Due to mountains (nearly 8,000') close by, winds can be quite unpredictable at Manley, and even more so at Sangster. I have seen winds 180 degrees opposite directions at 15 kts, at each end of runway at Sangster.
At night, some wierd catabatic effects occur at both airports.
Anytime there is a northerly wind component at Manley, look out for turbulence.
I have seen a B-707 (BOAC) bounce 50' after being ambushed by shear at Manley.
I bet JM pilots could tell some tales.