For winter 2017, the Almanac has predicted colder-than-normal temperatures for most of the United States. Here’s a weather update.
By November and December, temperatures at and around the North Pole were rising above freezing, while Siberia shivered through record cold.
The north polar region has been experiencing temperatures some 30 to 50 degrees F above normal, which has kept sea ice formation at record low levels. Meanwhile, temperatures in Siberia have plummeted to –30° to –50° F, shattering their daily cold records by 10 to 20 degrees.
This all ties in with a recent study published in Nature Climate Change by researchers at China’s Lanzhou University, who found that a loss of sea ice in the Arctic regions due to rising temperatures in the Barents–Kara seas, along with an increase in snow cover over Europe and Asia, has caused the polar vortex to weaken.
Polar Vortex Influence
You may recall that the polar vortex was associated with cold air in eastern North America a couple of winters ago. The weakening and shifting of the vortex suggested by the Lanzhou study would block high pressure systems from dominating Earth’s high latitudes, sending them southward and bringing cold temperatures into the eastern and north-central United States.
Other studies have shown that increases in Eurasian and Siberian snow cover in the fall can have similar effects on the polar vortex, bringing cold and snowy weather into the northeastern quarter of the United States.
These studies combine to suggest that the coming winter will be much colder than the past one in the eastern and central portions of North America.
El Niño to a weak La Niña
All of this is consistent with the change from last winter’s strong El Niño to a weak La Niña this fall and winter. Along with the other factors that control our winter weather, this means that nearly all of the country will be colder than last winter, although most places will still have above-normal temperatures when averaged across the entire winter season.
- Snowfall will be above normal from southern New England and western New York southwestward through the Appalachians; from eastern Minnesota eastward to the U.P. (Upper Peninsula) of Michigan and southward to St. Louis, Missouri; and from central North Dakota westward to the Pacific coast, with below-normal snowfall in most other places that normally receive snow.
- Rainfall and precipitation will again be below normal in most of California, which could result in higher food prices next spring and summer.