We actually have quite a bit to track, for the first time in a while. If you haven’t seen Jake’s outlook from yesterday, I would highly recommend giving it a read to put this season in perspective. It has been incredibly quiet this season, as we haven’t even seen the ‘D’ storm yet (Danielle).
So, since the last post, there have been 2 new designated ‘Invests’, or areas of Investigation. 92L, which is located on a frontal boundary in the North Atlantic, and 91L, which is a tropical wave approaching the Caribbean.
In addition, we have 2 un-named areas to watch, one of which is currently over South America, and one which is currently over Africa. The African one is a very strong tropical wave. You can see, based on the amount of deep storms, that this is a particularly strong wave. It is still 10+ days from the Caribbean, but it’s something to look at for sure.
The satellite shows some of the systems better than the others. 91L and the African storm are very evident, the South American system is just widespread storms, and the 92L is just a weak swirl at this time.
91L is the one that is drawing the most attention right now, and for good reason. The NHC has upgraded the probability of formation up to 70-percent over the next 5 days.
Meanwhile, the other 3 storms all have 20-percent chances of formation over the next 5 days.
Please be very careful when finding information on these! 91L, as well as the storm over South America, have had a lot of buzz from model data, but it’s important to note that they are not tropical depressions yet! The South American one hasn’t even formed yet!
I’ll repeat it: We are NOT expecting a hurricane strike on the Mainland US. The ensemble guidance doesn’t support this, but people love to share scary model runs. Please, try and block out the noise.
With that, let’s look at some of the guidance.
This first map is showing the current analysis of the Atlantic Basin at 850 mb. This is a good indication of low level circulations, and finding things that might develop.
Right off the bat, the circulation for 91L in the Central Atlantic looks way too strong. One of the problems with model guidance is that sometimes it gets things wrong right from the start. I’m writing this last night, so things may change, but it looks like the GFS is possibly too strong right now.
Looking ahead into Wednesday, the GFS shows 3 out of those 4 storms developing, which isn’t exactly likely, so to speak. This run of the GFS has a very strong feature moving off the coast of Africa, and a compact circulation forming off of the Yucutan Peninsula as well. Notice that 91L actually weakens quite a bit, which is certainly possible as well.
The new update to the GFS is far more prone to “false alarms”, so we really have to take this with a grain of salt.
I think the GFS ensembles shows us a more clear picture: We are likely going to see increasing development into next week, but we can’t worry about how strong things are right now.
Just looking at the models, it appears that the African Tropical Wave may end up being the strongest, and fastest developing of the waves, though this one is not likely to impact land any time soon.
We are generally much more concerned about 91L and the South American wave, since the location is climatologically more favorable to impact the US.
This is the GEFS track forecast for 91L. What does this tell us? Not much, honestly. This tells us that there may or may not be a tropical system of undetermined strength between the Leeward Islands and Bermuda. We don’t really have much to look at right now, which is why we have to defer on any impacts for the time being. We can, however, look at the environment and see how the future is looking.
Anddddddd right off the bat, we see one of the biggest problems-one of the main problems this season has seen. Lots and lots of dry air. None of these storms are going to be free of dry air, with a few exceptions. Large-scale high pressure is forcing air to warm up and dry out over the North Atlantic, and that may prove to be detrimental to the tropical systems we’re looking at.
Now, there are a few ways that storms could survive.
First of all, the storm that might move through the Caribbean and the Gulf, is in a much more humid area. This area is going to be more conducive to development, at least with this respect.
The African Wave is currently in a moist environment, but it is going to dry out over the next few days. If it can really organize now, then it’s possible that it can form a bubble of moist air around it, and keep the dry air outside of the center, at least for a little bit.
Based on the current organization of the system, this looks possible, but not likely by any means. That could just be one way we see a named storm out in the deep tropics.
The shear is also pretty strong across most of the Atlantic, with the exception of the Gulf of Mexico.
This upper level wind shear will also help to keep the storms at bay.
Looking at the Ocean Heat Content, which is a way to visualize the depth of the warm water…woof. There is a LOT of heat content in the Caribbean and in the Gulf, flowing around the loop current. Any amount of OHC is good for tropical cyclone genesis, but seeing those high values do raise some alarm bells.
Are we expecting a bad storm in the Gulf?
Absolutely not. But we do have to be honest, and say that if a storm were to enter the Gulf, it has a lot of good stuff to work with. Maximums in heat content and humidity, with a shear minimum tells us that this area might be favorable.
But we do not have a storm entering the Gulf. That part is important!
With upper level winds blowing away from the US Gulf Coast, it also seems like our area isn’t really under a big threat right now. Things could change, but it looks like the 500 mb ridge should set up along the Gulf Coast pretty nicely. If the storm strengthens, and the clouds get taller, then it might get caught in Northerly winds aloft, pushing the storm even further South.
This isn’t great for Mexico, but could be a reason to breathe easy for the US Gulf.
My job is to look beyond the NHC forecast, but ultimately, that is the most important thing. So please, just focus on their advisories. All of this is still very early, and dependent on storm development. Now is time to prepare, but not worry. This is my last tropical briefing, but keep checking back with this site, and always follow the NHC guidance for official information. Stay safe everyone!
