Is Winter Over? Probably Not, But Could Be

February 7, 2013

MarkWinter_OverFork

The past 6-7 weeks have seen incredibly boring winter weather with just occasional weak weather systems moving through the Pacific Northwest.  The Christmas Day snowstorm across much of the region was the last time we had some real excitement.  Of course below 1,000′ west of the Cascades it just rained at that point.  We have consistently seen either split-flow, ridging over us, or ridging nearby keeping us drier than average.  I don’t think there has been a single high wind warning along the Coast since before Christmas either.

Which begs the question…Is it time to stick a fork in this winter and call it done?  No, not yet.  It’s a bit too early.  Lets recap our 4 main types of “winter weather” we’ve seen we see here in the lowlands:

LOWLAND SNOW:

MarkWinter_Over4

Sorry kids, but for the 2nd consecutive winter we haven’t seen good snow that is “sleddable”, at least during the daytime.  We haven’t seen anything other than brief, marginal, wet snowfalls since late December 2009 (the surprise snow event).  The last time we got 2″ or more snowfall that stuck around all day long was about 4 years ago, December 2008.

ARCTIC AIR:

MarkWinter_Over1

This is the 2nd consecutive winter without an arctic freeze.  Portland has only been down to 23, similar to last year.  Salem dropped to 20.  Of course we had quite a run of very cold high temps at the same time under the inversion in January.  But no extreme cold.  Close, but not quite the real thing.  And above 1,500′ it hasn’t been unusually cold at all.

FREEZING RAIN:

MarkWinter_Over3

A close call in mid-January but that didn’t pan out, so still no freezing rain in the city.  Eastern suburbs saw some in early January, but otherwise none.

FLOODING:

MarkWinter_Over2

We’ve only seen minor flooding on mainly coastal rivers so far, definitely not a significant flood winter.

That’s what we’ve seen so far.  Let’s put together the current outlook, which shows no decent chance for any of these 4 types of winter weather in the next 7-10 days.  That will take us to mid-month (15th-18th). 

What could happen after mid February?  MarkWinter_Over5

It’s probably better to state what is unlikely to occur, as you see in the graphic above. 

We’re probably done with these events:

  1. A Big Arctic Blast:  We could still get a relatively mild arctic blast in the 2nd half of February (2011!).  But even that extreme would only put us right around the lowest temps we’ve seen this winter.  So it’s very unlikely we’ll see a major arctic blast.  We’re out of time.
  2. Major snow/ice event that goes on for several days (like Jan 2004 & Dec 2008).  We just haven’t seen prolonged events where the high temps stay below freezing for more than a day or two this late in the season.
  3. A Significant Flood.  I can’t remember hearing or reading of any big flood after early February.  We just don’t get incredibly wet systems this late in the season.  Sure, a river or two could see flooding, but that’s it.

What could we still see?

  1. Snow.  We could still easily get a one day snowstorm of 3-10″.  I just made up the 10″, but you get the idea.  Several times in the past we have seen several inches of snow past mid-February.  In early March 1960 there was even an east wind type snowstorm with drifting snow out in the east metro.  Extremely rare, but it can happen.  And we all know a wet snowfall can occur (rarely) into mid March.  There is even the freak occurrence of wet morning snow in early April in the 1930s.
  2. Windstorm.  Not as frequent as the first half of winter, but I remember at least two in the month of March.
  3. Minor Freeze.  All it would take is cold Canadian air surging south to give us a mild arctic blast like we saw in 2011.  I mean “mild” when measured against all other winter arctic air intrusions.  Obviously the 2011 event was spectacular for so late in the season.

So is Winter 2012-2013 over?  It MAY be, but we won’t know for a few more weeks.

Chief Meteorologist Mark Nelsen


A Whole Bunch of Extended Range Maps

February 7, 2013

Very busy this week since Stephanie K. has been sick and I’ve got all 5 evening shows.  Luckily the weather is DEAD, DEAD, DEAD.

But I have some long range eye candy for you.

First, the 12z GFS and 12z ECMWF ensemble charts.  GFS is hanging onto some members showing colder air from the north with some chilly troughs after about Day 10.  The ECMWF is not.

tseries_850t_000-384_Portland

tseries_850t_000-360_Portland

Second, the twice-weekly monthly run of the ECMWF (last night’s 00z).  Ridge starts to retrogress, then everything appears to flatten out near the end of the month, eventually replaced by a seasonal looking wet pattern into early March:

500za_week1_bg_NA

500za_week2_bg_NA

500za_week3_bg_NA

500za_week4_bg_NA


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