Lindsay Lohan -- 12 Hours to Dodge Arrest Warrant

Prosecutors will seek an arrest warrant for Lindsay Lohan ... if she's not ensconced at Morningside Recovery by sunrise ... law enforcement sources tell TMZ.

As we reported, Lindsay rolled up to Morningside Recovery this morning ... but she never got out of her SUV. The whip inexplicably left the premises with Lindsay still inside, and she never came back.

Now, law enforcement sources tell us, if Lindsay isn't at Morningside by dawn tomorrow -- roughly 6am in L.A. at this time of year -- prosecutors will go to court first thing in the morning and seek a warrant for her arrest.

It's unclear where Lindsay is at the moment ... but she better get a move on.