Monday, May 20, 2019

Should California Be Renamed the Evergreen State?

Times change and recent meteorological trends suggest that Washington State should pass on its title of the Evergreen State to the more deserving State of California.   Washington State could become the Golden State, which makes sense with the vast sagelands and wheat fields of eastern Washington and the dry conditions over western Washington.

OK, let's make the case for the switch!  Here is the percent of normal precipitation since January 1st over Washington State. Much of the Cascades, western Washington, and northeast Washington received only 50-70% of normal.  Ouch.

But California, the supposedly Golden State, has been uniformly wet, with large areas enjoying more than 200% of normal precipitation.

Who had more precipitation since January 1st, San Francisco or Seattle?    San Francisco, of course, with 18.31 inches compared to Seattle's lowly 13.71 inches.

Snow in the mountains?  Skiing into the summer?   California peaks have been buried in the white stuff and CHAINS have been required over major mountain passes.  Some CA ski areas plan operations into July!

California's reservoirs are full of water.   Washington State reservoirs are ok, but well below capacity

This situation is not temporary--there is no end in sight.   The latest forecast from the European Center for accumulated precipitation over the next week (below) shows plenty of wet stuff over the Sierra Nevada and northern CA (1.5-4 inches), with some of that precipitation extended into normally arid eastern Oregon.

Washington State?  The arid leftovers, with most of the state getting a few tenths of an inch (with a bit more over the Cascades).

So what is going on here?  Why is Washington State and California exchanging places?  The key issue is the anomalous upper level flow pattern, with the jet stream heading into California, plus an usually persist trough of low pressure somewhere around CA.

A very revealing diagnostic was created by National Weather Service meteorologist Alex Tardy of the San Diego office.  It shows the difference from normal of the height of 500 hPa surface (thinking of it as the difference from normal of pressure at around 18,000 ft).  Unusual ridge of high pressure east of British Columbia, but a band of much lower than normal pressure heading into California.  Striking. 

This pattern pushes a strengthened jet stream southward into California.  And things are NOT going back to normal soon.  The upper level (500hPa) forecast map for 2 AM Tuesday shows the jet stream (where the lines are close together) heading into California, with a low pressure areas moving southward into northern CA to its north.

Fast forward to 8 AM on Sunday.   An area of low heights/pressure moving into California. Clouds and precipitation will extend over the southern part of the State.

The second half of May 2019 will be the wettest in CA history for many locations.

California is going to be green for a while.  And the fire season in California and Oregon is going to be seriously delayed.