Since there is a good amount of instability in parts of the region, snowfall rates could be quite intense with locally up to 4 inches per hour possible this morning. This will make any travel in the region extremely dangerous.
Heavy rain is also starting to spread down the coast with localized flash flooding possible. Additionally, gusty winds over 40 mph will be possible in parts of central and southern California as the storm slides into the region.
The heaviest bands of rain will move southward towards Southern California Sunday night and into Monday, with locally 2 to 4 inches of rainfall possible. Heavy snow will continue for the Sierra through Monday as some snow also will develop in some of the southern California mountains.
The precipitation should decrease in coverage on Tuesday as the system moves deeper into the intermountain west. Locally, 4 to 6 feet of mountain snow will be possible in the northern and central California mountain range and 2 to 4 inches of rain will be possible in the California coast. Up to a foot of snow will be possible in the Southern California mountains.
As we head into the middle of the week, this storm will begin to interact with another storm that in the central U.S.
Late Tuesday and into Wednesday, there will be two distinct areas of unsettled weather. One being heavy rain and thunderstorms in the central U.S., especially the southern plains, as well as regions of rain and mountain snow in the intermountain west.
Then on Thursday, a more prevalent storm system will take shape with widespread mountain snow from Montana to New Mexico and heavy rain and strong storms for the plains and Midwest.
Late Thursday and Friday, the storm will then race off to the north and east and likely bring a round of snow to parts of the upper Midwest.
Additionally, a line of strong storms will form along the cold front that will move into the Ohio and Tennessee Valleys, eventually reaching the east coast by the end of the week.
The main threat that could result from this storm system is several rounds of heavy rain in the southern plains and parts of the Midwest. This could lead to increase flooding potential as get towards the end of the week.