The GFS model simulates a developing storm system with low pressure over the Plains on Saturday. (

A coast-to-coast storm system is throwing a speed bump in holiday return travel plans, bringing the worst weather of every season to an extensive swath of the Lower 48. Heavy rain and even a tornado already struck Southern California as the storm moved ashore Thursday, with hefty snows and severe weather likely in the central United States during the next few days. Disruptions to air and ground travel are likely in some locations.

The storm first drenched the Pacific coast, with Los Angeles picking up 3.34 inches of rain in five days from back-to-back systems. Meanwhile, a weak tornado moved ashore in Ventura Harbor, Calif., as strong thunderstorms rumbled across parts of the Golden State. In the higher elevations, feet of snow have fallen. And that’s just the beginning.

A meteorological domino effect

The European model captures the domino effect of storms, simulating low pressure reorganizing several times. (

The storm stirring up all the inclement weather is a series of several storms all wrapped up beneath the same surge of cold air and atmospheric spin aloft. Like a row of toppling dominoes, one area of surface low pressure is expected to hand off its energy to the next in the next few days. This relay race of storms is likely to bring a smorgasbord of weather threats from the Southwest to the Upper Midwest and, eventually, to New England.

The first installment of the multi-act atmospheric tango should begin overnight as a zone of low pressure takes shape from northern Chihuahua, Mexico, up through West Texas, eastern New Mexico and into Colorado. This area of storminess should eventually consolidate into an intensifying low pressure center over the High Plains on Saturday morning.

Southwestern U.S. impacts

The European model simulates potential snow through Sunday, with the greatest amounts in the higher elevations of the Southwest and Four Corners region. (

Snow is already falling in the higher elevations of the desert Southwest and the Four Corners region, particularly in northern New Mexico. Winter storm warnings are up for 8 to 12 inches of snowfall possible above 7,500 feet. A few pockets of 12 to 18 inches are possible in the San Juan Mountains of southwest Colorado, where an avalanche watch is also in effect.

In the valleys and lower elevations, a general 3 to 6 inches is likely over a broad area.

Precipitation should wind down abruptly by Saturday morning as the storm intensifies to the east, pulling in drier air from the west.

A Plains snowstorm, severe weather trigger

Rainfall projection from the European model through Sunday. (

As the low ejects from the Rockies into the High Plains, it should quickly intensify. The exact path of the low’s center hasn’t been determined, but the best zone for heavy snow will be on its northwestern flank, whereas the warm sector to the storm’s south and east is likely to spur heavy rain and even severe thunderstorms.

The low is likely to march through Kansas, bringing moderate to heavy rainfall along the Interstate 35 corridor in Oklahoma and Kansas. One to 2 inches of rain is possible throughout this zone. In this “warm sector” of the storm, severe weather is possible for Saturday, with a few tornadoes not out of the question, although the threat of a large-scale tornado outbreak is low. The severe thunderstorm risk extends from Louisiana and Arkansas into the Missouri Ozarks and eastern Oklahoma.

Additional chances at severe weather are possible in the Deep South on Sunday. The place to watch looks to be Mississippi and Alabama, though a severe threat could hit southern Tennessee, as well.

Then there’s the snow. Snow is predicted across most of South Dakota by daybreak Saturday, spreading into northern and western Nebraska during the afternoon as cold air filters into the region amid a tightening temperature battleground beneath the storm. Recent periods of unusually mild air could make it hard for the snow to stick initially.

Potential snowfall through Monday as projected by the European model. (

Snow is then likely to make it to eastern North Dakota and Minnesota on Saturday evening, becoming heavy overnight into Sunday. The long-duration snowstorm is expected to rage in northeastern Nebraska and the Dakotas on Sunday, walloping western and northern Minnesota. Minneapolis proper may dodge the snow, as snow bands pinwheel to the north of the city.

Hourly snowfall rates and timing modeled by the European model. (

A widespread 10 to 12-plus inches is expected for much of northern Nebraska, particularly north of Highways 20 and 275. Similar snowfall amounts are also predicted for a large chunk of the Dakotas and Minnesota. The storm should be accompanied by progressively higher winds as it intensifies, blowing and drifting the snow.

Snow looks to wind down west to east on Monday.

Great Lakes impacts

As that storm system “occludes” and essentially wraps itself up in cold air, it is expected to transfer energy to a new storm center gathering strength to the east, over the Great Lakes. That should set up heavy snows falling over northern Wisconsin and especially Michigan’s Upper Peninsula on Monday.

The American GFS model projects snowfall across the Great Lakes between Sunday and Tuesday. (

This phase of the storm is more difficult to forecast, but indications are that a general 6 to 12 inches will be possible in northern parts of the Great Lakes.

New England forecast

The storm’s third and final act, this time in New England, could come in two rounds.

On Monday, the low over the Great Lakes could bring a narrow ribbon of precipitation into parts of New England, from the New York/Canada border through portions of central New Hampshire and Maine. This is a finicky feature associated with warm air riding north, preceding the main storm. Several inches of snow or a period of mixed precipitation are possible during this time.

Then things become interesting as the storm system — by that point in eastern Ontario and western Quebec — will likely spur yet another new low-pressure center, this time off the New England coast. However, it’s not expected to fully mature before it pulls away, meaning that the Northeast may be hit by both disturbances. This is known as a “double-barreled low” pressure setup.

The GFS model depicts two low pressure centers influencing the Northeast in the Monday/Tuesday time frame, part of the “double-barreled low” structure. (

As such, Tuesday could feature snow for northern New England amounting to several inches as cold air drains south behind the low off the coast of New England.

However, the precipitation won’t all fall in the form of snow. Rain, freezing rain and sleet are all possible, with the potential for significant icing in some areas. The exact forecast details are tough to nail down right now.

A GFS simulation of precipitation type over New England for the Monday and Tuesday storm. Top left is rain, top right is freezing rain, then snow on the bottom left, and finally sleet on bottom right. (