The red areas are dry, the blue areas are wet. The blue blob in the upper right corner is AL90, an “invest” area that will probably not develop (NHC gives it a 10% chance). See the red swath between it and the Caribbean and US? That is very dry air. It will literally suck the life out of the system and kill off any chance of development. This time of year the powerful “Cape Verde” storms that come off the coast of Africa just don’t have much of a chance to develop with all that dry air out there. The Caribbean is “wet” enough for storm to form, but surface pressures are high (you need a low for a storm), and conditions are not otherwise favorable.