California Does A Flip Flop In New Stormy Pattern

Forecast amounts of 
rain and melted snow 
in California over the 
next 7 days could 
exceed a foot in some spots

That new, stormy pattern in the United States (except for here in Vermont!) is about to give some serious weather whiplash to California. 

The drought out there is severe - a symptom of it has been the weird January brush fires out there - but they're starting to get relief. 

Rain has been already starting to fall out there the past couple of days, and it looks like it will continue to do so off and on for the next couple of days. With snow in the mountains of course. 

Great! They can start chipping away at the drought and build up some winter snow pack for water usage in the summer. 

But then the fire hose starts.  Strong storms and an "atmospheric river" will dump enormous amounts of rain in parts of the state and even more enormous amounts of snow later this week. 

Although the following is probably an overestimate, one computer model dumps up to 30 FEET of snow -the equivalent of 23 inches of rain on the Sierra Nevada mountains in less than two weeks time. 

Lowland areas could get half a foot of rain just in the next seven days. 

In the grand scheme of things, this is mostly great. The past six months have been the driest, or nearly the driest on record in much of California. 

The problem is, some of this will be too much too fast, especially in areas that had those big wildfires. Torrential rains in these areas will create some dangerous debris and mud flows.

Remember, the fires eliminated brush and trees, whose roots normally hold soil and rocks in place.  Now, everything is loose, and can come crashing down on neighborhoods at the bottom of the hills. 

People could find their houses narrowly escaped last year's wildfires only to have them wrecked by mud and debris flows. 

While I'm reluctant to pin one weather event on climate change, this abrupt jump to drought to flooding is consistent with climate change on the West Coast.

Atmospheric rivers in the winter - those channels of super wet air that hit different parts of the West Coast during the winter - usually have more good consequences than bad.  They provide much of cold season rain and snow that sustains California during their bone dry summers. 

They can get out of hand, though. One such event in 1862 flooded most of California's Central Valley, including almost all of Sacramento.  

Climate scientists are saying that while intense droughts are becoming more frequent in California, the risk from atmospheric rivers is paradoxically rising 

A warmer world means the air can hold more moisture, so atmospheric rivers can become more intense, causing higher risks of flooding. 

Some studies suggest there could be a three fold increase in the type of 1862 mega-atmospheric rivers by the end of the century in California.

Now that California is our most populous state, an 1862 type flood would be catastrophic for the state, and the nation as as whole.  

Nobody is suggesting the deluge later this week will turn into anything like 1862.  For one thing, it won't last weeks, like 1862, so there won't be time for flood waters to accumulate. It'll taper off within a few days.

And as noted, there's a drought in California right now. There's plenty of room for excess water to drain, aside from the those debris flow-prone areas and urban areas, where street flooding is likely. 

I'm sure skiers will also rejoice in the incredible snows in the Sierra Nevada - once they manage to re-open the roads out there after the anticipated snowy deluge.