Snow/Ice Possible Later This Week

January 30, 2017

4pm Monday…

Late Evening Edit:  A few new thoughts at 10pm with all evening models in nowupdates in red

It’s been a very gloomy day out there with low clouds hanging over most of the metro area.  The good news is Tuesday will be a much brighter day; I expect clouds to break up to partly to mostly sunny skies in the wake of a cold front passing through the region.  The air coming in tomorrow is cooler and drier, thus the increasing sunshine.

Of course what we all care about is that Wednesday-Friday time period I mentioned in the posting Sunday night:

THE BIG PICTURE

The 2nd half of this week we’ll be in a “conflict zone” in the Pacific Northwest where the colder air from the north moves down under milder/moist air above.  That “zone” seems to want to hang out somewhere near the Oregon/Washington border Wednesday through Friday according to most models.  But details are very uncertain through that whole 3 day period and I don’t have a lot more info to give you this afternoon…we’re just going to have to wait until we get closer (Tuesday) to see if we can get some better forecast agreement among the models.  But I can give you a few more tidbits this afternoon that might help with you late week decision-making…

HIGH CONFIDENCE ON THESE DETAILS:

  1. A cold east wind arrives in the Gorge tomorrow and tomorrow night.  It’ll blow quite hard Wednesday-Friday in the Gorge and east metro
  2. Expect high temperatures mainly 32-38 in the metro area Wednesday-Friday
  3. Temperatures remain at/below freezing Wednesday-Friday in the Gorge.
  4. At some point we’re going to see sticking snow and/or freezing rain in at least portions of the metro area during this period.
  5. The Gorge turns snowy/icy again with a little snow late tonight/Tuesday AM, then quite a bit likely Thursday/Friday.

LOW CONFIDENCE:

  1. Will we actually see snow sticking in the metro area Wednesday?  Possibly, but as of now most models are mainly dry for that day.  This could change. (10pm update)  All models except our RPM are pretty much dry Wednesday.  I’ve taken the chance of anything other than flurries out of the Wednesday/Wednesday night forecast.
  2. How much moisture Thursday/Friday?  Some models are mainly dry through at least midday Thursday and then light freezing rain Thursday night/Friday AM.  Others have more widespread snow Thursday before a changeover.  I’m sticking with a later arrival (sometime Thursday) for now. (10pm update)  Definitely a later Thursday & Friday event showing up now.  Thursday might even be dry to start.
  3. The cold air mass over us Wednesday-Friday isn’t nearly as cold as what we saw in the first half of January.  That means it’s possible even IF we get a bunch of precipitation Thursday/Friday, some areas could be above freezing west of the Cascades = less frozen precip.  Another reason the forecast is very tricky.

Will there be school closures?  Not through Wednesday, but we’ll see about Thursday & Friday.  (10pm update)  It’s possible no road issues until later Thursday

Note the preferred ECMWF model is quite dry and/or not quite cold enough all the way through Friday for most areas west of the Cascades:

ecmwf_snow_fridaymidday

While the 18z GFS has a dusting to an inch or so.  gfs_18zsnow

The 12z WRF-GFS is slightly snowier.

wrf_snow_12z

Our RPM is similar with very light snow totals.  But it also thinks it’s above freezing even in the metro area all the way through Thursday midday.  That’s unlikely:

rpm_snowaccum

The big message here is that as of this moment no models are showing a huge snowstorm or major ice storm in the western valleys.  But we all remember the January 10th snowstorm though when all that moisture appeared out of nowhere!  A good reason to keep an eye on trends in modeling and satellite imagery of course.

Stay Tuned!

Chief Meteorologist Mark Nelsen