2025 Global Model Runs Discussion (Out thru day 16)

[Stratton23]

I don’t think it stays quiet behind ERIN, a kelvin wave will be moving across the basin which should help to boost the waves behind ERIN, doesnt look insanely busy, but definitely not dead quiet either

[convergencezone2]

There be a 98L/Fernand after Erin, which will also almost immediately recurve. Might be another after that. Maybe.

After that, anything would probably be 'home brew'. I see the random systems closer to the US but ensembles usually manage to get a random storm forecast Famous last words but I think the tropics will be quiet the next two weeks

Hoping we do get major hurricane satellite imagery from Erin and any possible MDR storm that may follow in its foot steps.

Even if every single one of these storms coming off Africa does recurve due to weak high pressure, I think we will still get a couple of storms by the end of September / October that will develop in either the Gulf or the Carib that will pose an actual landfall threat.

[TomballEd]

There be a 98L/Fernand after Erin, which will also almost immediately recurve. Might be another after that. Maybe.

After that, anything would probably be 'home brew'. I see the random systems closer to the US but ensembles usually manage to get a random storm forecast Famous last words but I think the tropics will be quiet the next two weeks

Hoping we do get major hurricane satellite imagery from Erin and any possible MDR storm that may follow in its foot steps.

Even if every single one of these storms coming off Africa does recurve due to weak high pressure, I think we will still get a couple of storms by the end of September / October that will develop in either the Gulf or the Carib that will pose an actual landfall threat.

I don't doubt that. Late season storms affecting Florida seems to have become very common.

[WeatherBoy2000]

The euro weeklies is showing well above normal ace in the short term (largely due to Erin), however, this is predicted to quickly fall off. The first half of September is predicted to be below normal, this is likely due to the mjo becoming unfavorable for the basin by then.

[LarryWx]

The euro weeklies is showing well above normal ace in the short term (largely due to Erin), however, this is predicted to quickly fall off. The first half of September is predicted to be below normal, this is likely due to the mjo becoming unfavorable for the basin by then.

Indeed, the latest Euro Weeklies are showing only 80% of ACE for 9/1-14, a big drop from the progged 400% for 8/18-24 due to Erin to ~1/2 the progged ACE for 8/18-24 (likely MJO related as you said).

But then again, it’s 80% of the very active 2005-24 climo for near peak season. So, even if the 80% were to verify well, that would still mean an active period (even though not to the degree of the Erin week) and would end up way more active than for that period in 2024. Sep 1-14 of 2024 had only ~5-6 ACE, which is a mere <20% of the ~31 ACE avg for 2005-24. Compare that to the EW’s 80% prog, which would be ~25 ACE for Sep 1-14 of 2025 or 4-5 times as high as 2024.

[WeatherBoy2000]

The euro weeklies is showing well above normal ace in the short term (largely due to Erin), however, this is predicted to quickly fall off. The first half of September is predicted to be below normal, this is likely due to the mjo becoming unfavorable for the basin by then.

Indeed, the latest Euro Weeklies are showing only 80% of ACE for 9/1-14, a big drop from the progged 400% for 8/18-24 due to Erin to ~1/2 the ACE for that week (likely MJO related as you said).

But then again, it’s 80% of the very active 2005-24 climo for near peak season. So, even if the 80% were to verify well, that would still mean an active period (even though not to the degree of the Erin week) and would end up way more active than for that period in 2024. Sep 1-14 of 2024 had only ~5-6 ACE, which is a mere <20% of the ~31 ACE avg for 2005-24. Compare that to the EW’s 80% prog, which would be ~25 ACE or 4-5 times as high as 2024.

Interestingly, the weeklies are still predicting above normal storm frequency during this time. We may still see a good amount of short-lived storms and hurricanes, but a lack of anything long-lived. My guess is the mjo will come back around to the Atlantic during the second half of September, which may open the door to more late season CV storms like last year.

[LarryWx]

The euro weeklies is showing well above normal ace in the short term (largely due to Erin), however, this is predicted to quickly fall off. The first half of September is predicted to be below normal, this is likely due to the mjo becoming unfavorable for the basin by then.

Indeed, the latest Euro Weeklies are showing only 80% of ACE for 9/1-14, a big drop from the progged 400% for 8/18-24 due to Erin to ~1/2 the ACE for that week (likely MJO related as you said).

But then again, it’s 80% of the very active 2005-24 climo for near peak season. So, even if the 80% were to verify well, that would still mean an active period (even though not to the degree of the Erin week) and would end up way more active than for that period in 2024. Sep 1-14 of 2024 had only ~5-6 ACE, which is a mere <20% of the ~31 ACE avg for 2005-24. Compare that to the EW’s 80% prog, which would be ~25 ACE or 4-5 times as high as 2024.

Interestingly, the weeklies are still predicting above normal storm frequency during this time. We may still see a good amount of short-lived storms and hurricanes, but a lack of anything long-lived. My guess is the mjo will come back around to the Atlantic during the second half of September, which may open the door to more late season CV storms like last year.

Yeah, if the MJO is in phases 8-1-2 then, watch out Conus especially.

[LarryWx]

12Z UK: for several runs has had this after Erin:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 156 HOURS
FORECAST POSITION AT T+156 : 15.9N 24.3W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 20.08.2025 156 15.9N 24.3W 1010 28
1200UTC 20.08.2025 168 15.7N 28.1W 1009 32

[LAF92]

12z Euro after Erin takes a wave through the Caribbean and gets it in the gulf something to keep an eye on in the future

[BobHarlem]

12z Euro ensembles animated to try to show the wave behind erin on here, quite a few wind up in the Bahamas.

[TomballEd]

12z Euro ensembles animated to try to show the wave behind erin on here, quite a few wind up in the Bahamas.

https://i.postimg.cc/9fRGPksY/64844100.gif

10% of the EPS at hour 360 show something in the Gulf, which is always interesting. 15 days out, I'm curbing my enthusiasm.

[Cpv17]

If something gets into the Caribbean, it’s probably not gonna end too well for someone. The 12z Euro/EPS has gotten my attention.

[convergencezone2]

The euro weeklies is showing well above normal ace in the short term (largely due to Erin), however, this is predicted to quickly fall off. The first half of September is predicted to be below normal, this is likely due to the mjo becoming unfavorable for the basin by then.

could mean that this might be one of those back-loaded seasons then.

[LarryWx]

12Z UK: for several runs has had this after Erin:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 156 HOURS
FORECAST POSITION AT T+156 : 15.9N 24.3W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
0000UTC 20.08.2025 156 15.9N 24.3W 1010 28
1200UTC 20.08.2025 168 15.7N 28.1W 1009 32

Followup to above:
0Z UKMET has a similarly placed TD following Erin vs the 12Z run:

NEW TROPICAL CYCLONE FORECAST TO DEVELOP AFTER 156 HOURS
FORECAST POSITION AT T+156 : 15.9N 28.1W

LEAD CENTRAL MAXIMUM WIND
VERIFYING TIME TIME POSITION PRESSURE (MB) SPEED (KNOTS)
-------------- ---- -------- ------------- -------------
1200UTC 20.08.2025 156 15.9N 28.1W 1010 33
0000UTC 21.08.2025 168 15.8N 30.4W 1009 29