Found a site called StormCarib.com that has an ap that calculates the closest approach of any storm that you want to put in. I’ve been looking at the data given by the 11.00am bulletin data and some interesting things have emerged.
First the bulletin
T 200 PM EDT...1800Z...THE CENTER OF HURRICANE DEAN WAS LOCATED NEAR LATITUDE 17.1 NORTH...LONGITUDE 76.0 WEST OR ABOUT 80 MILES... 125 KM...SOUTHEAST OF KINGSTON JAMAICA. DEAN IS MOVING WEST-NORTHWEST NEAR 18 MPH...30 KM/HR. A MOTION BETWEEN WEST AND WEST-NORTHWEST IS EXPECTED OVER THE NEXT 24 HOURS. ON THE FORECAST TRACK...THE CENTER OF DEAN WILL BE PASSING VERY NEAR THE SOUTH COAST OF JAMAICA OVER THE NEXT SIX TO TWELVE HOURS. MAXIMUM SUSTAINED WINDS ARE NEAR 145 MPH...230 KM/HR...WITH HIGHER GUSTS. DEAN IS A CATEGORY FOUR HURRICANE ON THE SAFFIR-SIMPSON SCALE. FLUCTUATIONS IN INTENSITY ARE COMMON IN MAJOR HURRICANES AND ARE POSSIBLE DURING THE NEXT 24 HOURS. HURRICANE FORCE WINDS EXTEND OUTWARD UP TO 60 MILES...95 KM...FROM THE CENTER...AND TROPICAL STORM FORCE WINDS EXTEND OUTWARD UP TO 205 MILES...335 KM.
The utility gives the following information:
Results for Kingston, Jamaica (17.93N, 76.78W):
The approximate Closest Point of Approach (CPA) is located near 17.3N, 76.9W or about 40.9 miles (65.9 km) from your location. The estimated time of when the center of the storm will be at that location is in about 8.3 hours (Sunday, August 19 at 7:18PM EDT).
Results for Montego Bay, Jamaica (18.5N, 77.92W):
The approximate Closest Point of Approach (CPA) is located near 17.6N, 78.1W or about 63.5 miles (102.2 km) from your location. The estimated time of when the center of the storm will be at that location is in about 13.5 hours (Monday, August 20 at 0:30AM EDT).
Results for Grand Cayman, Cayman Islands (19.28N, 81.35W):
The approximate Closest Point of Approach (CPA) is located near 18.4N, 81.6W or about 63.7 miles (102.4 km) from your location. The estimated time of when the center of the storm will be at that location is in about 25.3 hours (Monday, August 20 at 12:18PM EDT).
Note that currently hurricane force winds extend outwards 60 miles from the center. So from this information Grand Cayman and MoBay may escape hurricane conditions completely. Kingston is going to get a hurricane, that much is assured. However the may not get the Category 4 winds that would be found around the eyewall.
Now this is the best possible interpretation of this, hurricanes get stronger and weaker and a very marginal shift to the north or south could change this completely. But it is grounds for hope.