Seasonal outlook calls for cooler than normal, but it's a tossup on snow.
Chris Anderson walked under the bridge this week as his crew winterized the Grays Bay dam by installing stop logs to form a temporary dam to protect the actual dam’s gates from winter ice damage at Lake Minnetonka’s east end.
Minnesotans might need a few more logs on the fire this winter.
Below-normal temperatures are likely for the state for December, January and February, the national Climate Prediction Center (CPC) indicated Thursday in its outlook for "meteorological" winter. And while the outlook is noncommittal on precipitation, officials indicated winter might bring some drought relief to Minnesota and the Dakotas.
The outlook is far from bulletproof, however. Because El Niño, a global weather influence that had been mounting in late summer, will instead take the winter off, the new outlook is based on shorter-term and less reliable dynamics, said Jake Crouch of the National Oceanic and Atmospheric Administration's Climate Data Center.
Jon Gottschalk, meteorologist with the CPC, described the outlook as "one of the most challenging we've faced in several years."
Even normal temperatures might feel extreme compared with last winter, which was the fourth-warmest on record in the Twin Cities. But Jeff Johnson, chief science officer for Telvent DTN, a Burnsville-based private forecaster, noted that the outlook actually continues a cooling trend already in place. October ended a 16-month streak of above-normal Twin Cities temperatures, and Johnson said the current balmy spell should end after Thanksgiving.
Even so, because the rest of 2012 has been so warm, the year has a 90 percent chance of ending as the warmest on record across the U.S., Crouch said. Through October, the average U.S. temperature for the year was 1.1 degree above the previous record, and 3.4 above the average. Minnesota is one of 21 states experiencing its warmest year on record so far.
Wrong in a good way?
A year ago, the CPC indicated winter across the northern plains was likely to be snowy and cold, inspiring dread in many Minnesotans who recalled the previous winter, when both Minneapolis and St. Paul had record numbers of snow parking emergencies.
Instead, the winter was shockingly warm and dry. For the Twin Cities, the average monthly temperatures during meteorological winter are 18.7 in December, 13.1 in January and 20.1 in February, and snowfall is 36.4 inches. Last winter, those months brought temps of 27.8, 23.3 and 27.7, and only 18 inches of snow.
Crouch said last winter's outlook didn't stand up because it assumed that a La Niña condition -- the alternate to El Niño -- that had been in place would persist. Instead, it faded, leaving the eastern half of the U.S. in thrall to the more changeable North Atlantic Oscillation.
Last year, the oscillation was in a "positive" phase, allowing the jet stream to carry mild, Pacific air across the country. This year, in a negative phase, it will force a kink in the jet stream that will tend to bring cold, dry Canadian air down across Minnesota.
Snow in spots
Cool and dry suggests a winter of blue skies, but Johnson said the winter storms that Minnesotans remember are likely to return.
"I don't see the entire winter being dominated by the colder air," he said. "There may be thaws, and freezing rain and drizzle. But there may be more variability to the pattern as opposed to just staying completely chilly through the entire winter."
Similarly, snowstorms are likely to be spotty rather than widespread and consistent, he said. "The only way we'd end up seeing more [than average] snow is if the vast majority of systems that come through just happen to be in the right spot."
Another forecasting authority, "The Old Farmer's Almanac," foresees a warmer-than-normal winter for Minnesota and the northern plains, with a particularly warm January and roughly normal precipitation. But the Almanac is famous for being more specific than that. It's predicting snow and cold for the days leading up to Thanksgiving, virtually the opposite of what the National Weather Service is forecasting.
Bill McAuliffe • 612-673-7646