Expect Some Snow Tonight

11:30am Tuesday…

It appears that just about all of us in the metro area should wake up to a blanket of white Wednesday morning and snow should be falling too.

There are still some variations in all of our different weather models this morning, but they all show at least SOME snow and a few of the models are actually showing a real snowstorm by tomorrow morning/midday.  All of the models are in now until later this evening so this is a bit of a “final call” forecast-wise.

WHAT IS MOST LIKELY TO HAPPEN IN THE NEXT 24 HOURS IN METRO AREA

• Light rain showers the rest of the daylight hours
• East wind ramps up through the day and will be quite gusty east metro through the night, gusts 30-40 mph
• During the late evening (after 8pm), those light rain showers turn to light snow showers
• Temps drop to around freezing late this evening (well after 8pm), probably not a sudden freeze-up, but wet roads turn slushy/snowy. First in the hills where it’s colder, then lower elevations
• Clark county and east metro will only see very light snow showers, not a whole lot of accumulation
• Late tonight and the first half of Wednesday the snow showers turn to steady snow with temps at/below freezing
• By midday tomorrow when it’s mainly done, expect 1-4″ snow on the ground in the metro area, lightest eastside and north in Clark county.  Heaviest west metro
• Snow showers end tomorrow afternoon and then any wet roads will freeze Wednesday night with some clearing.

HOW THIS IS LIKELY TO AFFECT YOU

• This evening’s commute is totally clear, in fact most roads will be just fine all the way toward midnight
• Expect lots of school closures tomorrow in the areas where 1″ or more falls, maybe just some delays eastside and Clark county?  Depends on how much falls
• The AM commute could be quite snowy, especially if our “wetter” models are correct
• The PM commute Wednesday may not be too bad since we’ll probably go above freezing and many roads turn wet, especially arterials & freeways

WHAT COULD CHANGE?

1. Some of our models are wetter, which would be a real snowstorm late tonight and Wednesday AM.  2-5″ more widespread, I think that’s less likely
2. Temps only drop to 32-34 tonight, limiting snow accumulation on roads.  If that happens, roads would be in much better shape for Wednesday.
3. If the driest models are correct, and we wake up to only a dusting to 1″.  I think this is unlikely as well.

OTHER AREAS

Salem/Albany/Kelso/Longview:  Trace to 2″ snow late tonight.  There is an outside chance some freezing rain mixes in.  We’ll see

Oregon Coast:  Nothing to 1″ at best by sunrise Wednesday  Areas from Tillamook to Astoria MIGHT see snow in the morning, but that’s a real tough forecast.

Columbia River Gorge:  3-5″  not a big snowstorm, but it’ll add onto the big “base” you already have.  Until 8pm this evening there could be spots of freezing rain west end.  I’ve got maybe 1/10″ of glaze here at home from this morning’s rain showers (at 32 degrees)

 

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Is it possible to just make an easy snow forecast around here?  No, not most of the time.  And this time is especially tricky since some parts of the metro area may see very little snow and others get a real snowstorm by Wednesday AM.  It’s interesting that the NWS is going for very light accumulations all around with only a winter weather advisory, yet in previous storms they tended to go for the highest totals.  All part of the winter drama this year!  I feel better this morning that the general theme is the same across most of the modeling we use; the west side metro likely gets the most snow this time and least will be closer to the Cascades and north.

It’s also pretty clear that this is not like some of our previous snow events/storms in which a wall of snow starts falling and we quickly ice up.  In the case of this evening it’ll take awhile for cool air to work its way in from the east and precip intensity isn’t so great either through at least midnight.  Kind of a slow-starting snow “storm”.

One of my thoughts this morning has been “where is all the cold air going to come from to freeze us up tonight?”  Then I checked the WRF-GFS temp maps for 2,000′ and 3,000′ elevations.  The storm moving by to the south and low pressure to the southwest DO pull cold air right into the east end of the Gorge.  27 degrees at 3,000′ over Hood River/The Dalles right now drops to 12-14 degrees at that elevation by 4am!  Then that air is sucked through the Gorge, so I’m pretty confident the entire metro area will be 32 degrees or lower by sunrise Wednesday. But no, not a hard freeze tonight.

How about that morning ECMWF?  That’s my ‘ol trusty model and it’s forecasting a snowstorm for most of the metro.  It’s generating far more precip:

and that means more snow

The WRF-GFS is pathetic, but still gives a big 1″ or so west metro.  It would say you wake up to a dusting AT BEST for 2/3 of the metro area.

That model uses the GFS for its initialization…here’s the GFS:

Same idea with almost nothing central/east metro.

We’ll see how it all turns out, it almost never ends up exactly as any one model is showing…so in the end I decided to stick with the 1-4″ metro snow forecast, giving a little nod to the wetter ECMWF, but not ignoring the real dry models totally either.

Chief Meteorologist Mark Nelsen