2025 Global Model Runs Discussion (Out thru day 16)

[ronjon]

12z Euro forms a weak low in the SW Caribbean but keeps it a weak vortex that migrates to the Yucatan Channel and dissipates.

[MarioProtVI]

The rule of thumb is, don’t expect a December storm because then said storm won’t form at all

That being said I still strongly think this is just a byproduct of South American vorticity bias (which the GFS is notorious for especially late in the season). 700 mb vorticity shows this pretty well, so I’m not sure if the other models showing something are also having the same kind of issue. I don’t expect anything to come out of it really.

[StormWeather]

The AIFS (EURO-AI) model does have a 1005 mb closed low near Cancun by December 4th on the 18Z run. It’s 12 days out so take it with a grain of salt for now.

But the fact that the 18Z run of the EURO-AI model shows this is saying something, considering how well the AI models have performed throughout this year.

The thing I would look for now is consistency and back-to-back runs on the AI models and I will trust this signal more.

[ronjon]

18z GFS has 987 mb storm into La.

[MarioProtVI]

00z GFS makes it 963 mb major before Yucatan on December 3 the proceeds to strike Florida as a transitioning-to-EX Cat 1

[ronjon]

06z GFS into FL big bend as a tropical storm. It's persistent but probably persistently wrong.

[mitchell]

Boy I'll say persistent. 12z GFS now makes 7 runs in a row with essentially the same solution: Tropical system forms in WCAR off Venezuela, moves across Yucatan/Straight into gulf, recurves NE and landfalls between NOLA and Tampa.

[cycloneye]

And now there are two.

[WaveBreaking]

Ok sure thing GFS

[Category5Kaiju]

I know we all like to make fun of it (for good reasons, lol), but does somebody know exactly why the GFS in particular has a proclivity for persistently spinning up vorticity near Panama/Colombia into strong storms, especially during the late May/June timeframes? And, in this case, early December?

[HURRICANELONNY]

It has been doing those runs all year. Doubt anything will happen but GFS hates florida. Get Florida Soon

[Team Ghost]

I know we all like to make fun of it (for good reasons, lol), but does somebody know exactly why the GFS in particular has a proclivity for persistently spinning up vorticity near Panama/Colombia into strong storms, especially during the late May/June timeframes? And, in this case, early December?

The only people who know are the ones who program the GFS.

[Hurricane2022]

18z - GFS shows that TS again.

[ronjon]

There is some minor support from 12z Icon (1008 mb low) and 12z Euro with another weak low in the SW Caribbean. Euro doesn't really do much with it while Icon doesn't run out far enough to know.

[Teban54]

949 mb in December, sure:

[LarryWx]

[list=][/list]

949 mb in December, sure:

https://i.imgur.com/u4kLWn5.gif

Whereas the strength is very hard to imagine, the GFS has little, if any, company, and the GFS often has fake hurricanes in the W basin forming just N of South America, I am considering these things that suggest to me that there being a storm at all in the W basin wouldn’t be too hard to believe:

-There is forecasted by the GFS to at the same time be a TCG conducive anomalously strong upper ridge to its NW (992-3 dm H5 in Gulf) around when the GFS has this form. But is the ridge being that strong right?

-2013 was the last time Dec had any ACE and that was from an unnamed STS. That means it has been 12 years. In the satellite era, the longest Dec droughts had previously been 9 years (twice). So, whereas it being overdue doesn’t make it more likely, that does show that’s it’s not as rare as some may think. From 1998-2007, 6 of those 10 seasons had Dec ACE!