From its beginning, the 2013 Atlantic hurricane season was forecasted to be an above-normal season, but it has turned out to be very quiet—almost historically quiet to this point. The ACE (Accumulated Cyclone Energy) for the 2013 Atlantic Hurricane season thus far has been 29. The highest ACE for a season was the 2005 Atlantic Hurricane season with an ACE of 250, and the lowest ACE for a hurricane season was 17 in 1983. If we were to finish the season with an ACE of 29, that would be the fourth lowest ACE for a season or the fourth lowest tropical activity for a hurricane season.
There have been two main factors for the low tropical activity. The first deals with persistent dry and descending air that has occurred over much of the Atlantic basin this summer. The Insight package's Saharan Air Layer product has routinely shown large areas of dry air and dust moving west across the Atlantic Ocean this summer.
Saharan dust is often associated with descending air, which also prohibits tropical storm formation. These factors have greatly diminished tropical storms that form in the traditional Cape Verde season near the coast of Africa, and those that have developed have often suffered a quick demise due to dry air entrainment. Even though the Cape Verde season is essentially finished, large amounts of Saharan dust continue to move off the African Coast, as evident with the image below.
The second dampening factor has been wind shear. Areas in the Caribbean Sea and Gulf of Mexico have experienced a high amount of wind shear throughout the summer.
Tropical Storm Chantal in the Caribbean and Tropical Storm Karen in the Gulf of Mexico quickly diminished due to high wind shear. In fact, currently the Wind Shear product from the Insight package shows high amounts of wind shear over the entire Gulf of Mexico and the western Caribbean Sea, preventing any potential storms from developing in these areas for the next 5-7 days.
As we look across the entire Atlantic Basin, we see that conditions are very quiet with no tropical disturbances on satellite and a cold front moving across the west central Atlantic.
Additionally, Satellite-Derived Reflectivity from the Insight package provides a view of precipitation where no radars are present.
As we head through the rest of the month of November, chances of another tropical system developing are becoming much less with time.