The GFS model showing a tropical cyclone approaching the Lesser Antilles in about five days. How strong it could be remains to be seen.
A tropical wave over the eastern Atlantic continues to move westward without much convection or organization associated with it. Dry air and a general lack of upward motion in the atmosphere are keeping the system in check for now.
Despite the lack of organized thunderstorms, the NHC has increased the potential for development over the next five days to 40%. This is due to the fact that the overall environmental conditions are expected to improve in the favor of gradual development of this system.
So far, there is not a lot of global computer model support for the area. This is not too uncommon over the deep tropics when marginal conditions are in place. The GFS model seems to have the most consistency, showing a gradually developing tropical storm moving towards the Lesser Antilles within a week. Whether or not this actually happens remains to be seen but we are heading in to a more favorable time period and as such, interests in the region should keep an eye on this system.
It will be very interesting to see if this tropical wave actually develops. If it does, considering it is still only late July, then it will show me that the deep tropics are not quite as hostile as we’ve seen in recent weeks and even dating back to last year. The plethora of dry air dominating the tropical Atlantic tends to make me skeptical about any significant development but time will tell, that much is for certain.
In the east Pacific, tropical storm Hernan, which formed yesterday, is gaining strength and could become a hurricane before it moves over cooler water and begins to weaken. It poses no threat to mainland Mexico as its track is away from land.
I will have more here tomorrow morning.
M. Sudduth 2:25 PM ET July 27
Saharan Air Layer
This part of the hurricane season is typically very quiet and for good reason. It is during this portion of the year that we see the strongest of what are called “SAL” outbreaks. SAL stands for Saharan Air Layer and it is a the equivalent to spraying Raid on insects: it kills hurricanes.
The reason is simple. The low to mid level dry air originates from the Sahara and North Africa. Often times the SAL is populated with fine dust and other suspended particles such as sand. This acts to squash any chances of tropical convection and moves generally westward, eventually reaching the Caribbean and even the United States.
During especially strong SAL outbreaks that end up moving in to the Southeast, the result is often an incredible sunset for a few days as the dust filters out just enough sunlight to create a brilliant deep orange to red glow. It is also not uncommon for dust to collect on car windshields.
The good thing about SAL is that it means no hurricanes. With a strong layer of dry, stable air, there is absolutely no chance of development in the tropical Atlantic; not until the environment moistens up. This usually begins to happen around the second week of August. If the SAL outbreaks continue past that time period, then we may start to wonder about whether or not there will be much of a hurricane season left. However, I would bet that this is yet another typical July SAL event and a month from now, we’ll be talking about the potential for development across the same region that is so hostile right now.
Until then, enjoy the quiet, and perhaps the brilliant sunsets, courtesy of SAL.