A powerful atmospheric river is forecast for Northern California this week, with a bomb cyclone bringing heavy rain and high winds to parts of the Central Valley and Bay Area.

A freeze warning is in effect in Stockton from Monday to Tuesday, Accuweather reports. The AR weather system will bring persistent rain for several days, with the potential to flood roads, small streams and even larger rivers, Fox reported.

The fall clash of the seasons will be evident across the U.S. this week as a mix of severe storms, wintry weather and wild temperature swings make for an active spell of weather for millions of Americans ahead of the Thanksgiving travel rush.

In California, forecasters warned of a hard freeze for much of the Central Valley on Monday evening: “Frost and freezing conditions could kill crops and other sensitive vegetation and possibly damage unprotected outdoor pipes,” the weather service in Sacramento said.

What is a bomb cyclone?

A bomb cyclone, which forms through a process known as bombogenesis, is a severe winter storm.

Essentially, it is a “winter hurricane,” a bomb cyclone that forms when a storm rapidly intensifies and the central barometric pressure drops by at least 24 millibars within 24 hours. The lower a storm’s pressure, the higher its intensity, reports The Weather Channel.

Many of the most intense winter storms to batter the country’s coasts have been bomb cyclones.

NHS also monitors tropical disturbances in the Pacific Ocean

The National Hurricane Center also said Monday it is monitoring an area of ​​low pressure more than 1,000 miles southwest of the southern tip of the Baja California Peninsula that is producing “disorganized showers and thunderstorms.”

Forecasters say environmental conditions appear conducive to the gradual development of this system, and that a tropical depression will form “likely within the next few days” as the system moves westward or west-northwestward over the western part of the eastern Pacific basin .

The hurricane center gives this system a 60% chance of formation over the next seven days.

Additionally, the NHC said a low-pressure system could develop hundreds of miles southwest of the southern tip of the Baja California Peninsula within a day or two.

Some slow development of this system is possible afterward as the system moves slowly west-northwest, according to forecasters, with the system having a 20% chance of formation over the next seven days.

What is a Winter Storm Warning and Warning?

The National Weather Service uses specific alerts to warn of impending severe winter weather: A Winter Storm Watch is issued by the weather service when there is “a chance of significant and dangerous winter weather within 48 hours.” This does not mean that significant and dangerous winter weather will occur – it just means that it is possible.

However, a Winter Storm Warning is issued when “a significant combination of hazardous winter weather occurs or threatens.”

USA Today contributed to this report.

This article originally appeared in The Record: Atmospheric River brings a bomb cyclone to California this week