The climatically obsessed no doubt would love a precise gauge of TV weathercasters' prophetic abilities. Just how outrageously far off the mark were those highs and lows? How frequently did the sun brightly shine when torrents were promised? How many inches of snow actually fell (and fell and fell) when we were confidently assured of a light dusting? So wildly and -- isn't it ironic? -- predictably off the mark are meterologists, it sometimes seems they might better rely on a hard squint at the horizon, a finger held daintily aloft in the wind or the throbbing of a balky knee than the fancy gadgetry they deploy at such expense and with such empty authority. But, honestly, do we expect them to be right? Of course not -- they're scientists (of a sort), not soothsayers, and however rigorous their methods and advanced their technological means, they're ultimately just offering up a best guess. No, what most of us look for in a TV weatherperson isn't 100 percent accuracy but a soothing affability. Sure, we expect a baseline level of predictive competence -- they shouldn't always be wrong -- but a comforting persona is more valuable in the long term. Especially in times of meteorological stress -- when sweating through a prolonged heat wave, sneaking a peek through the basement window at sickly-green tornado skies or shoveling out from under an ass-deep snowfall -- we want a calm voice, a reassuring presence. A guy like KTVI (Channel 2)'s Dave Murray. Murray clearly knows his jet streams, high-pressure systems and dewpoints -- hey, he boasts the American Meteorological Society's seal of approval -- and he was the town's first degree- toting forecaster back in 1976, permanently wresting the weather report from the feeble hands of former clowns and kid-show sidekicks. But it's his warm, self- effacing, increasingly avuncular manner that makes him St. Louis' best: We trust Dave. We've even forgiven him that mid-'80s defection to Good Morning America and later flirtation with WBZ in Boston; Dave, after all, came back. And now, with pert Trish Brown finally off the radar screen, Dave Murray serves as our brightest beacon in the storm.