WHAT DOES CLIFF SAY?” tens of thousands of us obsessively asked each other last December. We were in the middle of one of the longest runs of snow in Seattle history, and the pronouncements of local meteorologist Cliff Mass had the urgency of dispatches from a war zone. A week before Christmas, four and a half million people with a zillion errands to run, roads already impassable from the previous storms, garbage uncollected, planes grounded, holiday parties canceled, the few Metro buses that were inching along treacherous emergency routes crammed to capacity—in short, the city essentially paralyzed—and what Cliff was saying on the blog that he had taken to updating two, sometimes three times a day was that “a really threatening event is possible for Saturday night and Sunday. Not a wimpy convergence zone…but a major Pacific weather feature.”

Already famous locally for his popular Atmospheric Science 101 class at the University of Washington and his weekly weather prognostications on KUOW, Mass had been riding higher than ever all that autumn on the strength of his newly published best seller The Weather of the Pacific Northwest. And then the snow started falling and didn’t quit and suddenly Cliff Mass was the indispensable seer to a desperate population. On that ominous morning of December 18, some 30,000 local weather nuts were hunched over computer screens, reading his blog, 25,000 of us clicking back again (and again) to revel in the words major Pacific weather feature.

What our meteorological prophet did not reveal was that while frozen Armageddon was bearing down on us, Mass himself was 3,000 miles away caring for his ailing father in New York. “I could see everything on my laptop,” Mass, trim and fit in his mid-50s from years of biking to work, told me six months later in his office in the UW’s atmospheric sciences building. “These days, with so much information available, there’s no need to be on the scene.”

Mass paused before delivering one of his signature provocative jabs. “The fact is,” he murmured in a Long Island accent undented by three decades in the Northwest, “meteorologists are the last ones who should be allowed to forecast the weather. The weather service guys over at Sand Point tend to overforecast snow because they like it so much. Inevitably judgment is impaired by excitement.”

Mass’s relish in mixing it up with the National Weather Service and his absolute conviction that he is “the preeminent authority on Northwest weather” (to quote the jacket of his book) have made him something of a local meteorological rock star (one television forecaster calls him the Eminem of weather). But the pokes and boasts go beyond bad-boy posturing. As everyone with a professional stake in Pacific Northwest weather will tell you, Cliff Mass and Brad Colman, the meteorologist in charge of the National Weather Service forecast office at Sand Point, have been tangling for years over how best to probe, analyze, predict, and communicate the mysteries of the atmosphere in this damp corner of the world.

NEXT: Predicting weather in a predictably rainy city.