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Tropical 2021 hurricane season thread

accu35 said:
And now gfs is picking up on it. GOM is busy this year
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00z ICON has a wave mid Atlantic and coming off Africa that are on GFS but not as identifiable. If the bridge ridge occurs, these 2 could be a problem for the east coast.



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12z ICON dropping the 9/11 mid Atlantic depression further south, building the bridge in. Following GFS with 91L, although much weaker.

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Business is about to pick up. Looks like the Gulf could have trouble brewing again, and NC always has to be wary about canes in September.
 
The signal for genesis of an AEW in mid-Sep along with mainly W movement is still there on the 12Z EPS. However, regarding the strong AEW still progged by several models to come off Africa ~9/11, the trend is for a sharp recurve due to a weakness in the far E Atlantic, which has gotten more prominent on the Euro suites as the high is further west in the mid Atlantic Ocean.

So, it appears that there will probably be a strong AEW moving off 9/11 probably followed by a sharp recurve followed by an AEW moving off near 9/14-5 that likely then moves mainly W to WNW well out into the Atlantic. We’ll see though as that’s still 10 days out and much can change just like the changes with the 9/11 wave.

Here’s the 12Z EPS still showing a strong signal for a W to WNW moving AEW or two just after midmonth, which would need to be watched for late month:

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Per the 12Z GFS and CMC, that strong AEW over Africa that especially the Euro but also the ICON have been developing on 9/11 just offshore never recurves but instead stays weak and moves WSW in the E Atlantic. You can actually trace the vorticity/precip associated with it on the 12Z GFS then move W all of the way to the Lesser Antilles on 9/17 followed by it moving WNW into the Caribbean but staying very weak.
 
Per the 12Z GFS and CMC, that strong AEW over Africa that especially the Euro but also the ICON have been developing on 9/11 just offshore never recurves but instead stays weak and moves WSW in the E Atlantic. You can actually trace the vorticity/precip associated with it on the 12Z GFS then move W all of the way to the Lesser Antilles on 9/17 followed by it moving WNW into the Caribbean but staying very weak.


And just like that, the 12Z Euro doesn't recurve it. Instead it starts out like it will recurve, but then it turns back W, then WSW, and then SW while weakening. Also, it comes off about 12 hours earlier than the prior run and closer to the timing of the GFS/CMC though still slower than those. These run to run changes and model differences show me that it is still too early to make a definitive call on what this AEW moving off ~9/11 will or won't do. After all, it is still ~6 days away from the coast and a lot can change before then.


Old Euro run (0Z) is along the African coast moving back inland to the NE:
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New Euro run (12) is 400 miles to the WSW about to turn SW and weaken:
ecmop_12_h500_ta_h_0180.png
 
A little off topic but 25 yrs ago today Fran hit, still the only time in a hurricane I have ever felt scared or concerned....for 2-3 hrs we had near sustained hurricane force winds and gust into the 100-110 range......still by far the biggest wind I have ever seen or heard, and it was middle of the night so all you could hear was the howl of the wind and the crash of trees coming down......thought we were going to lose the roof several times.

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GaWx said:
0Z EPS is still very active in the MDR late in the run/something to watch for late Sept:
View attachment 90242
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12Z EPS for same time is not nearly as active as 0Z run:
ecmen_12_mslps_ta_h_0348.png

Edit: But regardless, I'm still keeping a wary eye on the vigorous AEW progged to move off Africa near 9/11. Earlier in this run, you can see a significant SW shift in the mean of this wave along with an increase in the number of members that don't recurve and instead that turn WSW vs the 0Z run.
 
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GaWx said:
12Z EPS for same time is not nearly as active as 0Z run:
View attachment 90275

Edit: But regardless, I'm still keeping a wary eye on the vigorous AEW progged to move off Africa near 9/11. Earlier in this run, you can see a significant SW shift in the mean of this wave along with an increase in the number of members that don't recurve and instead that turn WSW vs the 0Z run.
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Thanks, as always, for the ongoing analysis and keen eye, Larry ... ?
 
The same strong AEW currently over central Africa that the models have for many days been having move off 9/10-11 and becoming a TC almost immediately on a number of Euro and Icon runs is the strongest on the new GFS run that I can recall. Even though it weakens, it is now the 3rd GFS run in a row with a trackable AEW getting into the Caribbean 9/17 and is the most energetic it has been when getting there (strong wave). This once again gets to Cuba/FL Straits/S FL late on 9/20 and tells me once again that this could conceivably threaten the Caribbean ~9/17-20 followed by the CONUS starting ~9/20.

Climo says that a scenario like this isn’t at all far-fetched for an AEW moving off ~9/10, especially in La Niña.
 
The 6Z GFS/GEFS and EPS are continuing the idea that the AEW moving offshore Africa 9/10 (GFS) or 9/11 (Euro) (is the same AEW) may very well eventually be something to contend with. The 6Z GFS is the 4th run in a row that gets it near FL ~9/20. Also, this run suggests there may be another active wave a few days behind it. Also, note the strong E US ridge being suggested for around that period.
 
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