Meteorologists differ on how much the weather is changing

The day before Christmas, Mount Bachelor was desperate for precipitation.

Six feet of snow later, euphoric skiers were plowing through the powder, and the line of vacationers anxious to shell out $45 for day passes stretched for miles.

A similar transformation took place in the Bull Run Watershed, the source of Portland's drinking water.

Typically, Bull Run's two reservoirs are filled by mid-October. This year they didn't fill until mid-November, and an uncharacteristic dry spell in December brought water levels there to dangerous lows.

A few solid rainstorms later, the reservoirs were full and are expected to remain that way through the spring, as usual.

Indeed, even in one of Portland's drier years, the city's water bureau never had to use its backup wells.

A mere 31 inches of rain fell in Portland last year, nearly 6 inches below normal. This came just one year after the end of Oregon's second-driest rain cycle in 100 years, from Oct 1, 2000, through Sept. 30, 2001.

'This was the first time I've seen the 'summer' dry season extend until close to Christmas,' reports KPTV (12) meteorologist Mark Nelsen. 'No one expected two dry years almost back to back.'

But opinions differ about how dire our current climatic position is Ñ and how significantly the region's weather patterns are changing.

While rain and snow levels remain far below average, the city's water supply is doing fine, and the powder on the ski slopes is deep. The recent storms also have provided a sprinkle of hope for the farmers of Eastern Oregon, who have suffered through four droughts in a row and would like to avoid a fifth.

The outlook for simultaneously generating ample electricity and restoring salmon populations, however, is less promising.

Forecasts for the Columbia River Basin call for below-average snowfall, meaning less water running off into the river to turn turbines and help young fish migrate to sea.

Signs of global warming?

It was an unusual fall in Portland, to say the least. A cold, clear Halloween was followed by a bright, clear Thanksgiving Ñ with almost no rain falling in between.

Midway through December, Portland's steady rains still had not arrived.

Even the storms that have since showered Portland and covered up bare spots on the ski slopes have not brought levels back to normal. State climatologist George Taylor says that as far as avoiding drought is concerned, 'things are looking better and better. But we're not quite where we need to be yet.'

Taylor is calling for a wetter than average January and February, which would be welcome news for salmon, skiers and the Bonneville Power Administration, the federal agency that markets power generated by the dams of the Columbia.

Nelsen, by contrast, predicts a drier than average, relatively warm winter, because of the El Nino weather pattern. El Nino years are marked by sharp increases in ocean temperature and, in the Pacific Northwest, dry and mild winters.

That would make snow in Portland unlikely this winter, although as Rob Marciano, chief meteorologist of KATU (2), notes, the city is 'way overdue' for snow.

Nelsen said historic snowfall levels in Portland show a steady decrease from 1880 to the 1950s, when they plummeted. If we go seven more weeks without extreme cold or snow, that would make the fourth consecutive mild winter for Portland Ñ the longest stretch in recorded history.

So does that mean Portland's climate is changing as a result of human-caused pollution, as part of global warming?

Glaciers are melting at alarming rates in Alaska and northern Europe. Scientists predict that within 15 to 20 years, there will be no glaciers in Glacier National Park in Montana.

But studies conclude that global warming should lead to wetter winters in Portland, not drier. So, while increasingly dry summers in the Northwest do match the forecasts of global warming experts, increasingly wet winters do not.

State climatologist Taylor downplays the impact of human activities on global warming. He points out that the glaciers of North America and Europe have been 'shrinking since the last Ice Age,' and the warmest decade in Oregon's last 100 years was the 1930s.

Oregon's coolest decade (temperature-wise) was the 1960s. While the climate has been steadily warming since then, Taylor says, 'The overall trend since the 1930s has actually been a bit downward.'

Still, as meteorologist Matt Zaffino of KGW (8) argues, 'The amount of evidence of human-caused climate change is getting greater and greater. Even though there's a lot of uncertainty in what the ultimate result of human activity will be on climate, we're stacking the deck pretty heavily É . The change may happen quicker than many people think.'

Marciano puts the issue into perspective by looking at the extremely long term: 'We have about 200 years of decent climate data. The Earth has been around for almost 5 billion years. We'd be pretty arrogant to think we know what the climate is going to be like in the next millennium.'

Contact Ben Jacklet at This email address is being protected from spambots. You need JavaScript enabled to view it..

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