News

Global stew

la nina

How La Nina might affect Alaska

An ocean circulation phenomenon known as La Nina is brewing in the tropics west of Central America, and the National Oceanic and Atmospheric Administration (NOAA) suspects it might, maybe, kinda, could bring Alaska a colder than normal winter.

Welcome to what we really know about the complex puzzle of how global climate actually works. On the micro scale, some things are predictable. So, too, on the macro scale.

By those measures, science has made big advances over the decades.

Satellites can now track hurricanes from above and thus provide a pretty good idea of where they are about to make landfall. And a global band of weather stations can pretty accurately measure the rising temperature of the planet. 

Between those two extremes, in the real world of what the weather will be like a week from now, a month from now or six months from now, everyone is still guessing. The experts might be making more educated guesses than the average woman in the street, but they’re guessing.

When AccuWeather.com announced last year it was going to start making 90-day forecasts, meteorologists across the country protested what they saw as a climate fraud.

“Forecasts of this type beyond 7-10 days (at the most) are simply not possible,” wrote meteorologist Dan Satterfield. “If someone tells you otherwise, they’re wrong, because we are in the realm of palm reading and horoscopes here, not science. I agree completely with Jason Samenow from the Capital Weather Gang at the Washington Post ‘[AccuWeather] is simply peddling a useless product to people who don’t know better.’ These forecasts are actually even worse than the Farmer’s Almanac, since they give rain chances and temperatures for exact points months into the future.”

NOAA is very careful to make clear its long-range outlook for the winter is just a guess with varying degrees of probability. The federal agency is at the moment predicting an “approximately 55-60 percent” chance – something just better than a flip of the coin – that it’s right about La Nina.

Many moving parts

“There’s a variability factor that stands out,” John Walsh, the chief scientists for the International Arctic Research Center at the University of Alaska, said Thursday.

Actually there are a bunch of variables: sea surface temperatures in the North Pacific and Bering Seas, atmospheric forcing on these temperatures, the affects of diminished sea ice on the North American side of the Arctic Ocean ice, and big questions as to whether that developing La Nina actually develops.

Dave Tolleris, a former National Weather Service forecaster, who now runs a company called WXRisk.com providing tailored weather forecast for businesses, is more blunt than Walsh.

“…If you are desperate to find out what the winter weather pattern is going to look like and you are trying to get an early preview so you can get yourself all hyped up, I would suggest you take a Valium because any early winter forecast being made now through the end of October is probably going to be worthless crap,”  he says on the WXRisk Facebook page.

“….Any seasonal forecast for the winter that is based upon La Nina right now is based upon a projection of an event which is still developing. This makes any EARLY winter forecast very difficult. For example the American CFS (coupled forecast system) model shows a moderate La Nina in place by January but most of the other climate models including the European and the Japanese show a weak La Nina in place. This obviously has major implications for the overall winter patterns over the central and eastern portions of the country (and, of course, Alaska).”

Worthless crap though the forecast might be, NOAA’s suggestion of a possible winter chill from La Nina, the girl, versus the warmth of El Nino, Spanish for the “boy Christ-child” and so named for its climatic appearance off Ecuador and Peru around Christmas time, has set off a bit of a buzz in the 49th state where residents have endured a string of long, dark winters short on that bright white stuff important for snowmachining, skiing and dog mushing.

The Iditarod Trail Sled Dog Race – Alaska’s biggest winter sporting event – moved its restart, the real start, north of the Alaska Range to Fairbanks because of lack of snow in 2015, beat its way across a snow-short Range in 2016, and moved the race north again to Fairbanks this year. 

Alaska’s lastest, great-global-warming spurt ended, at least temporarily, in December of last year, but it seems a long time since the winter of 2011-2012 when the state’s largest city set a snowfall record of more than 11 feet and shivered into a year (2012) that turned out to be the coldest in 30 years. 

It is worth noting that was a La Nina winter.

Only four years later, Alaska witnessed its warmest year on record. That was an El Nino winter, compounded by global warming and “The Blob.” 

This year is already on track to be a warm one even if things chill out significantly from here on.  Alaska had a top-10 summer no matter how much colder Alaskans might have thought it to be than last year.

Human perceptions of weather-normal change even faster than the weather.

Still warm

As this is written, September 2017 is tracking along much like September 2016, which ended 3.1 degrees above the norm.

The average temperature in Anchorage for Wednesday was 52, a whopping 8 degrees above normal. It is representative of a month in which 22 days have tracked above normal. Daily weather ups downs are the norm, but there has been a warmish pattern to this September.

The coldest of the four days below the norm went only 4 degrees low. On the high side, there have been two days on which the temperature went 8 degrees above the average daily high, five days when it was 5 degrees above the average, and five days when it was 4 degrees above.

Suffice to say that despite all the talk about impending cold, it has been a very warm month. The average date for first frost – Sept. 23 – is well past, and there is no hint of frost in the near future. The forecast lows through the end of the month are predicted to stay several degrees above freezing.

Of course, the weather can change fast in Alaska. The northern latitudes are known for their extremes in variability.  Fort Yukon, Alaska, holds the national record for temperature extremes, going from 78 degrees below zero to 100 degrees above, although not all in one year.

But for comparison, Honomu Mauka on Hawaii’s Big Island has the record for the least change in extremes with a record low of 49 degrees and record high of 84 degrees. That’s a total swing of 35 degrees.

Temperatures swings of 35 degrees or more happen regularly within 24 hour periods in Alaska. On Jan. 10, 2012, the daily temperature in Fairbanks ranged from 21 degrees down to 26 degrees below zero. The daily range of 47 degrees was not extreme enough to even warrant a mention in the monthly climate report for the Central Alaska city. 

Richard James, a senior scientist at Prescient Weather, goes into Fairbanks temperature variabilities at great length on his weather blog when he outlines Fairbanks weather history from the 1930s.

“Readers of this blog may have noticed, as I have, that the 1930’s often show up in comparisons between current and historical weather events in Fairbanks, because many records set in the 1930’s are still standing.  For example, December 1934 saw the greatest winter chinook in Fairbanks history, with high temperatures in the 50s for five consecutive days resulting in a complete snow melt-out and the only brown Christmas in the city’s history,” he writes.

“Of course, there was plenty of very cold weather too in the 1930’s.  If we look at the daily record low temperatures for Fairbanks (1930-present), half of the daily records for cold in December-February were set or tied in the 1930’s (45 out of 91 days). ”

Nineteen-thirty-three was one of the coldest on record in Fairbanks. It was a La Nina winter. 

“The average temperature for 1933 was 22.0 degrees, the lowest on record since complete records began in 1906,” the Fairbanks Daily News-Miner reported. “The lowest was -60 degrees on January 28. There were 164 days when the maximum temperature was freezing or lower, (and) 243 days with minimum temperatures freezing or lower….”

But that was then and this is now. There has been a new normal established since the ’30s. James calculates the growing season in Fairbanks has extended by about 22 days since then with most of the change coming in the fall.

So what’s coming?

Alaska has clearly warmed since the 1930s. The climate has changed. So if it does get colder in the state this winter, it will be colder only relative to the unusual warmth Alaska enjoyed for the past couple winters.

But will it get colder?

Walsh suggests a flip of the coin might tell you.

“We shouldn’t be surprised if there is a cold winter,” he said, but Alaska also shouldn’t be surprised if there is another warm one either because there are so many unknowns.

Officially, NOAA is still calling for above-normal temperatures for Alaska for October, November and December, which are clearly fall months to most of America even if Alaskans tend to think of November and December as part of winter. If that La Nina kicks in, it shouldn’t be until at least January, at least officially.

The national Climate Prediction Center hedges its bet this way:

“As the ENSO (El Nino/Southern Oscillation) becomes more certain during the next couple of months, corresponding adjustments will be made to the seasonal outlooks.”

In other words, don’t invest in those new skates, skis or snowmachine counting on an Alaska winter of old when snow comes early and the temperatures stay cold enough that it sticks around.

Tolleris’s reference to “worthless crap” might be the best summary of what the current La Nina prediction is worth.

Even short term forecasts are pretty unreliable.  A 2009 University of Nebraska study examined forecasts for accuracy.

It picked “the 6-10 day precipitation forecasts issued by the NOAA CPC (Climate Prediction Center) for the contiguous United States. This forecast is identified by farmers and extension agents as the most useful forecast for nearly all farming decisions during the growing season.

“The results from the accuracy analysis show that the forecast has been correct about 40 percent of the time at each location, which is higher than the expected 33 percent correct from a random tercile forecasting.”

Forecasting has only improved since 2009, but you still wouldn’t want to bet your house on it or your journalistic credibility:

Citing the warm, wet weather sometimes associated with El Nino, KTVA-TV two years ago predicted lots of snow for the Thanksgiving weekend start of skiing at the Alyeska Resort east of Anchorage. 

It didn’t happen. Alyeska has since given up on try to opening for Thanksgiving, an old tradition. The resort this year pushed its opening day back to Dec. 15 with owner John Byrne telling the Turnagain Times the weather makes a Thanksgiving date impossible.

“The last five years, we haven’t had the temps to make snow,” he said, “and there hasn’t been enough natural snow to open in November.”

The last La Nina winter was 2011-2012 – six years ago. Alyeska had snow for that Thanksgiving opening, but the 2011 La Nina started developing early.

This one? Who knows. But it’s alway fun to speculate on what MotherNature might deliver.

 

 

 

 

 

 

 

 

 

 

 

 

 

Advertisements

1 reply »

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s