Billy Davies was sacked on Monday morning and the experienced Warnock was quickly installed as the favourite to replace the Scot.
That was given more credence when Forest announced they had signed Leeds defender Lee Peltier - the man Warnock took to Elland Road and made captain during his time there.
Reports soon circulated, however, that the Peltier move had broken down and, while that has yet to be confirmed, Warnock's decision not to move to the City Ground has.
Speaking to The Independent the 65-year-old said: "I did not feel the conditions of the job were right for me to manage. I wish them well for the rest of the season."
Warnock's decision is sure to concern the Forest fans, who on Monday afternoon were told to be patient by chairman and owner Fawaz Al Hasawi.
Al Hasawi has revealed that academy manager Gary Brazil will take charge of first-team affairs until a permanent appointment is made, starting with Tuesday night's game against Charlton at the City Ground.
"I would like to place on record my gratitude to Billy Davies for all his efforts as manager of Nottingham Forest Football Club. I wish him all the best for the future," Al Hasawi said in a statement via the club's official website.
"I am aware many people expect me to announce a new manager imminently, however I must stress the need for patience as I make the important decision of who takes the reins at this crucial stage of the season.
"As always I will keep our supporters informed of any developments but in the meantime I ask everyone to get behind our academy manager Gary Brazil as he takes charge of first-team affairs until a permanent appointment is made.
"Gary has carried out some terrific work with our younger players and I am delighted he has agreed to take temporary charge."
Davies' second spell in charge came to an end after a dismal run of form and a breakdown in his relationship with Al Hasawi.
Saturday's 5-0 defeat to east midlands rivals Derby saw Forest's run without a win reach eight matches - a streak which has seen the Reds go out of the FA Cup to Sky Bet League One side Sheffield United and drop out of the Sky Bet Championship play-off places.
Upon his return to the club in February 2013, Davies took the decision to bar most of the media - apart from the official website and a regional TV station.
Al Hasawi has lifted this ban and added: "Supporters can rest assured the local and national press will have regular access to whoever is appointed as our new manager as, with immediate effect, any bans imposed on members of the media are lifted.
"I hope the club can now look forward to enjoying a positive relationship with the press."
Davies, who earlier this season signed a contract extension until the summer of 2017, steered Forest to the play-offs twice during his first spell in charge before his relationship with then-owner Nigel Doughty broke down and led to his departure.
On his return to the City Ground, Davies transformed Forest from mid-table also-rans to Championship play-off contenders in the remaining months of the season. But the Reds missed out on a top-six spot after a final-day home defeat to Leicester.
Before that game, Davies took the unusual step of conducting his post-match press conference.
It was a sign of what was to come in a series of strange goings-on at the club.
This season has seen the media ban and the filming of journalists at press conferences.
Long-serving staff were sacked without explanation while Jim Price, Davies' cousin and his agent, joined Forest's ranks in a senior post, despite failing the relevant 'fit and proper person' tests due to being suspended from his profession as a solicitor.
There have also been stories of rows with photographers at games - namely at Millwall, Brighton and Barnsley.
Through it all, Davies had received the backing of Al Hasawi but a recent disagreement over transfers combined with Saturday's humiliating loss at Derby seems to have been the final straw for the chairman and owner.
Meanwhile, the Football Association announced on Monday evening that Davies had lost his appeal against a three-match touchline ban and will have to serve the suspension at his next club.
Davies has already served a two-match ban after admitting one charge of misconduct for using abusive language towards referee Anthony Taylor after the 2-2 draw with Leicester at the City Ground on February 19.
However, his appeal against the ruling that he deliberately made contact with Taylor in the tunnel was rejected on Monday.
The FA confirmed in a statement: "The FA is aware of a statement issued by Nottingham Forest today in relation to the club terminating their employment of Davies as manager. Therefore, his three-match touchline ban will be stayed until such time as Davies commences employment at a new club.