Quiet For Now, But Stormy Ahead!

January 6, 2011

Next week may be the “big week” of this winter.  Why?  because it appears (as I posted previously) that there is probably going to be a spectacular meeting of Pacific moisture and cold Canadian air over the Pacific Northwest.

I’ve looked at the last 24 hours worth of models, including the brand new 00z GFS and 00z ECMWF.  We also have access to the precipitation on the ECMWF here at KPTV, which is nice.  What do I see?

Cold and dry air pours into the Pacific Northwest over the weekend, moisture appears limited, but we could get a dusting of snow just about anywhere Sunday morning.  Then the cold and dry wind starts pouring in from the east (Gorge wind) later Sunday.  That lasts through at least Wednesday.

Models are in very good agreement now, showing precipitation pushing into our region by late Tuesday night.  Actually the 00z GFS and ECMWF are in very good agreement all the way through Wednesday (that’s 6 days out…very good).  Surface low pressure moves right across northern Oregon from west to east.  This is not a pattern that scours cold air out of the Gorge and generally not out of the Metro Area either; note how tough it was to do that a few days ago with weak low pressure to the north.  That alone argues for a snow and/or ice storm Wednesday here in the Metro area and north plus a big snowstorm in the Gorge.

The ECMWF and GFS diverge slightly after Wednesday.  The GFS is slightly farther north with the stronger wave on Thursday, while the new ECMWF brings that one right across northern Oregon too…GFS would change us to freezing rain or maybe just rain, but a second tremendous wave of snow/ice in the Gorge and SW Washington.  The ECMWF would give us a massive ice storm and and 2nd wave of snow or ice in the Gorge.   What happens beyond Thursday I don’t care about as much since it’s beyond the 7 Day forecast. 

To sum up:

1. The Columbia River Gorge is likely to see a major snow/ice storm Wednesday/Thursday next week if models remain similar to what they are showing now.  By major, I mean damaging ice amounts or 20″+ snowfall.

2.  The Oregon Cascades will have their heaviest snowfall of the season…many feet of snow.  Mt. Hood could see 5 feet or more Wednesday-Saturday of next week.

3. SOMEONE west of the Cascades between Seattle and Eugene will probably get a significant ice/snow storm Wednesday and/or Thursday.  Having the cold air in place with the Gorge transporting dry/cold air into the Metro area helps us out here in Portland.

4.  If future model runs push everything north, then we could see just rain and Seattle-Vancouver BC gets a big snow/ice storm.

Lots of fun ahead!

Chief Meteorologist Mark Nelsen

Impending “Snow/Ice Catastrophe” Sand Box

January 6, 2011

This post is for hard-core weather discussion, rants, or arguing about models.

Bypass this post if you are a casual visitor, want to know what it’ll do in your neighborhood or have any other questions.  Keep all other discussion in the posts below or I may delete your comment.

Only a few minor rules:

1. No swearing or foul language.

2. No personal attacks.  By that I mean comments about personal life etc… If you think someone’s forecast is horrible, go ahead and point that out.   I also don’t care if you rip apart my forecast…I’m a big boy.

3. No complaining about someone picking on you in here, if you don’t like it don’t come in.

This didn’t work out too well last time…all of a sudden everyone was playing nice, which WASN’T the point.  Plus a bit confusing.  We’ll try again.