Another winter storm to bring heavy snowfall across the US

An intense winter storm will bring heavy snowfall, strong winds, and icy conditions to a large portion of the United States into the coming weekend. Dangerous travel conditions are expected, and drivers are urged to be cautious.

The winter storm, named Decima by Weather.com, will originate from the Gulf of Alaska and will start to affect the US as a southward plunge of the jet stream.

According to the National Weather Service (NWS), the arctic air mass will spread from the northern Plains and Midwest to the Ohio Valley, Mid-Atlantic, and Northeast as a rapid arctic cold front.

High temperatures will be between 11 and 16.7 °C (20 and 30 °F) below average in the north-central US on December 14 and will spread eastward on December 15. The front will likely induce further lake effect snow downwind of the Great Lakes later in the day into December 15 (local time) while an arctic high-pressure field will produce another arctic air blast into the northern High Plains by December 16.

Winter storm warnings have been put in effect in regions between southern Washington and Oregon, Siskiyous, northern California, and parts of Idaho while winter storm watches are in place from the Sierra Nevada, California to parts of Montana, Wyoming, and South Dakota.

The energy of the jet stream is expected to produce a low pressure field over the Plains, and move northeastward trough the central and the eastern US. The moisture associated with the system will meet the cold air from the north and form a high-pressure system over the eastern states. The resulting air mass could produce snowfall, sleet and freezing rain.

Dangerous travel conditions are expected across 1 931 km (1 200 miles) of the central US into the coming weekend. According to the AccuWeather experts, blizzard conditions could affect Denver and Chicago while strong snowfall will likely cause traffic disruptions across the Rockies, Northern Plains, and Upper Midwest.

"Motorists and airline passengers may want to explore an alternate or more southern route as confidence is high that there will be widespread, major travel disruptions with this storm," said Brett Anderson, and AccuWeather Senior Meteorologist.

Major snowfall will be concentrated between central and northern Colorado and Northern Nebraska, South Dakota, northern Iowa, Minnesota, Wisconsin, and central Michigan. The snow may also spread to some areas in the central Plains and the middle Mississippi Valley.

Cold weather conditions, combining snow sleet, and freezing rain, will also affect regions between Northern Kansas and Southern Nebraska to southern Iowa, northern Missouri, Illinois, Indiana, Ohio, and southern Michigan. In the region between the middle Mississippi Valley and the Ohio Valley, a majority of precipitation will be in the form of rain, although the storm may begin and end with wintry precipitation.

Dangerous driving conditions are expected around Chicago from December 15, and in Detroit on December 16. Freezing conditions, resulting from the remnants of rain which will change to snow are anticipated on December 17 in St. Louis. Freezing conditions are also in store for the area west and east across the Ohio Valley and lower Great Lakes on December 17 and 18.

A forecast for pressure system over the US, December 14, 2016. Image credit: NOAA/NWS

A forecast for pressure system over the US, December 15, 2016. Image credit: NOAA/NWS

A forecast for pressure system over the US, December 16, 2016. Image credit: NOAA/NWS

"The snow, ice, and gusty winds anticipated this weekend will likely lead to airline delays and potential cancellations in the major hubs from Denver to Chicago and Detroit. For example, around Denver, the temperature will plummet from the 30s F to below zero from Friday night to Saturday morning. The rapid temperature drop with high winds and heavy snow will create blizzard conditions with major delays likely at Denver International Airport," explained Anderson.

Blizzard may affect areas around Chicago on the night of December 17 (local time). Severe weather wintry conditions are in store for the Carolinas and Maine for the coming weekend. Dangerous travel conditions are expected along the I-81 and the upper part of the I-77 corridor.

Featured image: US weather forecast map for 00:00 UTC on December 17, 2016. Credit: NOAA/NWS