It's not quite pulling numbers out of a hat, but it's close here are my thoughts:
I think the current trend of relatively above average SST's will continue for the summer months. Enhancing any storms that make it to hurricane status.. With neutral conditions otherwise, I think we're going to see the following breakdown:
18 Depressions
14 Tropical Storms and 2 Subtropical Storms (16 total)
10 Hurricanes
6 Major Hurricanes

Ok now why these numbers?
let's look at the last few years:
Cat 04 03 02 01 00
TS 15 16 13 15 15
HC 09 07 04 09 08

So I'm fully expecting about the same TS/ST development. I'm also expecting anything that gets going will have a generally neutral development but with warm SST's will still be able to ramp up to a minimal hurricane (ergo, the high number of hurricanes projected). I also expect the hurricanes to have enough warm ocean water to reach major hurricane status about half the time. So, it'll be busy, I really expect to see one Subtropical storm at the start of the season and one at the end of the season. That's also symptomatic of both warmer SST's in colder weather, leading to hybrid/transitional systems, as well as better understanding and diagnosis of when a storm is a Subtropical system. My gut is also telling me that 6 Major hurricanes seems high, but Last year there was 5, and it seems viable to have one more.

Take care and I'll be wishcasting for all fishspinners and a lot of fireworks but no damage.

-Mark