This season is going to be very interesting to watch unfold.
I wouldn’t buy what the Euro seasonal is selling verbatim. Last year it was terrible, and we see a rapidly developing Niño. I think this probably caps activity should ENSO continue on this pace, as we get a higher end moderate Nino by the peak of the season.
There’s really a lot to unpack, but here are some initial thoughts on why there’s so much uncertainty:
1. The Atlantic is outrageously warm
It’s actually extraordinary how consistent the warming has been. Here’s a 90 day SST anomaly. Note the Nino developing and the simultaneous scale of warming anomalies throughout the Atlantic basin.
Speaking to the depth, it’s exceptionally expansive for this time of year, particularly in the MDR (including the Caribbean.
2. The +AMO
The continuation of the active cycle of the AMO also heightens risk.
The AMO itself heightens the atmospheric conditions necessary for activity, but as we saw last year, it only takes you so far.
3. Instability (or lack thereof)
The combination of SAL outbreaks (which are normal to an extent) and instability will be critical to the kind of season we have. In recent years, stability in the eastern MDR has dramatically limited development, forcing TC genesis toward the Caribbean and homebrew areas of the Gulf and SE coast. With the Nino likely to increase shear, especially in the Caribbean, if the eastern MDR can’t destabilize, the Caribbean shredder could make this a quiet season.
It’ll be interesting to see how the early activity off Africa handles the environment.
4. Shear location
What the varying forecasts on the season tell me is that this is a thread the needle season. There’s no more important factor in the impact on the Antilles and US than shear location.
With a niño we’re likely to see activity further east, with a general recurve pattern. However, there are likely to be windows for closer development, and if general trades are weaker and/or TUTT and wave breaking activity is further north than anticipated, watch out. That’s impossible to tell at this stage.
For now, the Atlantic looks quiet, but it may be worth watching in two-three weeks as the GFS ensemble show a potential CAG pattern setting up. You’d expect to see the EPAC spark up first and then see a development window transition to the western Atlantic.