Yes, we are in hurricane season. That means that really at any time, even when climatically unfavorable, tropical growth can emerge. Here below, we are actually observing a fairly strong African tropical wave emerging in the eastern tropics of the Atlantic Ocean creating a large area of disorganized thunderstorms. According to the National Hurricane Center, it currently has 10% tropical growth over the next 2 days, with 50% forming over the course of a week.
Take a look at the surroundings over the next few days early next week for wind shear and vertical humidity. Typically, at this time of year, we find the main points of departure and interest still confined to the Caribbean, the Gulf of Mexico and the southwestern Atlantic. We also often have at this time of year a strong subtropical Azores ridge in the Atlantic Ocean that tends to filter dry air into the tropical Atlantic with wind shear; however, we are in somewhat unusual territory due to the extreme heat we are seeing now in the MDR (Main Growth Area) and the lack of shear force.
To illustrate this point, we are indeed in record warm temperature territory of the eastern tropics of the eastern Atlantic, where sea surface temperatures are 1-2 standard deviations above average. often. We see these types of values in late August and early September and statistically, statistically, above the last 30 years average, these temperatures don’t show up until the first week of September! Quite amazing.
Below, we see over the next few days, verbatim, the wave gradually moving westward. Note that there is no harmful wind shear around its circulation (we usually like to see less than ~20 knots to increase intensity). Right below, compare that to the general relative humidity at 700mb when it’s covered in moisture, so we know we have an environment that’s favorable for this wave to form a depression. when there is a possibility to invest this weekend.
Fast-forward to early next week when we’ll watch this disturbance, which could then be a depression, cruise across the central Atlantic. The generalized elevation model would have a large (albeit relatively weak) subtropical Bermuda ridge to the north, with disturbance to its south to the west. By the end of next week, we should see the central subtropical ridge distribute east into the Atlantic, with a trench shifting north into the Atlantic. It was this moment that created the “opening way” for the tropical disturbance to be pulled northward. Now, at this point, we will know specifically whether it becomes as strong as some models are showing (i.e. GFS, EURO) or remains weak. If the first is true, the tornado will “feel” the winds around it, and a stronger tornado can fly higher vertically in the atmosphere as opposed to a weaker system. . The latter will make things more interesting as it can continue towards the Caribbean as it won’t “feel” the prevailing driving flow.
This is reflected in the tornado paths forecasted through the EPS, remember this is a set so we can get a lot of variation by rerunning the model in this case 51 times to see what possible outcomes could be. As we can see, a clear division into two types of tracks is shown based on the differences discussed in terms of the strength of the tornado and what will happen to the steering mechanism next week. There’s still a week to go, so expect a ton of uncertainty and stay away from any wild posts on that social network (especially the GFS wonderland ones!).
For now, we will monitor and follow up in the next few days. NHC will probably consider this an investment, then it will most likely form a tropical depression early next week. We will monitor and update all information, so stay tuned!
About the author
Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands