Well the interaction of Issac with the mountainous islands along its path has proven to be good, bad, and ugly for the storm. The initial interaction with the southern peninsula of Haiti actually helped the center of circulation consolidate this morning due to the dry air down sloping off the mountains and into the center of Issac. This enhanced the vertical circulation and inturn produced deep convection around a vorticity, becoming the main core of the storm. (the good)
The interaction with Haiti, slowing motion of the storm, and the down sloping winds have been added to the lift inside the core this evening, subduing the deeper convection. Issac will go through some fluctuations in intensity and a gradual reformation of the core once or twice during the passage across the island.
Latest satellite image shows another burst of convection over the core with a distinct mountain shadow due to the winds down the mountains.
The aircraft found a flight level wind of 64 knots, and many measure by dropsonde of 55 knots or better. With that in mind, along with model tracks, NHC has decided to move the storm to the east and intensify the system which will trigger hurricane wording across the keys and south Florida including at least some of Tampa Bay and Melbourne NWS county watch areas.
Be prepared for the worst, and know that the intensity forecast is highly suspect at this time due to the continued interaction with the mountains of Haiti and Cuba.
Turn to your official watch and warning authorities, National Weather Service, and the National Hurricane Center for the latest updates.