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Wacky start to Alaska winter confounds weather forecasters

  • Author: Craig Medred
  • Updated: September 27, 2016
  • Published December 30, 2011

Colder and drier weather is ahead for south coastal Alaska, according to the U.S. Climate Prediction Center. That's the forecasters' story, and they're sticking to it despite the bumps of October, November and December when the center also predicted colder and drier for the northeastern rim of the Gulf of Alaska. And then....

Well, the October prediction was right on for precipitation, but way off on temperature. Anchorage saw 1.7 inches of precipitation, a little below the long-term average of 2 inches for the month. But the monthly average temperature of 36.8 degrees was a full 2 degrees higher than the long-term mean.

A 2-degree shift in temperature, as anyone who has followed the global-warming debate knows, is huge. One advocacy group claims a "2°F warming causes a $4.1 billion/year loss, a 1.3% reduction of the total regional agricultural output'' -- just in the states of Missouri, Iowa, Nebraska and Kansas."

So everyone should probably be thankful the center got the temperature prediction right for November to help average out what happened in October. The average temperature for November 2011 in Anchorage was 14 degrees, a finger-numbing, nose-frosting 8.2 degrees below the average. Brrrrrrrrr.

But the precipitation prediction? Wrong again by a long shot.

A holiday nightmare for some, a skiing wonderland for others

November brought Anchorage 2.32 inches of water, double the mean. And because of chilly temperatures, the water came down as snow. Lots and lots of snow -- some 32.4 inches, nearly three feet, had fallen by month's end. Skiers were ecstatic. The snowfall was close to the record 38.8 inches that fell in 1994, and within a tenth of an inch of edging out 1956 as the second snowiest November in Anchorage climate history. Anchorage ended the month cloaked in white. Alaska's largest city looked like a Winter Wonderland heading into the Christmas season.

Forget that.

December came roaring in like some sort of holiday nightmare. High winds toppled trees and tore the roofs off homes. Temperatures skyrocketed. Rain fell heavily. "Air temperatures rose into the lower 50s on the east side of town," the local office of the National Weather Service reported. "Keep in mind that typical max temperatures for this time of year are in the teens and lower 20s."

November snow that wasn't blown away, washed away. Conditions were so otherworldly that meteorologists John Papineau and Emily Niebuhr wrote up a special report about the month's weather. Its title? "Windy, Wet and Wild -- December 2011."

Predictions of colder, drier weather were washed away by all the precipitation. "More remarkable was the copious amounts of rain that was embedded within the storm system," the unimpassioned meteorologists observed. "The majority of rain, on the order of several inches, fell on the Hillside, with much lighter amounts in west Anchorage."

But the rain was only the half the story as a series of four warm storms swept across Southcentral. Wind was the bigger half.

(The) Dec. 3-4 event was notable for the 118 mph wind gust at Glen Alps which is about as high as any since the wind sensor has been installed," Papineau and Niebuhr reported. "Early on the morning of the 4th, the winds in the exit region of Turnagain Arm were the highest reported in the short history of this wind sensor: sustained winds were on the order of 80 mph, with a peak gust in the 90 mph range. This was also the time that the pressure field over northern Cook Inlet weakened and the winds from Turnagain Arm moved into south and west Anchorage. At Ted Stevens International Airport, sustained winds during this period were on the order of 30 mph, with gusts from 55-60 mph.

Hurricane-force winds are not associated with cold, dry weather. Warm waters are needed to create the energy to generate such winds. For reasons unknown, Southcentral Alaska got smacked with the energy of warm, North Pacific waters in December.

Eventually, though, the winds stopped. Temperatures cooled, and a big dump of snow arrived to deliver a white Christmas to Alaska's largest city and the surrounding area. Still, the month is likely to end up warmer than normal -- and certainly wetter. The average precipitation for Anchorage in December is 1.1 inches with an average 15.3 inches of snow. With a couple days left in the month, Anchorage was above normal for precipitation and about two feet above average for snow. And it wasn't the only city trying to dig out. Big swaths of the state received snow above the norm.

Colder and drier? Not so much.

So what does this all mean for the months ahead? Who knows? Papineau is confident the climate modelers Outside wouldn't be predicting colder and drier unless they had some good indicators.

"Their current outlooks are still calling for cooler than normal temps through May," he said. "Additionally, they are calling for below-normal precip as well,'' he noted in an email. "This is odd for them to make any forecast for precip. They tend to shy away from it unless their models are giving a strong signal."

La Nina giving the cold shoulder

The biggest signal out there at the moment is La Nina, the cold-shouldered twin of El Nino. El Nino sends warm currents east across the Pacific Ocean to collide with the North American continent and then deflect to the north. La Nina does much the same, only it sends a cold current. This is supposed to be a La Nina-dominated winter along the West Coast of the U.S. and in Alaska.

"If you list the past 17 La Nina winter temperatures for Anchorage,'' Papineau said, "they are all over the place. However, the statistical mean does indicate a below-normal temp, dominated a by a few very cold events."

Temperatures all over the place? A few very cold events? Hey, it sounds like Anchorage, where the temperature on Friday was 4 degrees, a dozen degrees below the monthly average with the region poised for a January icebox. The forecast called for zero to 10 below on New Year's Eve. Temperatures in the Interior of the state have already turned brutally cold. The weather service reported minus-51 in Tanana on the Yukon River and Huslia on the Koyukok River, with temperatures near that elsewhere.

Maybe that colder and drier is finally on the way.

Papineau said he did go back through weather service records to see if he could find a year with big snows in November followed by warm storms in December to see if there might be some clues to the future. There wasn't. Meteorologists today are very good at figuring out what happened, but predicting what will happen remains far more challenging.

"I have no idea why the patterns for November and December set-up the way they did," he said. "Nothing that I have looked at so far sheds any light on the matter, but further analysis once all of the climate indicators are in may reveal something. In short I have no clue what is going to happen in January-March, as I have nothing to base a forecast or educated guess on."

Which is an Alaska forecasters way of saying, "expect four more months of winter.'' Maybe a warm winter, maybe a cold winter. Maybe a snowy winter, maybe a not-so-snowy winter. But winter for sure.

You can count on it being cold and dark. And even if it's only moderately cold -- say 30 or 40 degrees -- it will still be dark, because even if you can't count on the weather in coastal Alaska you can count on the sun and the earth. The planet tips toward and away from the sun on a set schedule every year.

Take comfort in that predictability, because the atmosphere that swirls around the planet remains unpredictable.

Contact Craig Medred at craig(at)alaskadispatch.com

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