Yesterday morning broke bright and clear over Manhattan, but not even the worst blizzard would have ruined the outlook for Fred Silverman, the resident wizard at the American Broadcasting Co., whose television series "Roots" had just completed a phenomenal run the night before.

"Everyone is delighted,' the networks 39-year-old entertainment division president said with obvious understatement as he awaited the results of ratings that may make Sunday night's final segment the most-watched program in TV history.

In addition to the ratings already scored - the third episode, aired last Tuesday night, was the third most widely viewed TV show ever - there were strong indications that the series had provoked widespread comment on all social levels across the nation.

Even more impressive was the report that not one of ABC's 190 primary or 10 secondary affiliates had refused to carry the program, which will not be seen again before at least next year.

That meant that the dramatization of Alex Haley's best-selling novel - which traces seven generations of his ancestors from Africa through slavery in the American South to eventual freedom during Reconstruction years - was seen in those Southern states where emotions could be expected to be the most sensitive.

"I know there are some people who have argued that 'Roots' cast all the blacks in a good light and all the whites in a bad one," Silverman said in a telephone interview, "but I wouldn't say so. If you saw the last couple of installments, you know that just isn't true. Some people were evaluating an entire novel on the basis of the first three or four chapters.

"I don't think that kind of criticism is valid. I liken it to going to a Broadway play and leaving after Act I and then doing a review on the entire play. If you take a look at the entire piece, you'll see it was not all black-and-white and was really a superb piece of material. To the best of my knowledge, it was an accurate depiction of the period it covered."

Singled out for criticism was a review by Richard Schnickel in Time magazine entitled "Mandingo for the Middle Brow," that Silverman described as "disgraceful" and as an example of "yellow journalism."

"I have reason to believe he just didn't look at the show . . ." the executive said. "Everybody has a right to his opinion.But I think that was a vitriolic review, and I would expect it from Time magazine."

Contacted at his office later in the day, Schnickel said that contrary to Silverman's assertion, he had actually seen 10 of the 12 hours, but had only seen the first four hours before writing his review because "that's apparently all that ABC had ready."

"The entire dramatization was trash melodrama and degrading to what should have been a seriously-taken historical and psychological study," the critic said. "Surely he doesn't see that because, being a television executive, he has no daily contact with anything that any of the rest of us of any general culture would regard as first-class drama. If you live in the trash business, how do you recognize drama? It's an absolutely fifth-rate piece of work.

Despite that relatively minor displeasure, Silverman - who joined ABC in May, 1975, after 13 years of outstanding personal success at the Columbia Broadcasting System - seemed to accept the series' success far more calmly than some colleagues and observers who had predicted the eight-night-in-a-row format would die in mid-stream.

"The nature of the material was such that if you look at the 12 hours in a reasonably short period of time, it packs a tremendous emotional wallop," he said, explaining why he decided to take the innovative gamble. "To schedule it over a period of eight or 10 weeks would have dissipated the emotional impact."

Giving the "lion's share" of the credit for the creative development of the show to Brandon Stoddard, the network's California-based vice president of dramatic programs, Silverman said matter-of-factly that he was not surprised that viewers committed themselves to the series for eight consecutive evenings.

"We divided it up the way we did because we looked at the schedule, then at the show, and the two things kind of came together," he recalled. "If you don't start off with a good program, though, it doesn't matter how you schedule it."

Whether there will be more series televised on the same consecutive-night basis will be "dictated by the material," Silverman said, but he predicted there would be no spinoff of a regular weekly program as happened with such specials as "Rich Man, Poor Man." Nor, he added, will reruns begin for another year or more.

For Fred Silverman, there were no Monday morning blues. Only blue skies and lots of smiles ahead.