2024 Global Model Runs Discussion (Out thru day 16)

[Teban54]

Two interesting tidbits on 0z ICON. For one, it shows development of a wave near Cabo Verde on 8/25, though it fluctuates between 1009-1011mb. This was also shown on the 12z run, and I believe it's the same wave that has a weak signal on the GEFS and EPS.



What I find a bit more interesting is a wave before that. The run shows a wave at 43W slowly curving up during 8/22-24 while remaining stationary, with a low that peaks at 1009 mb. While not clear from the precipitation map, it almost looks like a weak TD. The system is short-lived, though I can't tell if it's due to dry air or shear.



The real curiosity is not with this run alone, but with the trend. For the last 5 runs (shown below), you can see the wave becoming better defined, less strung out, and slower. I wonder if this will be some sort of a trend for model depictions of MDR conditions in general, either just for ICON itself or also for other models (it doesn't have to be specific to this wave).



Edit: Looking at 0z GFS, there is a very, very, very weak vorticity signature in the central Atlantic that slows down during the same time frame as ICON, becoming the most "well-defined" at 108 hours and then again at 144-150 hours. This is not even close to development, but I wouldn't be surprised if the system becomes more pronounced in later runs. (Watch the area around 40-43W.)

[Stratton23]

00z CMC is starting to show the flip, strong wave in the gulf and maybe a potential developing system in the eastern caribbean at the end of its run

[Stratton23]

The GFS is continuously trying to string out every bit of energy with these waves, which is why its continuously showing nothing developing in ant of its runs, this tells me that the GFS is having a very poor time seeing the switch coming, while the CMC operational is starting to see it

[Hammy]

Canadian is picking out 2-4 potential storms near month's end. Pretty much as I expected, the switch is going to be about a week or so later than normal thanks to the monsoon trough placement, but looks like things should happen pretty quickly in a week and a half.

[Stratton23]

Hammy yup its coming, even the GEFS through 240 hours ( 00z run) is starting to perk up a little bit more as well

[Stratton23]

EPS 00z lights up the basin like a christmas tree, very strong signal

[LarryWx]

Euro weeklies ACE forecast vs norm last 7 days (newest far right, which is 0Z of Sunday):

8/26-9/1: 60%/60%/50%/60%/50%/50%/50%; Norm 14
9/2-8: 110%/110%/110%/110%/120%/100%/110%; norm 15
9/9-15: NA/120%/90%/80%/90%/80%/100%; norm 16

So, the weeklies have been pretty consistently calling for ~7 for 8/26-9/1, 17 for 9/2-8, and 16 for 9/9-15. That would get ACE to ~95 after Ernesto finishes at ~55. The 1991-2020 avg for 9/15 is 70. That’s if these numbers aren’t underdone, which I think is likely. The signal for the last week is for a sharp ramp up with the peak in early to mid Sep after a somewhat quieter late Aug.

[Teban54]

0z GEFS is similar to 12z. Looks like now 0z and 12z are the strong ones, and 6z and 18z the weak ones. (Edit: Also note the slightly increasing support for a TS in the BOC or westernmost Caribbean.)

Can't see 0z EPS now without subscription, so I can't post.

[Hammy]

00z Euro gave up and said what hurricane season, even AIRS has nothing through Sep 2

[skyline385]

12z EPS is back with the NATL, the 0z was likely an anomaly and I wanted to see if 12z confirmed it which it didnt and considering switch flip is approaching, it should be safe to toss out that run for now.

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

https://i.imgur.com/S2PblSJ.png

Similar members on 12z GEFS

https://i.imgur.com/sV3T7sa.png

Yep, switch flip is almost here. Ensembles continue to slowly uptick every run.

[LarryWx]

00z Euro gave up and said what hurricane season, even AIRS has nothing through Sep 2

1) Indeed, but the 0Z EPS is moderately active 8/27-9/2 in the W basin starting with Caribbean.

2) I’m still going to watch to see if the AEW that departs Africa near Aug 24th is potent because 0Z ICON among others is suggesting it might.

[Stratton23]

It still seems like some folks are hugging operational runs too much, of course each run is going to be wildly different than the next , ensembles are the only guidance that matters beyond 5-7 days

[cycloneye]

Here is the wave around 10N that will emerge in 4 days.

[MEANINGLESS_NUMBERS]

Here is the wave around 10N that will emerge in 4 days.

https://i.imgur.com/PgnDRD9.png

That’s a good looking wave. Might be the best of the year so far.

[TomballEd]

Well, so, what does 2017, when there had already been 3 hurricanes in August by this date, have to do with 2024? We've had 1 hurricane, not a major, this month and the next supportable chance of a TC is at the very end of the month.

Can you post 2005 or 2020 to prove August is about to flip? BTW, a S-O-N heavy season is still possible (speaking of 2020).

We have had two, not one, August hurricanes this year.

Also unless I'm missing something, 2017 had two hurricanes by this date, not three.

Harvey was not yet a hurricane, so two hurricanes and a TS. My bad. But the point remains the tropics aren't about to explode. 2017, to this point, is not 2024.

[cheezyWXguy]

6z gfs seems to show hints of the cv wave that the ensembles are picking up in the longer term, starts to develop it at the end of the run near Cuba. Decent moisture pocket and favorable coloration with upper level anticyclone. This has a bit more of my attention than other model storms over the past week or so

[kevin]

Ensembles are starting to light up. 06z GEFS now has 4 AOI over the next 2 weeks, 2 waves coming from Africa, some closer cyclogenesis in the WCar or near Florida & some of its standard CAG stuff. Not a 'peak season ensemble' yet, but it starting to show signs of waking up. I know we're all thinking it's a very slow start, but if 2 or 3 of these systems develop over the next 14 days things could be very different soon.

[REDHurricane]

We have had two, not one, August hurricanes this year.

Also unless I'm missing something, 2017 had two hurricanes by this date, not three.

Harvey was not yet a hurricane, so two hurricanes and a TS. My bad. But the point remains the tropics aren't about to explode. 2017, to this point, is not 2024.

If we're defining "about to explode" as "going to produce a major hurricane within the next 7 days" then sure, but I can basically guarantee you that 2 (maybe even up to 3 if things progress much slower than expected but I personally doubt that'll happen) weeks from now there will be no more discussion of the season being cancelled or seriously busting relative to expectations. Whether the tropics start really blowing up in the last week of August or the second week of September shouldn't really matter all that much, this season is still extremely likely to meet the hyperactive threshold of 175 ACE or whatever it is, very likely to exceed 200 ACE in my opinion regardless of when "the switch" fully comes into fruition, and has at least like a 25-30% chance of surpassing 2017's ACE of 224.9.

I'll be happy to eat crow if I'm wrong, but either way I still think it's too early to begin doubting the seasonal forecasts put out by CSU, NCSU, NOAA, etc. when we're still nearly two weeks away from September and more than three weeks away from the climatological peak of the season. Will the Atlantic break the all-time ACE record as I predicted in my seasonal forecast submission? Probably not at this point since that would require more consistent activity throughout July/August, but until there's real evidence that the tropics aren't going to ramp up sometime in the next 2ish weeks I see no reason to believe that it won't happen.

[Teban54]

6z GEFS

[SFLcane]

Also unless I'm missing something, 2017 had two hurricanes by this date, not three.

Harvey was not yet a hurricane, so two hurricanes and a TS. My bad. But the point remains the tropics aren't about to explode. 2017, to this point, is not 2024.

If we're defining "about to explode" as "going to produce a major hurricane within the next 7 days" then sure, but I can basically guarantee you that 2 (maybe even up to 3 if things progress much slower than expected but I personally doubt that'll happen) weeks from now there will be no more discussion of the season being cancelled or seriously busting relative to expectations. Whether the tropics start really blowing up in the last week of August or the second week of September shouldn't really matter all that much, this season is still extremely likely to meet the hyperactive threshold of 175 ACE or whatever it is, very likely to exceed 200 ACE in my opinion regardless of when "the switch" fully comes into fruition, and has at least like a 25-30% chance of surpassing 2017's ACE of 224.9.

I'll be happy to eat crow if I'm wrong, but either way I still think it's too early to begin doubting the seasonal forecasts put out by CSU, NCSU, NOAA, etc. when we're still nearly two weeks away from September and more than three weeks away from the climatological peak of the season. Will the Atlantic break the all-time ACE record as I predicted in my seasonal forecast submission? Probably not at this point since that would require more consistent activity throughout July/August, but until there's real evidence that the tropics aren't going to ramp up sometime in the next 2ish weeks I see no reason to believe that it won't happen.

We play this game every year until there is 3 hurricanes spinning across the Atl 9/10