Invest 91L - 40/70

[olafminesaw]

Even with the GFS coming south to start the run, if I take it's position at hour 78: there have been 20 storms since 1980 to pass within 100 miles of that point in September, of which only 2 made landfall in the US, the rest recurved well east. The two exceptions are Hugo and Georges (1998). Georges moved through the heart of the Greater Antilles hitting every island along the way. It is the furthest south of this grouping in the Caribbean as well, so a track south of the islands would be unprecedented 

[GaWx]

12Z:
-Euro: has a TS in the MDR that later weakens to a weak low as it crosses the Lesser Antilles and then goes through Caribbean disorganized/very weak

-UKMET: no TC again/low too weak to be classified a TD

[GaWx]

The 12Z EPS has one member from 91L hit FL, another headed toward the Gulf, and a couple of others not far from hitting the NE US as they recurve. But overall, that’s still pretty quiet for CONUS. Interestingly, there’s more Conus hits from other systems, mainly homegrown stuff.

[BarryStantonGBP]

41 minutes ago, GaWx said:

The 12Z EPS has one member from 91L hit FL, another headed toward the Gulf, and a couple of others not far from hitting the NE US as they recurve. But overall, that’s still pretty quiet for CONUS. Interestingly, there’s more Conus hits from other systems, mainly homegrown stuff.

Oi lad there’s another signal separate from 91l that might go into the gulf and score a goal in the gulf net that I posted on the main thread

Gabby looks like she won’t do anything at this point

[GaWx]

 For the record, today’s 12Z JMA moves much more quickly as it gets near Bermuda at 192! What’s up with that? This is actually consistent with yesterday’s 12Z JMA.

[MJO812]

0z

[GaWx]

0Z:

-The UKMET is again too weak with the low to classify it as a TD.

-The 0Z CMC is similar to the GFS in being further S than its prior run and is close to the 0Z GFS as of 144.

 

 

[NorthHillsWx]

The idea this becomes a carribean storm is increasing. One other thing to note is several models show quite a bit of wind shear when the system approaches the islands. Perhaps they are seeing a shallower system that rides further south. Definitely an interesting track evolution from whatever forms here. Might have some hurdles ahead of it but I’d say the threat to land has increased markedly 

[GaWx]

1. 0Z Euro has no TC from this. That weak low into CHS late is home-grown.

2. 6Z GFS is way OTS, even E of Bermuda.

3. 6Z Icon is much weaker at the Lesser Antilles at 120.

[BarryStantonGBP]

1 hour ago, GaWx said:

1. 0Z Euro has no TC from this. That weak low into CHS late is home-grown.

2. 6Z GFS is way OTS, even E of Bermuda.

3. 6Z Icon is much weaker at the Lesser Antilles at 120.

Ngl what if this becomes a struggle bus that dissipates in the caribbean

[WxWatcher007]

I think all the model chaos just speaks to the uncertainty around if/when/where 91L develops. Everything kind of flows from there so an error in the short term means dramatically different outcomes in the long term. 

[olafminesaw]

Of the 22 systems since 1980 to pass within 100 miles of the British Virgin Islands in September, 5 made landfall in the us (22%). This feels like a reasonable benchmark based on model consensus, although as Wxwatcher007 says above, there is a high degree of uncertainty until a LLC develops. I think odds of this system never developing at all have gone up this morning with lots of shear potentially across the Carribean.

[GaWx]

24 minutes ago, olafminesaw said:

Of the 22 systems since 1980 to pass within 100 miles of the British Virgin Islands in September, 5 made landfall in the us (22%). This feels like a reasonable benchmark based on model consensus, although as Wxwatcher007 says above, there is a high degree of uncertainty until a LLC develops. I think odds of this system never developing at all have gone up this morning with lots of shear potentially across the Carribean.

 Thanks. Over the longer term and including all months, ~40% of TCs passing near the Virgin Islands later hit the Conus. The % is probably highest in Jul/Aug/first half of Sept.

[olafminesaw]

49 minutes ago, GaWx said:

 Thanks. Over the longer term and including all months, ~40% of TCs passing near the Virgin Islands later hit the Conus. The % is probably highest in Jul/Aug/first half of Sept.

Good point, there's a pretty big difference between the beginning and end of September climatologically. Also not a huge data set to draw firm conclusions on.

[NorthHillsWx]

Definitely an increase in models that either don’t develop this at all or keep it weak. Likely a main reason near term track guidance keeps shifting south. Environment around the islands looks fairly hostile for whatever makes it there 

[MJO812]

Gfs and Icon doesn't have storm anymore

[GaWx]

16 minutes ago, NorthHillsWx said:

Definitely an increase in models that either don’t develop this at all or keep it weak. Likely a main reason near term track guidance keeps shifting south. Environment around the islands looks fairly hostile for whatever makes it there 

12Z rundown so far:

Icon and GFS have almost nothing unlike recent runs.

CMC is so far (through 78) coming in much weaker with no closed LLC.

UKMET once again has no TC.

Edit: But fwiw JMA still has it in the MDR at 72 (1008 mb TC):

[yoda]

https://x.com/AndyHazelton/status/1963994545768608055

 

[MANDA]

Looking to me like 91L might be DOA.  Just looking quite hostile in the path ahead of it.  Shear and dry air abound.  Kind of makes sense why models that had it developing kept in very small...like it found the sweet spot in a very hostile environment.  Not expecting much from this now, IMO.  PERHAPS, MAYBE some remnant of it eventually makes it to western Caribbean where conditions would be more favorable but that looks like a long shot at the moment.

We're kind of back where we started....looking for home brew stuff to pop.

[MJO812]

3 minutes ago, yoda said:

https://x.com/AndyHazelton/status/1963994545768608055

 

This is why you have to take anything past 240 , heck 200 hours with a grain of salt.

[TheDreamTraveler]

Actually insane seeing the GFS just dropping that storm suddenly after showing it consistently for so long lmao

 

Are we just going to have a backloaded season again like last year? Kinda crazy how quiet it's been when we're basically in the peak of season.

[yoda]

23 minutes ago, yoda said:

https://x.com/AndyHazelton/status/1963994545768608055

 

https://x.com/AndyHazelton/status/1963980757417799798

 

[GaWx]

1 hour ago, TheDreamTraveler said:

Actually insane seeing the GFS just dropping that storm suddenly after showing it consistently for so long lmao

 

Are we just going to have a backloaded season again like last year? Kinda crazy how quiet it's been when we're basically in the peak of season.

 Nobody knows, which is what makes forecasting discussions so interesting.
 
 For comparison purposes, here are some very quiet periods during climo active dates of other non-El Nino seasons during the current active era:

-In 2024, there were 0 TCs during the 19 days 8/21-9/8.
-In 2022, there were 0 TCs in August.
-In 2016, there were 0 TCs Sep 4-11 and 0 H Sep 3-28.
-In 2013, there was no H til 9/11.
-In 2001, there was no H til 9/8

———-

Back to 91L:

12Z Euro has no TC from this in the MDR although something forms later in the subtropics. So, the highly unreliable JMA, especially when it’s on its own, is the line holdout of this cycle for a TC in the tropics from this.

 

Edit:

 For record-keeping purposes now that the rest of the run has been released, the 12Z JMA is a bit slower than the prior two. But it still has a similar idea of an early recurve with a H moving N along 60W 144-192.

[nycwinter]

dr mccoy it's dead jim...

[WxWatcher007]

32 minutes ago, TheDreamTraveler said:

Actually insane seeing the GFS just dropping that storm suddenly after showing it consistently for so long lmao

 

Are we just going to have a backloaded season again like last year? Kinda crazy how quiet it's been when we're basically in the peak of season

21 minutes ago, GaWx said:

 Nobody knows, which is what makes forecasting discussions so interesting.
 
 For comparison purposes, here are some very quiet periods during climo active dates of other non-El Nino seasons during the current active era:

-In 2024, there were 0 TCs during the 19 days 8/21-9/8.
-In 2022, there were 0 TCs in August.
-In 2016, there were 0 TCs Sep 4-11 and 0 H Sep 3-28.
-In 2013, there was no H til 9/11.
-In 2001, there was no H til 9/8

———-

Back to 91L:

12Z Euro has no TC from this in the MDR although something forms later in the subtropics. So, the highly unreliable JMA, especially when it’s on its own, is the line holdout of this cycle for a TC in the tropics from this.

My thought hasn’t changed on that so far. Although I was on board with 91L developing, I still think the basin overall will continue to be hostile until mid September or more likely after the 20th.

[WEATHER53]

2 hours ago, MJO812 said:

Gfs and Icon doesn't have storm anymore

Starting to be like the snowstorm models 

[BarryStantonGBP]

1 hour ago, WxWatcher007 said:

My thought hasn’t changed on that so far. Although I was on board with 91L developing, I still think the basin overall will continue to be hostile until mid September or more likely after the 20th.

Some models show an African wave and a cag around mid to late month

[Wannabehippie]

Tons of dry air out there right now. Even the NHC is making notes about it now how it will inhibit any development for the next few days. Unless that dry air lifts up, or otherwise gets out of the way, this will be a whole lot of nothing.

[WxWatcher007]

1 hour ago, BarryStantonGBP said:

Some models show an African wave and a cag around mid to late month

To be clear 91L still has a chance. I’m more skeptical about a CAG especially mid month. That’s outside of climatology as @GaWx has noted. Late month and especially into October is prime time for that though. Anyone thinking we’re in for a quiet season because of conditions currently should look at what was posted earlier. This decade especially has been known for strongly backloaded seasons. 

[GaWx]

9 minutes ago, WxWatcher007 said:

To be clear 91L still has a chance. I’m more skeptical about a CAG especially mid month. That’s outside of climatology as @GaWx has noted. Late month and especially into October is prime time for that though. Anyone thinking we’re in for a quiet season because of conditions currently should look at what was posted earlier. This decade especially has been known for strongly backloaded seasons. 

 In addition:

 The last few GEFS and EPS runs have forecasted MJO in the relatively favorable phases of 2, 1, and 8 through Sept. 19 and this would probably extend at least through the rest of Sept per longer term model guidance and climo: