California Enjoys the Northwest's Water

 Two years ago, media outlets were headlining strident messages that California had moved into a "megadrought" and that there was little hope for relief.

Story after story claimed that global warming had permanently changed the situation and that California's reservoirs would remain unfilled.

Fast forward two years and these apocalyptic warnings appear more like a rendition of chicken-little than reliable climate science.

Massive rainfall has hit the Golden State, while we in the Northwest are enjoying a warmer-than-normal winter with less snowpack than normal.

Below is the percent of average precipitation for the last month over the western U.S.  Some parts of California have received over 400% of normal!

To illustrate the soggy California situation, below is the accumulated precipitation at Los Angeles since October 1 (the current water year). Brown indicates normal values.   LA is now running about 40% above normal

Compare this to Seattle (below).  We are slightly above normal.   Precipitation-wise we running nearly exactly on climatology.   That may surprise some.

As I have described in several previous blogs, we are now experiencing El Nino conditions, which tend to make California very wet, while our area generally experiences near-normal precipitation.   

The latest forecast of accumulated precipitation through Tuesday shows a continuation of the pattern with heavy precipitation expected in California.  And yes....only modest precipitation over Washington.  Oregon enjoys a piece of this wet bounty.

The origin of this wet situation is a strong El Nino low center off of Califonia, illustrated by the upper level (500-hPa pressure, about 18,000 ft) at 10 PM on Monday.  The purple shading indicates an unusually strong low.  I am getting tired of this pattern.

The current extended prediction of accumulated precipitation through April 1 by the European Center model suggests this pattern is not going away, with very wet conditions over California, but drier than normal in the Washington Cascades (see below).

But what about the Northwest snowpack during the next few months?    I will leave that to an upcoming blog.

Some Lowland Snow is Coming Western Washington Late Wednesday and Thursday

Historically,  the window for lowland snow over western Washington closes the last week of February.

It appears that we are going to get some flakes before it is too late..... but not that many.

Let me start by showing you the latest forecast by the UW WRF prediction system.    Below is the forecast sea level pressure and low-level temperature map for 10 PM tomorrow (Wednesday) night.  

Cold air (blue color) is found in British Columbia, Alberta, and Montana.  Some pushes into eastern Washington.

A low-pressure center moves on to the northern Oregon coast, drawing cool air into western Washington.  The trouble for western Washington snow is that the low is a bit too far south and temperatures are marginal.  This pattern would push cool northeasterly flow through the Fraser River Valley into Whatcom County and the San Juans.

The latest UW high-resolution forecast for snow accumulation through 1 PM Thursday,  shows some lowland snow from roughly Olympia to Chehalis, and plenty over the south Cascades.  The southeast side of the Olympics gets a few flakes as well.

The Columbia Basin gets some light snow.

Nothing exciting perhaps, but snowflakes are always of interest.   There is, of course, some uncertainty in the forecast, and the way to get at that is to examine an ensemble of many forecasts.

The City of Seattle SNOWWATCH website shows the ensemble forecasts for Seattle (see below).  The gray lines are individual forecasts, and the ensemble average is in black.  Many forecasts are going zero, but the average is about .5 inches and snow depth would be much less than that.  Perhaps a dusting.  Quite possibly nothing.

In short, I would not be getting the sled out, but you might spot a few flakes.