The beginning part of the climatological peak (mid-August through September) for the Atlantic Basin tropical season has arrived and, as if right on cue, the tropics are suddenly looking more and more active after a couple of quiet weeks. There are now two disturbances of interest that could develop into named tropical systems over the next several days. The first system is more of an immediate concern and is gradually intensifying over the western part of the Caribbean Sea. This system is likely to cross right over or very near the Yucatan Peninsula over the next day or so and then head right into the Gulf of Mexico where it will encounter generally warmer-than-normal sea surface temperatures. This encounter with warm Gulf waters will combine with diminishing wind shear to likely make for a rather favorable environment for development. Ultimately, this Caribbean system could have an effect along the northern Gulf coast and could even send some moisture up the east coast. Meanwhile, a second area of interest involves a tropical wave that has just moved off the west coast of Africa. This system could intensify over the next several days as it takes a westward trek across the tropical Atlantic Ocean although wind shear could play somewhat of an inhibiting role in the near term.
In addition to the generally warm sea surface temperatures that exist at this stage of the summer, these two systems have a couple of large-scale factors that may support intensification. One is that the dry air intrusion from the African Saharan Desert that has dominated the tropical scene over the eastern Atlantic in recent weeks in an inhibiting manner has seemingly lost some of its punch in recent days. Secondly, the Madden Julian Oscillation (MJO) index that tracks a large-scale tropical disturbance that propagates eastward around the global tropics is moving into an area (“phases 2 and 3”) that typically favors tropical development in the Atlantic Basin.