Here we are again with tomorrow's flops today, courtesy of inveterate (though not infallible) industry analyst Herb Jacobs, who since the dawn of television has spent his summers sizing up the new fall TV season ahead.

In competitive terms, Jacobs sees the three-network derby that kicks off Sept. 27 as the hardest to call in history. "This is the closest ever," he says. Some industry observers think CBS, last year's winner, will win it again, this time by a nose, or maybe a hair, over ABC, but Jacobs, who favors ABC to win, says, "This thing can change the other way by just one show bombing out."

For instance, he notes, if Warner Bros. and CBS can't get Tom Wopat and John Schneider back into the driver's seat of the ol" General Lee on "Dukes of Hazzard" -- and it now looks as if they can't -- that could seriously impair the traditional lead CBS enjoys on Fridays. Fortunes in television ride on ridiculous nonsense like that. In his recently published Forecast -- now being eyeballed by industry insiders -- Jacobs says, "We expect the closest statistical prime-time race in TV history."

If the prospect of a new fall network season sounds hilariously unexciting, it doesn't strike Madison Avenue that way. Despite the fact of a recession-wracked economy, and the widespread agreement that there's nothing revoluntionary or thrilling about the new fall schedules, advertising time has been selling at an absolutely frenetic pace, even on NBC, the third-rated network. Not only that, but each network now has more advertising than ever to sell. By the end of this season, all three will have added an extra minute of commercials to prime time each evening, certainly a curious way of combating the audience erosion that the newtorks have suffered because of pay TV and other video distractions.

The networks will introduce 24 new shows this fall, compared with only 16 introduced in the fall of the 1980-81 season. Dancer Fitzgerald Sample, an ad agency that issues its own fall forecast, says the mortality rate on new shows introduced last fall was 75 percent. Does this mean the public's getting more and more fickle about what it will watch?

"The public isn't fickle," says Jacobs. "I think the public is getting smarter. They's starting to reject these things quicker. And the networks are getting more gun-shy. They pull the shows faster if they don't perform right away. All the networks are now scattershooting instead of shooting with a rifle. They're so gun-shy, they're afraid of themselves. And so they pull shows off even more quickly.

"Anyway," he says with his usual growl, "it's gonna be a tight race."

And it will not lack for flops. Already, NBC has pulled one new show out of the fall lineup, "Mama's Family," a spinoff from sketches on the old "Carol Burnett Show" but without Carol Burnett. NBC removed it from the schedule to put in "Taxi," the super comedy series that ABC dopily dropped last spring. Spokesmen for both NBC and Joe Hamilton productions say that "Mama's Family" is the No. 1 bench-warmer and will be called in to replace the first show to fail on NBC.

Among new shows almost certain to fail, Jacobs sees a CBS sitcom, "Square Pegs," as perhaps the worst of the worst. The pegs of the title are two 14-years-old girls trying to get popular in high school. "How the hell could they even make that?" Jacobs hoots. "It's not a good show. Not the CBS image at all." Of the cast he says (and said, in a speech to the Atlantic Ad Club), "They're unattractive and they're unfunny, but at least they can't act."

Other shows whose stars should probably not make a down payment on a new Mercedes include, according to Jacobs, "The Quest," "Ripley's Believe It or Not" and "Matt Houston" on ABC; "Seven Brides for Seven Brothers" and "Mama Malone" on CBS; and on NBC, "Voyagers," "The Knight Rider" and "Powers of Matthew Star," which was supposed to be one of last season's flops but was postponed when the kid who plays Matthew suffered serious burns in an accident.

Jacobs departs from traditional thinking along Madison Avenue in some of his assessments. The DFS survey sees "Newhart," the new Bob Newhart vehicle on CBS, as having a "good" chance at making it, but Jacobs writes, "We think it will have a hard time keeping its audience awake." As always, Jacobs' summaries of the new shows are mercilessly to the point.

Of "Seven Brides," loosely adapted from the movie musical (recently produced to empty seats on Broadway), Jacobs writes, ""7 Brides Etc." has failed on stage, screen and television [before]; why give the public another chance to turn it down?" Jacobs says ABC's "Star of the Family" features "direction by computer, script by computer and production by the numbers . . . What has happened to creativity?" But a spokesman for the producer of that show says from Hollywood that Jacobs has only seen a tiny portion of the pilot and that it's unfair to make a prediction based on that.

Jacobs is not totally grumpy about the new season. He does see a few hits there, including the CBS "Bring 'Em Back Alive" on Tuesday nights: "A poor man's copy of "Raiders of the Lost Ark" -- but who cares?" He also thinks the new "Odd Couple," with a black Felix and a black Oscar, has a chance, and of course Sally Struthers in "Gloria" on CBS Sunday nights simply can't miss in the ratings, because it is "hammocked" between two huge hits, "Archie Bunker's Place" and "The Jeffersons."

New fall TV seasons may not titillate the public as they once did, but at least the one ahead will start on time; unlike those of the past two years, it has not been delayed by any strikes. And Jacobs' feisty enthusiasm for it all is contagious. After all, he's as excited as ever -- and he'll be 71 this year