While officials at the National Weather Service say they can’t predict with certainty how much snow will fall this winter, they’re pretty sure temperatures will be colder than normal.
How much colder? It’s hard to say, really.
“We can say with 40 percent confidence that temperatures will be lower than usual,” said Rick Fritsch, a forecaster with the Service’s Juneau office. “In climate terms, that’s pretty confident. What I haven’t said is how much colder it will be.”
The average temperature for Wrangell, based only on data from between 1991 and 2010 for the three winter months, is 33.9 degrees in December, 31.3 degrees in January and 34.5 degrees in February. Climate data collected far to the south undergirds their confidence, Fritsch said.
“We have two key factors we use to assess the climate,” he said. “The El Nino southern oscillation (also known as La Nina) and the Pacific Decadal Oscillation.”
This year’s La Nina is neutral, while the Pacific Decadal Oscillation – generally trends in the Gulf of Alaska, which vary on average every ten years – is in a cooler cycle, Fritsch said.
Weather watchers expecting another edition of the 2006-07 snow season, which broke snowfall records across Southeast, will be disappointed, Fritsch said. That year, heavy snowfall was driven during the spring and autumn months, Fritsch added.
“What happened in between was pretty mediocre,” he said. “We had very cold dry air in place on the surface.”
While cooler temperatures would generally indicate more snowfall, occasional tropical storms – known colloquially as “pineapple expresses” can bring warmer moist air up from equatorial regions, resulting in more rain than snow, Fritsch said.
The Service’s forecast for this weekend calls mostly for rain, with highs in the low and mid-30s and temperatures dropping down to freezing at night, with a little snow possible but not much accumulation expected, service forecasters said.
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