The MJO has caused an extension of the East Asian jet stream this week which is helping to pump a ridge in the Eastern Pacific keeping us warm and dry. The PNA signal is headed into negative territory for the first time in a while and forecast to stay there through the rest of March. As the MJO progresses through the Pacific and/or weakens I would expect the -PNA pattern to take over. That pattern is a trough for the West Coast with colder weather and increased chances of storms. I have been saying for a while that once Spring hits it should warm in the East and Winter should settle over the West for a while into April, especially with all the cold water in the Eastern Pacific.
The ridge of high pressure in the Central Pacific will begin to move East this weekend. Instead of pushing the low pressure North of Hawaii East, it looks like it will build over the top and keep a storm system trying to drop down the West Coast to our North. We should still start to see some cooler and more breezy weather by Sunday. Highs on the mountain may drop into the 40's Sunday and Monday and down into the 40's at lake level as systems pass to our North.
Just about all of the forecast models are in agreement that the ridge of high pressure builds into the Gulf of Alaska and then retrogrades West out towards 170w in the Pacific next week. The low pressure North of Hawaii then begins to move East towards the West coast. Some of the forecast models combine that with cold low pressure moving down the West Coast to bring a decent storm Tuesday through Thursday next week.
If the -PNA pattern holds the ridge may be making its home in the Central Pacific the rest of the month which could allow some more storms into the West coast. It's hard to think about snow in the Spring weather, but I'm not quite ready to write off Winter yet. I think there could be a few more suprises the next 6 weeks. BA