It will be a warmer and wetter fall, but a colder, snowier winter, according to the National Weather Service's Climate Prediction Center.
The outlook calls for fall temperatures to average above normal from September through November, with rainfall also above the long-term average. The report said trends and historical data suggest the northern Red River Valley and Devils Lake Basin will see the higher amounts of precipitation, especially in October and November.
"Seventy percent of the time, they depict the average conditions accurately," said Mark Ewens, meteorologist with the weather service office in Grand Forks.
"The intent is to show the general area where heavier precipitation is most likely, based on history. In that case, this model works very well."
The CPC said a rapid transition from El Niño to La Niña appears to be well under way. This rapid change in sea surface temperatures in the tropical Pacific Ocean is a significant factor in the CPC's forecasts. The preliminary outlook for December through February is based on the assumption that La Niña will indeed be established, meaning the Northern Plains will see a higher threat of above-normal precipitation.
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"The general outlook is that should La Niña develop as expected, it will be colder than normal," Ewens said. "We'll know more when we take a look at the Pacific in another three months."
Ewens said temperatures should be milder through August, with rainfall more scattered. Fall temperatures will be 2 to 3 degrees above normal and September will start drier, Ewens said, with conditions turning stormy in late October and early November.
Last fall, an El Niño was predicted, meaning milder temperatures and below normal precipitation. Yet, residents may choose to remember only the 25.1 inches of snow from Blizzard Alvin over the Christmas holiday. That storm and two other systems in January accounted for about 35 of the 40 total inches of snow Grand Forks received all winter.
Ewens said the reason was an intra-seasonal wave called arctic oscillation, which modulates weather in the Northern Plains.
"That blizzard was such a freak kind of event," Ewens said. "Arctic oscillation drove or provided the cold air typically missing during El Niño, which had so much moisture at that time, and that's unusual for El Niño."
So, what are the odds of a repeat of Blizzard Alvin this Christmas?
"Pretty slim," Ewens said. "But I've learned in 36 years to never say never because it will come back and bite you."
Reach Johnson at (701) 780-1262; (800) 477-6572, ext. 262; or send e-mail to jjohnson2@gfherald.com .
