I wanted ot post a quick update on Hurricane Season as many of the seasonal forecasting spots have issued updates to their seasonal totals and nearly all have increase the number of named storms, hurricanes and major hurricanes.
This may all seem very bad.
It isn’t.
But it isn’t completely meaningless, either.
Many of these outlets are increasing the total number of storms for the remainder of the season based on just how warm the waters in the Atlantic are this summer.
WARM WATER
The Atlantic Ocean is quite warm. Everywhere.
In fact, for how anomalously warm the Pacific is given this El Nino, the Atlantic is almost as warm. Not pictured here, but off the coast of Europe right now they are experiencing a “MArine Heatwave” or sorts where the water temperatures are running up to 4C higher than normal.
The map above is Sea Height Anomaly. This measures how much higher the water is than normal. It is a good proxy for sea temperature. Because as things warm up, they expand. And as the water expands, it ends up being higher than it normally is. And we can measure that with satellites!
The map above shows that a lot of the water in the Atlantics is much higher than normal. And look in the Gulf. Wow. The chunks of blue and red close to each other off the northeast coast are eddies in the water that gives it that appearance.
On top of that, the depth of the 26C isotherm (something that is important for hurricane and major hurricane development) is deeper and more robust than this time last year. This year is the image below on top, last year is on bottom.
So the water is hot and that warmer water is also deeper than it was last year.
And looking back, the last time the Gulf and Caribbean were this warm was back in 2020. Below is not a great 1-to-1 look as the folks at AOML have pulled the plug on offer these maps publicly, but the map on the left is from 2020 on September 12. On that map everywhere green to yellow to red is a depth of at least 40m. On the map on the right, everywhere not black is a depth of greater than 40m.
Again, not a great 1-to-1 but it does show that the Gulf is rather warm.
WHAT DOES THAT MEAN?
I know what you may be thinking: “So, what then? The warm water wins?”
Not directly. But yes. Sort of.
El Nino’s shear – at a basic level – is due to the unequal heating and cooling of the two ocean basins. Below, in the diagram on the left, the yellow arrows indicate the general motion of the air. At the surface the air moves from east to west then aloft from west to east. This added west-to-east wind aloft is part of the shear that helps to keep tropical cyclones from developing as quickly.
During a La Nina, you can see that, again very generally, the wind is flipped and the wind aloft is moving from east to west. And since tropical systems move from east-to-west also, this limits the amount of shear they – again, very generally – encounter.
In a Neutral year, the wind depends on the situation, time of summer, and overall conditions and there isn’t any background forcing at work.
This year, with both ocean basins being warm, the battle will be about ‘which one is warmer?’ and ‘How does that influence any atmospheric connections?’
The very short, and incomplete, answer is that it will likely reduce the general background shear that is in place across the Atlantic. To what extent? We don’t know.
But given the current ocean temperatures, any reduction in shear that coincides with a passing Kelvin Wave or MJO-favorable situation will increase the potential for activity in the Tropical Atlantic and increase the potential for a tropical storm or hurricane to materialize. Generally.
THE NEXT FEW WEEKS / MONTHS
During the next few weeks we may see a bit of an uptick in the activity in the Atlantic, but I don’t think we see much before the end of the month. One or two named storms are possible, but they are more likely to be “fish storms” than landfalling trouble-makers. Can’t rule things out, obviously, but the likelihood is skewed toward the fishes.
The CFS forecast above shows things starting to become – generally – more favorable around the August 1st. And that holds through August 22nd. That would also mean we would fly through the peak of hurricane season with more suppression, and then re-fire things as we move toward the beginning of October.
WANT TO KNOW MORE ABOUT THE MJO? CHECK THIS OUT!
And, honestly, I think that is a reasonable scenario given the available data. An active Aug 1-21, a bit of a break through Sept 20th, then things pick back up again through the middle of October. With “a bit of a break” meaning that storms aren’t on a blitzkrieg, but rather here and there – if at all.
But before you start canceling vacation plans and putting up your shutters – MJO forecasts are not particularly great. And just because you get favorable conditions doesn’t mean systems will form. So there is a lot of wiggle room.
Instead, I think this is a good time to take the next two weeks and double check your Hurricane Kit, double check your Hurricane Plan, and make sure you have everything you need going into the heart of hurricane season.
Thank you Nick !!! The Pinebelt appreciates you !