Winter's Not Done

A dynamic and potentially disruptive stretch of weather is unfolding across the United States, starting today along the West Coast. While the first system arriving now is relatively modest, it’s just the beginning of a much larger weather pattern that will bring widespread impacts nationwide throughout the week.

Storm Brings Rain and Mountain Snow to the West

A low-pressure system is currently moving into Northern California and Oregon, delivering light to moderate precipitation across much of the western U.S. Expect rain in lower elevations and snow across higher terrain, particularly in parts of the Cascades and Sierra Nevada mountains.

At this stage, precipitation totals are expected to remain relatively light. However, this system is far from finished.

The Storm Will Spread Across the U.S.

As the storm pushes eastward over the next few days—crossing the Rocky Mountains and into the Great Plains—it will intensify further. This strengthening is fueled by a unique atmospheric setup involving a split jet stream.

Moisture from two major sources will combine:

• Tropical Pacific moisture via the “Pineapple Express”
• Warm, humid air flowing north from the Gulf of Mexico

This combination will significantly enhance precipitation across a large portion of the country, especially across the Central U.S. and into the Great Lakes Region.

Despite the influx of moisture, limited cold air will reduce the likelihood of widespread heavy snowfall. Instead, much of the precipitation—even in some higher elevations—will fall as rain or hail.

A broad swath of the northern United States will experience unsettled, late-season winter weather. As the system continues eastward toward the Great Lakes later in the week, the risk of severe weather—including strong thunderstorms—will increase.

A Second Stronger Storm Is Targeting the Pacific Northwest

Close behind the first system, a more powerful storm is developing in the Gulf of Alaska and is expected to slam into the Pacific Northwest late tonight through Wednesday. The heaviest impacts are forecast for Washington, Oregon, and southern British Columbia. Although this second system will weaken as it moves inland, it will reinforce active weather across the northern U.S.

Unlike the first storm, this second system will usher in colder air, leading to a considerable drop in temperatures. This will also increase the chances for accumulating snow across northern states later in the week.

With multiple storm systems and changing conditions expected, it’s important to stay informed. Be sure to monitor updates from the National Weather Service and local forecasts to track how these systems will affect your area.