California and Oregon Have Been Getting More Precipitation Than Washington: Should We Care?

When it comes to precipitation along the West Coast, there are always winners and losers.   

Sometimes the jet stream, the conduit of storm systems, heads north into Washington and BC, and we are wet, while California is dry.

At other times, the jet stream heads southward to California, and they get the precipitation, and we are dry.

On relatively rare occasions, a huge ridge of high pressure covers the entire West Coast, so everyone is dry.

Over the past 60 days, we have generally had a pattern of dry north and wet south (see below).

This pattern has been particularly apparent over the past week, with central California getting hit particularly hard.

 

Thus, California has enjoyed the precipitation it needs to sustain agriculture and its large population... a very good thing. For example, all of California's reservoirs are all running above normal (see below), and the state's overall snowpack has increased substantially during the past month.

Why this recent precipitation distribution with wet California and a dry Northwest?  

Mainly, because we have recently seen a repeated pattern of a deep upper-level trough extending southward down the Coast, as shown by the upper-level flow pattern below (for Tuesday morning).

I should note that there is no reason to suggest that such patterns have anything to do with global warming.  The research is clear on this.    It is natural variability.

It is also clear that we expect the jet stream to move northward during late winter, and the atmospheric "fire hose" will return to our area.

What about the next few weeks?

The forecast precipitation total through next Wednesday, which I have some confidence in, shows moderately wet conditions from central CA to British Columbia, with the heaviest precipitation over southern Oregon.

Ensemble (many forecasts) from the US systems suggests around 30 inches of snowfall at Stampede Pass in the WA Cascades over the next week:

Beyond that period, forecast skill declines, but the major forecasting systems bring heavy precipitation into our region, so that the totals through early March get impressive over WA and BC (see below).

That also means a lot of snow in our mountains.

In short, I would not pay much attention to the gloom and doomers on social media and the climate change claims of some advocacy groups regarding our precipitation this year.  Reservoirs are in very good shape, and substantial precipitation can be expected during the next few weeks and months.