California Storm Update: 6:15pm PST

6:15pm. All of the information below still looks valid, so I'm going to leave it up for the night. 

I have a busy morning tomorrow, but hope to have something up by late morning, California time. Please check back. 

Below are the forecast snow amounts in the Sierra from now until 4pm Sunday. 

As much as 40 inches are forecast to fall. Most of the storm will fall on Sunday and the heavy snow will continue Tuesday and, possibly, Wednesday. 

The flash flood threat will be high Sunday.

...and, Monday. 

Please scroll down to see preparation suggestions. 

[10:35am PST Update]

New data indicates thunderstorms are nearly certain with storm #2 over parts of Los Angeles, Ventura and Santa Barbara counties. The updated rainfall amount forecast is calling for more than ten inches in the higher elevations of Santa Barbara county and right at ten inches in Los Angeles county! 

I cannot overemphasize the importance of pre-planning.

• Create a "go kit" where you have essentials (a couple of changes of clothes, irreplaceable heirlooms, cash, ID's, some food like protein bars, bandaids and antibiotic cream, some bottles of water, et cetera). 
• Know where you are going to go if it looks threatening or an evacuation is ordered. Note: don't copy your neighbors. Do what authorities order. If it turns out to be a false alarm, count yourself fortunate.
• Keep your primary auto fueled.
• Get plenty of cash from the ATM.
• Power may be lost. Make sure you have flashlights and fresh batteries. 
• Know your escape route. Other factors equal, higher elevation is better.

[Posted at 8:25am]

I am adding a tweet from a California-based meteorologist:

[Original Post, 8:25am ]

Here is the latest update on the California storm situation. 

Storm Warnings and Watches

Color codes:

• Bright green: flood warning
• Dark green: flood watches
• Pink: winter storm warning
• Amber: high wind warning 
• Dark turquoise: winter storm watch 
• Purple: winter weather advisory, which is a lesser condition 
• Gray: dense fog advisory

While this will be a significant storm for the northern half of California, I expect the worst will be southern California. Before this is over, the storms may resemble the violent and destructive storms of 1982-83 El Nino. The Los Angeles Times has an article with victims of those storms. Over that winter, the storms produced highly damaging flash floods including of highways and rail lines, choking snow amounts, widespread power failures due to wind,  and LA's worst-ever tornado. 

The Los Angeles office of the National Weather Service has a helpful graphic pertaining to the timing an intensity of the first two of the storms expected over the next 11 days. 

Below is a graphic depicting precipitation amounts across the western half of the nation for the next seven days.

Note the high amounts of more than 7" of rain and melted down snow in the Sierra. Chain laws may be put into effect at times. Major transportation issues expect. 

The NWS is forecasting as much as 13 inches of precipitation for the mountains north of Ventura and Santa Barbara between now and Wednesday of next week. This will cause damaging flash floods, if the forecast is correct.  

There is already a flash flood warning (green polygon) for Long Beach, parts of far south LA and nearby areas until 11:15am. The radar is from 8:20am.

Here is the latest regional radar:

Of course, I will continue to provide periodic updates on this major storm situation.