My wakeup HR was 46, and I felt pretty good when I stretched and started my run. The shade temperature was 50 (F). My first mile was a comfortable 12:30 pace. I expected my body to pick up the pace as it warmed up, but it never did. I ran my 2 1/2 hours at approximately a 12:30 pace, although the return was slightly slower; I still had half a mile when my 2 1/2 hours expired, and I walked that half mile back to my car.
It was sprinkling when I left, but half an hour later the rain had stopped. The sky was overcast, and it was nice to run with no direct sun. I did sweat a lot, though, and my hat was pretty wet. Not many people were on the parkway. I only saw one other runner, 4 or 5 walkers, and one cyclist.