1:25 PM | Tropical activity in the eastern Atlantic

[Latest visible satellite image of the tropical Atlantic Ocean; courtesy Penn State e-wall]

Discussion

All in all, the tropical season so far has been rather quiet in the Atlantic Basin given the frequency of wind shear over the Atlantic Ocean and the steady westward push of dry (Saharan-layer) air off of the west coast of Africa. There is now another tropical wave moving westward in the eastern Atlantic and it should develop into the second named system (Bertha) of the season later this week, but it will face some obstacles in its development in the near term.

[Tuesday analysis of the Saharan Air Layer (SAL) using data from the Meteosat-9 satellite; courtesy University of Wisconsin - CIMSS]

First, this new wave will fight against some rather high wind shear in its vicinity later today and tonight. Varying wind speeds and directions with altitude (i.e., wind shear) is usually an inhibiting factor when it comes to the development of tropical systems. Second, as has been the case quite often this tropical season so far (and last year as well), dry air is pushing westward from western Africa and this wave has to endure more of this Saharan-layer dry air over the next couple of days (yellows, oranges; map courtesy University of Wisconsin - CIMSS). If it should survive the wind shear and dry air - and odds are better than 50/50 - then this tropical wave would likely continue on a west-to-northwest path for the next few days and reach the Antilles Islands region of the eastern Caribbean Sea by the weekend and then the Bahama Islands region by early next week. A second tropical wave follows close behind currently churning westward just off the west coast of Africa, but it is way too early to tell if that system will ever strengthen into a named storm.