Snow to grind Christmas travel to a halt in western US; Rain to cause delays in eastern US

By Alex Sosnowski, AccuWeather.com Senior Meteorologist

December 21,2015; 10:33PM,EST

 

 

As millions take to the roads and skies leading up to Christmas, rainstorms will drench the East as snowstorms plunge across the West.
According to the American Automobile Association (AAA), one in three Americans will take a trip during the holiday season with the number of travelers expected to top 100 million for the first time on record.
A large percentage of holiday travelers will encounter weather-related delays this week.

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Two storms will bring extensive warmth, rain and fog to the Eastern states as two storms drop across the Western states with cold air coastal rain and mountain snow.
JUMP TO: Rain, fog and thunderstorms to accompany eastern warmth | Pre-Christmas snow could blanket part of North Central states | Rain, snow to move southward and inland over West

Rain, fog and thunderstorms to accompany eastern warmth
From the Mississippi Valley to the Atlantic coast, the vast majority of holiday travelers will not have to contend with snow or ice. However, delays and difficulties associated with rain and fog are likely, along with the potential for downpours in some locations.
Most people traveling in the East through this weekend can leave the heavy winter outwear at home. In most cases, the coldest air of the month has already occurred. Be sure to pack some waterproof gear.
For those driving, windshield wipers will need to be in good working order. Locally heavy rain is in the offing with the potential for localized flooding. Lower speed will be needed to reduce the chance of hydroplaning.
Downpours and the risk of flooding will greatest in the South.
Two storm systems will sweep northeastward from the South Central states bringing plenty of moisture amid the warmth.

Long stretches of many highway corridors will be affected, including interstates 10, 20, 40, 55, 80, 81, 90 and 95.
The rain will impact Chicago, Detroit, Atlanta, Cincinnati, New Orleans, Nashville, Washington, D.C., Pittsburgh, Philadelphia, New York City, Boston and Charlotte, North Carolina.
The first and weaker of the two storms will cause rain to move quickly northeastward from the Gulf of Mexico to New England, spanning Monday night into Tuesday night.
The second and larger of the two storms will more more slowly and will cause a mosaic of rain and drizzle over much of the eastern half of the nation on Wednesday. The rain will exit the Midwest, but it will continue in the Appalachians for a time and the Atlantic Seaboard much of the day on Christmas Eve.
In addition to rain and fog, thunderstorms could become locally severe in parts of the South on Tuesday and Wednesday. Thunderstorms capable of producing damaging winds and isolated tornadoes will extend from central Texas and southeastern Oklahoma, to Louisiana, Mississippi, Alabama, Arkansas and Tennessee.
Motorists should turn on headlights when driving during rainy and/or foggy conditions, even in the daytime, to increase visibility to other drivers.
People on the road should keep an eye out and be prepared to react safely due to rapidly changing weather conditions.
Pre-Christmas snow could blanket part of North Central states
Snowfall east of the Rockies will be almost non-existent in the days leading up to Christmas.
However, a batch of snow will drift eastward across North Dakota and into northern Minnesota on Tuesday and into Tuesday night.
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Part of I-94 in eastern North Dakota to western Minnesota could become slippery.
There is a chance of a brief period of snow developing farther south and east on Wednesday. Enough chilly air could seep in behind the eastern rain to produce a narrow band of snow from northeastern Kansas to central Wisconsin and part of the Upper Peninsula of Michigan on Wednesday into Wednesday night.
Rain, snow to move southward and inland over West
People traveling by vehicle in the mountains of the West will need to have tire chains on hand. Windshield wipers will get a workout along much of the Pacific coast.
Daily storms will roll in from the Pacific Ocean through Christmas Eve and will largely affect the Interstate-5 corridor of the Northwest, as well as the adjoining major highways including interstates 80, 84 and 90, as well as routes 20 and 299.
The first storm will hit into Tuesday with heavy rain, gusty winds and the risk of flooding from western Washington to northern California. The storm can have major travel implications from Seattle to Portland, Oregon, and Eureka, California. Rain will also press southward to San Francisco and Sacramento, California, with spotty showers dotting the Los Angeles Basin.

Through Tuesday, the first storm will also unload 1-2 feet of snow on the Cascades and the northern and central Sierra, which could result in whiteouts and the potential for stalled travel over the passes from Snoqualmie to Donner.
Snow and low-elevation rain will spread slowly inland to eastern Washington, Oregon, Idaho, northern Nevada, Utah and the western parts of Montana, Wyoming and central Colorado through Wednesday.
The caboose of this recent storm train into the West will arrive on Christmas Eve and will have eyes farther south.
Colder air will also plunge southward with the late-week storm and could bring low snow levels throughout the West Coast states. Not only may travel be difficult over Donner Pass, but roads over Tejon and Cajon passes could become covered with snow.
Rain will likely return to San Francisco and Sacramento. Snow could fall on Salt Lake City into the night of Christmas.
Additional bouts of rain, interior snow and gusty winds will follow as the train of storms continue into the Northwest and Rockies.