I have seen that same thing happen a lot this time of year over the years, with SW winds. I have some interesting stories regarding paragliding boats and people getting a certain height up.
Not for certain why, but here is my guess.
The water is SO cold... lol... it is chilling the air down at the surface and up a little bit, as well.
The warmer air (the air with wind) passes over this colder air, creating a wedge.
So, I think the wind is unfortunately up above a little higher than our kites. That's why Sam had much better wind with his kite up an extra "mile"
Go inland, and that wedge disappears and the winds blow good.
Just a guess.
