ATL: ERIN - Post-Tropical - Discussion

[Buck]

What is current ACE for Erin.

Erin stands at 32.2 ACE at the moment.

https://tropical.atmos.colostate.edu/Re ... thatlantic

And thankfully, we can also track ACE on the NHC website now, too. https://www.nhc.noaa.gov/data/tcr/

[CrazyC83]

This is completely unofficial, but this is what I would have for the BT for Erin.

AL052025, ERIN, xx,
20250810, 1200, , LO, 14.8N, 20.1W, 30, 1010,
20250810, 1800, , TD, 15.3N, 21.6W, 30, 1009,
20250810, 2200, L, TS, 16.1N, 22.7W, 35, 1008,
20250811, 0000, , TS, 16.5N, 23.4W, 40, 1007,
20250811, 0600, L, TS, 17.1N, 25.0W, 40, 1007,
20250811, 1200, , TS, 17.3N, 27.2W, 40, 1007,
20250811, 1800, , TS, 17.4N, 29.3W, 40, 1006,
20250812, 0000, , TS, 17.5N, 31.3W, 45, 1004,
20250812, 0600, , TS, 17.4N, 33.3W, 45, 1004,
20250812, 1200, , TS, 17.2N, 35.3W, 40, 1005,
20250812, 1800, , TS, 17.0N, 37.2W, 40, 1006,
20250813, 0000, , TS, 16.8N, 39.1W, 40, 1006,
20250813, 0600, , TS, 16.6N, 41.0W, 40, 1006,
20250813, 1200, , TS, 16.4N, 42.8W, 45, 1005,
20250813, 1800, , TS, 16.3N, 44.4W, 45, 1005,
20250814, 0000, , TS, 16.2N, 46.0W, 45, 1005,
20250814, 0600, , TS, 16.3N, 47.5W, 50, 1003,
20250814, 1200, , TS, 16.4N, 48.9W, 55, 1001,
20250814, 1800, , TS, 16.6N, 50.4W, 55, 1000,
20250815, 0000, , TS, 16.9N, 51.9W, 60, 998,
20250815, 0600, , HU, 17.4N, 53.6W, 65, 997,
20250815, 1200, , HU, 18.0N, 55.3W, 65, 996,
20250815, 1800, , HU, 18.7N, 56.8W, 70, 991,
20250816, 0000, , HU, 19.3N, 58.6W, 80, 982,
20250816, 0600, , HU, 19.5N, 60.4W, 95, 968,
20250816, 1200, , HU, 19.6N, 62.1W, 130, 934,
20250816, 1600, I, HU, 19.7N, 63.1W, 145, 913,
20250816, 1800, , HU, 19.8N, 63.4W, 140, 918,
20250817, 0000, , HU, 20.0N, 64.5W, 125, 934,
20250817, 0600, , HU, 20.3N, 65.8W, 110, 940,
20250817, 1200, , HU, 20.7N, 67.0W, 105, 942,
20250817, 1800, , HU, 21.5N, 68.0W, 100, 947,
20250818, 0000, , HU, 22.1N, 68.9W, 105, 946,
20250818, 0600, , HU, 22.5N, 69.8W, 110, 943,
20250818, 1200, , HU, 22.9N, 70.5W, 120, 933,
20250818, 1800, , HU, 23.5N, 71.0W, 110, 939,
20250819, 0000, , HU, 24.0N, 71.4W, 100, 947,
20250819, 0600, , HU, 24.5N, 71.8W, 90, 954,
20250819, 1200, , HU, 25.2N, 72.1W, 80, 958,
20250819, 1800, , HU, 26.1N, 72.5W, 80, 959,
20250820, 0000, , HU, 27.2N, 72.8W, 80, 959,
20250820, 0600, , HU, 28.3N, 73.2W, 80, 954,
20250820, 1200, , HU, 29.6N, 73.7W, 85, 945,
20250820, 1800, , HU, 30.7N, 73.6W, 85, 941,
20250821, 0000, , HU, 32.1N, 73.3W, 85, 940,
20250821, 0600, , HU, 33.6N, 72.6W, 80, 945,
20250821, 1200, , HU, 34.9N, 71.6W, 80, 948,
20250821, 1800, , HU, 35.9N, 70.1W, 75, 952,
20250822, 0000, , HU, 36.9N, 68.4W, 75, 951,
20250822, 0600, , HU, 37.9N, 66.5W, 75, 950,
20250822, 1200, , HU, 38.6N, 64.6W, 75, 950,
20250822, 1800, , EX, 39.5N, 61.4W, 75, 951,
20250823, 0000, , EX, 40.5N, 57.5W, 75, 952,

Some highlights:

* Genesis is pushed up to BEFORE Cape Verde, based on the ASCAT pass that showed a probable LLC around 01Z August 11. That adds two landfalls in the islands in the early life, as the ASCAT pass had 38 kt winds, so a 40 kt intensity is analyzed.
* Most of the early life is otherwise only changed slightly to smooth things out.
* The rapid intensification period is also smoothed out, knowing data points had to be interpolated. The pressure dropped 78 mb in 20 hours on this analysis!
* The peak intensity is estimated to be 145 kt at 16Z August 16, a non-synoptic time. It was around that time that Recon measured 154 kt at flight level, a dropsonde with much higher winds, and a pressure estimated at 913 mb. Most of the weight goes to the flight-level winds, although a bit of weight goes to the dropsonde. The SFMR (which was as high as 170 kt) is ignored. It was likely already weakening by synoptic time, so that point is used as the peak.
* The eyewall cycle is also adjusted, mostly downwards to a low of 100 kt (instead of 110 kt), reflecting the lower Recon readings. The secondary peak is largely unchanged.
* After the secondary peak, the winds and pressure went out of whack (not unexpected, and common with sprawling storms, look at Irene, Igor and Sandy for examples). Generally, in those storms, 90% isn't a good wind relationship for the intensity due to somewhat weaker convection. The intensities were brought down to 80-85 kt instead of 85-95 kt in that time. There was no reliable SFMR data, so past experience was used here. Yes, that means a 940 mb pressure with a storm of 85 kt, but it would not be unprecedented in such a storm.

[cycloneye]

 https://x.com/MattDevittWX/status/1959075379987235140

[syfr]

 https://x.com/MattDevittWX/status/1959075379987235140

Outside of any cone at any time?

[Ubuntwo]

Erin is the most intense Atlantic category 5 to never make landfall as a TC, of only three. Interestingly, all of those 3 occurred within the past six years.

[Teban54]

Back when Erin first formed and models were suggesting a recurve in the western Atlantic as a major hurricane, it reminded me of Earl 2022 and Ernesto 2024. The two recent storms both have the same letter E and similar forecast tracks as Erin, and both were forecast to become Cat 4s as they recurve. Ernesto even had a similar time frame (mid-August) as Erin.

However, Earl and Ernesto eventually fell short of expectations and peaked as Cat 2s, due to dry air and shear issues being more severe than anticipated. Both were treated as indicators of inactive seasons at that time (Earl just after an anomalously quiet period, and Ernesto just before one), and people started writing off both years as duds after their underperformance. Yet, 2022 and 2024 ultimately became highly destructive seasons, with Fiona, Ian, Helene and Milton.

It's quite fascinating to see Erin not following the footsteps of these recent E storms, instead becoming a "success story" with an extreme RI to Cat 5 in the deep tropics -- more of a Fiona repeat than Earl (minus the Atlantic Canada landfall, thankfully).

While the basin will likely enter a (relative) lull after Erin, we should keep in mind the late season impacts in 2022 and 2024, when the seasonal outlooks were much bleaker than 2025's right now. If those seasons can make a comeback after Earl and Ernesto, it's very plausible for 2025 to do so after Erin.

[Category5Kaiju]

Erin is the most intense Atlantic category 5 to never make landfall as a TC, of only three. Interestingly, all of those 3 occurred within the past six years.

Can't remember exactly who proposed the idea (I think it was somewhere on Storm2k several years ago), but they had an interesting theory that Category 5 "fish" storms might become more common in coming years considering how anomalously warm the Atlantic Ocean has generically become. We'll have to see if this really comes to fruition, but there's no denying that the anomalously warm Western Atlantic helped fuel Erin to become what it became.

[Woofde]

Erin cut a massive cold wake over what was anomalously warm waters. Regardless of the lower peak core intensity after EWRC, there was some serious energy transfer taking place.

[CrazyC83]

Erin is the most intense Atlantic category 5 to never make landfall as a TC, of only three. Interestingly, all of those 3 occurred within the past six years.

Unless early-life landfalls are added in Cape Verde (due to an earlier genesis time), that is indeed correct. The old record I believe was 925 mb with Lorenzo.