The season of solar spring began in the Northern Hemisphere at 7:27am PST, today Friday, February 3, 2017.  What is solar spring?  It is the quarter of the year, orbitally speaking, when the amount of incoming solar energy in a given hemisphere is increasing at the fastest rate.  Whew…was that a mouthful?

We weather nerds like to think of Northern Hemisphere Winter as running from December 1 through February 28/29.  Traditional calendars, on the other hand, define winter as beginning on the December 21/22 solstice (when days are shortest and the sun is weakest) and ending on the March 19-21 equinox (when we’re exactly halfway from weakest sun to strongest sun).  Both these calendars assume differing degrees of “seasonal lag,” the difference in timing between daylight cycles and seasonal temperature cycles.  And normally (though oddly enough, not the past few decades along the West Coast), the coldest temps of the winter tend to come some time after the winter solstice.

But traditional Celtic and Chinese calendar systems used a regime that assumes ZERO seasonal lag.  In this system Spring begins around February 3-4, Summer around May 5-6, Fall on August 7-8 and Winter on November 6-7.  Light and dark, not hot and cold, are the sole determinants of the season.  I would argue that this calendar system is a “purer” way of “telling” seasonal time – precisely because the cycles of light and dark are what ultimately drive the temperature cycle, NOT vice versa!

These four dates, called “cross-quarters” by the Celts, lie exactly halfway between the solstices and equinoxes.  (By “halfway” I am referring to orbital longitude.  If the quarter days are the 90-degree points in the orbit, then the cross-quarter days are the 45-degree points.)The early February cross-quarter was known as Imbolc to the Celts, Li-Chun to the Chinese and Setsubun to the Japanese.  There are even hints that the indigenous Anasazi in southern Utah, may have observed this festival in their own way!

The Celtic pagan festival of Imbolc eventually became co-opted by early Christians as Candlemas, celebrating the Virgin Mary after she fully recovered from her birth.  And this is the origin of the Groundhog Day legend:

“If Candlemas Day be fair and bright
Winter will have another fight.
If Candlemas Day brings cloud and rain,
Winter will not come again.”

Basically if early February is cold and gloomy, then winter is supposedly “getting itself over with” then and there, and Spring will start shortly thereafter.  But if it’s mild and pleasant and sunny?  Then Old Man Winter must be saving a few more punches for later on.

Yesterday I didn’t see any shadows outside:

So I guess we’re in for a fairly early start to spring?  Somehow my sense of La Niña seems to doubt it.  It started snowing again last night and has continued lightly for much of the day today.  That should transition over to ice pellets overnight, and then eventually rain.

A couple days ago it looked as though the late Thursday – early Saturday event we are currently going through, was going to be the last real tease of winter before milder February weather set in.  But now a surprise snow event seems to be cropping up in models for late Sunday into early Monday.  Not all models agree on the exact location of the snow front.  Basically what is going to happen is that we have very cold modified arctic air spilling out of British Columbia, over Vancouver Island and back toward the I-5 corridor from the northwest.

But it’s not actually the cold air that will cause the snow; it’s a stationary front between cold and warm air that will allow for heavy, steady precipitation that drags snow levels lower than they otherwise would get.  This is what happened in late March 2012 over the southern Willamette Valley, when 6-12″ of snow fell a couple days after the spring equinox.  

Here is the “Insanity Map” courtesy of the night’s NAM-WRF:

I don’t think I’ve ever seen anything like it over Western Oregon before!  12-18″ over the entire region?!?  How long would THAT take to melt out!

But here is the 00z ECMWF instead:

Somebody between Seattle and Salem is going to get a pretty significant snowstorm Sunday, IF the heavy/steady precip plan holds.  But location, location, location seems to be the key this time around.

That’s it for now.  Sigh…I really truly hope spring weather isn’t too far off now.