With all of the hype about what an active tropical season we're in for, you might find yourself wondering - Tropical What??? lately. After 2 systems moved through the Gulf in roughly one week (Alex and Tropical Depression 2), it's been relatively quiet for the past few days across the Atlantic Basin.
The above image shows the Sea Surface Temperature (or SST) situation as of late Friday afternoon. The upper image is the observed temperature, and the lower image shows the change in temperature over the previous 5 days. As you can see, Alex and Tropical Depression 2 have taken a toll on the SSTs in the western Gulf of Mexico (note the lighter blue shades on the lower image depicting a decrease in SST over that area).
As a general rule of thumb, tropical systems tend to develop and/or intensify in regions where the SST is (1). warm to begin with and (2) rising. With this in mind, areas of decreasing SST would tend to be less likely to see organized tropical development and/or intensification in the near-term. On the other hand, areas where SSTs are rising would tend to be more favorable for tropical development.
Meanwhile, take a look at the SST change off the coast of west/northwest Africa. A pronounced warming has taken place over the past 5 days in that region. The image below (courtesy of stormpulse.com) shows an impressive looking tropical wave moving off of the African coast at this time. It will be interesting to see if this system taps the increasingly warm, unstable conditions in the region and is able to develop into an organized system.