Quick Tuesday Evening Update

February 4, 2014

Flurries ended soon after sunset and now cold and dry air is pouring into the area.

Models are  a mess this evening; thus we have a very challenging Thursday-Sunday forecast.  What seemed like a very clear “moisture returns and rides over the cold air Saturday” event is now something a bit different.  It appears the arctic boundary (dividing line between cold and dry air and milder air) will sit across central/southern Oregon the next few days.  Several surface lows and/or weak disturbances in the upper atmosphere will ride along that boundary Thursday and Friday.  Then the stronger warm front finally swings north (probably) on Saturday.  Depending on which model and which run you look at, each of those waves of moisture could bring snow to parts of the Willamette Valley.  As of now our RPM and GFS don’t really bring much of anything to the Portland area until late Friday night.  The new 00z ECMWF looks similar, so our forecast is staying that way.  Of course it’s only late Tuesday and I’m pretty sure with the boundary so close to us that things will change.

I am very confident that we’re not getting out of the cold air until at least Sunday.  The 00z GFS and 00z ECMWF don’t have any southerly wind in the metro area through Saturday.  Anyone that thinks they can predict snow totals for Saturday, on a Tuesday evening,  in a pattern like this, is nuts!



More tomorrow…enjoy the fresh Canadian air and wind tomorrow!

Chief Meteorologist Mark Nelsen

Snow Showers Today

February 4, 2014

Radar and observations (looking out the window) show snow showers have popped up the past few hours over the Willamette Valley.  As of 11:45am they seem to be increasing in intensity.  There is a weak surface area of low pressure of the coastline, and the arrival of colder air from the east overhead may be giving a little lift to the cloud cover.  That’s the cloud cover that I thought would be gone by this morning.  Here’s the view down in Salem, which seems to be getting some of the heavier showers:

Commercial and Kuebler_pid2446

Regardless, it’s a bit too warm during the daylight hours for snow to stick.  Road surface temps in the metro area are around 40 degrees or so, and air temps are into the mid 30s.  IF snow showers were to continue past sunset, then it’ll be plenty cold for snow to stick.  But they should dissipate during the afternoon.  We’ll see.

Two other things I notice this morning:  Models have overdone the cold air banked up against the east side of the Cascades.  The WRF-GFS showed 5,000′ temps around zero to +5 by this morning on the east side of the north Oregon Cascades.  Instead it’s 13 and 12 at Timberline and Meadows.  Oops…  The other is that models obviously have overdone the cold air at the surface in general.  Sure, it’s still a blast of arctic air the next few days, but high temps will probably end up in the lower 30s instead of 20s.

Chief Meteorologist Mark Nelsen