Here’s the latest:
1. No freezing/snow issues in the lowlands from Portland south through at least 6pm. After that time things could change quickly, but more likely 8-10pm.
2. Will it snow in the lowest elevations around the Metro Area? Still a definite possiblity. I would be VERY surprised if there is not at least a dusting most areas by 10pm. I would also be surprised to see more than one inch.
Quite a bit more precipitation than expected today, that’s due to a stronger-than-expected area of low pressure developing right around Forks, WA this afternoon. Pressures down around 1000 millibars instead of the 1005 models were showing. Check out Tatoosh Island…northeast wind gust to 45 mph, while just 30 miles south a buoy is gusting from the west over 40 mph! That’s some great meteorological stuff.
That low should race SE and be near Pendleton by late this evening…opening the door for something very unusual here: a big surge of arctic air from the north/northwest WHILE a west wind is increasing through the Gorge. Almost every arrival of arctic air here in the Metro area is accompanied by that gusty east wind blowing out of the Gorge. That’s not happening this time around.
So the obvious question is…where is the cold air going to come from? Regardless of the depth and position of the low…ALL models show the big cold surge from the north this evening. Look at these numbers…2,000′ temp over PDX @ 4pm = 32 degrees (accounts for snow level a little over 1,000′ this afternoon). But by 10pm it’s down to 20 degrees @ the same elevation! So where is the cold air coming from again? Check out temps up around the Olympic Peninsula. The RAWS sites are that cold (or colder) at that elevation, they’ve been cooling all day. So once the low passes to the east, the cold air should whip around the back side of it. This is an incredibly cold airmass moving south in the upper-atmosphere, and a good chunk of that is moving in at the surface too. Should be fun to watch….let’s just hope there is still moisture around to generate SOME snow.
A side note: Don’t want to sound cranky, but I don’t have any tolerance for bad behavior here today. Especially with 50,000+ hits to this blog. I haven’t read comments yet, but I know some will get very upset and lash out when their big snowstorm doesn’t materialize, but you know what? That’s what forecasting weather is about. Sometimes it doesn’t turn out like you expect. Move on…
Chief Meteorologist Mark Nelsen