Jay Honeck wrote:
...

Our local AWOS was calling the wind 180 at 13, gusts to 21 -- ...

As we passed through 500 feet AGL, we experienced some moderate turbulence,
followed by some really "hinky" air -- you know, the kind that lifts first
one wing sharply, then the other? ...snip...
Then, the most amazing thing happened. Our ground speed, which had been an
anemic 90 knots or so climbing out in a shallow "cruise climb", suddenly
accelerated sharply. Within seconds, we were doing 130 knots climbing on
the SAME HEADING that had given us a headwind just moments earlier!

Interestingly, the air instantly became silky-smooth, with hand's off flight
producing an absolutely rock-solid heading. As we leveled off at 5500
feet, our ground speed rapidly climbed through 170 knots, meaning that we
had a solid 30 knot tailwind, heading South. ...snip...

You were just a victim of a rather strong high to the south, and an
extremely deep low in Quebec (968 mb, or so). If the air was as laminar
as some posters suggest, then the effect of ground friction is much
enhanced, and you get that "light southwest" wind at the surface,
backing and strengthening significantly above 3000 feet.

The pressure gradient on the weather charts easily supports the winds
you experienced.