This is a posting of a blog entry from Facebook that never made it onto this site.  My apologies…because it’s a good tale of what is still theoretically possible in our climate in March.

=======================

Yup, it’s time for one of those dramatic forecast titles.  For the past two or three days, model runs have been digging a cold and wet upper-level trough directly over us, beginning tomorrow Saturday and continuing through Tuesday morning.  This time it happens to be a “maritime subarctic” airmass that originates as arctic air over southern Alaska, but gets pulled southward across the water instead of the land.  This pattern is very common in late winter and early spring in La Niña seasons.  It usually doesn’t produce a LOT of sticking snow at the lowest elevations, but occasionally a 1-2″ accumulation can show up.

The Coast Range, Cascade Mountains, and much of Eastern Oregon are all elevated enough to avoid the “surface layer” of the maritime airmass.  They will get pummeled with a major late-season snowstorm.  The lowlands are always tough to call in March.  Unless you have either a really cold airmass (-8 or -9 at 850mb) or a steady, heavy precip – you are unlikely to get any stickage in the lowlands during the midday and afternoon.  The powerful sun angle just heats the bottom 1,000 to 1,500 feet of the airmass, a little too much – and temps climb into the low/mid 40s by day.

This is one of those patterns that has snow in the hills by day, and lowlands by night.  We could easily see a quick inch or two just about anywhere that a solid band of showers passes over during night or early morning.  I see that Wunderground has the snow icon out for Saturday morning as well – I’ll assume it means the higher hills and ignore it.  But I think each of the next three nights WILL be cold enough for snow showers in the lowlands, if and where precip is available.

I’m not going to show the snow maps, but they all show anywhere from 1″ (low end) to 4-6″ (high end) below 500′ spots.

But for fun, here is the 12z GFS, valid for 10pm a week from tomorrow evening:

There’s an 850mb temp of -9 over Portland and The Dalles that night, which is about as close to an arctic blast as you can get in the 2nd week of March.  Basically it appears we are going to have TWO cold waves in March:  the first this weekend and the 2nd, beginning the weekend after.  That means lots of low snow levels and high temps only in the 40s at the lowest elevations; a solid 10-12 degrees cooler than seasonal norms. Whew….I guess winter isn’t over yet after all!

================

Sadly, the whole mid-March cold snap had completely busted, just three days later.  We ended up having a snow tease for the first weekend of March, however – including a rare snowfall on the extreme southern Oregon coast (Port Orford, Gold Beach, Brookings). 

At their wildest (the 12z and 18z on March 5), the GFS maps went as far as to show an arctic airmass in northern and eastern Washington (-12C over both Seattle and the Tri-Cities, and about -15C over Wenatchee and Spokane!) for the second weekend of March, and a Columbia Gorge snow/ice storm with east wind on Tuesday the 14th.  I consider myself a “journeyman” weather geek with a solid 6-7 year experience of reading long-range maps.  And let me tell you…I have NEVER seen an actual arctic blast try to show up, that late in the season before.  Not even in the La Niña Marches of 2011 and 2012. 

The above scenario, of course, did NOT come to pass.  But for a while it had very strong upper-level ensemble support.  If our La Niña hadn’t died out several weeks before, I believe we would have stayed much colder this March in the PNW. 

To sum it up, this season was not only a historically cold and snowy winter for the Columbia River Gorge and Portland metro area.  It also was a reminder that, yes, the Wishcasting Express does sometimes sell tickets for its ‘March Madness Encore Tour.’ 

MORAL OF THE STORY:  Think twice before pulling out the fork, especially in years like this!