[Climatological trend for Atlantic Basin hurricanes/tropical storms]
Even though we have now just passed the climatological peak of the Atlantic hurricane season (approximately September 10th), there are reasons to believe that tropical activity can still have a direct impact on the US mainland as we head through the rest of summer and into the fall season. Sea surface temperatures generally are running at above-normal levels for this time of year in much of the Atlantic Basin and this should certainly help in the formation of late season tropical systems.
[Saharan air mass map; courtesy University of Wisconsin/CIMSS]
In fact, there are currently a couple of tropical waves in the Atlantic that are moving generally to the west. Indeed, there is actually a third wave just now coming off the African west coast and it is also headed in a general westward direction. The latest “Saharan air mass” map (courtesy University of Wisconsin/CIMSS) shows the current location of these tropical waves (circled) and it also suggests that these waves may not have to deal with much dry Saharan air in the near future (shown on map with orange, yellow and reds). This has not been the case for much of the summer in that most developing tropical systems during the past few months have encountered dry Saharan air in their path and this factor has inhibited growth in most cases. The bottom line, the warmer-than-normal sea surface temperatures combined with the lack of much in the way of dry Saharan air in the Atlantic Basin, suggests that the tropics will need to be closely monitored as we head towards the fall season.