I find a little thermal at 1,700' north of the prisons. This is
what it looked like:

The wind was 22 mph out of the east. I was in the thermal until I go just north
of where I have marked the thermal on this map. Going to the east side of the
thermal I get 500 to 600 fpm down.

This is David's track log:

He finds strong lift to the west, downwind of where I first find the lift. David
came into the thermal right at my altitude, and then I lost him. He was to the
west slightly and zoomed right up.

I knew the wind direction at the time, although not it's strength. I should have
searched downwind, instead of upwind.