First Major West Coast Atmosphere River Getting Their Wet Season Off To A Doozy Of A Start

We've entered the season in which pretty big storms come off the Pacific Ocean and hit various parts of the West Coast, sometimes intensely, sometimes not.  

Satellite view shows the strong "bomb" cyclone centered off
the Washington and British Columbia coast this afternoon.
It's the comma shaped thing on the right hand side of the 
image. Part of the atmospheric river is visible as that
long white streak heading west from the storm

The first major storm of the season looks like quite a doozy. What is known as a bomb cyclone will team up with an atmospheric river .

A bomb cyclone is a storm that's intensifying super fast. A storm is a center of lower air pressure. In general, the lower the air pressure in a storm, the stronger it is.

 Technically, if the air pressure in a storm drops by 24 millibars within 24 hours, the storm is a bomb. 

Bomb storms are often dangerous they are simply strong and getting stronger. You can plan on a lot of wind and precipitation if you're hit with a bomb cyclone, and that will be the case with this "bomb"

This storm could be the most intense in the region since at least the 1940s. 

 An atmospheric river is a long narrow corridor of deep moisture.  When one of these comes a shore, a 200 to 400 mile wide band,

So we have a strong storm and a stronger than usual atmospheric river. The result is a West Coast mess that started today. 

THE RESULT

Between this afternoon and Sunday evening, ten to as much as 15 inches of rain to northwestern California and southwestern Oregon. 

NOAA's Weather Prediction Center says that by Thursday, there's a high risk of dangerous flooding in parts of northwestern California. High risk flood alerts from NOAA happen only about four times a year and it's exceedingly rare for them to be issued three days before the event, as this one was.

High risk days account for two-fifths of all U.S flood deaths and at least 80 percent of all flood damage. So this is serious. 

Emergency managers are especially worried about mudslides and debris flows, especially on slopes that suffered wildfires in recent years.

The storm is accompanied by those high winds. Many neighborhoods are pretty heavily forested, which means trees could fall on houses. People are being warned to stay in interior rooms on the lowest floors of their homes because of this risk, 

Those winds tonight could gust to 70 mph, with possible 85 mph gusts near the beaches. 

Ten to as much as 20 inches of rain could
fall in the yellow shaded area of 
northwest California and southwest
Oregon over the next several days. 

The rough weather extends all the way to Washington and British Columbia. High winds are expected even in the big cities of Seattle, Tacoma and Vancouver, Canada. 

Blizzard warnings are up for Washington's Cascade mountains, 

Previous to this storm, some strong systems have hit British Columbia, and sideswiped Washington State with some decent rains. But points further south have had just small introductory systems to introduce the rainy season.  

This will be a real slap of reality and could be the start of a rough winter on the West Coast, especially roughly from San Francisco north.  There's a La Nina weather pattern, albeit a weak one, and that often cause extra storminess in the Pacific Northwest

WEST COAST STORM AND VERMONT

The West Coast storminess is unrelated to the super welcome precipitation that we're expecting starting Thursday. That one got energy from a previous storm that came ashore from the Pacific a few days ago. 

Despite the power of what's hitting the West this week, I so far see few signs of that storm spawning anything extreme in our neck of the woods.   

One piece of that atmosphere river should come through New England in about a week as a modest system with light precipitation. After that, the weather pattern seems like it could be active for us, but that's uncertain.