I have another question... When is it that the bombardment of saharan dust and dry air towards the caribbean is supposed to stop??
i don't know.
it is typical that it get's sent over from africa(the SAL) right on time for the beginning of the season when storms start to form on the far east, out of tropical waves sent by the far eastern Monsum rains towards africa, crossing the central african continent and hitting the tropical atlantic waters, sometimes converting under certain circumstances into the well known strong so called Cape Verde Hurricanes, the big ones of the Atlantic Hurricanes.
that peak time of the year for those tropical waves form Africa, runs around mid august til late september.
the actually present dry air content in the mid atmosphere is something different to the Saharan Air Layer/Sahara Sand(named short SAL).
the mid atmosphere dries or moistures due many different other circumstances/occurances playing tiogether.
this year, for the now running peak time of african waves, the mid atmosphere is very dry and stable, a factor which is against development of storms.
such does not mean they can't form, but it means they form less likely, slower, less strong and last less long of a time frame, than they would under more favorable conditions.
as seen on hurricane Danny.
despite the odds against a Storm, it formed up and for some hours even reach Mayor Hurricane Status as a Cat 3 Hurricane with 100knots of sustained windspeeds.
but it had to size down a lot on diameter to get moving, did not last long on it's high powers, and then went down quickly to nothing.
the same tropical wave/Disturbance, which Danny came out of, under favorable conditions, would have been a Mayor Hurricane of even higher windforces and several times the size/diameter, unvulnerable to windhsear or dry air influences from the outside for days, so the same small thingy we just observed for a week would have been a exceptional monster.
if it also would have walked the same direction, is an other theme, as big storms get their steering/directioons from different steering patterns/winds than smaller weak systems do.
Mike