December 20, 2012 | Vol. 116 -- No. 35

Mother Nature has tossed us a weather change-up

Predicted drier El Nino weather pattern ‘vanished’ a while ago so wetter, whiter winter predicted

By PAUL DELANEY

Paul Delaney
A early blanket of snow covers Eastern Washington University’s Roos Field Nov. 9.

Staff Reporter

The 1970’s advertisement for Chiffon margarine told us “It’s not nice to fool Mother Nature.”

But it’s perfectly okay as we know for the favor to be returned as she threw weather watchers a nifty change-up over the past couple of months.

“I’ve never in my life seen a warm sea surface temperature pattern disappear so fast,” Eastern Washington geography and meteorology professor Dr. Robert Quinn said back in October when the forecasted El Nino vanished. “It’s gone,” the noted expert in long-term weather forecasting said.

An El Nino is a weather pattern featuring warmer than normal sea surface temperatures and for the Northwest it generally results in lower than normal snowfall.

The last El Nino in the winter of 2009-10 produced just 13.3 inches of snow, fourth lowest since record keeping began in the late part of the 19th century. That came after back-to-back La Nina winters, 2007-08 and 2008-09 that produced respective snow totals of 92.6 and 97.8, the latter an all-time record.

It was sandwiched between another pair of La Nina’s – a colder than normal sea surface temperature pattern ­– in 2010-11 that produced 68 inches of snow and last year’s below-normal 36.8 inches. Normal snowfall on the West Plains, recorded at Spokane International Airport, ranges between 40-50 inches.

Forecasters, including Quinn, had predicted as far back at early summer the formation of a weak El Nino. “So in two months, it went from weakening to, kaboom, this month it’s virtually gone,” he said.

What remains is some warm water in the Central Equatorial Pacific along the coast of Peru and out to about 110-dgrees, west longitude.

“It’s now been replaced by colder than normal water which of course is more of a La Nina pattern,” Quinn said. But it’s not a full version so the new trend will be the middle-of-the-road La Nada, as Quinn calls it.

Since the El Nino pattern has gone away Quinn now focuses attention to the North Pacific, specifically the Gulf of Alaska, which will be our weather-making machine for the next few months. It’s a cold over warm water pattern.

That favors a West Coast trough of low pressure and a wetter Pacific storm track – cold and snowy on occasion – but often a large over water trajectory.

“So basically my forecast is we’re going to see a wet winter, a lot of snow in the mountains,” Quinn said. There will be a mixture of rain and snow in the lowlands, particularly early in the season in November and December.

Quinn’s short long-term forecast, delivered the end of October, appears pretty spot-on. November produced 3.24 inches of liquid precipitation, including .84 inches Nov. 19.

Winter officially begins Friday, Dec. 21, but we’ve had hints of it, as usual, throughout the fall. And that, Quinn said, was predicted. Spokane International has recorded slightly over 15 inches of snow already, up from the 14 and change that fell through the same period last year

Quinn sees things backing off a little on the precipitation side, come January. “I’m not going to say dry, but less wet.”

What caused the sudden demise of the El Nino that had been seen as the primary winter weather maker for 2012-13?

“Good question,” Quinn said. “Normally once those sea surface temperatures get established in the Equatorial Pacific they tend to have a good solid, at least, six month survival.”

The probable explanation is a huge semi-permanent high-pressure system off the coast of South America. It creates the coldest current on earth, Quinn said of the Peru or Humbolt Current. “It comes from the Antarctic regions along the West Coast of South America.”

“Every once in a while that current will really strengthen and when it strengthens in brings a lot more cold water to the Eastern Equatorial Pacific: La Nina,” Quinn said.

When the current weakens and retracts back to the south then the Equator does what it wants to do normally, warm up. “It’s not that simple but you get a sequence of events that leads (back) to an El Nino,” Quinn said.

“So my guess is suddenly that high (pressure) just strengthened and the Humbolt Current just blasted in and literally within about a month wiped out the warm sea surface temperatures,” Quinn explained.

But, he said, that is just his hunch after having studied and taught about weather for nearly 50 years and there is no true scientific confirmation supporting it.

Mother Nature still keeps many secrets hidden from us.

Paul Delaney can be reached at pdelaney@cheneyfreepress.com.

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