150 mph is awesome, but Cat 5, which Melissa now is, and may stay until over land, can do sustained 175 mph, and there will likely be gusts. 175 mph is almost half again as destructive as 150 mph (power varies with square of wind speed), and this storm is moving at a snail's pace, so specific locations may experience this kind of wind power for hours. Further, the storm is still gaining strength. All those seaside shantys will simply disappear, and most people who stay in them will die. And then there is the better part of a meter of rain. Over every square meter of landscape. Try to get your head around where all that water can go, and how it can get there. And on top of all that, the storm surge may be measured in meters. The destruction in Jamaica will be unprecedented.