A spiraling weather system referred to as a bomb cyclone is sitting off the coast of the Pacific Northwest, and its effects will soon be felt in the Yampa Valley.

“It is a rapidly developing low pressure system,” said Mike Weissbluth, a local meteorologist who runs the forecasting website SnowAlarm.com. “If it crosses a certain threshold, then they refer to that as a bomb, because it’s so rapidly developing.”

The system is paired with another weather pattern called an atmospheric river that is supplying a constant flow of moisture into the storm. The strength of these atmospheric rivers is classified on a scale of one to five. This one is a five and is causing major flooding in some areas along the West Coast.

“When you think of a river, it is this channel of moisture, of water, and that’s really what it is in the atmosphere,” said Erin Walter, a meteorologist with the National Weather Service in Grand Junction. “It’s a really concentrated plume of moisture that’s carried across the Pacific Ocean, and as it moves inland, it can create very heavy rainfall and snow totals.”

Northern California is taking the brunt of that moisture as of Monday morning, but throughout the day Monday, the storm will move inland across the Great Basin, starting to bring showers to the Yampa Valley by early Tuesday.

Temperatures are expected to be above average ahead of the storm Monday — the forecast high is 67 — that is part of a push of warmer air from the south that the storm will be competing with as it moves in.

Weissbluth said the storm will likely start out as rain Tuesday morning, especially at lower elevations. The coldest air in the storm arrives in the afternoon, which is when he anticipates it will turn to snow.

“I’d say 3 to 6 (inches) up top is a pretty solid guess,” Weissbluth said. “Down here, it might be kind of a cold rain to start out Tuesday morning and then switching over to snow in the afternoon. I’d say 1 to 4 inches later in the day and overnight.”

But Walter said she expects the snow to linger in the area, as well.

“Once the snow finally diminishes Wednesday evening, … we should see 4 to 6 inches right along Steamboat, and it really ramps up as you go up higher in terrain,” Walter said.

By Thursday, things are expected to clear up again, and temperatures will start to rise, reaching the mid-50s each day this weekend.

The National Oceanic and Atmospheric Administration released its official winter weather outlook Thursday, saying it will be a La Nina winter for the second year in a row.

What that means for the Yampa Valley isn’t entirely clear in the report, as it predicts equal chances that the area will have either less or more precipitation than normal.

“Often, Colorado falls in the equal chances (area). It’s just basically seen as not a strong signal either way,” Walter said. “In a typical La Nina, I would expect Steamboat to see more precipitation early on in the season, and then it tapers off after the New Year — but take that with a grain of salt.”

The NOAA update, which covers December to February, also shows most of Colorado is expected to have temperatures slightly above normal, and drought is expected to persist or get worse across much of the state.

“Looking at the pictures, I’d say this is rather unremarkable for our area,” Weissbluth said after looking at the long-range forecasts.