I would so not worry about it. It says isolated, scattered and only 30%. That is nothing really. Also, the average rain fall for Jamaica in April is about 2.5 INCHES, not a lot at all. You may see a passing shower but that is about all. never fear you will have a great weather and will really enjoy those passing afternoon showers, it is amazing what you can find to do in paradise.
I think this was back on the old MB, but I remember someone posting a picture of a number of folks hanging out in a jacuzzi during a hearty rain. I thought that was so cool, it really looked like they were enjoying themselves. While it doesn't rain a great deal here in Southern California, when it does, it's often a cold one. So a nice, tropical WARM rain may actually serve as an enjoyable experience. Not saying I want it to rain a lot during our vacation, but a daily half hour or so dose ain't gonna kill us and in fact may even be a wee bit o' fun.
Reading is fundamental. It's just that for some, it's more mental than fun.
stop looking at any weather sites!! They ALWAYS list rain for Negril and other areas of Jamaica - that's how tropical climates are reported on. We vacationed at CN in mid-April in 2008 and had beautiful, sunny weather most of the trip. It rained in the afternoons several times during our 7-days, but most only lasted an hour or two and then the sun came back out (and you often get to see some beautiful rainbows afterward too!). It's really nothing to worry about! One of the rains happened while we were heading back from the caves on the cat cruise, so a bunch of us hung out in the garden hot tub during the entire rainfall and it was one of the most fun times we had!! (except for the rain watering down our yummy drinks!!) CN is paradise even in the rain!!
Do NOT be afraid of the rain. My husband and I went to CN during "rainy" season in September. It DID rain every day BUT the rain was always late afternoon. When we would go in to shower and get ready for the night is when it would rain. By the time we were dressed and ready to head out for dinner the rain cloud was gone and the stars were out. Have fun!!!