Similar to the days prior to Thanksgiving, the worst weather will focus on the days prior to Christmas as millions of travelers take to the roads and airways.
According to AAA, 94.5 million people will travel 50 miles or more over the holiday season, spanning Dec. 21 to Jan. 1.
Most of the travel troubles will be caused by a single storm system forecast to affect much of the Central and Eastern states on Saturday and Sunday.
The storm this weekend will bring a wide variety of weather ranging from temperature extremes to heavy snow, ice, flooding rain, fog, severe thunderstorms and the potential for tornadoes.
First Things First, Friday Travel Trouble
Prior to the main storm this weekend, snow will slide southward Friday from the Pacific Northwest to part of the Great Basin, northern Rockies and High Plains. A second batch of snow is also forecast to take a similar path in the West Friday night into Saturday, before fizzling out over the central and southern Rockies.
Enough snow will fall from both systems to slow travel along extensive stretches of I-15, I-25, I-84 and I-90 in the United States, as well as Canada Highway 1 in part of British Columbia.
Another dose of snow will sweep inland over the Northwest to the northern Rockies on Monday.
Thousands of miles to the south on Friday, areas of rain and mountain snow can slow travel along I-40 in parts of Arizona and New Mexico.
Thousands of miles to the northeast on Friday, ahead of the massive weekend storm, a swath of snow will streak along the Canada, U.S. border from the Great Lakes to the St. Lawrence Valley, northern Maine and the Maritimes. Up to several inches of snow will fall.
Weekend Snowstorm to Reach Thousands of Miles
The main storm this weekend will begin to put down snow across the northern Texas Panhandle and western Oklahoma on Saturday.
As the storm rolls out, heavy snow will develop later Saturday over central Kansas and will continue along a northeasterly path Saturday night and Sunday through northwestern Missouri, central and southeastern Iowa and Wisconsin, much of northern Michigan and across central Ontario, southern Quebec and northern New Brunswick.
Portions of the central Plains, Upper Midwest and southeastern Canada could be on the receiving end of a foot (30 cm) of snow.
Ice and a wintry mix is also another concern for travelers with the storm from part of central Oklahoma to southern Michigan, southern Ontario, along the St. Lawrence River in Ontario, northern upstate New York, northern New England central and southern New Brunswick. Enough ice can accumulate in part of this area to bring down trees and power lines.
The snow and ice could bring vehicles to a crawl or possibly shut down portions of I-29, I-35, I-70, I-80 and I-90 in the U.S., and highways 2, 20, 40 and 401 in Canada.
Rain, Flooding and Fog
On the southeastern flank of the storm from central and coastal Texas to southern New England, drenching rain will fall.
Some of the rain will be heavy enough to cause flooding.
Episodes of dense fog could also be a player in slowing ground travel and causing flight delays, especially from around the Great Lakes to the Northeast.
Dangerous Thunderstorms, Tornado Risk
Farther south, there is the risk of damaging thunderstorms and tornadoes from parts of central Texas to the southern tip of Indiana Saturday and Saturday night, with the risk of locally severe thunderstorms farther east on Sunday.
Storm, Rain Remnants Reach East Coast
A cold front associated with the storm system will push showers and thunderstorms to the Atlantic Seaboard late in the weekend. Downpours, poor visibility and locally gusty winds could cause travel delays during this time from Boston to New York City, Philadelphia, Washington, D.C., Charlotte and Atlanta Sunday afternoon and evening. Until then, much of the area will bask in record-challenging warmth.
By Monday, most of the direct effects from the storm will diminish, and travel conditions will improve over the Central and Eastern states.
Rain will be restricted to the southern Atlantic Seaboard, and colder air will be sweeping across the Midwest and into the East. Bands of lake-effect snow can cause localized travel problems downwind of the Great Lakes.
Better Travel Conditions by Christmas Eve
In much of the Southwest, the weather will be good for travel, spanning Saturday right through Christmas Day.
Over much of the nation, travel weather for Tuesday and Christmas Day will be good.
Some snow could fall on parts of Colorado on Christmas Day, and rain showers may hug the Atlantic Coast from Florida to North Carolina.