Valentine’s Day has come and gone.  Here in the Pacific Northwest, this is the time that winter weather geeks begin to throw in the towel on any more interesting cold/snowy weather for the season.  There’s a strong historical precedent for this, at least in Portland:  our coldest quarter of the year, statistically speaking, runs from the 3rd week of November to the 3rd week of February.  Nearly all of our BIG snowstorms, arctic blasts and ice storms occur during this three-month period.  In particular, it’s very hard for Portland to stay below freezing (or even below 35 degrees) all day long, any time outside this quarter.

Our normal high temperature is now 52 degrees F in the Rose City; about the same as mid-November.  The sun angle is as strong as the 3rd week of October now.  Obviously, it’s POSSIBLE for cold weather to come after the 3rd week of February, like it did last year.  In fact, record cold temps were shattered for early March, getting as cold as 6F in The Dalles!  But last year was an exceptional fluke, brought on by a “perfect” combo of late-season snowstorms, plus an arctic airmass that slid down over the snow-covered Columbia Basin in the first few days of March.

This winter has been much different than last.  Apart from some record flooding in NE Oregon, there has been very little to talk about ever since late November.  In fact, the first 15 days of February have actually been cooler than the entire month of January was!  That exceptionally mild January is probably why we have flowers starting to bloom now, as evidenced by Thursday’s trip to the Mississippi neighborhood in North Portland:

The rain and the flooding are going to take a break for a little while.  We’re entering a drier and somewhat warmer pattern for this work week.  Skies clear out tomorrow, and by Wednesday morning we have a weak upper-level ridge centered just to our north:

This is not a setup for an intense late February “warm spell”.  We’d need 850mb temps over Portland in the +8 to +12 range if we want 63-65 degrees temps at the surface.  Instead the airmass will be around +4 on Wednesday.  That should be good for mostly sunny skies and highs up in the mid-50s for a couple days.  Nothing really exciting, but enough to remind us that spring is just around the corner.

We have a chilly trough that will dig along the West Coast this weekend, bringing moderate valley rain & mountain snow with fairly low snow levels Saturday night & Sunday.  But then it dries out again next week, possibly leading us into a period that is seasonably cool, but unseasonably dry:

The GFS ensembles are not showing any sign of chilly air after next weekend’s trough.  It COULD come close to seeing snowflakes on the valley floor, if there is precip available to work with next Sunday night.  As of right now though, I’m not counting on it.

Based on the long-range outlook, I’m going to make a bold prediction:  Unless we see a quick dusting of wet snow next weekend, the 2019-2020 winter season is probably over for Western Oregon & SW Washington.  Yes, we can still get wet snow and cold troughs over our region well into March some years.  But there is no clear sign of that on the long-range models.  Even next weekend’s -7 airmass temps are pretty marginal for snow, especially during the daytime.

One thing we might see next week, after the trough passes, is some cool northeasterly flow with freezing temperatures at night.  That can definitely still happen in late February and early March, if skies are clear, dewpoints low, and the airmass not too warm.

I’m not going to pull out any forks as of today, but be prepared for the fact that we’re likely turning the corner into early spring.  This week’s mild sunshine will be our first preview of what is hopefully plenty of nice outdoor weather, this March through May.  I’m off work Tuesday and am going to take full advantage of the sunshine.  Enjoy!  -Karl