I sure hope Cliff Mass was right when he declared on his blog yesterday, “We are about to enter an historic heat wave for our region. One day, your grandchildren will ask you… did you really experience the temperatures of July 29th, 2009? What was it like? How did you survive it?”

Not that I or my tomatoes welcome hundred-degree days any more than the next webfoot. I just hope Mass, the ubiquitous UW meteorologist, is right when he says this heat wave is a one-off that future generations will regard as exceptional. More likely, if it’s remembered at all, it will be as a “historic” harbinger of heat to come. Mass and his colleagues’ own high-powered computer simulation of future Northwest climate forecasts mountain temperatures rising ten degrees or more by 2090, a “catastrophic” loss of live-giving snowpack, and “many more hot days in summer”—three times as many days in the 90s, and presumably a commensurate number topping 100.

Not that Mass’s model is infallible. As a PowerPoint presentation by Mass acknowledged, it overestimated the influence of cold winter blasts from the interior, thanks to faulty national models of Rockies topography. And it, along with other climate models, predicted cooler, wetter springs, thanks to increasing evaporation from the warming seas, which would produce more cloud cover. The latest global models show that low-lying clouds—a key planetary protection—will actually dissipate with warming.

I’ve long wondered why Mass never seemed to mention climate prospects in his weekly weather chats on KUOW’s Weekday; he just called anything hot and bright in the offing “another nice day.” Perhaps this heat wave will temper his enthusiasm.

So do you think this is the big one we’ll remember, or just a warm-up?

If you’re hot as hell and just can’t take it any more, you can join other suffering Seattleites tweeting at the weather on the meltocalypse, heatwave, and angryseattle pages.