Can you Stealth after combat has started?

[TorresGlitch]

Chemlak wrote:

Concealment of the target negates sneak attacks (total concealment for unchained rogue). So that's no to smoke, mist, and fog.

not what we are debating about. There are several ways of getting around that like Oracles' revelations.

Chemlak wrote:

And you have not shown that stealth makes you visually undetectable which is a requirement for invisibility.

I have never claimed so, you've misunderstood and you are wrong.

Stealth doesn't grant invisibility nor does it make you invisible. But while you use it, you become a surprise element as enemies aren't aware of you or your location.
Wordlawyer:
The requirement for being invisible (not invisibility) is being visually undetectable. Stealth doesn't grant you that, but smoke etc will. What stealth allows you to do is move about without the enemies seeing/sensing where you move.

Ex. Assume a mist spell where the enemy saw you cast it.
He knows you were standing there and can with hearing and sense of smell etc locate your exact location (pinpoint your location) but if he doesn't have these tools or something disrupts them, then you can move about without them understanding where you move. (which may allow you to completely dodge arrows and badly placed AoE spells.)

Chemlak wrote:

For the record, I absolutely agree that attacking from stealth denies Dex, but I don't pretend it's RAW.

I don't think it's RAW that stealth grants it but the circumstances around stealth will grant it. And it will grant it 100% of the time since the circumstances (smoke, invisibility etc) always go hand in hand with stealth.

There is 1 way of staying 'not visible' with the stealth skill even without concealment, cover or the like (but for a short period of time);
Stealth Skill
"Breaking Stealth: When you start your turn using Stealth, you can leave cover or concealment and remain unobserved as long as you succeed at a Stealth check and end your turn in cover or concealment. Your Stealth immediately ends after you make an attack roll, whether or not the attack is successful (except when sniping as noted below).

Sniping: If you've already successfully used Stealth at least 10 feet from your target, you can make one ranged attack and then immediately use Stealth again. You take a –20 penalty on your Stealth check to maintain your obscured location."
Source: Stealth Skill

I consider these words to be synonymous 'unobserved', 'not detected', 'hidden', 'unnoticed' and 'invisible'. They are alike but on a case by case basis different. But for the stealth skill's purposes I consider them alike as some people in the know-how expressed considering similarities between a few of the game-terms concerning stealth, 'hidden' and 'unaware'.

Sorry about coming off as pompous :)

[Byakko]

TorresGlitch, I'll admit it does strike me as a little pompous how you have copy and pasted huge sections of the rules as if it's novel information which we haven't already carefully read. A person who has read our posts should have been able to tell that we've gone over the rules quite thoroughly, and are discussing the things it -doesn't- say.

Anyway:

The "big problem" is that a character who is stealthed is in a nebulous "unseen but not invisible state", which is never really fully described in the rules.

Somehow a creature in stealth is both undetected (denying their foe's dexterity bonus to AC) yet not invisible (they gain none of the usual perks of invisibility). This distinction should have been more clearly spelled out and described, imho.

On top of this, it's not even -cleanly- stated that a person caught by a stealthy attacker looses their dexterity bonus in the first place. While this can be argued for based on the description of AC, this loss of dexterity is never given an official term enabling it to be referenced elsewhere.

This issue is especially obvious when you look at abilities like Uncanny Dodge, which most of believe works against a foe attacking from stealth. Yet the ability never actually states this.

[Bill Dunn]

Byakko wrote:

Somehow a creature in stealth is both undetected (denying their foe's dexterity bonus to AC) yet not invisible (they gain none of the usual perks of invisibility). This distinction should have been more clearly spelled out and described, imho.

They're not using an invisibility power, but that may be different from having the invisibility condition. If you can accept that being successfully stealthy renders the PC visibly undetectable (at least for the Perception rolls he's beaten), then everything falls into place.