No Sign of Lowland Snow Next 10 Days

December 10, 2019

9:30pm Tuesday…

These first 10 days of December have been mild; quite a turnaround from that cold Thanksgiving week.

web_PDXTemp_13days

Of course we’ve been on the dry side since early October too.  Both Oregon/Washington saw a dry fall.  Take a look at the precipitation percent of normal for the past 60 days

anomimage

I do see three wet days ahead.  A Pacific system moves inland tomorrow afternoon followed by lots of post-frontal showers in the colder airmass Thursday and Friday.  There are hints we could see vigorous showers Thursday with maybe hail or thunder.  Then I see another somewhat “splitty” jet stream setup this weekend and part of next week.  That’s a return to weak systems.  You can see the upper-level system heading into California on Tuesday

gfs_tuesday

All models advertise strong southwesterly flow of some sort later NEXT week (about 10 days out).  The GFS 500 millibar heights and anomaly for Friday the 20th…

gfs_fri20th

What I don’t see, at least during the next 10 days, is any setup for lowland snow or a freeze.  I’m sure not going to bother putting on my snow tires for now.  Maybe next week.

Snow levels will vary between 2,000-6,000′ in the next 10 days.  Probably lowest this weekend.  Notice not a single one of 51 ECMWF ensemble members produces snow in Portland through Christmas Eve either!  Leading up to the Thanksgiving cold spell there were multiple ensemble members hinting that we might see some snow fun.  But you see nothing here.

ecmwf-ensemble-KPDX-indiv_snow_24-5979200

I’ve also been noticing the consistency in those ensembles for 850mb temps (temp in Celsius around 4,000′) through the next two weeks.  Not a single member down below -6; that’s when I start getting interested in lowland snow setups.

tseries_850t_000-360_Portland

The last time we saw snow in December was Christmas Eve 2017.  You may remember a couple hours of light snow, followed by a bunch of freezing rain.  It was a “Silver Christmas Morning” in 2017.

December Snow PDX 2017

To summarize

  1. There’s no sign of lowland snow or a hard freeze in the next 10 days, possibly longer
  2. That means we’ll make it at least 2/3rds of the way through December without snow
  3. We can’t see much beyond that point, although there are no hints of anything a little farther out.  It’s too early to know if we’ll be close to snow or ice for Christmas Week

Chief Meteorologist Mark Nelsen