Questions I never thought I'd need to know the answer to.

I shot a buck this morning, right through the right shoulder blade. I'm quite confident I penetrated deep as about 8" of a 29.5" arrow had broken off and half of that was bloody. So as I searched and as the day has gone on, my first bow kill seems to have slipped from my grasp.

So after this experience, how long is it safe to let a deer lay before the meat goes bad? Now I know this varies with temperature... and with the number of yotes for an overnight siesta. Today it's in the low 70's... how long would you think the meat is good for? How would you know if the meat was no longer good?

...all questions I never thought I'd need to know the answer to.

well sorry to hear this, next there are a few guys on here that have tracking dogs, I would try to find one, a dog is a great tool of you can get one

as for meat going bad, well there hide works both ways to protect against heat and cold, so in 70 degree's, I would say it could last several hrs after its DEAD, I say dead, as it could be still alive for many hrs , from being shot, or days before a SO SO hit actually kills them,
I would judge how stiff it is once found, they get stiff in a few hrs and well, how bloated it is, and then HOW it smells when you open it up
they will boat a lot faster in HOT/warmer weather

best of luck to you

Sorry to hear you lost this deer but as we all know stuff like this can happen.You say you hit the front shoulder blade.I once hit a deer the same way many years ago.That front shoulder blade is a tough area to hit,very hard to penetrate, and depending on the angle of the shot your arrow may not have penetrated the body cavity area.When it happened to me the deer was slightly angling away from me(only slightly)and when the arrow hit that tough shoulder blade bone it deflected and partially exited out.The deer then ran through the thick brush and a branch or tree caught the arrow and snapped it off about 8 inches back from the broadhead.I did find a blood trail but it ran out after about 200 yds.The deer probably lived but i'll never know.Just my guess.As for the meat,it wont last long in this type of temperature and if the deer does die and lay on the warm ground it will go bad fast.Sorry I cant give you more optimism but as I said this is only my guess.Good luck and I hope I'm wrong.