I wouldn't trust any forecast that is more than maybe three days out. Check our local news afiliates (WFTV, WKMG, WESH and WOFL) when you are closer to your trip. They will be more accurate than national services like weather.com (but even they get it wrong sometimes).
Now that we are out of the "wet" season, our rains come primarily from fronts moving through the area. So the length of the rain event is tied to how fast the front is moving. The winter rains are usually not as heavy as the summer storms, with less wind, but they tend to last longer - sometimes all day, or even a couple days if you get a really slow front. Because they are tied to weather fronts, the forecast is much more changeable based on how fast the front gets here (or if it stalls out and doesn't make it here at all). We just had a drizzly day here on Saturday - no hard rain, but drizzles and light showers most of the day - more "umbrella" weather than "poncho" weather.
For my winter trips to Disney, I usually take a compact umbrella, a larger umbrella, and my nylon poncho. I tend to use the compact umbrella more than anything else.