The Atlantic has been quiet and for good reason, but not completely quiet, is this a sign of things to come?  

Russell has been quieter this year on the storm blog writing front - so far- regarding Atlantic weather, in particular Gulf storms, but just past the halfway point, there has not been ‘no’ activity.  

Despite the widely anticipated ‘above average’ season there is one ingredient, a key component, which is needed for this year’s meteorological cocktail, which has yet to materialise. We will get to this later. However, as mentioned the Atlantic basin has not been completely quiet.  

So, what?  

Firstly, not all the ingredients have been in place, but secondly and perhaps most importantly, despite this, we have had storm formation, in fact major storm formation. Rather than a cocktail, we have had a mocktail. 

Notably, two Category 5 storms have formed this year, in largely unfavourable conditions atmospherically across the Atlantic. This is due in part to a weak, but on-going La Niña signal from the East Pacific combined with a strong warming signal in the West, which is perhaps more pronounced than usual. Convection (the tendency for air to lift and under the right conditions, the atmosphere to stretch upwards) has been semi permanently routed over the western Pacific, unsurprisingly, where storm activity continues to be well above average.  

No Hurrah from the Sahara  

Conversely the Atlantic, the western Atlantic has experienced an environment of sinking air, unfavourable for the deep convection that is usually required to sustain strong storms. This has been combined with a setup over the eastern Atlantic to encourage a fairly consistent surge of Saharan dust feeding off Africa into the Atlantic introducing dry air and dust which inhibit thunderstorm formation to initiate tropical system developments.  

Wave goodbye to Cape Verde storms?  

Recently also, conditions across the Indian Ocean (to the east of Africa) have led to some suppression of ‘waves’ which travel west across Africa which can encourage thunderstorm formation off the West coast. Interestingly this wave suppression across the Indian Ocean will help lock-in a continuation of the favourable environment across the West Pacific as many businesses and communities continue “Typhoon watch”, it is after all, all connected.  Exacerbated by an on-going marine heatwave (ocean surface temperatures well above average) in these regions, adding a bonus ingredient to the already supercharged environment for storm production.  

So, no Activity in the Atlantic? – not so.  

Despite all of that, in the Atlantic, we have still had storms. When we talk about ingredients, it is becoming clearer that warm water at depth is the ‘trump card’ when it comes to storm development. Twice this year we have seen these systems supercharge themselves from tropical storms to major hurricanes in timescales of a few days, possibly quicker. This is occurring in largely unfavourable environments with at least moderate levels of vertical wind shear and areas of generally sinking air, or both.  

In years gone by, we would not have expected these storms to become major, possibly not even form at all. This is perhaps one of the most profound responses to warming oceans, whilst this warming and cooling does adhere to global cycles, it is becoming evident that these warm periods are becoming more frequent and more intense. What is most striking is the increasing warmth at depth known as the ‘Oceanic heat content.’ Much like a bath, the more hot water you add, the longer it takes to cool, and in recent years, the ocean - in these parts - is retaining more heat at depth.  

Time for a new ‘super-charger’ threshold?  

Lastly, it is widely accepted that 26.50C + is the threshold that supports hurricane formation. However, we are starting to see a surge in temperatures approaching 30 degrees in places, which seem to have the impact of rapid intensification, sometimes regardless of atmospheric conditions; the speed and intensity surpassing nearly all model calculations.  

So, as the title suggests, the fact we have seen major hurricanes this year in largely unfavourable conditions atmospherically is perhaps more important and concerning than the suppressed activity overall.  

Imagine what we could be seeing this year if the conditions became ‘right’ across the Gulf region… the window for this is closing as we approach October, but the season still has 2 months to go. If not this year, what about the next? 

Category containment 

10 years ago, the notion of a “Category 6” was laughable, despite Hurricane Allen reaching 190mph in 1980, seen as a one off. However, storms such as Milton, Dorian, Wilma - not to mentioned Patrica (record 215mph winds) albeit into the West Coast of the US, have all equalled or surpassed that in the last 10 years. Could/should the sealing of a Cat 5 at 157mph be replaced with increased banding in the ‘major’ category, or even a Cat 6…? Mathematically at least, it looks like the Cat 5 ceiling is premature.  

2025? 

Whilst we are not seeing the wind records being matched, there have been two storms - and possibly more - which reached the highest category perceivable -Category 5, in largely ‘unfavourable’ conditions. Imagine what we could have seen if the weather cocktail maker had added some spicier ingredients to the mix? 

It should be noted that at the time of writing, Tropical system Imelda, soon to become a Hurricane may strengthen quickly on its way to Bermuda, unlike Humberto which will spare the island from the direct hit, thankfully; the next inline looks to be steering much closer, and weaker than its predecessor.  

That being said, over the warmer waters to the west of Bermuda, Imelda will strengthen and could reach Major hurricane status on its approach, the last storm to do so was over 100 years ago. The exact track of the storm and the orientation of the rain bands will determine the local impacts, thankfully the consensus is that the storm forward speed is expected to increase, so the duration of the worst weather will be reduced. However, a lot can change in 24-hours, so insurers should remain vigilant.    

Russell will continue to keep an eye on this, and the rest of the Atlantic for this season, whilst looking forward to 2026 where signs are already emerging to suggest more favourable conditions than we have seen this year… if not this year, could next year be the big one?