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Capital Weather Gang

North America is flooded in warmth and there is no sign of real winter

By
November 10, 2016 at 3:43 p.m. EST
Temperature difference from normal over the Northern Hemisphere, Nov. 10, 2016. ( <a href="http://cci-reanalyzer.org">Climate Reanalyzer</a> , Climate Change Institute, University of Maine, USA.)

North America is awash in warmth and there are no immediate signs of significant winterlike weather on the horizon.

The United States experienced its third-warmest October on record, and warmth has continued through the first third of November.

This fall has been so warm, some cities are setting records for latest first freeze

North America’s most astonishing warmth this week has focused in Canada, where temperatures have been up to 30 degrees warmer than normal.

“On Wednesday, Winnipeg blasted through a 93-year-old weather record,” reported the Winnipeg Free Press. “Environment Canada recorded 25 other places in Manitoba that basked in warmth, toppling records like dominoes.”

In McCreary, about 150 miles northwest of Winnipeg, the mercury rose to 72 degrees (22 Celsius), obliterating the previous record of 52 (11 Celsius), the Winnipeg Free Press added.

Vancouver set a record high just two days before CBC News reported, and said much of British Columbia had been “extraordinarily warm” in November.

Many areas of Canada which normally have snow at this time of year have bare ground.

As Canada is the source region for cold air over the Lower 48, it’s no surprise snow is lacking there as well.

Snow covers a mere 0.4 percent of the Lower 48 states — the smallest area on record for Nov. 10 (dating to 2003).  On average, about 10 percent of the nation has snow on the ground as of this date.

The pattern keeping away the cold is an exceptional one. A strong jet stream from the north Pacific Ocean is roaring across Canada, blocking Arctic air from penetrating southward.

A massive area of high pressure has developed south of the jet stream over interior Canada and ballooned southward over much of the central United States. The intensity of this high-pressure cell is about three standard deviations from normal, or expected to occur just 0.3 percent of the time (assuming a normal distribution).

The pattern has perplexed long-range forecasters, who can’t say for certain when it will break.

Capital Weather Gang long-range forecasting specialist Matt Rogers thinks the mild pattern will linger over North America for another two weeks, at least, and is reluctant to predict when it might change. “It seems like we have to wait it out until next week to get a better sense as to when it’s going to shift,” he said.

Rogers believes the pattern is a hangover from last winter’s record-challenging El Niño event. El Niños tend to feature a strong, northern-displaced jet stream which keeps cold away from North America. Following the big El Niño winters of 1982-1983 and 1997-1998, similar jet stream patterns set up the following fall long after El Niño was over.

In this video, NOAA explains how scientists track El Niño and La Niña weather patterns. (Video: NOAA)

This fall, not only has El Niño ended but NOAA announced Thursday that La Niña has arrived.

Rogers said La Niña should help to slow the global wind down, which would make it easier for the jet stream to buckle and allow cold air to finally spill over North America.

It’s a question of when.