COLUMBUS, Ohio (WCMH) — Now that we have entered the realm of meteorological winter, marking the coldest three months of the year (December-February), it is time to start looking more intently for trends or guidance regarding the upcoming season.

NOAA’s Climate Prediction Center updated prediction for December calls for below-average temperatures over the Ohio Valley, and much colder than normal weather in the northern Plains. Milder-than-average temperatures are expected across the Southern states.

December temperature outlook. (NOAA)

Precipitation (rain and snow) is projected to run above normal in December in the Ohio Valley and Mid-South, and much wetter than average in a swath of the West, which is good news for drought-stricken areas that experienced another devastating wildfire season. Drier-than-normal conditions are likely in the Midwest and parts of the Southeast.

December precipitation outlook. (NOAA)

Triple-Dip La Niña

This winter will be the third consecutive La Niña season, a cooler-than-normal sea surface temperature cycle in the eastern equatorial Pacific Ocean that influences the jet stream (storm track) and weather across North America.

A rare three-peat La Niña favors generally mild, dry winters in the southern part of the country, while arctic chill will be primarily limited to the northern tier of states.

The Ohio Valley typically falls in the middle: short-duration blasts of frigid air that follow an active storm track across the region, though many events will feature rain or mixed precipitation. Significant snow normally falls about 100-200 miles northwest of the path of low pressure.

A wild card is whether a lobe of the polar vortex sags south at some point, which is determined by the presence of high-latitude blocking high pressure in the North Atlantic.

Mild Early December

Indications for the beginning of December suggest relatively mild weather (highs in the 40s/low 50s and morning lows in the 20s/30s), with an active Pacific storm track combining with a southern branch in the jet stream to bring periods of wet weather.

There are model signals for a wintry stretch during the week beginning around Dec. 12, with some snow possible, then moderating coniditions leading up to the Christmas holiday.

Acorns, Animals and Almanacs

For time immemorial, people have searched for clues in nature for hints regarding the severity or mildness of the upcoming winter. As a result, some animals and plants have gained notoriety as weather predictors.

Naturalists point out that we are mostly seeing a reflection of early spring conditions when it comes to large number of acorns tumbling from oak trees (mast seasons). A preceding mild winter favors more generous spring flowers that increase acorn development.

The woolly bear caterpillar is also a part of the winter weather lore, based on the width of black bands (cold) vs. wider brown stripes (mild). Here again, the coloration is largely a function of the recent environment and genetics, rather than serving as a predictor of the type of winter to come.

There are several farmer’s almanacs that often differ in their montly and weekly predictions for the winter ahead. Proprietary forecast techniques are primarily based on a blend of solar activity, climate systems such as La Niña and its warm counterpart El Niño, past similar autumn patterns, and other factors.

Large-scale climate systems are analyzed by meteorologists in both the private and public sectors, who also incorporate features such as autumn snow cover in Eurasia and across northern Canada, and air pressure fluctuations in the North Atlantic in winter that favor blocking and cold air intrusions in the eastern U.S.