ), how quickly the vorticity can be reestablished in the GOM will determine if it can develop enough to be classified. If it can scrape along the coast of Louisiana, I think it has a solid chance:


Trend for last 3 ECMWF runs:

[eastcoastFL]

Been pretty breezy all day in Juno Beach but pretty nice out otherwise. Yesterday was a washout. Glad that's over with.

[tropicwatch]

Elongated circulation at the 700mb level.

https://earth.nullschool.net/#current/wind/isobaric/700hPa/orthographic=-81.55,26.68,2184

[Hurricane2022]

Looking quite good right now.

[tropicwatch]

Looks like the surface low has given up the ghost.

Surface
https://earth.nullschool.net/#current/wind/surface/level/orthographic=-81.66,26.51,2184

Elongated 850mb level might consolidate
https://earth.nullschool.net/#current/wind/isobaric/850hPa/orthographic=-81.66,26.51,2184

700mb level similar to the 850mb level
https://earth.nullschool.net/#current/wind/isobaric/700hPa/orthographic=-81.66,26.51,2184

[BobHarlem]

Looking quite good right now.
https://i.imgur.com/iUVlkyy.gif

It's still elongated, but the convection managed to traverse the most narrow part of central Florida somehow. That area near Cedar Key exploded on radar just recently. The tail band on the southeast side is just barely starting to get going. "Centers" appear to be off Cedar Key, near inverness, and the easiest to spot on Jax radar, one west of St. Augustine.

[ScottNAtlanta]

Looks like shear might have eased a bit because the LLC looks to be much nearer the convection than this morning, also...this is a VERY small system. If it holds up until it gets back over water, the models probably will have a hard time with it. It will also need as much distance from the coast if it stays small.

[Stormcenter]

Agree 100%

Looks like shear might have eased a bit because the LLC looks to be much nearer the convection than this morning, also...this is a VERY small system. If it holds up until it gets back over water, the models probably will have a hard time with it. It will also need as much distance from the coast if it stays small.

[Stratton23]

LLC definitely looks like its getting tugged WSW closer to the MLC, though it still has a ways to go, but definitely an improvement in organization compared to what it looked like yesterday

[Javlin]

LLC definitely looks like its getting tugged WSW closer to the MLC, though it still has a ways to go, but definitely an improvement in organization compared to what it looked like yesterday

Definitely see that happening and it's not going to GA but straight into Big Ben area also got a hot tower going close to the LLC

https://www.tropicaltidbits.com/sat/sat ... roduct=vis

[Frank P]

LLC definitely looks like its getting tugged WSW closer to the MLC, though it still has a ways to go, but definitely an improvement in organization compared to what it looked like yesterday

Definitely see that happening and it's not going to GA but straight into Big Ben area also got a hot tower going close to the LLC

https://www.tropicaltidbits.com/sat/sat ... roduct=vis

Yeah, I saw the same thing, if it can get some more wsw motion going for it a TD or named system is possible.

[Stormlover70]

Looks like models trended north. Lots of rain. Seems like it may not develop like previously thought.

[Stratton23]

I dont know about that, given its definitely gotten better organized in terms of convection and pulling the LLC closer to the MLC, models are likely going to be to far north given the motion overall is more WSW now, this is a small system, thats another thing to watch when it gets into the gulf, smaller systems are prone to organize faster than model predictions

[TallyTracker]

I’m a little less enthusiastic about this system’s chances than yesterday. Unless it relocates south or moves wsw, it appears it will skirt the coast of the FL Panhandle to LA. Land interaction may limit development in that case. If it can pull away from land and get the dry air cleared out, I think the chances are good of a weak TS at least. I’m just not confident the circulation is going to move far enough offshore to allow for further development.

[psyclone]

What a forecast fail here locally....a hastily issued flood watch, a 100% chance of rain and not a drop for many areas. Pretty much because our system ended up north of prior estimates... which ultimately bodes poorly for future development prospects.

[Janie2006]

I don’t mind the summer showers and storms. They keep the garden hydrated and the temperature bearable.

What I don’t need is potentially 2-3 days of tropical downpours here in coastal Alabama. Regardless of classification, some folks along the north-central Gulf coast are going to get slammed with rain. Maybe a lot of us.

And of course there will inevitably be the fools who think it’s a good idea to surf some waves.

[cycloneye]

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 PM EDT Tue Jul 15 2025

For the North Atlantic...Caribbean Sea and the Gulf of America:

1. Northeastern and north-central Gulf (AL93):
Satellite and radar data indicate that the low pressure area moving
across the northern Florida peninsula continues to produce
disorganized shower and thunderstorm activity, mainly to the south
and southwest of its center. The system is forecast to move
westward, and it could emerge over the far northeastern and
north-central Gulf, possibly approaching the coast of Louisiana on
Thursday. Environmental conditions over the Gulf appear generally
favorable for additional development, and a tropical depression
could form if the system moves far enough offshore over the next
couple of days.

Regardless of development, heavy rainfall could produce localized
flash flooding over portions of Florida through Wednesday. Heavy
rainfall could also cause flash flooding for portions of the
north-central Gulf Coast beginning late Wednesday and continuing
through Friday. For additional information, please refer to products
issued by your local National Weather Service office.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...medium...40 percent.



Forecaster Hagen

[Hurricane2022]

After seeing the last frames, I think this may not even reach water again at all, unless the MLC tries to really speed up the process of pulling the LLC south or creating a new one now, as it looks like the system is racing straight towards the CONUS.

[BobHarlem]

Last visibles of the day...

Evening storms are confusing the situation agian, MLC seems to be near or in the Gulf now. There's that one ll circulation almost at the FL/GA border, and another perhaps closer to the MLC, and way off on it's own-- a little circulation west of the Keys...