2025 Atlantic Hurricane Season

[donsutherland1]

For reference, model skill scores:

Global Models:

Ensembles:

Hurricane Models:

 

 

 

[Roger Smith]

I was thinking about 1998 and the only thing about that tropical season that I recall is Mitch at the end of the season. Now we're looking at a pretty uneventful season in general ending with Melissa which could become a high impact storm for Jamaica, eastern Cuba and or Haiti. 

[NorthHillsWx]

If forecasts hold, Melissa all but guarantees we will finish the season above average ACE. This legitimately did not seem possible going into the third week of September 

[GaWx]

1 hour ago, NorthHillsWx said:

If forecasts hold, Melissa all but guarantees we will finish the season above average ACE. This legitimately did not seem possible going into the third week of September 

There was only 39 ACE through Sept 16th. There has been 67 ACE Sept 17th through 12Z today with likely 20+ more to come from Melissa, alone. This heavy late season vs earlier has been more common in recent years, especially during La Niña.

[WxWatcher007]

Grading my peak season forecast. Missed Melissa by 11 hours. 
 

1 hour ago, WxWatcher007 said:

Alright, it's time to grade the peak season forecast. As you know, the period between August 20 and October 20 is graded. Melissa, our third category 5 hurricane of the season, was officially designated 11 hours after my forecast ended, but them's the breaks. Here's how the numbers shake out. 

Peak Season Forecast (Aug 20-Oct 20)
Named Storms: 10 (7)
Hurricanes: 6 (3)
Major Hurricanes: 3 (2)

Fernand, Gabrielle (MH), Humberto (MH), Imelda (H), Jerry, Karen, Lorenzo

Missing Melissa so closely obviously hurts  

The numbers were fine overall. The biggest overestimation ended up being the number of hurricanes. This season is truly the definition of quality over quantity, with 60% of the limited hurricane activity consisting of C5s. This is only the second season on record with more than 2 C5s. In 2005 we had four. 

The overall forecast that we would have a similar peak season lull to 2024, and then have a highly active back half of the peak season was spot on. Even the more specific forecast of activity halting until after September 20 was nailed. That is a huge win, because many were losing confidence that there would even be meaningful activity given the stability issues in the basin. This alone puts me in good shape with the forecast grade, but let's examine each of the factors I analyzed in August. 

1. ENSO--I was right that cool ENSO would dominate the season, and that ended up being the case. That wasn't too hard a call given that we were in a Nina watch. The ENSO did end up facilitating lower wind shear in the basin, but the picture is a little more tricky as you'll see below. 

2. WAM--I expected an active WAM, but less so than last year where we had so many robust waves that it may have triggered more SAL and stability in the basin. The active WAM is evidenced by the strong waves that continued into October, and gave me some much needed help with my NS forecast at the end of the forecast period. Importantly, it also looks like after the wave that eventually became Melissa that wave train ended, right in alignment with my forecast. 

3. Wind shear--this is the first spot where I really ding myself. I was right that shear would be on the lower side off the east coast and Caribbean, and that was true.

Off the east coast, note the higher than normal shear in part of September and then the drop in late September into October. Decent. 

 

The Caribbean, however, was a powder keg waiting to explode. We see that now with Melissa being the only tangible wave to get to the Caribbean. 

I was dead wrong when I thought that anti-cyclonic wave breaking wouldn't be an issue in the basin this season. It was, and led to all of the TUTTs that absolutely gutted the basin of activity during the first 2/3 of September. Once that subsided, the basin lit up. 

4. SST/OHC--the second biggest call of the season was accurately predicting that the defining feature of the season would be activity in the SW Atlantic. 

The Atlantic SST distribution became favorable for activity right before peak season, and it produced. If anything, we underperformed given the complete lack of activity in the Caribbean and Gulf, which I didn't anticipate to this extent. Erin's wake recovered, as I expected, and we saw high end activity in the SW Atlantic during the period. 

5. MJO & CCKW--As expected, things became a lot more favorable once the MJO flipped to favorable the second half of the peak. The dates do not line up perfectly with my peak season forecast but as Phil Klotzbach notes 2025 is tied with 1941 and 2024 for the most Atlantic major hurricane formations (3 including Melissa) between Sept 22 and Oct 25. More on point, since 1970, only 7 seasons have had 5+ NS between Sept 17 and October 9, 2024 and 2025 are two of them. 

6. Stability, dry air, and SAL--I really was a believer that the stability issues that we've had this decade in the tropical Atlantic would be an inhibitor early in the forecast period, and that was really right. That will be a key factor in the overall numbers being lower for some seasonal forecasts. This has been very hard to overcome in August and September in the eastern Atlantic. 

That said, this statement was proven to be right:

 

The activity would follow the wave train moistening the environment and waves getting to the western Atlantic. Surprisingly, we didn't get Gulf for Caribbean activity. Even the CAG signal that was present on the models at the start of October didn't work out. Odd, but the SW Atlantic was still a hub of activity. 

Overall
I called for a significant lull akin to 2024, followed by another high end and backloaded peak season. Two major hurricanes, one a C5, certainly fits the bill for effectively a four week peak. It seems as if the season will rapidly shut down after Melissa (again, outside the forecast period), but that seems to be another good call. There may be an uptick in the NS numbers with that possible subtropical event off the Mid-Atlantic a few weeks ago, but we grade as the numbers are as of October 20. I thought the Gulf would be quieter, but not completely dead. I called for a hurricane strike on the east coast and that missed, but only because we had a rare fujiwara interaction between Imelda off the southeast coast and Humberto, which unexpectedly rapidly intensified into a C5. We did not continue our streak of continental US MH landfalls. Fine by me. 

Grade: B+ 

 

 

Seasonal Grades

2019 Grade: B+
2020 Grade: A-
2021 Grade: C
2022 Grade: B
2023 Grade: A
2024 Grade: B
2025 Grade: B+