After some very tranquil weather of late things are about to change. A trough in the Eastern Pacific is going to do the splits with the northern section headed across the Northwest while the southern section heads south-southeast and moves form north to south through California.
In the Northwest some rain spreads into western Washington and Oregon during Saturday with snow likely in the Cascades. Then a few showers linger on Sunday. East of the Cascades a few snow showers will survive. By normal standards this is a fairly hum drum storm for mid-winter.
Farther south rain and snow develop in northern California Saturday, spreading south through central California Saturday night and then into southern California late Saturday night or Sunday depending on how far south you area. Snow levels are going to be on the low side, 2,500 to 3,000 feet in the north to 4,000 to 4,500 feet in the south. This is not going to be a huge storm in precipitation amounts. Rainfall amounts generally ½ to 1 inch north to central and ¼ to ½ inch in the south. Snowfall of 6 to 12 inches in the Sierra and several inches in the mountains of southern California with all passes having snow and slippery travel.
There is a wild card in all of this. The European model is wetter and also slower in moving the storm out of California and into Arizona than the GFS. The models have been flip flopping on this all week and it is hard to pick a favorite. The gut feeling I have is that slower is better which means a few rain and snow showers could linger Sunday night in southern California and even part of Monday in the mountains and southeast California. This also has a bearing on Arizona as the GFS only brings a few snow showers to the mountains and its dry in the deserts. The European brings rain showers to portions of the deserts and a bit more snow in the mountains.
As for next week we also do not have a lot of agreement on the details of the pattern. But in general it looks like several storms originating from the eastern Gulf of Alaska push south in an increasingly strong northwest flow aloft along the Pacific Coast as the mean trough sets up in the Great Basin. This could bring several fast moving storms through that dig south into the Southwest.
Any shower and thunderstorm can contain heavy downpours, heavy enough to cause temporary, low-lying ponding.
According to all long-range models, the warmest area in North America compared to average will be over the Northwest.
No matter where you are, the sunshine gets more intense and causes quicker burning
A series of upper level lows moving off the Pacific brings, cool, cloudy, unsettled weather through Monday.
We (Accuweather.com) saw a way that this winter could end up being a bust not a boon even during a Super El Nino.
If you are in California, enjoy the warm sunshine now because next week will certainly bring a change.