2024 Global Model Runs Discussion (Out thru day 16)

[Teban54]

As others said, 12z GEFS seems similarly active to 0z and 6z. At 162 hrs, I count about 17 members (55%) with a low in the central Atlantic from this wave, most of which appeared in the Day 4-5 range. You can compare that to the 0z and 6z counts here. 12z also shows a pronounced S shift in track.

(Edit: Revised the number to 17, but it can also be as low as 15 as two other lows may be from a subsequent wave. Also, just for fun, one of the ensemble members show Beryl 2.0. This is the furthest south I've seen in a reasonably close-in time frame.)



12z GFS has 4 AOIs:

1. A weak vort during 72-96 hrs in the central Atlantic, that dissipates soon after. I believe it's the same wave that its ensembles are showing.

2. A TS just offshore Africa in 8 days (9/3). This has one of the wildest evolutions I've seen: Develops quickly after splashdown and gets down to 1005 mb, only to do a Fujiwhara with another wave inside Africa and gets pulled southeast. The system (or its remnants) even make landfall in Africa, before moving N near the coastline and NW again. I can't recall many storms moving SE, and certainly not this far east!



3. A weak vort/TC in the central Atlantic starting at around 276 hrs, ending the run NE of the Lesser Antilles.

4. A Gulf hurricane from the same wave as #1. Usual caveats that GFS's South American vorticity may be involved.

[Hurricaneman]

My thoughts here with the models is if something really dangerous happens and the models are slow with the uptick, a year one has to remember on this one is 2019 when it showed cat 5 Dorian as a diffuse low or depression at best so just because the op runs are showing little to nothing doesn’t mean a dangerous hurricane isn’t on the horizon

The ensembles are a better way to show conditions in the longer ranges than the op runs which seem to have development biases especially when there’s an uptick

[TomballEd]

I think the Gulf system shown on the GFS is from the systems ensembles are showing approaching the Caribbean Day 10, tracking the moisture envelope. I don't think this is one of the SW Caribbean spinups the GFS likes from phantom vortices that comes off South America.

I am NOT saying it will develop, but it isn't a pure phantom cane, either.

[AutoPenalti]

As others said, 12z GEFS seems similarly active to 0z and 6z. At 162 hrs, I count about 17-18 members (55-59%) with a low in the central Atlantic from this wave, most of which appeared in the Day 4-5 range. You can compare that to the 0z and 6z counts here. 12z also shows a pronounced S shift in track.

https://i.postimg.cc/6QpkqH7w/image.png

12z GFS has 4 AOIs:

1. A weak vort during 72-96 hrs in the central Atlantic, that dissipates soon after. I believe it's the same wave that its ensembles are showing.

2. A TS just offshore Africa in 8 days (9/3). This has one of the wildest evolutions I've seen: Develops quickly after splashdown and gets down to 1005 mb, only to do a Fujiwhara with another wave inside Africa and gets pulled southeast. The system (or its remnants) even make landfall in Africa, before moving N near the coastline and NW again. I can't recall many storms moving SE, and certainly not this far east!

https://i.postimg.cc/28YX3HJJ/gfs-z850-vort-atl-fh150-318.gif

3. A weak vort/TC in the central Atlantic starting at around 276 hrs, ending the run NE of the Lesser Antilles.

4. A Gulf hurricane from the same wave as #1. Usual caveats that GFS's South American vorticity may be involved.

AOI #2 seems to be just a known issue with the GFS and it's convective feedback. I don't think this will appear by 18z.

[cheezyWXguy]

As others said, 12z GEFS seems similarly active to 0z and 6z. At 162 hrs, I count about 17-18 members (55-59%) with a low in the central Atlantic from this wave, most of which appeared in the Day 4-5 range. You can compare that to the 0z and 6z counts here. 12z also shows a pronounced S shift in track.

https://i.postimg.cc/6QpkqH7w/image.png

12z GFS has 4 AOIs:

1. A weak vort during 72-96 hrs in the central Atlantic, that dissipates soon after. I believe it's the same wave that its ensembles are showing.

2. A TS just offshore Africa in 8 days (9/3). This has one of the wildest evolutions I've seen: Develops quickly after splashdown and gets down to 1005 mb, only to do a Fujiwhara with another wave inside Africa and gets pulled southeast. The system (or its remnants) even make landfall in Africa, before moving N near the coastline and NW again. I can't recall many storms moving SE, and certainly not this far east!

https://i.postimg.cc/28YX3HJJ/gfs-z850-vort-atl-fh150-318.gif

3. A weak vort/TC in the central Atlantic starting at around 276 hrs, ending the run NE of the Lesser Antilles.

4. A Gulf hurricane from the same wave as #1. Usual caveats that GFS's South American vorticity may be involved.

Regarding number 4, as soon as I saw the L pop up in the gulf in the long range I went to the vorticity maps to see if it was the usual fluke. To be honest, this is the first run I’ve seen where the signature looks to cleanly originate from the central Atlantic wave, and not spurious gyre activity.

[wxman57]

I was talking to a good friend of mine who use to work for the NHC over 15 years ago, and we both agreed that forecasting a certain amount of storms is dumb. I really wish they would stop doing it. It's much better just to say that it will be an average, or below average or above average year. Trying to predict the exact amount of storms like they do is like those who try and predict the stock market over the next year. Predicting an exact number of storms doesn't make sense, as it's pretty much unpredictable, just as we are seeing this year. Way too many variables.

I completely agree that a seasonal forecast is not something that anyone can take any actions on. You have to prepare the same no matter how many storms or how active a season is predicted. I'd just as soon stop making such predictions unless skill can be shown in predicting what areas would be a higher risk of an impact. Insurance companies would like that kind of information. Unfortunately, there is just about zero skill in that area. However, the general public (and our clients) love to hear presentations on what kind of a season we're expecting each spring. It gives them something to discuss in their pre-season meetings.

[Weathertracker96]

12z gfs looks like it actually develops the wave with ensemble support. The catch is, it doesn’t develop it until 336hr when it’s approaching the southern gulf. It also briefly develops a system near Cabo Verde and a third in the central Atlantic, all pretty weak through 336hr though.

12z gefs starts to pick up on the signal for the first wave around hour 114, fairly strong signature a day or so later

Also, the 12Z CMC has a weak reflection of this same AEW at the surface (stronger than 0Z run) that moves WNW to S Bahamas at 240. Could be a warning of sorts. I think a bear watch may need to be issued soon.

Thanks for pointing it out. I took it as this could be showing how steering may be in the near future. Definitely one to watch since conditions could allow for formation.

[TomballEd]

The Gulf system from the GFS seems more likely than not, based on other models and ensembles. Now, based on the models, a track through the Caribbean into the Gulf is no more likely than a track N of the Caribbean.


A Gulf system before that is possible looking at Canadian and GFS ensembles. Closer in time, but I'm not sure what the models are developing.

I'd Giphy, but all the good websites are blocked at work

[LarryWx]

I am not sure how to post images but the 12z Icon on pivotal weather is showing activity.

You can upload the image to Imgur and copy and paste the BBCode link from the “Get Share Links” button to post an image btw.

12z ICON
https://i.imgur.com/K9eQbWl.gif

For the record, ICON has had a sfc low with this on every 0Z/12Z run since way back at the 12Z of 8/23!

[SFLcane]

12z Euro has a strong TS south of PR..

[LarryWx]

As others said, 12z GEFS seems similarly active to 0z and 6z. At 162 hrs, I count about 17 members (55%) with a low in the central Atlantic from this wave, most of which appeared in the Day 4-5 range. You can compare that to the 0z and 6z counts here. 12z also shows a pronounced S shift in track.

(Edit: Revised the number to 17, but it can also be as low as 15 as two other lows may be from a subsequent wave. Also, just for fun, one of the ensemble members show Beryl 2.0. This is the furthest south I've seen in a reasonably close-in time frame.)

https://i.postimg.cc/6QpkqH7w/image.png

I’m glad you pointed this out in your edit. I see 3 of the members with a TS+ that originate from a followup AEW not coming off Africa til Wednesday.

[TomballEd]

12z Euro has a strong TS south of PR..

Lunch break. Do you have an image of 500 mb of that TS? I can't see Euro before my lunch ends.

[SFLcane]

[DorkyMcDorkface]

12z Euro has a strong TS south of PR..

[SFLcane]

12z Euro has a strong TS south of PR..

Lunch break. Do you have an image of 500 mb of that TS? I can't see Euro before my lunch ends.

Can't share those but it looks like about a 50kt TS mostly heading westward @240hrs similar to the GEFS which has some big ones close to PR.

[aspen]

The operational GFS is still struggling to produce anything. Every time a wave tries to get together on the model, it fizzles out. The GFS is known for having a hard time responding to changing patterns like the MJO, so it’s hard to tell if it’s right in saying the current dry air/AEJ problems will persist in the next 1-2 weeks, or if it’s failing to recognize that the pattern may be changing (different MJO phase, breakdown of the hyper-monsoon trough) as we get into September.

[AnnularCane]

Looks like support is growing for at least one tropical development in the area bounded by 10 N 60 W and 10 N and 20 W. That's a wall of ensemble members showing something going on. We should have something to track here within the next week I would imagine. ITCZ has shifted south to 10 N now and things are changing out there quickly.

https://www.tropicaltidbits.com/analysis/models/gfs-ens/2024082612/gfs-ememb_lowlocs_atl_28.png

Where on TT do you go to look at those Spaghetti-O models? Or the regular spaghetti ones? Apparently it's not simply a matter of clicking on Ensembles.

(I like to use the scientific terms. )

[TomballEd]

:double:

https://i.postimg.cc/HsnjRyBH/nnn.png

Unlike a few days ago, these systems aren't staying just over 10 days away. These ensemble members, unlike a few days ago, don't seem to be a mirage. I think we'll see a model based lemon for the 7 day outlook by Wednesday or Thursday of this week for the MDR system the models/ensembles are seeing a week away., and I suspect development odds will increase. I wouldn't be shocked, if ECENS are similar, for the 7 day lemon to start tomorrow.

[WaveBreaking]

12z Euro has a strong TS south of PR..

Lunch break. Do you have an image of 500 mb of that TS? I can't see Euro before my lunch ends.

[cycloneye]

 https://x.com/AndyHazelton/status/1828135529835073848